Patent ID: 7370715

Claim:
A method for starting an engine in a vehicle having an electric machine, a first clutch disposed between the engine and the electric machine for selectively connecting the engine to the electric machine, and a second clutch disposed between the electric machine and vehicle drive wheels, the second clutch being selectively engagable for facilitating torque transfer between the electric machine and the vehicle drive wheels, the method comprising: requesting an engine start; operating the electric machine; partially disengaging the second clutch if the second clutch is fully engaged when the engine start is requested, the partial disengagement of the second clutch causing the second clutch to slip, thereby at least partially isolating the vehicle drive wheels from engine torque disturbances; engaging the first clutch, including increasing a pressure of the first clutch to a first level, holding the pressure of the first clutch generally constant at the first level for a predetermined time, lowering the pressure of the first clutch to a second level, and increasing the pressure of the first clutch to an intermediate level between the first and second levels, thereby connecting the engine to the electric machine and engaging the first clutch with enough pressure to overcome a first compression stroke of the engine; and fueling the engine, thereby facilitating torque production by the engine.