Method and Apparatus for Starting an Engine in a Hybrid Vehicle

Abstract

A method and apparatus for starting an engine in a hybrid vehicle being driven by an electric motor is disclosed. The motor is operably configured to deliver mechanical power through an automatic transmission to at least one vehicle drive wheel to cause an acceleration of the vehicle. The method involves coupling the engine to the motor to cause an inertial load on the motor thus causing the motor to decelerate to a reduced rotational speed to provide a starting torque to the engine for starting the engine, and causing the automatic transmission to change gear ratio to a target gear ratio associated with the reduced rotational speed while causing the motor to decelerate, the motor being operable to deliver increased torque at the reduced rotational speed, thereby generally maintaining the acceleration of the vehicle.

What is claimed is: 
     
         1 . A method for starting an engine in a hybrid vehicle being driven by an electric motor, the motor being operably configured to deliver mechanical power through an automatic transmission to at least one vehicle drive wheel to cause an acceleration of the vehicle, the method comprising:
 coupling the engine to the motor to cause an inertial load on the motor thus causing the motor to decelerate to a reduced rotational speed to provide a starting torque to the engine for starting the engine; and   causing the automatic transmission to change gear ratio to a target gear ratio associated with said reduced rotational speed while causing the motor to decelerate, the motor being operable to deliver increased torque at said reduced rotational speed, thereby generally maintaining the acceleration of the vehicle.