【正文】 planetary reduction gears, steering gear, hydraulic control valve, hydraulic system, hydrostatic transmission, hydraulic Casting. pneumatic control valve, cylinder, gas processing triple pieces, mechanical seals, rubber and seal products more than 50 production enterprises, attracting foreign investment over 200 million . dollars. the current situation Profiles After 40 years of efforts, China hydraulic, pneumatic and sealing industry has formed a relatively plete categories. a certain level of technical capacity and the industrial system. According to the 1995 Third National Industrial Census statistics, hydraulic, Pneumatic seals and industrial 370,000 annual sales ine of 100 million yuan in stateowned, villagerun, private and cooperative enterprises, individual, three capital enterprises with a total of more than 1,300, of which about 700 hydraulic, Pneumatic seals and the approximately 300 thousand. By 1996 with the international trade statistics, the total output value of China39。s growth stage for the rapid development stage. Which, hydraulic industry in the early 1950s from the machine tool industry production of fake Sugrinder, broaching machine, copying lathe, and other hydraulic drive started, Hydraulic Components from the plant hydraulic machine shop, selfoccupied. After entering the 1960s, the application of hydraulic technology from the machine gradually extended to the agricultural machinery and mechanical engineering fields, attached to the original velocity of hydraulic shop some stand out as pieces of hydraulic professional production. To the late 1960s, early 1970s, with the development of mechanized production, especially in the second automobile factory in providing efficient, automated equipment, along with the Hydraulic Components manufacturing has experienced rapid development of the situation, a group of SMEs have bee professional hydraulic parts factory. 1968 China39。s and 70 for specialized production system 。 distribution of a full range of electrical control. Hydraulic Station principle : motor driven pump rotation, which pump oil absorption from the oil tank. to mechanical energy into hydraulic pressure to the station, hydraulic oil through Manifold (or valve binations) realized the direction, pressure, After adjusting flow pipe and external to the cylinder hydraulic machinery or motor oil, so as to control the direction of the motive fluid transformation force the size and speed the pace of promoting the various acting hydraulic machinery. A development course China Hydraulic (including hydraulic, the same below), pneumatic and seals industrial development process can be broadly divided into three phases, namely : 20 early 1950s to the early 1960s, the initial stage。2008 楊曙東 何存興主編[2] 現(xiàn)代工程圖學(xué)[M].湖南科學(xué)技術(shù)出版社。參考文獻(xiàn)[1] 液壓傳動(dòng)與氣壓傳動(dòng)[M]。系統(tǒng)中采用流量放大器，使裝載機(jī)轉(zhuǎn)向更加靈活、準(zhǔn)確。轉(zhuǎn)向機(jī)構(gòu)液壓系統(tǒng)采用方向盤轉(zhuǎn)向，運(yùn)用人機(jī)學(xué)，使駕駛室的布置更為合理，便于操縱。系統(tǒng)設(shè)有過載保護(hù)和吸空補(bǔ)油回路，很好的保護(hù)了系統(tǒng)中的各元件。由于液壓行走系統(tǒng)壓力損失和溫升很大，所以目前的裝載機(jī)的行走系統(tǒng)很少采用液壓，參考的東西比較少，所以在元件的選擇上，具有一定的盲目性。系統(tǒng)設(shè)有補(bǔ)油和熱交換回路、主泵回零及制動(dòng)回路、補(bǔ)油回路和壓力保護(hù)回路，很好的增加了元件的耐用性。本設(shè)計(jì)完成了5全液壓輪式裝載機(jī)液壓系統(tǒng)的設(shè)計(jì)——直動(dòng)式溢流閥的設(shè)計(jì)，主要內(nèi)容包括：液壓系統(tǒng)圖的擬定，元件的計(jì)算和選擇，系統(tǒng)的壓力損失計(jì)算和溫升計(jì)算，非標(biāo)件直動(dòng)式溢流閥和動(dòng)臂液壓缸的設(shè)計(jì)計(jì)算。為保證穩(wěn)定性，＜=＜，采用兩端固定。則 ==取有效圈數(shù)=，取支承圈=，則總?cè)?shù) =+=14圈： 彈簧的幾何尺寸名稱代號(hào)單位計(jì)算方法或公式及其結(jié)果材料直徑彈簧中徑16彈簧內(nèi)徑==彈簧外徑=16+=有效圈數(shù)壓縮彈簧的支承圈數(shù)總?cè)?shù)=+=14節(jié)距=（～）=～8，取=6間距==自有高度=+=74壓縮彈簧高徑比==螺旋角（176。即有 ≥==根據(jù)GB135，取=,與原假設(shè)吻合。彈簧鋼絲直徑由彈簧直徑和彈簧中經(jīng)計(jì)算其旋繞比 ==查得其曲度系數(shù)=。查表得其許用切應(yīng)力===855。即有 = = 彈簧的設(shè)計(jì)計(jì)算選擇材料和許用切應(yīng)力根據(jù)彈簧的工作條件，屬Ⅲ類載荷彈簧，選用碳素彈簧鋼絲。即有 = =確定彈簧的剛度因 （517）故 = =應(yīng)該注意，這里的預(yù)壓縮量是指閥口剛關(guān)閉時(shí)的數(shù)值，故包括了滑閥的封油產(chǎn)度。）， =69176。額定開度計(jì)算 （514）式中： ——額定壓力（）； ——閥芯直徑（）； ——油液密度； ——閥口流量系數(shù)，=。直動(dòng)式溢流閥的其他尺寸按結(jié)構(gòu)要求定。閥體沉割直徑、沉割寬度按經(jīng)驗(yàn)取 =+（～） =30+（1～15） =31～45 取 =40按結(jié)構(gòu)確定，應(yīng)保證進(jìn)出油口直徑的要求。如果節(jié)流孔太大或太短，則節(jié)流作用不夠，將使閥的啟閉特性變差，而且工作中會(huì)出現(xiàn)較大的壓力振擺；反之，如果節(jié)流孔太小或太長，則閥的動(dòng)作會(huì)不穩(wěn)定，壓力超調(diào)量也會(huì)加大。即 ==取 =16閥芯的直徑：按經(jīng)驗(yàn)取 ～） =（～）16 =8～取 =13閥芯活塞直徑：按經(jīng)驗(yàn)取 =（～） =（～）13 =～取 =30對(duì)閥的靜態(tài)特性影響很大，按上式選取時(shí)，對(duì)額定流量小的閥選較大的值。 直動(dòng)式溢流閥 設(shè)計(jì)要求額定壓力=；額定流量為先導(dǎo)泵的出口流量，其=。 直動(dòng)式溢流閥的設(shè)計(jì)，壓力油從進(jìn)油口進(jìn)入閥后，經(jīng)過阻尼孔作用在閥芯底下，閥芯的底面上受到油壓的作用形成一個(gè)向上的液壓力?；钊麠U與活塞肩部壓應(yīng)力驗(yàn)算 （512）式中： ——活塞桿直徑（），=； ——活塞上的鉆孔直徑（）， ——作用于活塞上的工作壓力()； ——活塞上鉆孔的倒角尺寸()，==； ——許用壓應(yīng)力()，活塞材料采用耐磨鑄鐵（A3），則=即有： ==53694活塞桿危險(xiǎn)斷面處的合成應(yīng)力（考慮近似等于活塞桿退刀槽處的拉應(yīng)力）： （511）式中：——活塞桿拉力（）； ——活塞桿危險(xiǎn)斷面處的直徑（），查表得：=49；——系數(shù)，可取=；——許用應(yīng)力（），活塞桿采用調(diào)質(zhì)強(qiáng)度HB=240～270的40鋼，=400。：==110+210=130==110+10=120 缸體與缸底焊接即有： ===＜=105符合條件。=1139823=341946=＞=341946，符合條件。 細(xì)長＞時(shí)： （55） 細(xì)長≤時(shí): （56）式中： ——活塞桿的計(jì)算長度（），查表得：取兩端鉸接，=930； ——活塞桿橫截面積回轉(zhuǎn)半徑（），===20； ——活塞桿橫截面積轉(zhuǎn)動(dòng)慣量（），===2009600； ——活塞桿橫截面積（），===5024； ——柔性系數(shù)，對(duì)鋼取=85； ——端蓋安裝形式系數(shù)，查表得：=1； ——材料彈性模數(shù)（），對(duì)鋼=206； ——材料強(qiáng)度實(shí)驗(yàn)值（），對(duì)鋼≈490； ——系數(shù)，對(duì)鋼取?？v向彎曲極限力計(jì)算 液壓缸受縱向力以后，產(chǎn)生軸線彎曲，當(dāng)縱向力達(dá)到極限力以后，缸產(chǎn)生縱向彎曲，出現(xiàn)不穩(wěn)定現(xiàn)象。則 ≥==取==10，==＜=，為薄壁鋼筒。 ==6＜＜9 ；符合條件。 液壓缸的作用能力、作用時(shí)間及儲(chǔ)油量的計(jì)算，當(dāng)向有桿腔供油時(shí)，活塞桿向內(nèi)收進(jìn)時(shí)的拉力為： 雙作用液壓缸 （51）式中：——活塞桿直徑（）； ——缸內(nèi)徑（）； ——工作壓力（）； ——液壓缸機(jī)械效率，一般取=。當(dāng)左端進(jìn)油時(shí)活塞桿伸出，動(dòng)臂舉升；當(dāng)右端進(jìn)油時(shí)，動(dòng)臂下降；當(dāng)兩端都與油箱連通時(shí)，動(dòng)臂浮動(dòng)。 ==