Cone-pulley belt-type transmission

Claim 1

In an infinitely variable cone pulley transmission having driving and driven shafts, at least two cone pulley pairs each on a respective shaft, with one pulley of each pair being axially movable and rotatable relative to its associated shaft and having an axially projecting portion defining a rotating hydraulic cylinder, two pistons each mounted on a respective shaft to rotate as a unit therewith and inserted within the hydraulic cylinder of the one pulley on its associated shaft to define a hydraulic fluid chamber, a transmission element connected to circulate between the pulley pairs for transmitting power between the shafts, hydraulic fluid supply means including a source of hydraulic pressure fluid, fluid delivery passages communicating with the two hydraulic fluid chambers, a hydraulic fluid return passage communicating with a low pressure hydraulic fluid receiving region, a control slide valve connected between the source of hydraulic pressure fluid and the fluid delivery passages for controlling the hydraulic pressure in each chamber which determines the force with which the associated pulley pair bears against the transmission element, a transmission ratio setting member coupled to the slide valve for setting the transmission ratio between the shafts, a pressure control valve communicating with the fluid return passage and mounted on one of the shafts to rotate therewith and being adjustable in dependence on the torque between the shaft on which it is mounted and the one pulley of the pair on that shaft, and means including an axially extending bore in the one of the shafts for supplying the pressure control valve with hydraulic fluid at the pressure in the hydraulic fluid chamber of the cylinder associated with the driven shaft for causing the pressure control valve to control the pressure in that chamber in dependence on the set transmission ratio and the mechanical load on the transmission, the pressure control valve being composed of a member defining a pressure control cylinder communicating with the axially extending bore in the one of the shafts and with the fluid return passage, a valve body movable in the pressure control cylinder for varying the flow path defined by the flow control valve between the chamber of the cylinder associated with the driven shaft and the low pressure hydraulic fluid receiving region, a movably mounted intermediate member for moving the valve body, and means defining a V-shaped groove in the axially projecting portion defining the rotating hydraulic cylinder associated with the shaft on which the pressure control valve is mounted, the V-shaped groove extending parallel to the axis of that shaft and contacting the intermediate member for moving the valve body in response to rotation of the shaft on which the pressure control valve is mounted relative to the axially projecting portion defining the cylinder associated with that shaft, the improvement wherein said member defining said pressure control cylinder is mounted in said piston which is mounted on the same shaft as said pressure control valve and said V-shaped groove is disposed in an axially extending surface of its associated axially projecting portion.