Patent ID: 7789798

Claim:
A method of controlling an upshift in a transmission having a main box and a compounder coupled to the main box and having at least one gearset and at least one clutch separate from the main box, the method comprising: initiating an upshift in the main box including application of at least one clutch in the main box; initiating venting of a clutch being released in the compounder during a torque phase; determining occurrence of slip in the compounder; controlling, after slip has occurred in the compounder, a duty cycle of a solenoid associated with the clutch being released in the compounder as a function of a desired acceleration of the compounder, determining a target input speed and a target compounder speed for the gear into which the transmission is being shifted; controlling a duty cycle of the solenoid of the clutch being applied when a speed of the compounder nears the target compounder speed to control the apply rate of the clutch being applied to bring an input speed to the target input speed; wherein the upshift is initiated by controlling the duty cycle of the solenoid associated with the clutch being applied providing a rapid increase in a fluid volume in the clutch that terminates when a target volume is reached; wherein the target volume gives rise to a pressure in the clutch being applied that is less than the pressure at which the clutch has capacity to take torque; controlling the duty cycle of the solenoid of the clutch being released when the compounder speed nears the compounder target speed to bring the compounder speed to the compounder target speed; and controlling the duty cycle of the solenoid of the clutch being applied when the compounder speed nears the compounder target speed is accomplished with feedback; and controlling the duty cycle of the solenoid of the clutch being released when the compounder speed nears the compounder target speed is accomplished with feed forward control.