【正文】 教會(huì)我專業(yè)知識，才使我順利完成這次畢業(yè)設(shè)計(jì)。 test bench。 high values at the beginning and end are from the trigger signal。 mounting construction, 7. hub with mounted brake disc, 8. direction change for the wire rope, 9. brake lever, key, 11. water reservoir to collect splash water, 12. lever arm assemblyThe hand force is produced with a Fluidic Muscle (Festo AG amp。hler GmbH, Weisse Breite 7, 49084 Osnabruck, Germany), an average pulling velocity of the brake lever under resistingforce of the brake system was found to be . Three different subjects were tested with the advice to pull five times as fast and hard as possible. One subject activated the brake with two fingers, two with one. The maximum releasing velocity was between and .3. ConstructionWith the measured values the test bench could be dimensioned. To get an advantage in parison to the outdoor tests, the whole test process has to be precise, guarantee constant conditions, requires a small number of test personnel as well as having a fast throughput. The concept was to use a powerful threephase engine with a worm gear (Fig. 4 , 3 and 4) on whose shaft a hub (Fig. 4, 7) with the brake disc is mounted. The force values are measured with two load cells, one for the hand force and one for the resulting brake force. Controlling is done with a realtime controller system (pactRIO cRIO9073, a real time controller including FPGA) and a LabView2009 application (National Instruments, Austin, TX, USA)Fig. 4 overview of the test bench。 additional the wheel radius (rl) is shown.The most important mechanical difference of these two categories (rim and hub brakes) is the acting radius (rr),which is important for the brake torque as shown in Fig. 2. The smaller the acting radius is, the higher the friction force has to be to produce enough brake torque, which decelerates the rider. To get the same brake force, the friction force of a disc brake (rotor diameter 160mm) produced by the friction of the brake pads and the brake disc is about times higher, pared to a rim brake between brake pads and rim to equalize the shorter lever arm. A realistic brake force at the front wheel, when a bicycle rider (80kg) in upright position (it depends on the position and the geometry of the bike) does a rollover, is in the region of about 400N. To produce this brake force, a disc brake with a 160mm rotor needs to produce a friction force of about 1666N. Calculating with a friction coefficient of about , the applied force, which pushes the brake pads against the brake disc must be 3332N. If the rider is heavier and shifts his center of mass backwards, the possible brake forces can rise up to over 700N (measured). This brake force is produced by possible hand forces of about 100150N. Basing on 400N rollover force and an applied hand force of about 80N means, the overall transmission ratio of the brake (mechanical and hydraulic ratio) is about 4045.2. Measurements and results for the dimensioningThe key factors to construct a well designed test bench are the knowledge of the appearing mechanical values, such as the maximum brake torque, the applied hand force and the velocity of the brake lever. To find out these values several measurements took place. To find out the reachable brake torque or brake force, two different approaches were chosen. One was to check the maximum reachable value of the deceleration with the help of a threedimensional acceleration sensor, which was placed on the top tube of the main frame of a mountain bike. The measurement setup was built out of a sensor platform called “Neon” (Spantec GmbH, Gumpendorferstrasse 132/2/5, 1060 Vienna, Austria). This sensor platform does a 10bit a/d conversion and records the data on an SDcard or digitally transmits them via ANT+ wireless munication to a puter. The chosen threedimensional acceleration sensor type was MMA7260Q (Freescale Halbleiter Deutschland GmbH, Schatzbogen 7, D81829 Munich, Germany). Its measurement range was set to +/1,5g.Fig. 3 Acceleration measurement showing a maximal braking when just using the front disc brake (Avid Juicy seven, 203mm rotor) of a mountain bike. Positive values representing deceleration。 disc brake。在設(shè)計(jì)的過程中遇到了很多的困難和障礙，都在同學(xué)和老師的幫助下解決了，在這里首先要感謝我的指導(dǎo)老師王老師，老師從放暑假時(shí)就給了我們許多資料，讓我們先了解有關(guān)設(shè)計(jì)課題的知識，并且在我做畢業(yè)設(shè)計(jì)的每個(gè)階段，從查閱資料到設(shè)計(jì)草案的確定、修改、中期檢查，不厭其煩的幫助我進(jìn)行設(shè)計(jì)的修改和改進(jìn)。： 式中：相對剛度系數(shù)，見下表：表47墊片材料金屬（無墊片）皮革銅皮石棉橡膠可得： 得： 螺栓的許用應(yīng)力幅: 式中：—尺寸因數(shù)，； —螺紋制造工藝因數(shù)，； —受力不均勻因數(shù)，； —螺栓材料的疲勞極限，見表45； —缺口應(yīng)力集中因數(shù)，； —安全因數(shù)，；得： 計(jì)算結(jié)果：滿足，所以安全。 使47 得： 齒根許用彎曲應(yīng)力： （411） —抗彎強(qiáng)度的計(jì)算安全系數(shù)，； 式411得： 計(jì)算結(jié)果：滿足的強(qiáng)度條件，安全。而且要用螺栓13來固定。 圖41 設(shè)計(jì)的制動(dòng)器整體結(jié)構(gòu)方案 11動(dòng)壓盤 12后輪轂螺栓 13螺栓 局部零件設(shè)計(jì)方案 摩擦片選取及布置用于制動(dòng)器的摩擦材料，通常在很高的剪力和溫度條件下工作，要求這類材料能吸收動(dòng)能，并將動(dòng)能轉(zhuǎn)化熱能散發(fā)到空氣中。,因呈線性關(guān)系，所以有式（313）存在，可知、的變形量、： (316)得： (317)打開摩擦片所需間隙為: (318)： (319)將（317）代入上式，求得：,所以取15對合： (320)： （321）：方案二的計(jì)算：，碟簧組組數(shù)，鋼片粉片間隙值。如下圖：圖31 :由n個(gè)相向同規(guī)格的碟簧組成。3. 碟形彈簧由于改變碟片數(shù)量或碟片的組合形式，可以得到不同的承載能力和特性曲線，因此每種尺寸的碟片，可以適應(yīng)很廣泛的使用范圍，這就使備件的準(zhǔn)備和管理都比較容易。 整車制動(dòng)力矩計(jì)算 制動(dòng)減速度的計(jì)算 ： (31)：表31 制動(dòng)類型延遲時(shí)間的選取制動(dòng)類型時(shí)間彈簧制動(dòng)液壓盤式制動(dòng)多片制動(dòng)氣壓制動(dòng)～鼓式制動(dòng)選取彈簧制動(dòng)由表（31），得到： (32)此時(shí)因制動(dòng)延遲運(yùn)行的制動(dòng)距離為： (33)由（31）、（32）知最大制動(dòng)減速度: (34) 整車所需的最大制動(dòng)力矩的計(jì)算 :—整車工作質(zhì)量（kg）—輪胎半徑（m）—最大制動(dòng)減速度(m/s2)所以： （35）: (36)選取最大整車制動(dòng)力矩： （37）考慮一定的制動(dòng)扭矩設(shè)備，～,；可得知整車最大制動(dòng)力矩為: （38）按照制動(dòng)時(shí)載荷分配可知制動(dòng)前后橋所需制動(dòng)力矩為：