Method and apparatus for controlling spark timing in an internal combustion engine

• US 8,555,857 B2
• Filed: 11/16/2010
• Issued: 10/15/2013
• Est. Priority Date: 11/16/2010
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Yang, Xiaofeng, Wang, Wenbo, Kuo, Tang-Wei, Kaiser, Jeffrey M., Daniels, Chao F.
• Primary Examiner(s): Cronin, Stephen K
• Assistant Examiner(s): DALLO, JOSEPH J
• Application Number:
  US12/947,103
• Publication Number:
  US 20120118266A1
• Time in Patent Office: 1,064 Days
• Field of Search: 123/329, 123/339.11, 123/406.11, 123/406.12, 12340623-40627, 123/406.33, 123/406.57, 123/406.28, 123/406.44, 123/406.45, 123/406.47, 701101-105, 701/109, 731/140.8, 731/140.9, 702/182
• US Class Current: 123/406.26
• CPC Class Codes: F02D 2200/1002 Output torque
• CPC Class Codes: F02D 35/028 by determining the combustion timing or phasing
• CPC Class Codes: F02D 41/1497 With detection of the mechanical response of the engine
• CPC Class Codes: F02P 5/04 automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions dependent on position of personal controls of engine F02P5/02

Abstract

A method for operating a spark-ignition internal combustion engine includes controlling spark ignition timing responsive to a combustion charge flame speed corresponding to an engine operating point and a commanded air/fuel ratio associated with an operator torque request.

Claims

1. A method for operating a spark-ignition internal combustion engine comprises controlling spark ignition timing by determining an initial spark timing corresponding to an engine operating point, and adjusting the initial spark timing using a spark timing compensation, where the spark timing compensation is determined by a change in combustion charge flame speed corresponding to the engine operating point and a commanded air/fuel ratio associated with an operator torque request.

2. Method for operating a spark-ignition internal combustion engine, comprising:

determining an initial spark timing corresponding to an engine operating point;

determining a commanded air/fuel ratio corresponding to an engine load;

determining a change in a combustion charge flame speed corresponding to the commanded air/fuel ratio;

determining a change in a combustion timing corresponding to the change in the combustion charge flame speed;

determining a spark timing compensation corresponding to the change in the combustion timing; and

adjusting the initial spark timing using the spark timing compensation.

3. The method of claim 2, wherein determining the change in the combustion charge flame speed corresponding to the commanded air/fuel ratio comprises:

determining a representative flame speed correlated to the commanded air/fuel ratio; and

determining an effective relative flame speed corresponding to the representative flame speed.

4. The method of claim 3, wherein determining the representative flame speed correlated to the commanded air/fuel ratio comprises determining the representative flame speed in accordance with the following relationship:

RFS=A−

B*(AF−

C)²,

wherein RFS is the representative flame speed and AF is the commanded air/fuel ratio, and A, B, and C are scalar terms.

5. The method of claim 3, wherein determining the effective relative flame speed corresponding to the representative flame speed comprises determining the effective relative flame speed in accordance with the following relationship:

6. The method of claim 2, wherein determining the change in the combustion timing corresponding to the change in the combustion charge flame speed comprises:

determining a duration between initiating a spark ignition event and a corresponding 50% mass-burn-fraction point correlated to a combustion retard;

determining a representative flame speed correlated to the commanded air/fuel ratio;

determining an effective relative flame speed corresponding to the representative flame speed; and

determining the change in the combustion timing corresponding to the effective relative flame speed and the duration between initiating the spark ignition event and the corresponding 50% mass-burn-fraction point correlated to the change in combustion timing.

7. The method of claim 2, wherein determining the commanded air/fuel ratio corresponding to the engine load comprises determining the commanded air/fuel ratio based upon an operator torque request.

8. The method of claim 2, wherein determining the change in the combustion charge flame speed corresponding to the commanded air/fuel ratio comprises determining a change in the combustion charge flame speed based upon a difference between a reference air/fuel ratio and the commanded air/fuel ratio.

9. Method for controlling a spark timing in a spark-ignition internal combustion engine, comprising:

determining a commanded air/fuel ratio corresponding to an operator torque request;

determining a change in a combustion charge flame speed corresponding to the commanded air/fuel ratio;

determining a change in a combustion timing corresponding to the change in the combustion charge flame speed;

determining a spark timing compensation corresponding to the change in the combustion timing; and

adjusting the spark timing for an engine operating point using the spark timing compensation.

10. The method of claim 9, wherein determining the change in the combustion charge flame speed corresponding to the commanded air/fuel ratio comprises:

determining a representative flame speed correlated to the commanded air/fuel ratio; and

determining an effective relative flame speed corresponding to the representative flame speed.

11. The method of claim 10, wherein determining the representative flame speed correlated to the commanded air/fuel ratio comprises determining the representative flame speed in accordance with the following relationship:

RFS=A−

B*(AF−

C)²,

wherein RFS is the representative flame speed and AF is the commanded air/fuel ratio, and A, B, and C are scalar terms.

12. The method of claim 10, wherein determining the effective relative flame speed corresponding to the representative flame speed comprises determining the effective relative flame speed in accordance with the following relationship:

13. The method of claim 9, wherein determining the change in the combustion timing corresponding to the change in the combustion charge flame speed comprises:

determining a duration between initiating a spark ignition event and a corresponding 50% mass-burn-fraction point correlated to a combustion retard;

determining a representative flame speed correlated to the commanded air/fuel ratio;

determining an effective relative flame speed corresponding to the representative flame speed; and

determining the change in the combustion timing corresponding to the effective relative flame speed and the duration between initiating the spark ignition event and the corresponding 50% mass-burn-fraction point correlated to the change in combustion timing.