Importance

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Abstract

A friction clutch assembly in an automotive vehicle transmission is located between an engine-driven input shaft and a torque input shaft for a multiple ratio transmission. A clutch spring normally applies a clutch engaging force to the clutch assembly, thus establishing a torque flow path between the input shaft and the multiple ratio gearing. An electromechanically actuated ball ramp mechanism applies a friction clutch release force to the friction clutch assembly, thereby interrupting the torque flow path between the transmission input shaft and the multiple ratio gearing. An electromagnetic clutch actuator for the ball ramp mechanism, when it is energized, actuates the ball ramp mechanism to disengage the friction clutch. One element of the ball ramp mechanism is grounded to a transmission housing when the electromagnetic actuator is energized. Precise slip control of the friction clutch is achieved by modulating the energizing current for the electromagnetic actuator, thereby providing improved start-up performance and improving shift quality as ratio changes occur in the manual transmission.

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First Claim