The current invention relates to cone clutch for continuously variable transmission, It specifically deals with cone clutches operated with a torque ramp, for generating the necessary clamping force, used in v-belt based continuously variable transmission.
Cone clutches are power transmission units working on the principles of friction drive. It consists of conical surfaces held together with a clamping force. The friction between the contacting surfaces allows the power transmission between them. Figure 1 shows a typical example of v-belt based continuously variable transmission that uses such a cone clutch. The friction between each of the half pulley and v-belt surface along with the clamping force P is used for power transfer between the pulley and the belt. The clamping force between the conical surfaces can be generated in a number of ways such as using compression or torsion spring, fly mass, torque ramps or a combination of these.
Torque ramp is used in cone clutch to sense the shaft torque and provide clamping force proportional to the torque. Torque ramp is a helical surface at an angle to the shaft axis, where the tangential force due to torque transfer generates a reaction force having axial component. The magnitude of the axial component is proportional to the angle and the shaft torque.
Figure 2 shows a typical cone clutch anangement that uses torque ramp to generate the clamping force for a v-belt continuously variable transmission. In such designs the torque ramp 1 is placed between the moveable half pulley 4 and the shaft 2 of the cone clutch C hence responding to half the shaft torque. The moveable half pulley 4 is also free to rotate on shaft 2 supported by any known means (say bushes). The fixed half pulley 5 is integrated to shaft 2, by any known means (say welding), so half the shaft torque flows directly between them. The v-belt member 6 is held between the fixed half pulley 5 and the moveable half pulley 4 with a clamping force F. The different ratios of torque transmission are achieved by varying the mean diameter for belt operation D. This is achieved by axially moving the moveable half pulley 4 with respect to the fixed half pulley 5. The torque transmission has to take place through an angular contact at torque ramp 1, for a given belt diameter D, in order to generate a proportional clamping force P. The axial motion requirement of the moveable half pulley 4 along with the angular contact requirement for torque transmission results in the angular rotation of the moveable half pulley 4 with respect to shaft 2 as it moves axially during ratio shift.
The major disadvantage of such a system is that the fixed half pulley 5 is an integral part of the shaft 2. This results in a relative rotational motion between the fixed half pulley 5 and the moveable half pulley 4 smearing the belt member 6 held between them with clamping force. This reduces the life of the belt member. In some of the designs the axial clamping force F is reduced in order to reduce this smearing of the belt member 6 and hence allowing belt slip along with loss of transmission efficiency.
To overcome the above said problem it is conceived to disconnect the shaft and fixed half pulley allowing free rotation of the fixed half pulley on shaft allowing axial location alone. This disconnection will avoid relative motion between the half pulleys and hence

the smearing of the belt member. This modification also calls for a different path for torque flow between the fixed half pulley and the shaft.
The present innovation was made in this situation so as to have a torque ramp for generating the necessary clamping force without smearing the belt and transmitting the complete shaft torque. Figure 3 and figure 4 shows an embodiment of the invention for the following explanation. In this design the axial position of the fixed half pulley 5a is arrested with respect to shaft 2a but it is free to rotate about the shaft 2a. The torque ramp la still connects the moveable half pulley 4a and the shaft 2a. The innovative part of the design is connecting the moveable half pulley 4a and fixed half pulley 5a with relative axial motion alone, removing the relative rotational motion using any known arrangement 4b such as splines or slots with roller followers. The belt member 6a is held between the moveable half pulley 4a and the fixed half pulley 5a at a diameter Da with a clamping force Fa. The ratio change takes place by axially moving the moveable half pulley 5b with respect to fixed half pulley 5a. As the moveable half pulley 4a moves axially, during ratio shift, it rotates relative to the shaft 2a due to torque ramp la. The fixed half pulley 5a also rotates along with the moveable half pulley 4a relative to the shaft 2a .The torque flow path between the fixed half pulley 5a and the shaft 2a is through the spline 4b and the torque ramp la.
This innovative solution allows the clamping force necessary for efficient torque transmission by the cone clutch with out smearing the belt member as the relative motion between the half pulleys is removed during ratio shift. Since the complete shaft torque flows through the torque ramp, this design gives double the response compared to the existing designs.

We Claim:
1. A cone clutch system for continuous variable transmission without smearing the belt of the said system, comprising a torque ramp for generating the necessary clamping force; a fixed half pulley mounted on a shaft, the torque ramp connecting a moveable half pulley and the said shaft; the belt being held between the said half pulleys at a diameter Da with clamping force Fa, characterized in that the movable half pulley is connected to the fixed half pulley with relative axial movement alone, the ratio change taking place by the axial movement of the moveable half pulley with respect to the fixed half pulley, during which movement, the movable half pulley rotates relative to the said shaft due to the torque ramp, the fixed halfpulley, during ratio change, also rotating with the movable halfpulley relative to the said shaft
2.A cone clutch system for continuous variable transmission substantiallyas herein described with reference to and as