Ford's answers to the NHTSA 6.7 Investigation

[ricatic]

There was a request for a link to Ford's answer's to the NHTSA investigation posted on a previous thread, since closed. Here is the link:

Ford's NHTSA Answers to the 6.7 investigation

This PDF is over 20 pages long. There are some interesting statements contained in the documents. My favorite is the one where Ford says they buy the pump from Bosch as a "black box" and do no testing of the component. It is closely followed by the tantamount admission that the pump will not provide a long service life when exposed to the poor lubricity fuel found in the US. You will have to do the math using the sales versus failure tables for the US and Canadian trucks. Eye opening difference to say the least...

Regards

[NewsW]

What about Delphi and DLC coatings:

http://delphi.com/manufacturers/dti/available-technologies/manufacturing-processes-and-logistics-for-license/batch-process-highly-adherent-diamond-like-carbon-coating/


Word on the street is Bosch is way ahead of them on using coatings.

[NewsW]

Let's take a look at Delphi's next generation solution (2,600 to 3,000 bar) and see what they had to do to make it work:

http://delphi.com/manufacturers/cv/powertrain/common-rail-systems/high-pressure-heavy-duty-diesel/


--------------------

Common Rail Systems

Delphi Ultra High Pressure Heavy Duty Diesel Common Rail System

The Delphi Ultra High Pressure Heavy Duty Diesel Common Rail System (UHPCRS) is designed for medium and heavy duty diesel engine programs with high pressure requirements. Delphi offers a complete common rail system including electronic injectors, common rail, sensors, pipes, ultra high pressure fuel pump, electronic controller and fuel filtration.

Delphi has earned a reputation for durable, high technology electronic unit injector and electronic unit pump systems. With the UHPCRS it has now developed a range of common rail systems with class-leading pressure capability and durability.

Benefits

Highly efficient, compact pump with integrated transfer pump
Engine oil-lubricated pump provides long term durability at high pressure operation
Fast response injector with small quantity injection control for precise combustion control
Fully flexible injection capability
Close coupled multiple injection capability
Bespoke injector body, including slim line valve stock for packaging flexibility
Wide range of nozzle options available
Ultra high pressure (up to 3,000 bar) capability provides the potential to minimize the need for aftertreatment
On board diagnostics and dynamic trimming capability
Target emissions:
Euro VI
Post-US 10
Post-Japan NLTR
Tier IV

Typical Applications

The Delphi Ultra High Pressure Heavy Duty Diesel Common Rail System is designed for four to 16 liter diesel engine programs. It is suitable for on- and off-highway applications.

Specifications
Peak pressure range 2,400 bar to 3,000 bar
Engine cylinder capacity 1.0 L to 2.6 L
Injector diameter 21 mm minimum
Pump Two or three plunger variants
Drive voltage 50 V

Performance Advantages

The Delphi Ultra High Pressure Heavy Duty Diesel Common Rail System is among the most advanced fuel systems in the world. It allows engine manufacturers to combine the benefits of ultra high pressure and fully flexible injection for optimized combustion across the engine speed range. This reduces the need for expensive aftertreatment systems and maximizes engine efficiency. With oil lubrication, Delphi has redefined common rail capability in terms of reliability and durability at high pressures.

[NewsW]

Here is the German Patent for Bosch that eliminates the need for a helper low pressure pump.

----------------------

Description: WO2009152659 (A1) ? 2009-12-23


HIGH PRESSURE PUMP ASSEMBLY FOR COMMON RAIL SYSTEM

Description of WO2009152659 (A1)



The EPO does not accept any responsibility for the accuracy of data and information originating from other authorities than the EPO; in particular, the EPO does not guarantee that they are complete, up-to-date or fit for specific purposes.

High Pressure Pump Assembly for Common Rail System

Technical Field
The present invention relates to a high pressure pump assembly for Common Rail system, in which a feed pump, a high pressure pumping unit and a fuel flow regulator are integrated together by a single casting.

Background Art

In fuel injection systems for diesel engines, Common Rail technology plays a major role in meeting the present and future exhaust emission standards, such as Euro 3 and beyond. Most European automakers now have Common Rail diesels in their model line-up, even for commercial vehicles. Some Asian manufacturers have also developed Common Rail diesel engines.
In a fuel injection system equipped with a Common Rail, a high pressure pump supplies fuel at high pressure into the rail, basically a tube which in turn branches off to computer-controlled injector valves, each of which contains a precision-machined nozzle and a plunger driven by a solenoid. The injector valves control the precise moment when the fuel injection into the cylinder occurs and also allow the pressure at which the fuel is injected into the cylinders to be increased. A flow regulator controls the amount of the high pressure fuel which the pump delivers to the rail.
For supplying high pressure fuel into a rail, a pre-delivery pump and a high pressure pump may be adopted. See, for example, EP patent publication No. 0,304,741, which discloses an inline pump for fuel injection systems.
In known fuel injection systems, the pre-delivery pump, the high pressure pump and the flow regulator are connected with each other and/or other components via pipe lines, resulting in a bulk and complex structure as well as a high cost. Summary of Invention
An object of the present invention is to provide an integrated high pressure pump assembly for Common Rail system with a cost-effective compact and simple structure.
For achieving this task, according to one aspect of the invention, a high pressure pump assembly for Common Rail system comprises a casting, a feed pump mounted to the casting for drawing fuel from a fuel reservoir and pre-pressurizing the fuel, a high pressure pumping unit mounted in the casting for receiving the pre -pressurized fuel from the feed pump, further pressurizing the fuel and supplying it to a rail of the Common Rail system, a shared driving means for operatively driving both the feed pump and the high pressure pumping unit, and a flow regulator for controlling the fuel flow which will be pressurized into the rail and the fuel pumping procedure.
The high pressure pump assembly may further comprise an overflow valve, which discharges a portion of the fuel from the high pressure pumping unit when the fuel pressure in the high pressure pump assembly exceeds an upper limit.
The high pressure pumping unit may comprise only one piston type high pressure pump, and the driving means is a camshaft formed with only one cam for operatively driving the piston of the pump.
Alternatively, the high pressure pumping unit comprises at least two piston type inline high pressure pumps, and the driving means is a camshaft formed with cams for operatively driving the pistons of the pump, each cam corresponding to one of the pistons.
The or each high pressure pump may comprise a main body fixed in the casting and defining a piston chamber in which the piston moves reciprocately, an inlet valve allowing the pre-pressurized fuel to be drawn into the piston chamber, and an outlet valve allowing the fuel that has been drawn into the piston and has been further pressurized by the piston to be discharged into the rail, each of the inlet and outlet valves being a check valve, preferably, a ball/conus or flat type of check valve. The or each cam may comprise one, two or more cam lobes which are spaced around the axis of the camshaft by equal angular displacement.
If at least two inline high pressure pumps are provided, the corresponding cams are preferably regularly shifted in a circumferential direction with respect to each other around the axis of the driving shaft.
Preferably, the camshaft is driven by an output of an engine which is supplied with fuel by the Common Rail system.
Preferably, the feed pump is a blade type pump comprises blades driven by the camshaft in rotation. Other types of feed pump may also be used here, for example gear pumps, or electrical feeding pumps.
The feed pump has an inlet coupling for connecting with the fuel reservoir, and the inlet coupling may be sealed by a removable sealing cap when the high pressure pump assembly is not assembled.
According to the present invention, the feed pump, the high pressure pumping unit and the fuel flow regulator are integrated together by the single casting to form a high pressure pump assembly for Common Rail system. Meanwhile, the feed pump and the high pressure pumping unit are driven by the same driving means. Thus, the integrated high pressure pump assembly is compact and simple, and thus is cost-effective.
Brief Description of the Drawings
The foregoing and other aspects of the invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the following drawings, in which:
Fig. 1 is a cross sectional front view of a high pressure pump assembly of the invention;
Fig. 2 is a cross sectional side view of the high pressure pump assembly of Fig. 1 ;
Fig. 3 is a cross sectional front view of a part of a high pressure pumping unit used in the high pressure pump assembly of Fig. 1.
Fig. 4 is a cross sectional front view of a feed pump used in the high pressure pump assembly of Fig. 1; and
Fig. 5 is a cross sectional side view of the feed pump of Fig. 4.
Detailed Description of the Preferred Embodiments
Fig. 1 shows a general arrangement of an embodiment of a high pressure pump assembly of the invention. The high pressure pump assembly forms a component of a Common Rail system for supplying high pressure fuel into a rail (not shown), which in turn injects fuel via injectors into an engine (not shown).
As can be seen, the high pressure pump assembly comprises a feed pump 1, a high pressure pumping unit 2, a fuel flow regulator 3 and a overflow valve 4, all of them being integrated together by a casting 5.
The casting 5 comprises a first housing part 51 defining a first main cavity extending in an transverse direction (left-right direction in Fig. 1), a second housing part 52 defining a second main cavity extending in a longitudinal direction perpendicular to the transverse direction and opening into the first main cavity, and a supplementary attaching part 53 formed on a side of the second housing part 52 and defining a first supplementary cavity opening into the second main cavity and extending perpendicularly to the second main cavity, preferably in the transverse direction, i.e., parallel to the first main cavity, and a second supplementary cavity communicating with the first supplementary cavity via a through hole and extending perpendicularly to the first supplementary cavity, preferably in the longitudinal direction, i.e., parallel to the second main cavity.
The feed pump 1 may have a conventional structure and is mounted to a first end of the generally cylindrical first housing part 51. The fuel flow regulator 3 and the overflow valve 4 may each have a conventional structure and are mounted to the supplementary attaching part 53 communicating with the first and second supplementary cavities respectively. In the embodiment shown in Fig. 1 , the feed pump 1 is a blade pump driven by a driving shaft 10 which also drives the high pressure pumping unit 2. The driving shaft 10 is mounted through the first main cavity in the transverse direction and is rotatably supported near its opposite ends via bearings 14. Both ends of the driving shaft 10 protrude out from the first housing part 51. One end 12 of the driving shaft 10 is a feed pump driving end for operatively driving the blades of the feed pump in rotation and is supported via one of the bearings 14 by one end of the first housing part 51. The other end 15 of the driving shaft 10 is a driven end to be driven in rotation by an output of the engine, preferably via a transmission mechanism such as a gear, belt mechanism or Oldham coupling. The other end 15 of the driving shaft 10 is supported via the other bearing 14 by an end cap 74 fixed to the other end of the first housing part 51. Between the opposite ends of the driving shaft 10 is at least one cam 16 formed integrally on the shaft.
As shown in Fig. 2, a lubricant port 80 is formed at an upper portion of the first housing part 51 , for injecting lubricant into the first main cavity defined in the first housing part 51 to lubricate the moving parts of the high pressure pump assembly, including the driving shaft 10 and corresponding bearings, the roller type driving means 44 and the pistons 30. The lubricant port 80 is sealed by a lubricant port cap 82 which is removed for connecting the pump to the lubrication system of the engine.
The high pressure pumping unit 2 is mounted in the casting 5 and comprises at least one high pressure pump 20 operatively driven by the driving shaft 10. The or each high pressure pump 20 is a piston pump driven by a corresponding cam 16 of the driving shaft 10. The number of the high pressure pump(s) 20 corresponds to the number of the cam(s) 16. In the embodiment shown in Fig. 1, two high pressure pumps 20 are provided and are driven by two cams 16 of the driving shafts 10 respectively. The two cams 16 are formed at axial locations on the driving shaft 10 corresponding to the high pressure pumps 20 and are angularly shifted in a circumferential direction with respect to each other, at different angles, in this case preferable by 90deg., around the axis of the driving shaft. Each cam 16 has a earning surface with at least one cam lobe, actually preferably two, as shown which are spaced with each other by different angles, actually preferably by 180deg. around the axis of the driving shaft. In the actual case,(cam with 2 lobes, spaced with each other at 180deg.) when the driving shaft 10 rotates one turn, each cam 16 drives the high pressure pump 20 to operate twice, and when one high pressure pump operates to draw in fuel, the other high pressure pump operates to expel out fuel, as later described in details.
If the high pressure pumping unit 2 comprises only one high pressure pump 20, then the rail will be supplied with fuel with fluctuated pressure. Thus, providing several high pressure pumps 20 may reduce the pressure fluctuation in the rail. Generally speaking, according to the present invention, when several high pressure pumps 20 are provided, corresponding number of cams are formed on the driving shaft 10 and are regularly shifted in a circumferential direction with respect to each other around the axis of the driving shaft. Each cam 16 may have one or more cam lobes, preferably two cam lobes. The cam lobes are equally spaced around the axis of the driving shaft.
In the embodiment shown in Fig. 1, the second main cavity of the second housing part 52 is divided into two sub-cavities, each high pressure pump 20 being accommodated in one of the sub-cavities. Each high pressure pump 20 comprises a main body 22 arranged in the sub-cavity and is fixed to the second housing part 52 by screws inserted through through-holes 26 (see Fig.3) formed in a flange 24 of the main body 22. The inner part (the part facing the driving shaft) of main body 22 is formed with a cylindrical piston chamber 28 for receiving a piston 30, and the outer part (the part facing outside) of main body 22 is formed with a valve cavity for receiving a inlet valve 32 and an outlet valve 34. The axis of the piston chamber intersects with and is perpendicular to the axis of the driving shaft 10, thus the piston 30 may reciprocate within the piston chamber in a direction perpendicular to the axis of the driving shaft 10. The piston 30 has a driving end protruding out from the piston camber and connected with a roller type driving means 44 which is biased by a spring 46 against the earning surface of the cam 16. Thus, when the driving shaft 10 rotates, the earning surface of the cam 16 drives the piston 30 via the roller type driving means 44 so that the piston 30 reciprocates in the piston chamber 28.
Each of the inlet valve 32 and the outlet valve 34 is a check valve. In the embodiment shown in Figs. 1 to 3, especially in Fig. 3, they are each a ball type check valve comprising a valve ball as a controlling element. The valve ball is normally biased by a spring, means to block the flow passage way in the valve until a certain pressure is reached; also other types of check valves may also be used. The inlet valve 32 is arranged between and communicates with the piston chamber 28 and the outlet valve 34. The outlet valve 34 is fixed in the main body 22, preferably by screws. The inlet valve 32 is clamped between the outlet valve 34 and the inner part of main body 22 by the outlet valve 34.
The outlet valve 34 has an outlet coupling 36 for attaching a high pressure supply line leading to the rail.
In the embodiment shown in Fig. 3, the inlet valve 32 comprises two valve bodies, i.e., a first valve body holding a spring type ball-biasing means and a valve ball 40 and a second valve body formed with an inner passage way 39 as well as a valve seat against which the valve ball 40 is pushed by the spring type ball-biasing means of the inlet valve. The outlet valve 34 comprises a single valve body, holding a spring type ball-biasing means and a valve ball 42. The outer end of the first inlet valve body is shown as formed with a valve seat against which the valve ball 42 of the outlet valve is pushed by the spring type ball-biasing means of the outlet valve.
When the piston 30 (Fig. 1) moves towards the driving shaft to create a negative pressure in the piston chamber 28, fuel is drawn into the inlet valve 32 through an inlet port 38 (Fig. 3) formed through the outer part of main body 22 and the inner passage way 39 of the inlet valve 32, and can not push up the valve ball 40 against the biasing force of the spring type ball of the inlet valve, and therefore flows only into the piston chamber 28. During this period, the outlet valve 34 is closed by its valve ball 42, and thus the high pressure fuel in the rail cannot flow back through the outlet valve 34.
On the other hand, when the piston 30 moves away from the driving shaft to create a positive pressure in the piston chamber 28, the fuel in the piston chamber is pressurized and forced out from the piston chamber through a channel 41, flows through the inlet valve 32, pushes up the valve ball 42 against the biasing force of the spring type ball of the outlet valve, and then flows towards the rail via the outlet coupling 36. During this period, the inlet is closed by its valve ball 40, and thus the fuel in the piston chamber cannot flow back through inlet port 38.
As shown in Figs. 4 and 5, the feed pump 1, which feeds fuel from a fuel reservoir (not shown) and pre-pressurizes the fuel, has an inlet port 62 for drawing fuel into the feed pump, blades 64 for moving and pre-pressurizing the fuel in the feed pump, and an outlet port 66 for discharge the pre-pressurized fuel from the feed pump. The inlet port 62 is connected with the fuel reservoir via an inlet coupling 72 and a feed line (not shown). The outlet port 66 is connected with the inlet port 38 for the inlet valve 32 via an inner duct 68 formed in the casting 5 from Fig.l. Thus, fuel is drawn from the fuel reservoir and is pre-pressurized by the feed pump l(Fig.4, Fig.5), and then the pre-pressurized fuel is supplied to the high pressure pumping unit 2 (Fig.l) to be further pressurized and supplied to the common at a high pressure, up to 2,000 bars.
The inlet coupling 72 of the feed pump 1 is to be connected with the fuel reservoir via the feed line mentioned above. When the high pressure pump assembly is not assembled in the fuel injection system, the inlet coupling 72 is not connected with the feed line. Thus, the inlet coupling 72 should be sealed to keep any foreign material from coming into the feed pump 1. To this end, a removable sealing cap 70 is attached to the inlet coupling 72. As a result, when the high pressure pump assembly is transported and handled, the feed pump 1 is protected by the removable sealing cap 70. When the high pressure pump assembly is to be assembled into the fuel injection system the removable sealing cap 70 is removed and the inlet coupling 72 is connected to the feed line.
Meanwhile, when the high pressure pump assembly is not assembled in the fuel injection system, the driven end 15 of the driving shaft 10 is protected with a removable shaft-end sealing cap 90 to protect the exposed driven end 15. The removable shaft-end sealing cap 90 is temporarily attached to the driven end 15 by a screw 92.
The flow regulator 3 may be a conventional one, which controls the high pressure in the rail as well as the fuel pumping procedure.
The overflow valve 4 (Fig.l) may also be a conventional over-pressure protection valve. In the condition that the fuel pressure inside the high pressure pump assembly exceeds an upper limit, the overflow valve 4 acts to discharge a portion of the fuel from the high pressure pump assembly. The fuel discharged from the overflow valve 4 flows back to the fuel reservoir.
According to the present invention, the feed pump, the high pressure pumping unit and the flow regulator are integrated together by the single casting to form a high pressure pump assembly for Common Rail system. Meanwhile, the feed pump and the high pressure pumping unit are driven by the same driving means. Thus, the integrated high pressure pump assembly is compact and simple, and thus is cost-effective.
Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.

[gmcsmoke]

Stop quoting novels when responding to posts.

Chripes that's annoying as posting broken links.

[FishOnOne]

Turtle n Peeps wrote:

Is Ford finding it a bit too hot in the Diesel Common Rail Fuel System?

I wonder how many engines Ford manufacture that needs a Common Rail Diesel Fuel Cooling System?

The patent was just filed October 28, 2010....

When did the first 6.7 hit the streets?

Was this based on their first year analysis of issues, or was this system implemented in the 6.7?

How is fuel cooled in the 6.7?

WTH is this all about? :h

It's cooled with a fuel cooler in a seperate cooling system. Gesuss. :S

The fuel is cooled in a 6.4 psd to help with fuel effiency, which is ironic because the 6.4 is anything but fuel efficient.

[Turtle_n_Peeps]

Is Ford finding it a bit too hot in the Diesel Common Rail Fuel System?

I wonder how many engines Ford manufacture that needs a Common Rail Diesel Fuel Cooling System?

The patent was just filed October 28, 2010....

When did the first 6.7 hit the streets?

Was this based on their first year analysis of issues, or was this system implemented in the 6.7?

How is fuel cooled in the 6.7?

WTH is this all about? :h

It's cooled with a fuel cooler in a seperate cooling system. Gesuss. :S

[FishOnOne]

NewsW wrote:
Is Ford finding it a bit too hot in the Diesel Common Rail Fuel System?

I wonder how many engines Ford manufacture that needs a Common Rail Diesel Fuel Cooling System?

The patent was just filed October 28, 2010....

When did the first 6.7 hit the streets?

Was this based on their first year analysis of issues?

------------------

Diesel fuel cooling system and control strategy
Timothy Chyo et al

Patent number: 8006675
Filing date: Oct 28, 2010
Issue date: Aug 30, 2011
Application number: 12/914,913


A method is described for cooling fuel for a diesel engine system with a common rail fuel injection system having a coolant pump and a fan. The method comprises passing a returning fuel from the engine through a fuel to coolant heat exchange system to cool the fuel, and adjusting the cooling of the fuel by controlling the coolant pump and/or the engine cooling fan.

Inventors: Timothy Chyo, Peter Kanefsky, Carlos Armesto, Anil Shah, Douglas Schoen

Original Assignee: Ford Global Technologies, LLC
Primary Examiner: M. McMahon

Attorneys: Julia Voutyras, Alleman Hall McCoy Russell & Tuttle LLP
Current U.S. Classification: 123/541; 123/514


Claims

1. A fuel cooling system for a diesel internal combustion engine system having a set of engine cylinders, a fuel storage tank, and a common rail fuel injection system comprises:

a fuel distribution circuit for carrying fuel from the fuel storage tank to the engine cylinders;

a fuel recycling circuit for recycling un-injected fuel;

a temperature sensor for sensing fuel temperature;

a fuel to coolant heat exchange system for cooling the fuel wherein the fuel to coolant heat exchange system comprises a coolant reservoir, an electric coolant pump, and a heat exchange manifold;
a mechanism for controlling the electric coolant pump operation;
an air to coolant heat exchange system coupled to the fuel to coolant heat exchange system for cooling the coolant in the fuel to coolant heat exchange system wherein the air to coolant heat exchange system is exposed to vehicle ram air and includes a heat exchange manifold and a cooling fan; and
a mechanism for controlling the cooling fan.

2. A fuel cooling system according to claim 1 wherein the control mechanism for controlling the cooling adjusts speed of the cooling fan.

3. A fuel cooling system according to claim 1 wherein the cooling fan is an engine cooling fan coupled to an engine radiator for cooling engine coolant.

4. A fuel cooling system according to claim 1 further comprising a plurality of temperature sensors at multiple locations along a fuel flow path.

5. A fuel cooling system according to claim 1 further comprising a pressure regulator regulating fuel pressure.

6. A fuel cooling system according to claim 5 wherein the pressure regulator provides directs fuel from a high pressure fuel line to a back flow fuel line of the recycling fuel circuit.

7. A fuel cooling system according to claim 1 wherein the fuel recycling circuit recycles un-injected fuel back to the fuel storage tank.

8. A fuel cooling system according to claim 1 wherein the fuel recycling circuit recycles un-injected fuel back to the common rail fuel injection system without first passing through the fuel storage tank.

9. A fuel cooling system according to claim 1 wherein the fuel to coolant heat exchange system is positioned in the route of un-injected fuel returning from the common rail fuel injection system.


--------------------


BACKGROUND AND SUMMARY

Common rail diesel fuel injection systems have enable diesel engines to operate with increased fuel efficiency, reduced noise, and reduced emissions. The common rail diesel injection system first pressurizes fuel under high pressure in a central accumulator rail and then delivers it to the individual electronically-controlled injection valves/injectors. The pressurized fuel is used for combustion and injector operation. In addition, fuel is also used to cool and lubricate the pumping apparatus. This provides high injection pressures, in some cases over 25,000 psi, across a wide range of operating conditions. The common rail injection system may allow up to 5 injections per engine cycle. However, one issue associated with the common rail fuel injection system is the amount of heat added to the fuel not used for combustion. The unburned/return fuel temperature can reach up to 140.degree. C., for example. The elevated fuel temperature may cause deterioration of the fuel pump efficiency and durability, degradation of plastics and elastomers, and require hydrocarbon traps in the fuel system. Various cooling systems may be used to cool the returning fuel to address the above issues.

One such fuel cooling system for diesel injection system is described in U.S. Pat. No. 6,868,838. This system includes two cooling devices for cooling un-injected fuel returning from the common rail fuel injection system to the fuel tank. The first cooling device (a water/fuel exchanger) is positioned downstream of the engine; and the second cooling device (an air/fuel exchanger) is positioned downstream of the first cooling device. A control device controls the position of the various valves in the cooling system to determine the returning fuel flow route. The returning fuel can either pass through or bypass any one of the cooling devices depending on the valve positions. This results in various degrees of fuel cooling. The control device controls the valve based on the ambient temperature and the engine speed. For example, at a low ambient temperature, on the order of -20.degree. C., and a medium engine speed, since no cooling of the fuel is required, the control unit directs the valves to be in such positions that returning fuel bypasses both cooling devices. Likewise, at a very high exterior temperature, on the order of 80.degree. C., and high engine speed, since maximum cooling of the returning fuel is needed, the control unit directs the valves to be in such positions that the returning fuel passes through both cooling devices. Further, at a hot ambient temperature, on the order of 40.degree. C., and a low engine speed, since moderate cooling of the returning fuel is needed, the control unit directs the valves to be in such positions that the returning fuel bypasses the first cooling device but passes through the second cooling device.

However, the inventors herein have recognized several issues with the above approach. For example, the use of two cooling devices in combination with multiple control valves may increase a likelihood of mechanical or electrical degradation of the system, and thus during some conditions inadequate cooling may result. Further, it may be difficult to control the returning fuel temperature with sufficient accuracy through coordination of the different valve positions.

The inventors herein have recognized that such issues may be at least partially addressed by providing a fuel cooling system for a diesel engine system having a set of internal combustion cylinders, a fuel storage tank, and a common rail fuel injection system which comprises (1) a fuel distribution circuit for carrying fuel from the fuel storage tank to the common rail fuel injection system to be injected into the engine cylinders; (2) a fuel recycling circuit for carrying un-injected fuel returning from the common rail fuel injection system back to the fuel storage tank; (3) a temperature sensor for sensing fuel temperature; (4) a fuel to coolant heat exchange system for cooling the fuel wherein the fuel to coolant heat exchange system comprises a coolant reservoir, an electric coolant pump, and a heat exchanger; (5) a mechanism for controlling the electric coolant pump operation; (6) an air to coolant heat exchange system coupled to the fuel to coolant heat exchange system for cooling the coolant in the fuel to coolant heat exchange system wherein the air to coolant heat exchanger system is exposed to vehicle ram air and includes a heat exchanger and a cooling fan; (7) and a mechanism for controlling the cooling fan.

In some embodiments, the control mechanisms for controlling the coolant pump and the cooling fan may be provided by a control system, such as an engine control unit, where control of the pump and cooling fan may vary with operating conditions of the vehicle.

In some embodiments, it is possible the fuel cooing system may contain a routine for performing temperature sensor diagnostics. In some other embodiments, the fuel cooling system may further be able to switch to a temperature sensor degradation strategy for controlling the coolant pump and/or for controlling the cooling fan in case the temperature sensor is not working properly.

By providing both an air to coolant heat exchange system in addition to a fuel to coolant heat exchange system, the fuel cooling system may achieve additional cooling that may not be possible through a fuel to coolant heat exchange system alone. Further, by coordinating control of the cooling fan and cooling pump, appropriate cooling can be tailored to the vehicle operating conditions to achieve improved fuel cooling and performance. For example, the fuel cooling system may provide an supplemental cooling when the vehicle ram air is not sufficient, for example when the vehicle is operating at an lower engine speed or when the vehicle ram air is impeded by for example a physical block.

Finally, by providing a fuel temperature sensor degradation strategy, the fuel cooling system may reduce fuel system shut-downs and provide necessary cooling even when the fuel temperature sensor degrades.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system diagram of an example fuel cooling system.

FIG. 2 is another system diagram of an example fuel cooing system.

FIG. 3 is a flowchart illustrating selection of whether to run a temperature sensor degradation strategy or a normal control strategy.

FIG. 4 is a flowchart showing a coolant pump control strategy.

FIG. 5 is a flowchart showing a engine fan control strategy.

FIG. 6 is a flowchart showing a temperature sensor degradation strategy for controlling a coolant pump.

FIG. 7 is a flowchart showing a temperature sensor degradation strategy for controlling a cooling fan.

FIG. 8 is a flowchart showing a torque truncation operation.

DETAILED DESCRIPTION

FIG. 1 shows an example fuel cooling system for a diesel engine system having a set of internal combustion engine cylinders 100; a fuel storage tank 102 for storing fuel; a fuel distribution circuit 104, a common rail fuel injection system 106, a fuel recycling circuit 108, a temperature sensor 110, a fuel to coolant heat exchange system 112, an air to coolant heat exchange system 114, an engine control unit 116, pressure sensors 118, various sensors 120, and various actuators 122.

In this example embodiment, the fuel flows out of the fuel storage tank 102, passes through the fuel distribution circuit 104, and passes through the common rail fuel injection system 106. From the common rail fuel injection system 106, the fuel then flows into the engine cylinders 100 to be injected via injectors (not shown). The un-injected fuel travels from the common rail fuel injection system 106, passing through the fuel recycling circuit 108, and then back to the fuel storage tank 102. The fuel to coolant heat exchange system 112 is positioned in the path of the fuel recycling circuit 108 for cooling the un-injected fuel returning to the fuel storage tank 102 and is coupled to and cooled by the air to coolant heat exchange system 114.

The temperature sensor 110 is positioned in the path of the fuel recycling circuit 108 for sensing fuel temperature. The pressure sensors 118 are positioned in the fuel distribution circuit 104 and the common rail fuel injection system 106. The engine control unit 116 is coupled to the temperature sensor 110, pressure sensors 118, the fuel to coolant heat exchange system 112, the air to coolant heat exchange system 114, and to various other sensors 120 and actuators 122 (not shown) In this embodiment, still referring to FIG. 1, the fuel storage tank 102 has a first opening which provides a passage for fuel in the fuel storage tank 102 to flow into the low pressure fuel line 104b of the fuel distribution circuit 104; has a second opening which provides a passage for fuel returning from the back flow fuel line 108a of the fuel recycling circuit 108.

Although the fuel storage tank 102 may have an opening for receiving the un-injected fuel from the common rail fuel injection system 106 through the fuel recycling circuit 108, it is possible in other embodiments the fuel flow path is such that the un-injected fuel does not return back to the fuel storage tank, for example, the un-injected fuel instead may be recycled directly back to the common rail fuel injection system 106. Also, the fuel storage tank may have an opening and/or a mechanism for receiving excess fuel back from the fuel distribution circuit, for example, when the engine is idling or is operating at a low speed so that the fuel delivered from the fuel storage tank 102 to the fuel distribution circuit 104 is excessive to what is required to drive the engine cylinders. In this way, the fuel is re-circulated back to the fuel storage tank 102 from the fuel distribution circuit 104 through, for example, a pressure regulator.

The fuel distribution circuit 104 includes a low pressure fuel pump 104a for pumping fuel out of the fuel storage tank 102; a low pressure fuel line 104b for carrying low pressure fuel coming out of the fuel storage tank 102; and a fuel filter 104c positioned in the path of the low pressure fuel line 104b for filtering the fuel. As mentioned before, in some embodiments, it is possible for the fuel distribution circuit 104 to have a mechanism to return excessive fuel back to the fuel storage tank 102. It may also be possible in some embodiments for the fuel distribution circuit 104 to include various pumps, filters, regulators, bypasses, valves, meters, sensors, controls, actuators, etc.

The common rail fuel injection system 106 is coupled on one end to the fuel distribution circuit 104 and on the other end to the engine cylinders 100 and the fuel recycling circuit 108. Injection system 106 includes a high pressure fuel pump 106a for pressurizing the fuel in the common rail fuel injection system 106 and a high pressure fuel line 106b for carrying the pressurized fuel to a common rail 106c in which the pressurized fuel is to be stored. Injection system 106 also includes a pressure regulator 106d, which is positioned between the high pressure fuel 106b and the backflow fuel line 108a for adjusting the fuel pressure in the high pressure fuel line 106b. Further, the common rail fuel injection system 106 includes fuel injectors 106e for injecting pressurized fuel into the engine cylinders 100. It is also possible to have other configurations of the common rail fuel injection system 106. For example, the common rail fuel injection system may include additional pressure and/or temperature sensors for sensing fuel pressure and temperature, may include additional pressure regulators for controlling the fuel pressure, and may include mechanisms for controlling fuel injection into the engine cylinders.

The fuel recycling circuit 108 receives un-injected fuel from the fuel injector 106e and returns the un-injected returning fuel back into the fuel storage tank 102. Fuel recycling circuit 108 also includes a fuel back flow line 108a for carrying the un-injected fuel. The fuel recycling circuit 108 is further coupled to the high pressure fuel line 106b of the fuel distribution circuit 106 via a pressure regulator 106d. The pressure regulator 106d may include one or more valves/mechanisms for fuel in the high pressure fuel line 106b to flow to the back flow fuel line 108a under certain conditions. For example, when the fuel pressure is too high in the high pressure fuel line 106b, the valves/mechanisms of the pressure regulator 106d will allow the fuel to flow from the high pressure fuel line 106b to the back flow fuel line 108a.

Although in this embodiment there is only one line, the back flow fuel line 108a, provided for the fuel recycling circuit, multiple lines may be provided. Also, the recycling circuit may be configured in such a way that it may receive recycling fuel from the fuel distribution circuit 104, for example. It is also possible, as mentioned before in reference to the fuel storage tank configuration, that the fuel recycling circuit 108 may not serve to return the un-injected fuel back from the common rail fuel injection system 106 to the fuel storage tank 102, but instead the fuel recycling circuit 108 serves to recycle the un-injected fuel directly back to the common rail fuel injection system 106. Further still, the fuel recycling circuit 108 may serve to return part of the un-injected fuel back to the fuel storage tank 102, and the other part of the un-injected fuel directly back to the common rail fuel injection system 106.

The fuel to coolant heat exchange system 112 may be positioned in the path of the fuel back flow line 108a of the fuel recycling circuit 108 for cooling the returning fuel from the common rail fuel injection system 106. The coolant heat exchange system 112 may include a coolant reservoir 112a for storing coolant in the fuel to coolant heat exchange system 112, a coolant pump 112b for pumping coolant in the fuel to coolant heat exchange system 112, and a fuel to coolant heat exchanger 112c for exchange heat between the returning fuel in the fuel back flow line 108a and the coolant in the fuel to coolant heat exchanger 112c. The coolant circulates in the fuel to coolant heat exchange system 112 for cooling the fuel. Although in this embodiment only one fuel to coolant heat exchange system is provided multiple fuel to coolant heat exchange systems may be provided. It is also possible to position one or more fuel to coolant heat exchange systems in the fuel distribution circuit. Although in this embodiment only one fuel to coolant heat exchange system is coupled to one air to coolant heat exchange system, in other embodiments other arrangements may provide adequate cooling of the fuel. For example, one fuel to coolant heat exchange system may be coupled to multiple air to coolant heat exchange systems, or multiple fuel to coolant heat exchange systems may be coupled to multiple air to coolant heat exchange systems, etc.

The air to coolant heat exchange system 114 may be coupled to the fuel to coolant heat exchange system 112. The air to coolant heat exchange system 114 may include an air to coolant heat exchanger 114a, vehicle ram air 114b, and a cooling fan 114c. The air to coolant heat exchanger 114a serves to exchange heat between air and the coolant. Airflow (as indicated by the dotted lines) may be used to cool the coolant. Airflow 114d may be created by the vehicle ram air 114b when vehicle is moving and/or airflow 114e may be created by an cooling fan 114c when the cooling fan 114c is turned on. As discussed previously in reference to the fuel to coolant heat exchange system of FIG. 1, in some embodiments, it may be possible to have other arrangements of the air to coolant heat exchange system. For example, several air to coolant heat exchange systems may be coupled to a fuel to coolant heat exchange system, etc.

The cooling fan 114c may is coupled to the engine and/or radiator, and may also circulate air through the radiator to cool engine coolant, as is in this embodiment, or it may be a separate fan. If the cooling fan adjusts flow through the radiator, the fan speed and operation may also be adjusted in response to engine temperature, such as based on engine coolant temperature, radiator temperature, etc.

The pressure sensors 118 are positioned in the low pressure line 104b and the common rail 106a of the common rail fuel injection system 106 for sensing fuel pressures at those locations. It is possible in other embodiments that no pressure sensor may be used, or multiple pressure sensors located at various positions may be included, and one or more other types of sensors, such as vehicle speed sensor, may also be included.

The temperature sensor 110 is positioned in the back flow fuel line 108a for sensing the fuel temperature of the returning fuel returning from the common rail fuel injection system 106. In this embodiment, the temperature sensor is coupled to the engine control unit 116. The temperature sensor may be positioned in other positions along the fuel path. Further, multiple temperature sensors located at various locations may be used. For example, the sensors may be positioned at various locations along the fuel path, at various locations along the coolant path, at various locations in the air to coolant heat exchange system, in the engine cylinders, etc. It is also possible in other embodiments for the temperature sensor to be physically disconnected from the engine control unit, for example, it is possible for the temperature sensor to communicate with the engine control unit via a wireless mean, such as infrared signal.

In this embodiment, only one pressure regulator 106d is positioned between the high pressure fuel line and the back flow fuel line 108a of the fuel recycling circuit 108; however it is possible to have several pressure regulators located at various positions of the fuel cooling system for regulating fuel pressure.

The engine control unit 116 is coupled to the temperature sensor 110, the coolant pump 112b, and the cooling fan 114c, the pressure regulator 106d and to various other sensors 120 and various other actuators 122 (e.g., low pressure fuel pump 104a, the high pressure fuel pump 106a, the pressure sensors 118, which are not all shown). It is possible in some embodiments that the engine control unit is coupled to various other pumps, sensors, controls, throttles, valves, etc. Although in this embodiment only one coolant pump and one cooling fan is provided, multiple coolant pumps and/or multiple cooling fans may be provided.

FIG. 2 illustrates another example fuel cooling system for a diesel internal combustion engine system. The fuel cooling system may include a set of engine cylinders 200, a fuel storage tank 202 for storing fuel, a common rail fuel injection system 206, a fuel recycling circuit 208, temperature sensors 210, a fuel to coolant heat exchange system 212, an air to coolant heat exchange system 214, an engine control unit control unit 216, various sensors 220, and various actuators 222.

The fuel storage tank 202 has a first opening which provides a passage for fuel to flow into the fuel distribution circuit 204. It has a second opening which provides a passage for fuel to return from the fuel distribution circuit 204 under certain conditions.

The fuel distribution circuit 204 includes a chassis fuel pump/filter 204a for pumping fuel out of the fuel storage tank 202 and for pressurizing the fuel; a pressure regulator 204b for regulating the pressure of the pressurized fuel; a primary engine filter 204c for filtering the fuel prior to the fuel entering the common rail fuel injection system 206. It may also be possible in other examples for the fuel distribution circuit 204 to include various other pumps, filters, regulators, bypasses, valves, meters, sensors, controls, actuators etc.

The common rail fuel injection system 206 is coupled on one end to the fuel distribution circuit 204 and on a second end to the engine cylinders 200 and on a third end to the fuel recycling circuit 208. It is possible that the common rail fuel injection system 206 may include additional pressure and/or temperature sensors for sensing fuel pressure and temperature, and it may include additional pressure regulators for controlling the fuel pressure, and may include mechanisms for controlling fuel injection into the engine cylinders.

The fuel recycling circuit 208 is coupled on both ends to the common rail fuel injection system 206 and includes a recirculation filter 208a. On one end, the fuel recycling circuit 208 receives the un-injected fuel from the common rail fuel injection system 206; and on the other end, the fuel recycling circuit 208 recycles fuel back to the common rail fuel injection system 206.

The temperature sensors 210 are positioned in the path of the fuel recycling circuit 208 and in the fuel storage tank.

The fuel to coolant heat exchange system 212 is positioned in the path of the fuel recycling circuit 208 for cooling the un-injected fuel and it is coupled to and cooled by the air to coolant heat exchange system 214.

The air to coolant heat exchange system 214 is coupled to the fuel to coolant heat exchange system 212 for cooling the coolant in the fuel to coolant heat exchange system 212. The air to coolant heat exchange system 214 includes an air to coolant heat exchanger 214a, vehicle ram air 214b, and a cooling fan 214c. The air to coolant heat exchanger 214a serves to exchange heat between air and the coolant. Airflow (as indicated by the dotted lines) may be used to cool the coolant. Airflow 214d may be created by the vehicle ram air 214b when vehicle is moving and/or airflow 214e may be created by a cooling fan 214c when the cooling fan 214c is turned on.

The engine control unit 216 is coupled to the temperature sensors 210, the fuel to coolant heat exchange system 212, the air to coolant heat exchange system 214, and to various other sensors 220 and controls 222 (Not all shown).

The fuel in the storage tank 202 flows into the fuel distribution circuit 204, then into the common rail fuel injection system 206, and finally into the engine cylinders 200 to be injected. In addition, a passage is provided for fuel in the fuel distribution circuit 208 to flow back to the fuel storage tank 202. For example, when the engine is idling or is operating at a low speed so that the fuel delivered to the fuel distribution circuit 204 is excessive to engine requirements, the fuel is re-circulated back to the fuel storage tank 202 from the fuel distribution circuit 204 through a bypass, for example, a pressure regulator 204b (will be further described below) and/or a chassis fuel pump/filter 204a (will be further described below). The un-injected fuel of the common rail fuel injection system 206 is recycled back to the common rail fuel injection system 206 through the fuel recycling circuit 208, without first passing through the fuel storage tank 202. Although un-injected fuel does not flow from the common rail fuel injection system 206 back to the fuel storage tank 202, this may be possible in other embodiments, as illustrated in FIG. 1.

The various embodiments of the fuel cooling system as described in FIG. 1 and their advantages as discussed above in relation to FIG. 1 also apply here to FIG. 2.

Various modifications or adjustments may be made to the above example systems. For example, the fuel storage tank may have opening for receiving un-injected fuel from the common rail fuel injection system, and/or it may have an opening for receiving excess fuel back from the fuel distribution circuit. The fuel distribution circuit may include one or more temperature sensors, pressure sensors, and various other pumps, filters, bypasses, valves, meters, sensors, controls, actuators, etc. The fuel distribution circuit may include one or multiple lines. Further, the common rail fuel injection system may include one or more temperature sensors, pressure sensors, pressure regulators and various other pumps, filters, bypasses, valves, meters, sensors, controls, actuators, etc. Regarding the fuel recycling circuit, it may recycle the fuel back to the fuel storage tank and/or directly back to the common rail fuel injection system. The fuel recycling circuit may be coupled to one or more fuel to coolant heat exchange systems. The fuel recycling circuit may also contain one or more filters, pumps. The fuel recycling circuit may include one or multiple lines.

In one example, the cooling fan may be also be coupled to the engine radiator and used to circulate air through the radiator to cool engine coolant and/or the engine. Alternatively, the cooling fan may be a separate fan from the engine cooling fan and may be used to cool the coolant in the fuel to coolant heat exchange system without also cooling the engine or radiator/engine coolant. One or more fuel to coolant heat exchange systems may be provided. The fuel to coolant heat exchange system may be positioned in the fuel recycling circuit, and/or in the fuel distribution circuit, and/or in other locations along the fuel flow route. In addition, one or multiple fuel to coolant heat exchange systems may be provided. It may also be possible that one or multiple air to coolant heat exchange systems are coupled to a fuel to coolant heat exchange system.

The fuel cooling system may include no pressure sensor, one pressure sensor, or multiple pressure sensors. The pressure sensors may be located in various locations, such as in a common rail of the common rail fuel injection system, in the fuel tank, in a fuel injector, etc. The fuel cooling system may include one or more temperature sensors. The temperature sensors may be located at various locations for sensing temperature, such as in the fuel storage tank, in the fuel distribution circuit, in the common rail fuel injection system, in the fuel recycling circuit, etc.

The control unit may be an engine control unit or may be a unit separate from the engine control unit. It may be configured to send and receive information from various sensors, such as temperature sensors and pressure sensors. It may also be coupled to and control operation of various pumps, such as coolant pump, and various fans, such as engine cooling fan. It may be used to receive information from various other sensors, pumps, actuators and valves etc.

The specific routines described below in the flowcharts may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various acts or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. Although not explicitly illustrated, the illustrated acts or functions may be repeatedly performed depending on the particular strategy being used, during engine operation. Further, these figures may graphically represent code to be programmed into the computer readable storage medium in a controller or control system.

FIGS. 3-8 show high-level flowcharts of example routines for controlling fuel temperature that may be implemented in a vehicle control system, such as an engine control unit (ECU), or in a fuel cooling system, such as illustrated in FIGS. 1-2.

FIG. 3 shows a high-level flowchart of an example routine 300 for selection of a temperature sensor degradation strategy or a normal control strategy for fuel temperature control. Specifically, the routine illustrates selection of the strategy for controlling the fuel temperature in a fuel cooling system. First, the engine control unit (ECU) runs the basic input/output system (BIOS) and determines whether there is any indication of temperature sensor degradation, such as but not limited to short circuit to ground, short circuit to plus, or open loop during various vehicle operating conditions, such as key-on-engine-on (KOEO), key-on-engine-running (KOER), or continued engine operation (CONT); or whether there is any engine torque truncation performed due to fuel temperature too HIGH in 308. If the ECU determines there is temperature sensor degradation, or engine torque truncation has occurred due to excessive fuel temperature, the ECU turns on a Diagnostic Test Code (DTC) in 310. On the other hand, if the ECU does not sense any indication of temperature sensor degradation or engine truncation, then the ECU performs no additional action and a normal control strategy for controlling the fuel temperature is continued in 312. After the ECU turns on the Diagnostic Test Code (DTC) in 310, the ECU determines whether there is temperature sensor degradation in 314. If ECU determines that there is temperature sensor degradation, the ECU overrides the normal control strategy for fuel temperature control and runs the temperature degradation strategy (See FIGS. 6-7) for fuel temperature control in 316. On the other hand, if ECU determines that there is no temperature sensor degradation, the ECU performs no additional action and the normal control strategy (See FIGS. 4-5) for fuel temperature control is continued in 318.

FIG. 4 shows a high-level flowchart of an example routine for a normal coolant pump control strategy. First, the engine control unit determines whether the fuel temperature TFU is greater than a calibratable threshold A (e.g., around 50.degree. C.) in 400. If the engine control unit determines that TFU is greater than the threshold A, then the engine control unit turns on coolant pump in 410. On the other hand, if the engine control unit determines that TFU is not greater than the threshold A, then the engine control unit performs no additional action in 412 (or decreases the engine speed or torque).

FIG. 5 shows a high-level flowchart of an example routine for running a normal engine cooling fan control strategy. First, the engine control unit determines whether the fuel temperature TFU is both greater than a calibratable threshold B (e.g., around 70.degree. C.) and the vehicle speed (VS) is less than a calibratable threshold C in 500. If the engine control unit determines that both TFU is greater than the threshold B and VS is less than the threshold C, then the engine control unit controls the engine cooling fan based on TFU. For example, it may turn on or increase fan speed when TFU is greater than desired, and may turn off or decrease fan speed when TFU is less than desired. On the other hand, if the engine control unit determines that it is not true that both TFU is greater than the threshold B and VS is less than the threshold C, either because TFU is not greater than threshold B or because VS is not less than threshold C, then the engine control unit requests a minimum calibratable fan speed. For example, the minimum fan speed may be a calibratable minimum fan speed based on engine speed, FIG. 6 is a high-level flowchart showing an example routine for running a temperature sensor degradation strategy for controlling the coolant pump. Specifically, the ECU determines if both the fuel temperature sensor has degraded (e.g., through a routine as illustrated in FIG. 3) and the intake air temperature is greater than a calibratable threshold D in 600. If both the fuel temperature sensor has failed and the intake air temperature is greater than a calibratable threshold D, then the ECU turns on the coolant pump (or increases speed or torque of the coolant pump) in 610. Otherwise, if it is not true that both the fuel temperature sensor has degraded and the intake air temperature is greater than a calibratable threshold D, either because there is no temperature sensor degradation or because the intake air temperature is not greater than threshold D, then the ECU turns off the coolant pump (or decreases speed or torque of the coolant pump in 612

FIG. 7 is a high-level flowchart showing an example routine for a temperature sensor degradation strategy for controlling the engine cooling fan. Specifically, the ECU determines if both the fuel temperature sensor has degraded (e.g., through a routine as illustrated in FIG. 3) and the vehicle speed (VS) is less than a calibratable threshold E in 700. If both the fuel temperature sensor has failed and the VS is less than a calibratable threshold E, then the ECU controls the engine cooling fan based on engine speed by looking up a calibratable fan speed to engine speed table in 712. Otherwise, when either there is no fuel temperature sensor degradation or the VS is not less than the calibratable threshold E, then the ECU performs no action in 714.

If the fuel temperature sensor has degraded, the strategy infers the fuel temperature based on the inlet air temperature to determine whether to turn ON/OFF the coolant pump. The viscous fan provides additional cooling if the fuel temperature continues to rise with the coolant pump ON.

FIG. 8 is a flowchart showing an example routine for performing a torque truncation operation. Specifically, the engine control unit (ECU) determines whether the fuel temperature TFU is greater than a calibratable temperature threshold F (e.g., around 70.degree. C.) in 800. If TFU is greater than threshold F, then the ECU performs an engine torque truncation, for example through a fuel temperature sensor logic in 810. Otherwise, if TFU is not greater than threshold F, then the ECU performs no additional action in 812. If ECU performs an engine torque truncation in 810, the ECU then runs the diagnostic test code for the temperature sensors in 814. The engine torque may be truncated in a plurality of ways, such as reducing an amount of fuel injection, changing (e.g., delaying) injection timing, increasing throttling, and various others.

By providing a mechanism to independently control the coolant pump and the engine cooling fan, the fuel cooling system may have more latitude to more precisely control fuel temperature for particular operating conditions. For example, when the fuel temperature is above a certain calibratable threshold A, for example above around 50.degree. C., the engine control unit adjusts the coolant pump. When both the fuel temperature is above another calibratable threshold B, for example above around 70.degree. C., and the vehicle speed is less than a calibratable threshold C, the engine control unit controls the engine cooling fan based on the fuel temperature. Otherwise, the engine control unit controls the engine cooling fan to a min calibratable speed. Further, by providing a mechanism for performing engine torque truncation when the fuel temperature is excessively high, for example at above 105.degree. C., the fuel cooling system may be able to further control the returning fuel temperature. Finally, by providing a fuel temperature sensor degradation strategy in addition to a normal strategy, the fuel cooling system may still provide necessary cooling when the fuel temperature sensor degrades. And, by providing a diagnostic code for the fuel temperature sensor, the fuel cooling system may be able to timely detect any degradation of the fuel temperature sensor and run the fuel temperature sensor degradation strategy

The following claims particularly point out certain combinations and subcombinations regarded as novel and nonobvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.

So what does the copy and paste suggest Gearloose... I mean NW

Is there any notepad calculations going on?

[NewsW]

Is Ford finding it a bit too hot in the Diesel Common Rail Fuel System?

I wonder how many engines Ford manufacture that needs a Common Rail Diesel Fuel Cooling System?

The patent was just filed October 28, 2010....

When did the first 6.7 hit the streets?

Was this based on their first year analysis of issues, or was this system implemented in the 6.7?

How is fuel cooled in the 6.7?

------------------

Diesel fuel cooling system and control strategy
Timothy Chyo et al

Patent number: 8006675
Filing date: Oct 28, 2010
Issue date: Aug 30, 2011
Application number: 12/914,913


A method is described for cooling fuel for a diesel engine system with a common rail fuel injection system having a coolant pump and a fan. The method comprises passing a returning fuel from the engine through a fuel to coolant heat exchange system to cool the fuel, and adjusting the cooling of the fuel by controlling the coolant pump and/or the engine cooling fan.

Inventors: Timothy Chyo, Peter Kanefsky, Carlos Armesto, Anil Shah, Douglas Schoen

Original Assignee: Ford Global Technologies, LLC
Primary Examiner: M. McMahon

Attorneys: Julia Voutyras, Alleman Hall McCoy Russell & Tuttle LLP
Current U.S. Classification: 123/541; 123/514


Claims

1. A fuel cooling system for a diesel internal combustion engine system having a set of engine cylinders, a fuel storage tank, and a common rail fuel injection system comprises:

a fuel distribution circuit for carrying fuel from the fuel storage tank to the engine cylinders;

a fuel recycling circuit for recycling un-injected fuel;

a temperature sensor for sensing fuel temperature;

a fuel to coolant heat exchange system for cooling the fuel wherein the fuel to coolant heat exchange system comprises a coolant reservoir, an electric coolant pump, and a heat exchange manifold;
a mechanism for controlling the electric coolant pump operation;
an air to coolant heat exchange system coupled to the fuel to coolant heat exchange system for cooling the coolant in the fuel to coolant heat exchange system wherein the air to coolant heat exchange system is exposed to vehicle ram air and includes a heat exchange manifold and a cooling fan; and
a mechanism for controlling the cooling fan.

2. A fuel cooling system according to claim 1 wherein the control mechanism for controlling the cooling adjusts speed of the cooling fan.

3. A fuel cooling system according to claim 1 wherein the cooling fan is an engine cooling fan coupled to an engine radiator for cooling engine coolant.

4. A fuel cooling system according to claim 1 further comprising a plurality of temperature sensors at multiple locations along a fuel flow path.

5. A fuel cooling system according to claim 1 further comprising a pressure regulator regulating fuel pressure.

6. A fuel cooling system according to claim 5 wherein the pressure regulator provides directs fuel from a high pressure fuel line to a back flow fuel line of the recycling fuel circuit.

7. A fuel cooling system according to claim 1 wherein the fuel recycling circuit recycles un-injected fuel back to the fuel storage tank.

8. A fuel cooling system according to claim 1 wherein the fuel recycling circuit recycles un-injected fuel back to the common rail fuel injection system without first passing through the fuel storage tank.

9. A fuel cooling system according to claim 1 wherein the fuel to coolant heat exchange system is positioned in the route of un-injected fuel returning from the common rail fuel injection system.


--------------------


BACKGROUND AND SUMMARY

Common rail diesel fuel injection systems have enable diesel engines to operate with increased fuel efficiency, reduced noise, and reduced emissions. The common rail diesel injection system first pressurizes fuel under high pressure in a central accumulator rail and then delivers it to the individual electronically-controlled injection valves/injectors. The pressurized fuel is used for combustion and injector operation. In addition, fuel is also used to cool and lubricate the pumping apparatus. This provides high injection pressures, in some cases over 25,000 psi, across a wide range of operating conditions. The common rail injection system may allow up to 5 injections per engine cycle. However, one issue associated with the common rail fuel injection system is the amount of heat added to the fuel not used for combustion. The unburned/return fuel temperature can reach up to 140.degree. C., for example. The elevated fuel temperature may cause deterioration of the fuel pump efficiency and durability, degradation of plastics and elastomers, and require hydrocarbon traps in the fuel system. Various cooling systems may be used to cool the returning fuel to address the above issues.

One such fuel cooling system for diesel injection system is described in U.S. Pat. No. 6,868,838. This system includes two cooling devices for cooling un-injected fuel returning from the common rail fuel injection system to the fuel tank. The first cooling device (a water/fuel exchanger) is positioned downstream of the engine; and the second cooling device (an air/fuel exchanger) is positioned downstream of the first cooling device. A control device controls the position of the various valves in the cooling system to determine the returning fuel flow route. The returning fuel can either pass through or bypass any one of the cooling devices depending on the valve positions. This results in various degrees of fuel cooling. The control device controls the valve based on the ambient temperature and the engine speed. For example, at a low ambient temperature, on the order of -20.degree. C., and a medium engine speed, since no cooling of the fuel is required, the control unit directs the valves to be in such positions that returning fuel bypasses both cooling devices. Likewise, at a very high exterior temperature, on the order of 80.degree. C., and high engine speed, since maximum cooling of the returning fuel is needed, the control unit directs the valves to be in such positions that the returning fuel passes through both cooling devices. Further, at a hot ambient temperature, on the order of 40.degree. C., and a low engine speed, since moderate cooling of the returning fuel is needed, the control unit directs the valves to be in such positions that the returning fuel bypasses the first cooling device but passes through the second cooling device.

However, the inventors herein have recognized several issues with the above approach. For example, the use of two cooling devices in combination with multiple control valves may increase a likelihood of mechanical or electrical degradation of the system, and thus during some conditions inadequate cooling may result. Further, it may be difficult to control the returning fuel temperature with sufficient accuracy through coordination of the different valve positions.

The inventors herein have recognized that such issues may be at least partially addressed by providing a fuel cooling system for a diesel engine system having a set of internal combustion cylinders, a fuel storage tank, and a common rail fuel injection system which comprises (1) a fuel distribution circuit for carrying fuel from the fuel storage tank to the common rail fuel injection system to be injected into the engine cylinders; (2) a fuel recycling circuit for carrying un-injected fuel returning from the common rail fuel injection system back to the fuel storage tank; (3) a temperature sensor for sensing fuel temperature; (4) a fuel to coolant heat exchange system for cooling the fuel wherein the fuel to coolant heat exchange system comprises a coolant reservoir, an electric coolant pump, and a heat exchanger; (5) a mechanism for controlling the electric coolant pump operation; (6) an air to coolant heat exchange system coupled to the fuel to coolant heat exchange system for cooling the coolant in the fuel to coolant heat exchange system wherein the air to coolant heat exchanger system is exposed to vehicle ram air and includes a heat exchanger and a cooling fan; (7) and a mechanism for controlling the cooling fan.

In some embodiments, the control mechanisms for controlling the coolant pump and the cooling fan may be provided by a control system, such as an engine control unit, where control of the pump and cooling fan may vary with operating conditions of the vehicle.

In some embodiments, it is possible the fuel cooing system may contain a routine for performing temperature sensor diagnostics. In some other embodiments, the fuel cooling system may further be able to switch to a temperature sensor degradation strategy for controlling the coolant pump and/or for controlling the cooling fan in case the temperature sensor is not working properly.

By providing both an air to coolant heat exchange system in addition to a fuel to coolant heat exchange system, the fuel cooling system may achieve additional cooling that may not be possible through a fuel to coolant heat exchange system alone. Further, by coordinating control of the cooling fan and cooling pump, appropriate cooling can be tailored to the vehicle operating conditions to achieve improved fuel cooling and performance. For example, the fuel cooling system may provide an supplemental cooling when the vehicle ram air is not sufficient, for example when the vehicle is operating at an lower engine speed or when the vehicle ram air is impeded by for example a physical block.

Finally, by providing a fuel temperature sensor degradation strategy, the fuel cooling system may reduce fuel system shut-downs and provide necessary cooling even when the fuel temperature sensor degrades.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system diagram of an example fuel cooling system.

FIG. 2 is another system diagram of an example fuel cooing system.

FIG. 3 is a flowchart illustrating selection of whether to run a temperature sensor degradation strategy or a normal control strategy.

FIG. 4 is a flowchart showing a coolant pump control strategy.

FIG. 5 is a flowchart showing a engine fan control strategy.

FIG. 6 is a flowchart showing a temperature sensor degradation strategy for controlling a coolant pump.

FIG. 7 is a flowchart showing a temperature sensor degradation strategy for controlling a cooling fan.

FIG. 8 is a flowchart showing a torque truncation operation.

DETAILED DESCRIPTION

FIG. 1 shows an example fuel cooling system for a diesel engine system having a set of internal combustion engine cylinders 100; a fuel storage tank 102 for storing fuel; a fuel distribution circuit 104, a common rail fuel injection system 106, a fuel recycling circuit 108, a temperature sensor 110, a fuel to coolant heat exchange system 112, an air to coolant heat exchange system 114, an engine control unit 116, pressure sensors 118, various sensors 120, and various actuators 122.

In this example embodiment, the fuel flows out of the fuel storage tank 102, passes through the fuel distribution circuit 104, and passes through the common rail fuel injection system 106. From the common rail fuel injection system 106, the fuel then flows into the engine cylinders 100 to be injected via injectors (not shown). The un-injected fuel travels from the common rail fuel injection system 106, passing through the fuel recycling circuit 108, and then back to the fuel storage tank 102. The fuel to coolant heat exchange system 112 is positioned in the path of the fuel recycling circuit 108 for cooling the un-injected fuel returning to the fuel storage tank 102 and is coupled to and cooled by the air to coolant heat exchange system 114.

The temperature sensor 110 is positioned in the path of the fuel recycling circuit 108 for sensing fuel temperature. The pressure sensors 118 are positioned in the fuel distribution circuit 104 and the common rail fuel injection system 106. The engine control unit 116 is coupled to the temperature sensor 110, pressure sensors 118, the fuel to coolant heat exchange system 112, the air to coolant heat exchange system 114, and to various other sensors 120 and actuators 122 (not shown) In this embodiment, still referring to FIG. 1, the fuel storage tank 102 has a first opening which provides a passage for fuel in the fuel storage tank 102 to flow into the low pressure fuel line 104b of the fuel distribution circuit 104; has a second opening which provides a passage for fuel returning from the back flow fuel line 108a of the fuel recycling circuit 108.

Although the fuel storage tank 102 may have an opening for receiving the un-injected fuel from the common rail fuel injection system 106 through the fuel recycling circuit 108, it is possible in other embodiments the fuel flow path is such that the un-injected fuel does not return back to the fuel storage tank, for example, the un-injected fuel instead may be recycled directly back to the common rail fuel injection system 106. Also, the fuel storage tank may have an opening and/or a mechanism for receiving excess fuel back from the fuel distribution circuit, for example, when the engine is idling or is operating at a low speed so that the fuel delivered from the fuel storage tank 102 to the fuel distribution circuit 104 is excessive to what is required to drive the engine cylinders. In this way, the fuel is re-circulated back to the fuel storage tank 102 from the fuel distribution circuit 104 through, for example, a pressure regulator.

The fuel distribution circuit 104 includes a low pressure fuel pump 104a for pumping fuel out of the fuel storage tank 102; a low pressure fuel line 104b for carrying low pressure fuel coming out of the fuel storage tank 102; and a fuel filter 104c positioned in the path of the low pressure fuel line 104b for filtering the fuel. As mentioned before, in some embodiments, it is possible for the fuel distribution circuit 104 to have a mechanism to return excessive fuel back to the fuel storage tank 102. It may also be possible in some embodiments for the fuel distribution circuit 104 to include various pumps, filters, regulators, bypasses, valves, meters, sensors, controls, actuators, etc.

The common rail fuel injection system 106 is coupled on one end to the fuel distribution circuit 104 and on the other end to the engine cylinders 100 and the fuel recycling circuit 108. Injection system 106 includes a high pressure fuel pump 106a for pressurizing the fuel in the common rail fuel injection system 106 and a high pressure fuel line 106b for carrying the pressurized fuel to a common rail 106c in which the pressurized fuel is to be stored. Injection system 106 also includes a pressure regulator 106d, which is positioned between the high pressure fuel 106b and the backflow fuel line 108a for adjusting the fuel pressure in the high pressure fuel line 106b. Further, the common rail fuel injection system 106 includes fuel injectors 106e for injecting pressurized fuel into the engine cylinders 100. It is also possible to have other configurations of the common rail fuel injection system 106. For example, the common rail fuel injection system may include additional pressure and/or temperature sensors for sensing fuel pressure and temperature, may include additional pressure regulators for controlling the fuel pressure, and may include mechanisms for controlling fuel injection into the engine cylinders.

The fuel recycling circuit 108 receives un-injected fuel from the fuel injector 106e and returns the un-injected returning fuel back into the fuel storage tank 102. Fuel recycling circuit 108 also includes a fuel back flow line 108a for carrying the un-injected fuel. The fuel recycling circuit 108 is further coupled to the high pressure fuel line 106b of the fuel distribution circuit 106 via a pressure regulator 106d. The pressure regulator 106d may include one or more valves/mechanisms for fuel in the high pressure fuel line 106b to flow to the back flow fuel line 108a under certain conditions. For example, when the fuel pressure is too high in the high pressure fuel line 106b, the valves/mechanisms of the pressure regulator 106d will allow the fuel to flow from the high pressure fuel line 106b to the back flow fuel line 108a.

Although in this embodiment there is only one line, the back flow fuel line 108a, provided for the fuel recycling circuit, multiple lines may be provided. Also, the recycling circuit may be configured in such a way that it may receive recycling fuel from the fuel distribution circuit 104, for example. It is also possible, as mentioned before in reference to the fuel storage tank configuration, that the fuel recycling circuit 108 may not serve to return the un-injected fuel back from the common rail fuel injection system 106 to the fuel storage tank 102, but instead the fuel recycling circuit 108 serves to recycle the un-injected fuel directly back to the common rail fuel injection system 106. Further still, the fuel recycling circuit 108 may serve to return part of the un-injected fuel back to the fuel storage tank 102, and the other part of the un-injected fuel directly back to the common rail fuel injection system 106.

The fuel to coolant heat exchange system 112 may be positioned in the path of the fuel back flow line 108a of the fuel recycling circuit 108 for cooling the returning fuel from the common rail fuel injection system 106. The coolant heat exchange system 112 may include a coolant reservoir 112a for storing coolant in the fuel to coolant heat exchange system 112, a coolant pump 112b for pumping coolant in the fuel to coolant heat exchange system 112, and a fuel to coolant heat exchanger 112c for exchange heat between the returning fuel in the fuel back flow line 108a and the coolant in the fuel to coolant heat exchanger 112c. The coolant circulates in the fuel to coolant heat exchange system 112 for cooling the fuel. Although in this embodiment only one fuel to coolant heat exchange system is provided multiple fuel to coolant heat exchange systems may be provided. It is also possible to position one or more fuel to coolant heat exchange systems in the fuel distribution circuit. Although in this embodiment only one fuel to coolant heat exchange system is coupled to one air to coolant heat exchange system, in other embodiments other arrangements may provide adequate cooling of the fuel. For example, one fuel to coolant heat exchange system may be coupled to multiple air to coolant heat exchange systems, or multiple fuel to coolant heat exchange systems may be coupled to multiple air to coolant heat exchange systems, etc.

The air to coolant heat exchange system 114 may be coupled to the fuel to coolant heat exchange system 112. The air to coolant heat exchange system 114 may include an air to coolant heat exchanger 114a, vehicle ram air 114b, and a cooling fan 114c. The air to coolant heat exchanger 114a serves to exchange heat between air and the coolant. Airflow (as indicated by the dotted lines) may be used to cool the coolant. Airflow 114d may be created by the vehicle ram air 114b when vehicle is moving and/or airflow 114e may be created by an cooling fan 114c when the cooling fan 114c is turned on. As discussed previously in reference to the fuel to coolant heat exchange system of FIG. 1, in some embodiments, it may be possible to have other arrangements of the air to coolant heat exchange system. For example, several air to coolant heat exchange systems may be coupled to a fuel to coolant heat exchange system, etc.

The cooling fan 114c may is coupled to the engine and/or radiator, and may also circulate air through the radiator to cool engine coolant, as is in this embodiment, or it may be a separate fan. If the cooling fan adjusts flow through the radiator, the fan speed and operation may also be adjusted in response to engine temperature, such as based on engine coolant temperature, radiator temperature, etc.

The pressure sensors 118 are positioned in the low pressure line 104b and the common rail 106a of the common rail fuel injection system 106 for sensing fuel pressures at those locations. It is possible in other embodiments that no pressure sensor may be used, or multiple pressure sensors located at various positions may be included, and one or more other types of sensors, such as vehicle speed sensor, may also be included.

The temperature sensor 110 is positioned in the back flow fuel line 108a for sensing the fuel temperature of the returning fuel returning from the common rail fuel injection system 106. In this embodiment, the temperature sensor is coupled to the engine control unit 116. The temperature sensor may be positioned in other positions along the fuel path. Further, multiple temperature sensors located at various locations may be used. For example, the sensors may be positioned at various locations along the fuel path, at various locations along the coolant path, at various locations in the air to coolant heat exchange system, in the engine cylinders, etc. It is also possible in other embodiments for the temperature sensor to be physically disconnected from the engine control unit, for example, it is possible for the temperature sensor to communicate with the engine control unit via a wireless mean, such as infrared signal.

In this embodiment, only one pressure regulator 106d is positioned between the high pressure fuel line and the back flow fuel line 108a of the fuel recycling circuit 108; however it is possible to have several pressure regulators located at various positions of the fuel cooling system for regulating fuel pressure.

The engine control unit 116 is coupled to the temperature sensor 110, the coolant pump 112b, and the cooling fan 114c, the pressure regulator 106d and to various other sensors 120 and various other actuators 122 (e.g., low pressure fuel pump 104a, the high pressure fuel pump 106a, the pressure sensors 118, which are not all shown). It is possible in some embodiments that the engine control unit is coupled to various other pumps, sensors, controls, throttles, valves, etc. Although in this embodiment only one coolant pump and one cooling fan is provided, multiple coolant pumps and/or multiple cooling fans may be provided.

FIG. 2 illustrates another example fuel cooling system for a diesel internal combustion engine system. The fuel cooling system may include a set of engine cylinders 200, a fuel storage tank 202 for storing fuel, a common rail fuel injection system 206, a fuel recycling circuit 208, temperature sensors 210, a fuel to coolant heat exchange system 212, an air to coolant heat exchange system 214, an engine control unit control unit 216, various sensors 220, and various actuators 222.

The fuel storage tank 202 has a first opening which provides a passage for fuel to flow into the fuel distribution circuit 204. It has a second opening which provides a passage for fuel to return from the fuel distribution circuit 204 under certain conditions.

The fuel distribution circuit 204 includes a chassis fuel pump/filter 204a for pumping fuel out of the fuel storage tank 202 and for pressurizing the fuel; a pressure regulator 204b for regulating the pressure of the pressurized fuel; a primary engine filter 204c for filtering the fuel prior to the fuel entering the common rail fuel injection system 206. It may also be possible in other examples for the fuel distribution circuit 204 to include various other pumps, filters, regulators, bypasses, valves, meters, sensors, controls, actuators etc.

The common rail fuel injection system 206 is coupled on one end to the fuel distribution circuit 204 and on a second end to the engine cylinders 200 and on a third end to the fuel recycling circuit 208. It is possible that the common rail fuel injection system 206 may include additional pressure and/or temperature sensors for sensing fuel pressure and temperature, and it may include additional pressure regulators for controlling the fuel pressure, and may include mechanisms for controlling fuel injection into the engine cylinders.

The fuel recycling circuit 208 is coupled on both ends to the common rail fuel injection system 206 and includes a recirculation filter 208a. On one end, the fuel recycling circuit 208 receives the un-injected fuel from the common rail fuel injection system 206; and on the other end, the fuel recycling circuit 208 recycles fuel back to the common rail fuel injection system 206.

The temperature sensors 210 are positioned in the path of the fuel recycling circuit 208 and in the fuel storage tank.

The fuel to coolant heat exchange system 212 is positioned in the path of the fuel recycling circuit 208 for cooling the un-injected fuel and it is coupled to and cooled by the air to coolant heat exchange system 214.

The air to coolant heat exchange system 214 is coupled to the fuel to coolant heat exchange system 212 for cooling the coolant in the fuel to coolant heat exchange system 212. The air to coolant heat exchange system 214 includes an air to coolant heat exchanger 214a, vehicle ram air 214b, and a cooling fan 214c. The air to coolant heat exchanger 214a serves to exchange heat between air and the coolant. Airflow (as indicated by the dotted lines) may be used to cool the coolant. Airflow 214d may be created by the vehicle ram air 214b when vehicle is moving and/or airflow 214e may be created by a cooling fan 214c when the cooling fan 214c is turned on.

The engine control unit 216 is coupled to the temperature sensors 210, the fuel to coolant heat exchange system 212, the air to coolant heat exchange system 214, and to various other sensors 220 and controls 222 (Not all shown).

The fuel in the storage tank 202 flows into the fuel distribution circuit 204, then into the common rail fuel injection system 206, and finally into the engine cylinders 200 to be injected. In addition, a passage is provided for fuel in the fuel distribution circuit 208 to flow back to the fuel storage tank 202. For example, when the engine is idling or is operating at a low speed so that the fuel delivered to the fuel distribution circuit 204 is excessive to engine requirements, the fuel is re-circulated back to the fuel storage tank 202 from the fuel distribution circuit 204 through a bypass, for example, a pressure regulator 204b (will be further described below) and/or a chassis fuel pump/filter 204a (will be further described below). The un-injected fuel of the common rail fuel injection system 206 is recycled back to the common rail fuel injection system 206 through the fuel recycling circuit 208, without first passing through the fuel storage tank 202. Although un-injected fuel does not flow from the common rail fuel injection system 206 back to the fuel storage tank 202, this may be possible in other embodiments, as illustrated in FIG. 1.

The various embodiments of the fuel cooling system as described in FIG. 1 and their advantages as discussed above in relation to FIG. 1 also apply here to FIG. 2.

Various modifications or adjustments may be made to the above example systems. For example, the fuel storage tank may have opening for receiving un-injected fuel from the common rail fuel injection system, and/or it may have an opening for receiving excess fuel back from the fuel distribution circuit. The fuel distribution circuit may include one or more temperature sensors, pressure sensors, and various other pumps, filters, bypasses, valves, meters, sensors, controls, actuators, etc. The fuel distribution circuit may include one or multiple lines. Further, the common rail fuel injection system may include one or more temperature sensors, pressure sensors, pressure regulators and various other pumps, filters, bypasses, valves, meters, sensors, controls, actuators, etc. Regarding the fuel recycling circuit, it may recycle the fuel back to the fuel storage tank and/or directly back to the common rail fuel injection system. The fuel recycling circuit may be coupled to one or more fuel to coolant heat exchange systems. The fuel recycling circuit may also contain one or more filters, pumps. The fuel recycling circuit may include one or multiple lines.

In one example, the cooling fan may be also be coupled to the engine radiator and used to circulate air through the radiator to cool engine coolant and/or the engine. Alternatively, the cooling fan may be a separate fan from the engine cooling fan and may be used to cool the coolant in the fuel to coolant heat exchange system without also cooling the engine or radiator/engine coolant. One or more fuel to coolant heat exchange systems may be provided. The fuel to coolant heat exchange system may be positioned in the fuel recycling circuit, and/or in the fuel distribution circuit, and/or in other locations along the fuel flow route. In addition, one or multiple fuel to coolant heat exchange systems may be provided. It may also be possible that one or multiple air to coolant heat exchange systems are coupled to a fuel to coolant heat exchange system.

The fuel cooling system may include no pressure sensor, one pressure sensor, or multiple pressure sensors. The pressure sensors may be located in various locations, such as in a common rail of the common rail fuel injection system, in the fuel tank, in a fuel injector, etc. The fuel cooling system may include one or more temperature sensors. The temperature sensors may be located at various locations for sensing temperature, such as in the fuel storage tank, in the fuel distribution circuit, in the common rail fuel injection system, in the fuel recycling circuit, etc.

The control unit may be an engine control unit or may be a unit separate from the engine control unit. It may be configured to send and receive information from various sensors, such as temperature sensors and pressure sensors. It may also be coupled to and control operation of various pumps, such as coolant pump, and various fans, such as engine cooling fan. It may be used to receive information from various other sensors, pumps, actuators and valves etc.

The specific routines described below in the flowcharts may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various acts or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. Although not explicitly illustrated, the illustrated acts or functions may be repeatedly performed depending on the particular strategy being used, during engine operation. Further, these figures may graphically represent code to be programmed into the computer readable storage medium in a controller or control system.

FIGS. 3-8 show high-level flowcharts of example routines for controlling fuel temperature that may be implemented in a vehicle control system, such as an engine control unit (ECU), or in a fuel cooling system, such as illustrated in FIGS. 1-2.

FIG. 3 shows a high-level flowchart of an example routine 300 for selection of a temperature sensor degradation strategy or a normal control strategy for fuel temperature control. Specifically, the routine illustrates selection of the strategy for controlling the fuel temperature in a fuel cooling system. First, the engine control unit (ECU) runs the basic input/output system (BIOS) and determines whether there is any indication of temperature sensor degradation, such as but not limited to short circuit to ground, short circuit to plus, or open loop during various vehicle operating conditions, such as key-on-engine-on (KOEO), key-on-engine-running (KOER), or continued engine operation (CONT); or whether there is any engine torque truncation performed due to fuel temperature too HIGH in 308. If the ECU determines there is temperature sensor degradation, or engine torque truncation has occurred due to excessive fuel temperature, the ECU turns on a Diagnostic Test Code (DTC) in 310. On the other hand, if the ECU does not sense any indication of temperature sensor degradation or engine truncation, then the ECU performs no additional action and a normal control strategy for controlling the fuel temperature is continued in 312. After the ECU turns on the Diagnostic Test Code (DTC) in 310, the ECU determines whether there is temperature sensor degradation in 314. If ECU determines that there is temperature sensor degradation, the ECU overrides the normal control strategy for fuel temperature control and runs the temperature degradation strategy (See FIGS. 6-7) for fuel temperature control in 316. On the other hand, if ECU determines that there is no temperature sensor degradation, the ECU performs no additional action and the normal control strategy (See FIGS. 4-5) for fuel temperature control is continued in 318.

FIG. 4 shows a high-level flowchart of an example routine for a normal coolant pump control strategy. First, the engine control unit determines whether the fuel temperature TFU is greater than a calibratable threshold A (e.g., around 50.degree. C.) in 400. If the engine control unit determines that TFU is greater than the threshold A, then the engine control unit turns on coolant pump in 410. On the other hand, if the engine control unit determines that TFU is not greater than the threshold A, then the engine control unit performs no additional action in 412 (or decreases the engine speed or torque).

FIG. 5 shows a high-level flowchart of an example routine for running a normal engine cooling fan control strategy. First, the engine control unit determines whether the fuel temperature TFU is both greater than a calibratable threshold B (e.g., around 70.degree. C.) and the vehicle speed (VS) is less than a calibratable threshold C in 500. If the engine control unit determines that both TFU is greater than the threshold B and VS is less than the threshold C, then the engine control unit controls the engine cooling fan based on TFU. For example, it may turn on or increase fan speed when TFU is greater than desired, and may turn off or decrease fan speed when TFU is less than desired. On the other hand, if the engine control unit determines that it is not true that both TFU is greater than the threshold B and VS is less than the threshold C, either because TFU is not greater than threshold B or because VS is not less than threshold C, then the engine control unit requests a minimum calibratable fan speed. For example, the minimum fan speed may be a calibratable minimum fan speed based on engine speed, FIG. 6 is a high-level flowchart showing an example routine for running a temperature sensor degradation strategy for controlling the coolant pump. Specifically, the ECU determines if both the fuel temperature sensor has degraded (e.g., through a routine as illustrated in FIG. 3) and the intake air temperature is greater than a calibratable threshold D in 600. If both the fuel temperature sensor has failed and the intake air temperature is greater than a calibratable threshold D, then the ECU turns on the coolant pump (or increases speed or torque of the coolant pump) in 610. Otherwise, if it is not true that both the fuel temperature sensor has degraded and the intake air temperature is greater than a calibratable threshold D, either because there is no temperature sensor degradation or because the intake air temperature is not greater than threshold D, then the ECU turns off the coolant pump (or decreases speed or torque of the coolant pump in 612

FIG. 7 is a high-level flowchart showing an example routine for a temperature sensor degradation strategy for controlling the engine cooling fan. Specifically, the ECU determines if both the fuel temperature sensor has degraded (e.g., through a routine as illustrated in FIG. 3) and the vehicle speed (VS) is less than a calibratable threshold E in 700. If both the fuel temperature sensor has failed and the VS is less than a calibratable threshold E, then the ECU controls the engine cooling fan based on engine speed by looking up a calibratable fan speed to engine speed table in 712. Otherwise, when either there is no fuel temperature sensor degradation or the VS is not less than the calibratable threshold E, then the ECU performs no action in 714.

If the fuel temperature sensor has degraded, the strategy infers the fuel temperature based on the inlet air temperature to determine whether to turn ON/OFF the coolant pump. The viscous fan provides additional cooling if the fuel temperature continues to rise with the coolant pump ON.

FIG. 8 is a flowchart showing an example routine for performing a torque truncation operation. Specifically, the engine control unit (ECU) determines whether the fuel temperature TFU is greater than a calibratable temperature threshold F (e.g., around 70.degree. C.) in 800. If TFU is greater than threshold F, then the ECU performs an engine torque truncation, for example through a fuel temperature sensor logic in 810. Otherwise, if TFU is not greater than threshold F, then the ECU performs no additional action in 812. If ECU performs an engine torque truncation in 810, the ECU then runs the diagnostic test code for the temperature sensors in 814. The engine torque may be truncated in a plurality of ways, such as reducing an amount of fuel injection, changing (e.g., delaying) injection timing, increasing throttling, and various others.

By providing a mechanism to independently control the coolant pump and the engine cooling fan, the fuel cooling system may have more latitude to more precisely control fuel temperature for particular operating conditions. For example, when the fuel temperature is above a certain calibratable threshold A, for example above around 50.degree. C., the engine control unit adjusts the coolant pump. When both the fuel temperature is above another calibratable threshold B, for example above around 70.degree. C., and the vehicle speed is less than a calibratable threshold C, the engine control unit controls the engine cooling fan based on the fuel temperature. Otherwise, the engine control unit controls the engine cooling fan to a min calibratable speed. Further, by providing a mechanism for performing engine torque truncation when the fuel temperature is excessively high, for example at above 105.degree. C., the fuel cooling system may be able to further control the returning fuel temperature. Finally, by providing a fuel temperature sensor degradation strategy in addition to a normal strategy, the fuel cooling system may still provide necessary cooling when the fuel temperature sensor degrades. And, by providing a diagnostic code for the fuel temperature sensor, the fuel cooling system may be able to timely detect any degradation of the fuel temperature sensor and run the fuel temperature sensor degradation strategy

The following claims particularly point out certain combinations and subcombinations regarded as novel and nonobvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.

[Turtle_n_Peeps]

So if lubricity IS the issue, what kind of damage could be done to the HPFP by dry cranking the engine, with no fuel in the HPFP to lubricate it? I know that it isn't good on any diesel to be dry cranked because the diesel is used to lubricate more than just the fuel pump, such as the cylinder walls. So do you think dry cranking could result in the destruction of the cp4.2?

When a diesel engine runs out of fuel the pump is not dry. It will loose pressure and it will die but the pump will be wet.

As far as fuel lubbing the cylinders. That don't wash because modern engines have a fuel cut-off when coasting down hill. If that happened you would hurt your engine every time you coasted.

[NewsW]

W4RLR wrote:
Too bad I have one of those 6.0 engines that are ticking time bombs... climbing to 130,000 miles and zero issues,

Yours is barely broken in by my standards.

Try twice the mileage.

[NewsW]

2003silverado wrote:

So if lubricity IS the issue, what kind of damage could be done to the HPFP by dry cranking the engine, with no fuel in the HPFP to lubricate it? I know that it isn't good on any diesel to be dry cranked because the diesel is used to lubricate more than just the fuel pump, such as the cylinder walls. So do you think dry cranking could result in the destruction of the cp4.2?

For quite some time now, Diesel fuel pumps have been rigged up so it rarely runs dry (except for the brief time when filters are changed).

Think in the Ford, there is a shut off if the fuel level is too low, as measured by the fuel level sender in the tank.

Another shutoff is the pressure sensor on the pump itself.

[2003silverado]

I've been following this thread lately and its been an interesting read. I thought about something else that may pose an issue after reading this talk about lubricity possibly playing a key role in the demise of a number of HPFPs.

I was talking to my very good friend the other night that drives a 2011 superduty with the 6.7 diesel. First off I will say he loves his truck and hasn't heard anything about the HPFP issues. This is what got me thinking...He owns a large rental company in mid Michigan and they do events nation-wide. Last week they did a job in Florida, and he had 6 semis drive down and along with his Superduty pulling a gooseneck. After 15 hours of driving, he let one of his employees take over driving the truck while he took a nap. The new driver didn't pay very good attention to fuel levels and when Tom woke up he asked about the fuel situation and the DIC said 1 mile to empty! It was 3 in the morning and every exit they got off at the stations that had diesel were closed. They ened up running the truck out of diesel. They had one of their other trucks find a truck stop and buy some gas cans and they carted diesel back to his truck. (Now I don't know how to prime the system on the 6.7 or if they did it properly) but he said that they went through 20-25 seconds of cranking until it stated back up.

So if lubricity IS the issue, what kind of damage could be done to the HPFP by dry cranking the engine, with no fuel in the HPFP to lubricate it? I know that it isn't good on any diesel to be dry cranked because the diesel is used to lubricate more than just the fuel pump, such as the cylinder walls. So do you think dry cranking could result in the destruction of the cp4.2?

[W4RLR]

1jeep wrote:
Too bad i traded in one of those horrible 6.4 diesels that had 100k miles with zero issues for this horrible 6.7!

Quick someone come take this thing off my hands before the fuel pump stops working!!

Too bad I have one of those 6.0 engines that are ticking time bombs... climbing to 130,000 miles and zero issues, other than the fact that she hates being awakened on a cold morning. For that matter, so does my wife but I have no plans on trading her in, either.

[FishOnOne]

NewsW wrote:

hawkeye-08 wrote:
I think Delphi has the answer to this Bosch pump problem. I had read that they patented the fix to the CP4 pumps and they also came out with a new pump that incorporated their patents. Bosch is too stubborn to pay Delphi the license fees for the better pump...

New VW with Delphi HPFS pump

... and of course the poster over on FTE that posted this..

http://www-odi.nhtsa.dot.gov/acms/do...003-45604P.pdf

The Bosch CP 4.X series of pumps are a family of pumps, with the same inherent design flaw, such that a law firm in Texas has a class action lawsuit against VW/ Bosch for it, you can find it at the end of the NHSTA pdf above on pages 316 to 333.

There is no factual evidence documenting the "design flaw" that have yet been made public.

I have as much faith in a law firm making such allegations as I have with FTE.

If there is a Delphi patent, give me the number or publish it --- lets examine the patent to see if it has any validity to the issues at hand.

Wow... Asking for legitimate data to back up such statement. Amazing!

[NewsW]

hawkeye-08 wrote:
I think Delphi has the answer to this Bosch pump problem. I had read that they patented the fix to the CP4 pumps and they also came out with a new pump that incorporated their patents. Bosch is too stubborn to pay Delphi the license fees for the better pump...

New VW with Delphi HPFS pump

... and of course the poster over on FTE that posted this..

http://www-odi.nhtsa.dot.gov/acms/do...003-45604P.pdf

The Bosch CP 4.X series of pumps are a family of pumps, with the same inherent design flaw, such that a law firm in Texas has a class action lawsuit against VW/ Bosch for it, you can find it at the end of the NHSTA pdf above on pages 316 to 333.

There is no factual evidence documenting the "design flaw" that have yet been made public.

I have as much faith in a law firm making such allegations as I have with FTE.



If there is a Delphi patent, give me the number or publish it --- lets examine the patent to see if it has any relevance to the issues at hand.


Delphi made a very small sale to VW, a bottom of the line product.

Pretty far from the bread and butter CP series of pumps.

Did you notice Delphi did not make a sale to GM?

To me the competition to watch is Denso.