Abstract: A torque distribution method for an engine and a motor of an energy-efficient hybrid electric vehicle comprises the following steps: providing an offline specific fuel consumption map of the engine in all operating states; enabling the engine and motor to respond to the required torque T during travelling together, the motor and the engine working in cooperation at the same rotational speed so as to achieve the optimal working efficiency; acquiring a current state of charge (SOC) of the vehicle battery, and distributing the engine torque T and the motor torque T according to the following situation: if the SOC is greater than a first preset value, entering a first distribution mode; if the SOC is less than a second preset value, enter a second distribution mode; and otherwise, maintaining the current working state.

Abstract: A series/parallel hybrid electric drive unit for vehicle comprises an engine (1), a main traction motor (2), an integrated starter-generator (3), a differential (4), a first shaft (main shaft) (5), a first stage decelerating device (9), a second stage decelerating device (10), a first clutch (6), a second clutch (7) and a synchronizer (8). The synchronizer (8) is slidably arranged on the first shaft (5) which is connected to the first stage decelerating device (9) or the second stage decelerating device (10) by the synchronizer (8), respectively. The hybrid electric drive unit of the invention has a compactly-arranged internal structure and an efficient and appropriate internal connection, and a switch between connection and disconnection of respective hybrid power sources and wheels and a shifting among operating modes and gear positions of the hybrid drive system can be realized.