外文翻譯液壓傳動系統(tǒng)設(shè)計與計算

1、畢業(yè)設(shè)計(論文)外文資料翻譯系部： 機械工程系 專 業(yè)： 機械工程及自動化 姓 名： 學(xué) 號： (用外文寫)外文出處： tid-25296.html 附 件： 1.外文資料翻譯譯文；2.外文原文。 指導(dǎo)教師評語：此翻譯文章較詳細地介紹了液壓傳動系統(tǒng)的設(shè)計與計算，闡述了從工況分析入手，確定液壓系統(tǒng)主要參數(shù)和如何選擇液壓元件，并對液壓系統(tǒng)的性能進行了示范驗算，翻譯用詞基本準確，文筆也較為通順，具備一定的英語閱讀能力。 簽名： 注：請將該封面與附件裝訂成冊。附件1：外文資料翻譯譯文液壓傳動系統(tǒng)設(shè)計與計算1 明確設(shè)計要求進行工況分析在設(shè)計液壓系統(tǒng)時，首先應(yīng)明確以下問題，并將其作為設(shè)計依據(jù)。主機的用途、

2、工藝過程、總體布局以及對液壓傳動裝置的位置和空間尺寸的要求；主機對液壓系統(tǒng)的性能要求，如自動化程度、調(diào)速范圍、運動平穩(wěn)性、換向定位精度以及對系統(tǒng)的效率、溫升等的要求；液壓系統(tǒng)的工作環(huán)境，如溫度、濕度、振動沖擊以及是否有腐蝕性和易燃物質(zhì)存在等情況。在上述工作的基礎(chǔ)上，應(yīng)對主機進行工況分析，工況分析包括運動分析和動力分析，對復(fù)雜的系統(tǒng)還需編制負載和動作循環(huán)圖，由此了解液壓缸或液壓馬達的負載和速度隨時間變化的規(guī)律，以下對工況分析的內(nèi)容作具體介紹。1.1 運動分析主機的執(zhí)行元件按工藝要求的運動情況，可以用位移循環(huán)圖(lt)，速度循環(huán)圖(vt)，或速度與位移循環(huán)圖表示，由此對運動規(guī)律進行分析。1.1.1

3、 位移循環(huán)圖lt圖1.1為液壓機的液壓缸位移循環(huán)圖，縱坐標l表示活塞位移，橫坐標t表示從活塞啟動到返回原位的時間，曲線斜率表示活塞移動速度。圖1.1 位移循環(huán)圖1.1.2 速度循環(huán)圖vt(或vl) 工程中液壓缸的運動特點可歸納為三種類型。圖1.2為三種類型液壓缸的vt圖，第一種如圖1.2中實線所示，液壓缸開始作勻加速運動，然后勻速運動， 圖1.2 速度循環(huán)圖最后勻減速運動到終點；第二種，液壓缸在總行程的前一半作勻加速運動，在另一半作勻減速運動，且加速度的數(shù)值相等；第三種，液壓缸在總行程的一大半以上以較小的加速度作勻加速運動，然后勻減速至行程終點。vt圖的三條速度曲線，不僅清楚地表明了三種類型液

4、壓缸的運動規(guī)律，也間接地表明了三種工況的動力特性。1.2 動力分析動力分析，是研究機器在工作過程中，其執(zhí)行機構(gòu)的受力情況，對液壓系統(tǒng)而言，就是研究液壓缸或液壓馬達的負載情況。1.2.1 液壓缸的負載及負載循環(huán)圖（1） 液壓缸的負載力計算工作機構(gòu)作直線往復(fù)運動時，液壓缸必須克服的負載由六部分組成： (1.1) 式中：fc為切削阻力；ff為摩擦阻力；fi為慣性阻力；fg為重力；fm為密封阻力；fb為排油阻力。（2） 液壓缸運動循環(huán)各階段的總負載力液壓缸運動循環(huán)各階段的總負載力計算，一般包括啟動加速、快進、工進、快退、減速制動等幾個階段，每個階段的總負載力是有區(qū)別的。 (a) 啟動加速階段：這時液壓

5、缸或活塞處于由靜止到啟動并加速到一定速度，其總負載力包括導(dǎo)軌的摩擦力、密封裝置的摩擦力(按缸的機械效率=0.9計算)、重力和慣性力等項，即： (1.2)(b) 快速階段： (1.3)(c) 工進階段： (1.4) (d) 減速： (1.5)對簡單液壓系統(tǒng)，上述計算過程可簡化。例如采用單定量泵供油，只需計算工進階段的總負載力，若簡單系統(tǒng)采用限壓式變量泵或雙聯(lián)泵供油，則只需計算快速階段和工進階段的總負載力。1.2.2 液壓馬達的負載工作機構(gòu)作旋轉(zhuǎn)運動時，液壓馬達必須克服的外負載為： (1.6)(1) 工作負載力矩me工作負載力矩可能是定值，也可能隨時間變化，應(yīng)根據(jù)機器工作條件進行具體分析。(2)

6、摩擦力矩mf摩擦力矩mf為旋轉(zhuǎn)部件軸頸處的摩擦力矩，其計算公式為： (1.7)式中：g為旋轉(zhuǎn)部件的重量(n)；f為摩擦因數(shù)，啟動時為靜摩擦因數(shù)，啟動后為動摩擦因數(shù)；r為軸頸半徑(m)。(3) 慣性力矩mi慣性力矩mi為旋轉(zhuǎn)部件加速或減速時產(chǎn)生的慣性力矩，其計算公式為： (1.8) 式中：為角加速度(r/s2)；為角速度的變化(r/s)；t為加速或減速時間(s)；j為旋轉(zhuǎn)部件的轉(zhuǎn)動慣量()，。式中：為回轉(zhuǎn)部件的飛輪效應(yīng)()。各種回轉(zhuǎn)體的可查機械設(shè)計手冊。根據(jù)式(1.6)，分別算出液壓馬達在一個工作循環(huán)內(nèi)各階段的負載大小，便可繪制液壓馬達的負載循環(huán)圖。2 確定液壓系統(tǒng)主要參數(shù)2.1 液壓缸的設(shè)計計

7、算2.1.1 初定液壓缸工作壓力 液壓缸工作壓力主要根據(jù)運動循環(huán)各階段中的最大總負載力來確定，此外，還需要考慮以下因素：（1） 各類設(shè)備的不同特點和使用場合（2） 考慮經(jīng)濟和重量因素，壓力選得低，則元件尺寸大，重量重；壓力選得高一些，則元件尺寸小，重量輕，但對元件的制造精度，密封性能要求高。所以，液壓缸的工作壓力的選擇有兩種方式：一是根據(jù)機械類型選；二是根據(jù)切削負載選。如表2.1、表2.2所示。表2.1 按負載選執(zhí)行文件的工作壓力負載/n50005001000010000200002000030000300005000050000工作壓力/mpa0.811.522.5334455表2.2 按機

8、械類型選執(zhí)行文件的工作壓力機械類型機 床農(nóng)業(yè)機械工程機械磨床組合機床龍門刨床拉床工作壓力/mpaa2358810101620322.2 液壓馬達的設(shè)計計算2.2.1 計算液壓馬達排量 液壓馬達排量根據(jù)下式?jīng)Q定： (2.1)式中：t為液壓馬達的負載力矩(n·m)；為液壓馬達進出口壓力差()；為液壓馬達的機械效率，一般齒輪和柱塞馬達取0.90.95，葉片馬達取0.80.9。2.2.2 計算液壓馬達所需流量液壓馬達的最大流量 (2.2)式中：vm為液壓馬達排量(m3/r)；nmax為液壓馬達的最高轉(zhuǎn)速(r/s)。3 液壓元件的選擇3.1 液壓泵的確定與所需功率的計算3.1.1 液壓泵的確定

9、確定液壓泵的最大工作壓力。液壓泵所需工作壓力的確定，主要根據(jù)液壓缸在工作循環(huán)各階段所需最大壓力p1，再加上油泵的出油口到缸進油口處總的壓力損失p，即 (3.1) 包括油液流經(jīng)流量閥和其他元件的局部壓力損失、管路沿程損失等，在系統(tǒng)管路未設(shè)計之前，可根據(jù)同類系統(tǒng)經(jīng)驗估計，一般管路簡單的節(jié)流閥調(diào)速系統(tǒng)為(25)×105pa，用調(diào)速閥及管路復(fù)雜的系統(tǒng)為(515)×105pa，也可只考慮流經(jīng)各控制閥的壓力損失，而將管路系統(tǒng)的沿程損失忽略不計，各閥的額定壓力損失可從液壓元件手冊或產(chǎn)品樣本中查找，也可參照表1.3選取。表3.1 常用中、低壓各類閥的壓力損失(pn)閥名pn(×1

10、05pa)閥名pn (×105pa)閥名pn (×105pa)閥名pn (×105pa)單向閥0.30.5背壓閥38行程閥1.52轉(zhuǎn)閥1.52換向閥1.53節(jié)流閥23順序閥1.53調(diào)速閥353.1.2 確定液壓泵的流量qb泵的流量qb根據(jù)執(zhí)行元件動作循環(huán)所需最大流量qmax和系統(tǒng)的泄漏確定。（1） 多液壓缸同時動作時，液壓泵的流量要大于同時動作的幾個液壓缸(或馬達)所需的最大流量，并應(yīng)考慮系統(tǒng)的泄漏和液壓泵磨損后容積效率的下降，即 (3.2)式中：k為系統(tǒng)泄漏系數(shù)，一般取1.11.3，大流量取小值，小流量取大值；為同時動作的液壓缸(或馬達)的最大總流量(m3/s)

11、。（2） 選擇液壓泵的規(guī)格：根據(jù)上面所計算的最大壓力pb和流量qb，查液壓元件產(chǎn)品樣本，選擇與pb和qb相當?shù)囊簤罕玫囊?guī)格型號。表3.2 液壓泵的總效率液壓泵類型齒輪泵螺桿泵葉片泵柱塞泵總效率0.60.70.650.800.600.750.800.85 按上述功率和泵的轉(zhuǎn)速，可以從產(chǎn)品樣本中選取標準電動機，再進行驗算，使電動機發(fā)出最大功率時，其超載量在允許范圍內(nèi)。3.2 閥類元件的選擇3.2.1 選擇依據(jù)選擇依據(jù)為：額定壓力，最大流量，動作方式，安裝固定方式，壓力損失數(shù)值，工作性能參數(shù)和工作壽命等。3.2.2 選擇閥類元件應(yīng)注意的問題（1） 應(yīng)盡量選用標準定型產(chǎn)品，除非不得已時才自行設(shè)計專用件

12、。（2） 閥類元件的規(guī)格主要根據(jù)流經(jīng)該閥油液的最大壓力和最大流量選取。選擇溢流閥時，應(yīng)按液壓泵的最大流量選?。贿x擇節(jié)流閥和調(diào)速閥時，應(yīng)考慮其最小穩(wěn)定流量滿足機器低速性能的要求。3.3 蓄能器的選擇（1） 蓄能器用于補充液壓泵供油不足時，其有效容積為： (3.3)式中：a為液壓缸有效面積(m2)；l為液壓缸行程(m)；k為液壓缸損失系數(shù)，估算時可取1.2；qb為液壓泵供油流量(m3/s)；t為動作時間(s)。（2） 蓄能器作應(yīng)急能源時，其有效容積為： (3.4)當蓄能器用于吸收脈動緩和液壓沖擊時，應(yīng)將其作為系統(tǒng)中的一個環(huán)節(jié)與其關(guān)聯(lián)部分一起綜合考慮其有效容積。根據(jù)求出的有效容積并考慮其他要求，即可

13、選擇蓄能器的形式。3.4 管道的選擇3.4.1 油管類型的選擇液壓系統(tǒng)中使用的油管分硬管和軟管，選擇的油管應(yīng)有足夠的通流截面和承壓能力，同時，應(yīng)盡量縮短管路，避免急轉(zhuǎn)彎和截面突變。（1） 鋼管：中高壓系統(tǒng)選用無縫鋼管，低壓系統(tǒng)選用焊接鋼管，鋼管價格低，性能好，使用廣泛。（2） 銅管：紫銅管工作壓力在6.510mpa以下，易變曲，便于裝配；黃銅管承受壓力較高，達25mpa，不如紫銅管易彎曲。銅管價格高，抗震能力弱，易使油液氧化，應(yīng)盡量少用，只用于液壓裝置配接不方便的部位。3.4.2 油管尺寸的確定（1） 油管內(nèi)徑d按下式計算：d= (3.5)式中：q為通過油管的最大流量(m3/s)；v為管道內(nèi)允

14、許的流速(m/s)。一般吸油管取0.55(m/s)；壓力油管取2.55(m/s)；回油管取1.52(m/s)。（2） 油管壁厚按下式計算： (3.6)式中：p為管內(nèi)最大工作壓力；n為安全系數(shù)，鋼管p7mpa時，取n=8；p17.5mpa時，取n=6；p17.5mpa時，取n=4。根據(jù)計算出的油管內(nèi)徑和壁厚，查手冊選取標準規(guī)格油管。3.5 油箱的設(shè)計油箱的作用是儲油，散發(fā)油的熱量，沉淀油中雜質(zhì)，逸出油中的氣體。3.5.1 油箱設(shè)計要點（1） 油箱應(yīng)有足夠的容積以滿足散熱，同時其容積應(yīng)保證系統(tǒng)中油液全部流回油箱時不滲出，油液液面不應(yīng)超過油箱高度的80%。（2） 吸箱管和回油管的間距應(yīng)盡量大。（3）

15、 油箱底部應(yīng)有適當斜度，泄油口置于最低處，以便排油。3.6 濾油器的選擇選擇濾油器的依據(jù)有以下幾點：（1） 承載能力：按系統(tǒng)管路工作壓力確定。（2） 過濾精度：按被保護元件的精度要求確定。（3） 通流能力：按通過最大流量確定。（4） 阻力壓降：應(yīng)滿足過濾材料強度與系數(shù)要求。4 液壓系統(tǒng)性能的驗算為了判斷液壓系統(tǒng)的設(shè)計質(zhì)量，需要對系統(tǒng)的壓力損失、發(fā)熱溫升、效率和系統(tǒng)的動態(tài)特性等進行驗算。4.1 管路系統(tǒng)壓力損失的驗算當液壓元件規(guī)格型號和管道尺寸確定之后，就可以較準確的計算系統(tǒng)的壓力損失，壓力損失包括：油液流經(jīng)管道的沿程壓力損失、局部壓力損失和流經(jīng)閥類元件的壓力損失，即： (4.1)系統(tǒng)的調(diào)整壓力

16、： (4.2) 式中：p0為液壓泵的工作壓力或支路的調(diào)整壓力；p1為執(zhí)行件的工作壓力。如果計算出來的比在初選系統(tǒng)工作壓力時粗略選定的壓力損失大得多，應(yīng)該重新調(diào)整有關(guān)元件、輔件的規(guī)格，重新確定管道尺寸。4.2 系統(tǒng)發(fā)熱溫升的驗算系統(tǒng)發(fā)熱來源于系統(tǒng)內(nèi)部的能量損失，如液壓泵和執(zhí)行元件的功率損失、溢流閥的溢流損失、液壓閥及管道的壓力損失等。系統(tǒng)發(fā)熱功率p的計算: (4.3)式中：pb為液壓泵的輸入功率(w)；為液壓泵的總效率。若一個工作循環(huán)中有幾個工序，則可根據(jù)各個工序的發(fā)熱量，求出系統(tǒng)單位時間的平均發(fā)熱量： (4.4)式中：t為工作循環(huán)周期(s)；ti為第i個工序的工作時間(s)；pi為循環(huán)中第i個

17、工序的輸入功率(w)。4.3 系統(tǒng)效率驗算液壓系統(tǒng)的效率是由液壓泵、執(zhí)行元件和液壓回路效率來確定的。液壓回路效率nc一般可用下式計算： (4.5)式中：p1，q1；p2，q2；為每個執(zhí)行元件的工作壓力和流量；pb1，qb1；pb2，qb2為每個液壓泵的供油壓力和流量。液壓系統(tǒng)總效率： (4.6)式中：為液壓泵總效率；為執(zhí)行元件總效率；為回路效率。5 繪制正式工作圖和編寫技術(shù)文件經(jīng)過對液壓系統(tǒng)性能的驗算和必要的修改之后，便可繪制正式工作圖，它包括繪制液壓系統(tǒng)原理圖、系統(tǒng)管路裝配圖和各種非標準元件設(shè)計圖。正式液壓系統(tǒng)原理圖上要標明各液壓元件的型號規(guī)格。對于自動化程度較高的機床，還應(yīng)包括運動部件的運

18、動循環(huán)圖和電磁鐵、壓力繼電器的工作狀態(tài)。5.1 確定液壓系統(tǒng)參數(shù)由工況分析中可知，工進階段的負載力最大，所以，液壓缸的工作壓力按此負載力計算，根據(jù)液壓缸與負載的關(guān)系，選p1=40×105pa。本機床為鉆孔組合機床，為防止鉆通時發(fā)生前沖現(xiàn)象，液壓缸回油腔應(yīng)有背壓，設(shè)背壓p2=6×105pa，為使快進快退速度相等，選用差動油缸，假定快進、快退的回油壓力損失為p=7×105pa。5.2 選擇液壓元件（1） 確定液壓泵的工作壓力。前面已確定液壓缸的最大工作壓力為40×105pa，選取進油管路壓力損失p=8×105pa，其調(diào)整壓力一般比系統(tǒng)最大工作壓力大

19、5×105pa，所以泵的工作壓力pb(4085)×10553×105pa這是高壓小流量泵的工作壓力。液壓缸快退時的工作壓力比快進時大，取其壓力損失p4×105pa，則快退時泵的工作壓力為： pb=(16.44)×10520.4×105pa這是低壓大流量泵的工作壓力。（2） 液壓泵的流量?？爝M時的流量最大，其值為30l/min，最小流量在工進時，其值為0.51l/min，取k1.2，則： qb1.2×0.5×10-3=36l/min由于溢流閥穩(wěn)定工作時的最小溢流量為3l/min，故小泵流量取3.6l/min。根據(jù)以上

20、計算，選用yyb-aa36/6b型雙聯(lián)葉片泵。（3） 確定管道尺寸:根據(jù)工作壓力和流量，按式(3.5)、式(3.6)確定管道內(nèi)徑和壁厚。(從略)（4） 確定油箱容量油箱容量可按經(jīng)驗公式估算，取v(57)q。本例中：v6q6(636)252l有關(guān)系統(tǒng)的性能驗算從略。附件2：外文原文（復(fù)印件）hydraulic actuation system design and computation1 is clear about the design request to carry on the operating mode analysis.when design hydraulic system b

21、elow, first should be clear about the question, and takes it as the design basis.main engine use, technological process, overall layout as well as to hydraulic gear position and spatial size request; the main engine to the hydraulic system performance requirement, like the automaticity, the velocity

22、 modulation scope, the movement stability, the commutation pointing accuracy as well as the request which to the system efficiency, warm promotes; hydraulic system working conditions, like temperature, humidity, vibration impact as well as whether has situation and so on corrosiveness and heat-sensi

23、tive material existence.in in the above work foundation, should carry on the operating mode analysis to the main engine, the operating mode analysis including the movement analysis and the mechanical analysis, also must establish the load and the operating cycle chart to the complex system, from thi

24、s understood the hydraulic cylinder or the oil motor load and the speed change as necessary the rule, below makes the concrete introduction to the operating mode analysis content1.1 movements analysesthe main engine functional element according to the technological requirement movement situation, ma

25、y use the displacement circulation chart (lt), the speed circulation chart (vt), or the speed and the displacement circulation chart indicated, from this carries on the analysis to the movement rule.1.1.1 displacements circulation attempts ltthe chart 1.1 is the hydraulic press hydraulic cylinder mo

26、ves the circulation chart, the y-coordinate l expression piston moves, the x-coordinate t expression starts from the piston to the reposition time, the rate of curve expression movement of plunger speed.chart 1.1 displacements circulation chart1.1.2 speeds circulation chart vt (or vl)in the project

27、the hydraulic cylinder movement characteristic may induce is three kind of types. the chart 1.2 is three kind of types hydraulic cylinders v t chart, the first kind of like chart 1.2 center solid lines show, the hydraulic cylinder starts to make the uniform accelerated motion, then uniform motion, c

28、hart 1.2 speeds circulation chartfinally uniform retarded motion to end point; the second kind, the hydraulic cylinder preceding partly makes the uniform accelerated motion in the overall travelling schedule, in another one partly makes the uniform retarded motion, also the acceleration value is equ

29、al; the third kind, the hydraulic cylinder one most above makes the uniform accelerated motion in the overall travelling schedule by a smaller acceleration, then uniform decelerates to the travelling schedule end point. vt chart three velocity curve, not only clearly has indicated three kind of type

30、s hydraulic cylinders movement rule, also indirectly has indicated three kind of operating modes dynamic performance.1.2 mechanical analyses1.2.1 hydraulic cylinders loads and duty cycle chart(1) hydraulic cylinders load strength computationswhen the operating mechanism makes the straight reciprocat

31、ing motion, the hydraulic cylinder must overcome the load is composed by six parts (1.1)in the formula: fc in order to resistance to cutting; ff in order to friction drag; fi for inertia resistance; fg for gravity; fm in order to seal the resistance; fb in order to drain the oil the resistance.(2 )

32、hydraulic cylinders cycle of motion various stages overall load strengththe hydraulic cylinder cycle of motion various stages overall load strength computation, generally includes the start acceleration, quickly enters, the labor enters, quickly draws back, decelerates applies the brake and so on se

33、veral stages, each stage overall load strength has the difference.(a) starts the acceleration period: by now the hydraulic cylinder or the piston were in from static enough to starts and accelerates to the certain speed, its overall load strength including guide rail friction force, packing assembly

34、 friction force (according to cylinder mechanical efficiency m=0.9 computation), gravity and so on item, namely: (1.2)(b) fast stage: (1.3)(c) the labor enters the stage: （1.4） (d) decelerates: (1.5)to the simple hydraulic system, the above computation process may simplify. for example uses the sing

35、le proportioning pump to supply the oil, only must calculate the labor to enter the stage the overall load strength, if the simple system uses the limiting pressure type variable displacement pump or a pair of association pumps for the oil, then only must calculate the fast stage and the labor enter

36、s the stage the overall load strength.1.2.2 oil motors loadwhen the operating mechanism makes the rotary motion, the oil motor must overcome the outside load is: (1.6)(1) operating duties moment of force me. the operating duty moment of force is possibly a definite value, also possibly as necessary

37、changes, should carry on the concrete analysis according to the machine working condition.(2) friction moments. in order to revolve the part journal place friction moment, its formula is: (1.7)in the formula: g is revolves the part weight (n); f is the rubbing factor, when the start for the factor,

38、after the start for moves the rubbing factor; r is the journal radius (m).(3) moment of inertiami. the moment of inertia which in order to revolve the part acceleration or decelerates when produces, its formula is: (1.8) in the formula: is the angle acceleration (r/s2);is the acceleration or deceler

39、ates the time (s); j is revolves the part rotation inertia (),in the formula: in order to rotate the part the flywheel effect ().each kind may look up <machine design handbook>according to the type (1.6), separately figures out the oil motor in a operating cycle various stages load size, then

40、may draw up the oil motor the duty cycle chart2 determinations hydraulic system main parameter2.1 hydraulic cylinders design calculations2.1.1 initially decides the hydraulic cylinder working pressurein the hydraulic cylinder working pressure main basis cycle of motion various stages biggest overall

41、 load strength determined, in addition below, but also needs to consider the factor:(1) each kind of equipment different characteristic and use situation.(2) considerations economies and the weight factor, the pressure elects lowly, then part size big, the weight is heavy; the pressure chooses high

42、somewhat, then part size small, the weight is light, but to the part manufacture precision, the sealing property requests high.therefore, the hydraulic cylinder working pressure choice has two ways: one, elects according to the mechanical type; two, according to cuts the load to elect.if the table 2

43、.1, the table 2.2 shows.the table 2.1 presses the load to choose the execution file the working pressureload/n50005001000010000200002000030000300005000050000working pressure/mpa0.811.522.5334455the table 2.2 presses the mechanical type to choose the execution file the working pressuremechanical type

44、engine bedfarm machineryproject machinerygrinderaggregate machine-tooldragon gate digs the bedbroaching machineworking pressure/mpaa2358810101620322.2 oil motors design calculation2.2.1 computations oil motor displacementunder oil motor displacement according to the type decided that, (2.1)in the fo

45、rmula: t is the oil motor load moment of force (n·m); for oil motor import and export pressure difference (n/m3);is the oil motor mechanical efficiency, the common gear and the plunger motor takes 0.9 0.95, the leaf blade motor takes 0.8 0.9.2.2.2 computations oil motor needs the current capaci

46、ty oil motor the maximum current capacity (2.2)in the formula: is the oil motor displacement (m3/r); is the oil motor highest rotational speed (r/s).3 hydraulic pressure parts choice3.1 hydraulic pumps determinations with need the power the computation(1) determines the hydraulic pump the biggest wo

47、rking pressure. the hydraulic pressure pumping station must the working pressure determination, mainly acts according to the hydraulic cylinder in the operating cycle various stages to have most tremendous pressure p1, in addition the oil pump loses sigma delta p the oil mouth to the cylinder place

48、always pressurep, namely (3.1) loses, the pipeline including the oil after the flow valve and other parts local pressures along the regulation loss and so on, before system pipeline design, may act according to the similar system experience to estimate, common pipeline simple throttle valve velocity

49、 modulation system p is (2 5) ×105pa, with the velocity modulation valve and pipeline complex system is (5 15) ×105pa, also may only consider flows after various control valves pressure loss, but ignores the circuitry along the regulation loss, various valves rated pressure loses may searc

50、hes from the hydraulic pressure part handbook or the product sample, also may refer to the table 1.3 selectionsthe table 3.1 is commonly used, the low pressure each kind of valve pressure loses (pn)valvepn (×105pa)valvepn (×105pa)valvepn (×105pa)valvepn (×105pa)cone-way valve0.30

51、.5cone-way valve38cone-way valve1.52cone-way valve1.52cross valve1.53cross valve23cross valve1.53cross valve353.1.2 determines the hydraulic pump current capacityqbpumps the current capacity basis functional element operating cycle must the maximum current capacity and the system divulges the determ

52、ination(1) at the same time when more than hydraulic cylinders movement, the hydraulic pump current capacity must be bigger than the maximum current capacity which at the same time the movement several hydraulic cylinders (or motor) needs, and should consider the system divulging wears the volumetri

53、c efficiency drop after the hydraulic pump, namely (3.2)in the formula: k is the system leakage coefficient, generally takes 1.1 1.3, the great current capacity takes the small value, the small current capacity takes the great value; for at the same time movement hydraulic cylinder (or motor) is biggest (m3/s).(2) chooses the hydraulic pump the specification table 3.2 hydraulic pumps overall effec