CONTROL SYSTEM AND METHOD FOR IDLE SPEED CONTROL TORQUE RESERVE REDUCTION

• US 20110041802A1
• Filed: 08/21/2009
• Published: 02/24/2011
• Est. Priority Date: 08/21/2009
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Kar, Krishnendu, Baibak, Daniel Lee
• Granted Patent: US 8,364,381 B2
• Time in Patent Office: Days
• US Class Current: 123/352
• CPC Class Codes: F02D 31/003 for idle speed control
• CPC Class Codes: F02D 41/1497 With detection of the mechanical response of the engine
• CPC Class Codes: F02P 5/045 combined with electronic control of other engine functions, e.g. fuel injection in general F02D37/02
• CPC Class Codes: F02P 5/152 dependent on pinking detecting or indicating knocks in internal-combustion engines G01L23/22

Abstract

A control system for an engine includes a speed error determination module that periodically determines an engine speed error rate based on a difference between a measured speed and a desired speed of the engine, and a torque reserve module that monitors the engine speed error rate and that selectively adjusts a torque reserve of the engine based on the engine speed error rate. The torque reserve module maintains the torque reserve at a predetermined first torque reserve amount while the engine speed error rate is less than a predetermined first error rate and selectively increases the torque reserve above the first torque reserve amount when the engine speed error rate increases above a predetermined second error rate greater than the first error rate. The torque reserve module decreases the torque reserve when the engine speed error rate decreases below the first error rate. A related method is also provided.

Claims

1. A control system for an engine comprising:

a speed error determination module that periodically determines an engine speed error rate based on a difference between a measured speed of said engine and a desired speed of said engine; and

a torque reserve module that monitors said engine speed error rate and that selectively adjusts a torque reserve of said engine based on said engine speed error rate.

2. The control system of claim 1 wherein said torque reserve module maintains said torque reserve at a predetermined first torque reserve amount while said engine speed error rate is less than a predetermined first error rate, and wherein said torque reserve module selectively increases said torque reserve above said first torque reserve amount when said engine speed error rate increases above a predetermined second error rate greater than said first error rate.

3. The control system of claim 2 wherein said torque reserve module selectively increases said torque reserve at a predetermined first torque rate while said engine speed error rate remains greater than said first error rate.

4. The control system of claim 3 wherein said torque reserve module limits said torque reserve to a predetermined second torque reserve amount greater than said first torque reserve amount.

5. The control system of claim 3 wherein said torque reserve module decreases said torque reserve at a predetermined second torque rate when said engine speed error rate decreases below said first error rate.

6. The control system of claim 2 wherein said first torque reserve amount is based on a density of intake air of said engine.

7. The control system of claim 2 wherein said torque reserve module increases said torque reserve above said first torque reserve amount when enablement conditions are met, and wherein said enablement conditions include one of a group consisting of said measured speed of said engine, an engine coolant temperature, a vehicle speed, and a misfire condition of said engine.

8. The control system of claim 1 wherein said torque reserve module selectively adjusts said torque reserve between a predetermined first torque reserve amount and a sum of said first torque reserve amount and a predetermined second torque reserve amount during a first period beginning when said engine speed error rate increases above a predetermined first error rate and ending when said engine speed error rate decreases below a predetermined second error rate less than said first error rate and during a second period after said first period.

9. The control system of claim 1 wherein said engine speed error rate is determined every firing period of said engine.

10. The control system of claim 1 wherein said difference is a filtered difference, and wherein said engine speed error rate is a filtered engine speed error rate.

11. A method for an engine comprising:

periodically determining an engine speed error rate based on a difference between a measured speed of said engine and a desired speed of said engine;

monitoring said engine speed error rate; and

selectively adjusting a torque reserve of said engine based on said engine speed error rate.

12. The method of claim 11 wherein said selectively adjusting a torque reserve includes maintaining said torque reserve at a predetermined first torque reserve amount while said engine speed error rate is less than a predetermined first error rate, and selectively increasing said torque reserve above said first torque reserve amount when said engine speed error rate increases above a predetermined second error rate greater than said first error rate.

13. The method of claim 12 wherein said selectively increasing said torque reserve above said first torque reserve amount includes selectively increasing said torque reserve at a predetermined first torque rate while said engine speed error rate remains greater than said first error rate.

14. The method of claim 13 wherein said selectively increasing said torque reserve above said first torque reserve amount includes limiting said torque reserve to a predetermined second torque reserve amount greater than said first torque reserve amount.

15. The method of claim 13 further comprising decreasing said torque reserve at a predetermined second torque rate when said engine speed error rate decreases below said first error rate.

16. The method of claim 12 wherein said first torque reserve amount is based on a density of intake air of said engine.

17. The method of claim 12 wherein said selectively increasing said torque reserve above said first torque reserve amount includes increasing said torque reserve above said first torque reserve amount when enablement conditions are met, and wherein said enablement conditions include one of a group consisting of said measured speed of said engine, an engine coolant temperature, a vehicle speed, and a misfire condition of said engine.

18. The method of claim 11 wherein said selectively adjusting a torque reserve of said engine includes increasing said torque reserve between a predetermined first torque reserve amount and a sum of said first torque reserve amount and a predetermined second torque reserve amount during a first period beginning when said engine speed error rate increases above a predetermined first error rate and ending when said engine speed error rate decreases below a predetermined second error rate less than said first error rate, and decreasing said torque reserve during a second period after said first period.

19. The method of claim 11 wherein said engine speed error rate is determined every firing period of said engine.

20. The method of claim 11 wherein said difference is a filtered difference, and wherein said engine speed error rate is a filtered engine speed error rate.