電大液壓氣動技術(shù)課程作業(yè)解答(四)小抄參考

1、專業(yè)好文檔液壓氣動技術(shù)課程作業(yè)解答（四）一、填空題1. 按工作原理不同，空氣壓縮機可分為_ _和_兩種。2. 單位質(zhì)量的氣體體積稱為氣體的_。3. 在等容過程中，氣體的壓力與_成正比，氣體對外作功等于_。4. 為保證氣動系統(tǒng)正常工作，需要在_ _處安裝后冷卻器，以析出水蒸氣，并在 _ _處安裝油水分離器，進一步清除空氣中的水分。5. 濕空氣的水蒸汽分壓為0.025mpa，干空氣分壓為0.08mpa，相對濕度為50%，則濕空氣的壓力為_，同溫度下飽和水蒸氣的壓力為_。6. 氣動缸所耗壓縮氣體量等于_ _、_ _和_ _的乘積，一般情況下，計算氣動缸耗氣量時，還應(yīng)把耗壓縮氣體量換算為_ _。7.

2、在氣動缸的速度控制回路中，常使用由_和_并聯(lián)組合而成的流量控制閥。對于雙作用氣動缸，為避免氣動缸的爬行，應(yīng)采用_方式進行調(diào)速。8.在氣動系統(tǒng)中，按工作原理和使用范圍不同，調(diào)壓閥可分為_和_兩種。1容積式 速度式2比容3絕對溫度 零4壓縮機出口 后冷卻器出口50.105mpa 0.05mpa6活塞面積 行程長度 每分鐘往復(fù)次數(shù) 耗自由氣體量7單向閥 節(jié)流閥 排氣節(jié)流8直動式調(diào)壓閥 先導(dǎo)式調(diào)壓閥二 、判斷題1等溫過程中，氣體與外界無熱量交換，故氣體的內(nèi)能保持不變。（）注：等溫過程是指氣體在溫度保持不變的條件下從一個狀態(tài)變化到另一個狀態(tài)的過程，由于溫度不變所以氣體內(nèi)能保持不變，而并非與外界無熱量交換

3、，氣體與外界無熱量交換的過程是絕熱過程。2. 氣動缸的無負載工作特性要求氣動缸空載時在限定壓力下平穩(wěn)運行無爬行現(xiàn)象。（）注：氣動缸的無負載工作特性是指在無負載條件下進行實驗時，使氣動缸能產(chǎn)生動作的最低工作壓力，這個壓力是使活塞低速運動、不產(chǎn)生爬行的極限壓力。3. 緩沖氣動缸是依靠彈簧的平衡力使活塞運動速度減慢，實現(xiàn)緩沖作用的。（）注：從緩沖氣動缸的結(jié)構(gòu)可知，緩沖氣動缸是利用空氣被壓縮、吸收運動部件的動能而實現(xiàn)緩沖作用的。4. 先導(dǎo)式安全閥用壓縮空氣的氣壓作為控制信號，其先導(dǎo)閥是一個調(diào)壓閥。（）注：由先導(dǎo)閥調(diào)整后的壓縮空氣作為控制信號，通過控制口導(dǎo)入主閥內(nèi)，以代替直動式彈簧控制安全閥。5. 油水

4、分離器的作用是分離潤滑油中的水分雜質(zhì)，再經(jīng)油霧器使氣動系統(tǒng)中的氣動元件得到潤滑。（）注：油水分類器的作用是分離壓縮空氣中凝結(jié)成水分和油分的雜質(zhì)，使壓縮空氣得到初步凈化。三 、計算題1. 絕對壓力為0.5 mpa，溫度為30ºc的空氣，絕熱膨脹到大氣壓時，求其膨脹后的空氣溫度。解：由氣體狀態(tài)方程 和可得 （1）再由絕熱過程的氣體狀態(tài)方程 可得 （2）（2）代入（1）得 所以 式中：t127330303k p10.5mpa p20.1013mpa 絕熱指數(shù)k1.4代入計算 即膨脹后氣體溫度為81。2設(shè)濕空氣的壓力為0.1013 mpa，溫度為20ºc，相對濕度為50%，求：（1

5、）絕對濕度；（2）含濕量；（3）氣溫降低到多少度時開始結(jié)露（露點）。解：查表105，可得壓力為0.1013 mpa、溫度為20ºc條件下，濕空氣中飽和水蒸氣分壓力為pb0.0023mpa，飽和水蒸氣的密度為17.3g/m3。（1）絕對濕度濕空氣中飽和水蒸氣的密度即飽和濕空氣的絕對濕度 xb17.3g/m3由相對濕度為50%可得濕空氣的絕對濕度 xxb×50%8.65 g/m3（2）含濕量由pb0.0023mpa得 濕空氣分壓 ps pb×50%=0.00115 mpa干空氣分壓 pgpps0.10130.001150.10015 mpa空氣的含濕量 （3）露點當(dāng)濕

6、空氣飽和，即相對濕度為100時，由pspb=0.00115 mpa查表可得露點為9。3. 如圖所示汽缸吊（吊取重物的氣動缸），氣源壓力為0.5 mpa，起吊物體重量為fw=900n，活塞返回由活塞、活塞桿自重返回，自重fz=100n，活塞桿直徑為d=20mm，機械效率=0.8，安全系數(shù)n=1.5，試確定氣動缸內(nèi)徑d。 解：氣缸吊為拉力作功，其拉力為式中：f（fwfz）n(900100) ×1.51500n p0.5 mpa0.5×106pa =0.8d20mm0.02m代入計算 取標(biāo)準(zhǔn)值 d80mm。4. 一單出桿雙作用氣動缸，內(nèi)徑為50mm，活塞桿直徑為20mm，行程為3

7、00mm，每分鐘往復(fù)運動10次，使用壓力為0.6 mpa，試求其耗氣量。解：活塞面積 耗壓縮空氣量 耗自由空氣量 winger tuivasa-sheck, who scored two tries in the kiwis' 20-18 semi-final win over england, has been passed fit after a lower-leg injury, while slater has been named at full-back but is still recovering from a knee injury aggravated agains

8、t usa.both sides boast 100% records heading into the encounter but australia have not conceded a try since josh charnley's effort in their first pool match against england on the opening day.aussie winger jarryd hayne is the competition's top try scorer with nine, closely followed by tuivasa

9、-sheck with eight.but it is recently named rugby league international federation player of the year sonny bill williams who has attracted the most interest in the tournament so far.the kiwi - with a tournament high 17 offloads - has the chance of becoming the first player to win the world cup in bot

10、h rugby league and rugby union after triumphing with the all blacks in 2011."i'd give every award back in a heartbeat just to get across the line this weekend," said williams.the (lack of) air up there watch mcayman islands-based webb, the head of fifa's anti-racism taskforce, is i

11、n london for the football association's 150th anniversary celebrations and will attend city's premier league match at chelsea on sunday."i am going to be at the match tomorrow and i have asked to meet yaya toure," he told bbc sport."for me it's about how he felt and i woul

12、d like to speak to him first to find out what his experience was."uefa has opened disciplinary proceedings against cska for the "racist behaviour of their fans" during city's 2-1 win.michel platini, president of european football's governing body, has also order

13、ed an immediate investigation into the referee's actions.cska said they were "surprised and disappointed" by toure's complaint. in a statement the russian side added: "we found no racist insults from fans of cska." baumgartner the disappointing news: mission aborted.the s

14、upersonic descent could happen as early as sunda.the weather plays an important role in this mission. starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. the balloon, with capsule attached, will move through the

15、lower level of the atmosphere (the troposphere) where our day-to-day weather lives. it will climb higher than the tip of mount everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. as he cro

16、sses the boundary layer (called the tropopause),e can expect a lot of turbulence.the balloon will slowly drift to the edge of space at 120,000 feet ( then, i would assume, he will slowly step out onto something resembling an olympic diving platform.they blew it in 2008 when they got caught cold in t

17、he final and they will not make the same mistake against the kiwis in manchester.five years ago they cruised through to the final and so far history has repeated itself here - the last try they conceded was scored by england's josh charnley in the opening game of the tournament.that could be cla

18、ssed as a weakness, a team under-cooked - but i have been impressed by the kangaroos' focus in their games since then.they have been concentrating on the sort of stuff that wins you tough, even contests - strong defence, especially on their own goal-line, completing sets and a good kick-chase. they've been great at all the unglamorous stuff that often goes unnoticed in the stands bu