Ford Global Technolgoies, LLC

Timothy L Sargent

Hong Jiang

Zhengyu Dai

Yang Xu

Weitian Chen

Joseph F Kucharski

Guopeng Hu

John G Fowler

Michael William Brylinski

A vehicle includes an engine with an associated engine-speed sensor, and wheels each having a respective wheel-speed sensor. The vehicle also includes a continuously variable transmission (CVT) coupled to the engine and configured to operate at variable input-to-output ratios. At least one controller is programmed to reduce the operating ratio of the CVT in response to the engine-speed sensor indicating the engine is operating at idle speed and the wheel-speed sensor indicating the velocity is approximately zero. This provides less noise, vibration and harshness in the vehicle due to the reduced ratio that is possible during conditions in which a vehicle launch in that reduced ratio may not be acceptable.

Continuously variable transmission (CVT) ratio control

A method of controlling a Continuously Variable Transmission (CVT) simulates a step-ratio transmission upshift. To simulate a step-ratio torque phase, the input torque is gradually reduced before beginning to change the variator ratio. Then, as the variator ratio is changed, the input torque is gradually increased to compensate for the decreasing torque ratio, simulating the relatively constant output torque of an inertia phase of a step-ratio upshift.

Method of shifting a transmission

During state transitions, a clutch actuator position command includes an oscillating component called a dither. This dithering helps avoid jumps in the actuator position due to friction when the commanded position is changed gradually. Also, dither during a transition from fully released to slipping causes the natural frequency of the system to change gradually rather than abruptly. This permits use of another slipping clutch for active damping based on a measured oscillation.

Clutch control using dither

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Northville, MI, United States of America

Timothy L Sargent