This invention relates to a cone clutch operated with a rorque ramp, for generating the necessary clamping force, used in a v-belt based continuously variable transmission system.
In the accompanying drawings,
Fig. 1 illustrates Figure 1 shows atypical example of v-belt based continuously variable transmission that uses such a cone clutch
Figure 2 illustrates a typical cone clutch arrangement that uses torque ramp to generate the clamping force for a v-belt continuously variable transmission
Figure 3 and Figure 4 illustrate an embodiment of the invention by way of example and not by way of limitation.
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 has 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 arrangement 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 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 F. 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 centrifugal clutch 7 is permanently connected to shaft 2 using any known means of connection like, D-slots, threaded arrangement, welding or a combination of these for torque transmission between 7 and 2.
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 distorting the belt 6 held between them with clamping force. This reduces the life of the belt. In some of the designs the axial clamping force F is reduced in order to reduce this distortion of the belt 6 and hence allowing belt slip along with loss of transmission efficiency.
To overcome the above said problem it is proposed to disconnect the shaft and fixed half pulley allowing free rotation of the fixed half pulley on shaft permitting axial

^ocation alone. This disconnection will avoid relative motion between the half pulleys and hence the distortion of the belt. This also calls for a different path for torque flow between the fixed half pulley and the shaft.
The present invention therefore proposes to have a torque ramp for generating the necessary clamping force without distorting the belt and transmitting the complete shaft torque to the shaft with centrifugal clutch
Figure 3 and Figure 4 illustrate an embodiment of the invention. In this design the axial position of the fixed half pulley 5a is arrested with respect to shaft 2 but it is free to rotate about it. The torque ramp 1 a still connects the moveable half pulley 4a and the shaft 2a through boss 3 a. The important aspect of the construction is connecting the moveable half pulley 4a and fixed half pulley 5 a with relative axial motion alone, removing the relative rotational motion using any known arrangement 3b such as splines or slots with roller followers. The belt 6a is held between the moveable half pulley 4a and the fixed half pulley 5 a at a diameter Da with a clamping force Fa. The ratio change takes place by axially moving the moveable half pulley 4a 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 due to slot 5b .The torque flow path between the moveable half pulley 4a and the shaft 2a is through and pin 3d, roller 3b and torque ramp la. The torque flow path between the fixed half pulley 5a and the shaft 2a is through the slot 5b, roller 3c, roller 3b and torque ramp la.
This invention thus allows the clamping force necessary for efficient torque transmission by the cone clutch without distorting the belt as the relative rotational motion between the half pulleys is removed during ratio shift. In other words this invention allows linear motion of the moveable pulley with respect to fixed pulley without axial increase in assembly dimensions using minimum space diametrically. Also the complete shaft torque flows through the torque ramp, giving a higher response in axial clamping.
It will be appreciated that various other embodiments of this invention are possible without departing from the scope and ambit of this invention

We Claim:
1 A cone clutch operated with a torque ramp, for generating the necessary clamping force, used in a v-belt based continuously variable transmission system, comprising a fixed half pulley, the axial position of which is arrested with respect to its shaft, said pulley however being free to rotate about the said shaft; a moveable half pulley and a shaft connected by a torque ramp through a boss, characterised in that the moveable half pulley and fixed half pulley are connected by relative axial motion alone, eliminating relative rotational motion, the belt being held between the moveable half pulley and the fixed half pulley, the ratio change taking place by axially moving the moveable half pulley with respect to fixed half pulley, whereby as the moveable half pulley moves axially, during ratio shift, it rotates relative to the shaft due to torque ramp, the fixed half pulley also rotating along with the moveable half pulley relative to the shaft due to a slot, to eliminate the relative rotational motion between the half pulleys during ratio shift
2. A cone clutch operated with a torque ramp, for generating the necessary clamping force, used in a v-belt based continuously variable transmission system

substantially as herein described and illustrated with reference to he accompanying drawings.