Transmisiones Tsp, S. A., De, C.v.

Transmission Technologies Corporation

John M Loeffler

Charles B Lohr

Gordon M McIndoe

An apparatus and method for operating a continuously variable transmission (CVT), such as a toroidal drive type transmission, is disclosed. The CVT is selectively operated in either a torque control strategy and a ratio control strategy, depending upon the operating conditions of the vehicle. Thus, the CVT is operated in such a manner as to benefit from the advantageous aspects of both the torque and ratio control strategies, while avoiding the disadvantageous aspects of both strategies. The transition from the torque control strategy to the ratio control strategy (and vice versa) can be accomplished by simultaneously calculating the control pressures that would result from operation in both the torque and ratio control strategies, and further assigning a weighted value to each of such calculated control pressures based upon the current operating conditions. The summation of such weighted values provides a composite control signal that facilitates a smooth transition between the two control strategies. The transition from the torque control strategy to the ratio control strategy preferably occurs before a mode shift is effected. Negative feedback is provided in response to ratio changes effected by the control signals to increase stability and to compensate for sensitivity differences at different ratio angles, loading, speeds, and temperatures.

Dual strategy control for a toroidal drive type continuously variable transmission

A shift rail and fork assembly for a transmission includes a shift channel having a pair of side pieces that are connected together by cross pieces. A plurality of shift rails are supported on the shift channel for relative sliding movement. A corresponding plurality of shift forks are supported on the shift channel for relative sliding movement. The shift rails are connected to the shift forks for concurrent longitudinal movement. A cross slide is supported on the shift channel for relative lateral movement. The cross slide including a depending tang that selectively cooperates with corresponding slots formed each of the shift rail for concurrent movement. The cross slide can be moved laterally such that the selector tangs engage any desired one of the shift rails. An interlock bracket is also supported for lateral movement relative to the shift channel, but is prevented from longitudinal movement. To initiate a shifting operation, a shift lever is first moved in the lateral direction to select one of the shift rails, causing lateral movement of both the cross slide and the interlock bracket. The lateral movement of the cross slide causes selector tangs provided thereon to become laterally aligned with a slot formed in a selected one of the shift rails. At the same time, the lateral movement of the interlock bracket causes depending arm portions provided thereon to become laterally aligned with slots formed in all of the other non-selected shift rails. Then, the shift lever is subsequently moved in a longitudinal direction, causing the cross slide, the selected one of the shift rails, and the shift channel to be moved longitudinally therewith. The interlock bracket prevents the non-selected shift rails from moving longitudinally.

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Whitehouse, OH, United States of America

John M Loeffler