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附錄A
液壓系統(tǒng)
液壓系統(tǒng)是利用液體為介質(zhì)把能量從動力源傳遞到消耗位置的動力傳遞系統(tǒng)。所有液壓系統(tǒng)原理都基于帕斯卡定律，是以發(fā)現(xiàn)這個定律的帕斯卡的名字而命名的。這個定律表明在一個密封的容器里，如缸體或管子，受壓液體向容器表面所有方向施加相等的力。
在實際液壓系統(tǒng)中，帕斯卡定律解釋從系統(tǒng)中得到的各種結(jié)果。泵使流體在系統(tǒng)里流動。泵的吸入口接到液壓油容器，通常稱為液壓油箱。大氣壓壓在油箱里液體上，使液體流入泵里。當液壓泵工作時，它以適當?shù)膲毫Π岩后w從油箱壓到管道里。
泵排出的高壓液體由閥控制。多數(shù)液壓系統(tǒng)運用三種控制方式：（1）流體壓力控制；（2）流體速度控制；（3）流體方向控制。
在液壓系統(tǒng)中由泵排出的液體經(jīng)由控制閥到液壓馬達。液壓馬達利用受壓的流體作為它的能量源產(chǎn)生旋轉(zhuǎn)的力和運動。液壓馬達跟泵的結(jié)構(gòu)類似，只不過它的工作原理是相反的。
在要求直線運動代替旋轉(zhuǎn)運動的地方是用液壓缸，它由運動活塞和缸體構(gòu)成。當活塞由高壓流體驅(qū)動時，活塞桿傳遞力，推動負載移動一段設(shè)定的距離。
當液壓缸中的活塞運動受阻時，例如當活塞有負載，在液壓缸中必然會產(chǎn)生一個相應(yīng)的壓力?；钊娣e以平方英寸為單位，受壓液體的壓力乘以活塞面積，就等于在活塞桿的末端產(chǎn)生的一個以磅為單位的輸出力。
活塞桿的速度取決于受壓液體進入液壓缸里的多少?？梢钥刂朴鸵毫魅缫簤焊椎钠渲幸欢耍诨钊麠U上產(chǎn)生一個拉力或產(chǎn)生一個推力。在活塞上有密封裝置，防止流體的泄漏。
活塞的方向控制取決于流體進入液壓缸的哪一端，當高壓流體進入液壓缸的一端時，流體一定從另一端流出。排出的流體又回液壓油箱。在利用空氣的氣動系統(tǒng)里，空氣是由缸體排放入大氣中的。
方向控制閥也稱作二通閥、三通閥和四通閥等等，是根據(jù)它們的基本功能命名的。壓力控制閥和簡單的節(jié)流閥，通常采用二通閥，他們僅有通和斷功能。三通閥可以有幾種功能,這些和三通閥的油口有關(guān)。例如，來自泵的高壓流體可能傳送到拖拉機的液壓系統(tǒng)里驅(qū)動負載。在不需驅(qū)動時，三通閥將高壓流體送到驅(qū)動輸送機構(gòu)的液壓馬達上。
也可以用三通閥來控制單作用式液壓缸（只能單方面施力）的運動。例如，當三通閥通時，它可以阻止高壓流體流入液壓缸。同時，該閥可以把液壓缸中的液體導向液壓油箱，因此，柱塞缸可以在重力或回程彈簧的作用下回到它的初始位置。
四通閥有四個油口。壓力油口控制流體連接到需要高壓的地方。同時有一個油口從高壓區(qū)排出油液。排出的液體流回液壓油箱。
在液壓系統(tǒng)中，受壓液體的運動類似于電力系統(tǒng)中的電流的運動。在電力系統(tǒng)里，通過電流運動來完成工作，液壓系統(tǒng)也類似。
在直流電力系統(tǒng)中，執(zhí)行機構(gòu)的速度可以通過改變流入執(zhí)行元件的電流來改變。在交流電力系統(tǒng)中通過調(diào)節(jié)相位獲得速度控制。液壓系統(tǒng)中可通過不同控制方式來調(diào)節(jié)速度。氣動系統(tǒng)由于氣體的彈性改變，只可以得到相對粗略的速度控制。
在液壓系統(tǒng)中，我們可以對泵進行設(shè)計，以便利用泵的變量機構(gòu)來改變所輸出的高壓液體的流量，從而使液壓馬達或其它裝置獲得不同速度。利用泵出口管道的節(jié)流調(diào)節(jié)，可以按在直流電力系統(tǒng)相似的原理來控制液體流動。在需要時，液壓系統(tǒng)可以利用閥來改變液體流向不同通道，獲得速度控制。
液壓流體的壓縮性是很小的。但是，如果必要的話，這種微小的壓縮性可用來吸收由于微小的機械擾動而引起的系統(tǒng)壓力變化。因為應(yīng)用于系統(tǒng)的空氣或氣體有彈性，氣動系統(tǒng)有這個能力。液壓系統(tǒng)可以用一個或多個具有壓縮氣體的蓄能器，在液體中快速調(diào)節(jié)壓力。
利用重力、彈力和壓縮氣體可以為液壓系統(tǒng)蓄能。重力經(jīng)常用來輔助使其返回原來的位置，而不需要借助液力。這種輔助形式簡化了相應(yīng)部分液壓系統(tǒng)。
在液壓系統(tǒng)中壓力容易控制?？刂茐毫Φ闹饕绞绞钱斶_到需要的壓力時，在泵和管道里設(shè)置一個裝置來減少液體。泵只需提供足夠的液體，補充系統(tǒng)中泄漏。在氣動系統(tǒng)利用壓力調(diào)節(jié)閥使壓力源保持一定的壓力值。
在電氣系統(tǒng)中，通常通過改變電動機轉(zhuǎn)向來獲得方向控制。在液壓系統(tǒng)或氣動系統(tǒng)里，方向控制閥可以變換流柱的位置，從而獲得方向的改變。液壓系統(tǒng)可設(shè)計出來，如果需要泵可以反轉(zhuǎn)。
泵用機械密封措施，目前的機械密封泵，在一種產(chǎn)品的應(yīng)用極為廣泛， 但和節(jié)約能源，隨著生產(chǎn)技術(shù)水平提高的要求， 機械密封的應(yīng)用前景更為廣泛。 機械密封的密封效果將直接影響整個機器運動，尤其是在石油化工領(lǐng)域， 因為會存在易燃，易爆，易揮發(fā)，以猛烈有毒等介質(zhì)中的傳播。 機械密封會出現(xiàn)泄漏，將嚴重影響生產(chǎn)的正常進行， 嚴重的是還出現(xiàn)了一些重大的安全事故。 人們在分析質(zhì)量故障原因，往往是熟悉的機械密封自身方面查找原因， 例如:機械密封的塑造是否合適，材料選擇是否正確， 包裝表面相比印刷機是否正確，擦副的選擇是否合理等等。 但總之是非常的機械密封的外部條件方面去查找原因，例如: 泵的機械密封創(chuàng)造的條件是否合適，伺服系統(tǒng)的配置是否適當， 但這些方面的原因往往是算多。
筆者從抽水分析，合理的措施與機械密封的外部條件的角度影響 密封效果的幾種因素和應(yīng)采取的對策。 1原則，并要求機械密封過: 機械密封是靠一對相對運動的連接器端面(固定，肛 有行健連同軸)的相互擬合形式的小軸向發(fā)揮起到密封作用，噻 收盤這種設(shè)備被稱為機械密封。 機械密封通常由動環(huán)，靜聯(lián)系，合同的部分和密封部分組成。 動作的連接和靜態(tài)連接端面作曲一副對碰， 動作的連接依賴于庭密封液體的壓力，導致其承擔的 靜態(tài)連接端面， 并制作兩個環(huán)節(jié)端面合適相比印刷機和維持一個極薄液膜實現(xiàn) 密封的目標。 合同部分施壓，可能會造成泵工作狀態(tài)下，也保持端面擬合， 保證密封介質(zhì)不外泄露，并防止雜質(zhì)進入密封端面。 密封部分發(fā)揮密封動議環(huán)節(jié)和差距軸二， 靜態(tài)鏈接和腺體峽三作用，同時對振動泵，攻擊的緩沖作用。 機械密封在實際的運動并不是一個孤立的部分， 它是與其他零件，水泵結(jié)合在一起運動，同時還可以看到，通過其基本原則， 機械密封正常運行的條件，比如: 否則逃離措施泵主軸的是不能很大， 附屬摩擦端面不能形成比例壓力，要求定期; 泵主軸，機械密封夸贊不能有界線非常大撓度 端面等待一分鐘，否則比壓力將不平衡。 此外，只有滿足類似這樣的外部條件，優(yōu)良的機械密封過自己的功能，能達到理想的密封效果。 2分析原因，外部條件的影響:
泵主軸軸向逃離寬度大: 密封，機械密封客需要有一定比例的壓力面對面，收盤 該院能力起著到達密封作用，二 五，規(guī)定春天，機械密封產(chǎn)需有一定的壓縮量眼下，政學院的一個推力封堵端面，住宅使得密封產(chǎn)生的壓力，封堵了什么是比例要求面對面會談。 為確保這是一個比較的壓力， 數(shù)額機械封鎖規(guī)定該泵主軸不能有非常大逃亡 要確保在0.5毫米以上。 設(shè)計中，但在現(xiàn)實中，由于不合理的設(shè)計，有時候 非常大逃亡泵主軸創(chuàng)建措施，查封機器非常不利。 這種現(xiàn)象有時出現(xiàn)在多級離心泵，特別是在這個過程中的泵啟動，外逃數(shù)額比較大。 自動化變化的B平衡一套平衡軸向差距響時，平衡板工程 變化差異平衡壓力檢查前后兩個側(cè)面，因此， 制作人，來平衡軸向力軸向力相反方向的作用力。 慣性效應(yīng)移動自肩逃離和瞬態(tài)泵工況波動 肩輪動不會動，在一些一軸平衡國家逃離所有時間 在侍從動議。 但數(shù)額軸平衡，以逃避檢查，在做好經(jīng)常性工作，只有有0105 ~ 011毫米， 滿足許可軸向逃離，機械密封測量過015毫米的要求， 允許機械密封軸向逃離平衡軸向逃離衡量可能性撿到齒輪， 當停車器，工作條件的巨大變革，使泵輪環(huán)的期望。 泵后，經(jīng)過長時間運動 摩擦平衡一套平衡和一枚戒指磨損掉，二峽增強隨后， 數(shù)額封堵軸向逃離增加機器不斷推向前進。 效果，因為軸向力，密封密實軟以及粉吸吮平仄加辛苦， 密封都穿效應(yīng)加劇的情況下，查封，直至完全密封損壞， 失去面子背對面對工作面機械吐痰列平仄封鎖， 是磨損與平衡板的， 轉(zhuǎn)子軸組件逃離措施數(shù)額封堵軸向逃離要求比， 部隊封堵密實柔軟和粉被打了折扣， 不能達到的效果封堵要求， 使機械密封兩邊的所有水泵，最終失去密封。
軸向力的影響是很大的: 機械密封可以承受軸向力的，在過程中使用的，存在封住軸向力。 由于水泵軸方面的原因，如理性，制造，裝配， 正在投入使用，動態(tài)平衡的組織設(shè)計， 帶來的軸向力是不均衡以外密封具有軸向力 密封壓蓋溫度將部分高度時，動輪， 以中聚丙烯類似，在高溫下才能夠融解下來， 泵開始發(fā)熱因此很快馬上失去密封效果， 連續(xù)涌水封堵端面則出現(xiàn)遺漏的現(xiàn)象時，泵的動靜。
水泵軸的撓度都換成大:機械密封來電端面密封，這是一種旋轉(zhuǎn)軸接觸式動作密封，它是在流體介質(zhì)和彈性元件的作用，兩個達到密封效果，因此，在堅持小側(cè)門，相對快速而激烈軸中心線密封端面革命 要求必須接受一支清一色的兩密封機械吐痰列平仄封存折扣，是磨損與平衡板的， 轉(zhuǎn)子軸組件逃離措施數(shù)額封堵軸向逃離要求比， 部隊封堵密實柔軟和粉被打了折扣， 不能達到的效果封堵要求， 使機械密封兩邊的所有水泵，最終失去密封。
不協(xié)助灌溉系統(tǒng)或協(xié)助灌溉系統(tǒng)插木樁合理: 到協(xié)助，機械密封沖洗過的制度是非常重要的是，它能保護作用，例如查封面對，去冷卻，潤滑，是 興走雜物。 設(shè)計，可協(xié)助分配灌溉系統(tǒng)， 無法達到密封效果不理性有時; 外國物質(zhì)有時雖然設(shè)計，人事已設(shè)計輔助系統(tǒng)，因為在洗滌液，流量，壓力，沖洗液不足， 洗口的位置，設(shè)計等原因，不合理，同樣也不能達到密封效果。
振動大斜:機械密封振動過堅持過大，最終失去密封作用。 該機械密封過大傾斜振動原因有時不是機器封住自己的事業(yè)，但其他泵組成部分，是制作起源振動， 等待事業(yè)，如果泵的設(shè)計主軸事業(yè)，軸承精度不合理， 加工不足，聯(lián)軸器度差，徑向力同等級別的大。
事業(yè)的水泵汽蝕:該功能不是很好， 泵的旋轉(zhuǎn)速度，是局部的高度由于裝置系統(tǒng)操作不合理以及泵入口汽蝕， 該汽蝕， 汽蝕入部分發(fā)生在水泵一天打來明天發(fā)生后， 能有氣泡的水， 這5鎊機器一方面封住外表面軟粉， 使得它的表面損傷出現(xiàn); 另一個方面可能作出恰如其分所包圍，也含有氣泡流軟 粉膜，不能形成穩(wěn)定的流動膜， 帶來的干摩擦，裝修，所包圍的面，使機械密封損壞。 機床工作精度不夠:機床加工精度不夠，原因有很多， 治療的準確性具有豐富的機械密封自客是不夠的， 這方面的原因認定，也容易注意容易引起人們。 但有時是泵其它成分治療缺乏準確度，這方面的原因， 不重視容易引起人們。 比如:事業(yè)如泵主軸，軸套，泵體， 準確性缺乏封堵擴腔體。 密封作用，這些原因的存在，封住機器非常不利。
回應(yīng)措施采取: 泵主軸逃來衡量大措施: 金額設(shè)計，軸向力平衡配備，消除軸向逃離理性。為滿足這一要求，其中有兩對多級離心泵，比較理想的設(shè)計方案: 一個是平衡盤加軸向停止推軸承 平衡軸向力從平衡板， 開展對軸泵主軸軸向從停止推軸承位置限制; 另一個是平衡鼓加軸向停止推軸承 軸向力平衡以外的主要部分，從平衡鼓 剩余軸向力熊從停車推軸承 軸停止推軸承進行軸向?qū)λ弥鬏S在同一時間位置的限制。 第二類計劃的關(guān)鍵是設(shè)計平衡鼓，合理 這使得可以平衡以外的大部分軸向力真的。 等待一個產(chǎn)品開泵其它單級泵，在數(shù)額范圍封鎖范圍的要求 在機械設(shè)計中采用逃離幾個措施保證水泵軸幡招魂。消除大軸力損害的措施:組織設(shè)計軸向動態(tài)中的平衡，合理 這使得可以走平衡軸向力確實充分， 被封存的，完全由機器創(chuàng)造了有利條件。 要實現(xiàn)檢驗檢測，發(fā)現(xiàn)問題，解決一個問題，以前的產(chǎn)品， 半成品出廠到重要領(lǐng)域，如小電廠，石化， 適用。 有些重要的泵可以設(shè)計一個軸向測力環(huán)的肩， 監(jiān)測，隨時對正在邁向力量大小條幅， 發(fā)現(xiàn)問題及時解決。消除偏見大泵主軸偏轉(zhuǎn)措施: 存在這一現(xiàn)象主要是多級離心泵臥式，需要采取以下措施設(shè)計時間: ( 1 )削減兩端距離軸軸承。 水泵葉輪級數(shù)不是非常多， 根據(jù)一般的水泵揚程的要求，是比較好的情況下，嘗試自己最佳的改善，每級葉輪揚程， 削減級數(shù); ( 2 )增加泵主軸直徑。 期間的直徑設(shè)計泵主軸，考慮大小移交權(quán)力單純只 不，但想的慣性因素，如載荷， 徑向力以為機器封住，軸偏轉(zhuǎn)，從方法和連接。 多一點設(shè)計，沒有充分認識到了這一點; ( 3 )提高泵主軸材料系; ( 4 )泵主軸設(shè)計后，即將完成，釷 電子偏轉(zhuǎn)對泵主軸要求退房開展的核心，學校秘密計劃表示反對。 上升協(xié)助灌溉系統(tǒng):的情況下，條件允許的話，系統(tǒng)設(shè)計輔助灌溉，以充分發(fā)揮。 沖洗壓力一般要求0208 ~ 011兆帕對開密封腔壓力， 如果輸送介質(zhì)屬于易汽化，對01175 ~ 012兆帕高于汽化壓力。 壓力封堵一空腔前往秘密計劃對根據(jù)每種泵的結(jié)構(gòu) 過去的因素，如格局， 系統(tǒng)當軸封口音的壓力是非常高的壓力時，用水幾乎逼近應(yīng)當封存完全 最大極限， 發(fā)熱，也有可能使軸封液體必須遷離面積圍封腔吸引 液體到低氣壓，拿走了摩擦。 如果灌水量作為推薦用藥帶出冷是什么1所示。 根據(jù)每種泵的操作條件，部署管道及配件理性。 如果冷卻器，孔板，過濾器，閥門，流量指標，測壓， 溫度等。 可靠性和壽命查封完全事實上，依靠分配封堵輔助系統(tǒng)的一個極大的影響。清除措施，泵入口汽蝕: ( 1 )汽蝕功能，提高了泵是臥式，筆 他蒸氣滿足現(xiàn)場裝置侵蝕的功能要求; ( 2 )現(xiàn)場測試的要求，需要和水泵汽蝕功能水平的匹配; ( 3 )現(xiàn)場安裝和工況調(diào)整需要給水泵創(chuàng)造有利條件。清除措施，泵甩頭: ( 1 )該產(chǎn)品是嘗到了泵在設(shè)計過程中，是去分析振動源充分，以消除振動源 ; ( 2 )泵產(chǎn)品的制造裝配過程中，指令規(guī)則去進行， 消除振動源，嚴格按標準和操作; ( 3 )泵，電機， 協(xié)助設(shè)備可前往把關(guān)， 嚴格杜絕撼源期間現(xiàn)場安裝等基地，現(xiàn)場管道; ( 4 )認真把關(guān)，杜絕在生產(chǎn)，處理，保存現(xiàn)場修理，調(diào)整，收盤明擺的一個來源。執(zhí)行的信設(shè)計標準: 設(shè)計封堵產(chǎn)品的要求泵產(chǎn)品設(shè)計和機器進行相關(guān)的國內(nèi)外收盤手動，四企業(yè)家，也應(yīng)進行仔細標準的過程中的產(chǎn)品設(shè)計，其中每一個深地帶具體內(nèi)容收盤 耗理解一個標準，工藝標準的要求內(nèi)容，是實施旨在向現(xiàn)在，一進口材有許多標準設(shè)計，不明白，去執(zhí)行新的標準，氮催產(chǎn)素，但被復制的經(jīng)驗，按照設(shè)計的一套舊沖板和老年人失明收盤明。 這使出法術(shù)，以提高我國產(chǎn)品技術(shù)水平和進入國際市場是十分不利的。 完善規(guī)范認知，可以說，機械工業(yè)設(shè)計，需要解決問題的迫切目前。
當泵的設(shè)計與機械密封不僅要考慮機械密封本身的影響因素， 此外，必須考慮外觀的機械密封每一種影響因素。必須注意以下幾個問題，在實際工作中: ( 1 )泵產(chǎn)品在設(shè)計過程中已充分考慮到泵其它零部件以及一種 收盤現(xiàn)場其它設(shè)備對機械密封的使用效果的影響，創(chuàng)造了良好的外部條件，為機械密封; ( 2 )增加對機械密封的伺服系統(tǒng)的重要作用的認識，磷 背面的圓滿盡可能機械密封的伺服系統(tǒng)，提高了密封效果; ( 3 )對重要泵產(chǎn)品的機械密封，要增加保護措施，提高密封質(zhì)量，住宅 得出了密封質(zhì)量事故; ( 4 )分析機械密封的質(zhì)量事故的原因，小探傷充分考慮到泵的其它零部件的機械密封運動的影響，筆 阿克措施不斷提高機械密封的效果。 螺栓泵，因人而變運輸， 自吸引能力等特點強，有可能成為糟糕的是， 能夠運輸?shù)囊后w含有固體顆粒，在污水處理廠，可投入使用，涵蓋廣泛的領(lǐng)域中的毒品傾角輸送水，濕污泥和絮凝劑。 螺栓泵的選擇和使用應(yīng)遵循經(jīng)濟，合理，可靠的原則。 如果這樣想不是出在該領(lǐng)域的知識型設(shè)計選曲，可以分配給以下管理，保持帶來不便，有必要根據(jù)生產(chǎn)實際，因此選擇和使用， 現(xiàn)在，合理可靠的螺栓泵能誓娩跟進計劃 并沒有一帆風順，降低修補成本。
附錄B
HYDRAULIC SYSTEM
Hydraulic systems are power-transmitting assemblies employing pressurized liquid to transmit energy from an energy-generating source to an energy-use area. All hydraulic systems depend on Pascal’s law, named after Blaise Pascal, who discovered the law. This law states that pressurized fluid within a closed container-such as cylinder or pipe-exerts equal force on all of the surfaces of the container.
In actual hydraulic systems, Pascal’s law defines the basis of the results which are obtained from the system. Thus, a pump moves the liquid in the system. The intake of the pumps connected to a liquid source, usually called the tank or reservoir. Atmospheric pressure, pressing on the liquid in the reservoir, forces the liquid into the pump. When the pump operates, it forces liquid from the tank into the discharge pipe at a suitable pressure.
The flow of the pressurized liquid discharged by the pump is controlled by valves. Three control functions are used in most hydraulic systems: (1) control of the liquid pressure, (2) control of the liquid flow rate, and (3) control of the direction of flow of the liquid.
The liquid discharged by the pump in a fluid-power system is directed by valves to a hydraulic motor. A hydraulic motor develops rotary force and motion, using the pressurized liquid as its energy source. Many hydraulic motors are similar to pumps, except that the motor operates in a reverse manner from a pump.
Where linear instead of rotary motion is desired, a cylindrical tube fitted with a movable piston, called a hydraulic cylinder, is often used. When the piston is moved by the pressurized fluid, the piston rod imparts a force or moves an object through a desired distance.
Restricting the movement of the piston in a hydraulic cylinder, as when the piston carries a load, creates a specific pressure relationship within the cylinder. The surface area of the piston face is said to contain a specific number of square inches. The pressure of the pressurized liquid, multiplied by the piton area, produces an output force, measured in pound, at the end of the piston rod.
The speed of movement of the piston rod depends on how fast the pressurized fluid enters the cylinder. Flow into the cylinder can be directed to either end, producing either a pushing or pulling force at the piston rod end. A seal around the rod where it passes through the cylinder end prevents leakage of the liquid.
Directional control of the piston depends on which end of cylinder the liquid enters. As pressurized liquid enters one end of the cylinder, liquid must be drained from the other end. The drained liquid is led back to the reservoir. In a pneumatic system using air, the air in the exhausting end of the cylinder is vented to the atmosphere.
Directional-control valves, also called two-way, three-way, four-way, etc. , are named in accordance with their basic function. Pressure-control and simple restrictor valves are usually two-way valves. They provide ON or OFF service. A three-way valves may perform several functions, all associated with the three-ports in the valve. For example, the power or pressurized liquid from a pump in a tractor may be sent to the hydraulic system serving the tractor’s front-end loader. Or the three-way valve may send the pressurized liquid to a hydraulic motor driving a feed conveyor while the front-end loader is not being used.
Three-way valves may also be used to direct pressurized fluid to a single-acting hydraulic cylinder. As the three-way valve is actuated (operated) it can stop the pressurized flow to the cylinder. Further, the same valve can divert liquid from the cylinder to the reservoir, so the cylinder can retract by gravity or return springs and assume its original position.
A four-way valve has four ports or openings. The pressure port directs fluid flow to an area where pressurized liquid is desired. One of the other ports can simultaneously drain liquid from a pressurized area. The dram liquid can be directed to the reservoir.
In a fluid-power system, the movement of pressurized fluid resembles the action of electric current in an electrical system. In such a system, electrical energy is continually moving when work is being done. The same is true of a fluid-power system.
In a direct-current electrical system, the speed of a device is varied by changing the flow of current to the device. Alternating-current system, use phase shifting to attain similar speed control. Hydraulic system can obtain infinite speed variations by several methods of control, Pneumatic systems, because of the springiness of the gas, have relatively crude speed control.
In fluid-power systems, the pump can be designed so the discharge flow of the pressurized liquid can be varied by manipulating the pump mechanism, giving varying speeds of the hydraulic motor or other output device. A restriction un the pump outlet can limit the fluid in a manner similar to that used in a direct-current electrical system. Where desired, hydraulic systems can be designed to use valves which divert flow to different flow channels to give the desired speed control.
The compressibility of hydraulic fluid is slight. But, if desired, this slight compressibility can be used to absorb small, erratic machine movements which cause pressure variations in a fluid-power system. Pneumatic systems have this capability inherently because of the springiness of the air or gas used in the system. Hydraulic systems may use one or more accumulators-devices which contain pressurized gas which can accommodate rapid pressure changes in the fluid portion of the system.
Gravity, springs and compressed gases provide potential energy I many hydraulic systems. Thus, gravity assist is often used to return a part to its original position without the use of power from the hydraulic system. This type of assistance also simplifies the parts in the hydraulic system.
Pumps Mechanical seal Measures.At present the mechanical seal in pumps in a kind of product the application extremely widespread, but and will save the energy along with the product technical level enhancement the request, the mechanical seal application prospect is more widespread. The mechanical seal seal effect directly will affect the entire machine movement, in particular in petroleum chemical industry domain, because will exist flammable, explosive, is easy to volatilize, to be violently poisonous and so on the medium.
? The mechanical seal appears will divulge, seriously will affect the production normally to carry on, is serious also appears the significant security accident. People when analysis quality breakdown reason, often is familiar with in the mechanical seal own aspect searches the reason, for example: Mechanical seal shaping whether appropriate, choice of material whether correct, the packing surface compared to presses whether correctly, rubs the vice- choice is whether reasonable and so on. But is short very much in the mechanical seal external condition aspect searches the reason, for example: Pumps for the mechanical seal creation condition whether appropriate, the servosystem disposition is whether appropriate, but these aspects reasons often are count for much.
This article author from pumped has analyzed the reasonable measure with the mechanical seal external condition angle which the influence seal effect several kind of factors and should adopt.1 Principle and request that machinery seals off:The mechanical seal is depends on a pair of relative motion link end surface A (fixed, another revolves together with axis) the mutual fitting forms the small axial play plays the seal role, this kind of equipment is called the mechanical seal. The mechanical seal usually by moves the link, the static link, contracts the part and the seal part is composed. Moves the link and the static link end surface composes a pair to rub, moves the link to depend on in the sealed chamber the liquid pressure to cause its shoulder up on the static link end surface, and produces on two links end surfaces suitable compared to presses and maintains an extremely thin liquid membrane to achieve the seal the goal. Contracts the part pressurize, may cause to pump under the operating condition, also maintains the end surface fitting, guaranteed the seal medium nothing more than leaks, and prevented the impurity enters seals the end surface. Seals the part to play the seal to move the link and axis gap B, the static link and the gland gap C role, simultaneously to the vibration which pumps, attacks the cushioning effect. The mechanical seal in the actual movement is not an isolated part, it is with other spare parts which pumps combines the movement together, simultaneously may see through its basic principle, the mechanical seal normal operation has the condition, for instance: Otherwise fleeing measures a pump spindle's being not able to very big, friction subsidiary end face can not form the ratio pressure demanding regularly; The pump spindle that machinery hermetic sealing gets along can not have boundary very big deflection , end face waits a minute otherwise than pressure will be uneven. Besides only when satisfying similar such external condition, fine machinery seals off oneself function, ability reaches ideal hermetic sealing effect.2 Analysis of causes that external condition affects:
Pump spindle axial to fleeing is measured big: The hermetic sealing that machinery seals off needs to have certain ratio pressure face to face, such ability plays arrive at hermetic sealing role, be requiring that spring that machinery seals off needs to have certain compression amounts right now, give a propulsive force sealing off end face, rotating makes hermetic sealing produce the pressure sealing off the what be demanded ratio face to face. For ensuring that this one is compared to pressure, the amounts machinery is sealed off requiring that the pump spindle can not have very big fleeing, need to ensure that within 0.5 mm in general. Design but middle in reality, unreasonable because of design, that sometimes, very big fleeing of pump spindle creation measure , seal off to machinery sigmatism is very disadvantageous. This phenomenon sometimes appears in multi-level centrifugal pump, Especially in the process of pump starting.The automation changes the b balancing a set and balancing the axial gap between the ring when balance plate works , changes the difference balancing the pressure checking front and back two flanks thereby , produces one and comes to balance the axial force axial contrary force direction acting force. The inertia effect moving since the rotator flees and transient pump working condition fluctuation, the rotator moving round will not be motionless in some one axial balance location.Balance the state fleeing all the time in retinue to move. But the amounts balancing axial to fleeing in checking in regular job only have 0105 ~ 011 mm , satisfy permission axial to fleeing that machinery seals off measuring 015 mm requests, allowable machinery hermetic sealing axial to fleeing balancing axial to fleeing to measure possibility getting it in gear, when stopping machine , working condition great change in pump making rings round expects that.After pumps passes through the long time movement, the friction balancing a set and balancing a ring wears away , gap b enhances subsequently, the amounts sealing off axial to fleeing increase machinery unceasingly. Effect because of axial force, hermetic sealing compacting soft and floury sucking oblique tones in increases by strenuously , hermetic sealing wears the effect aggravating , sealing up completely until hermetic sealing damages , loses face to face away face to face.The machinery spitting out oblique tones is sealed off , is wear away with balancing plate's, rotator component axial to fleeing measures the amounts sealing off axial to fleeing demanding greater than , the force sealing off compacting soft and floury is diminished , cannot reach the effect sealing off a request , making the machinery hermetic sealing on both side of the pump all ultimately losing hermetic sealing.
The axial force is prejudiced big: Machinery hermetic sealing can bear the axial force's in the process of usage, if the effect that existence seals off axial the force , to machinery is grave. Since pump axial the aspect cause such as rational and making , assembling , being put into use that dynamic balance organization designs, brings about the axial force be not balanced away sometimes.Machinery hermetic sealing bears a axial force , the seal gland temperature will be partial to height when moving round, to the medium that polypropylene is similar to, before the high temperature be able to be molten down, the pump starts the queen therefore losing hermetic sealing effect very quickly right away , discontinuous gushing sealing off end face then appearing leaves out phenomenon when the pump is motionless.
pump spindles deflections are slanting big: That machinery hermetic sealing calls end face hermetic sealing, is that one kind of axis of rotation to contact-type moves hermetic sealing , it is under fluid medium and elasticity component effect , two perpendicularities reach hermetic sealing effect thereby in stick the small side door , relative rapid and intense axle centre line hermetic sealing end face revolution, demands to need to accept a force homogeneously between two hermetic sealing therefore.The machinery spitting out oblique tones is sealed off , is wear away with balancing plate's, rotator component axia