Patent ID: 7498757

Claim:
A control device for a hybrid electric vehicle capable of transmitting a driving force of an engine and a driving force of an electric motor to driving wheels through an automatic transmission and capable of releasing mechanical connection between the engine and the automatic transmission by using a clutch, comprising: revolution speed detection means for detecting revolution speed of the electric motor; shift control means that downshifts the automatic transmission according to a reduction of traveling speed of the electric vehicle at the time of deceleration of the electric vehicle; and torque control means that sets an upper limit deceleration torque that is a deceleration torque generable by the electric motor and a required deceleration torque that is a deceleration torque to be generated by the engine and the electric motor corresponding to a forward gear presently used in the automatic transmission according to revolution speed detected by the revolution speed detection means at the time of deceleration of the electric vehicle, wherein the torque control means disengages the clutch and controls the electric motor so as to generate the required deceleration torque when the upper limit deceleration torque is equal to or larger than the required deceleration torque, and on the other hand, engages the clutch and controls the engine and the electric motor so that a sum of a deceleration torque of the engine and a deceleration torque of the electric motor equals the required deceleration torque when the upper limit deceleration torque is smaller than the required deceleration torque, wherein the upper limit deceleration torque is set so as to be equal to the required deceleration torque when the revolution speed of the electric motor is predetermined revolution speed, to be larger than the required deceleration torque in a range where the revolution speed of the electric motor is lower than the predetermined revolution speed, and to be smaller than the required deceleration torque in a range where the revolution speed of the electric motor is higher than the predetermined revolution speed; and the predetermined revolution speed for the required deceleration torque corresponding to a forward gear related to downshift of the automatic transmission is different from revolution speed that falls in a range of revolution speed fluctuation of the electric motor at the time of downshift.