| Summary: | 博士 === 國立交通大學 === 機械工程系 === 92 === A common problem on a current bicycle hydraulic disc brake system is that the unwanted friction may occur during free running if the lining pad does not depart away from the disc rotor. This friction may induce vibration, noise, power consumption, higher operating temperature and the braking force reduction. Another problem is that the improper braking force by the rider may induce slippage between the tire and road surfaces in the circumstances of inferior road surface conditions. This slippage may lead to chassis spin, yaw and increase the stopping distance. Aimed at these problems, this study collects relevant literatures, theoretically acquaints their operating principles and inducts possible research directions. By utilizing these remarks, this study proposes two solutions for brake systems by utilizing the methodology of creative design. The first solution is a caliper piston retractor that focuses on the lining pad departure from the disc rotor, reducing the drag force during non-braking mode. The second solution is a hydraulic pressure regulator that can modulate the pressure in the caliper, preventing the excessive pressure in the master cylinder applied by the rider from entering the caliper. This regulation can result in a reduced possibility of tire slippage on the road surface and intensify the effectiveness of stopping the vehicle if cooperating with a suitable control algorithm. The design, manufacturing and assembly processes of a bicycle brake system test rig are accomplished in another phase of this study to examine these apparatus performances.
The retracting stroke of the piston retractor is achieved and pre-definable for designers or manufacturers by modifying the design parameters in the evaluative production stage. Therefore, designers can provide users a maintenance-free usage of this product after the product marketing stage. This stroke adjustment characteristic helps users to reduce the possibility of brake performance variations when inferior tuning. The pressure regulator can reduce the hydraulic pressure in the caliper via a solenoid-controlled fluid passage. Compared with current automobile or motorcycle hydraulic pressure regulators, the proposed design provides lower operating frequency, yet it is small in size, economical in electric power consumption and light in weight. This regulator can be equipped on a lightweight motorcycle or bicycle with proper control algorithms. Finally, the proposed brake system test rig is verified with experiment results. The test rig is also utilized to examine the performances of the piston retractor and the hydraulic pressure regulator. Their experiment results show that the new designs can solve the problems and achieve their aims, respectively, on the bicycles for the hydraulic disc brake system.
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