Compliant overrunning clutch with centrifugal throw-out

An overrunning ratchet and pawl clutch mechanism comprising:

• a ratchet wheel having a plurality of angled teeth disposed about the perimeter thereof;
• a compliant, one-piece pawl wheel configured to rotate in a first engaging direction and in a second overrun direction, said pawl wheel comprising:
• a circular hub concentrically surrounding said ratchet wheel and having an inner surface;
• a plurality of elongate compliant biasing members having a proximal end and a distal end, said biasing members being integrally formed of the material of said hub and extending from said proximal end at the inner surface of said hub toward said distal end nearer the center of said hub;
• a plurality of clutch pawls integrally formed of the material of said hub at the distal end of each of said elongate compliant biasing members, each pawl being resiliently biased between the inner surface of said hub and the perimeter of said ratchet wheel by means of said elongate biasing members, each pawl having a tooth for engaging at least one tooth of said ratchet wheel when the pawl wheel rotates in said first engaging direction, and configured to slide over the teeth of said ratchet wheel when the pawl wheel rotates in said second overrun direction, said pawls being configured as pure compression members, to transmit the rotational force of the pawl wheel to the ratchet wheel solely via a compressive force therebetween, with no clutch output load imposed upon the compliant biasing member.

A micromechanical overrunning ratchet and pawl clutch mechanism formed upon a substrate, said mechanism having an overall diameter less than 2 millimeters and comprising:

• a rotatable ratchet wheel having a plurality of angled teeth disposed about the perimeter thereof, said ratchet wheel being configured to rotate in a first engaging direction and in a second overrun direction;
• a compliant pawl hub concentrically surrounding said ratchet wheel and being rotatable relative thereto, said pawl hub having an inner surface;
• a plurality of elongate compliant biasing members having a proximal end and a distal end, said biasing members being integrally formed of the material of said hub and extending from said proximal end at the inner surface of said hub toward said distal end nearer the center of said hub;
• a plurality of clutch pawls integrally formed of the material of said hub at the distal end of each of said elongate compliant biasing members, each pawl having a tooth for engaging at least one tooth of said ratchet wheel when it rotates in said first engaging direction, and configured not to engage the teeth of said ratchet wheel when it rotates in said second overrun direction, said pawls being resiliently biased against said ratchet wheel by means of said elongate biasing members;
• and
• wherein said elongate biasing members and said pawls are configured to compliantly allow the teeth of said pawls to substantially rotate away from the teeth of said ratchet wheel by means of centrifugal force when said bawl hub rotates in said overrun direction, whereby sliding contact between the pawls and the ratchet teeth is reduced.

An overrunning ratchet and pawl clutch mechanism comprising:

• a ratchet wheel having a plurality of angled teeth disposed about the perimeter thereof;
• a compliant, one-piece pawl wheel configured to rotate in a first engaging direction and in a second overrun direction, said pawl wheel comprising:
• a circular hub concentrically surrounding said ratchet wheel and having an inner surface;
• a plurality of elongate compliant biasing members having a proximal end and a distal end, said biasing members being integrally formed of the material of said hub and extending from said proximal end at the inner surface of said hub toward said distal end nearer the center of said hub;
• a plurality of clutch pawls integrally formed of the material of said hub at the distal end of each of said elongate compliant biasing members, each pawl being resiliently biased between the inner surface of said hub and the perimeter of said ratchet wheel by means of said elongate biasing members, each pawl having a tooth for engaging at least one tooth of said ratchet wheel when the pawl wheel rotates in said first engaging direction, and configured to slide over and substantially clear the teeth of said ratchet wheel when the pawl wheel rotates in said second overrun direction;
• and
• wherein said pawls are configured as pure tension members, to transmit the rotational force of the pawl wheel to the ratchet wheel solely via a tensile force through the pawl and the elongate compliant biasing members.