| After nearly 200 years of development, Bicycle, initially as a luxury, later as a means oftransport, and now as a recreational tool with a variety of styles, is playing an important rolein people’s lives. People on bikes have become increasingly demanding. From the initial thereto meet, to the requirements of easy to use, now it is required to have precise performance.Bicycle brakes, as one of the important properties, develop from the V brakes on the steelring, drum brakes on the shaft, to nowadays disc brakes. In the domestic and Europeanbicycle standards, there are strict requirements for bicycle brake performance, and twomethods for testing bicycle brake are proposed, road test and machine test. A survey wasmade and found that in domestic manufacturers of production and design disc, road test wasgenerally applied to test the product, but the test conditions were not in accordance with therequirements of European standards. On the bicycle used to test the performance of bicyclebrakes, the speedometer and the distance recording devices were not installed; theperformance evaluation totally depended on the brake tester’s subjective judgments. Not onlythis method had great randomness and testers were prone to falls and other accidents,especially when the product was in the immature stage.To solve this problem, a test system was developed for bicycle disc brake. This testsystem not only had more accurately, but also avoided the injury for the testers in the testingprocess. The system’s main function was to measure the brake force between disc brake padsand the distance of bicycle disc brake. The main contents were as follows:At the beginning, the introduction about bicycle disc brake was made, including thecomposition and classification of bicycle disc brake. Then the technical requirements forbrake performance testing were analyzed. According to these requirements, the overallframework of the test system for disc brakes was proposed. The test system can be dividedinto braking force detection system and the braking distance test system.The first part was the braking force detection system. It was composed of tensionmeasurement of the brake cable, pressure measurement between the brake pads, PC softwaredesign and so on. The key issue of this part was to measure the pressure between the brakepads. As the gap between the brake pads was less than 3 mm, so the thin-film sensors wereused to measure the gap. Before using, the thin-film sensors needed to be calibrated. So thecores of this part included the design of calibration equipment, the selection of calibrationalgorithm and the implementation of selected algorithm. The second part was the braking distance test system. It was composed of the equivalentanalysis of the inertia plate simulating bike run, the design of test system and detect system,PC software design and so on. The key technologies of this part included the way to controlspeed, the method to find the braking points and the braking distance calculations. Theprocess of completing braking distance testing was controlled by PC software. On the PCscreen, the speed was showed real-timely and the braking distance and the braking time wereshowed after a braking process completed.Finally, the verification was made in a domestic manufacturer of production and designdisc. The results of the braking force detection system show the measurement error of thecalibrated thin-film sensors is within 10%. The magnification of disc brake can be stabilitymeasured with the calibrated thin-film sensors and the tension sensor. The detection ofbraking force achieves the desired design requirements. The results of the braking distancetest system show the measurement error of the braking distance is within 12%, the operationin a long time is stabile. The measure of the braking distance achieves the desired design goal.The whole results indicate that the system can be stable to perform, easy to operate andpractical. This set of test system for the bicycle disc brake has good application value. |
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