A Ratio Disc CVT Transmission

A new CVT and the construction of prototypes are to be described. Objectives include:

• Highest efficiency
• Ease of ratio change
• Large engine power capability
• Rapid response to torque changes
• Simple shapes for low manufacturing costs

A single disc is arranged transversely between two traction gearing planetaries. The high efficiency of bodies in pure rolling (i.e. without spin) is used to effect clamping forces without the need for auxiliary power. Very little power is used to effect ratio changes because the power being transmitted through the transmission is used to effect the ratio changes in response to a slight change in the lateral position of the disc. A trade-off exists between size and efficiency. Large power capability is possible because there are no members being subjected to centrifugal forces as in belt drives, and because contact conditions involve very little spin losses with their attendant heat limitations as encountered in toroidal types of CVTs.

Figure 1