An Automated Manual Transmission (AMT) system is generally constituted by a dry or wet clutch assembly and a multi-speed gearbox, both equipped with electro-mechanical or electro-hydraulic actuators, which are driven by a control unit, the transmission control unit (TCU). The operating modes of AMTs are usually two: semiautomatic, with the driver requesting a sequential gear shift by means of a proper interface or fully automatic. In both cases, after the gear shift command, the TCU manages the shifting steps, through suitable signals to the engine, the clutch assembly and the gearbox, according to current engine regime, driving conditions and selected program. For market sectors such as large-series and ecological cars, AMT has the advantage of lower weight and higher efficiency with respect to other typologies of automatic transmissions. Furthermore, an AMT is directly derived from a manual one through the integration of actuators; then, development and production costs are generally lower than other automatic transmissions, while the reliability and durability are at highest level. For high class sport cars, vehicle dynamic performances and driving quality can further improve the results of the automatic transmissions . This transmission type is also an affordable and robust solution, but the quality of the vehicle propulsion as perceived by the driver is largely dependent on the quality of the control strategies. Furthermore, sensitivity analyses on control schemes for AMTs have shown that uncertainties in clutch torque characteristic can severely affect the performance of the clutch engagement: modelling in detail the torque transmitted by the specific clutch architecture is a crucial issue in order to design robust engagement control strategies [2, 3]. This paper aims at investigate the temperature influence on the dry clutch transmission characteristic through the study of physical models which separately taking into account the thermal effect on the frictional behaviour of the clutch facings, the throwout bearing characteristic positions, the cushion spring load-deflection curve. The outcome of this analysis could become a key element for designers of automated clutches and control engineers to recast the cushion spring conception to overcome the poor engagement performance exhibited by AMTs after repeated gear shifting.
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