Continuously variable transmission system with engine braking

A continuously variable transmission system comprising:

• a rotatable input shaft connectable to an engine of a vehicle;
• a rotatable drive clutch connected to the input shaft, the drive clutch having
• a laterally stationary sheave with an inner belt-engaging surface,
• a laterally movable sheave with an inner belt-engaging surface,
• biasing means for normally biasing the movable sheave away from the stationary sheave and for selectively moving the movable sheave toward the stationary sheave in response to rotation of the drive clutch,
• a roller clutch carried on the input shaft, and
• a generally cylindrical belt-engaging surface connected to the roller clutch;
• a rotatable output shaft;
• a rotatable split sheave driven clutch connected to the output shaft;
• and
• an endless flexible drive belt disposed about the drive and driven clutches, the belt having an inner drive surface engageable with the generally cylindrical belt-engaging surface and a pair of side drive surfaces engageable between the inner belt-engaging surfaces of the sheaves, the size of the drive belt being selected so that when the engine is at an idle speed the inner surface of the belt firmly engages the generally cylindrical belt-engaging surface connected to the roller clutch;
• the roller clutch being configured and arranged to permit the cylindrical belt-engaging surface to remain substantially stationary when the input shaft is rotating, thereby permitting the belt and driven clutch to remain substantially stationary when the engine is at an idle speed.

A continuously variable transmission system comprising:

• an input shaft connectable to an engine of a vehicle, the input shaft being rotatable in a driving direction;
• a rotatable drive clutch connected to the input shaft for rotation therewith in the driving direction, the drive clutch having
• a laterally stationary sheave with an inner belt-engaging surface,
• a laterally movable sheave with an inner belt-engaging surface, and
• biasing means for normally biasing the movable sheave away from the stationary sheave and for selectively moving the movable sheave toward the stationary sheave in response to rotation of the drive clutch;
• a rotatable output shaft connectable to a drive axle of the vehicle;
• a rotatable driven clutch connected to the output shaft, the driven clutch having
• a laterally stationary sheave with an inner belt-engaging surface, the stationary sheave being mounted to a roller clutch, which in turn is mounted to the output shaft, the roller clutch providing positive rotational engagement of the stationary sheave against the output shaft when the stationary sheave is rotated in the direction of driving rotation of the drive clutch and the input shaft, the roller clutch permitting the stationary sheave to rotate in the opposite direction with respect to the output shaft;
• a laterally movable sheave with an inner belt-engaging surface, the movable sheave having one or more cam followers and being rotatable with respect to the output shaft and the stationary sheave;
• a generally cylindrical cam secured to the output shaft, the cam having one or more inclined ramps for engagement with the cam followers, the ramps functioning to urge the cam followers and therefore the movable sheave toward the stationary sheave in response to torque acting between the movable sheave and the cam;
• and
• means for normally biasing the movable sheave toward the stationary sheave;
• and
• an endless flexible drive belt disposed about the drive and driven clutches, the belt having an inner drive surface and a pair of side drive surfaces.

A continuously variable transmission system comprising:

• an input shaft connectable to an engine of a vehicle, the input shaft being rotatable in a driving direction;
• a rotatable split sheave drive clutch connected to the input shaft for rotation therewith in the driving direction;
• a rotatable output shaft;
• a rotatable split sheave driven clutch connected to the output shaft, the driven clutch having
• a laterally stationary sheave mounted to a one-way clutch which in turn is mounted to the input shaft, the one way clutch providing positive rotational engagement of the stationary sheave against the output shaft when the stationary sheave is rotated in the direction of driving rotation of the drive clutch and the input shaft, the one-way clutch permitting the stationary sheave to rotate in the opposite direction with respect to the output shaft;
• a laterally movable sheave having one or more cam followers and being rotatable with respect to the output shaft;
• a generally cylindrical cam secured to the output shaft, the cam having one or more inclined ramps against which the cam followers may be engaged, the ramps functioning to urge the cam followers and therefore the movable sheave toward the stationary sheave in response to torque acting between the movable sheave and the cam;
• and
• means for normally biasing the movable sheave toward the stationary sheave;
• and
• an endless flexible drive belt disposed about the drive and driven clutches.

A continuously variable transmission system comprising:

• a rotatable input shaft connectable to an engine of a vehicle;
• a rotatable split sheave drive clutch, the drive clutch including at least one belt-engaging surface;
• a roller clutch disposed between the input shaft and the belt-engaging surface of the drive clutch;
• a rotatable output shaft;
• a rotatable split sheave driven clutch connected to the output shaft;
• and
• an endless flexible drive belt disposed about the drive and driven clutches, the belt having at least one drive surface engageable with the belt-engaging surface of the drive clutch, the size of the drive belt and the configuration of the belt-engaging surface of the drive clutch being selected so that when the engine is at an idle speed the belt firmly engages the belt-engaging surface of the drive clutch;
• the roller clutch being configured and arranged to permit the belt-engaging surface of the drive clutch to remain substantially stationary when the input shaft is rotating, thereby permitting the belt and driven clutch to remain substantially stationary when the engine is at an idle speed, the roller clutch being further configured and arranged to firmly engage the drive clutch's drive surface with the input shaft when the driven clutch attempts to drive the belt faster than the speed at which the drive clutch and input shaft are rotating, thereby permitting the driven clutch to backdrive the input shaft and engine to provide engine braking to the vehicle.