Through type air cooling speed reducer assembly of electric vehicle

A through-type air-cooled speed reducer assembly of an electric vehicle comprises a motor, a speed reducer, a differential mechanism and a box body, a plurality of protruding strip-shaped cooling fins are arranged on the outer wall of the box body, an oil seal is arranged between a motor shell and a speed reducer shell, and a half-shaft gear bearing seat is arranged between the motor shell and the speed reducer shell. The bearing seat is fixedly connected with a flange on the inner wall of the motor shell, a rotor shaft of the motor is a hollow shaft, the left end of the rotor shaft is supported in the front end cover through a bearing and is fixedly connected with a rotary transformer, the other end of the hollow shaft is fixedly connected with a first gear and is inserted into a half axle gear bearing seat, and the half axle gear bearing seat is provided with a gear mounting cavity; the first gear is installed in the gear installation cavity, a receding groove is formed in the half axle gear bearing seat wa