LIFT PUMP SYSTEM FOR A DIRECT INJECTION FUEL SYSTEM

• US 20090188472A1
• Filed: 01/29/2008
• Published: 07/30/2009
• Est. Priority Date: 01/29/2008
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Ulrey, Joseph Norman, Pursifull, Ross Dykstra
• Granted Patent: US 7,640,916 B2
• Time in Patent Office: Days
• US Class Current: 123/495
• CPC Class Codes: F02B 2075/125 Direct injection in the combustion chamber for spark ignition engines, i.e. not in pre-combustion chamber
• CPC Class Codes: F02D 13/0253 Fully variable control of valve lift and timing using camless actuation systems such as hydraulic, pneumatic or electromagnetic actuators, e.g. solenoid valves
• CPC Class Codes: F02D 2041/389 for injecting directly into the cylinder
• CPC Class Codes: F02D 33/003 Controlling the feeding of liquid fuel from storage containers to carburettors or fuel-injection apparatus control of electrical fuel pumps F02D41/3082, controlling fuel flow to a common rail F02D41/3845; Failure or leakage prevention; Diagnosis or detection of failure; Arrangement of sensors in the fuel system; Electric wiring; Electrostatic discharge
• CPC Class Codes: F02D 41/3082 Control of electrical fuel pumps
• CPC Class Codes: F02M 37/0058 Returnless fuel systems, i.e. the fuel return lines are not entering the fuel tank
• CPC Class Codes: F02M 37/10 submerged in fuel, e.g. in reservoir
• CPC Class Codes: F02M 55/04 Means for damping vibrations or pressure fluctuations in injection pump inlets or outlets
• CPC Class Codes: F02M 59/102 Mechanical drive, e.g. tappets or cams F02M45/063 takes precedence
• CPC Class Codes: F02M 63/028 Returnless common rail system
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

An economical method for controlling a lift pump operating as part of a direct injection fuel system is described. According to the method, the lift pump is operated at efficient operating conditions and then stopped until additional fuel is requested.

Claims

1. A system for delivering fuel directly to a cylinder of an internal combustion engine, the system comprising:

a fuel lift pump supplying fuel to an injection pump;

an accumulator located between the output of said lift pump and the input of said injection pump; and

a controller that adjusts energy supplied to said lift pump such that a pressure at the inlet of said injection pump is above a first predetermined amount and wherein said controller stops energy supplied to said first fuel pump when said pressure at the inlet of said injection pump is greater than a second predetermined amount.

2. The system of claim 1 wherein said first predetermined amount is related to a fuel vapor pressure.

3. The system of claim 2 wherein said fuel vapor pressure is measured or inferred.

4. The system of claim 1 wherein the speed of said lift pump goes to zero after said controller stops current flow to said first fuel pump.

5. The system of claim 1 wherein said energy is a controlled voltage or current.

6. The system of claim 1 wherein said lift pump is electrically driven and said injection pump is mechanically driven.

7. The system of claim 1 wherein said pressure is determined from a pressure transducer.

8. The system of claim 5 wherein said voltage or current is supplied at a level that operates said fuel pump within 15% of the fuel pump rated operating efficiency for a given pump inlet fuel pressure.

9. The method of claim 6 wherein said injection pump is driven by said internal combustion engine.

10. A system for delivering fuel directly to a cylinder of an internal combustion engine, the system comprising:

a first electrically driven fuel pump supplying fuel to a second mechanically driven fuel pump;

an accumulator located between the output of said first fuel pump and the input of said second mechanically driven fuel pump; and

a controller that supplies current to said first fuel pump to when the efficiency of said second mechanically driven fuel pump is less than a predetermined amount and wherein said controller stops current flow to said first fuel pump when the efficiency of said second mechanically driven fuel pump is greater than a predetermined amount.

11. The system of claim 10 wherein said controller further conditions stopping current flow to said first fuel pump in response to an inferred or measured pressure at the inlet of said second mechanically driven fuel pump.

12. The system of claim 10 wherein the amount of fuel consumed while said first electrically driven fuel pump is deactivated is used to determine the efficiency of said second mechanically driven fuel pump.

13. The system of claim 11 wherein said inferred or measured pressure is greater than the vapor pressure of the fuel supplied to the inlet of said second fuel pump.

14. The system of claim 10 wherein said efficiency of said second mechanically driven fuel pump is determined from the volumetric flow rate of said second mechanically driven fuel pump.

15. The system of claim 10 wherein said controller further conditions stopping current flow to said first fuel pump when fuel fills more than a predetermined volume of an accumulator located downstream of said first fuel pump.

16. A method to deliver fuel to a cylinder of an internal combustion engine, the method comprising:

combusting fuel in at least a cylinder of said internal combustion engine;

operating a electrically driven fuel pump in a first mode to deliver said fuel from a fuel source to an accumulator and a mechanically driven fuel pump while said engine is combusting said fuel, said electrically driven fuel pump being activated in said first mode when fuel pressure at the inlet of said mechanically driven fuel pump is below a predetermined level, said electrically driven fuel pump being deactivated in said first mode when fuel pressure at the inlet of said mechanically driven fuel pump is above a predetermined level;

operating a mechanically driven fuel pump to deliver fuel from said mechanically driven fuel pump to at least a fuel injector; and

injecting fuel from said at least a fuel injector directly into said cylinder of said internal combustion engine.

17. The method of claim 16 wherein fuel pump speed of said electrically driven fuel pump goes to zero after said electrically driven fuel pump is deactivated.

18. The method of claim 16 further comprising a second mode of operating said electrically driven fuel pump wherein said electrically driven fuel pump is operated continuously while the amount of fuel injected to said internal combustion exceeds a predetermined level.

19. The method of claim 16 wherein the average voltage applied to said electrically driven fuel pump is varied as the amount of fuel injected to said internal combustion varies.

20. The method of claim 16 wherein said accumulator is sized to enable said engine to idle for a period exceeding one minute without activating said electrically driven fuel pump.

21. A method to deliver fuel to a cylinder of an internal combustion engine, the method comprising:

combusting fuel in at least a cylinder of said internal combustion engine;

operating a first fuel pump in a first mode when the amount of fuel being delivered to said internal combustion engine is less than a first amount, said first mode comprising delivering said fuel from a fuel source to a second fuel pump during said combustion, said first fuel pump being activated in said first mode when fuel pressure supplied to the inlet of said second fuel pump is below a predetermined level, said first fuel pump being deactivated in said first mode when fuel pressure supplied to the inlet of said second fuel pump is above a predetermined level; and

operating said first fuel pump in a second mode when the amount of fuel being delivered to said internal combustion engine is greater than said first amount, said second mode comprising delivering said fuel from said fuel source to said second fuel pump while there is combustion occurring during a cycle of said at least a cylinder, said first fuel pump being supplied a varying voltage without the speed of said fuel pump going to zero.

22. The method of claim 21 wherein when voltage is applied to said first fuel pump during said first mode, said voltage is substantially constant.

23. The method of claim 21 wherein fuel pump speed goes to zero after said fuel pump is deactivated in said first mode.

24. The method of claim 21 wherein said varying voltage is a pulsewidth modulated voltage.

25. The method of claim 21 further comprising an accumulator positioned between the output of said first fuel pump and the input of said second fuel pump.

26. The method of claim 21 wherein deactivation of said first fuel pump is further determined by a volume of fuel in an accumulator located downstream of said first fuel pump.