• Advances in Automotive Engineering
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• v.1 no.1
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• pp.21-39
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• 2018

Clutch energy is the thermal energy dissipated on the clutch disc, and it reaches its highest level during drive-off as a result of the difference between the angular speeds of the flywheel and clutch disc, and the torque transmitted. The thermal energy dissipated effects the clutch life. This study presents a new drive-off and thermal model to calculate the clutch energy for a rear wheel driven heavy-duty vehicle and to analyze the effects of clutch energy on temperatures of clutch pressure plate, flywheel and clutch housing. Three different driver profiles are used, based on the release of the clutch pedal in modulation zone: i) the pedal travels with the same speed all the way, ii) the travel speed of the pedal increases, iii) the travel speed of the pedal decreases. Vehicle test is performed to check the accuracy of the model. When compared to a simpler model that is widely used in the literature to calculate the clutch energy, the model used in this study calculates the clutch energy and angular speed behaviors of flywheel and transmission input shaft in better agreement with experimental results. Clutch wear and total clutch life are also estimated using the mean specific friction power.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.4
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• pp.32-38
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• 2006

A clutch hydraulic system for automotive manual transmissions transfers hydraulic pressure generated by driver's pedal manipulation to the clutch mechanism. The foot effort when the clutch pedal is pushed is different than that when the clutch is returned. The effort or load difference, called hysteresis, is caused by the friction produced between rubber seal and inner wall inside the hydraulic cylinder. This clutch pedal travel foot effort hysteresis is essential for a clutch hydraulic system design and analysis. The dynamic model for a clutch hydraulic system is developed and a simulation analysis is performed to estimate the fiction coefficient as a function of the cylinder pressure. The simulation result is then compared to the measurements obtained from a clutch hydraulic system tester to ensure the reliability of the dynamic model and the coefficients estimated. Also the estimated friction coefficients at various pressure values are compared to those reported by an independent study.

• Journal of KSNVE
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• v.11 no.3
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• pp.461-470
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• 2001

A friction-type clutch system sometimes generates spick-slip vibration during engagement, which disturbs smooth start of a car and makes a passenger uncomfortable. In this study, the spick-slip vibration in four types of friction couples was investigated at two different engagement conditions respectively of which the amount of slip time and clutch travel was varied. Results are found as follows. First, the vibration increased at the condition of small engine torque and large torque fluctuations due to higher harmonics of engine speed. Second, the friction couple without a pre-damper has advantages of reducing the vibration. This study also suggested an evaluation method of vehicle vibration in the view point of human perception by using the frequency weighting of ISO2631-1.