Continuously variable transmission driven element

Abstract

The invention is a secondary, or driven, element suitable for use as one element of a three-element continuously variable transmission comprising a primary drive sheave, a V-belt, and the secondary drive sheave. Both sheaves have variable pitch diameters. The pitch diameter of the primary split sheave increases with increasing rotation rate, and the pitch diameter of the secondary split sheave increases as the torque applied to the load increases. The moveable portion of the driven sheave is fitted with a cam in the form of a helix in a hollow cylinder. A roller-type cam follower is mounted perpendicular to the sheave rotational axis on a stub shaft, or spider, that extends radially from the post, an axial extension of the fixed sheave portion. A spring biases the driven sheave portions toward maximum pitch diameter. Increased torque tends to rotate the moveable sheave portion with respect to the shaft and fixed sheave. As the moveable sheave rotates, the cam displaces the moveable sheave toward the fixed sheave. When the torque requirements are lessened, the primary sheave may rotate faster causing the fixed-length V-belt to force the driven sheave faces apart. The roller-spider, cam follower and helical cam assembly act in concert with the spring to provide additional torque when the demand is sensed. This new driven element responds to changing power requirements and loads more quickly and precisely than do previously known CVT secondary elements.