Fast reacting thermal clutch

Abstract

A thermal clutch assembly is comprised of a radially inner rotatable member, a radially outer rotatable member a pair of axially spaced apart ring structures, and a thin tension web. The ring structures are both affixed to and rotate with one of the rotatable members and each has at least one substantially axial surface which may contact substantially axial surfaces of the other rotatable member. The tension web has high tensile strength, a high surface area to volume ratio, a thermally efficient flow arrangement to the surrounding medium, and high thermal conductivity. The tension web is secured to each of the two ring structures and substantially spans the space between the substantially axial surfaces of the ring structures, the web having a significantly higher thermal coefficient of expansion than the material between the substantially axial surfaces of the other rotatable member. In this manner, the web is in tension at temperatures of the surrounding medium below a predetermined temperature thereby causing the substantially axial surfaces of the ring structures to engage the substantially axial surfaces of the other rotatable member for coupling the two rotatable members for rotating together, and is not in tension at temperatures of the surrounding medium at or above the predetermined temperature thereby causing the substantially axial surfaces of the ring structures to disengage from the substantially axial surfaces of the other rotating structure for de-coupling the two rotatable members so they do not rotate together.