자기 강화 메커니즘을 이용한 클러치 토크 추정

Abstract

In modern transmission control, fast and smooth shifting is the most important issue. Efficient power transfer requires fast shifting, and accurate slip control is necessary to improve the driver's ride comfort. In order to improve the slip control performance, it is very important to know the clutch torque. A clutch torque can be known from the clutch disk pressure and torque friction coefficient. The pressure applied to the clutch disk can be measured from the motor current and the force sensor. However, the torque friction coefficient cannot be measured by the sensor. Also, the friction coefficient is unknown because it changes with temperature, slip speed, and pressure on the clutch disk. Therefore, clutch torque estimation with the indirect method has been actively studied. In the forward-direction clutch torque estimation through the engine torque, the exact clutch torque cannot be estimated because the engine torque is inaccurate. Also, the backward-direction clutch torque estimation method using the compliance model has a disadvantage in that the clutch torque cannot be estimated when there is a backlash of the gear. Thus, in this manuscript, we propose a clutch disk torque friction coefficient estimation with a ball-ramp self-energizing mechanism. In the self-energizing mechanism in which the torque caused by friction reinforces the normal force, the gain of the actuator force to the clutch normal force varies according to the friction coefficient. Apply the actuator's position and force to the model to obtain the change in gain and estimate the clutch disc torque friction coefficient. he ball-ramp actuator is modeled for the torque friction coefficient estimation, and the test bench experiment verifies the clutch torque estimation performance during shifting. Finally, verification of the proposed model and estimation of the clutch disc torque friction coefficient during shifting are conducted via test bench experiments.