Hybrid electric vehicle engine start control

摘要

A control method and control system for a hybrid electric vehicle powertrain with a multiple-ratio transmission are disclosed in which engine start events are separated in time from transmission ratio shift events to effect a smooth transition from an electric drive state with a motor-generator 12 supplying torque and with the engine 10 off to a drive state in which the engine 10 delivers driving power. The vehicle is typically a parallel hybrid. A control algorithm may include prediction steps (116, 118 see fig 9) which take account of desired transmission input power, an engine on power threshold, estimated vehicle speed at a next ratio shift and an estimated vehicle acceleration.