Up-shift control in an automatic transmission with negative input torque
View Patent ↗A transmission control module including a shift control module that generates an enable signal when an up-shift is requested and the engine torque is below a threshold torque value. A turbine speed profile determination module that selectively generates a desired turbine speed profile. The shift control module controls a clutch pressure of an off-going clutch based on a measured turbine speed and the desired turbine speed profile when the enable signal is generated.
1. A transmission control module having a processor, the transmission control module comprising:
a shift control module that generates an enable signal in response to an up-shift being requested and engine torque being below a threshold torque value, wherein generating the enable signal is suspended in response to the engine torque being above the threshold torque value; and
a turbine speed profile determination module that selectively generates a desired turbine speed profile,
wherein, in response to the enable signal being generated, the shift control module controls a clutch pressure of an off-going clutch based on a measured turbine speed and the desired turbine speed profile.
2. The transmission control module of claim 1 wherein the shift control module minimizes a difference between the measured turbine speed and the desired turbine speed profile in response to slip of the off-going clutch being detected.
3. The transmission control module of claim 2 wherein the shift control module decreases the clutch pressure at a predetermined rate until slip of the off-going clutch is detected.
4. The transmission control module of claim 2 wherein the shift control module detects slip of the off-going clutch based on a decrease in the measured turbine speed.
5. The transmission control module of claim 3 wherein the shift control module holds the clutch pressure for a predetermined period after detecting slip of the off-going clutch and before control based on the desired turbine speed profile begins.
6. The transmission control module of claim 1 further comprising an error control module that determines an offset value based on a difference between the desired turbine speed profile and the measured turbine speed, wherein the shift control module adjusts the clutch pressure based on the offset value.
7. The transmission control module of claim 6 wherein the offset value is a pressure value and the shift control module controls the clutch pressure based on a sum of the offset value and an open-loop pressure value.
8. The transmission control module of claim 1 wherein the requested up-shift is from a first gear to a second gear and wherein the shift control module decreases the clutch pressure at a predetermined rate in response to the measured turbine speed reaching a synchronization speed corresponding to the second gear.
9. The transmission control module of claim 1 wherein the threshold torque value is less than or equal to zero.
10. The transmission control module of claim 1 wherein the shift control module generates a control signal for a first solenoid to control the clutch pressure.
11. A method for controlling an up-shift in an automatic transmission, the method comprising:
generating, using a processor, an enable signal in response to an up-shift being requested and engine torque being below a threshold torque value, wherein generation of the enable signal is suspended in response to the engine torque being above the threshold torque value;
selectively generating a desired turbine speed profile; and
in response to the enable signal being generated, controlling a clutch pressure of an off-going clutch based on a measured turbine speed and the desired turbine speed profile.
12. The method of claim 11 further comprising, in response to detecting slip of the off-going clutch, minimizing a difference between the measured turbine speed and the desired turbine speed profile.
13. The method of claim 12 further comprising decreasing the clutch pressure at a predetermined rate until slip of the off-going clutch is detected.
14. The method of claim 12 further comprising detecting slip of the off-going clutch based on a decrease in the measured turbine speed.
15. The method of claim 13 further comprising holding the clutch pressure for a predetermined period after detecting slip of the off-going clutch and before control based on the desired turbine speed profile begins.
16. The method of claim 11 further comprising:
determining an offset value based on a difference between the desired turbine speed profile and the measured turbine speed; and
adjusting the clutch pressure based on the offset value.
17. The method of claim 16 further comprising controlling the clutch pressure based on a sum of the offset value and an open-loop pressure value, wherein the offset value is a pressure value.
18. The method of claim 11 wherein the requested up-shift is from a first gear to a second gear, the method further comprising decreasing the clutch pressure at a predetermined rate in response to the measured turbine speed reaching a synchronization speed corresponding to the second gear.
19. The method of claim 11 wherein the threshold torque value is less than or equal to zero.
20. The method of claim 11 further comprising generating a control signal for a first solenoid to control the clutch pressure.