1附錄A液壓系統(tǒng)設(shè)計(jì)液壓技術(shù)被引入工業(yè)領(lǐng)域已經(jīng)有一百多年的歷史了，隨著工業(yè)的迅猛發(fā)展，液壓技術(shù)更日新月異。伴隨著數(shù)學(xué)、控制理論、計(jì)算機(jī)、電子器件和液壓流體學(xué)的發(fā)展，出現(xiàn)了液壓伺服系統(tǒng)，并作為一門應(yīng)用科學(xué)已經(jīng)發(fā)展成熟，形成自己的體系和一套行之有效的分析和設(shè)計(jì)方法。好了，不多說了，現(xiàn)在我和大家來說說液壓系統(tǒng)設(shè)計(jì)的方法和注意問題。舉個(gè)液壓系統(tǒng)在機(jī)床運(yùn)用的例子來和大家聊，并歡迎大家提出意見。1 設(shè)計(jì)機(jī)床液壓傳動(dòng)系統(tǒng)的依據(jù)1. 機(jī)床的總體布局和工藝要求，包括采用液壓傳動(dòng)所完成的機(jī)床運(yùn)動(dòng)種類、機(jī)械設(shè)計(jì)時(shí)提出可能用的液壓執(zhí)行元件的種類和型號、執(zhí)行元件的位置及其空間的尺寸范圍、要求的自動(dòng)化程度等。2. 機(jī)床的工作循環(huán)、執(zhí)行機(jī)構(gòu)的運(yùn)動(dòng)方式（移動(dòng)、轉(zhuǎn)動(dòng)或擺動(dòng)），以及完成的工作范圍。3. 液壓執(zhí)行元件的運(yùn)動(dòng)速度、調(diào)速范圍、工作行程、載荷性質(zhì)和變化范圍。4. 機(jī)床各部件的動(dòng)作順序和互鎖要求，以及各部件的工作環(huán)境與占地面積等。5. 液壓系統(tǒng)的工作性能，如工作平穩(wěn)性、可靠性、換向精度、停留時(shí)間和沖出量等方面的要求。6. 其它要求，如污染、腐蝕性、易燃性以及液壓裝置的質(zhì)量、外形尺寸和經(jīng)濟(jì)性等。2 設(shè)計(jì)液壓傳動(dòng)系統(tǒng)的步驟1. 明確對液壓傳動(dòng)系統(tǒng)的工作要求，是設(shè)計(jì)液壓傳動(dòng)系統(tǒng)的依據(jù)，由使用部門以技術(shù)任務(wù)書的形式提出。2. 擬定液壓傳動(dòng)系統(tǒng)圖。(1) 根據(jù)工作部件的運(yùn)動(dòng)形式，合理地選擇液壓執(zhí)行元件；(2) 根據(jù)工作部件的性能要求和動(dòng)作順序，列出可能實(shí)現(xiàn)的各種基本回路。此時(shí)應(yīng)注意選擇液壓挖掘機(jī)總體設(shè)計(jì)2合適的調(diào)速方案、速度換接方案，確定安全措施和卸荷措施，保證自動(dòng)工作循環(huán)的完成和順序動(dòng)作和可靠。液壓傳動(dòng)方案擬定后，應(yīng)按國家標(biāo)準(zhǔn)規(guī)定的圖形符號繪制正式原理圖。圖中應(yīng)標(biāo)注出各液壓元件的型號規(guī)格，還應(yīng)有執(zhí)行元件的動(dòng)作循環(huán)圖和電氣元件的動(dòng)作循環(huán)表。3. 計(jì)算液壓系統(tǒng)的主要參數(shù)和選擇液壓元件。(1) 計(jì)算液壓缸的主要參數(shù)；(2) 計(jì)算液壓缸所需的流量并選用液壓泵；(3) 選用油管；(4) 選取元件規(guī)格；(5) 計(jì)算系統(tǒng)實(shí)際工作壓力；(6) 計(jì)算功率，選用電動(dòng)機(jī)；(7) 發(fā)熱和油箱容積計(jì)算； 4. 進(jìn)行必要的液壓系統(tǒng)驗(yàn)算。5. 液壓裝置的結(jié)構(gòu)設(shè)計(jì)。6. 繪制液壓系統(tǒng)工作圖，編制技術(shù)文件。3 設(shè)計(jì)液壓傳動(dòng)系統(tǒng)時(shí)應(yīng)注意問題1. 在組合基本回路時(shí)，要注意防止回路間相互干擾，保證正常的工作循環(huán)。2. 提高系統(tǒng)的工作效率，防止系統(tǒng)過熱。例如功率小，可用節(jié)流調(diào)速系統(tǒng)；功率大，最好用容積調(diào)速系統(tǒng)；經(jīng)常停車制動(dòng)，應(yīng)使泵能夠及時(shí)地卸荷；在每一工作循環(huán)中耗油率差別很大的系統(tǒng)，應(yīng)考慮用蓄能器或壓力補(bǔ)償變量泵等效率高的回路。3. 防止液壓沖擊，對于高壓大流量的系統(tǒng)，應(yīng)考慮用液壓換向閥代替電磁換向閥，減慢換向速度；采用蓄能器或增設(shè)緩沖回路，消除液壓沖擊。4. 系統(tǒng)在滿足工作循環(huán)和生產(chǎn)率的前提下，應(yīng)力求簡單，系統(tǒng)越復(fù)雜，產(chǎn)生故障的機(jī)會(huì)就越多。系統(tǒng)要安全可靠，對于做垂直運(yùn)動(dòng)提升重物的執(zhí)行元件應(yīng)設(shè)有平衡回路；對有嚴(yán)格順序動(dòng)作要求的執(zhí)行元件應(yīng)采用行程控制的順序動(dòng)作回路。此外，還應(yīng)具有互鎖裝置和一些安全措施。5. 盡量做到標(biāo)準(zhǔn)化、系列化設(shè)計(jì)，減少專用件設(shè)計(jì)。4 使用液壓系統(tǒng)要注意的問題1. 使用者應(yīng)明白液壓系統(tǒng)的工作原理，熟悉各種操作和調(diào)整手柄的位置及旋向等。2. 開車前應(yīng)檢查系統(tǒng)上各調(diào)整手柄、手輪是否被無關(guān)人員動(dòng)過，電氣開關(guān)和行程開關(guān)的位3置是否正常，主機(jī)上工具的安裝是否正確和牢固等，再對導(dǎo)軌和活塞桿的外露部分進(jìn)行擦拭，而后才可開車。3. 開車時(shí)，首先啟動(dòng)控制油路的液壓泵，無專用的控制油路液壓泵時(shí)，可直接啟動(dòng)主液壓泵。4. 液壓油要定期檢查更換，對于新投入使用的液壓設(shè)備，使用3 個(gè)月左右即應(yīng)清洗油箱，更換新油。以后每隔半年至1 年進(jìn)行清洗和換油一次。5. 工作中應(yīng)隨時(shí)注意油液，正常工作時(shí)，油箱中油液溫度應(yīng)不超過60℃。油溫過高應(yīng)設(shè)法冷卻，并使用粘度較高的液壓油。溫度過低時(shí)，應(yīng)進(jìn)行預(yù)熱，或在運(yùn)轉(zhuǎn)前進(jìn)行間歇運(yùn)轉(zhuǎn)，使油溫逐步升高后，再進(jìn)入正式工作運(yùn)轉(zhuǎn)狀態(tài)。6. 檢查油面，保證系統(tǒng)有足夠的油量。7. 有排氣裝置的系統(tǒng)應(yīng)進(jìn)行排氣，無排氣裝置的系統(tǒng)應(yīng)往復(fù)運(yùn)轉(zhuǎn)多次，使之自然排出氣體。8. 油箱應(yīng)加蓋密封，油箱上面的通氣孔處應(yīng)設(shè)置空氣過濾器，防止污物和水分的侵入。加油時(shí)應(yīng)進(jìn)行過濾，使油液清潔。9. 系統(tǒng)中應(yīng)根據(jù)需要配置粗、精過濾器，對過濾器應(yīng)經(jīng)常地檢查、清洗和更換。10. 對壓力控制元件的調(diào)整，一般首先調(diào)整系統(tǒng)壓力控制閥----溢流閥，從壓力為零時(shí)開調(diào)，逐步提高壓力，使之達(dá)到規(guī)定壓力值；然后依次調(diào)整各回路的壓力控制閥。主油路液壓泵的安全溢流閥的調(diào)整壓力一般要大于執(zhí)行元件所需工作壓力的10%—25%?？焖龠\(yùn)動(dòng)液壓泵的壓力閥，其調(diào)整壓力一般大于所需壓力10%—20%。11. 流量控制閥要從小流量調(diào)到大流量，并且應(yīng)逐步調(diào)整。同步運(yùn)動(dòng)執(zhí)行元件的流量控制閥應(yīng)同時(shí)調(diào)整，要保證運(yùn)動(dòng)的平穩(wěn)性5 工作部件產(chǎn)生爬行的原因及排除方法1. 因?yàn)榭諝獾膲嚎s性較大，當(dāng)含有氣泡的液體到達(dá)高壓區(qū)而受到劇烈壓縮時(shí)，會(huì)使油液體液壓挖掘機(jī)總體設(shè)計(jì)4積變小，使工作部件產(chǎn)生爬行。采取措施：在系統(tǒng)回路的高處部 位設(shè)置排氣裝置，將空氣排除。2. 由于相對運(yùn)動(dòng)部件間的磨擦阻力太大或磨擦阻力變化，致使工作部件在運(yùn)動(dòng)時(shí)產(chǎn)生爬行。采取措施：對液壓缸、活塞和活塞桿等零件的形位公差和表面粗糙度有一定的要求；并應(yīng)保證液壓系統(tǒng)和液壓油的清潔，以免臟物夾入相對運(yùn)動(dòng)件的表面間，從而增大磨擦阻力。3. 運(yùn)動(dòng)件表面間潤滑不良，形成干磨擦或半磨擦，也容易導(dǎo)致爬行。采取措施：經(jīng)常檢查有相對運(yùn)動(dòng)零件的表面間潤滑情況，使其保持良好。4. 若液壓缸的活塞和活塞桿的密封定心不良，也會(huì)出現(xiàn)爬行。采取措施：應(yīng)卸除載荷，使液壓缸單獨(dú)動(dòng)作，測定出磨擦阻力后，校正定心。5. 因液壓缸泄漏嚴(yán)重，導(dǎo)致爬行。采取措施：減少泄漏損失，或加大液壓泵容量。6. 在工作過程中由于負(fù)載變化，引起系統(tǒng)供油波動(dòng)，導(dǎo)致工作部件爬行。 采取措施：注意選用小流量下保持性能穩(wěn)定的調(diào)速閥，并且在液壓缸和調(diào)速閥間盡量不用軟管聯(lián)接，否則會(huì)因軟管變形大，容易引起爬行現(xiàn)象。6 液壓系統(tǒng)油溫升高的原因、后果及解決措施液壓系統(tǒng)在工作中有能量損失，包括壓力損失、容積損失和機(jī)械損失三方面，這些損失轉(zhuǎn)化為熱能，使液壓系統(tǒng)的油溫升高。一般液壓系統(tǒng)的油溫應(yīng)控制在（30-60）℃范圍內(nèi)，最高不超過（60-70）℃。油溫升高會(huì)引起一系列不良后果： 1. 使油液粘度下降，泄漏增加，降低了容積效率，甚至影響工作機(jī)構(gòu)的正常運(yùn)動(dòng)； 2. 使油液變質(zhì)，產(chǎn)生氧化物雜質(zhì)，堵塞液壓元件中的小孔或縫隙，使之 不能正常工作；3. 引起熱膨脹系數(shù)不同的相對運(yùn)動(dòng)零件之間的間隙變小，甚至卡死，無法運(yùn)動(dòng)；4. 引起機(jī)床或機(jī)械的熱變形，破壞原有的精度。保證液壓系統(tǒng)正常工作溫度的措施：1. 當(dāng)壓力控制閥的調(diào)定值偏高時(shí)，應(yīng)降低工作壓力，以減少能量損耗；52. 由于液壓泵及其連接處的泄漏造成容積損失而發(fā)熱時(shí)，應(yīng)緊固各連接處，加強(qiáng)密封；3. 當(dāng)油箱容積小、散熱條件差時(shí)，應(yīng)適當(dāng)加大油箱容積，必要時(shí)設(shè)置冷卻器；4. 由于油液粘度太高，使內(nèi)磨擦增大而發(fā)熱時(shí)，應(yīng)選用粘度低的液壓油；5. 當(dāng)油管過于細(xì)長并彎曲，使油液的沿程阻力損失增大、油溫升高時(shí)，應(yīng)加大管徑，縮短管路，使油液通暢；6. 由于周圍環(huán)境溫度過高使油溫升高時(shí)，要利用隔熱材料和反射板等，使系統(tǒng)和外界隔絕；7. 高壓油長時(shí)間不必要地從溢流閥回油箱，使油溫升高時(shí)，應(yīng)改進(jìn)回路設(shè)計(jì)，采用變量泵或卸荷措施7 空氣侵入到液壓系統(tǒng)的不良后果及解決措施空氣侵入到液壓系統(tǒng)的不良后果主要有：1. 使油液具有一定的壓縮性，致使系統(tǒng)產(chǎn)生噪聲、振動(dòng)和引起運(yùn)動(dòng)部件的爬行，破壞了工作的平穩(wěn)性；2. 易使油液氧化變質(zhì)，降低油液的使用壽命。解決措施：(1) 空氣由油箱進(jìn)入系統(tǒng)的機(jī)會(huì)較多，如油箱的油量不足；液壓泵吸油管侵入油中太短；吸油管和回油管在油箱中距離太近或沒有用隔板隔開；回油飛濺，攪成泡沫；液壓泵吸入空氣；回油管沒有插入油箱，使回油沖出油面和箱壁，在油面上會(huì)產(chǎn)生大量氣泡，使空氣與油一起吸入系統(tǒng)。因此，油箱的油面要經(jīng)常保持足夠的高度；吸油管和回油管應(yīng)保證在最低油面以下，兩者要用隔板隔開；(2) 由于密封不嚴(yán)或管接頭處和液壓元件接合面處的螺釘擰得不緊，外界空氣就會(huì)從這些地方侵入；系統(tǒng)中低于大氣壓部分，如液壓泵的吸油腔、吸油管和壓油管中油流速度較高（壓力低）的局部區(qū)域；在系統(tǒng)停止工作，系統(tǒng)中回油腔的油液經(jīng)回油管返回油箱時(shí)，也會(huì)形成局部真空的區(qū)域，在這些區(qū)域空氣最容易侵入。因此，要盡量防止各處的壓力低于大氣壓力；各個(gè)密封部件均應(yīng)使用良好的密封裝置，管接頭和各接合面處的螺釘應(yīng)液壓挖掘機(jī)總體設(shè)計(jì)6擰緊；經(jīng)常清洗液壓泵吸油口處的過濾器，以防止吸油阻力增大而把溶解在油中的空氣游離出來進(jìn)入系統(tǒng)；(3) 對于主要的液壓設(shè)備，液壓缸上最好設(shè)有排氣裝置，以排除系統(tǒng)中的空氣。8 系統(tǒng)中流量不足的原因及解決措施1. 由于液壓泵流量不足，致使系統(tǒng)中流量不足時(shí)，應(yīng)檢查液壓泵零件是否有損壞情況，及時(shí)地更換或修復(fù)損壞超差件；如果因泵內(nèi)吸入空氣影響了液壓泵的流量，則要采取措施，防止空氣吸入，變量泵由于變量機(jī)構(gòu)工作不良影響泵的流量，應(yīng)對變量機(jī)構(gòu)拆卸、清洗或修理、更換；2. 壓力分配閥工作不良引起流量不足時(shí)，應(yīng)修理或更換；3. 因油液粘度不合適而影響流量時(shí)，要更換粘度適當(dāng)?shù)挠鸵?，并注意油溫對粘度的影響?4. 溢流閥工作不良影響流量時(shí)，應(yīng)采取措施，使其工作正常；5. 由于液壓缸、閥等元件泄漏嚴(yán)重，造成流量不足時(shí)，應(yīng)針對不同情況采取相應(yīng)的措施；6. 流量控制閥的調(diào)節(jié)機(jī)構(gòu)工作不正常時(shí)，應(yīng)根據(jù)零件損壞情況予以修復(fù)或更新、或拆開清洗，使調(diào)節(jié)機(jī)構(gòu)動(dòng)作靈活，工作正常。9 液壓系統(tǒng)中噪聲產(chǎn)生原因及解決措施1. 空氣侵入液壓系統(tǒng)是產(chǎn)生噪聲的主要原因。因?yàn)橐簤合到y(tǒng)侵入空氣時(shí)，在低壓區(qū)其體積較大，當(dāng)流到高壓區(qū)時(shí)受壓縮，體積突然縮小，而當(dāng)它流入低壓區(qū)時(shí)，體積突然增大，這種氣泡體積的突然改變，產(chǎn)生“爆炸”現(xiàn)象，因而產(chǎn)生噪聲，此現(xiàn)象通常稱為“空穴”。針對這個(gè)原因，常常在液壓缸上設(shè)置排氣裝置，以便排氣。另外在開車后，使執(zhí)行件以快速全行程往復(fù)幾次排氣，也是常用的方法；2. 液壓泵或液壓馬達(dá)質(zhì)量不好，通常是液壓傳動(dòng)中產(chǎn)生噪聲的主要部分。液壓泵的制造質(zhì)量不好，精度不符合技術(shù)要求，壓力與流量波動(dòng)大，困油現(xiàn)象未能很好消除，密封不好，以及軸承質(zhì)量差等都是造成噪聲的主要原因。在使用中，由于液壓泵零件磨損，間隙7過大，流量不足，壓力易波動(dòng)，同樣也會(huì)引起噪聲。面對上述原因，一是選擇質(zhì)量好的液壓泵或液壓馬達(dá)，二是加強(qiáng)維修和保養(yǎng)，例如若齒輪的齒形精度低，則應(yīng)對研齒輪，滿足接觸面要求；若葉片泵有困油現(xiàn)象，則應(yīng)修正配油盤的三角槽，消除困油；若液壓泵軸向間隙過大而輸油量不足，則應(yīng)修理，使軸向間隙在允許范圍內(nèi)；若液壓泵選用不對，則應(yīng)更換；3. 溢流閥不穩(wěn)定，如由于滑閥與閥孔配合不當(dāng)或錐閥與閥座接觸處被污物卡住、阻尼孔堵塞、彈簧歪斜或失效等使閥芯卡住或在閥孔內(nèi)移動(dòng)不靈，引起系統(tǒng)壓力波動(dòng)和噪聲。對此，應(yīng)注意清洗、疏通陰尼孔；對溢流閥進(jìn)行檢查，如發(fā)現(xiàn)有損壞，或因磨損超過規(guī)定，則應(yīng)及時(shí)修理或更換；4. 換向閥調(diào)整不當(dāng)，使換向閥閥芯移動(dòng)太快，造成換向沖擊，因而產(chǎn)生噪聲與振動(dòng)。在這種情況下，若換向閥是液壓換向閥，則應(yīng)調(diào)整控制油路中的節(jié)流元件，使換向平穩(wěn)無沖擊。在工作時(shí)，液壓閥的閥芯支持在彈簧上，當(dāng)其頻率與液壓泵輸油率的脈動(dòng)頻率或與其它振源頻率相近時(shí)，會(huì)引起振動(dòng)，產(chǎn)生噪聲。這時(shí)，通過改變管路系統(tǒng)的固有頻率，變動(dòng)控制閥的位置或適當(dāng)?shù)丶有钅芷鳎瑒t能防振降噪。5. 機(jī)械振動(dòng)，如油管細(xì)長，彎頭多而未加固定，在油流通過時(shí)，特別是當(dāng)流速較高時(shí)，容易引起管子抖動(dòng)；電動(dòng)機(jī)和液壓泵的旋轉(zhuǎn)部分不平衡，或在安裝時(shí)對中不好，或聯(lián)軸節(jié)松動(dòng)等，均能產(chǎn)生振動(dòng)和噪聲。對此應(yīng)采取的措施有：較長油管應(yīng)彼此分開，并與機(jī)床壁隔開，適當(dāng)加設(shè)支承管夾；調(diào)整電動(dòng)機(jī)和液壓泵的安裝精度；重新安裝聯(lián)軸節(jié)，保證同軸度小于0.1MM等。10 在液壓系統(tǒng)中安裝油管的注意事項(xiàng)：1. 吸油管不應(yīng)漏氣，各接頭要緊牢和密封好；2. 吸油管道上應(yīng)設(shè)置過濾器；3. 回油管應(yīng)插入油箱的油面以下，防止飛濺泡沫和混入空氣；4. 電磁換向閥內(nèi)的泄漏油液，必須單獨(dú)設(shè)回油管，以防止泄漏回油時(shí)產(chǎn)生背壓，避免阻礙閥芯運(yùn)動(dòng)；液壓挖掘機(jī)總體設(shè)計(jì)85. 溢流閥回油口不許與液壓泵的入口相接；6. 全部管路應(yīng)進(jìn)行兩次安裝，第一次試裝，第二次正式安裝。試裝后，拆下油管，用20%的硫酸或鹽酸溶液酸洗，再用10%的蘇打水中和，最后用溫水清洗，待干燥后涂油進(jìn)行二次安裝。注意安裝時(shí)不得有砂子和氧化皮等。11 在液壓系統(tǒng)中安裝液壓元件時(shí)的注意事項(xiàng)：1. 液壓元件安裝前，要用煤油清洗，自制的重要元件應(yīng)進(jìn)行密封和耐壓試驗(yàn)，試驗(yàn)壓力可取工作壓力的2倍，或取最高使用壓力的1.5倍。試驗(yàn)時(shí)要分級進(jìn)行，不要一下子升到試驗(yàn)壓力，每升一級檢查一次；2. 方向控制閥應(yīng)保證軸線呈水平位置安裝；3. 板式元件安裝時(shí)，要檢查進(jìn)出油口處的密封圈是否合乎要求，安裝前密封圈應(yīng)突出安裝平面，保證安裝后有一定的壓縮量，以防泄漏；4. 板式元件安裝時(shí)，固定螺釘?shù)臄Q緊力要均勻，使元件的安裝平面與元件底板平面能很好地接觸。12 在液壓系統(tǒng)中安裝液壓泵時(shí)的注意事項(xiàng)：1. 液壓泵傳動(dòng)軸與電動(dòng)機(jī)驅(qū)動(dòng)軸同軸度偏差小于0.1MM，一般采用撓性聯(lián)軸節(jié)聯(lián)結(jié)，不允許用V帶直接帶動(dòng)泵軸轉(zhuǎn)動(dòng)，以防泵軸受徑向力過大，影響泵的正常運(yùn)轉(zhuǎn)；2. 液壓泵的旋轉(zhuǎn)方向和進(jìn)、出油口應(yīng)按要求安裝；3. 各類液壓泵的吸油高度，一般要小于0.5M。13 如何清洗液壓系統(tǒng)液壓系統(tǒng)在制造、試驗(yàn)、使用和儲(chǔ)存中都會(huì)受到污染，而清洗是清除污染，使液壓油、液壓元件和管道等保持清潔的重要手段。生產(chǎn)中，液壓系統(tǒng)的清洗通常有主系統(tǒng)清洗和全系統(tǒng)清洗。全系統(tǒng)清洗是指對液壓裝置的整個(gè)回路進(jìn)行清洗，在清洗前應(yīng)將系統(tǒng)恢復(fù)到實(shí)際運(yùn)轉(zhuǎn)狀態(tài)。清洗介質(zhì)可用液壓油，清洗時(shí)間一般為2-94小時(shí)，特殊情況下也不超過10小時(shí)，清洗效果以回路濾網(wǎng)上無雜質(zhì)為標(biāo)準(zhǔn)。清洗時(shí)注意事項(xiàng)：1. 一般液壓系統(tǒng)清洗時(shí)，多采用工作用的液壓油或試車油。不能用煤油、汽油、酒精、蒸氣或其它液體，防止液壓元件、管路、油箱和密封件等受腐蝕； 2. 清洗過程中，液壓泵運(yùn)轉(zhuǎn)和清洗介質(zhì)加熱同時(shí)進(jìn)行。清洗油液的溫度為（50-80）℃時(shí)，系統(tǒng)內(nèi)的橡膠渣是容易除掉的；3. 清洗過程中，可用非金屬錘棒敲擊油管，可連續(xù)地敲擊，也可不連續(xù)地敲擊，以利清除管路內(nèi)的附著物；4. 液壓泵間歇運(yùn)轉(zhuǎn)有利于提高清洗效果，間歇時(shí)間一般為（10-30）min5. 在清洗油路的回路上，應(yīng)裝過濾器或?yàn)V網(wǎng)。剛開始清洗時(shí)，因雜質(zhì)較多，可采用80目濾網(wǎng)，清洗后期改用150目以上的濾網(wǎng)；6. 清洗時(shí)間一般為（48-60）小時(shí)，要根據(jù)系統(tǒng)的復(fù)雜程度、過濾精度要求和污染程度等因素決定； 7. 為了防止外界濕氣引起銹蝕，清洗結(jié)束時(shí)，液壓泵還要連續(xù)運(yùn)轉(zhuǎn)，直到溫度恢復(fù)正常為止；8. 清洗后要將回路內(nèi)的清洗油排除干凈。液壓挖掘機(jī)總體設(shè)計(jì)10附錄BHydraulic system designHydraulic technology has been the introduction of an industrial area have 100 years of history. With the rapid industrial development of hydraulic technology more with each passing day. Along with mathematics， control theory, computer， electronic components and hydraulic fluid sciences， a hydraulic servo system, and as an application of science has been developed， develop its own system， and a set of effective analysis and design methods. Well，not that， and now I say all of the hydraulic system design methods and attention to the issue. For the hydraulic system of the machine used examples to chat with everyone， and welcome comments. 1 Machine design of the hydraulic drive system based on 1. The overall layout of machine tools and technological requirements, including the use of hydraulic machine performed by type of campaign, mechanical design made possible with the implementation of the hydraulic components of the types and models, implementation of the components of the space and its location size, the requirements of the degree of automation. 2. Machine work cycle, the implementing agency of movement (Mobile, rotate or swing), and the completion of the work. 3. Hydraulic Components movement speed, speed of reference, itinerary, load changes in the nature and scope. 4. Machine movements of the various components of the order and interlocking requirements, and the various components of the working environment and covers such. 115. The hydraulic system performance, such as work smooth, reliability, precision to the other, time and stay out of the volume of the request. 6. Other requirements, such as pollution, corrosive, flammable, and the quality of hydraulic devices, Size and shape of the economy and so on. 2 Hydraulic system design steps1. A clear right hydraulic system requirements for the work, hydraulic system is designed on the basis that users in the technical tasks of the form. 2. The hydraulic drive system development plans. a. According to the working parts of exercise a reasonable choice of hydraulic components; b. Under the working parts of the performance requirements and movements of the order, listing possible to achieve the basic circuit. It should be noted at this time to choose a suitable speed, speed-exchange programs to determine safety and unloading, automatically guarantee the completion of the work cycle of action and order and reliable. Hydraulic drive programming, the national standard should be the official graphic symbol mapping diagram. Tagging should map out the components of the hydraulic model specifications, It should also be a component of the implementation of action plans and the recycling of electrical components in the table of operating cycle. 3. Calculation of the main hydraulic system parameters and the choice of hydraulic components. (1) Calculation of the hydraulic cylinder main parameters;(2) Calculation of the hydraulic cylinder flow and use hydraulic pumps; (3) Selection of tubing;(4) Selecting components specifications; (5) Calculation of the actual system pressure;(6) The calculation of power, motor selection;(7) Heating and fuel tank volume;4. Necessary hydraulic system checked. 5. Hydraulic design of the structure.6. Drawing hydraulic system map, the preparation of technical documents. 3 Hydraulic system design to be a problem1. The basic composition of the loop, We must pay attention to preventing mutual interference between the circuit, and ensure normal work cycle. 2. To improve the efficiency of systems to prevent overheating. For example, small power available throttle control system; Power, speed volume with the best system; Regular parking brake. should be able to pump in a timely manner unloading; In each work cycle oil consumption vary greatly system should consider using pressure accumulator or variable compensation such as high efficiency pump circuit.液壓挖掘機(jī)總體設(shè)計(jì)123. Prevent hydraulic shock, for large high-pressure flow system, should consider the use of hydraulic valve replaced electromagnetic valve, to slow down the pace of change; using accumulator or additional buffer circuit, the elimination of hydraulic shocks. 4. The system in meeting the productivity of the work cycle and, under the premise should be as simple as possible, the more complex the system, have the opportunity to fault the more. To a safe and reliable system for doing vertical movement of heavy loads upgrade components should be implemented there is a balancing loop; on the strict requirements of the order moves the implementation program components should be used to control movements in the order loop. Moreover, they should also have interlocking devices and some safety measures. 5. As well standardized, serialized design, reducing exclusive designs.4 Hydraulic systems use the issue to the attention 1. Users should understand that the hydraulic system of principle, familiar with the various operational and adjustment of the location and the handle to the other roundabout.2. Drive system should be checked prior to the adjustment on the handle, hand wheel was irrelevant whether the officers Touched, Electrical switches and switch itinerary and whether it is normal for the location, host of installation tools and firmly correct. another pair of rails and the exposed parts of the piston rod for clean, and then can drive.3. When driving a car, to start the control of the hydraulic pump asphalt, without special control asphalt hydraulic pump, can directly initiate hydraulic pump.4. Hydraulic oil to replace regular checks for the new use of hydraulic equipment, three months or so that the washing tanks, the replacement oil. After every six months to a year for an oil change and cleaning. 5. Should always keep in oil, normal working hours, the oil tank temperature should not exceed 60 ℃ .High temperature to be cooling, and the use of higher viscosity hydraulic oil. Low temperature should be carried out when preheating, or in operation before the intermittent operation, gradually rising temperature, enter the formal functioning of the state. 6. Check oil levels, and ensure the system has sufficient fuel. 7. Installation of the exhaust system should exhaust, no venting device system should be reciprocating operation times, so that the natural gas emitted. 8. Should be impressed with the seal tank, the fuel tank above the air vents should install air filters, prevent dirt and moisture intrusion. Filling should be filtered, clean oil. 9. The system should be based on need to configure coarse and fine filters, the filter should always check, cleaning and replacement.1310. Pressure control components of the adjustment, the general first adjustment system pressure relief valve-control valve. Pressure from zero returned, and gradually raising the pressure, so that they achieve the required pressure values; followed by the adjustment of the loop pressure control valve. The oil pump safety relief valve pressure adjustments will be greater than the general implementation of the necessary components of the work pressure10%—25 %. Rapid movement of the hydraulic pump pressure relief valve adjustment pressures generally greater than the pressure required for 10%—20%. 11.Flow control valve flow to small transferred large flow, and should be gradually adjusted. Synchronous execution of the component flow control valve should be adjusted. To ensure the movement stability.5 Crawling have working parts and the reasons for exclusion method 1. Because of the compressed air are greater. When the bubble of liquid containing high pressure zone and reach severe compression, the volume of oil will become smaller, working components produced crawling. Take measures to : loop in the system were installed height of the exhaust system to remove the air. 2. As the relative movement between the parts too much friction and friction resistance changes which has caused the campaign components generated crawling. Takes the measure : the hydraulic cylinder, piston and piston rod, and other parts of the form and position tolerances, and surface roughness have certain requirements; and should ensure that hydraulic systems and hydraulic oil clean dirt to avoid relative movement folder into the surface, thus increasing friction. 3. Surface movement among poor lubrication, to create friction or semi-friction, it is easy to crawl. Take the measures: regular checks of relative movement between parts of the lubrication of the surface, enabling it to maintain good.4. If the hydraulic cylinder piston and the piston rod sealing centering bad, there may be crawling. Take the measures: shed load, so that a separate action hydraulic cylinder was measured friction, centering correction.5. Due to serious hydraulic cylinder leak led to crawling.Take the measures: to reduce the leakage loss, or increased pump capacity. 6. In the course of their work load due to changes in oil supply system caused fluctuations, leading to crawl working parts. Take the measures: choose to remain small flow properties of the valve stability, and the hydraulic cylinder and valve between minimizing the hose connection, otherwise they will be flexible deformation, it can be easily aroused creeping phenomenon. 液壓挖掘機(jī)總體設(shè)計(jì)146 Hydraulic system temperature rise, consequences and solutions In the hydraulic system with energy work, including loss of pressure loss. volume losses and three mechanical losses, these losses into heat, so that the hydraulic system temperature increased. General hydraulic system temperature should be controlled (30-60) ℃, not exceeding the maximum (60-70) ℃. Temperature rise will cause a series of negative consequences : 1. The oil viscosity, leakage, reduce the volume efficiency and even affect the normal movement; 2. To enable the oil changed oxides produced impurities hydraulic components to plug the holes or cracks, so that they are not normal;3. Have different thermal expansion coefficients of the relative movement between the parts become smaller space, or even death card, not a campaign; 4. Machine tools or machinery caused the thermal deformation, damage to the original accuracy. Hydraulic system to ensure the normal operating temperature of measures : 1. When the pressure control valve to set the value at high pressure should be lowered to reduce energy loss;2. As the hydraulic pump and its connecting the volume caused by the leakage of heat loss, shall be securely fastened to the connecting and enhancing seal;3. When the fuel tank size small, poor conditions of heat, as appropriate, increase volume of the fuel tank and, if necessary, set cooler; 4. Due to high oil viscosity, increasing friction within fever, should select the lowest viscosity hydraulic oil;5. When the tubing is too slender and bent, the oil resistance along the way losses increased temperature rises, should increase diameters, shortening pipe, the oil patency;6. The ambient temperature is too high to enable temperature rises, to the use of insulation materials and sounding board so that the system and isolated from the outside world; 7. Prolonged unnecessarily high pressure oil from the relief valve to the fuel tank, temperature rises, should be improved circuit design, variable pump or unloading measures 7 The adverse consequences of air to invade the hydraulic system and solutions The adverse consequences of air to intrusion hydraulic system are : 151. To enable the oil has some compression, resulting system to produce the noise, Vibration and movement caused parts of crawling and undermines the work of a smooth;2. Oxidation of the oil easily degenerate lower oil life. Solution : (1) The air from the tank into the system more opportunities, such as the fuel tank inadequate; hydraulic pump oil absorption tube penetrated oil is too short; Range pipe and tubing back to the fuel tank too close or middle distance with no partitions separating; Oil back spatter, stirs bubble; Pump inhaled air; no tubing inserted to the fuel tank so that the oil out of oil to surface and the wall, in the oil surface will produce large bubble of air inhaled together with the oil system. Therefore, the oil-tank to keep sufficient height; Range pipe and tubing should be back at the minimum guaranteed under the oil surface, Taken with clapboard separated; (2) Since sealing leakage or pipe joint of hydraulic components and the adjoining plane where the fixing screw tight, Air from these areas will be invasive; System below atmospheric pressure, such as the absorption of pump cavity, Range pipe and tubing pressure oil flow rate is high (low pressure) local area; stop working in the system, system to the oil-oil pipeline returned to the return of the fuel tank, will be partial vacuum in the region, In these regions the most easily penetrated the air. Therefore, in order to try to prevent the pressure throughout below atmospheric pressure; Seal all components should use a good seal, pipe joints and the adjoining plane Department should tighten the screws; Regular cleaning pump oil absorption mouth of filters, to prevent oil absorption resistance increased while oil dissolved in the air out of free access to the system;(3) On the main hydraulic equipment, hydraulic cylinder with the best exhaust devices to exclude the air system. 8. System flow shortage and the reasons for a solution 1. Because of inadequate flows of hydraulic pumps, System result of inadequate flows, the hydraulic pump parts should check whether there are defects, in a timely manner to replace or repair damaged pieces of ultra-poor; If inhaled air pump affect the flow of hydraulic pumps, would take measures prevent air inhaled, the variable pump as variable sector adversely affected the flow pump, variable response agenci