Actuator with clutch mechanism

An actuator having a clutch mechanism, the clutch mechanism being provided between a driving rotor, which is driven by a motor, and a driven rotor, wherein the clutch mechanism selects from a state for transmitting rotational force of the driving rotor to the driven rotor and a state for discontinuing the transmission of rotational force generated from the driven rotor to the driving rotor, wherein the clutch mechanism comprises:

• a plurality of rolling bodies located between the driving rotor and the driven rotor;
• a holder for holding the rolling bodies, wherein the holder permits the rolling bodies to roll, wherein the holder supports the rolling bodies such that the rolling bodies are switched between a transmitting position and a disconnecting position, wherein, when held at the transmitting position, the rolling bodies are engaged with both of the driving rotor and the driven rotor so that rotational force of the driving rotor is transmitted to the driven rotor, wherein, when held at the disconnecting position, the rolling bodies are disengaged from the driving rotor so that the transmission of rotational force from the driven rotor to the driving rotor is discontinued, and wherein, when external rotational force is applied to the driven rotor, the holder sets the rolling bodies to the disconnecting position;
• a housing wherein the driving motor and the driven rotor are coaxially arranged in the housing around a rotation axis;
• and
• wherein the holder includes a cylindrical portion and an annular portion, wherein the cylindrical portion is located between the driving rotor and the driven rotor, and the annular portion is formed in the circumference of the cylindrical portion, wherein the rolling bodies are supported by the cylindrical portion, and are arranged at equal angular intervals, wherein the holder is supported by the housing with the annular portion, wherein the annular portion is located radially outward of the rolling bodies and wherein the annular portion and the rolling bodies are located on an imaginary plane perpendicular to an axis of the driven rotor.

A clutch mechanism for transmitting rotational force of a driving rotor to a driven rotor, which is coaxial with the driving rotor, wherein the clutch mechanism permits the driven rotor to rotate without transmitting rotational force generated from the driven rotor to the driving rotor, the clutch mechanism comprising:

• a substantially cylindrical collar, wherein the collar rotates integrally with the driven rotor;
• a clutch shaft, which is located inside of the collar and rotates integrally with the driving rotor, wherein a cut-off surface is formed in the circumference of the clutch shaft such that the distance between the cut-off surface and the inner surface of the collar varies;
• a rolling body located between the inner surface of the collar and the cut-off surface, wherein the diameter of the rolling body is loss than the distance between the inner surface of the collar and a center section of the cut-off surface and is longer than the distance between the inner surface of the collar and a side section of the cut-off surface;
• a rotation limiting member, which engages with the rolling body in a rotation direction about the axis of the driving rotor and rotates integrally with the rolling body, wherein the rotation limiting member has an engaged portion located radially outside of the collar, wherein the rotation limiting member is located radially outside of the rolling body, and wherein the rotation limiting member and the rolling body are located on an imaginary plane perpendicular to an axis of the driving rotor;
• and
• a friction creating portion, which holds the engaged portion with a holding force of a predetermined value, and wherein the friction creating portion permits the engaged portion to be rotated by a rotational force that is greater than the predetermined value.