| Summary: | 博士 === 國立臺北科技大學 === 機電科技研究所 === 96 === In this study, the friction force of polytetrafluroethylene (PTFE) seal for vehicle brake tandem master cylinder is evaluated through experimental tests, using the proposed testing system.
The friction force of seal between exterior aluminum wall and interior piston is typically a combination of several friction regions and the contact friction can be divided into solid friction, boundary lubrication and hydrodynamic lubrication. The static friction force and stick-slip effect is considered as a crucial step to form vibration and predict the life time of the V-shaped seal. The behavior of an elastomeric seal for vehicle Tandem master cylinder is measured and analyzed in velocity by using three types of nanoparticles brake fluids made by our laboratory. Working conditions are simulated for different piston rod velocity and cylinder supply pressure.
The results show that nanoaluminum oxide brakefluid with its ball shape can highly reduce friction force to avoid seal excessive wear and reduce slick slip in brake applications. The solid friction force can be reduced by the assistance of the rollingof nanoparticles. Besides, the generalized Sommerfield number in lubrication theory, S0, is increased by the nanoparticles added and increased viscosity. The solid friction is lower due to nanoparticles rolling during the movement start. The nanoparticles provide function of rolling, mend surface and increasing viscous in order to being good lubricants. Accordingly, the friction force is about 3% lower than that without adding nanoparticles in brake system. The frequency and the magnitude of stick-slip are lower than that without adding nanoparticles in brake system. The outstanding physical properties in the operation of vehicle brake master cylinder will lead to reduce the seal excessive wear and reduce stick slip in brake applications.
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