【正文】 才成為社會(huì)較緊缺、企業(yè)最需要的人才。企業(yè)對(duì)較高層次的第一線應(yīng)用型人才的需求將明顯增加，培養(yǎng)相當(dāng)數(shù)量的具有高等文化水平的職業(yè)人才，成為迫切要求。完全靠駕駛員手力操縱的轉(zhuǎn)向系統(tǒng)稱為機(jī)械轉(zhuǎn)向系統(tǒng)。淺析汽車轉(zhuǎn)向系統(tǒng)常見故障診斷與維修開題報(bào)告一、背景、現(xiàn)狀及發(fā)展趨勢(shì)轉(zhuǎn)向系統(tǒng)：用來改變或保持汽車行駛方向的機(jī)構(gòu)稱為汽車轉(zhuǎn)向系統(tǒng)(steering system)。汽車轉(zhuǎn)向系統(tǒng)分為兩大類：機(jī)械轉(zhuǎn)向系統(tǒng)和動(dòng)力轉(zhuǎn)向系統(tǒng)。隨著產(chǎn)業(yè)布局、產(chǎn)品結(jié)構(gòu)的調(diào)整，就業(yè)結(jié)構(gòu)也將發(fā)生變化。這表明，我們的高級(jí)技工在未來5—10年內(nèi)仍會(huì)有大量的人才缺口。通過本次畢業(yè)論文對(duì)轉(zhuǎn)向系統(tǒng)進(jìn)行進(jìn)一步的了解，并且結(jié)合通過實(shí)習(xí)了解的知識(shí)對(duì)轉(zhuǎn)向系統(tǒng)的可能出現(xiàn)的問題進(jìn)行分析和解決方法，從而提高自身對(duì)轉(zhuǎn)向系統(tǒng)的深入認(rèn)識(shí)二、設(shè)計(jì)目的　　通過本次畢業(yè)設(shè)計(jì)使自己對(duì)汽車轉(zhuǎn)向系統(tǒng)在故障診斷和維修方面有更為充分、細(xì)致的理解，進(jìn)一步掌握轉(zhuǎn)向系統(tǒng)的原理、應(yīng)用和CAD/CAM軟件應(yīng)用。起作用是使汽車在行駛過程中能按照駕駛員的操縱要求而適時(shí)地改變其行駛方向，并在受到路面?zhèn)鱽淼呐既粵_擊及汽車意外地偏離行駛方向時(shí)，能與行駛系統(tǒng)配合共同保持汽車?yán)^續(xù)穩(wěn)定行駛。汽車轉(zhuǎn)向系統(tǒng)對(duì)汽車的行駛安全至關(guān)重要，因此汽車轉(zhuǎn)向系統(tǒng)的零件都稱為保安件。這一套用來改變或恢復(fù)汽車行駛方向的專設(shè)機(jī)構(gòu)，即稱為汽車轉(zhuǎn)向系統(tǒng)。動(dòng)力轉(zhuǎn)向系統(tǒng)又可分為液壓動(dòng)力轉(zhuǎn)向系統(tǒng)和電動(dòng)助力動(dòng)力轉(zhuǎn)向系統(tǒng)。駕駛員對(duì)轉(zhuǎn)向盤施加的轉(zhuǎn)向力矩通過轉(zhuǎn)向軸輸入轉(zhuǎn)向器。這里，轉(zhuǎn)向橫拉桿和轉(zhuǎn)向節(jié)臂屬于轉(zhuǎn)向傳動(dòng)機(jī)構(gòu)。　　　轉(zhuǎn)向傳動(dòng)機(jī)構(gòu)的功用是將轉(zhuǎn)向器輸出的力和運(yùn)動(dòng)傳到轉(zhuǎn)向橋兩側(cè)的轉(zhuǎn)向節(jié)，使兩側(cè)轉(zhuǎn)向輪偏轉(zhuǎn)，且使二轉(zhuǎn)向輪偏轉(zhuǎn)角按一定關(guān)系變化，以保證汽車轉(zhuǎn)向時(shí)車輪與地面的相對(duì)滑動(dòng)盡可能小。當(dāng)外轉(zhuǎn)向輪偏轉(zhuǎn)角達(dá)到最大值時(shí)，轉(zhuǎn)彎半徑R 最小。圖15 隨著車速的提高，現(xiàn)代汽車的轉(zhuǎn)向輪有時(shí)會(huì)產(chǎn)生擺振（轉(zhuǎn)向輪繞主銷軸線往復(fù)擺動(dòng)，甚至引起整車車身的振動(dòng)），這不僅影響汽車的穩(wěn)定性，而且還影響汽車的舒適性、加劇前輪輪胎的磨損。機(jī)械轉(zhuǎn)向系的常見故障主要包括：轉(zhuǎn)向沉重，轉(zhuǎn)向盤自由行程過大和轉(zhuǎn)向輪抖動(dòng)。②轉(zhuǎn)向輪本身定位不準(zhǔn)或車軸、車架變形造成轉(zhuǎn)向輪定位失準(zhǔn)，應(yīng)校正車軸和車架，并重新調(diào)整轉(zhuǎn)向輪定位。⑥轉(zhuǎn)向器殼體變形，應(yīng)予校正。 故障診斷方法以桑塔納乘用車為例，先檢查輪胎氣壓，排除故障由輪胎氣壓過低引起。具體表現(xiàn)為汽車轉(zhuǎn)向時(shí)感覺轉(zhuǎn)向盤松曠量很大，需用較大的幅度轉(zhuǎn)動(dòng)轉(zhuǎn)向盤，方能控制汽車的行駛方向；而在汽車直線行駛時(shí)又感到行駛方向不穩(wěn)定。③轉(zhuǎn)向垂臂與轉(zhuǎn)向垂臂軸連接松曠，應(yīng)予調(diào)整。⑦車輪輪轂軸承間隙過大，應(yīng)予更換等。 故障主要原因及處理方法轉(zhuǎn)向輪抖動(dòng)的根本原因是轉(zhuǎn)向輪定位不準(zhǔn)，轉(zhuǎn)向系連接部件之間出現(xiàn)松曠，旋轉(zhuǎn)部件動(dòng)不平衡。④轉(zhuǎn)向系與懸掛的運(yùn)動(dòng)發(fā)生干涉，應(yīng)予更換部件。⑧轉(zhuǎn)向輪所在車軸的懸掛減振器失效或左右兩邊減振器效能不一，應(yīng)予更換。 動(dòng)力轉(zhuǎn)向系故障診斷為了操縱輕便，轉(zhuǎn)向靈敏和提高行車安全，目前高級(jí)乘用車、豪華客車和重型貨車廣泛圖22 機(jī)械轉(zhuǎn)向系轉(zhuǎn)向輪抖動(dòng)常見故障原因的診斷流程采用了動(dòng)力轉(zhuǎn)向系。 轉(zhuǎn)向沉重 故障現(xiàn)象同機(jī)械轉(zhuǎn)向系。③油路中有泄漏現(xiàn)象，應(yīng)予檢修排除。⑦轉(zhuǎn)向機(jī)構(gòu)調(diào)整不當(dāng)，應(yīng)予調(diào)整等。圖23 動(dòng)力轉(zhuǎn)系轉(zhuǎn)向沉重助力部分常見故障原因的診斷流程 轉(zhuǎn)向噪聲 故障現(xiàn)象汽車轉(zhuǎn)向時(shí)，轉(zhuǎn)向系出現(xiàn)過大的噪聲。③控制閥性能不良，應(yīng)予檢修。轉(zhuǎn)向時(shí)發(fā)出“嘎嘎”聲，由轉(zhuǎn)向泵傳動(dòng)帶打滑引起。故障原因主要是：系統(tǒng)內(nèi)有空氣或壓力限制閥失效。）、汽車最小轉(zhuǎn)彎半徑（m）、轉(zhuǎn)向輪定位參數(shù)等。依靠人工經(jīng)驗(yàn)很難判斷轉(zhuǎn)向盤的轉(zhuǎn)向力和自由轉(zhuǎn)動(dòng)量是否正確，可以使用專門儀器來檢測(cè)。轉(zhuǎn)向輕便性可用一定行駛條件下作用在轉(zhuǎn)向盤上的轉(zhuǎn)向力（即作用在轉(zhuǎn)向盤外緣的最大切向力）來表示，采用轉(zhuǎn)向參數(shù)測(cè)量?jī)x可以測(cè)得轉(zhuǎn)向盤轉(zhuǎn)向力。 檢測(cè)轉(zhuǎn)動(dòng)操縱盤，轉(zhuǎn)向力通過底板、力矩傳感器、連接叉?zhèn)鬟f到被測(cè)轉(zhuǎn)向盤上，使轉(zhuǎn)向盤轉(zhuǎn)動(dòng)。 結(jié)果分析按GB/T ，路試時(shí)檢測(cè)轉(zhuǎn)向盤最大轉(zhuǎn)向力采用如下方法：汽車空載在平坦、干燥和清潔的硬路面上，以10 km/h的速度在5s之內(nèi)沿螺旋線從直線行駛過渡到直徑為24m的圓周行駛，施加于轉(zhuǎn)向盤外緣的最大切向力不得大于150 N。轉(zhuǎn)向盤自由轉(zhuǎn)動(dòng)量過大時(shí)，將造成駕駛員工作緊張，并影響行車安全。使用該種檢測(cè)儀時(shí)，應(yīng)使汽車保持直線行駛位置不動(dòng)，轉(zhuǎn)動(dòng)轉(zhuǎn)向盤至一側(cè)極限位置，將刻度盤歸零，再輕輕轉(zhuǎn)動(dòng)轉(zhuǎn)向盤至行程另一側(cè)極限位置，指針?biāo)究潭燃礊檗D(zhuǎn)向盤自由轉(zhuǎn)動(dòng)量。圖31 轉(zhuǎn)向盤自由行程的調(diào)整1—鎖緊螺母；2—調(diào)整螺栓；3—鎖片；4—鎖緊螺母；5—調(diào)整螺母 潤(rùn)滑萬向節(jié)。（3）檢查調(diào)整齒輪、齒條配合間隙。然后將調(diào)整螺栓鎖止。轉(zhuǎn)向器潤(rùn)滑油一般每隔8000 km檢查添加，48 000 km更換；每隔2000 km潤(rùn)滑轉(zhuǎn)向傳動(dòng)軸。桑塔納、奧迪等乘用車都使用齒輪齒條式轉(zhuǎn)向器，其結(jié)構(gòu)與天津夏利乘用車轉(zhuǎn)向器基本相同。④將轉(zhuǎn)向齒條接頭螺母松開，從轉(zhuǎn)向齒條殼體上拆下轉(zhuǎn)向接頭螺母，再用專用工具拆卸鎖緊螺母。⑦用螺絲刀拆下油封，注意不要?jiǎng)潅麣んw。（2）檢修①檢查齒條的擺差、齒的磨損情況；。（3）裝配與調(diào)整①裝配前注意在各密封處、相互運(yùn)動(dòng)處加注潤(rùn)滑脂。用專用工具將轉(zhuǎn)向小齒輪裝入齒條殼體內(nèi)，然后裝上孔用彈性擋圈，再用專用工具將油封壓入齒條殼體內(nèi)。⑤調(diào)整齒條預(yù)緊度。m。⑥裝配轉(zhuǎn)向齒條接頭總成。裝上轉(zhuǎn)向齒條防塵罩，裝上防塵罩鎖簧和防塵罩箍帶。循環(huán)球式轉(zhuǎn)向器正傳動(dòng)效率可達(dá)90%95%，操縱輕便，使用壽命長(zhǎng)，在貨車上得到廣泛應(yīng)用。 轉(zhuǎn)向傳動(dòng)機(jī)構(gòu)的修理（1）拆卸與分解①分開轉(zhuǎn)向搖臂與直拉桿。（2）檢修①檢查轉(zhuǎn)向搖臂或上端花鍵有無裂紋或損壞，若有應(yīng)更換。⑤檢查轉(zhuǎn)向節(jié)應(yīng)無裂紋，軸頸與軸承的配合間隙符合要求。放入球頭座，擰入螺塞；擰緊時(shí)先將螺塞擰到底，再退回1/5～1/2圈，然后用開口銷鎖住調(diào)整螺塞。②安裝轉(zhuǎn)向橫拉桿總成：將轉(zhuǎn)向橫拉桿接頭夾在虎鉗上，裝入上球頭座。把轉(zhuǎn)向橫拉桿總成裝到左、右梯形臂的錐孔內(nèi)，按規(guī)定力矩?cái)Q緊球頭銷螺母，裝好開口銷。①系統(tǒng)壓力檢查。清潔并檢查是否有漏油痕跡。 轉(zhuǎn)向器齒輪齒條的間隙調(diào)整通過圖36中所標(biāo)的調(diào)節(jié)螺釘進(jìn)行調(diào)整。②關(guān)閉發(fā)動(dòng)機(jī)，在轉(zhuǎn)向油罐中添加轉(zhuǎn)向油至規(guī)定高度，滿打轉(zhuǎn)向盤2～3次，若液面下降需補(bǔ)充轉(zhuǎn)向油。②分別用軟管夾夾住通向儲(chǔ)液罐和葉片泵的軟管。⑥拆下轉(zhuǎn)向器固定螺栓，取下動(dòng)力轉(zhuǎn)向器總成。③橡膠防護(hù)套應(yīng)無損壞。漏油一般發(fā)生在管接頭、密封圈、油封等處；齒輪齒條的間隙可通過調(diào)節(jié)螺釘予以調(diào)整。（4）轉(zhuǎn)向盤的轉(zhuǎn)向力和自由行程在規(guī)定范圍內(nèi)。（8）轉(zhuǎn)向輪定位正確?？梢灶A(yù)料，隨著我國(guó)汽車技術(shù)的進(jìn)步，汽車電子新技術(shù)必將會(huì)得到越來越廣泛的應(yīng)用，國(guó)產(chǎn)汽車電動(dòng)轉(zhuǎn)向系統(tǒng)也必將走向成熟。 While the car is a high speed, steering control unit control motor output smaller torque, such drivers in manipulating the steering wheel is more stable. Due to the speed adjustable motor, can instantly shut, pared with hydraulic steering system, it saves engine fuel consumption, improve the economy. Electrohydraulic power steering system although in hydraulic steering system basis of technology has greatly improved, but the existence of hydraulic equipment are still made the system, such as the hard to overe shortings existing oil leakage, not easy installation and maintenance, etc. Although realized the change, but the dynamical characteristics in hydraulic booster system based on electronic control device increased again, making the system structure is plex, cost increases. Because electrohydraulic steering system technology, may realize the mature electroniccontrolled system integration, vehicle as traditional hydraulic steering system to electric power steering system of intermediate technology of transition, in certain time will continue to receive applications and development. electric power steering system (EPAS or EPS) Electric power steering system is the traditional mechanical steering system foundation, increased sensor device, electronic control devices and steering mechanism, etc. Its characteristic is to use electric actuators in different driving conditions for pilot provide appropriate support. System mainly consists of the electronic control unit ECU, torque sensor, the wheel speed sensors, motor, clutch and the steering assembly etc. Electric power steering system working principle is: the pilot control steering, the sensor will pilot role in steering wheel torque signal, speed signal, engine speed signal input ECU, ECU of the input signal calculations, inquires the booster form, determine the size and direction target current, so as to control motor current and the direction, by slowing institutions and clutch motor torque transfer to steering mechanism will be, so as to provide the proper power。s steering data, then through the data bus would signals to the ECU, and getting feedback from steering control system [7] mand. Steering control system is also obtained from steering control agencies, and the steering instructions drivers from steering system obtain wheel situation, thus mand the steering system of sports. Steering system KongZhiChe cycle to need Angle, and will wheel corner and rotational torque feedback to the rest of the system, such as steering control agencies, in order to make drivers get way feeling, the size of the road are according to different conditions can be controlled by steering control system. The steering system has many advantages [8] : (1) the intervene problem to eliminate steering。 (4) can be personalized land suitable for specific driver and driving environment, and steering behavior could be about driving through software to realize。 　　至今，汽車轉(zhuǎn)向系統(tǒng)經(jīng)歷了傳統(tǒng)機(jī)械轉(zhuǎn)向系統(tǒng)、液壓助力轉(zhuǎn)向系統(tǒng)、電液助力轉(zhuǎn)向系統(tǒng)和電動(dòng)助力轉(zhuǎn)向系統(tǒng)4個(gè)發(fā)展階段，未來則可能向線控動(dòng)力轉(zhuǎn)向系統(tǒng)發(fā)展。轉(zhuǎn)向器是把方向盤傳來的轉(zhuǎn)矩按一定傳動(dòng)比放大并輸出的增力裝置,轉(zhuǎn)向器最早采用的是蝸輪蝸