LIFT PUMP CONTROL FOR A TWO PUMP DIRECT INJECTION FUEL SYSTEM

• US 20090114191A1
• Filed: 11/02/2007
• Published: 05/07/2009
• Est. Priority Date: 11/02/2007
• 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 8,061,329 B2
• Time in Patent Office: Days
• US Class Current: 123/447
• CPC Class Codes: F02D 2041/2027 Control of the current by pulse width modulation or duty cycle control
• CPC Class Codes: F02D 2200/0604 Estimation of fuel pressure
• CPC Class Codes: F02D 2250/31 Control of the fuel pressure
• CPC Class Codes: F02D 41/2496 the memory being part of a closed loop
• CPC Class Codes: F02D 41/3854 with elements in the low pressure part, e.g. low pressure pump
• CPC Class Codes: F02D 41/406 Electrically controlling a diesel injection pump F02D41/401 takes precedence
• CPC Class Codes: F02M 37/0058 Returnless fuel systems, i.e. the fuel return lines are not entering the fuel tank
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An economical method for controlling a lift pump operating as part of a direct injection fuel system is described. According to the method, at least two distinct operating modes are provided.

Claims

1. A method to operate a lower pressure pump operating as part of a direct injection fuel system, the method comprising:

operating a lower pressure pump in a first mode during a first operating condition of an internal combustion engine, said lower pressure pump supplying fuel to a higher pressure pump that supplies fuel to fuel injectors that directly inject fuel to a cylinder, said first operating mode comprising adjusting energy supplied to said lower pressure pump as output from a sensor located downstream of said higher pressure pump varies while said higher pressure pump is substantially deactivated; and

operating said lower pressure pump in a second mode during a second operating condition of said internal combustion engine, said second operating mode comprising varying energy supplied to said lower pressure pump as operating conditions of said internal combustion engine vary while said higher pressure pump is activated.

2. The method of claim 1 wherein said energy is delivered as a voltage or current.

3. The method of claim 1 wherein said sensor is a pressure sensor.

4. The method of claim 2 further comprising varying said current or voltage as operating conditions of said internal combustion engine vary.

5. The method of claim 1 wherein said higher pressure pump is substantially deactivated during said first mode.

6. The method of claim 1 wherein operation in said first and second modes is determined from engine operating conditions.

7. The method of claim 1 wherein said higher pressure pump is driven by said internal combustion engine.

8. The method of claim 1 wherein said engine operating conditions are comprised of at least one of a driver torque request, engine speed, engine load, ambient temperature, or engine temperature.

9. The method of claim 1 wherein a fuel injection mode is changed at substantially the same time that the mode of said lower pressure pump is changed.

10. The method of claim 5 wherein said higher pressure pump is deactivated in conjunction with deceleration fuel cut-out.

11. A method to operate a lift pump operating as part of a direct injection fuel system, the method comprising:

operating a lift pump in a first mode during a first operating condition of an internal combustion engine, said lift pump supplying fuel to an injection pump that supplies fuel to fuel injectors that directly inject fuel to a cylinder, said first operating mode comprising adjusting energy supplied to said lift pump as output from a sensor located downstream of said injection pump varies while said injector pump is deactivated;

storing lift pump variable that corresponds to a pressure observed at said sensor; and

operating said lift pump in a second mode wherein said lift pump variable is used to regulate the pressure at the outlet of said lift pump.

12. The method of claim 11 further comprising varying said energy in said first mode when operating conditions of said internal combustion engine vary.

13. The method of claim 11 further comprising operating said injection pump to increase the pressure of fuel delivered from said lift pump.

14. The method of claim 11 wherein said lift pump variable is an amount of current delivered to said lift pump.

15. The method of claim 11 wherein said lift pump variable is an amount of voltage delivered to said lift pump.

16. The method of claim 11 wherein said lift pump variable is a lift pump temperature.

17. The method of claim 11 wherein said lift pump variable is stored in a function, array, or table that is indexed by lift pump operating conditions.

18. A computer readable storage medium having stored data representing instructions executable by a computer to control a lift pump located upstream of an injection pump that supplies fuel to an injector that delivers fuel into a of an internal combustion engine of a vehicle, said storage medium comprising:

instructions for adjusting energy supplied to said lift pump as the amount of fuel consumed by said internal combustion engine varies; and

instructions for further adjusting energy supplied to said lift pump as operating conditions of said lift pump vary.

19. The computer readable storage medium of claim 18 wherein said operating conditions include an actual or inferred temperature of said lift pump.

20. The computer readable storage medium of claim 18 wherein said storage medium comprises further instructions for deactivating said injection pump while said energy is being adjusted as operating conditions of said lift pump vary.