Abstract: This speed reducer with an electric motor has: a hollow shaft; a casing fixed to the hollow shaft; a fixed part that is relatively stationary with respect to the casing; an electric motor; a speed reduction mechanism; an output part; and a torque sensor that is connected to the casing and the fixed part. The torque sensor has an elastically deformable strain body that has an annular outer ring and an annular inner ring and a plurality of strain sensors. The outer ring and the inner ring are respectively located at an end portion on the radial outside and the radial inside of the torque sensor and is connected to one of the casing and the fixed part. Each of the plurality of strain sensors is at least partially located in a radial direction between the outer ring and the inner ring.

Abstract: A power unit comprises: a wave gear speed reducer, a rotary shaft extending in the axial direction; a rotor unit that rotates integrally with the rotary shaft; a stator unit disposed facing the rotor unit; and a motor casing to which the stator unit is secured. The motor casing has a second cover that covers the rotor unit and the stator unit from the other side in the axial direction. The rotary shaft extends toward the other side in the axial direction, penetrates the second cover, and is connected to a cam. The second cover has a support part that extends toward the other side in the axial direction, supports the rotary shaft in a rotatable manner, and is positioned in a flexible cylindrical part of an external gear.

Abstract: In a speed reducing unit with an electric motor, a speed reduction mechanism has: an elliptical cam that rotates together with a rotating part; a flexible external gear that deforms according to the rotation of the elliptical cam; a flexible bearing that is located between the elliptical cam and the flexible external gear; and a movable internal gear that rotates together with an output part. The flexible external gear and the movable internal gear are engaged with each other. The electric motor has: a rotor holder that is part of the rotating part and that rotates together with the elliptical cam; a rotor magnet that is fixed to the rotor holder; and a stator that is fixed to a casing. The rotor holder has a rotor-holder lid part, and the positions of the rotor-holder lid part and the flexible bearing in the axial direction at least partially overlap.

Abstract: This speed reducer with an electric motor has: a hollow shaft; a casing fixed to the hollow shaft; a fixed part that is relatively stationary with respect to the casing; an electric motor; a speed reduction mechanism; an output part; and a torque sensor that is connected to the casing and the fixed part. The torque sensor has an elastically deformable strain body that has an annular outer ring and an annular inner ring and a plurality of strain sensors. The outer ring and the inner ring are respectively located at an end portion on the radial outside and the radial inside of the torque sensor and is connected to one of the casing and the fixed part. Each of the plurality of strain sensors is at least partially located in a radial direction between the outer ring and the inner ring.

Abstract: A motor unit for a wave gear speed reducer is equipped with: a rotary shaft extending in the axial direction; a rotor unit that rotates integrally with the rotary shaft; a stator unit disposed facing the rotor unit; and a motor casing to which the stator unit is secured. The motor casing has a second cover that covers the rotor unit and the stator unit from the other side in the axial direction. The rotary shaft extends toward the other side in the axial direction, penetrates the second cover, and is connected to a cam. The second cover has a support part that extends toward the other side in the axial direction, supports the rotary shaft in a rotatable manner, and is positioned on the inside of an external gear when a wave gear speed reducer is attached to the motor casing.

Abstract: In a speed reducing unit with an electric motor, a speed reduction mechanism has: an elliptical cam that rotates together with a rotating part; a flexible external gear that deforms according to the rotation of the elliptical cam; a flexible bearing that is located between the elliptical cam and the flexible external gear; and a movable internal gear that rotates together with an output part. The flexible external gear and the movable internal gear are engaged with each other. The electric motor has: a rotor holder that is part of the rotating part and that rotates together with the elliptical cam; a rotor magnet that is fixed to the rotor holder; and a stator that is fixed to a casing. The rotor holder has a rotor-holder lid part, and the positions of the rotor-holder lid part and the flexible bearing in the axial direction at least partially overlap.