Rotary actuator and robot

1. A rotary actuator comprising:

a motor including a rotor and a stator; and

a rotation restricting mechanism which restricts rotation of the rotor that has stopped;

a case body in which the motor and the rotation restricting mechanism is accommodated, wherein

the rotation restricting mechanism includes:

a substantially annular rotation-side restricting member fixed to the rotor;

a fixed-side restricting member which engages with the rotation-side restricting member to restrict movement of the rotation-side restricting member in a circumferential direction of the rotor; and

a drive mechanism which moves the fixed-side restricting member in an axial direction of the rotor,

a plurality of protrusions which protrude inward or outward in a radial direction of the rotor are formed on the rotation-side restricting member at regular intervals in the circumferential direction,

a restricting portion which enters between the protrusions in the circumferential direction to restrict movement of the rotation-side restricting member in the circumferential direction is formed in the fixed-side restricting member, and

the drive mechanism moves the fixed-side restricting member between a restriction position at which the restricting portion is disposed between the protrusions in the circumferential direction and a restriction release position at which the restricting portion is removed from between the protrusions in the circumferential direction,

wherein the drive mechanism comprises:

a biasing member which biases the fixed-side restricting member toward one side in the axial direction; and

a solenoid which moves the fixed-side restricting member to the other side in the axial direction,

wherein the biasing member biases the fixed-side restricting member toward the restriction position,

the solenoid moves the fixed-side restricting member at the restriction position to the restriction release position,

the fixed-side restricting member is fixed to one end portion of a plunger of the solenoid,

a through hole in which the other end portion of the plunger or a pin fixed to the other end portion of the plunger is disposed is formed in the case body,

the other end portion of the plunger or a portion of the pin protrudes to the outside of the case body when the fixed-side restricting member is at the restriction position, and

the fixed-side restricting member at the restriction position moves to the restriction release position when the other end portion of the plunger or a portion of the pin protruding to the outside of the case body is pushed toward the inside of the case body.

2. The rotary actuator according to claim 1 , wherein

an outer shape of the restricting portion is circular when viewed from the axial direction, and

a diameter of the restricting portion when viewed from the axial direction is substantially half of a distance between the protrusions in the circumferential direction.

3. The rotary actuator according to claim 1 , wherein the protrusions protrude outward in the radial direction.

4. A robot comprising a joint portion constituted by the rotary actuator according to claim 1 .