Method and system for engine control

Patent metadata

Field	Value
Publication number	US-2016369762-A1
Application number	US-201514742479-A
Country	US
Kind code	A1
Filing date	Jun 17, 2015
Priority date	Jun 17, 2015
Publication date	Dec 22, 2016
Grant date	—

Abstract

Methods and systems are provided for improving engine spark and torque control. In one example, adaptive spark control of an engine may include a modifier that adjusts the inferred fuel octane estimate and a spark adaptation based on ambient humidity. The method allows the speed-load dependent variation in octane effect of humidity to be reduced.

First claim

1 . An engine method, comprising:
selecting an initial spark timing based on engine operating parameters including estimated fuel octane; learning a spark timing adjustment based on feedback indication of knock; correcting the spark timing adjustment based on the engine operating parameters; updating the initial spark timing based on the corrected spark timing adjustment; and updating the estimated fuel octane based on the updated spark timing.

2 . The method of claim 1 , wherein the selecting is performed during a first iteration, the method further comprising, during a subsequent iteration, selecting the initial spark timing based on the updated fuel octane estimate.

3 . The method of claim 1 , wherein the engine operating parameters include one or more of an engine speed and load, EGR, and an ambient humidity.

4 . The method of claim 1 , wherein the selecting includes selecting the initial spark timing based on a first relationship with the engine operating parameters, and wherein the correcting includes correcting the spark timing adjustment based on a second relationship with the engine operating parameters, the second relationship different from the first relationship.

5 . The method of claim 1 , wherein the selecting an initial spark timing based on engine operating parameters is performed at a first rate, and wherein the correcting the spark timing adjustment based on the engine operating parameters is performed at a second rate, the second rate slower than the first rate.

6 . The method of claim 1 , wherein updating the estimated fuel octane based on the updated spark timing includes updating based on a difference between the updated spark timing and the initial spark timing.

7 . The method of claim 1 , further comprising, adjusting one or more of the engine operating parameters based on the updated fuel octane estimate.

8 . The method of claim 7 , wherein the one or more engine operating parameters include a fuel injection amount and boost pressure.

9 . The method of claim 1 , wherein correcting the spark timing adjustment based on the engine operating parameters includes learning a correction factor as a function of at least one of humidity and EGR.

10 . A method for an engine, comprising:
generating each of a base spark timing and borderline spark value based on engine operating parameters including engine speed, load, EGR, and humidity and further based on an initial fuel octane estimate; adjusting the base spark timing and borderline spark value responsive to knock; further adjusting the base spark timing and borderline spark value with a correction factor based on the engine operating parameters; and updating the initial fuel octane estimate based on the adjusted spark timing.

11 . The method of claim 10 , wherein the knock is indicated based on output from one or more of an in-cylinder pressure, a knock sensor, and an ionization sensor.

12 . The method of claim 10 , wherein adjusting the base spark timing and borderline spark value responsive to knock includes retarding spark timing from the base spark timing, and advancing borderline spark towards MBT.

13 . The method of claim 10 , further comprising, during a subsequent iteration, generating the base spark timing based on the updated fuel octane estimate.

14 . The method of claim 10 , wherein the correction factor is learned as a function of at least one of ambient humidity and EGR.

15 . The method of claim 14 , wherein the correction factor is decreased as the ambient humidity increases.

16 . The method of claim 10 , further comprising, adjusting one or more engine operating parameters including fuel injection amount and EGR based on the updated fuel octane estimate

17 . A vehicle system, comprising:
an engine; a turbocharger for provided a boosted charge to the engine; a humidity sensor for estimating an ambient humidity; a knock sensor for indicating engine knock; a fuel injector for delivering fuel into an engine cylinder; and a controller with computer-readable instructions stored on non-transitory memory for:
in response to a torque demand,
generating an initial combustion profile including an initial fuel injection amount and an initial spark timing based on each of engine speed-load, ambient humidity, an octane rating of the fuel, and a feed-forward indication of knock;
correcting the spark timing with an adjustment based on a knock history of the engine;
learning an adaptation based on a difference between the initial spark timing and the corrected spark timing adjustment; and
modifying the adaptation based on ambient humidity; and
updating the octane rating of the fuel based on the modified adaptation; and
adjusting the initial combustion profile based on the updated fuel octane rating.

18 . The system of claim 17 , wherein modifying the adaptation based on ambient humidity includes modifying with a modifier based on ambient humidity, the modifier including an adder and/or a multiplier.

19 . The system of claim 18 , wherein the controller includes further instructions for learning the modifier as a function of ambient humidity, the modifier decreased as the ambient humidity increases.

20 . The system of claim 17 , wherein adjusting the initial combustion profile includes adjusting each of the initial fuel injection amount and the initial spark timing, and further adjusting a borderline spark setting.

Assignees

• Ford Global Tech Llc

Inventors

• Hakeem Mohannad Abdullah
• Surnilla Gopichandra
• Rumpsa Todd Anthony
• Ruona William Charles

Classifications

• F02P5/045 Primary

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

• F02D35/027 Primary

  using knock sensors · CPC title

• F02D2200/0418

  Air humidity · CPC title

• F02D41/0025

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

• F02P5/152

  dependent on pinking (detecting or indicating knocks in internal-combustion engines G01L23/22) · CPC title