【溫馨提示】====【1】設(shè)計(jì)包含CAD圖紙 和 DOC文檔，均可以在線預(yù)覽，所見即所得，，dwg后綴的文件為CAD圖，超高清，可編輯，無任何水印，，充值下載得到【資源目錄】里展示的所有文件======【2】若題目上備注三維，則表示文件里包含三維源文件，由于三維組成零件數(shù)量較多，為保證預(yù)覽的簡潔性，店家將三維文件夾進(jìn)行了打包。三維預(yù)覽圖，均為店主電腦打開軟件進(jìn)行截圖的，保證能夠打開，下載后解壓即可。======【3】特價促銷，，拼團(tuán)購買，，均有不同程度的打折優(yōu)惠，，詳情可咨詢QQ：1304139763 或者 414951605======【4】 題目最后的備注【QX系列】為店主整理分類的代號，與課題內(nèi)容無關(guān)，請忽視
本科畢業(yè)論文（設(shè)計(jì)）—中期檢查報告
本科畢業(yè)論文（設(shè)計(jì)）
中期檢查報告
論文題目
某乘用車轉(zhuǎn)向柱助力式轉(zhuǎn)向系統(tǒng)設(shè)計(jì)
班 級
姓 名
院（系）
導(dǎo) 師
報告時間
1．論文工作是否按開題報告預(yù)定的內(nèi)容及進(jìn)度安排進(jìn)行
1.1 預(yù)定內(nèi)容及進(jìn)度
第1 - 3 周：查閱相關(guān)資料，撰寫開題報告
第4 - 8 周：確定總體方案，進(jìn)行轉(zhuǎn)向系統(tǒng)設(shè)計(jì)計(jì)算；
第9 - 11 周：對轉(zhuǎn)向梯形進(jìn)行優(yōu)化設(shè)計(jì)；
第12-15 周：三維實(shí)體建模，繪制二維工程圖；
第16-18 周：撰寫畢業(yè)設(shè)計(jì)論文，復(fù)查設(shè)計(jì)內(nèi)容，準(zhǔn)備答辯。
1.2 實(shí)際內(nèi)容及進(jìn)度
第1 - 3 周：查閱相關(guān)資料，撰寫開題報告；
第4 - 8 周：確定總體方案，進(jìn)行轉(zhuǎn)向系統(tǒng)設(shè)計(jì)計(jì)算；
第9 - 12 周：三維實(shí)體建模；
1.3 實(shí)際設(shè)計(jì)與報告預(yù)定的差異
1.3.1在內(nèi)容繼續(xù)按照開題報告上擬定內(nèi)容進(jìn)行；
1.3.2 進(jìn)度安排上，先進(jìn)行了轉(zhuǎn)向系統(tǒng)的三維模型的建立，后期再對轉(zhuǎn)向梯形進(jìn)行優(yōu)化設(shè)計(jì)，對轉(zhuǎn)向節(jié)進(jìn)行有限元分析，最后對轉(zhuǎn)向系統(tǒng)的三維模型進(jìn)行修改和完善；
2．目前已完成的研究工作及結(jié)果
（1）了解了乘用車轉(zhuǎn)向系統(tǒng)的傳動形式，位置差異，以及在不同位置以各種方式進(jìn)行助力的轉(zhuǎn)向系統(tǒng)；
（2）初步建立了轉(zhuǎn)向系統(tǒng)的三維模型；
3．后期擬完成的研究工作及進(jìn)度安排
（1）擬完成的研究工作：
3.1.1對轉(zhuǎn)向梯形進(jìn)行優(yōu)化設(shè)計(jì)；
3.1.2對轉(zhuǎn)向節(jié)進(jìn)行有限元分析；
3.1.3對轉(zhuǎn)向系統(tǒng)的三維模型進(jìn)行修改和完善；
3.1.4繪制二維工程圖；
3.1.5撰寫畢業(yè)論文；
（2）進(jìn)度安排：
第12 - 14 周：對轉(zhuǎn)向梯形進(jìn)行優(yōu)化設(shè)計(jì)，對轉(zhuǎn)向節(jié)進(jìn)行有限元分析；
第14 - 15 周：三維模型的修改和完善；
第16 - 18 周：撰寫畢業(yè)設(shè)計(jì)論文，復(fù)查設(shè)計(jì)內(nèi)容，準(zhǔn)備答辯。
4．存在的困難與問題
（1）部分設(shè)計(jì)數(shù)據(jù)的選定范圍，加工制造過程中各個部件的合理性和可行性存在問題；
（2）通過觀察實(shí)體模型以及查閱資料，選取合理參數(shù)
5．如期完成全部論文工作的可能性
按照中期擬定工作安排，可如期完成論文工作；
中期報告檢查組意見：
組長（簽字）：
年 月 日
- 5 -
畢畢業(yè)設(shè)計(jì)中期報告業(yè)設(shè)計(jì)中期報告課題：某乘用車轉(zhuǎn)向柱助力式轉(zhuǎn)向系統(tǒng)設(shè)計(jì)學(xué)號：工作進(jìn)度對照u預(yù)定第4-8 周：確定總體方案，進(jìn)行轉(zhuǎn)向系統(tǒng)設(shè)計(jì)計(jì)算；第9-12 周：轉(zhuǎn)向梯形進(jìn)行優(yōu)化；轉(zhuǎn)向節(jié)有限元分析；第13-15 周：三維實(shí)體建模，繪制二維工程圖；u實(shí)際第4-8 周：確定總體方案，進(jìn)行轉(zhuǎn)向系統(tǒng)設(shè)計(jì)計(jì)算；第9-12 周：初步建立轉(zhuǎn)向系統(tǒng)的三維模型過程中存在的困難過程中存在的困難部分設(shè)計(jì)數(shù)據(jù)的取值，各個部件加工與其裝配的合理性和可行性問題；解決辦法解決辦法通過觀察實(shí)體模型以及查閱資料，選取合理參數(shù)；后期進(jìn)度安排第12-14 周：對轉(zhuǎn)向梯形進(jìn)行優(yōu)化設(shè)計(jì)，對轉(zhuǎn)向節(jié)進(jìn)行有限元分析；第14-15 周：對三維模型進(jìn)行修改和完善；繪制二維圖； 畢業(yè)論文（設(shè)計(jì)）—開題報告
本科畢業(yè)論文（設(shè)計(jì)）
開 題 報 告
論文題目
某乘用車轉(zhuǎn)向柱助力式轉(zhuǎn)向系統(tǒng)設(shè)計(jì)
班 級
姓 名
院（系）
導(dǎo) 師
開題時間
- 0 -
1．課題研究的目的和意義
隨著近些年來社會生活的汽車化, 汽車的保有量不斷增加, 由此造成交通錯綜復(fù)雜, 使得轉(zhuǎn)向盤的操作頻率增大, 這就需要減輕駕駛疲勞,提高操縱的輕便性和靈活性, 對動力轉(zhuǎn)向系統(tǒng)的要求也越來越高, 現(xiàn)今廣泛使用的液壓式動力向系統(tǒng)存在著制造工藝復(fù)雜, 對密封要求嚴(yán)格、維修保養(yǎng)困難等缺陷, 已不能滿足日益發(fā)展的要求, 同時隨著電子技術(shù)在發(fā)動機(jī)、變速器、制動器和懸架等系統(tǒng)的廣泛應(yīng)用, 電動助力轉(zhuǎn)向(Electric Power Steering, 簡稱 EPS) 技術(shù)應(yīng)運(yùn)而生, 成為世界汽車技術(shù)發(fā)展的研究熱點(diǎn)。國內(nèi)研究EPS的主要是幾所高校(如清華大學(xué)、合肥工業(yè)大學(xué)、北京理工大學(xué)、華南理工大學(xué)、武漢理工大學(xué)等),且大都局限于理論和計(jì)算機(jī)仿真。[1-3]。電動助力轉(zhuǎn)向系統(tǒng)較傳統(tǒng)的液壓動力轉(zhuǎn)向優(yōu)越很多: 結(jié)構(gòu)簡單，車輛布置設(shè)計(jì)容易，節(jié)約燃料, 能夠提高主動安全性, 并且有利于環(huán)保, 是一項(xiàng)緊扣現(xiàn)代汽車發(fā)展主題的高新技術(shù), 因此它有逐步取代傳統(tǒng)液壓動力轉(zhuǎn)向的趨勢。[2]
電動轉(zhuǎn)向助力按助力位置不同可分為轉(zhuǎn)向柱助力式、小齒輪助力式、雙小齒輪助力式以及齒條助力式。
此次設(shè)計(jì)的目的是設(shè)計(jì)一套轉(zhuǎn)向柱助力式轉(zhuǎn)向系統(tǒng)，確定總體結(jié)構(gòu)方案，而后在方案基礎(chǔ)上轉(zhuǎn)向系統(tǒng)的設(shè)計(jì)計(jì)算以及轉(zhuǎn)向梯形[4]的優(yōu)化設(shè)計(jì)，從實(shí)際駕駛的舒適性及安全性能角度出發(fā)，進(jìn)行優(yōu)化設(shè)計(jì)[5]和可行性分析，建立三維實(shí)體模型。
2．國內(nèi)外研究現(xiàn)狀
目前，國外 EPS 的機(jī)械結(jié)構(gòu)部分都相對成熟完善，各派系各零部件企業(yè)都有自己的獨(dú)特之處。主要發(fā)展方向集中在控制策略、性能匹配以及可靠性等方面。早期 EPS簡單的助力曲線早已不能適應(yīng)當(dāng)代汽車的要求，目前 EPS 不僅僅是提供轉(zhuǎn)向助力，而是與整車操穩(wěn)性能相匹配，綜合各種影響因素，從而在某些工況下通過對轉(zhuǎn)向系統(tǒng)施加阻尼或是補(bǔ)償?shù)?，以獲得更好的駕駛感覺。EPS 產(chǎn)品基本上都能實(shí)現(xiàn)轉(zhuǎn)向助力功能, 但也存在一定問題, 如轉(zhuǎn)向盤抖振、噪聲大、左右轉(zhuǎn)向不對稱等。在產(chǎn)業(yè)化方面, 整車企業(yè)在電控技術(shù)及 EPS 的行業(yè)標(biāo)準(zhǔn)方面存在滯后性, EPS 研發(fā)單位與整車企業(yè)的全面合作尚不夠深入, 因此其樣機(jī)得不到全面的考核,涉及整車操縱穩(wěn)定性能方面的研究較少。為了適應(yīng)市場潮流，國內(nèi)諸多企業(yè)也開始 EPS 的研發(fā)。但都是處于起步階段，大多處在設(shè)計(jì)和性能驗(yàn)證階段，只有少數(shù)企業(yè)將管柱助力式 EPS 應(yīng)用在量產(chǎn)車型上。[6]
EPS 系統(tǒng)通常由傳感器 (車速傳感器、轉(zhuǎn)矩傳感器、轉(zhuǎn)向角傳感器)、電子控制器 ECU、執(zhí)行器 (電動機(jī)、電磁離合器和減速機(jī)構(gòu)) 等 3 部分組成。[7]
2.1 扭矩傳感器
在現(xiàn)有技術(shù)基礎(chǔ)上,扭矩傳感器將向低價格和多功能兩個方向發(fā)展[8]。
2.1.1 低價格傳感器
該種傳感器是在目前批量生產(chǎn)的扭矩傳感器的基礎(chǔ)上,進(jìn)行技術(shù)革新, 通過采用新的材料, 減少組成傳感器的零件數(shù)量, 從而降低傳感器的生產(chǎn)成本而形成的。但是它只能測出扭矩信號,而不能測量轉(zhuǎn)角。
2.1.2 多功能傳感器
隨著車輛底盤控制系統(tǒng)的發(fā)展, 除需要知道轉(zhuǎn)向盤力矩信號外,還迫切需要轉(zhuǎn)向盤轉(zhuǎn)角信號, 供EPS、AFS (Active Front Wheel Steering) 和 ESP(Electronic StabilityProgram)等控制器使用。為滿足功能要求, 并提高傳感器的安裝方便性, 降低成本,需要在扭矩傳感器的基礎(chǔ)上, 集成轉(zhuǎn)角傳感器。
2.2 電機(jī)
電動助力轉(zhuǎn)向系統(tǒng)得到了廣泛應(yīng)用, 它不但被安裝在微型車上, 還應(yīng)用于經(jīng)濟(jì)性轎車, 并逐漸向中級轎車和高級轎車上發(fā)展。隨著車輛質(zhì)量和體積的增加, 對電機(jī)的輸出扭矩提出了更高的要求。最初電機(jī)的輸出電流是 25 A, 現(xiàn)在已經(jīng)發(fā)展到了 90 A, 以后還有繼續(xù)增大的趨勢。
2.3 ECU
電動助力轉(zhuǎn)向系統(tǒng)的 ECU 一般安裝在駕駛艙中。但是在某些情況下, ECU 必須安裝在發(fā)動機(jī)罩下面，在這種情況下, 就應(yīng)該提高 ECU 的防水性能和耐高溫性能。同時, 還要增加一個溫度傳感器, 直接測量 ECU 的環(huán)境溫度, 并根據(jù)環(huán)境溫度的高低,采取相應(yīng)的措施, 保護(hù) ECU。
3. 本課題的研究內(nèi)容及技術(shù)方案
本論文主要包括轉(zhuǎn)向柱助力式轉(zhuǎn)向系統(tǒng)的總體設(shè)計(jì)、轉(zhuǎn)向梯形的優(yōu)化設(shè)計(jì)和轉(zhuǎn)向系統(tǒng)完整的三維實(shí)體模型，并繪制工程圖。
3.1轉(zhuǎn)向系統(tǒng)的總體設(shè)計(jì)
3.1.1扭矩傳感器
扭矩傳感器的功能是測量駕駛員作用在轉(zhuǎn)向盤上的力矩的大小，是EPS的主輸入信號之一。考慮主副電壓輸出特性，耐久可靠性能。
3.1.2電動機(jī)
電動機(jī)輸出適宜的輔助力矩，要求電流轉(zhuǎn)速、電流扭矩特性曲線符合性能、耐久可靠性要求。
3.1.3減速機(jī)構(gòu)
減速機(jī)構(gòu)與電動機(jī)相連，起減速增扭的作用，對傳動效率，耐磨性能有一定的要求。
3.1.3裝配后整車轉(zhuǎn)向性能
必須符合國家車輛管理部門對整車的強(qiáng)制檢驗(yàn)項(xiàng)目要求、整車操縱穩(wěn)定性要求。
3.2轉(zhuǎn)向梯形的優(yōu)化設(shè)計(jì)
1）轉(zhuǎn)向梯形優(yōu)化設(shè)計(jì)的模型的建立。
2）轉(zhuǎn)向梯形的數(shù)學(xué)模型的建立。
3）利用MATLAB進(jìn)行分析[9]，得出優(yōu)化解。
4. 本設(shè)計(jì)的特色
1）建立在電動助力的基礎(chǔ)上，符合節(jié)能環(huán)保和科學(xué)技術(shù)發(fā)展的的要求。
2）通過對轉(zhuǎn)向柱助力式轉(zhuǎn)向系統(tǒng)的總體設(shè)計(jì)，轉(zhuǎn)向梯形的優(yōu)化設(shè)計(jì)，與汽車整體轉(zhuǎn)向系統(tǒng)的工作實(shí)況結(jié)合，對實(shí)際工程設(shè)計(jì)有很大幫助。
3）利用MATLAB軟件進(jìn)行分析優(yōu)化，得出設(shè)計(jì)的最優(yōu)結(jié)果。
5. 進(jìn)度安排
第1 - 3 周：查閱相關(guān)資料，撰寫開題報告；
第4 - 8 周：確定總體方案，進(jìn)行轉(zhuǎn)向系統(tǒng)設(shè)計(jì)計(jì)算；
第9 - 11 周：對轉(zhuǎn)向梯形進(jìn)行優(yōu)化設(shè)計(jì)；
第12-15 周：三維實(shí)體建模，繪制二維工程圖；
第16-18 周：撰寫畢業(yè)設(shè)計(jì)論文，復(fù)查設(shè)計(jì)內(nèi)容，準(zhǔn)備答辯。
6. 參考文獻(xiàn)
[1] 閆俊，張欣：汽車電動助力轉(zhuǎn)向技術(shù)分析 北京交通大學(xué) 機(jī)械與電子控制工程學(xué)院 北京
[2] 余卓平 孟 濤，陳 慧，張立軍：電動助力轉(zhuǎn)向系統(tǒng)的技術(shù)發(fā)展趨勢 同濟(jì)大學(xué)汽車學(xué)院 20050904
[3]黃榕清，向鐵明，許迎東：電動助力轉(zhuǎn)向的原理及發(fā)展 華南理工大學(xué) 汽車工程學(xué)院廣東 廣州
[4] 張習(xí)泉：轉(zhuǎn)向梯形應(yīng)用簡析 成都市工業(yè)職業(yè)技術(shù)學(xué)校汽車工程系 成都
[5] 李玉民1，李旭宏1，過學(xué)迅2：轉(zhuǎn)向梯形驅(qū)動機(jī)構(gòu)的運(yùn)動分析及優(yōu)化設(shè)計(jì) 1.東南大學(xué)交通學(xué)院 南京 2武漢理工大學(xué)
[6] 楊洪斌：汽車轉(zhuǎn)向管柱的有限元分析及設(shè)計(jì)優(yōu)化 四川綿陽三力股份有限公司 綿陽
[7] 羅新聞：汽車可變轉(zhuǎn)向系統(tǒng)結(jié)構(gòu)及工作原理 201112
[8] 易愛斌：轉(zhuǎn)向柱式電動助力轉(zhuǎn)向（C-EPS）系統(tǒng)的技術(shù)分析與技術(shù)確認(rèn)研究華中科技大學(xué) 機(jī)械工程 20060828
[9] 楊俊治1，楊文興2，周強(qiáng)1 2：基于MATLAB的轉(zhuǎn)向梯形機(jī)構(gòu)的優(yōu)化研究
1.蘭州電源車輛研究所有限公司 2.蘭州理工大學(xué) 機(jī)電工程學(xué)院
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The motor turning system
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 changed, the hydraulic pressure boost from the traditional machinery changes (Hydraulic Power Steering, is called HPS), the electrically controlled hydraulic pressure boost changes (Elect ric Hydraulic Power Steering, is called EHPS), develops the electrically operated boost steering system (Elect ric 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 和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.
汽車轉(zhuǎn)向系統(tǒng)
隨著汽車電子技術(shù)的迅猛發(fā)展，人們對汽車轉(zhuǎn)向操縱性能的要求也日益提高。汽車轉(zhuǎn)向系統(tǒng)已從傳統(tǒng)機(jī)械轉(zhuǎn)向、液壓助力轉(zhuǎn)向(Hydraulic Power Steering ，簡稱HPS) 、電控液壓助力轉(zhuǎn)向( Elect ric Hydraulic PowerSteering ， 簡稱EHPS) ， 發(fā)展到電動助力轉(zhuǎn)向系統(tǒng)(Elect ric Power Steering ，簡稱EPS) ，最終還將過渡到線控轉(zhuǎn)向系統(tǒng)(Steer By Wire ，簡稱SBW)。
機(jī)械轉(zhuǎn)向系統(tǒng)是指以駕駛員的體力作為轉(zhuǎn)向能源，其中所有傳力件都是機(jī)械的，汽車的轉(zhuǎn)向運(yùn)動是由駕駛員操縱方向盤，通過轉(zhuǎn)向器和一系列的桿件傳遞到轉(zhuǎn)向車輪而實(shí)現(xiàn)的。機(jī)械轉(zhuǎn)向系由轉(zhuǎn)向操縱機(jī)構(gòu)、轉(zhuǎn)向器和轉(zhuǎn)向傳動機(jī)械3大部分組成。
通常根據(jù)機(jī)械式轉(zhuǎn)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(yīng)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(zhuǎn)向力時) 。在循環(huán)球式轉(zhuǎn)向器中，輸入轉(zhuǎn)向圈與輸出的轉(zhuǎn)向搖臂擺角是成正比的;在齒輪齒條式轉(zhuǎn)向器中，輸入轉(zhuǎn)向圈數(shù)與輸出的齒條位移是成正比的。循環(huán)球式轉(zhuǎn)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(qiáng)，故廣泛應(yīng)用于載貨汽車上。齒輪齒條式轉(zhuǎn)向器與循環(huán)球式相比，最大特點(diǎn)是剛性大，結(jié)構(gòu)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(zhuǎn)向盤，所以具有對路面狀態(tài)反應(yīng)靈敏的優(yōu)點(diǎn)，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(yīng)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(jī)械轉(zhuǎn)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(jī)械式轉(zhuǎn)向系統(tǒng)已經(jīng)無法滿足需要，動力轉(zhuǎn)向系統(tǒng)應(yīng)運(yùn)而生，它能在駕駛員轉(zhuǎn)動方向盤的同時提供助力，動力轉(zhuǎn)向系統(tǒng)分為液壓轉(zhuǎn)向系統(tǒng)和電動轉(zhuǎn)向系統(tǒng)2 種。其中液壓轉(zhuǎn)向系統(tǒng)是目前使用最為廣泛的轉(zhuǎn)向系統(tǒng)。
液壓轉(zhuǎn)向系統(tǒng)在機(jī)械系統(tǒng)的基礎(chǔ)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(jī)的動力驅(qū)動液壓泵、空氣壓縮機(jī)和發(fā)電機(jī)等，以液力、氣力或電力增大駕駛員操縱前輪轉(zhuǎn)向的力量，使駕駛員可以輕便靈活地操縱汽車轉(zhuǎn)向，減輕了勞動強(qiáng)度，提高了行駛安全性。
液壓助力轉(zhuǎn)向系統(tǒng)從發(fā)明到現(xiàn)在已經(jīng)有了大約半個世紀(jì)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(shù)成熟至今仍被廣泛應(yīng)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(zhuǎn)向機(jī)構(gòu)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(dá)到轉(zhuǎn)向助力的作用。傳統(tǒng)液壓式動力轉(zhuǎn)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(zhuǎn)閥式和滑閥式。
隨著液壓動力轉(zhuǎn)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(zhuǎn)向系統(tǒng)卻存在許多的缺點(diǎn): ①由于其本身的結(jié)構(gòu)決定了其無法保證車輛在任何工況下轉(zhuǎn)動轉(zhuǎn)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(zhuǎn)向輕便性和高速時的操縱穩(wěn)定性; ②汽車的轉(zhuǎn)向特性受駕駛員駕駛技術(shù)的影響嚴(yán)重; ③轉(zhuǎn)向傳動比固定，使汽車轉(zhuǎn)向響應(yīng)特性隨車速、側(cè)向加速度等變化而變化，駕駛員必須提前針對汽車轉(zhuǎn)向特性幅值和相位的變化進(jìn)行一定的操作補(bǔ)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(fù)擔(dān)，也使汽車轉(zhuǎn)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(zhuǎn)向系統(tǒng)的基礎(chǔ)上增加速度傳感器，使汽車能夠隨著車速的變化自動調(diào)節(jié)操縱力的大小，在一定程度上緩和了傳統(tǒng)的液壓轉(zhuǎn)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(zhuǎn)向系統(tǒng)，它是比較成熟和應(yīng)用廣泛的轉(zhuǎn)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(zhuǎn)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(shù)的發(fā)展，汽車燃油節(jié)能的要求以及全球性倡導(dǎo)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(zhuǎn)向系統(tǒng)向著電動助力轉(zhuǎn)向系統(tǒng)發(fā)展。
電動助力轉(zhuǎn)向系統(tǒng)是現(xiàn)在汽車轉(zhuǎn)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(zhuǎn)向盤轉(zhuǎn)矩傳感器和車速傳感器的信號進(jìn)行分析處理后，控制電機(jī)產(chǎn)生適當(dāng)?shù)闹D(zhuǎn)矩，協(xié)助駕駛員完成轉(zhuǎn)向操作。近幾年來，隨著電子技術(shù)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(biāo)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(yīng)用，并且每年以300 萬臺的速度發(fā)展。
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.轉(zhuǎn)向是一個專業(yè)術(shù)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(yù)期的方向行駛. An exception is the case of rail transport by which rail tracks combined together with railroad switches provide the steering function.一個例外的情況是鐵路運(yùn)輸由路軌組合在一起鐵路道岔提供轉(zhuǎn)向功能。
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.許多現(xiàn)代轎車使用齒輪齒條式轉(zhuǎn)向器，在方向盤末端有轉(zhuǎn)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(yùn)動把轉(zhuǎn)矩通過轉(zhuǎn)向橫拉桿和一種叫做轉(zhuǎn)向節(jié)臂的短形臂傳遞給轉(zhuǎn)向輪的主銷。
mechanism, which is still found on trucks and utility vehicles.以前的設(shè)計(jì)往往采用循環(huán)球式轉(zhuǎn)向器，而這種轉(zhuǎn)向器仍然應(yīng)用在卡車和多用途車輛。This is a variation on the older and thus steers the wheels.這是一種老式的螺母和齒扇設(shè)計(jì)，該轉(zhuǎn)向管柱轉(zhuǎn)動大螺絲("蝸輪")，它與一個齒扇齒輪嚙合，當(dāng)蝸輪轉(zhuǎn)動時，齒扇也隨之轉(zhuǎn)動，一個安裝在齒扇軸上且與轉(zhuǎn)向聯(lián)動有關(guān)的搖臂帶動轉(zhuǎn)向節(jié)臂 ，從而使車輪轉(zhuǎn)動. 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".循環(huán)球式轉(zhuǎn)向器通過安裝滾珠減少螺母和螺桿之間的摩擦;兩根導(dǎo)管和螺母內(nèi)的螺旋管狀通道組合成兩條各自獨(dú)立的封閉的鋼球“流到”。
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 , or slack.齒輪齒條式轉(zhuǎn)向器設(shè)計(jì)具有很大程度的反饋和直接轉(zhuǎn)向"路感";它也通常不會有任何反彈，或呆滯。A disadvantage is that it is not adjustable, so that when it does wear and develop lash, the only cure is replacement.缺點(diǎn)是，它是不可調(diào)的，因此當(dāng)它磨損唯一的解決辦法更換。
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.循環(huán)球式轉(zhuǎn)向器的優(yōu)點(diǎn)是機(jī)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(zhuǎn)向系統(tǒng)，不過，這已不再是一個重要的優(yōu)勢，導(dǎo)致越來越多地在新型汽車應(yīng)用齒輪齒條式轉(zhuǎn)向器。 to account for wear, but it cannot be entirely eliminated or the mechanism begins to wear very rapidly.循環(huán)球式轉(zhuǎn)向器設(shè)計(jì)在中心也有明顯的沖擊，或"死點(diǎn)"。凡一分鐘交替方向盤出不來并不移動轉(zhuǎn)向機(jī)構(gòu);這是很容易可調(diào)螺桿的端部來減少磨損，但它并不能完全消除或機(jī)制開始磨損很快。 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.這項(xiàng)設(shè)計(jì)目前仍在使用中，在卡車和其他大型車輛，也應(yīng)用于迅速轉(zhuǎn)向，路感與穩(wěn)健性，可維護(hù)性，和機(jī)械的優(yōu)勢相比不太重要的場合。 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).較小程度的反饋，這樣的設(shè)計(jì)也有時是一種優(yōu)點(diǎn);當(dāng)前輪碰撞時，使用齒輪齒條轉(zhuǎn)向的司機(jī)只有自己的大拇指受傷，造成方向盤揭開一邊突然(因?yàn)轳{駛教練告訴學(xué)生把自己的大拇指在前面的方向盤，而非放在左右的內(nèi)邊緣). This effect is even stronger with a heavy vehicle like a