System and method for controlling a torque converter clutch
Methods and systems for operating a torque converter clutch of an automatic transmission are presented. In one non-limiting example, the torque converter clutch is closed to provide a threshold torque capacity during a vehicle launch. If an engine torque request is less than the threshold torque capacity, the torque converter clutch remains closed.
1. A method for operating a driveline of a vehicle, comprising:
adjusting a torque capacity of a torque converter clutch to provide a non-zero torque capacity in response to a vehicle speed of zero; and
opening the torque converter clutch in response to a transmission input torque request greater than the non-zero torque capacity after adjusting the torque capacity of the torque converter clutch to provide the non-zero torque capacity.
2. The method of claim 1 , further comprising automatically applying vehicle wheel brakes in response to the vehicle speed being less than the threshold and a driver requested torque being less than a threshold while the torque capacity of the torque converter clutch is adjusted to the non-zero torque capacity.
3. The method of claim 1 , further comprising fully opening the torque converter clutch in response to a predetermined actual total number of accelerator pedal applications and releases after adjusting the torque capacity of the torque converter clutch to provide the non-zero torque capacity.
4. The method of claim 3 , where the predetermined actual total number of accelerator pedal applications and releases occur with a threshold amount of time of each other, and wherein the non-zero torque capacity is a torque capacity sufficient to allow the vehicle to accelerate the vehicle to a desired speed in a threshold amount of time.
5. The method of claim 1 , where the transmission input torque request is based on accelerator pedal position.
6. The method of claim 1 , further comprising adjusting the torque capacity of the torque converter clutch to provide the non-zero torque capacity in further response to the transmission input torque request being less than a threshold.
7. The method of claim 1 , further comprising adjusting the torque capacity of the torque converter clutch in further response to the vehicle being in a towing mode.
8. A method for operating a vehicle driveline, comprising:
adjusting a torque capacity of a torque converter clutch to provide a torque capacity in response to vehicle speed being less than a threshold, where the torque capacity is non-zero in response to a vehicle in which the torque converter clutch resides being directed downhill.
9. The method of claim 8 , where the torque capacity of the torque converter clutch is substantially zero in response to the vehicle being directed uphill on a road having a grade greater than a threshold.
10. The method of claim 8 , further comprising adjusting the torque capacity of the torque converter clutch to substantially zero in response to the vehicle being in a tow mode and directed downhill.
11. The method of claim 8 , further comprising further adjusting the torque capacity of the torque converter clutch to provide substantially zero torque capacity in response to a plurality of torque increase requests and torque decrease requests within less than a threshold amount of time.
12. The method of claim 8 , further comprising automatically applying vehicle brakes in response to the vehicle speed being less than the threshold.
13. The method of claim 8 , further comprising opening a forward clutch of the transmission in response to the vehicle speed being less than the threshold.
14. The method of claim 13 , further comprising closing the forward clutch in response to an increase in a desired transmission input torque.
15. A method for operating a vehicle driveline, comprising:
during launch of a vehicle, providing a predetermined constant non-zero torque converter clutch capacity, and closing a forward clutch of a transmission in response to an increase in a requested transmission input torque; and
increasing engine output torque in response to the requested transmission input torque while proving the predetermined non-zero torque converter clutch capacity.
16. The method of claim 15 , where the predetermined non-zero torque converter clutch capacity is provided via closing a torque converter clutch.
17. The method of claim 15 , further comprising decreasing the predetermined non-zero converter clutch capacity in response to a transmission input torque being greater than a threshold.
18. The method of claim 15 , further comprising decreasing the predetermined non-zero converter clutch capacity in response to a transmission input torque being greater than a threshold.
19. The method of claim 18 , further comprising decreasing the predetermined non-zero converter clutch capacity in response to a plurality of transmission input torque increase requests and decrease requests.
20. The method of claim 15 , further comprising decreasing the predetermined non-zero converter clutch capacity in response to the vehicle entering a tow mode.