Clutch torque trajectory correction to provide torque hole filling during a ratio upshift

Abstract

A multiple ratio transmission having an input shaft, an output shaft and oncoming clutch and off-going clutch for effecting ratio upshifts is provided. The transmission also includes a transmission controller configured for controlling shifts. During the torque phase of a ratio upshift, the controller increases input torque. Next, the controller estimates an oncoming clutch target torque. The controller controls a torque input to ensure the off-going clutch remains locked. The controller measures an actual transmission value for a torque transmitting element of the transmission and corrects the oncoming clutch target torque using the actual transmission value whereby an increasing torque for the oncoming friction element is achieved with minimal torque transients along the output shaft during the upshift.

1 .- 20 . (canceled) 
     
     
         21 . A computer-program product embodied in a non-transitory computer readable medium that is programmed for controlling a transmission a ratio upshift, the computer-program product comprising instructions for:
 receiving a measured torque signal based on a measured torque of a torque transmitting element of the transmission; and   in response to the measured torque signal, modulating a torque capacity of an on-coming friction element to achieve a target torque capacity.   
     
     
         22 . The computer-program product of  claim 21  further comprising instructions for:
 calculating an instantaneous torque of the on-coming friction element from the measured torque signal; and 
 modulating a torque capacity of an on-coming friction element by applying a feedback correction if the calculated instantaneous torque differs from a theoretical torque that increases while the on-coming friction element ramps towards the target torque capacity. 
 
     
     
         23 . The computer-program product of  claim 21  further comprising instructions for:
 receiving the measured torque signal from a torque sensor that measures a torque transmitting element of the transmission. 
 
     
     
         24 . The computer-program product of  claim 23  wherein the sensor measures torque at one of the input shaft and output shaft. 
     
     
         25 . The computer-program product of  claim 21  further comprising instructions for:
 maintaining an off-going friction element locked while ramping the on-coming friction element towards the target toque capacity. 
 
     
     
         26 . The computer-program product of  claim 21  further comprising instructions for:
 calculating a torque of the off-going friction element from the measured torque signal; 
 wherein if the off-going friction element torque is less than a threshold value, releasing the off-going clutch to complete the upshift. 
 
     
     
         27 . A control system for a transmission comprising:
 a shift controller programmed to:   while ramping the on-coming friction element towards a target toque capacity after the upshift, correct an instantaneous torque of the on-coming friction element in response to a measured torque signal; and   maintain an off-going friction element locked while ramping the on-coming friction element.   
     
     
         28 . The control system of  claim 27  wherein the controller is further programmed to:
 receive the measured torque signal from a torque sensor that measures a torque transmitting element of the transmission. 
 
     
     
         29 . The control system of  claim 28  wherein a torque sensor provides the measured torque signal indicative of a measure torque at one of an input shaft and an output shaft. 
     
     
         30 . The control system of  claim 27  wherein the controller is programmed to:
 calculate the instantaneous torque of the on-coming friction element from the measured torque signal, 
 wherein correcting the instantaneous torque of the on-coming friction element includes applying a feedback correction if the calculated instantaneous torque differs from a theoretical torque that increases while the on-coming friction element ramps towards the target torque capacity. 
 
     
     
         31 . The control system of  claim 27  wherein the controller is programmed to:
 calculate a torque of the off-going friction element from the measured torque signal; and 
 wherein if the off-going friction element torque is less than a threshold value, release the off-going clutch to complete the upshift. 
 
     
     
         32 . The control system of  claim 27  wherein the controller is programmed to:
 choose the target torque capacity of the on-going friction element based on at least one of a desired input shaft torque and a desired output shaft torque. 
 
     
     
         33 . The control system of  claim 27  wherein correcting the torque capacity of the on-coming friction element modulates the torque capacity of the on-coming friction element during the upshift. 
     
     
         34 . The control system of  claim 27  wherein the shift controller is further programmed to:
 choose the target torque capacity is based on a target output shaft torque. 
 
     
     
         35 . A method for controlling a transmission during an upshift comprising:
 choosing a target torque capacity of the on-coming friction element after the upshift; and   maintaining an off-going friction element locked while ramping the on-coming friction element to the target torque capacity;   while ramping the on-coming friction element, applying a feedback correction of an instantaneous torque of the on-coming friction element in response to a measured torque signal.   
     
     
         36 . The method of  claim 35  wherein the measured torque signal is provided by a sensor disposed at one of the input shaft and output shaft, the method further comprising calculating the instantaneous torque of the on-coming friction element using a gear-ratio and the measure torque signal. 
     
     
         37 . The method of  claim 35  further comprising:
 calculating the instantaneous torque of the on-coming friction element from the measured torque signal, 
 wherein the feedback correction is applied if the calculated instantaneous torque differs from a theoretical torque that increases while the on-coming friction element ramps towards the target torque capacity. 
 
     
     
         38 . The method of  claim 35  further comprising:
 calculating a torque of the off-going friction element from the measured torque signal; and 
 releasing the off-going clutch to complete the upshift if the off-going friction element torque is less than a threshold value. 
 
     
     
         39 . The control system of  claim 35  wherein correcting the torque capacity of the on-coming friction element modulates the torque capacity of the on-coming friction element during the upshift. 
     
     
         40 . The control system of  claim 35  wherein choosing the target torque capacity is based on a target output shaft torque.