Method of controlling engagement of a starting clutch in an automatic transmission during vehicle launch

• US 20050221958A1
• Filed: 03/31/2004
• Published: 10/06/2005
• Est. Priority Date: 03/31/2004
• 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: Lee, Chunhao J., Hebbale, Kumaraswamy V.
• Granted Patent: US 7,044,888 B2
• Time in Patent Office: Days
• US Class Current: 477/167
• CPC Class Codes: F16D 2500/30406 Clutch slip
• CPC Class Codes: F16D 2500/3063 Engine fuel flow rate
• CPC Class Codes: F16D 2500/3065 Torque of the engine
• CPC Class Codes: F16D 2500/3144 Accelerator pedal position
• CPC Class Codes: F16D 2500/50224 Drive-off
• CPC Class Codes: F16D 2500/70406 Pressure
• CPC Class Codes: F16D 2500/7061 Feed-back
• CPC Class Codes: F16D 2500/70631 Feed-forward
• CPC Class Codes: F16D 48/08 Regulating clutch take-up on starting
• CPC Class Codes: F16H 2306/30 characterised by the way or trajectory to a new ratio, e.g. by performing shift according to a particular algorithm or function determining the way or trajectory to a new ratio F16H2302/00
• CPC Class Codes: F16H 2312/02 Driving off

Abstract

A control strategy is provided for controlling engagement of a clutch during vehicle launch. A feed-back input command and a feed-forward input command are utilized and summed to determine a clutch control command. The feed back input command uses a reference slip profile having a low speed portion and a high speed portion. In the low speed portion, the slip is a function of engine speed. In the high speed portion, the slip is a function of transmission output speed or vehicle speed.

Claims

1. A method of controlling engagement of a starting clutch for a transmission connected to an engine, the method comprising:

providing a feed-forward input command as a function of an engine operating parameter;

providing a feed-back input command as a function of measured clutch slip determined from transmission input speed and transmission output speed; and

summing said feed-forward input command and said feed-back input command to determine a clutch control command for controlling engagement of the starting clutch.

2. The method of claim 1, wherein said engine operating parameter is selected from the group consisting of throttle position, gas pedal position, and calculated engine torque.

3. The method of claim 1, wherein said step of providing a feed-back input command further comprises:

comparing said measured clutch slip with a reference slip profile which includes a low speed stage in which slip is a function of engine speed such that slip increases along with engine speed to allow the engine to quickly achieve high torque, and a high speed stage in which slip is a function of vehicle speed such that slip decreases as vehicle speed increases until a final desired relatively low slip is reached; and

providing the feed-back input command based upon said comparison with the reference slip profile.

4. The method of claim 1, wherein said starting clutch is a range clutch positioned inside the transmission and is engaged in a first speed ratio, and the transmission is characterized by the absence of a torque converter.

5. The method of claim 1, wherein said starting clutch is a range clutch positioned inside the transmission and is engaged in a reverse speed ratio, and the transmission is characterized by the absence of a torque converter.

6. The method of claim 1, wherein the starting clutch is an input clutch positioned between the engine and the transmission, and the transmission is characterized by the absence of a torque converter.

7. The method of claim 3, wherein said feed-back input command and said feed-forward input command commence when vehicle speed increases from zero.

8. The method of claim 1, wherein said clutch control command controls the hydraulic force applied within the starting clutch.

9. A method of controlling engagement of a starting clutch for a transmission connected to an engine, the method comprising:

providing a feed-forward input command as a function of an engine operating parameter;

measuring clutch slip;

comparing said measured clutch slip with a reference slip profile to provide a feed-back input command; and

summing said feed-forward input command and said feed-back input command to determine a clutch control command for controlling engagement of the starting clutch.

10. The method of claim 9, wherein said engine operating parameter is selected from the group consisting of throttle position, gas pedal position, and calculated engine torque.

11. The method of claim 9, wherein said reference slip profile includes a low speed stage in which slip is a function of engine speed such that slip increases along with engine speed during launch to allow the engine to quickly achieve high torque, and a high speed stage in which slip is a function of vehicle speed such that slips decreases as vehicle speed increases until a final desired relatively low slip is reached.

12. The method of claim 11, wherein said starting clutch is a range clutch positioned inside the transmission and is engaged in first and reverse speed ratios, and the transmission is characterized by the absence of a torque converter.

13. The method of claim 11, wherein the starting clutch is an input clutch positioned between the engine and the transmission, and the transmission is characterized by the absence of a torque converter.

14. The method of claim 11, wherein said feed-back input command and said feed-forward input command commence when vehicle speed increases from zero.

15. The method of claim 9, wherein said clutch control command controls the hydraulic force applied within the starting clutch.

16. A method of controlling engagement of a starting clutch for a transmission connected to an engine having a throttle, wherein the transmission is characterized by the absence of a torque converter, the method comprising:

providing a feed-forward input command as a function of position of the throttle;

providing a feed-back input command based upon a measured clutch slip determined from transmission input speed and transmission output speed;

summing said feed-forward input command and said feed-back input command to determine a clutch control command for controlling engagement of the starting clutch;

wherein said step of providing a feed-back input command further comprises;

comparing said measured clutch slip with a reference slip profile which includes a low speed stage in which slip is a function of engine speed such that slip increases along with engine speed to allow the engine to quickly achieve high torque, and a high speed stage in which slip is a function of vehicle speed such that slip decreases as vehicle speed increases until a final desired relatively low slip is reached; and

providing the feed-back input command based upon said comparison with the reference slip profile; and

wherein the starting clutch is an input clutch positioned between the engine and the transmission.

17. The method of claim 16, wherein said feed-back input command and said feed-forward input command commence when vehicle speed increases from zero.