SYSTEM AND METHOD FOR CONTROLLING A TRANSMISSION TO IMPROVE EXHAUST BRAKING

• US 20120101700A1
• Filed: 10/20/2010
• Published: 04/26/2012
• Est. Priority Date: 10/20/2010
• 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: Mitchell, Andrew L., Kluemper, Kevin L., Caldwell, Brett R.
• Granted Patent: US 8,612,106 B2
• Time in Patent Office: Days
• US Class Current: 701/58
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2520/105 Longitudinal acceleration
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 2710/1005 Transmission ratio engaged
• CPC Class Codes: B60W 2720/10 Longitudinal speed
• CPC Class Codes: B60W 30/143 Speed control B60W30/16 takes precedence
• CPC Class Codes: B60W 30/18136 Engine braking
• CPC Class Codes: F16H 2061/0232 Selecting ratios for bringing engine into a particular state, e.g. for fast warming up or for reducing exhaust emissions
• CPC Class Codes: F16H 59/44 dependent on machine speed of the machine, e.g. the vehicle
• CPC Class Codes: F16H 61/0213 characterised by the method for generating shift signals
• CPC Class Codes: F16H 61/21 Providing engine brake control

Abstract

A system for controlling a transmission of a vehicle powered by an engine includes a torque determination module and a shift determination module. The torque determination module determines a desired exhaust brake torque for the engine based on an actual speed of the vehicle and a desired speed of the vehicle. The shift determination module determines whether to shift between gear ratios of the transmission based on the desired exhaust brake torque and an exhaust brake torque capacity of the engine.

Claims

1. A system for controlling a transmission of a vehicle powered by an engine, comprising:

a torque determination module that determines a desired exhaust brake torque for the engine based on an actual speed of the vehicle and a desired speed of the vehicle; and

a shift determination module that determines whether to shift between gear ratios of the transmission based on the desired exhaust brake torque and an exhaust brake torque capacity of the engine.

2. The system of claim 1, further comprising:

a speed determination module that determines the desired speed of the vehicle based on a cruise control speed input by a driver of the vehicle.

3. The system of claim 1, further comprising:

a speed determination module that determines the desired speed of the vehicle based on driver input during a predetermined period, wherein the driver input includes acceleration and braking of the vehicle.

4. The system of claim 3, wherein the desired speed decreases based on braking of the vehicle, and wherein the desired speed increases and tracks the vehicle speed based on acceleration of the vehicle.

5. The system of claim 1, wherein the shift determination module upshifts between gear ratios of the transmission when vehicle acceleration is greater than a vehicle acceleration threshold or when exhaust brake torque after an upshift is less than the exhaust brake torque capacity of the engine.

6. The system of claim 5, wherein the shift determination module decrements a shift counter after an upshift between gear ratios of the transmission.

7. The system of claim 6, wherein the shift determination module maintains a current gear ratio of the transmission when the desired exhaust brake torque is less than a predetermined percentage of the exhaust brake torque capacity of the engine or when a difference between the actual and desired speeds of the vehicle is less than a predetermined speed threshold.

8. The system of claim 7, wherein the shift determination module downshifts between gear ratios of the transmission when the desired exhaust brake torque is greater than the predetermined percentage of the exhaust brake torque capacity of the engine and the difference between the actual and desired vehicle speeds is greater than the predetermined speed threshold.

9. The system of claim 8, wherein the shift determination module increments the shift counter after a downshift between gear ratios of the transmission.

10. The system of claim 9, wherein the predetermined speed threshold is based on at least one of a transmission range associated with a current gear ratio of the transmission and the shift counter.

11. A method for controlling a transmission of a vehicle powered by an engine, comprising:

determining a desired exhaust brake torque for the engine based on an actual speed of the vehicle and a desired speed of the vehicle; and

determining whether to shift between gear ratios of the transmission based on the desired exhaust brake torque and an exhaust brake torque capacity of the engine.

12. The method of claim 11, further comprising determining the desired speed of the vehicle based on a cruise control speed input by a driver of the vehicle.

13. The method of claim 11, further comprising determining the desired speed of the vehicle based on driver input during a predetermined period, wherein the driver input includes acceleration and braking of the vehicle.

14. The method of claim 13, wherein the desired speed decreases based on braking of the vehicle, and wherein the desired speed increases and tracks the vehicle speed based on acceleration of the vehicle.

15. The method of claim 11, further comprising upshifting between gear ratios of the transmission when vehicle acceleration is greater than a vehicle acceleration threshold or when exhaust brake torque after an upshift is less than the exhaust brake torque capacity of the engine.

16. The method of claim 15, further comprising decrementing a shift counter after an upshift between gear ratios of the transmission.

17. The method of claim 16, further comprising maintaining a current gear ratio of the transmission when the desired exhaust brake torque is less than a predetermined percentage of the exhaust brake torque capacity of the engine or when a difference between the actual and desired speeds of the vehicle is less than a predetermined speed threshold.

18. The method of claim 17, further comprising downshifting between gear ratios of the transmission when the desired exhaust brake torque is greater than the predetermined percentage of the exhaust brake torque capacity of the engine and the difference between the actual and desired vehicle speeds is greater than the predetermined speed threshold.

19. The method of claim 18, further comprising incrementing the shift counter after a downshift between gear ratios of the transmission.

20. The method of claim 19, wherein the predetermined speed threshold is based on at least one of a transmission range associated with a current gear ratio of the transmission and the shift counter.