A hybrid vehicle drive system including (a) an engine, (b) an electric motor,
(c)
a planetary gear device having a first rotary element connected to the engine,
a second rotary element connected to the electric motor and connected through a
first clutch to an output member connected to vehicle drive wheel, and a third
rotary element connected through a second clutch to the output member, (d) a forward-motor-drive
control device for engaging the first clutch and releasing the second clutch to
thereby establish a forward motor drive mode in which the vehicle is driven in
a forward direction by the electric motor, (e) a forward-engine-drive control device
for engaging at least the second clutch to establish an engine-drive mode in which
the vehicle is driven in the forward direction by the engine, and (f) a second-clutch
control device operable upon switching of a vehicle drive mode from the forward
motor drive mode to the forward engine drive mode, for engaging the second clutch
only after the engine speed has exceeded the motor speed.