Engine variable oil pump diagnostic method

Patent metadata

Field	Value
Publication number	US-11022010-B2
Application number	US-201715853107-A
Country	US
Kind code	B2
Filing date	Dec 22, 2017
Priority date	Dec 22, 2017
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

Methods and systems are provided for diagnosing the functioning of a variable displacement oil pump. In one example, a method may include commanding a change in displacement of the variable displacement oil pump during a vehicle keyed-off condition and diagnosing a degradation of the oil pump based on a corresponding change in an estimated crankcase pressure.

First claim

The invention claimed is:

1. A method comprising:
indicating degradation of a variable displacement oil pump (VDOP) based on a change in an estimated crankcase pressure, upon a commanded change in VDOP displacement,
wherein the commanded change in VDOP displacement is from a high displacement mode with a solenoid de-energized to a low displacement mode with the solenoid energized, the high displacement mode being a default mode during a vehicle off condition, and wherein the indicating degradation of the VDOP includes estimating a first crankcase pressure during VDOP operation in the high displacement mode, and indicating that the VDOP is stuck in the low displacement mode responsive to the first crankcase pressure being lower than a first baseline pressure, and
wherein the commanded change in VDOP displacement includes commanding the change while cranking an engine, unfueled, via an electric machine.

2. The method of claim 1 , further comprising, upon the indicating the degradation of the VDOP, during subsequent vehicle on condition, adjusting an engine idling speed responsive to the indication of degradation of the VDOP.

3. The method of claim 2 , wherein the commanding the change in VDOP displacement is during the vehicle off condition when engine temperature is substantially equal to ambient temperature.

4. The method of claim 2 , wherein indicating degradation of the VDOP includes estimating a second crankcase pressure during VDOP operation in the low displacement mode, and indicating that the VDOP is stuck in the high displacement mode responsive to the second crankcase pressure being lower than a second baseline pressure, the second baseline pressure lower than the first baseline pressure.

5. The method of claim 4 , wherein indicating degradation of the VDOP further includes indicating that the VDOP is stuck in the high displacement mode responsive to a difference between the first crankcase pressure and the second crankcase pressure being lower than a threshold difference.

6. The method of claim 4 , wherein each of the first crankcase pressure and the second crankcase pressure are estimated via a crankcase pressure sensor housed in a crankcase ventilation tube coupling a crankcase to an engine intake manifold.

7. The method of claim 6 , further comprising establishing the first baseline pressure via the crankcase pressure sensor upon installation of the VDOP by operating the VDOP in the high displacement mode while cranking the engine unfueled at the idling speed; and establishing the second baseline pressure via the crankcase pressure sensor upon installation of the VDOP by operating the VDOP in the low displacement mode while cranking the engine unfueled at the idling speed.

8. The method of claim 2 , wherein adjusting the engine idling speed includes increasing the engine idling speed responsive to the VDOP being stuck in the low displacement mode.

9. A method for an engine, comprising:
during a vehicle off condition,
rotating the engine via an electric motor;
estimating a first crankcase pressure while operating an oil pump in a high displacement mode; and
indicating that the oil pump is stuck in a low displacement mode based on the first crankcase pressure being lower than a first baseline pressure; and

during a subsequent vehicle on condition, increasing an engine idle speed responsive to the indicating, wherein the first baseline pressure is established within a threshold duration of installation of the oil pump.

10. The method of claim 9 , wherein the oil pump is a variable displacement oil pump and wherein operating in the high displacement mode includes de-energizing a solenoid.

11. The method of claim 10 , further comprising transitioning the pump from the high displacement mode to the low displacement mode by energizing the solenoid.

12. The method of claim 11 , further comprising, after the transitioning, estimating a second crankcase pressure and indicating that the oil pump is stuck in the high displacement mode responsive to the second crankcase pressure being higher than a second baseline pressure, the second baseline pressure lower than the first baseline pressure.

13. The method of claim 12 , wherein each of the first crankcase pressure, the second crankcase pressure, the first baseline pressure, and the second baseline pressure are estimated via a crankcase pressure sensor while the engine is rotated unfueled via the electric motor during the vehicle off condition.

14. The method of claim 12 , further comprising establishing the second baseline pressure within the threshold duration of the installation of the oil pump.

15. A hybrid vehicle system, comprising:
an engine;
an electric machine coupled to a battery capable of rotating the engine;
a crankcase including a variable displacement oil pump mechanically coupled to the engine;
a solenoid configured to adjust a displacement of the oil pump;
a crankcase vent tube mechanically connected to an intake passage upstream of a compressor, the tube also mechanically connected to the crankcase;
a crankcase pressure sensor coupled to the crankcase vent tube; and
a controller with computer readable instructions stored on non-transitory memory for:
during an engine-off condition,
cranking the engine, unfueled, via the electric machine,
commanding a change in displacement of the variable displacement oil pump via the solenoid;
sensing crankcase pressure via the crankcase pressure sensor before and after the commanded change in displacement;
indicating degradation of the oil pump based on the sensed crankcase pressure relative to a baseline pressure, the baseline pressure including a first baseline pressure and a second baseline pressure; and
establishing the first baseline pressure by rotating the engine via the electric machine when the oil pump is first installed and operated in a high displacement mode, and establishing the second baseline pressure by rotating the engine via the electric machine when the oil pump is first installed and operated in a low displacement mode.

16. The system of claim 15 , wherein the commanded change in displacement is from the high displacement mode to the low displacement mode, and wherein indicating degradation of the oil pump includes:
indicating that the oil pump is stuck in the low displacement mode with the solenoid de-energized responsive to the sensed crankcase pressure before the commanded change in displacement being lower than the first baseline pressure; and
indicating that the oil pump is stuck in the high displacement mode with the solenoid energized responsive to the sensed crankcase pressure after the commanded change in displacement being higher than the second baseline pressure.

17. The method of claim 1 , further comprising, during engine operation, varying oil flow rate output from the VDOP based on a sensed oil pressure from an oil pressure sensor coupled to the VDOP.

Assignees

• Ford Global Tech Llc

Inventors

• Dudar Aed M

Classifications

• F02D41/042

  for stopping the engine · CPC title

• F01M2013/0083

  Crankcase pressure · CPC title

• F01M2001/0246

  Adjustable pumps · CPC title

• F01M2001/0215

  Electrical pumps · CPC title

• F01M2001/0269

  driven by the crankshaft · CPC title