Transmission and method of controlling clutch during ratio change

摘要

A transmission and control method are disclosed which ensure proper stroke pressure and minimize torque transients during a shift event. The transmission includes a clutch having a torque capacity based on a fluid pressure, a torque sensor adapted to measure a torque value that varies in relationship to the torque capacity, and a controller. The method includes varying the fluid pressure around a predetermined value, measuring a resulting torque difference with the torque sensor, and adjusting a clutch control parameter if the resulting torque difference is less than a threshold value.

主权项

1. A method for controlling a transmission, the method comprising:
setting a clutch pressure for an oncoming clutch at a predetermined stroke pressure during a current downshift event; varying the clutch pressure from the predetermined stroke pressure during an inertia phase of the current downshift event; measuring a resulting torque difference along a torque transmitting element with a torque sensor while the clutch pressure is varied; and adjusting a clutch control parameter if the resulting torque difference is less than a threshold value, wherein the clutch control parameter is adjusted during one of the current downshift event and a future shift event, to ensure proper clutch stroke and minimize torque transients during a torque phase.