Abstract: Provided is a compact spring return actuator. The actuator includes a driving shaft configured to be rotated by receiving a driving force from a motor, a driven shaft configured to open and close a valve by being rotated by the driving shaft, a deceleration means configured to decelerate a rotational force that is transmitted to the driven shaft, the deceleration means including a differential planetary gear decelerator provided at the driving shaft, and includes an emergency return means provided with an elastic body and an actuation shaft which is configured to convert an elastic force of the elastic body to a rotational force and to transmit the rotational force and which is engaged with the differential planetary gear decelerator, thereby being configured to rotationally return the valve when power is blocked.

Abstract: Provided is a compact spring return actuator. The actuator includes a driving shaft configured to be rotated by receiving a driving force from a motor, a driven shaft configured to open and close a valve by being rotated by the driving shaft, a deceleration means configured to decelerate a rotational force that is transmitted to the driven shaft, the deceleration means including a differential planetary gear decelerator provided at the driving shaft, and includes an emergency return means provided with an elastic body and an actuation shaft which is configured to convert an elastic force of the elastic body to a rotational force and to transmit the rotational force and which is engaged with the differential planetary gear decelerator, thereby being configured to rotationally return the valve when power is blocked.