Hybrid vehicle drive system adapted to prevent concurrent mode change and transmission shifting or torque distribution ratio change

摘要

A hybrid drive system including an engine and an electric motor at least one of which is operated as drive power source to drive a motor vehicle in a selected one of different operation modes. The system is adapted to prevent concurrent operations to change the operation mode and the speed ratio of a power transmitting device or the ratio of torque distribution to front and rear drive wheels, or concurrent operations to change the operation mode and switch the power transmitting device from a non-drive state to a drive state, for avoiding a shock due to a torque variation which would arise from the concurrent operations. The system is alternatively adapted to cut a power transfer from the drive power source to the power transmitting device, or hold the output of the drive power source substantially constant, when the power transmitting device is switched from the non-drive state to the drive state.