Detailed Modeling and Experimental Assessments of Automotive Dry Clutch Engagement

The characteristics of the clutch engagement process would have significant influences on the torque transmissibility and operation comfort. However, some crucial components are simplified in many previous literature, which would cause imprecision. Therefore, it is important to build a detailed mathematical model of these components and inspect the whole process of clutch engagement. In order to improve the torque transmissibility and achieve better pedal releasing comfort, solutions based on the modeling of the clutch cover assembly and the friction disc assembly, the analysis of the clamping force and the releasing characteristics of the release bearing are proposed in this paper. Furthermore, models of the crucial components such as the diaphragm spring, which connects the straps and cushion plate, are built and the corresponding mechanical properties are analyzed. Based on the manufacturing tolerance, the life cycle, and the wear properties, diaphragm spring correction formula is proposed by referring to Almen-Laszlo method. On the system level, the whole engagement process is divided into four stages because of the differences between the engaging and disengaging processes, which would affect the pedal releasing comfort in the manual transmission system and the shifting quality in the automated transmission system. To demonstrate the effectiveness of the proposed method, detailed mathematic models are built and the corresponding experiments are conducted.