ASSEMBLIES AND METHODS FOR CLAMPING FORCE GENERATION
Mechanisms and methods for clamping force generation are disclosed. In one embodiment, a clamping force generator system includes a permanent magnet bearing coupled to a traction ring and to a torque coupling. The traction ring can be provided with an electromagnetic bearing rotor and the torque coupling can be provided with an electromagnetic bearing stator. In some embodiments, a mechanical load cam, a permanent magnet bearing, and an electromagnetic bearing cooperate to generate a clamping force between the traction rings, the power rollers, and the idler. In other embodiments, a series of permanent magnet bearings and a mechanical bearing configured to produce a clamping force. In one embodiment an electromagnetic bearing is coupled to a control system and produces a specified clamping force that is associated with a torque transmitted in the transmission during operation. In some embodiments, a mechanical load cam produces a clamping force proportional to torque, while a permanent magnet bearing provides a minimum clamping force.
1 . A method of controlling an axial force in a continuously variable transmission (CVT) having a plurality of spherical power rollers in contact with a first traction ring, a second traction ring, and a support member, the method comprising the steps of:
receiving, by a control system, a signal associated with an operating condition of the CVT;
determining a clamping force based on the received signal; and
configuring an axial force generator to provide the determined clamping force, the axial force generator comprising a permanent magnet bearing and an electromagnetic bearing for receiving a rotational power.
2 . The method of claim 1 , wherein configuring the axial force generator comprises optimizing the operating efficiency of the CVT.
3 . The method of claim 1 , wherein the clamping force is a constant clamping force.
4 . The method of claim 1 , wherein the clamping force is a minimum clamping force.
5 . The method of claim 1 , wherein the signal is indicative of one or more of torque, temperature, and component speed.
6 . The method of claim 1 , wherein determining the clamping force based on the received signal comprises using an algorithm to determine an optimum clamping force.
7 . The method of claim 1 , wherein configuring the axial force generator to provide the determined clamping force is performed dynamically.
8 . The method of claim 1 , further comprising configuring the axial force generator to provide a predetermined clamping force.
9 . A system for controlling an axial force in a continuously variable transmission (CVT) having a plurality of spherical power rollers in contact with a first traction ring, a second traction ring, and a support member, the system comprising:
a controller configured for
receiving a signal associated with an operating condition of the CVT,
determining a clamping force based on the received signal, and
communicating an indication of the determined clamping force to an axial force generator comprising a permanent magnet bearing and an electromagnetic bearing for receiving a rotational power, wherein the axial force generator is configured to provide the determined clamping force.
10 . The system of claim 9 , wherein the axial force generator is configured to optimize the operating efficiency of the CVT.
11 . The system of claim 9 , wherein the clamping force is a constant clamping force.
12 . The system of claim 9 , wherein the clamping force is a minimum clamping force.
13 . The system of claim 9 , wherein the signal is indicative of one or more of torque, temperature, and component speed.
14 . The system of claim 9 , wherein the controller is configured to determine the clamping force based on the received signal using an algorithm to determine an optimum clamping force.
15 . The system of claim 9 , wherein the axial force generator is configured to provide the determined clamping force dynamically.
16 . The system of claim 9 , wherein the axial force generator is further configured to provide a predetermined clamping force.