Methods for detecting high pressure pump bore wear

Patent metadata

Field	Value
Publication number	US-9506417-B2
Application number	US-201414255824-A
Country	US
Kind code	B2
Filing date	Apr 17, 2014
Priority date	Apr 17, 2014
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

Methods are provided for detecting high pressure pump bore wear, wherein wear between a piston and bore of a pump may cause an excessive amount of fuel to leak out of a compression chamber of the pump. A reliable method is needed that involves a pump performance model that incorporates a number of physical effects and is verified by real high pressure pump test data. A method is proposed that involves comparing a target pump rate based on the pump performance model to a real fuel injection rate in order to determine if an abnormal amount of fuel may be leaking from the high pressure pump.

First claim

The invention claimed is:

1. A method, comprising:
while an engine is at an idling speed:
increasing pressure in a direct injection fuel rail of the engine to a threshold fuel rail pressure;
computing a target pump rate of a high pressure fuel pump based on a pump performance model;
computing a fuel injection rate;
comparing the target pump rate and the fuel injection rate; and
issuing a piston-bore interface leak result based on the comparison.

2. The method of claim 1 , wherein the piston-bore interface leak result is abnormal if the comparison determines that the target pump rate is higher than the fuel injection rate by more than a margin.

3. The method of claim 2 , wherein the margin includes a value of uncertainty.

4. The method of claim 1 , wherein the piston-bore interface leak result is normal if the comparison determines that the target pump rate is equal to or lower than the fuel injection rate plus a margin.

5. The method of claim 4 , wherein the margin includes a value of uncertainty.

6. The method of claim 1 , wherein the pump performance model is calculated based on fuel loss due to bulk modulus of the fuel and a dead volume of a compression chamber of the high pressure fuel pump, normal leak through the piston-bore interface, and a miscellaneous cause.

7. The method of claim 1 , wherein the pump performance model is calculated by a controller with computer readable instructions stored in non-transitory memory, the controller located on-board a vehicle with the engine.

8. The method of claim 1 , wherein the fuel injection rate is computed based on measurements from one or more sensors of the engine.

9. A method, comprising:
upon completion of an initiation condition and while an engine is at an idling speed:
increasing pressure in a direct injection fuel rail of the engine to a threshold fuel rail pressure;
computing a target pump rate of a high pressure fuel pump based on a pump performance model;
computing a fuel injection rate;
comparing the target pump rate and the fuel injection rate; and
diagnosing a piston-bore interface as abnormally leaking if the target pump rate is higher than the fuel injection rate by more than a margin.

10. The method of claim 9 , wherein the margin includes a value of uncertainty.

11. The method of claim 9 , wherein the pump performance model is calculated based on fuel loss due to bulk modulus of the fuel and a dead volume of a compression chamber of the high pressure fuel pump, normal leak through the piston-bore interface, and a miscellaneous cause.

12. The method of claim 9 , wherein the pump performance model is calculated by a controller with computer readable instructions stored in non-transitory memory, the controller located on-board a vehicle with the engine.

13. The method of claim 9 , wherein the fuel injection rate is computed based on measurements from one or more sensors of the engine.

14. The method of claim 9 , wherein the initiation condition includes a starting command by a person, an automatic starting command by an engine controller, or a starting command issued every time the engine enters the idling condition.

15. A fuel system, comprising:
one or more direct fuel injectors configured to inject fuel into one or more cylinders of an engine;
a fuel rail fluidly coupled to the one or more direct fuel injectors;
a high pressure fuel pump fluidly coupled to the fuel rail; and
a controller with computer readable instructions stored in non-transitory memory for:
while an engine is at an idling speed, increasing pressure in the fuel rail, computing a target pump rate of the high pressure fuel pump based on a pump performance model, computing a fuel injection rate, comparing the target pump rate and the fuel injection rate, and issuing a piston-bore interface leak result based on the comparison.

16. The fuel system of claim 15 , wherein the piston-bore interface leak result is abnormal if the comparison determines that the target pump rate is higher than the fuel injection rate by more than a margin.

17. The fuel system of claim 16 , wherein the margin includes a value of uncertainty.

18. The fuel system of claim 15 , wherein the piston-bore interface leak result is normal if the comparison determines that the target pump rate is lower than the fuel injection rate plus a margin.

19. The fuel system of claim 18 , wherein the margin includes a value of uncertainty.

20. The fuel system of claim 18 , wherein an amount of fuel leakage corresponding to the normal piston-bore interface leak result lubricates the high pressure fuel pump.

Assignees

• Ford Global Tech Llc

Inventors

• Ulrey Joseph Norman
• Pursifull Ross Dykstra
• Meinhart Mark
• Surnilla Gopichandra

Classifications

• F02M63/029

  per cylinder bank, e.g. storing different fuels or fuels at different pressure levels per cylinder bank · CPC title

• F02M65/002

  Measuring fuel delivery of multi-cylinder injection pumps · CPC title

• F02D2200/0614

  Actual fuel mass or fuel injection amount · CPC title

• F02D2041/225

  Leakage detection · CPC title

• F02D41/221

  relating to the failure of actuators or electrically driven elements · CPC title