US 8,968,153 B1 · Method of operating a transmission

Abstract

A method of controlling a launch clutch during an engine restart event commands a positive torque capacity before the engine reaches idle speed. Early application of the launch clutch reduces the time delay between brake pedal release and vehicle acceleration. To avoid excessive drag on the engine during the restart event, the torque capacity is adjusted using closed loop control. A controller calculates a maximum rate of change of torque capacity based on measured engine speed and an engine acceleration and does not increase the commanded torque capacity faster than the calculated rate. In some circumstances the maximum rate of change may be negative, resulting in a reduction in commanded torque capacity.

Claims16

Dependent claims

A method of operating a vehicle comprising:

engaging elements of a transmission such that the transmission applies an input torque to resist rotation of an engine and applies an output torque to a wheel, wherein the input torque and the output torque each vary in proportion to a torque capacity of a launch clutch of the transmission;
and
during a start event of the engine and while an engine speed is less than an idle speed, increasing the torque capacity of the clutch to initiate application of the input torque and the output torque to initiate acceleration of the vehicle and adjusting the torque capacity of the launch clutch based on an engine speed and an engine acceleration.

Dependencies are inferred from the claim text.

Method of operating a transmission

Life of this patent

Method of operating a transmission

Life of this patent

Abstract

Claims16