Abstract: Methods and devices for tailoring the functional relationship between the shift ratio of a CVT and the radial force (FR) into the cam surfaces of a CVT's helix. Such tailoring may effect downshifting, and the separation of the design of the upshift function from the design of the backshift function. Such tailoring may be effected by schemes that include the use of a helix with other than a constant distance from the rotational axis to the touch point (touch-point radius), a touch-point radius that is a monotonic function of the shift ratio, or a touch-point radius that is a meandering function of the shift ratio.

Abstract: Methods and devices for tailoring the functional relationship between the shift ratio of a CVT and the radial force (FR) into the cam surfaces of a CVT's helix. Such tailoring may effect downshifting, and the separation of the design of the upshift function from the design of the backshift function. Such tailoring may be effected by schemes that include the use of a helix with other than a constant distance from the rotational axis to the touch point (touch-point radius), a touch-point radius that is a monotonic function of the shift ratio, or a touch-point radius that is a meandering function of the shift ratio.

Abstract: Continuously variable speed drives (CVT) have improved performance over all shift ratios using an improved flyweight (camweight) that enhances power transfer for higher shift ratios (slower vehicle speeds) without compromising efficiency or performance at smaller shift ratios. Prior art CVTs characteristically have some belt slippage, and attendant power waste and excess wear, when operating with higher shift ratios. The prior art deficiency is due to a tendency of the prior art flyweights not to cause sufficient side forces (axial forces) on the belt at higher shift ratios. The present invention preferably supplements conventional flyweights with a massive shoulder that is a supplemental mass concentration placed near the flyweight's center of rotation, and at an obtuse angle from the center-of-mass (COM) of a conventional flyweight, such that the resultant centrifugal forces effect a desirable axial force. Embodiments are disclosed that allow adjusting the degree of improvement.