Patent ID: 7780557

Claim:
Continuously variable transmission for motor vehicles, comprising: an endless tensile means ( 2 ); a continuous array of transverse elements ( 3 ), said tensile means ( 2 ) and said transverse elements ( 3 ) together forming a transmission belt ( 1 ); and a set pulleys ( 4 , 5 ), each pulley mounted on a respective central pulley shaft ( 14 ), each pulley ( 4 , 5 ) having a mechanical stiffness and comprising a fixed disc ( 15 ) axially fixed with respect to said pulley shaft ( 14 ) and a movable disc ( 16 ) axially movable, under influence of a pressure exerted on said movable disc, for clamping said belt ( 1 ) between said discs ( 15 , 16 ), the exerted pressure providing a clamping force exerted on said belt ( 1 ) by said discs ( 15 , 16 ) and comprising an axial force Fax exerted on said movable disc ( 16 ), each disc having a belt contact surface ( 29 ), each transverse element ( 3 ) having lateral pulley contact surfaces ( 6 ) for contacting said belt contact surface ( 29 ) of each of said discs ( 15 , 16 ) and being provided slideably on said tensile means ( 2 ) of said belt ( 1 ), said belt contacting surfaces ( 29 ) mutually being oriented in a disposition with radially outward increasing mutual distance such that a cone angle λ is formed between each said belt contacting surface ( 29 ) and an imaginary radial line through said pulley shaft ( 14 ), said cone angle λ defining the angle under which said contact faces ( 29 ) and said transverse elements ( 3 ) mutually contact at each radial position of said belt ( 1 ) with respect to an axis of rotation of said pulley ( 4 , 5 ), wherein a stiffness related feature of each said pulley ( 4 , 5 ), when expressed as a parameter Sag that indicates an amount of radial displacement of said belt ( 1 ) between said discs ( 15 , 16 ) occurring in response to imposing a maximum amount of said axial force Fax during operation of said transmission, said displacement being measured relative to an initial radial position of said belt ( 1 ) in an unloaded state of the transmission, has a value in the range between 0.5 mm and 1.2 mm.