【正文】 nation of theory and practice, in theory under the premise of learning, with a better understanding of the actual content of what they have learned.Keywords: automobile steering system, working principle, failure, maintenance, programs, bining theory and practice緒論汽車轉向系統(tǒng)是用于改變或保持汽車行駛方向的專門機構。汽車轉向系統(tǒng)的功能就是按照駕駛員的意愿控制汽車的行駛方向。就輪式汽車而言,實現汽車轉向的方法是, 駕駛員通過一套專設的機構,使汽車轉向橋(一般是前橋)上的車輪(轉向輪)相對于汽車縱橫線偏轉一定角度。動力轉向系統(tǒng)：借助動力來操縱的轉向系統(tǒng)。圖11向系統(tǒng)結構上圖是一種機械式轉向系統(tǒng)。經轉向器放大后的力矩和減速后的運動傳到轉向橫拉桿，再傳給固定于轉向節(jié)上的轉向節(jié)臂，使轉向節(jié)和它所支承的轉向輪偏轉，從而改變了汽車的行駛方向。 目前較常用的有齒輪齒條式、循環(huán)球曲柄指銷式、蝸桿曲柄指銷式、循環(huán)球齒條齒扇式、蝸桿滾輪式等。轉彎半徑越小，則汽車轉向所需場地就越小。直拉桿的典型結構如圖15在轉向輪偏轉或因懸架彈性變形而相對于車架跳動時，轉向直拉桿與轉向搖臂及轉向節(jié)臂的相對運動都是空間運動，為了不發(fā)生運動干涉，上述三者間的連接都采用球銷。圖16 　2 汽車轉向系統(tǒng)的故障診斷機械轉向系的常見故障部位主要有：轉向盤自由行程、轉向傳動機構連接處、轉向器等。具體原因主要有：①轉向輪輪胎氣壓不足，應按規(guī)定充氣。⑤轉向器缺油或無油，應按規(guī)定添加潤滑油。⑨轉向節(jié)主銷與轉向節(jié)襯套配合過緊或缺油，或轉向節(jié)止推軸承缺油，應予調整或添加潤滑脂等。 故障現象汽車保持直線行駛位置靜止不動時，轉向盤左右轉動的游動角度太大。②轉向盤與轉向軸連接部位松曠，應予調整。⑥轉向節(jié)主銷與襯套磨損后松曠，應予更換。尤其是高速時，轉向輪擺振嚴重，握轉向盤的手有麻木感，甚至在駕駛室可看到汽車車頭晃動。③兩轉向輪的定位不正確，應予調整或更換部件。⑦轉向器在車架上的連接松動，應予緊固。 故障診斷方法以桑塔納乘用車為例，根據轉向輪抖動特征，按照圖22械轉向系轉向輪抖動常見故障原因的診斷流程找出故障部位。動力轉向系的常見故障主要是轉向沉重和轉向噪聲。②油路堵塞或不暢，應予檢修。⑥調節(jié)閥失效，使輸出壓力過低，應予更換或調整。詳見圖23所示動力轉向系轉向沉重助力部分常見故障原因的診斷流程。②轉向泵傳動帶打滑，應予調整或更換。 故障診斷方法轉向時發(fā)出“咔噠”聲，在已排除轉向泵葉片噪聲的情況下，則由轉向泵帶輪出現松動引起。 轉向盤回位不良故障原因主要是：系統(tǒng)內有空氣、壓力限制閥工作不良，控制閥彈簧失效等。）、轉向盤外緣最大轉向切向力（即轉向盤最大轉向力，N）、轉向輪最大轉向角（176。轉向輪定位應該是行駛系的內容，但由于該參數的改變，既可能造成行駛系故障（如輪胎異常磨損），也可能造成轉向系故障（如轉向沉重），因此轉向輪定位參數通常也作為轉向系的診斷參數。如果轉向太輕，又可能導致駕駛員路感太弱或汽車“發(fā)飄”，同樣不利于行車安全。 安裝將轉向參數測量儀對準被測轉向盤中心，調整好三只活動卡爪長度，與轉向盤牢固連接。轉向力的檢測可按轉向輕便性實驗方法進行，一般有原地轉向力實驗、低速大轉角（“8”字行駛）轉向力實驗、彎道轉向力實驗等，可參照有關國家標準的規(guī)定進行檢測。轉向盤自由轉動量是一個綜合診斷參數，當其超過規(guī)定的值時，說明從轉向盤至轉向輪的傳動鏈中有—處或幾處的配合出現松曠。刻度盤通過磁力座吸附在駕駛室儀表盤或轉向管柱上，指針則固定在轉向盤的周緣上；也可將指針通過磁力座固定在儀表板或轉向管柱上，而刻度盤固定在轉向盤周緣上。 檢查轉向傳動軸萬向節(jié)有無松動、磨損，視情況予以更換。（2）檢查轉向器外殼是否破裂，視情況焊補或更換。15176。（6）潤滑?，F以該車為例，闡述這類轉向器的拆卸、檢修與裝配。③拆卸防塵套鎖簧和防塵罩管箍，拆下轉向器齒條防塵罩。拉出齒條時，應使齒條朝向殼體側面再拔出，以防劃傷襯套；不允許旋轉齒條。用專用工具拆下軸上彈性擋圈，再用專用工具拆卸軸承。②檢查軸承是否松曠，若磨損嚴重應更換新軸承。③裝配轉向小齒輪。注意不要劃傷齒條齒套。前后移動轉向齒條約15次，使齒條處于穩(wěn)定狀態(tài)，然后繼續(xù)擰緊壓簧調整螺塞，如果沒有達到規(guī)定值，則應重復以上操作。m。初步擰緊鎖緊螺母，在檢查調整好前輪前束后，最后擰緊鎖緊螺母。（3）緊固和潤滑。④拆下轉向橫拉桿總成并分解。④球頭銷螺紋應無損傷，否則應更換；球頭銷彈簧不應有彈力減弱或折斷現象，否則應更換。將球頭銷的球頭涂以潤滑脂，從轉向直拉桿側面的大孔中裝入。將轉向直拉桿的兩個球頭銷分別裝到轉向搖臂和轉向節(jié)上臂錐孔內，按規(guī)定力矩擰緊球頭銷螺母，裝好開口銷。分別將左、右橫拉桿接頭總成裝到橫拉桿的兩端，并擰緊左右橫拉桿接頭的4個螺栓。②檢查油液是否有起泡或乳化現象。如圖34，起動發(fā)動機并怠速運轉，滿方向轉動轉向盤數次，將壓力表閥門關閉（不超過5s），～ Map。 測量轉向盤上的轉向力超過40N應予以檢查維修，同時，轉向盤自由行程應在規(guī)定范圍內。同時起動發(fā)動機怠速運轉，左右轉動轉向盤。 動力轉向系的修理以寶來乘用車為例： 拆卸①拆下萬向節(jié)，將萬向節(jié)從轉向器中拉出。⑤密封好從轉向器上取下的軟管，并對轉向器上露出的螺紋進行保護。②密封襯墊等經過拆卸后應更換新件。此種轉向器的常見損壞是漏油和齒輪齒條間隙過大。（3）轉向輪具有自動回正能力。（7）橫、直拉桿不得拼焊。隨著未來汽車市場的快速發(fā)展和汽車電子價值含量的迅速提高，我國汽車電動轉向系統(tǒng)將形成巨大經濟規(guī)模效應。t change the steering response characteristics are unable to control and transmission in the process of steering cannot with speed and lateral acceleration and other parameters of the changes, the pilot must pensate for car before in turn the steering response characteristics of certain operating pensation, such virtually increased the mental and physical burdens driver [2]. hydraulic steering system Hydraulic steering system (HPS) is the traditional mechanical steering system basis with a set of additional hydraulic booster, generally by oil pump, vshaped belt wheel, oil injection equipment, power devices and control valves etc. It with hydraulic oil pump is the power, through the movement to promote produced mechanical redirector work. Because the system through hydraulic works used to promote the traditional mechanical steering mechanism of steering movement so as to reduce the labor intensity, a driver in a certain extent, solve the traditional mechanical steering system caused because of transmission ratio fixed to light and sensitive the contradiction between. But, this kind of power steering system is driven by the steering wheel rotates the hydraulic system directly change torsion bar is the channel area to provide oiling the instrumentality of variable. Namely the discretion of size and speed boost have no relation with steering Angle, only concerned. Steering dish of greater perspective, turn the instrumentality of hydraulic systems provide is bigger also. Meanwhile, this system has the following weakness: (1) no matter car turn not to, as long as the engine and hydraulic motor drive ZhuLiBeng will work under the energy, the extra consumption engine. (2) the steering characteristics not adjusted, highspeed and same speed dynamical characteristics. In lowspeed steering need bigger boost, often for engine speed and low power poor effect, while in highspeed steering need smaller, will boost for engine speed high and power function big, bring about steering too sensitive, that the car manipulation stability bees poor. (3) the inherent hydraulic system of the hydraulic oil leakage problems and steering noise makes steering fort, meantime, dramatically reduced environmental pollution. Because of hydraulic steering system reliable work, mature technology, can provide the big steering and has been widely used. electrohydraulic power steering system Electrohydraulic power steering system at work steering characteristics can be changed. It basically has two kinds: electric hydraulic steering system (ECHPS) and electric hydraulic steering system (EHPS). Now automotive applications is the largest electric hydraulic booster turn from system. electronic control hydraulic power steering system Electric hydraulic steering system (ECHPS) in hydraulic steering system is based on the liquid flow rate increased control solenoid valves, torque sensor, the wheel speed sensors and steering control unit etc ponents. Ideally, car in spin to try to deft, request when in cars to different speed operation, which can realtime provide corresponding steering to overe the running speed to make drivers to resistance to manipulate the steering wheel can both lightweight, and have enough way feeling. In steering process, through the torque sensor, speed sensor etc sensing device will shift to rate, speed transfer to parameters such as steering control unit. After decoding, c