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中文譯文
汽車電動助力轉向系統(tǒng)的研究
隨著汽車電子技術的迅猛發(fā)展,人們對汽車轉向操縱性能的要求也日益提高。汽車轉向系統(tǒng)已從傳統(tǒng)機械轉向、液壓助力轉向(Hydraulic Power Steering ,簡稱HPS) 電控液壓助力轉向( Electric Hydraulic Power Steering , 簡稱EHPS) , 發(fā)展到電動助力轉向系統(tǒng)(Electric Power Steering ,簡稱EPS) ,最終還將過渡到線控轉向系統(tǒng)(Steer By Wire ,簡稱SBW)。
機械轉向系統(tǒng)是指以駕駛員的體力作為轉向能源,其中所有傳力件都是機械的,汽車的轉向運動是由駕駛員操縱方向盤,通過轉向器和一系列的桿件傳遞到轉向車輪而實現(xiàn)的。機械轉向系由轉向操縱機構、轉向器和轉向傳動機械3大部分組成。
通常根據(jù)機械式轉向器形式可以分為:齒輪齒條式、循環(huán)球式、蝸桿滾輪式、蝸桿指銷式。應用最廣的兩種是齒輪齒條式和循環(huán)球式(用于需要較大的轉向力時) 。在循環(huán)球式轉向器中,輸入轉向圈與輸出的轉向搖臂擺角是成正比的;在齒輪齒條式轉向器中,輸入轉向圈數(shù)與輸出的齒條位移是成正比的。循環(huán)球式轉向器由于是滾動摩擦形式,因而正傳動效率很高,操作方便且使用壽命長,而且承載能力強,故廣泛應用于載貨汽車上。齒輪齒條式轉向器與循環(huán)球式相比,最大特點是剛性大,結構緊湊重量輕,且成本低。由于這種方式容易由車輪將反作用力傳至轉向盤,所以具有對路面狀態(tài)反應靈敏的優(yōu)點,但同時也容易產(chǎn)生打手和擺振等現(xiàn)象,且其承載效率相對較弱,故主要應用于小汽車及輕型貨車上,目前大部分低端轎車采用的就是齒輪齒條式機械轉向系統(tǒng)。
隨著車輛載重的增加以及人們對車輛操縱性能要求的提高,簡單的機械式轉向系統(tǒng)已經(jīng)無法滿足需要,動力轉向系統(tǒng)應運而生,它能在駕駛員轉動方向盤的同時提供助力,動力轉向系統(tǒng)分為液壓轉向系統(tǒng)和電動轉向系統(tǒng)2種。其中液壓轉向系統(tǒng)是目前使用最為廣泛的轉向系統(tǒng)。
液壓轉向系統(tǒng)在機械系統(tǒng)的基礎上增加了液壓系統(tǒng),包括液壓泵、V 形帶輪、油管、供油裝置、助力裝置和控制閥。它借助于汽車發(fā)動機的動力驅動液壓泵、空氣壓縮機和發(fā)電機等,以液力、氣力或電力增大駕駛員操縱前輪轉向的力量,使駕駛員可以輕便靈活地操縱汽車轉向,減輕了勞動強度,提高了行駛安全性。
液壓助力轉向系統(tǒng)從發(fā)明到現(xiàn)在已經(jīng)有了大約半個世紀的歷史,可以說是一種較為完善的系統(tǒng),由于其工作可靠、技術成熟至今仍被廣泛應用。它由液壓泵作為動力源,經(jīng)油管道控制閥向動力液壓缸供油,通過活塞桿帶動轉向機構動作,可通過改變缸徑及油壓的大小來改變助力的大小,由此達到轉向助力的作用。傳統(tǒng)液壓式動力轉向系統(tǒng)一般按液流的形式可以分為:常流式和常壓式2 種類型,也可根據(jù)控制閥形式分為轉閥式和滑閥式。
隨著液壓動力轉向系統(tǒng)在汽車上的日益普及,人們對操作時的輕便性和路感的要求也日益提高,然而液壓動力轉向系統(tǒng)卻存在許多的缺點: ①由于其本身的結構決定了其無法保證車輛在任何工況下轉動轉向盤時,都有較理想的操縱穩(wěn)定性,即無法同時保證低速時的轉向輕便性和高速時的操縱穩(wěn)定性; ②汽車的轉向特性受駕駛員駕駛技術的影響嚴重; ③轉向傳動比固定,使汽車轉向響應特性隨車速、側向加速度等變化而變化,駕駛員必須提前針對汽車轉向特性幅值和相位的變化進行一定的操作補償,從而控制汽車按其意愿行駛。這樣增加了駕駛員的操縱負擔,也使汽車轉向行駛中存在不安全隱患;而此后出現(xiàn)了電控液壓助力系統(tǒng),它在傳統(tǒng)的液壓動力轉向系統(tǒng)的基礎上增加速度傳感器,使汽車能夠隨著車速的變化自動調節(jié)操縱力的大小,在一定程度上緩和了傳統(tǒng)的液壓轉向系統(tǒng)存在的問題。
目前我國生產(chǎn)的商用車和轎車上采用的大多是電控液壓助力轉向系統(tǒng),它是比較成熟和應用廣泛的轉向系統(tǒng)。盡管電控液壓助力裝置從一定程度上緩解了傳統(tǒng)的液壓轉向中輕便性和路感之間的矛盾,然而它還是沒有從根本上解決HPS 系統(tǒng)存在的不足,隨著汽車微電子技術的發(fā)展,汽車燃油節(jié)能的要求以及全球性倡導環(huán)保,其在布置、安裝、密封性、操縱靈敏度、能量消耗、磨損與噪聲等方面的不足已越來越明顯,轉向系統(tǒng)向著電動助力轉向系統(tǒng)發(fā)展。
電動助力轉向系統(tǒng)是現(xiàn)在汽車轉向系統(tǒng)的發(fā)展方向,其工作原理是:EPS 系統(tǒng)的ECU 對來自轉向盤轉矩傳感器和車速傳感器的信號進行分析處理后,控制電機產(chǎn)生適當?shù)闹D矩,協(xié)助駕駛員完成轉向操作。近幾年來,隨著電子技術的發(fā)展,大幅度降低EPS的成本已成為可能,日本的大發(fā)汽車公司、三菱汽車公司、本田汽車公司、美國的Delphi 汽車系統(tǒng)公司、TRW公司及德國的ZF 公司都相繼研制出EPS。Mercedes2Benz 和Siemens Automotive 兩大公司共同投資6500萬英鎊用于開發(fā)EPS ,目標是到2002 年裝車,年產(chǎn)300 萬套,成為全球EPS 制造商。到目前為止,EPS 系統(tǒng)在輕微型轎車、廂式車上得到廣泛的應用,并且每年以300 萬臺的速度發(fā)展。
.轉向是一個專業(yè)術語,適用于采集部件,聯(lián)系等,其中允許一艘(艦船)或汽車(轎車)按照預期的方向行駛. 一個例外的情況是鐵路運輸由路軌組合在一起鐵路道岔提供轉向功能。
許多現(xiàn)代轎車使用齒輪齒條式轉向器,在方向盤末端有轉動齒輪;該齒輪帶動齒條移動,它是一種線性的齒輪緊密配合,從一邊到一邊。這種運動把轉矩通過轉向橫拉桿和一種叫做轉向節(jié)臂的短形臂傳遞給轉向輪的主銷。
以前的設計往往采用循環(huán)球式轉向器,而這種轉向器仍然應用在卡車和多用途車輛。這是一種老式的螺母和齒扇設計，該轉向管柱轉動大螺絲("蝸輪"),它與一個齒扇齒輪嚙合,當蝸輪轉動時，齒扇也隨之轉動，一個安裝在齒扇軸上且與轉向聯(lián)動有關的搖臂帶動轉向節(jié)臂 ,從而使車輪轉動. 循環(huán)球式轉向器通過安裝滾珠減少螺母和螺桿之間的摩擦;兩根導管和螺母內的螺旋管狀通道組合成兩條各自獨立的封閉的鋼球“流到”。
齒輪齒條式轉向器設計具有很大程度的反饋和直接轉向"路感";它也通常不會有任何反彈,或呆滯。缺點是,它是不可調的,因此當它磨損唯一的解決辦法更換。
循環(huán)球式轉向器的優(yōu)點是機械優(yōu)勢,因此,它被使用在較大較重的車輛,而齒輪齒條式原本僅限于較小和較輕;由于幾乎普遍采用動力轉向系統(tǒng),不過,這已不再是一個重要的優(yōu)勢,導致越來越多地在新型汽車應用齒輪齒條式轉向器。 循環(huán)球式轉向器設計在中心也有明顯的沖擊,或"死點"。凡一分鐘交替方向盤出不來并不移動轉向機構;這是很容易可調螺桿的端部來減少磨損,但它并不能完全消除或機制開始磨損很快。 這項設計目前仍在使用中,在卡車和其他大型車輛,也應用于迅速轉向,路感與穩(wěn)健性,可維護性,和機械的優(yōu)勢相比不太重要的場合。 較小程度的反饋,這樣的設計也有時是一種優(yōu)點;當前輪碰撞時，使用齒輪齒條轉向的司機只有自己的大拇指受傷,造成方向盤揭開一邊突然(因為駕駛教練告訴學生把自己的大拇指在前面的方向盤,而非放在左右的內邊緣).這種效果在像卡車一樣的重型汽車更為明顯;循環(huán)球式轉向防止這種程度的反饋,只是因為它可以在正常情況下防止可取反饋。
轉向連鎖連接轉向器和車輪通常符合一個阿克曼轉向幾何的變化,它交代了一個事實:當轉向是,內輪轉過的半徑比外輪小得多，因此適合駕駛的直路,是不適合曲折。
由于車輛已成為較重而改用前輪驅動,為了扭轉方向盤，通常的,主要的是體力。為了解決這一問題,汽車業(yè)發(fā)展的動力轉向系統(tǒng)。 有兩種類型的助力轉向系統(tǒng)-液壓和電氣/電子。 T還有一種液壓-電動混合系統(tǒng)。
液壓助力轉向系統(tǒng)(hps)利用油壓供應的一個發(fā)動機驅動泵,以協(xié)助將方向盤轉轉動。 電動助力轉向系統(tǒng)(EPS)方式,是較有效率的液壓助力轉向系統(tǒng),由于電動助力轉向汽車只需要提供協(xié)助時,方向盤被轉動,而液壓泵必須不斷運行。 在EPS的幫助下是很容易調節(jié)車型,最高車速,甚至駕駛的喜好。 另外一個好處是,通過泄漏和處置動力轉向液消除對環(huán)境構成危險 。
A動力轉向的分支是速度可調轉向而轉向是大量輔助以低速行駛,稍微協(xié)助高速。 汽車制造商認為,當要停車時駕駛人可能需要做出大量轉向投入，但當時高速行駛時則不然。第一輛有這特點的汽車,是雪鐵龍與其diravi，雖然改變了現(xiàn)代汽車轉向系統(tǒng)資金的投入，但它改變了定心凸輪的壓力，使得方向盤盡力去回到原來的位置?，F(xiàn)代速度可調式動力轉向系統(tǒng),當速度增長時減少了活塞的壓力 ,給予更直接的感受。這一特點在所有新車正逐漸成為司空見慣。
四輪轉向(或全輪轉向)是一種系統(tǒng),當高速行駛時能增加車輛穩(wěn)定型，而在低速行駛時可以減小轉彎半徑。
大多數(shù)的四輪轉向系統(tǒng),后輪轉向通過單片機和驅動器實現(xiàn)。 后輪一般不能反過來,有幾個系統(tǒng),包括Delphi的quadrasteer，該系統(tǒng)在本田的生產(chǎn)前線，當前輪低速時，允許后輪在相反方向轉向。這使得車輛轉彎半徑較小,有時應用于大型卡車車輛及掛車。
電子動力轉向系統(tǒng)
圖1
電子動力轉向系統(tǒng)的工作原理
電子動力轉向系統(tǒng)是通過一個電動機來驅動動力方向盤液壓泵或直接驅動轉向聯(lián)動裝置。
電子動力轉向的功能由于不依賴于發(fā)動機轉速，所以能節(jié)省能源
電子動力轉向系統(tǒng)是這樣運行的
傳統(tǒng)的動力方向盤系統(tǒng)使用一條引擎輔助傳送帶駕駛泵浦，提供操作在動力方向盤齒輪或作動器的一個活塞協(xié)助司機的被加壓的流體。在電動液壓的指點，一個電子動力方向盤概念使用一臺電動機駕駛的一個高效率泵浦。 泵浦速度是由一個電控制器調控的變化泵浦壓力和流程，提供被剪裁的指點努力為不同的駕駛的情況。 泵浦可以跑在低速或關閉提供節(jié)能在大多時間在多數(shù)世界市場上)直向前的駕駛期間(直接電指點使用一臺電動機附加指點機架通過齒輪機構(沒有泵浦或流體)。 各種各樣的馬達類型和齒輪驅動是可能的。 微處理器控制指點動力學和司機努力。 輸入包括車速和指點、輪子扭矩，角位和轉動率。
工作運行時的具體細節(jié)：
A “指點傳感器”位于它進入傳動箱住房的輸入軸。 指點傳感器實際上是在一個的二個傳感器： 那“扭矩的傳感器”轉換指點扭矩輸入和它的方向成電壓信號，并且那“自轉的傳感器”轉換轉動速度和方向成電壓信號。 分享同一套住房的“接口”電路轉換從扭矩傳感器和自轉傳感器的信號成控制電子學可能處理的信號。從指點傳感器的輸入由那微處理器的控制單元消化也監(jiān)測從車速傳感器的輸入。 傳感器輸入然后被比較確定多少機械化根據(jù)一張被預編程序的“力量地圖”需要在控制單元的記憶。 控制單元然后派出適當?shù)拿顚θ缓蠊┙o電動機以潮流的“電源裝置”。 馬達推擠機架在右邊或左根據(jù)哪個方式電壓流動(扭轉潮流扭轉方向馬達旋轉)。 增加潮流對馬達增加功率協(xié)助。系統(tǒng)有三種操作方式： 左邊或右邊機械化提供以回應從指點扭矩和自轉傳感器的輸入的輸入的“正?！笨刂品绞? 被用于在完成輪以后協(xié)助指點回歸的“回歸”控制方式; 并且改變與車速改進路感受和挫傷傭金的“更加潮濕的”控制方式。如果方向盤被轉動，并且舉行在充分鎖位置和指點協(xié)助到達最大值，控制單元使潮流降低到電動機防止也許損壞馬達的超載情況。 控制單元也被設計保護馬達以防止電壓浪涌免受一個有毛病的交流發(fā)電機或充電的問題。
電子轉向控制單位有能力在自我診斷的缺點通過監(jiān)測系統(tǒng)輸入和產(chǎn)品和電動機的激勵電流上。 如果問題發(fā)生，控制單元通過開動在電源裝置的一個故障自動保險的中轉關閉系統(tǒng)。 這消滅所有機械化，造成系統(tǒng)恢復回到手工指點。 破折號EPS警告燈也被闡明警告司機。 要診斷問題，技術員跳服務檢查連接器的終端并且讀出問題代碼。
圖 2
電子動力方向盤機制
當前發(fā)明與提供的供給動力的援助一電子功率驅動器馬達關連給車操縱機構。根據(jù)當前發(fā)明的一個方面，那里為提供供給動力的援助提供一個電子功率驅動器機制給有車的操縱機構一名手動地可旋轉的成員為操作操縱機構、傳動機構包括可行扭矩的傳感器感覺手動地被申請于可旋轉的成員的扭矩，一個電子功率驅動器馬達操縱著被連接到可旋轉的成員和安排控制主驅動電動機自轉速度和方向以回應從扭矩傳感器收到的信號的控制器，扭矩傳感器包括為與可旋轉的成員的連接適應的傳感器軸形成引伸因此，以便扭矩通過前述傳感器軸被傳送，當時 可旋轉的成員被轉動，并且應變儀在導致的信號傳感器軸手動地登上表示通過前述軸被傳送的相當數(shù)量扭矩。
圖3
傳感器軸不旋轉更好地登上在一個軸向末端在第一名聯(lián)結成員和不旋轉地登上在它的相反軸向末端在第二名聯(lián)結成員，第一和第二名聯(lián)結成員相互允諾允許有限的自轉之間連接，以便在一個被預先決定的極限之下的扭矩由僅傳感器軸傳送，并且，以便在前述被預先決定的極限之上的扭矩通過第一和第二名聯(lián)結成員被傳送。
更適宜地安排第一和第二名聯(lián)結成員作為操縱的連接的第一和第二個部分的一座橋梁互相的旋轉式成員。合適的傳感器軸是通常在多數(shù)的長方形橫斷面它的長度中。應變儀包括一個或更多的適應地看見了諧振器綁到傳感器軸上。好的馬達操縱的被連接到可旋轉的成員通過傳動器。馬達更好地包括一個工具箱和同心地被安排相對可旋轉的成員。當前發(fā)明的Various方面此后將描述，關于伴隨的圖畫， ：圖1是一個車操縱機構的一個圖表看法包括一個電子功率驅動器機制根據(jù)當前發(fā)明，圖 2是說明在圖顯示的傳動機構的各種各樣的組分的之間流程圖互作用1上，圖 3是一個軸截面通過在圖顯示的傳動機構1，圖4上是一張截面圖被采取沿著線IV-IV在表3，圖5是在圖顯示的輸入推進聯(lián)結的一張更加詳細的分解圖3上，和圖 6是顯示在表3.的傳動器的一張更加詳細的分解圖。 圖1的最初Referring，那里顯示一個車操縱機構10操縱的被連接到一個對易操縱的路輪子12。這個顯示的操縱機構包括一個齒條和齒輪匯編14被連接到路輪子12通過聯(lián)接15。 鳥翼末端(沒顯示)匯編14可旋轉地駕駛一名手動地可旋轉的成員以駕駛桿18的形式哪些由方向盤19手動地轉動。這個駕駛桿18包括包括一臺電主驅動電動機的一個電力的傳動機構30 (沒顯示在駕駛的鳥翼末端圖1)上以回應在駕駛桿18的扭矩裝貨為了為機械人員提供力量援助，當轉動方向盤19時。如概要地被說明在表2，電力的傳動機構包括測量駕駛桿申請的扭矩18，當駕駛鳥翼末端時并且提供信號給控制器40的扭矩傳感器20。 控制器40被連接到主驅動電動機50并且控制電流被提供給馬達50控制馬達50和它的自轉的方向扭矩引起的相當數(shù)量。馬達50 操縱的更適宜地被連接到駕駛桿18通過工具箱60，更適宜地一個周轉齒輪箱子和傳動器70。 在一定條件下傳動器70在正常運行時更適宜地永久地接合并且是有效的隔絕從馬達50的驅動使鳥翼末端通過傳動機構30手動地被駕駛。 這是使機制的安全特點起作用在試圖的馬達50情形下駕駛太快速的駕駛桿并且/或者在錯誤的方向或在案件 電動機和工具箱占領了。
扭矩傳感器20更適宜地是一個匯編包括在扭矩應用達到的傳感器軸登上應變儀能夠準確測量張力在一個被預先決定的范圍之內的一個短的傳感器軸。被測量扭矩的被預先決定的范圍是0-lONm; 更好是關于l-5Nm。被測量的扭矩的范圍更好地對應于大約0-1000微指令，并且傳感器軸的建筑更好被選擇這樣5Nm扭矩比在軸的2°導致較少的轉彎，少于1 °。好的應變儀是鋸諧振器，在WO91/13832被描述的一臺適當?shù)匿徶C振器。 類似在圖顯示的那WO91/13832 3上更好地運用配置，二看見諧振器被安排在對軸軸的45°和在90°對互相。諧振器經(jīng)營與在200-400 MHz之間共鳴頻率和被安排導致信號到控制器1 MHz 40 ± 500 KHz根據(jù)傳感器軸的自轉方向的自我調節(jié)。 因此，當傳感器軸不被扭轉的歸結于缺乏扭矩時，它導致一個1 MHz信號。當它導致在1.0到1.5 MHz之間的一個信號的傳感器軸在一個方向被扭轉。 當傳感器軸在相反方向時被扭轉它導致在1.0到0.5 MHz之間的一個信號。 因而同樣傳感器能導致信號表示程度扭矩并且傳感器軸的自轉的方向。好的馬達扭矩引起的相當數(shù)量以回應在0-10Nm之間被測量的扭矩是0-40Nm，并且為在l-5Nm之間被測量的扭矩是0-25Nm。反饋電路提供自我調節(jié)，借以馬達使用的電流由控制器40測量并且比較保證馬達在正確方向運行并且提供期望功率協(xié)助。 控制器更好地行動使被測量的扭矩降低到零和如此控制馬達增加它的扭矩產(chǎn)品減少被測量的扭矩。 (沒顯示)更適宜地提供車速傳感器哪些寄發(fā)一個信號表示車速到控制器。 控制器使用這個信號修改程度力量協(xié)助提供以回應被測量的扭矩。將提供在低車速最大力量協(xié)助的，因而，并且將提供高車速極小的力量協(xié)助。更適宜地是邏輯順序器有一個現(xiàn)場可編程序的門數(shù)組例如XC 4005如Xilinx供應這個控制器。 這樣控制器不依靠軟件和，因此能更起作用可靠地在汽車車環(huán)境里。 被想象也許使用有邏輯的序列一個現(xiàn)場可編程序的列陣。 一個電力傳動機構10的A具體建筑在表3.被說明。
電子動力轉向系統(tǒng)（英文簡稱EPS）， 與液壓動力轉向系統(tǒng)（HPS）相比，EPS具有很多優(yōu)點。即EPS的優(yōu)勢在于：
1）效率高。HPS效率很低，一般為60%~70%；而EPS與電機連接，效率高，有的可高達90%以上。
2）耗能少。汽車在實際行駛過程中，處于轉向的時間約占行駛時間的5%，對于HPS系統(tǒng)，發(fā)動機運轉時，油泵始終處于工作狀態(tài)，油液一直在管路中循環(huán)，從而使汽車燃油消耗率增加4%~6%；而EPS僅在需要時供能，使汽車的燃油消耗率僅增加0.5%左右。
3）“路感“好。由于EPS內部采用剛性連接，系統(tǒng)的滯后特性可以通過軟件加以控制，且可以根據(jù)駕駛員的操作習慣進行調整。
4）回正性好。EPS結構簡單內部阻力小，回正性好，從而可得到最佳的轉向回正特性，改善汽車操縱穩(wěn)定性。
5）對環(huán)境污染少。HPS液壓回路中有液壓軟管和接頭，存在油液泄露問題，而且液壓軟管不可回收，對環(huán)境有有一定污染；而EPS對環(huán)境幾乎沒有污染。
6）可以獨立于發(fā)動機工作。EPS以電池為動力元件，只要電池電量充足，不論發(fā)動機出于何種狀態(tài)，都可以產(chǎn)生助力作用。
7）應有范圍廣。
8）裝配性好易于布置。
現(xiàn)在，動力轉向系統(tǒng)已成為一些轎車的標準設置，全世界約有一半的轎車采用動力轉向。隨著汽車電子技術的發(fā)展，目前一些轎車已經(jīng)使用電動助力轉向器，使汽車的經(jīng)濟性、動力性和機動性都有所提高。電動助力轉向裝置是汽車上一種新的助力轉向系統(tǒng)裝置,近年來在國內外發(fā)展迅速,由于它采用了可編程電子控制裝置,在帶來靈活性的同時也存在著安全隱患.在分析這種產(chǎn)品特殊性的基礎上,筆者結合電子控制裝置的特點,指出了事關安全性的因素,提出了處理安全性的措施,并討論了幾個事關安全性的具體問題.研究結果表明:現(xiàn)有標準不能夠滿足電動助力轉向裝置安全性的需要;并提出了對電動助力轉向裝置進行安全性測評的思想.研究工作對電動助力轉向裝置的開發(fā)以及評價具有參考意義。
英文原文
The auto electric power steering system research
Along with automobile electronic technology swift and violent development, the people also day by day enhance to the motor turning handling quality request. The motor turning system hanged, the hydraulic pressure boost from the traditional machinery changes (Hydraulic Power Steering, is called HPS), the electrically controlled hydraulic pressure boost changes (Electronic Hydraulic Power Steering, is called EHPS), develops the electrically operated boost steering system (Electronic Power Steering, is called EPS), finally also will transit to the line controls the steering system (Steer By Wire, will be called SBW).
The machinery steering system is refers by pilot's physical strength achievement changes the energy, in which all power transmission all is mechanical, the automobile changes the movement is operates the steering wheel by the pilot, transmits through the diverter and a series of members changes the wheel to realize. The mechanical steering system by changes the control mechanism, the diverter and major part changes the gearing 3 to be composed.
Usually may divide into according to the mechanical diverter form: The gear rack type, follows round the world -like, the worm bearing adjuster hoop type, the worm bearing adjuster refers sells the type. Is the gear rack type and follows using the broadest two kinds round the world -like (uses in needing time big steering force).In follows round the world -like in the diverter, the input changes the circle and the output steering arm pivot angle is proportional; In the gear rack type diverter, the input changes the turn and the output rack displacement is proportional. Follows round the world -like the diverter because is the rolling friction form, thus the transmission efficiency is very high, the ease of operation also the service life are long, moreover bearing capacity, therefore widely applies on the truck. The gear rack type diverter with follows round the world -like compares, the most major characteristic is the rigidity is big, the structure compact weight is light, also the cost is low. Because this way passes on easily by the wheel the reacting force to the steering wheel, therefore has to the pavement behavior response keen merit, but simultaneously also easy to have phenomena and so on goon and oscillation, also its load bearing efficiency relative weak, therefore mainly applies on the compact car and the pickup truck, at present the majority of low end passenger vehicle uses is the gear rack type machinery steering system.
Along with the vehicles carrying capacity increase as well as the people to the vehicles handling quality request enhancement, the simple mechanical type steering system were already unable to meet the needs, the power steering system arise at the historic moment, it could rotate the steering wheel while the pilot to provide the boost, the power steering system divides into the hydraulic pressure steering system and the electrically operated steering system 2kinds.Hydraulic pressure steering system is at present uses the most widespread steering system.
The hydraulic pressure steering system increased the hydraulic system in the mechanical system foundation, including hydraulic pump, V shape band pulley, drill tubing, feed installment, boost installment and control valve. It with the aid of in the motor car engine power actuation hydraulic pump, the air compressor and the generator and so on, by the fluid strength, the physical strength or the electric power increases the pilot to operate the strength which the front wheel changes, enables the pilot to be possible nimbly to operate motor turning facilely, reduced the labor intensity, enhanced the travel security.
The hydraulic pressure boost steering system from invented already had about half century history to the present, might say was one kind of more perfect system, because its work reliable, the technology mature still widely is applied until now. It takes the power supply by the hydraulic pump, after oil pipe-line control valves to power hydraulic cylinder feed, through the connecting rod impetus rotation gear movement, may changes the boost through the change cylinder bore and the flowing tubing head pressure size the size, from this achieved changes the boost the function. The traditional hydraulic pressure type power steering system may divide into generally according to the liquid flow form: Ordinary flow type and atmospheric pressure type 2 kind of types, also may divide into according to the control valve form transfers the valve type and the slide-valve type.
Along with hydraulic pressure power steering system on automobile daily popularization, the people to operates when the portability and the road feeling request also day by day enhance, however the hydraulic pressure power steering system has many shortcomings actually: ①Because its itself structure had decided it is unable to guarantee vehicles rotates the steering wheel when any operating mode, all has the ideal operation stability, namely is unable simultaneously to guarantee time the low speed changes the portability and the high speed time operation stability;②The automobile changes the characteristic to drive the pilot technical the influence to be serious; ③The steering ratio is fixed, causes the motor turning response characteristic along with changes and so on vehicle speed, transverse acceleration to change, the pilot must aim at the motor turning characteristic peak-to-peak value and the phase change ahead of time carries on certain operation compensation, thus controls the automobile according to its wish travel. Like this increased pilot's operation burden, also causes in the motor turning travel not to have the security hidden danger; But hereafter appeared the electrically controlled hydraulic booster system, it increases the velocity generator in the traditional hydraulic pressure power steering system foundation, enables the automobile along with the vehicle speed change automatic control force size, has to a certain extent relaxed the traditional hydraulic pressure steering system existence question.
At present our country produces on the commercial vehicle and the passenger vehicle uses mostly is the electrically controlled hydraulic pressure boost steering system, it is quite mature and the application widespread steering system. Although the electrically controlled hydraulic servo alleviated the traditional hydraulic pressure from certain degree to change between the portability and the road feeling contradiction, however it did not have fundamentally to solve the HPS system existence insufficiency, along with automobile microelectronic technology development, automobile fuel oil energy conservation request as well as global initiative environmental protection, it in aspect and so on arrangement, installment, leak-proof quality, control sensitivity, energy consumption, attrition and noise insufficiencies already more and more obvious, the steering system turned towards the electrically operated boost steering system development.
The electrically operated boost steering system is the present motor turning system development direction, its principle of work is: EPS system ECU after comes from the steering wheel torque sensor and the vehicle speed sensor signal carries on analysis processing, controls the electrical machinery to have the suitable boost torque, assists the pilot to complete changes the operation. In the last few years, along with the electronic technology development, reduces EPS the cost to become large scale possibly, Japan sends the car company, Mitsubishi Car company, this field car company, US's Delphi automobile system company, TRW Corporation and Germany's ZF Corporation greatly all one after another develops EPS.Mercedes2Benz Siemens Automotive Two big companies invested 65,000,000 pounds to use in developing EPS, the goal are together load a car to 2002, yearly produce 300 ten thousand sets, became the global EPS manufacturer. So far, the EPS system in the slight passenger vehicle, on the theater box type vehicle obtains the widespread application, and every year by 300 ten thousand speed development.
Steering is the term applied to the collection of components, linkages, etc. which allow for a vessel (ship, boat) or vehicle (car) to follow the desired course. An exception is the case of rail transport by which rail tracks combined together with railroad switches provide the steering function.
The most conventional steering arrangement is to turn the front wheels using a hand–operated steering wheel which is positioned in front of the driver, via the steering column, which may contain universal joints to allow it to deviate somewhat from a straight line. Other arrangements are sometimes found on different types of vehicles, for example, a tiller or rear–wheel steering. Tracked vehicles such as tanks usually employ differential steering — that is, the tracks are made to move at different speeds or even in opposite directions to bring about a change of course.
Many modern cars use rack and pinion steering mechanisms, where the steering wheel turns the pinion gear; the pinion moves the rack, which is a sort of linear gear which meshes with the pinion, from side to side. This motion applies steering torque to the kingpins of the steered wheels via tie rods and a short lever arm called the steering arm.
Older designs often use the recirculating ball mechanism, which is still found on trucks and utility vehicles. This is a variation on the older worm and sector design; the steering column turns a large screw (the "worm gear") which meshes with a sector of a gear, causing it to rotate about its axis as the worm gear is turned; an arm attached to the axis of the sector moves the pitman arm, which is connected to the steering linkage and thus steers the wheels. The recirculating ball version of this apparatus reduces the considerable friction by placing large ball bearings between the teeth of the worm and those of the screw; at either end of the apparatus the balls exit from between the two pieces into a channel internal to the box which connects them with the other end of the apparatus, thus they are "recirculated".
The rack and pinion design has the advantages of a large degree of feedback and direct steering "feel"; it also does not normally have any backlash, or slack. A disadvantage is that it is not adjustable, so that when it does wear and develop lash, the only cure is replacement.
The recirculating ball mechanism has the advantage of a much greater mechanical advantage, so that it was found on larger, heavier vehicles while the rack and pinion was originally limited to smaller and lighter ones; due to the almost universal adoption of power steering, however, this is no longer an important advantage, leading to the increasing use of rack and pinion on newer cars. The recirculating ball design also has a perceptible lash, or "dead spot" on center, where a minute turn of the steering wheel in either direction does not move the steering apparatus; this is easily adjustable via a screw on the end of the steering box to account for wear, but it cannot be entirely eliminated or the mechanism begins to wear very rapidly. This design is still in use in trucks and other large vehicles, where rapidity of steering and direct feel are less important than robustness, maintainability, and mechanical advantage. The much smaller degree of feedback with this design can also sometimes be an advantage; drivers of vehicles with rack and pinion steering can have their thumbs broken when a front wheel hits a bump, causing the steering wheel to kick to one side suddenly (leading to driving instructors telling students to keep their thumbs on the front of the steering wheel, rather than wrapping around the inside of the rim). This effect is even stronger with a heavy vehicle like a truck; recirculating ball steering prevents this degree of feedback, just as it prevents desirable feedback under normal circumstances.
The steering linkage connecting the steering box and the wheels usually conforms to a variation of Ackermann steering geometry, to account for the fact that in a turn, the inner wheel is actually traveling a path of smaller radius than the outer wheel, so that the degree of toe suitable for driving in a straight path is not suitable for turns.
As vehicles have become heavier and switched to front wheel drive, the effort to turn the steering wheel manually has increased - often to the point where major physical exertion is required. To alleviate this, auto makers have developed power steering systems. There are two types of power steering systems—hydraulic and electric/electronic. There is also a hydraulic-electric hybrid system possible.
A hydraulic power steering (HPS) uses hydraulic pressure supplied by an engine-driven pump to assist the motion of turning the steering wheel. Electric power steering (EPS) is more efficient than the hydraulic power steering, since the electric power steering motor only needs to provide assist when the steering wheel is turned, whereas the hydraulic pump must run constantly. In EPS the assist level is easily tunable to the vehicle type, road speed, and even driver preference. An added benefit is the elimination of environmental hazard posed by leakage and disposal of hydraulic power steering fluid.
An outgrowth of power steering is speed adjustable steering, where the steering is heavily assisted at low speed and lightly assisted at high speed. The auto makers perceive that motorists might need to make large steering inputs while manoeuvering for parking, but not while traveling at high speed. The first vehicle with this feature was the Citro?n SM with its Diravi layout, although rather than altering the amount of assistance as in modern power steering systems, it altered the pressure on a centring cam which made the steering wheel try to "spring" back to the straight-ahead position. Modern speed-adjustable power steering systems reduce the pressure fed to the ram as the speed increases, giving a more direct feel. This feature is gradually becoming commonplace across all new vehicles.
Four-wheel steering (or all wheel steering) is a system employed by some vehicles to increase vehicle stability while maneuvering at high speed, or to decrease turning radius at low speed.
In most four-wheel steering systems, the rear wheels are steered by a computer and actuators. The rear wheels generally cannot turn as far as the Alternatively, several systems, including Delphi's Quadrasteer and the system in Honda's Prelude line, allow for the rear wheels to be steered in the opposite direction as the front wheels during low speeds. This allows the vehicle to turn in a significantly smaller radius — sometimes critical for large trucks or vehicles with trailers.
An exception is the case of rail transport by which rail tracks combined together with railroad switches provide the steering function.Many modern cars use steering mechanisms, where the steering wheel turns the pinion gear; the pinion moves the rack, which is a sort of linear gear which meshes with the pinion, from side to side.mechanism, which is still found on trucks and utility vehicles.This is a variation on the older and thus steers the wheels.The recirculating ball version of this apparatus reduces the considerable friction by placing large ball bearings between the teeth of the worm and those of the screw; at either end of the apparatus the balls exit from between the two pieces into a channel internal to the box which connects them with the other end of the apparatus, thus they are "recirThe rack and pinion design has the advantages of a large degree of feedback and direct steering "feel"; it also does not normally have any , or slack.culated".A disadvantage is that it is not adjustable, so that when it does wear and develop lash, the only cure is replacement.The recirculating ball mechanism has the advantage of a much greater , however, this is no longer an important advantage, leading to the increasing use of rack and pinion on newer cars.to account for wear, but it cannot be entirely eliminated or the mechanism begins to wear very rapidly.This design is still in use in trucks and other large vehicles, where rapidity of steering and direct feel are less important than robustness, maintainability, and mechanical advantage.The much smaller degree of feedback with this design can also sometimes be an advantage; drivers of vehicles with rack and pinion steering can have their thumbs broken when a front wheel hits a bump, causing the steering wheel to kick to one side suddenly (leading to driving instructors telling students to keep their thumbs on the front of the steering wheel, rather than wrapping around the inside of the rim). This effect is even stronger with a heavy vehicle like a truck; recirculating ball steering prevents this degree of feedback, just as it prevents desirable feedback under normal circumstances.As vehicles have become heavier and switched to front wheel drive , the effort to turn the steering wheel manually has increased - often to the point where major physical exertion is required.There are two types of power steering systems—hydraulic and electric/electronic.here is also a hydraulic-electric hybrid system possible.A hydraulic power steering (HPS) uses hydraulic pressure supplied by an engine-driven pump to assist the motion of turning the stElectric power steering (EPS) is more efficient than the hydraulic power steering, since the electric power steering motor only needs to provide assist when the steering wheel is turned, whereas the hydraulic pump must run constantly.eering wheel.In EPS the assist level is easily tunable to the vehicle type, road speed, and even driver preference.An added benefit is the elimination of environmental hazard posed by leakage and disposal of hydraulic power steering fluid.n outgrowth of power steering is speed adjustable steering, where the steering is heavily assisted at low speed and lightly assisted at high speed.The auto makers perceive that motorists might need to make large steering inputs while manoeuvering for parking, but not while traveling at high speed.The first vehicle with this feature was the Citro?n SM with its Diravi layout, although rather than altering the amount of assistance as in modern power steering systems, it altered the pressure on a centring cam which made the steering wheel try to "spring" back to the straight-ahead position.Modern speed-adjustable power steering systems reduce the pressure fed to the ram as the speed increases, The rear wheels giving a more direct feel.This feature is gradually becoming commonplace across all new vehicles.In most four-wheel steering systems, the rear wheels are steered by a computer and actuators.generally cannot turn as far as the Alternatively, several systems, including Delphi's Quadrasteer and the system in Honda's Prelude line, allow for the rear wheels to be steered in the opposite direction as the front wheels during low speeds.This allows the vehicle to turn in a significantly smaller radius — sometimes critical for large trucks or vehicles with trailers.
Electronic power steering system
What it is
Electrically powered steering uses an electric motor to drive either the power steering hydraulic pump or the steering linkage directly. The power steering function is therefore independent of engine speed, resulting in significant energy savings.
How it works :
Conventional power steering systems use an engine accessory belt to drive the pump, providing pressurized fluid that operates a piston in the power steering gear or actuator to assist the driver.
In electro-hydraulic steering, one electrically powered steering concept uses a high efficiency