| 摘要 |
<p>A powershift transmission (14) of an engine-driven vehicle includes input (12) and output (16) shafts, a plurality of fluid pressure operated clutches (18-24) for controlling flow of torque through the transmission and pressure control valves (130) for controlling fluid pressure communicated to the clutches. A method of controlling an off-going clutch during a shift of the transmission includes detecting a load on the engine, as a function of the detected load, determining a slip pressure, which when applied to the clutch would cause the clutch to slip, and applying the slip pressure to the clutch. If the clutch is not slipping, the pressure applied to the clutch is reduced until relative rotation (slip) between the input and output elements of said clutch is detected. Then a pressure increase is determined, which when applied to the slipping clutch would allow the slipping clutch to continue to slip while transmitting the same torque it was transmitting before it began to slip. Finally, this pressure increase is applied to the slipping clutch. <IMAGE></p> |
