CONTROL OF ENGINE TORQUE REDUCTION AT UPSHIFT INITIATION

• US 20080081735A1
• Filed: 10/02/2006
• Published: 04/03/2008
• Est. Priority Date: 10/02/2006
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: RUNDE, JEFFREY K.
• Granted Patent: US 7,651,440 B2
• Time in Patent Office: Days
• US Class Current: 477/107
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/115 with planetary gears
• CPC Class Codes: B60W 2050/0031 Mathematical model of the vehicle
• CPC Class Codes: B60W 30/19 Improvement of gear change, e.g. by synchronisation or smoothing gear shift
• CPC Class Codes: F16H 2302/00 Determining the way or trajectory to new ratio, e.g. by determining speed, torque or time parameters for shift transition
• 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
• CPC Class Codes: F16H 61/061 using electric control means
• CPC Class Codes: F16H 61/686 with orbital gears
• CPC Class Codes: F16H 63/502 for smoothing gear shifts
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An improved control for an automatically shiftable transmission upshift, wherein the engine output torque and on-coming clutch pressure are coordinated during the shift based on an inverse dynamic model of the transmission to achieve a desired output torque trajectory. At the initiation of an upshift, the engine torque is commanded to decrease in a ramp-like or sloping fashion to and engine output torque value calculated using the dynamic model. This ramp-like or sloping decrease provides smooth shifting, while reducing the likelihood of tie-up between on-coming and off-going clutches within the automatically shiftable transmission.

Claims

1. A method of controlling torque of an engine operatively connected to an automatically shiftable transmission during shifting of the automatically shiftable transmission, the method comprising:

determining an engine output torque command value; and

commanding an output torque of the engine in a ramp-like or sloping torque reduction to said engine output torque command value during shifting of the automatically shiftable transmission.

2. The method of claim 1, wherein said ramp-like or sloping torque reduction has a slope of between −

1 Nm per second to −

800 Nm per second.

3. The method of claim 1, further comprising commanding said output torque of the engine to increase after the shifting has occurred.

4. The method of claim 1, wherein determining said engine output torque command value includes:

determining a desired torque trajectory of an output shaft of the automatically shiftable transmission;

determining a desired acceleration trajectory of an input shaft of the automatically shiftable transmission; and

applying said desired torque trajectory and said desired acceleration trajectory to an inverse dynamic model of the automatically shiftable transmission to determine said engine output torque command value.

5. The method of claim 1, wherein the shifting of the automatically shiftable transmission includes the engagement of an on-coming clutch and wherein the on-coming clutch engagement includes a fill phase, the method further comprising commanding said ramp-like or sloping torque reduction to begin prior to initiation of the fill phase.

6. The method of claim 1, wherein the shifting of the automatically shiftable transmission includes the engagement of an on-coming clutch and wherein the on-coming clutch engagement includes a fill phase, the method further comprising commanding said ramp-like or sloping torque reduction to begin after initiation of the fill phase.

7. The method of claim 1, wherein the shifting of the automatically shiftable transmission includes the engagement of an on-coming clutch and wherein the on-coming clutch engagement includes an inertial phase where the on-coming clutch gains capacity, the method further comprising commanding said ramp-like or sloping torque reduction to end substantially at the initiation of the inertial phase.

8. The method of claim 4, wherein applying said desired torque trajectory and said desired acceleration trajectory to said inverse dynamic model to determine said engine output torque command includes:

determining a desired output acceleration trajectory based on said desired output torque trajectory; and

applying said desired output acceleration trajectory, said desired torque trajectory and said desired input acceleration trajectory to said inverse dynamic model to determine said engine output torque command.

9. A method of controlling an on-coming clutch pressure and engine output torque during an upshift of an automatically shiftable transmission of a vehicle having an input shaft coupled to an engine and an output shaft coupled to drive the vehicle, the method comprising:

determining a desired torque trajectory of the output shaft;

determining a desired acceleration trajectory of the input shaft;

applying said desired torque trajectory and said desired acceleration trajectory to an inverse dynamic model of the automatically shiftable transmission to determine an engine output torque command value;

commanding engine output torque in a ramp-like or sloping torque reduction in accordance with said engine output torque command value;

applying said desired acceleration trajectory to said inverse dynamic model of the automatically shiftable transmission during an inertial phase of the upshift to obtain an estimated on-coming clutch torque at the commanded engine output torque;

determining a feed-forward clutch pressure command based on said estimated on-coming clutch torque requirement;

determining and on-coming clutch pressure command in accordance with the feed-forward pressure command; and

commanding the on-coming clutch in accordance with said on-coming clutch pressure command.

10. The method of claim 9, wherein applying said desired acceleration trajectory to the inverse dynamic model of the transmission includes:

delaying said commanded engine output torque and said desired acceleration trajectory to determine a delayed desired acceleration trajectory and a delayed commanded engine output torque, respectively; and

applying said delayed desired acceleration trajectory and said delayed commanded engine output torque to said inverse dynamic model to obtain said estimated on-coming clutch torque.

11. The method of claim 9, further comprising:

determining a measured speed of the input shaft;

determining an expected speed of the input shaft; and

adjusting said on-coming clutch pressure command in accordance with a feed-back adjustment based on a deviation of said measured speed from said expected speed to compensate for errors in said dynamic model.

12. The method of claim 11, wherein determining said expected speed of the input shaft includes:

delaying said output torque trajectory to estimate an expected output torque;

determining an expected input acceleration based on said expected output torque and said engine output torque; and

integrating said expected input acceleration to determine said expected speed of the input shaft.

13. The method of claim 9, wherein applying said desired torque trajectory and said desired acceleration trajectory to said inverse dynamic model of the automatically shiftable transmission to determine said engine output torque command includes:

determining a desired output acceleration trajectory based on said desired output torque trajectory; and

applying said desired output acceleration trajectory, said desired torque trajectory, and said desired input acceleration trajectory to said inverse dynamic model to determine said engine output torque command.

14. A method of controlling engine output torque during an upshift of an automatically shiftable transmission of a vehicle having an input shaft coupled to an engine and an output shaft coupled to drive the vehicle, the method comprising:

determining a desired torque trajectory of the output shaft;

determining a desired acceleration trajectory of the input shaft;

applying said desired torque trajectory and said desired acceleration trajectory to an inverse dynamic model of the automatically shiftable transmission to determine an engine output torque command value;

commanding engine output torque in a ramp-like or sloping torque reduction in accordance with said engine output torque command value; and

wherein said ramp-like or sloping torque reduction has a slope of between −

1 Nm per second to −

800 Nm per second.