Abstract: 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.

Abstract: An apparatus for controlling the rate of engagement of a clutch in response to an indication provided by the driver, such as the depression of an accelerator pedal of the vehicle. The apparatus includes an electronic controller which initially determines a start rate as the minimum duty cycle which is required to modulate an engage valve in order to cause movement of a release bearing of the clutch in the engagement direction. The start rate is determined by initially moving the release bearing to the disengaged position. Then, the engage valve is modulated incrementally modulated until the release bearing begins moving in the engaged direction from the disengaged position. When a predetermined amount of such movement has been detected, the electronic controller sets the start rate as the current duty cycle of the engage valve.

Abstract: An apparatus and method for controlling the rate of engagement of a clutch in response to an indication provided by the driver, such as the depression of an accelerator pedal of the vehicle. The apparatus includes an electronic controller which initially determines a start rate as the minimum duty cycle which is required to modulate an engage valve in order to cause movement of a release bearing of the clutch in the engagement direction. Following the receipt of a signal from the operator of the vehicle to initiate the engagement of the clutch, the electronic controller calculates an initial transition rate of movement of the release bearing from a disengaged position to a transition point. The transition rate is determined as a function of the start rate and a position error signal. The position error signal can be calculated as the difference between the actual position of the release bearing and the transition point.

Abstract: An apparatus and method for controlling the operation of a clutch in a partially or fully automated mechanical transmission which is responsive to the actual load on the vehicle engine for varying the engagement rate of release bearing during re-engagement of the clutch. The apparatus includes an electronic controller which initially sets a desired speed for the vehicle engine during the shifting process, determines a rate of engagement movement of a release bearing of the clutch, and actuates appropriate valves to initiate the gradual engagement of the clutch. The electronic controller sets a first lower engine speed threshold and a second lower engine speed threshold. In a first embodiment, the magnitude of the first lower engine speed threshold varies with the actual load on the engine. If the actual speed of the engine remains above both the first lower engine speed threshold and the second lower engine speed threshold, the engagement process is continued without interruption.

Abstract: An apparatus and method for controlling the engagement rate of a clutch in a partially or fully automated mechanical transmission is responsive to certain calculations derived from the rotational speeds of the input member and the output member of the clutch. The apparatus includes an electronic controller which initially sets a desired speed for the vehicle engine during the shifting process, determines a rate of engagement movement of a release bearing of the clutch, and actuates appropriate valves to initiate the gradual engagement of the clutch. The electronic controller compares the actual speed of the engine with a first value. If the actual speed of the engine is greater than or equal to the first value, the electronic controller then compares the rotational speeds of the input and output shafts of the clutch in order to determine if the difference therebetween is less than a second value. In a first embodiment of the invention, the magnitude of the second value is a constant value.

Abstract: An apparatus and method for controlling the engagement rate of a clutch in a partially or fully automated mechanical transmission in response to an indication provided by the driver, such as the depression of an accelerator pedal of the vehicle. The apparatus includes an electronic controller which initially sets a desired speed for the vehicle engine during the shifting process, determines a rate of engagement movement of a release bearing of the clutch, and actuates appropriate valves to initiate the gradual engagement of the clutch. The electronic controller is responsive to the position of the accelerator pedal of the vehicle for adjusting the rate of engagement of the release bearing of the clutch. In a first embodiment, the electronic controller is responsive to movement of the accelerator pedal in a first direction (depressed for further acceleration) for incrementing the rate of engagement of the release bearing.

Abstract: An apparatus and method for controlling the operation of a clutch in a partially or fully automated mechanical transmission which is responsive to the actual speed of the vehicle engine for varying the engagement rate of release bearing during reengagement of the clutch. The apparatus includes an electronic controller which initially sets a desired speed for the vehicle engine during the shifting process, determines a rate of engagement movement of a release bearing of the clutch, and actuates appropriate valves to initiate the gradual engagement of the clutch. The electronic controller sets a first lower engine speed threshold and a second lower engine speed threshold. The magnitude of the first lower engine speed threshold may vary with the amount of depression of an accelerator pedal of the vehicle. If the actual speed of the engine remains above both the first lower engine speed threshold and the second lower engine speed threshold, the engagement process is continued without interruption.