Centrifugal clutch with one piece rotor

Claim 1

A centrifugal clutch comprising a clutch drum rotatable about an axis and having an inner surface of selected radius and a one piece rotor of resilient material having: a. a hub central portion rotatable about an axis concentric with the axis of said drum b. means for rotationally driving said hub portion c. two like weight portions on diametrically opposite sides of said hub portion and d. two like curved spring portions connecting diametrically opposite parts of said hub portion respectively with said weight portions e. the dimension of said hub portion measured between points of junction with said spring portions being of the order of 50 to 60 percent the diameter of said drum f. said weight portions having radially outer surfaces engageable with said inner surface of the drum and of a radius equal to the radius of the inner surface of the drum, said outer surfaces being disengaged from the inner surface of the drum and being eccentric of the axis of said drum when the rotor is in relaxed condition and so positioned that upon deflection into contact with said drum at a predetermined rotational speed said outer surfaces are concentric with said drum g. the ratio of the length of each of said spring portions measured along its radially inner side to the radius of the rotor being of the order of 0.8 to 1.0 h. said spring portions having first portions extending approximately radially from said hub portion, second portions extending circumferentially rearwardly from said weight portions, said second portions being approximately concentric with the drum axis and spaced radially inward from the inner surface of the drum, and smoothly curved third portions connecting said first and second portions i. the transverse width of said spring portions in the plane of rotation of the rotor being of such value at continuously successive points along the lengths of said spring portions as to provide substantially equal fiber stress in the radially innermost surfaces of said spring portions throughout substantially their entire lengths when said spring portions flex under the action of centrifugal force on said weight portions to bring them into engagement with the inner surface of the drum and are subjected to driving force transmitted through said spring portions from said hub to said weight portions and thence to the drums, said fiber stress being lower than the fatigue stress and endurance level of the material of the spring portions.