Study of a Dynamic Proportional Combined Brake System for Scooters

• Main Authors: Chiu, Yuh-Siang, 邱昱翔
• Other Authors: Tseng, Chyuan-Yow
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/21658414796952264978

碩士 === 國立屏東科技大學 === 車輛工程系所 === 103 === Because of higher agile and more convenience compared with four-wheel vehicle, two-wheel motorcycle is the most popular transportation that used in Taiwan. For the motorcycle, braking system is one of the critical parts to ensure driver’s safety. The brake system in four-wheel vehicle is with integrated braking system. When drivers step on the brake pedal, all the four wheels produce braking force simultaneously. But most of the two-wheel vehicles are equipped with separate braking system, that is, drivers pull the left brake handle bar to produce the rear braking force, while the right handle bar produces front brake force. Since most of the drivers were not trained well, a lot of unpredictable rollover dangerous were occur because the drivers accidentally pull the right handle first instead of the left one. Therefore it is regulated by governments in many countries that all the scooters must be equipped with ABS or combined brake system (CBS). With those two advanced systems (ABS and CBS), the drivers could execute single handle/pedal to initiate both the front and rear braking system to produce brake forces simultaneously. Currently, most of the CBS designs are of fixed proportional braking force type between the front and rear wheels. When apply this system to drum brake systems, a larger gap between the brake drum and brake shoe resulting from shoes wearing may cause rear wheel lack of brake force and, meanwhile, front wheel locked. This is a critical failure mode existing in the CBS that may cause safety problem. Furthermore, because of comfort and drivability considerations, and the effect of the load transfer phenomena during brake, it is required that the rear brake force should larger than the front wheel at initial braking operation stage. On the other hand, the front wheel should take larger brake force than the rear wheel at higher deceleration brake operations. The fixed proportional CBS is generally unable to offer these requirements. In this thesis, a dynamic proportional combined braking system (DPCBS) and automatic drum gap compensation (DGC) device for drum brake system are studied. Here, the DPCBS system is used to distribute the brake forces between front and rear wheel dynamically according to the pull force amplitude of the driver’s handle bar. The DGC is designed for compensating the gap variations between the brake drum and shoes. This thesis is focused on the development of the DPCBS and the DGC, under the considerations of cost, reliability, and durability. The works include motorcycle dynamics, mechanical design, and prototype testing. The experimental results have shown that the DPCBS could determine the proportion of front and rear wheel brake forces appropriately depending on the amount of the pull force of the brake handle bar. The DCG could adjust the gap for a worn brake shoes efficiently, with a success rates up to 99%.