裝載機(jī)液壓系統(tǒng)設(shè)計(jì)
裝載機(jī)液壓系統(tǒng)設(shè)計(jì),裝載,液壓,系統(tǒng),設(shè)計(jì)
說 明
1.根據(jù)學(xué)?!懂厴I(yè)設(shè)計(jì)(論文)工作暫行規(guī)定》,學(xué)生必須撰寫《畢業(yè)設(shè)計(jì)(論文)開題報(bào)告》。開題報(bào)告作為畢業(yè)設(shè)計(jì)(論文)答辯委員會(huì)對(duì)學(xué)生答辯資格審查的依據(jù)材料之一。
2.開題報(bào)告應(yīng)在指導(dǎo)教師指導(dǎo)下,由學(xué)生在畢業(yè)設(shè)計(jì)(論文)工作前期內(nèi)完成,經(jīng)指導(dǎo)教師簽署意見及所在專業(yè)教研室論證審查后生效。開題報(bào)告不合格者需重做。
3.畢業(yè)設(shè)計(jì)開題報(bào)告各項(xiàng)內(nèi)容要實(shí)事求是,逐條認(rèn)真填寫。其中的文字表達(dá)要明確、嚴(yán)謹(jǐn),語(yǔ)言通順,外來語(yǔ)要同時(shí)用原文和中文表達(dá)。第一次出現(xiàn)縮寫詞,須注出全稱。
4.開題報(bào)告中除最后一頁(yè)外均由學(xué)生填寫,填寫各欄目時(shí)可根據(jù)內(nèi)容另加附頁(yè)。
5.閱讀的主要參考文獻(xiàn)應(yīng)在10篇以上(土建類專業(yè)文獻(xiàn)篇數(shù)可酌減),其中外文資料應(yīng)占一定比例。本學(xué)科的基礎(chǔ)和專業(yè)課教材一般不應(yīng)列為參考資料。
6.參考文獻(xiàn)的書寫應(yīng)遵循畢業(yè)設(shè)計(jì)(論文)撰寫規(guī)范要求。
7.開題報(bào)告應(yīng)與文獻(xiàn)綜述、一篇外文譯文和外文原文復(fù)印件同時(shí)提交,文獻(xiàn)綜述的撰寫格式按畢業(yè)設(shè)計(jì)(論文)撰寫規(guī)范的要求,字?jǐn)?shù)在2000字左右。
畢業(yè)設(shè)計(jì)(論文)開題報(bào)告
學(xué)生姓名
馬杰
專 業(yè)
車輛工程
班 級(jí)
B13142
指導(dǎo)教師姓名
何濤
職 稱
教授
工作單位
北華航天工業(yè)學(xué)院
課題來源
教師自擬題目
課題性質(zhì)
應(yīng)用研究
課題名稱
裝載機(jī)液壓系統(tǒng)設(shè)計(jì)
本設(shè)計(jì)的科學(xué)依據(jù)
(科學(xué)意義和應(yīng)用前景,國(guó)內(nèi)外研究概況,目前技術(shù)現(xiàn)狀、水平和發(fā)展趨勢(shì)等)
一、課題的目的與意義
裝載機(jī)械匯集了多種學(xué)科最先進(jìn)的技術(shù),具有高效率、高精度、高自動(dòng)化和高柔性的特點(diǎn),裝載不再是離散型的生產(chǎn),為了能夠提供整廠的交付能力,設(shè)備的連線變得更加重要,從技術(shù)的角度來看,這是為了能夠更好地提供具有機(jī)械連接性、硬件、軟件一致性的需求。對(duì)于大量的生產(chǎn),連線生產(chǎn)能夠提高其生產(chǎn)效率。此課題開設(shè)的意義在于要求我們掌握氣動(dòng)技術(shù)從原理、元件至回路系統(tǒng)的液壓傳動(dòng)技術(shù)所必需的基礎(chǔ)知識(shí)和分析問題的方法,為我們進(jìn)一步應(yīng)用液壓傳動(dòng)技術(shù),設(shè)計(jì)液壓傳動(dòng)系統(tǒng)打下堅(jiān)實(shí)基礎(chǔ)。?
二、課題發(fā)展現(xiàn)狀和前景展望
國(guó)產(chǎn)輪式裝載機(jī)正在從低水平、低質(zhì)量、低價(jià)位、滿足功能型向高水平、高質(zhì)量、中價(jià)位、經(jīng)濟(jì)實(shí)用型過渡。從仿制仿造向自主開發(fā)過渡,各主要廠家不斷進(jìn)行技術(shù)投入,采用不同的技術(shù)路線,在關(guān)鍵部件及系統(tǒng)上技術(shù)創(chuàng)新,擺脫目前產(chǎn)品設(shè)計(jì)雷同,無自己特色和優(yōu)勢(shì)的現(xiàn)狀,從低水平的無序競(jìng)爭(zhēng)的怪圈中脫穎而出,成為裝載機(jī)行業(yè)的領(lǐng)先者。
大型和小型輪式裝載機(jī),在近幾年的發(fā)展過程中,受到客觀條件及市場(chǎng)總需求量的限制。競(jìng)爭(zhēng)最為激烈的中型裝載機(jī)更新速度將越來越快。根據(jù)各生產(chǎn)廠家的實(shí)際情況,重新進(jìn)行總體設(shè)計(jì),優(yōu)化各項(xiàng)性能指標(biāo),強(qiáng)化結(jié)構(gòu)件的強(qiáng)度及剛度,使整機(jī)可靠性得到大步提高。細(xì)化系統(tǒng)結(jié)構(gòu)。如動(dòng)力系統(tǒng)的減振、散熱系統(tǒng)的結(jié)構(gòu)優(yōu)化、工作裝置的性能指標(biāo)優(yōu)化及各鉸點(diǎn)的防塵、工業(yè)造型設(shè)計(jì)等。利用電子技術(shù)及負(fù)荷傳感技術(shù)來實(shí)現(xiàn)變速箱的自動(dòng)換擋及液壓變量系統(tǒng)的應(yīng)用,提高效率、節(jié)約能源、降低裝載機(jī)作業(yè)成本。提高安全性、舒適性。降低噪聲和排放,強(qiáng)化環(huán)保指標(biāo)。隨著人們環(huán)保意識(shí)的增強(qiáng),降低裝載機(jī)噪聲和排放的工作已迫在眉捷,現(xiàn)在許多大城市已經(jīng)制定機(jī)動(dòng)車的噪聲和排放標(biāo)準(zhǔn),工程建設(shè)機(jī)械若不符合排放標(biāo)準(zhǔn),將要限制在該地區(qū)的銷售。廣泛利用新材料、新工藝、新技術(shù),特別是機(jī)、電、液一體化技術(shù),提高產(chǎn)品的壽命和可靠性。
設(shè)計(jì)內(nèi)容和預(yù)期成果
(具體設(shè)計(jì)內(nèi)容和重點(diǎn)解決的技術(shù)問題、預(yù)期成果和提供的形式)
1、設(shè)計(jì)內(nèi)容
1、擬定裝載機(jī)液壓系統(tǒng)總體設(shè)計(jì)方案;
2、根據(jù)總體設(shè)計(jì)方案設(shè)計(jì)計(jì)算有關(guān)技術(shù)參數(shù)并選型;
3、根據(jù)總體設(shè)計(jì)方案對(duì)裝載機(jī)液壓系統(tǒng)進(jìn)行布局設(shè)計(jì)。
2、預(yù)期成果
1、完成各流程的對(duì)比,解析其中的差距;
2、完成論文。
擬采取設(shè)計(jì)方法和技術(shù)支持
(設(shè)計(jì)方案、技術(shù)要求、實(shí)驗(yàn)方法和步驟、可能遇到的問題和解決辦法等)
(1) 明確課題要求,查找收集相關(guān)資料,撰寫畢業(yè)設(shè)計(jì)開題報(bào)告;?
(2)調(diào)查研究、分析課題要求,確定裝載機(jī)液壓系統(tǒng)總體設(shè)計(jì)方案;?
(3)根據(jù)總體設(shè)計(jì)方案設(shè)計(jì)計(jì)算有關(guān)技術(shù)參數(shù)并選型;?
(4)繪制裝載機(jī)液壓系統(tǒng)總體布局圖;
(5)繪制裝載機(jī)液壓系統(tǒng)原件安裝圖;
(6)撰寫畢業(yè)設(shè)計(jì)說明書。
實(shí)現(xiàn)本項(xiàng)目已具備的條件
(包括過去學(xué)習(xí)、研究工作基礎(chǔ),現(xiàn)有主要儀器設(shè)備、設(shè)計(jì)環(huán)境及協(xié)作條件等)
1、 可以從圖書館借閱相關(guān)的文獻(xiàn)資料;
2、 調(diào)查相關(guān)公司使用的裝載機(jī)液壓系統(tǒng);
3、 了解各項(xiàng)工藝的技術(shù)要求;
4、 要了解裝載機(jī)液壓系統(tǒng)的相關(guān)知識(shí)。
各環(huán)節(jié)擬定階段性工作進(jìn)度
(以周為單位)
?1-2周 明確設(shè)計(jì)任務(wù)和目標(biāo)。有關(guān)資料收集,完成外文翻譯,相關(guān)知識(shí)學(xué)習(xí),完成開題報(bào)告。
3-6周? 擬訂研究方案。
7-10周? 研究方案具體實(shí)施。
11-13周?撰寫計(jì)算說明書,完成圖紙繪制。
13-16周 撰寫設(shè)計(jì)論文,相關(guān)表格填寫,申請(qǐng)答辯。
開 題 報(bào) 告 審 定 紀(jì) 要
時(shí) 間
地點(diǎn)
主持人
參
會(huì)
教
師
姓 名
職 務(wù)(職 稱)
姓 名
職 務(wù)(職 稱)
論
證
情
況
摘
要
記錄人:
指
導(dǎo)
教
師
意
見
指導(dǎo)教師簽名: 年 月 日
教
研
室
意
見
教研室主任簽名: 年 月 日
第 4 頁(yè) 共4頁(yè)
說 明
1.根據(jù)學(xué)?!懂厴I(yè)設(shè)計(jì)(論文)工作暫行規(guī)定》,學(xué)生必須撰寫畢業(yè)設(shè)計(jì)(論文)文獻(xiàn)綜述。文獻(xiàn)綜述作為畢業(yè)設(shè)計(jì)(論文)答辯委員會(huì)對(duì)學(xué)生答辯資格審查的依據(jù)材料之一。
2.文獻(xiàn)綜述應(yīng)在指導(dǎo)教師指導(dǎo)下,由學(xué)生在畢業(yè)設(shè)計(jì)(論文)工作前期內(nèi)完成,由指導(dǎo)教師簽署意見并經(jīng)所在專業(yè)教研室審查。
3.文獻(xiàn)綜述各項(xiàng)內(nèi)容要實(shí)事求是,文字表達(dá)要明確、嚴(yán)謹(jǐn),語(yǔ)言通順,外來語(yǔ)要同時(shí)用原文和中文表達(dá)。第一次出現(xiàn)縮寫詞,須注出全稱。
4.學(xué)生撰寫文獻(xiàn)綜述,閱讀的主要參考文獻(xiàn)應(yīng)在10篇以上(土建類專業(yè)文獻(xiàn)篇數(shù)可酌減),其中外文資料應(yīng)占一定比例。本學(xué)科的基礎(chǔ)和專業(yè)課教材一般不應(yīng)列為參考資料。
5.文獻(xiàn)綜述的撰寫格式按畢業(yè)設(shè)計(jì)(論文)撰寫規(guī)范的要求,字?jǐn)?shù)在2000字左右。文獻(xiàn)綜述應(yīng)與開題報(bào)告同時(shí)提交。
基于裝載機(jī)液壓系統(tǒng)設(shè)計(jì)的文獻(xiàn)綜述
摘 要:
隨裝載機(jī)主要用來裝卸散狀物料,也能進(jìn)行輕度的鏟掘工作,并且具有良好的機(jī)動(dòng)性能,廣泛使用于工廠、礦山、建筑、水電上程、道路、碼頭、農(nóng)田乃至家庭,是工程機(jī)械中保有量較大的品種之一。
裝載總體方案設(shè)計(jì)是裝載機(jī)設(shè)計(jì)的一個(gè)重要環(huán)節(jié),它對(duì)裝載機(jī)的設(shè)計(jì)質(zhì)量、使用性能和裝載機(jī)在市場(chǎng)上的競(jìng)爭(zhēng)力有著決定性的影響。裝載機(jī)性能的優(yōu)劣和作業(yè)效率的發(fā)揮,不僅與相關(guān)總成及部件的工作性能有著密切關(guān)系,而且在很大程度上取決于各有關(guān)總成及部件間的協(xié)調(diào)和參數(shù)匹配,取決于裝載機(jī)的總體布置。
裝載機(jī)的工作裝置和轉(zhuǎn)向機(jī)構(gòu)都采取液壓傳動(dòng),本文通過對(duì)工作裝置及轉(zhuǎn)向機(jī)構(gòu)工作要求和載荷分析對(duì)液壓系統(tǒng)進(jìn)行設(shè)計(jì)。主要包括對(duì)執(zhí)行元件,控制元件輔助元件的選擇、設(shè)計(jì)。
本文的設(shè)計(jì),能夠使讀者對(duì)工程機(jī)械總體方案設(shè)計(jì)及液壓系統(tǒng)設(shè)計(jì)進(jìn)一步加深了解,同?時(shí)能從中理會(huì)一些設(shè)計(jì)理念,為以后更好從事設(shè)計(jì)工作提供了幫助。
關(guān)鍵字:裝載機(jī) 液壓裝置 液壓系統(tǒng)
Abstract:
Loader?is?primarily?utilized?to?load?and?unload?piles?of?balk?cargo?and?also?do?some?light?excavations.?It?has?good?mobility,?applied?widely?in?factory,?mine?construction,?water?and?electricity,?road,?dock,?farmland?even?house,?and?it?is?a?most?important?model?of?construction?machinery.
The?design?of?overall?project?of?wheel?loader?is?a?important?link?in?designing?of?wheel?loader?itself,?which?has?vital?impact?on?the?quality,?working?property?and?competition?in?market.?The?property?is?superior?or?inferior?and?its?affect?rate?is?brought?into?play,?which?have?relationship?with?the?property?of?relative?components?and?are?determined?not?only?by?the?matching?of?parameter,?the?coordination?between?switchboard?and?the?relative?components,?also?by?the?total?decoration?of?wheel?loader.
Working?device?and?the?steering?mechanism?of?the?loader?all?adopt?fluid?drive?system.?The?article?carries?though?the?design?of?the?fluid?drive?system?though?the?working?demand?on?working?device?and?the?load?analysis.?It?mainly?includes?the?selection?and?design?toward?the?executive?component,?the?control?component?and?the?assistant?component.
The?design?the?author?chosen?in?this?article?can?make?readers?know?much?about?the?total?designing?project?of?engineering?mechanism?and?the?systematic?design?of?liquid-press,?at?the?same?time?comprehend?some?designing?concept,?which?will?provide?helpness?to?further?work?later.
Keywords:loader hydraulic transmission hydraulic pressure system
文?獻(xiàn)?綜?述
1 引言
裝載機(jī)是一種廣泛用于公路、鐵路、建筑、水電、港口、礦山等建筑工程的土石方施工機(jī)械,它主要用于鏟裝土壤、砂石、石灰、煤炭等散狀物料,也可對(duì)礦石、硬土等作輕度鏟挖作業(yè)。換裝不同的輔助工作裝置還可進(jìn)行推土、起重和其他物料如木材的裝卸作業(yè)。在道路、特別是在高等級(jí)公路施工中,裝載機(jī)用于路基工程的填挖、瀝青混合料和水泥混凝土料場(chǎng)的集料與裝料等作業(yè)。此外還可進(jìn)行推運(yùn)土壤、刮平地面和牽引其他機(jī)械等作業(yè)。由于裝載機(jī)具有作業(yè)速度快、效率高、機(jī)動(dòng)性好、操作輕便等優(yōu)點(diǎn),因此它成為工程建設(shè)中土石方施工的主要機(jī)種之一。
液壓控制系統(tǒng)是裝載機(jī)械的核心部分。裝載機(jī)中主動(dòng)力的輸出、傳動(dòng)機(jī)構(gòu)的運(yùn)動(dòng)、裝載執(zhí)行機(jī)構(gòu)的動(dòng)作及相互配合,都是由控制系統(tǒng)指令操作的。其控制方法有機(jī)械、電、氣動(dòng)、電子、光電或射流等,都各具特色,一般根據(jù)裝載機(jī)械的自動(dòng)化水平的生產(chǎn)要求選擇。如:傳統(tǒng)的裝載機(jī)械控制系統(tǒng)采用凸輪分配軸機(jī)械式控制及采用繼電器、接觸器控制電路,其復(fù)雜程度隨著執(zhí)行機(jī)構(gòu)增多以及調(diào)整部位的增大而加大,使得機(jī)器也越來越復(fù)雜,給制造、調(diào)整、使用和維護(hù)均帶來不便;后來出現(xiàn)的電氣控制、液動(dòng)控制、光電控制,可用微機(jī)、傳感技術(shù)、新型傳動(dòng)技術(shù)取代笨重的機(jī)械控制柜和驅(qū)動(dòng)裝置,使零件數(shù)量劇減,結(jié)構(gòu)大為簡(jiǎn)化,體積也隨之減少,同時(shí)改善了生產(chǎn)過程中清潔衛(wèi)生。其中液動(dòng)控制系統(tǒng)在裝載機(jī)械中占有很大比例,近年來,隨著工業(yè)的飛速發(fā)展,液動(dòng)控制技術(shù)在工業(yè)自動(dòng)化領(lǐng)域得到了廣泛應(yīng)用。液動(dòng)控制是先將機(jī)械能轉(zhuǎn)變?yōu)橐簤耗埽賹⒁簤耗苻D(zhuǎn)變?yōu)闄C(jī)械能,降低了電力消耗和液壓油消耗,更易于控制,節(jié)省了大量勞動(dòng)力,實(shí)現(xiàn)了生產(chǎn)的自動(dòng)化管理。
2 液動(dòng)控制技術(shù)概述
以液體為工作介質(zhì)進(jìn)行能量傳遞的傳動(dòng)方式稱為液體傳動(dòng)。液動(dòng)技術(shù)是以液壓缸為動(dòng)力源,以液壓油為工作介質(zhì),進(jìn)行能量傳遞或信號(hào)傳遞的工程技術(shù),是實(shí)現(xiàn)各種生產(chǎn)控制、自動(dòng)控制的重要手段之一。
液動(dòng)控制技術(shù)的工作原理是利用液壓缸把電機(jī)或其他原動(dòng)機(jī)輸出的機(jī)械能轉(zhuǎn)換為液壓油的壓力能,然后在控制元件的作用下,通過執(zhí)行元件把壓力能轉(zhuǎn)換為直線運(yùn)動(dòng)或回轉(zhuǎn)運(yùn)動(dòng)形式的機(jī)械能,從而完成各種動(dòng)作,并對(duì)外做功。在氣動(dòng)控制系統(tǒng)中,氣動(dòng)發(fā)生裝置一般為液壓缸,它將原動(dòng)機(jī)供給的機(jī)械能轉(zhuǎn)換為氣體的壓力能;氣動(dòng)執(zhí)行元件則將壓力能轉(zhuǎn)化為機(jī)械能,完成規(guī)定動(dòng)作;在這兩部分之間,根據(jù)機(jī)械或設(shè)備工作循環(huán)運(yùn)動(dòng)的需求、按一定順序?qū)⒏鞣N控制元件(壓力控制閥、流量控制閥、方向控制閥和邏輯元件)、傳感元件和液動(dòng)輔助件連接起來。
液動(dòng)控制系統(tǒng)主要由五個(gè)部分組成:
(1)液壓動(dòng)力元件:把機(jī)械能轉(zhuǎn)換成液壓能的裝置,一般指液壓泵。?
(2)液壓執(zhí)行元件:執(zhí)行元件是指把液壓能轉(zhuǎn)換成機(jī)械能的裝置,一般是指做直線運(yùn)動(dòng)的液壓缸、做回轉(zhuǎn)運(yùn)動(dòng)的液壓馬達(dá)等。
(3)液壓控制元件:控制元件是指對(duì)液壓系統(tǒng)中液體的壓力、流量和流動(dòng)方向進(jìn)行控制和調(diào)節(jié)的裝置。例如溢流閥、節(jié)流閥、換向閥等,這些元件的不同組合,能構(gòu)成完成不同功能的液壓系統(tǒng)。
(4)輔助裝置:輔助裝置是指除以上三種以外的其他裝置,如過濾器、油霧器、消聲器等。
(5)工作介質(zhì):工作介質(zhì)是指在氣壓系統(tǒng)中傳遞運(yùn)動(dòng)和動(dòng)力能量的液體,即液壓油。
3 液動(dòng)控制系統(tǒng)特點(diǎn):
(1)單位質(zhì)量的設(shè)備所能輸出的力、功率比較大,及同樣體積、質(zhì)量的裝置,液壓傳動(dòng)裝置可輸出更大的力和力矩。
(2)特別是與機(jī)械裝置相比,操作方便、省力,系統(tǒng)結(jié)構(gòu)空間的自由度大,布局安裝靈活,可構(gòu)成復(fù)雜系統(tǒng),且能在很大范圍內(nèi)實(shí)現(xiàn)無級(jí)調(diào)速,傳動(dòng)比可達(dá)(100~2000):1
(3)傳動(dòng)平穩(wěn),便于實(shí)現(xiàn)頻繁換向和自動(dòng)防止過載。
(4)與電氣控制相配合,可較方便的實(shí)現(xiàn)復(fù)雜的程序動(dòng)作和遠(yuǎn)程控制,以實(shí)現(xiàn)自動(dòng)化。
(5)液壓元件易實(shí)現(xiàn)系列化、標(biāo)準(zhǔn)化和通用化。
4 液動(dòng)控制技術(shù)的應(yīng)用
液動(dòng)技術(shù)是生產(chǎn)過程自動(dòng)化和機(jī)械化的有效手段之一,具有高速高效、清潔安全、低成本及易維護(hù)等優(yōu)點(diǎn),被廣泛應(yīng)用于輕工機(jī)械領(lǐng)域中,在機(jī)械裝載及生產(chǎn)過程中也正在發(fā)揮越來越重要的作用。其在各類裝載機(jī)械中均有大量應(yīng)用,可以縮短加工輔助時(shí)間,減輕工人勞動(dòng)強(qiáng)度,充分發(fā)揮設(shè)備的高效性能。如:
1.汽車制造業(yè):其中包括車身外殼被真空吸盤吸起和放下,在指定工位夾緊和定位,電焊機(jī)焊頭的快速接近、減速軟著陸后的變壓控制電焊等。
2.半導(dǎo)體電子及家電行業(yè):例如在半導(dǎo)體芯片、印刷電路等各種電子產(chǎn)品的裝配流水線上許多真空吸盤將一般齊抓很難抓起的顯像管、紙箱等物品輕輕地吸住,運(yùn)送到指定目標(biāo)位置。
3.加工制造業(yè):其中包括機(jī)械加工生產(chǎn)線上工件的準(zhǔn)確裝夾及搬送,對(duì)加速度限制十分嚴(yán)格的芯片搬運(yùn)系統(tǒng),采用了平穩(wěn)加速的SIN汽缸等。
4.介質(zhì)管道運(yùn)輸送業(yè):可以說,用管道輸送介質(zhì)的自動(dòng)化流程絕大多數(shù)采用氣動(dòng)控制。例如石油加工、氣體通過系統(tǒng)加壓輸送到每個(gè)用戶終端、化工的加工和生產(chǎn)等。
5.包裝業(yè):其中包括各種半自動(dòng)或全自動(dòng)包裝生產(chǎn)線,例如:粉狀、塊狀物料的自動(dòng)計(jì)量包裝,用于煙草工業(yè)的自動(dòng)卷煙和制動(dòng)包裝等許多工序。
6.機(jī)器人:例如裝配機(jī)器人在汽車零部件中的裝配,焊接機(jī)器人在高頻率的點(diǎn)焊、力控的準(zhǔn)確性等。
7.其他:例如車輛的剎車裝置,車門開閉裝置,顆粒狀物質(zhì)的篩選,魚雷、導(dǎo)彈的自動(dòng)控住裝置等。各種氣動(dòng)工具等也是氣動(dòng)技術(shù)應(yīng)用領(lǐng)域的一個(gè)重要側(cè)面。
5 結(jié)論
現(xiàn)代裝載機(jī)械是匯集了多種學(xué)科的先進(jìn)技術(shù),液動(dòng)控制技術(shù)是裝載機(jī)械的一個(gè)重要組成部分。此次設(shè)計(jì)的裝載機(jī)液壓系統(tǒng)的設(shè)計(jì)需借鑒了其他裝載機(jī)械控制系統(tǒng)的工作理,并在其基礎(chǔ)上加以改善,減少裝載加工過程中的認(rèn)為或機(jī)器差錯(cuò),確保裝載機(jī)械的可靠運(yùn)行,實(shí)現(xiàn)安全生產(chǎn)和清潔生產(chǎn),實(shí)現(xiàn)裝載過程的連續(xù)化生產(chǎn)。
參考文獻(xiàn)
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液壓系統(tǒng)
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Hydraulic System
作 者
Владимир
譯 名
弗拉基米爾(斯)
國(guó) 籍
俄羅斯
原文出處
科學(xué)出版中心
液壓系統(tǒng)
液壓傳動(dòng)和氣壓傳動(dòng)稱為流體傳動(dòng),是根據(jù)17世紀(jì)帕斯卡提出的液體靜壓力傳動(dòng)原理而發(fā)展起來的一門新興技術(shù),1795年英國(guó)約瑟夫?布拉曼(Joseph Braman,1749-1814),在倫敦用水作為工作介質(zhì),以水壓機(jī)的形式將其應(yīng)用于工業(yè)上,誕生了世界上第一臺(tái)水壓機(jī)。1905年將工作介質(zhì)水改為油,又進(jìn)一步得到改善。
第一次世界大戰(zhàn)(1914-1918)后液壓傳動(dòng)廣泛應(yīng)用,特別是1920年以后,發(fā)展更為迅速。液壓元件大約在 19 世紀(jì)末 20 世紀(jì)初的20年間,才開始進(jìn)入正規(guī)的工業(yè)生產(chǎn)階段。1925 年維克斯(F.Vikers)發(fā)明了壓力平衡式葉片泵,為近代液壓元件工業(yè)或液壓傳動(dòng)的逐步建立奠定了基礎(chǔ)。20 世紀(jì)初康斯坦丁?尼斯克(G?Constantimsco)對(duì)能量波動(dòng)傳遞所進(jìn)行的理論及實(shí)際研究;1910年對(duì)液力傳動(dòng)(液力聯(lián)軸節(jié)、液力變矩器等)方面的貢獻(xiàn),使這兩方面領(lǐng)域得到了發(fā)展。
第二次世界大戰(zhàn)(1941-1945)期間,在美國(guó)機(jī)床中有30%應(yīng)用了液壓傳動(dòng)。應(yīng)該指出,日本液壓傳動(dòng)的發(fā)展較歐美等國(guó)家晚了近 20 多年。在 1955 年前后 , 日本迅速發(fā)展液壓傳動(dòng),1956 年成立了“液壓工業(yè)會(huì)”。近20~30 年間,日本液壓傳動(dòng)發(fā)展之快,居世界領(lǐng)先地位。
液壓傳動(dòng)有許多突出的優(yōu)點(diǎn),因此它的應(yīng)用非常廣泛,如一般工業(yè)用的塑料加工機(jī)械、壓力機(jī)械、機(jī)床等;行走機(jī)械中的工程機(jī)械、建筑機(jī)械、農(nóng)業(yè)機(jī)械、汽車等;鋼鐵工業(yè)用的冶金機(jī)械、提升裝置、軋輥調(diào)整裝置等;土木水利工程用的防洪閘門及堤壩裝置、河床升降裝置、橋梁操縱機(jī)構(gòu)等;發(fā)電廠渦輪機(jī)調(diào)速裝置、核發(fā)電廠等等;船舶用的甲板起重機(jī)械(絞車)、船頭門、艙壁閥、船尾推進(jìn)器等;特殊技術(shù)用的巨型天線控制裝置、測(cè)量浮標(biāo)、升降旋轉(zhuǎn)舞臺(tái)等;軍事工業(yè)用的火炮操縱裝置、船舶減搖裝置、飛行器仿真、飛機(jī)起落架的收放裝置和方向舵控制裝置等。
一個(gè)完整的液壓系統(tǒng)由五個(gè)部分組成,即動(dòng)力元件、執(zhí)行元件、控制元件、輔助元件和液壓油。
動(dòng)力元件的作用是將原動(dòng)機(jī)的機(jī)械能轉(zhuǎn)換成液體的壓力能,指液壓系統(tǒng)中的油泵,它向整個(gè)液壓系統(tǒng)提供動(dòng)力。液壓泵的結(jié)構(gòu)形式一般有齒輪泵、葉片泵和柱塞泵。
執(zhí)行元件(如液壓缸和液壓馬達(dá))的作用是將液體的壓力能轉(zhuǎn)換為機(jī)械能,驅(qū)動(dòng)負(fù)載作直線往復(fù)運(yùn)動(dòng)或回轉(zhuǎn)運(yùn)動(dòng)。
控制元件(即各種液壓閥)在液壓系統(tǒng)中控制和調(diào)節(jié)液體的壓力、流量和方向。根據(jù)控制功能的不同,液壓閥可分為壓力控制閥、流量控制閥和方向控制閥。壓力控制閥又分為益流閥(安全閥)、減壓閥、順序閥、壓力繼電器等;流量控制閥包括節(jié)流閥、調(diào)整閥、分流集流閥等;方向控制閥包括單向閥、液控單向閥、梭閥、換向閥等。根據(jù)控制方式不同,液壓閥可分為開關(guān)式控制閥、定值控制閥和比例控制閥。
輔助元件包括油箱、濾油器、油管及管接頭、密封圈、壓力表、油位油溫計(jì)等。
液壓油是液壓系統(tǒng)中傳遞能量的工作介質(zhì),有各種礦物油、乳化液和合成型液壓油等幾大類。
液壓系統(tǒng)的作用就是幫助人類做工。主要是由執(zhí)行元件把壓力變成轉(zhuǎn)動(dòng)或往復(fù)運(yùn)動(dòng)。
液壓的原理:它是由兩個(gè)大小不同的液缸組成的,在液缸里充滿水或油。充水的叫“水壓機(jī)”;充油的稱“油壓機(jī)”。兩個(gè)液缸里各有一個(gè)可以滑動(dòng)的活塞,如果在小活塞上加一定值的壓力,根據(jù)帕斯卡定律,小活塞將這一壓力通過液體的壓強(qiáng)傳遞給大活塞,將大活塞頂上去。設(shè)小活塞的橫截面積是S1,加在小活塞上的向下的壓力是F1。于是,小活塞對(duì)液體的壓強(qiáng)為P=F1/SI, 能夠大小不變地被液體向各個(gè)方向傳遞”。大活塞所受到的壓強(qiáng)必然也等于P。若大活塞的橫截面積是S2,壓強(qiáng)P在大活塞上所產(chǎn)生的向上的壓力F2=PxS2截面積是小活塞橫截面積的倍數(shù)。從上式知,在小活塞上加一較小的力,則在大活塞上會(huì)得到很大的力,為此用液壓機(jī)來壓制膠合板、榨油、提取重物、鍛壓鋼材等。
液壓系統(tǒng)由信號(hào)控制和液壓動(dòng)力兩部分組成,信號(hào)控制部分用于驅(qū)動(dòng)液壓動(dòng)力部分中的控制閥動(dòng)作。
液壓動(dòng)力部分采用回路圖方式表示,以表明不同功能元件之間的相互關(guān)系。液壓源含有液壓泵、電動(dòng)機(jī)和液壓輔助元件;液壓控制部分含有各種控制閥,其用于控制工作油液的流量、壓力和方向;執(zhí)行部分含有液壓缸或液壓馬達(dá),其可按實(shí)際要求來選擇。
與機(jī)械傳動(dòng)、電氣傳動(dòng)相比,液壓傳動(dòng)具有以下優(yōu)點(diǎn):
1 液壓傳動(dòng)的各種元件,可以根據(jù)需要方便、靈活地來布置。
2 重量輕、體積小、運(yùn)動(dòng)慣性小、反應(yīng)速度快。
3 操縱控制方便,可實(shí)現(xiàn)大范圍的無級(jí)調(diào)速(調(diào)速范圍達(dá)2000:1)。
4 可自動(dòng)實(shí)現(xiàn)過載保護(hù)。
5 一般采用礦物油作為工作介質(zhì),相對(duì)運(yùn)動(dòng)面可自行潤(rùn)滑,使用壽命長(zhǎng)。
6 很容易實(shí)現(xiàn)直線運(yùn)動(dòng)。
7 很容易實(shí)現(xiàn)機(jī)器的自動(dòng)化,當(dāng)采用電液聯(lián)合控制后,不僅可實(shí)現(xiàn)更高程度的自動(dòng)控制過程,而且可以實(shí)現(xiàn)遙控。
液壓系統(tǒng)的缺點(diǎn):
1、由于流體流動(dòng)的阻力和泄露較大,所以效率較低。如果處理不當(dāng),泄露不僅污染場(chǎng)地,而且還可能引起火災(zāi)和爆炸事故。
2、由于工作性能易受到溫度變化的影響,因此不宜在很高或很低的溫度條件下工作。
3、液壓元件的制造精度要求較高,因而價(jià)格較貴。
4、由于液體介質(zhì)的泄露及可壓縮性影響,不能得到嚴(yán)格的傳動(dòng)比。
5、液壓傳動(dòng)出故障時(shí)不易找出原因;使用和維修要求有較高的技術(shù)水平。
在液壓系統(tǒng)及其系統(tǒng)中,密封裝置用來防止工作介質(zhì)的泄漏及外界灰塵和異物的侵入。其中起密封作用的元件,即密封件。外漏會(huì)造成工作介質(zhì)的浪費(fèi),污染機(jī)器和環(huán)境,甚至引起機(jī)械操作失靈及設(shè)備人身事故。內(nèi)漏會(huì)引起液壓系統(tǒng)容積效率急劇下降,達(dá)不到所需要的工作壓力,甚至不能進(jìn)行工作。侵入系統(tǒng)中的微小灰塵顆粒,會(huì)引起或加劇液壓元件摩擦副的磨損,進(jìn)一步導(dǎo)致泄漏。
因此,密封件和密封裝置是液壓設(shè)備的一個(gè)重要組成部分。它的工作的可靠性和使用壽命,是衡量液壓系統(tǒng)好壞的一個(gè)重要指標(biāo)。除間隙密封外,都是利用密封件,使相鄰兩個(gè)偶合表面間的間隙控制在需要密封的液體能通過的最小間隙以下。在接觸式密封中,分為自封式壓緊型密封和自封式自緊型密封(即唇形密封)兩種。
液壓系統(tǒng)的三大頑疾
1、發(fā)熱 由于傳力介質(zhì)(液壓油)在流動(dòng)過程中存在各部位流速的不同,導(dǎo)致液體內(nèi)部存在一定的內(nèi)摩擦,同時(shí)液體和管路內(nèi)壁之間也存在摩擦,這些都是導(dǎo)致液壓油溫度升高的原因。溫度升高將導(dǎo)致內(nèi)外泄漏增大,降低其機(jī)械效率。同時(shí)由于較高的溫度,液壓油會(huì)發(fā)生膨脹,導(dǎo)致壓縮性增大,使控制動(dòng)作無法很好的傳遞。解決辦法:發(fā)熱是液壓系統(tǒng)的固有特征,無法根除只能盡量減輕。使用質(zhì)量好的液壓油、液壓管路的布置中應(yīng)盡量避免彎頭的出現(xiàn)、使用高質(zhì)量的管路以及管接頭、液壓閥等。
2、振動(dòng) 液壓系統(tǒng)的振動(dòng)也是其痼疾之一。由于液壓油在管路中的高速流動(dòng)而產(chǎn)生的沖擊以及控制閥打開關(guān)閉過程中產(chǎn)生的沖擊都是系統(tǒng)發(fā)生振動(dòng)的原因。強(qiáng)的振動(dòng)會(huì)導(dǎo)致系統(tǒng)控制動(dòng)作發(fā)生錯(cuò)誤,也會(huì)使系統(tǒng)中一些較為精密的儀器發(fā)生錯(cuò)誤,導(dǎo)致系統(tǒng)故障。解決辦法:液壓管路應(yīng)盡量固定,避免出現(xiàn)急彎。避免頻繁改變液流方向,無法避免時(shí)應(yīng)做好減振措施。整個(gè)液壓系統(tǒng)應(yīng)有良好的減振措施,同時(shí)還要避免外來振源對(duì)系統(tǒng)的影響。
3、泄漏 液壓系統(tǒng)的泄漏分為內(nèi)泄漏和外泄漏。內(nèi)泄漏指泄漏過程發(fā)生在系統(tǒng)內(nèi)部,例如液壓缸活塞兩邊的泄漏、控制閥閥芯與閥體之間的泄漏等。內(nèi)泄漏雖然不會(huì)產(chǎn)生液壓油的損失,但是由于發(fā)生泄漏,既定的控制動(dòng)作可能會(huì)受到影響,直至引起系統(tǒng)故障。外泄漏是指發(fā)生在系統(tǒng)和外部環(huán)境之間的泄漏。液壓油直接泄漏到環(huán)境中,除了會(huì)影響系統(tǒng)的工作環(huán)境外,還會(huì)導(dǎo)致系統(tǒng)壓力不夠引發(fā)故障。泄漏到環(huán)境中的液壓油還有發(fā)生火災(zāi)的危險(xiǎn)。解決辦法:采用質(zhì)量較好的密封件,提高設(shè)備的加工精度。
液壓元件將向高性能、高質(zhì)量、高可靠性、系統(tǒng)成套方向發(fā)展;向低能耗、低噪聲、振動(dòng)、無泄漏以及污染控制、應(yīng)用水基介質(zhì)等適應(yīng)環(huán)保要求方向發(fā)展;開發(fā)高集成化高功率密度、智能化、機(jī)電一體化以及輕小型微型液壓元件;積極采用新工藝、新材料和電子、傳感等高新技術(shù)。
液力偶合器向高速大功率和集成化的液力傳動(dòng)裝置發(fā)展,開發(fā)水介質(zhì)調(diào)速型液力偶合器和向汽車應(yīng)用領(lǐng)域發(fā)展,開發(fā)液力減速器,提高產(chǎn)品可靠性和平均無故障工作時(shí)間;液力變矩器要開發(fā)大功率的產(chǎn)品,提高零部件的制造工藝技術(shù),提高可靠性,推廣計(jì)算機(jī)輔助技術(shù),開發(fā)液力變矩器與動(dòng)力換檔變速箱配套使用技術(shù);液粘調(diào)速離合器應(yīng)提高產(chǎn)品質(zhì)量,形成批量,向大功率和高轉(zhuǎn)速方向發(fā)展。
附錄 (外文翻譯——原文)
Hydraulic System
Hydraulic presser drive and air pressure drive hydraulic fluid as the transmission is made according to the 17th century, Pascal's principle of hydrostatic pressure to drive the development of an emerging technology, the United Kingdom in 1795 ? Braman Joseph (Joseph Braman ,1749-1814), in London water as a medium to form hydraulic press used in industry, the birth of the world's first hydraulic press. Media work in 1905 will be replaced by oil-water and further improved.
After the World War I (1914-1918) ,because of the extensive application of hydraulic transmission, especially after 1920, more rapid development. Hydraulic components in the late 19th century about the early 20th century, 20 years, only started to enter the formal phase of industrial production. 1925 Vickers (F. Vikers) the invention of the pressure balanced vane pump, hydraulic components for the modern industrial or hydraulic transmission of the gradual establishment of the foundation. The early 20th century G ? Constantimscofluct- uations of the energy carried out by passing theoretical and practical research; in 1910 on the hydraulic trans- mission (hydraulic coupling, hydraulic torque converter, etc.) contributions, so that these two areas of development.
The Second World War (1941-1945) period, in the United States 30% of machine tool applications in the hydraulic transmission. It should be noted that the development of hydraulic transmission in Japan than Europe and the United States and other countries for nearly 20 years later. Before and after in 1955, the rapid development of Japan's hydraulic drive, set up in 1956, "Hydraulic Industry." Nearly 20 to 30 years, the development of Japan's fast hydraulic transmission, a world leader.
Hydraulic transmission There are many outstanding advantages, it is widely used, such as general industrial use of plastics processing machinery, the pressure of machinery, machine tools, etc.; operating machinery engineering machinery, construction machinery, agricultural machinery, automobiles, etc.; iron and steel indu-stry metallurgical machinery, lifting equipment, such as roller adjustment device; civil water projects with flood control and dam gate devices, bed lifts installations, bridges and other manipulation of institutions; speed turbine power plant installations, nuclear power plants, etc.; ship from the deck heavy machinery (winch), the bow doors, bulkhead valve, stern thruster, etc.; special antenna technology giant with control devices, measurement buoys, movements such as rotating stage; military industrial control devices used in artillery, ship antirolling devices, aircraft simulation, aircraft retractable landing gear and rudder control devices and other devices.
A complete hydraulic system consists of five parts, namely, power components, the implementation of components, control components, auxiliary components and hydraulic oil.
The role of dynamic components of the original motive fluid into mechanical energy to the pressure that the hydraulic system of pumps, it is to power the entire hydraulic system. The structure of the form of hydraulic pump gears are generally pump, vane pump and piston pump.
Implementation of components (such as hydraulic cylinders and hydraulic motors) which is the pressure of the liquid can be converted to mechanical energy to drive the load for a straight line reciprocating movement or rotational movement.
Control components (that is, the various hydraulic valves) in the hydraulic system to control and regulate the pressure of liquid, flow rate and direction. According to the different control functions, hydraulic pressure control valve can be divided into valves, flow control valves and directional control valve. Pressure control valves are divided into benefits flow valve (safety valve), pressure relief valve, sequence valve, pressure relays, etc.; flow control valves including throttle, adjusting the valves, flow diversion valve sets, etc.; directional control valve includes a one-way valve , one-way fluid control valve, shuttle valve, valve and so on. Under the control of different ways, can be divided into the hydraulic valve control switch valve, control valve and set the value of the ratio control valve.
Auxiliary components, including fuel tanks, oil filters, tubing and pipe joints, seals, pressure gauge, oil level, such as oil dollars.
Hydraulic oil in the hydraulic system is the work of the energy transfer medium, there are a variety of mineral oil, emulsion oil hydraulic molding Hop categories.
The role of the hydraulic system is to help humanity work. Mainly by the implementation of components to rotate or pressure into a reciprocating motion.
Hydraulic principle :it consists of two cylinders of different sizes and composition of fluid in the fluid full of water or oil. Water is called "hydraulic press"; the said oilfilled "hydraulic machine." Each of the two liquid a sliding piston, if the increase in the small piston on the pressure of a certain value, according to Pascal's law, small piston to the pressure of the pressure through the liquid passed to the large piston, piston top will go a long way to go. Based cross-sectional area of the small piston is S1, plus a small piston in the downward pressure on the F1. Thus, a small piston on the liquid pressure to P = F1/SI, Can be the same size in all directions to the transmission of liquid. "By the large piston is also equivalent to the inevitable pressure P. If the large piston is the cross-sectional area S2, the pressure P on the piston in the upward pressure generated F2 = PxS2 Cross-sectional area is a small multiple of the piston cross-sectional area. From the type known to add in a small piston of a smaller force, the piston will be in great force, for which the hydraulic machine used to suppress plywood, oil, extract heavy objects, such as forging steel.
? Hydraulic system and hydraulic power control signal is composed of two parts, the signal control of some parts of the hydraulic power used to drive the control valve movement.
Part of the hydraulic power means that the circuit diagram used to show the different functions of the interrelationship between components. Containing the source of hydraulic pump, hydraulic motor and auxiliary components; hydraulic control part contains a variety of control valves, used to control the flow of oil, pressure and direction; operative or hydraulic cylinder with hydraulic motors, according to the actual requirements of their choice.
With mechanical transmission, electrical transmission compared to the hydraulic drive has the following advantages:
1 A variety of hydraulic components, can easily and flexibly to layout.
2 Light weight, small size, small inertia, fast response.
3 To facilitate manipulation of control, enabling a wide range of stepless speed regulation (speed range of 2000:1).
4 To achieve overload protection automatically.
5 The general use of mineral oil as a working medium, the relative motion can be self-lubricating surface, long service life.
6 It is easy to achieve linear motion.
7 It is easy to achieve the automation of machines, when the joint control of the use of electro-hydraulic, not only can achieve a higher degree of process automation, and remote control can be achieved.
The shortcomings of the hydraulic system:
1 As a result of the resistance to fluid flow and leakage of the larger, so less efficient. If not handled properly, leakage is not only contaminated sites, but also may cause fire and explosion.
2 Vulnerable performance as a result of the impact of temperature change, it would be inappropriate in the high or low temperature conditions.
3 The manufacture of precision hydraulic components require a higher, more expensive and hence the price.
4 Due to the leakage of liquid medium and the compressibility and can not be strictly the transmission ratio.
5 Hydraulic transmission is not easy to find out the reasons for failure; the use and maintenance requirements for a higher level of technology.
In the hydraulic system and its system, the sealing device to prevent leakage of the work of media within and outside the dust and the intrusion of foreign bodies. Seals played the role of components, namely seals. Medium will result in leakage of waste, pollution and environmental machinery and even give rise to malfunctioning machinery and equipment for personal accident. Leakage within the hydraulic system will cause a sharp drop in volumetric efficiency, amounting to less than the required pressure, can not even work. Microinvasive system of dust particles, can cause or exacerbate friction hydraulic component wear, and further lead to leakage.
Therefore, seals and sealing device is an important hydraulic equipment components. The reliability of its work and life, is a measure of the hydraulic system an important indicator of good or bad. In addition to the closed space, are the use of seals, so that two adjacent coupling surface of the gap between the need to control the liquid can be sealed following the smallest gap. In the contact seal, pressed into self-seal-style and self-styled self-tight seal (ie, sealed lips) two.
The three hydraulic system diseases
1 As a result of heat transmission medium (hydraulic oil) in the flow velocity in various parts of the existence of different, resulting in the existence of a liquid within the internal friction of liquids and pipelines at the same time there is friction between the inner wall, which are a result of hydraulic the reasons for the oil temperature. Temperature will lead to increased internal and external leakage, reducing its mechanical efficiency. At the same time as a result of high temperature, hydraulic oil expansion will occur, resulting in increased compression, so that action can not be very good control of transmission. Solution: heat is the inherent characte -ristics of the hydraulic system, not only to minimize eradication. Use a good quality hydraulic oil, hydraulic piping arrangement should be avoided as far as possible the emergence of bend, the use of high-quality pipe and fittings, hydraulic valves, etc.
2 The vibration of the vibration of the hydraulic system is also one of its malaise. As a result of hydraulic oil in the pipeline flow of high-speed impact and the control valve to open the closure of the impact of the process are the reasons for the vibration system. Strong vibration control action will cause the system to error, the system will also be some of the more sophisticated equipment error, resulting in system failures. Solutions: hydraulic pipe should be fixed to avoid sharp bends. To avoid frequent changes in flow direction, can not avoid damping measures should be doing a good job. The entire hydraulic system should have a good damping measures, while avoiding the external local oscillator on the system.
3 The leakage of the hydraulic system leak into inside and outside the leakage leakage. Leakage refers to the process with the leak occurred in the system, such as hydraulic piston-cylinder on both sides of the leakage, the control valve spool and valve body, such as between the leakage. Although no internal leakage of hydraulic fluid loss, but due to leakage, the control of the established movements may be affected until the cause system failures. Outside means the occurrence of leakage in the system and the leakage between the external environment. Direct leakage of hydraulic oil into the environment, in addition to the system will affect the working environment, not enough pressure will cause the system to trigger a fault. Leakage into the environment of the hydraulic oil was also the danger of fire. Solution: the use of better quality seals to improve the machining accuracy of equipment.
Hydraulic components will be high-performance, high-quality, high reliability, the system sets the direction of development; to the low power, low noise, vibration, without leakage, as well as pollution control, water based media applications to adapt to environmental requirements, such as the direction of development; the development of highly integrated high power density, intelligence, mechatronics and micro-light mini-hydraulic components; active use of new techniques, new materials and electronics, sensing and other high-tech.
Hydraulic coupling to high-speed high-power and integrated development of hydraulic transmission equipment, development of water hydraulic coupling medium speed and the field of automotive applications to develop hydraulic reducer, improve product reliability and working hours MTBF; hydraulic torque converter to the development of high-power products, parts and components to improve the manufacturing process technology to improve reliability, promote computeraided technology, the development of hydraulic torque converter and power shift transmission technology supporting the use of ; Clutch fluid viscosity should increase the quality of products, the formation of bulk to the high-power and high-speed direction.
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注:1. 指導(dǎo)教師對(duì)譯文進(jìn)行評(píng)閱時(shí)應(yīng)注意以下幾個(gè)方面:①翻譯的外文文獻(xiàn)與畢業(yè)設(shè)計(jì)(論文)的主題是否高度相關(guān),并作為外文參考文獻(xiàn)列入畢業(yè)設(shè)計(jì)(論文)的參考文獻(xiàn);②翻譯的外文文獻(xiàn)字?jǐn)?shù)是否達(dá)到規(guī)定數(shù)量(3 000字以上);③譯文語(yǔ)言是否準(zhǔn)確、通順、具有參考價(jià)值。
2. 外文原文應(yīng)以附件的方式置于譯文之后。
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