Transmission assembly, speed reducer and industrial robot

The utility model discloses a transmission assembly, a speed reducer and an industrial robot. The cycloidal gear is provided with a cycloidal gear bearing hole. The planet carrier is provided with a planet carrier bearing hole. And the first bearing is mounted in a cycloidal gear bearing hole. The second bearing is installed in a planet carrier bearing hole. The eccentric shaft comprises a shaft body and an eccentric part. The eccentric part is connected with the shaft. The axis of the eccentric part is parallel to the axis of the shaft body. The eccentric part is connected with the first bearing so as to penetrate through the cycloidal gear bearing hole. The shaft body is connected with the second bearing to penetrate through the planet carrier bearing hole. The eccentric portion includes a first contact surface. The shaft body comprises a second contact surface. And the hole wall of the cycloidal gear bearing hole comprises a third contact surface. And the hole wall of the planet carrier bearing hole comprises a fourth contact surface. And the first contact surface is in contact with the third contact surface through a first bearing. And the second contact surface is in contact with the fourth contact surface through a second bearing. And at least one of the first contact surface, the second contact surface, the third contact surface and the fourth contact surface is a non-cylindrical surface with a non-circular cross section.