METHOD AND APPARATUS FOR OPERATING A CLUTCH IN AN AUTOMATED MECHANICAL TRANSMISSION

摘要

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. In a first embodiment, the electronic controller 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 first constant value. If so, it can be inferred that the clutch is sufficiently close to full engagement as to warrant the interruption the gradual engagement process and immediately move the release bearing from its current position to the fully engaged position. To avoid a false inference of full engagement, the clutch input or output shaft speed signal is compared with the desired engine speed signal. When the magnitude of the difference between the clutch input shaft speed signal and the desired engine speed signal is less than a second constant value, then the inference that the clutch is sufficiently close to full engagement is confirmed. Thus, the release bearing can be immediately moved from its current position to the fully engaged position. In a second embodiment, an updated difference signal (calculated as the difference between an updated clutch input shaft speed signal and an updated clutch output shaft speed signal) is compared with a previous difference signal. An error signal is calculated as the difference between the updated difference signal and the previous difference signal. The electronic controller controls the movement of the release bearing such that the error signal closely follows a selected clutch engagement profile so as to consistently engage the clutch.