Method and system for engine control

Patent metadata

Field	Value
Publication number	US-9897020-B2
Application number	US-201615181198-A
Country	US
Kind code	B2
Filing date	Jun 13, 2016
Priority date	Jun 13, 2016
Publication date	Feb 20, 2018
Grant date	Feb 20, 2018

Abstract

Methods and systems are provided for reducing a spark plug soot load and a combustion chamber soot load by controlling spark plug timing while injecting water or washer fluid. In one example, water or washer fluid is injected during a torque reduction while advancing spark timing so as to provide at least a portion of the torque reduction while opportunistically cleaning soot from the spark plug and combustion chamber. By reducing spark plug soot load, misfire occurrence is reduced, while pre-ignition occurrence is reduced by decarbonizing the combustion chamber.

First claim

The invention claimed is:

1. A method for an engine, comprising:
in response to a torque reduction request received while a predicted engine soot load is higher than a threshold load,
injecting a fluid into an intake manifold or a cylinder, and;
adjusting spark ignition timing based on the fluid injection.

2. The method of claim 1 , wherein the adjusting spark ignition timing is based on the fluid injection includes adjusting based on one or more of an amount of fluid injected, a rate of fluid injection, an alcohol content of the injected fluid, an amount of heat transfer desired at the spark plug, a total engine torque output desired.

3. The method of claim 2 , wherein the amount of fluid injected and the rate of fluid injection are based on each of the predicted engine soot load and the torque reduction request, the rate of fluid injection and the amount of fluid injected increased to a limit as the predicted engine soot load increases, and as more torque reduction is requested.

4. The method of claim 1 , wherein the predicted engine soot load includes one of a predicted spark plug soot load and a predicted combustion chamber soot load.

5. The method of claim 4 , wherein the predicted spark plug soot load is predicted based on one or more of a modeled spark plug tip temperature, an engine misfire count, an indication of spark plug fouling, and a measured ion leakage current, and wherein the predicted combustion chamber soot load is based on one or more of an engine pre-ignition count, an engine knock count, and an alcohol content of the injected fluid.

6. The method of claim 1 , wherein the fluid is one of water and washer fluid, and wherein the washer fluid includes methanol.

7. The method of claim 2 , further comprising, increasing engine idling speed while injecting the fluid, the increasing based on one or more of the amount of fluid injected, the rate of fluid injection, and the alcohol content of the injected fluid.

8. The method of claim 1 , wherein the torque reduction request includes one of a transmission shift, and traction control.

9. The method of claim 1 , wherein adjusting spark timing includes maintaining spark timing.

10. The method of claim 1 , wherein adjusting spark timing include advancing spark timing of MBT for torque reduction and heating a spark plug, the adjusting including retarding spark timing from MBT for torque reduction only.

11. The method of claim 10 , further comprising, in response to a torque reduction request received while the predicted engine soot load is lower than the threshold load, retarding spark timing.

12. A method for an engine, comprising:
in response to a first torque reduction request from an initial torque level, retarding spark timing; and
in response to a second torque reduction request from the initial torque level, injecting a water-based fluid into the engine while maintaining spark ignition timing, wherein an amount of torque reduction requested during the first torque reduction request and the second torque reduction request is same.

13. The method of claim 12 , wherein during the first torque reduction request, a spark plug soot load is lower, and during the second torque reduction request, the spark plug soot load is higher, and wherein during both the first and second torque reduction request, the spark plug soot load is predicted based on each of a modeled spark plug tip temperature, an engine misfire count, an engine pre-ignition count, an indication of spark plug fouling, and a measured ion leakage current.

14. The method of claim 12 , wherein the water-based fluid includes one of water and washer fluid, wherein the washer fluid includes methanol, and wherein injecting the fluid includes injecting into an intake passage or injecting directly into a cylinder.

15. The method of claim 13 , wherein during the first torque reduction request, a degree of spark timing retard is based on an amount of torque reduction requested, the degree of spark timing retard increased as the amount of torque reduction increases, and wherein during the second torque reduction request, a rate of fluid injection is based on the amount of torque reduction requested and further based on the soot load, the rate of fluid injection increased as the amount of torque reduction requested increases and as the soot load exceeds a threshold load.

16. The method of claim 15 , wherein the threshold load is based on a pre-ignition count of the engine, the threshold load decreased as the pre-ignition count increases.

17. The method of claim 12 , further comprising, after the first torque reduction request, operating the engine at a first idling speed, and after the second torque reduction request, operating the engine at a second idling speed, the second idling speed higher than the first idling speed.

18. An engine system, comprising:
an engine including a cylinder;
a first injector for delivering a first fluid into the cylinder;
a second injector for delivering a second fluid upstream of the cylinder;
a transmission including a plurality of gears;
a spark plug; and
a controller with computer-readable instructions stored on non-transitory memory for:
modeling a soot load of the spark plug based on engine operating conditions; and
in response to the soot load being higher than a threshold load,
injecting the second fluid while advancing spark ignition timing by a smaller amount if a torque reduction event is predicted; and
advancing spark ignition timing by a larger amount if the torque reduction event is not predicted.

19. The system of claim 18 , wherein the controller includes further instructions for:
adjusting injection of the first fluid responsive to the injecting of the second fluid, wherein the injection of the first fluid is decreased as the injecting of the second fluid increases, the first fluid including gasoline, the second fluid including methanol, and wherein the torque reduction event includes a transmission gear shift.

20. The system of claim 18 , wherein the controller includes further instructions for:
after the torque reduction event, increasing engine idling speed by a smaller amount while injecting the second fluid when the torque reduction event is predicted; and
increasing engine idling speed spark by a larger amount while advancing spark ignition timing when the torque reduction event is not predicted.

Assignees

• Ford Global Tech Llc

Inventors

• Glugla Chris Paul
• Czekala Michael Damian
• Huberts Garlan J
• Surnilla Gopichandra

Classifications

• F02P5/15

  Digital data processing · CPC title

• F02D41/16

  for idling · CPC title

• F02P5/045

  combined with electronic control of other engine functions, e.g. fuel injection (in general F02D37/02) · CPC title

• F02D41/0025 Primary

  Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures · CPC title

• F02P17/12

  Testing characteristics of the spark, ignition voltage or current (testing of sparking plugs H01T13/60) · CPC title