电大液压与气动技术期末考试答案小抄参考.doc

专业好文档成都市技师学院20092010学年度（上期）液压与气动技术期末考试_系_ _专业_班 姓名_学号_题号一二三四五总分一 填空题（每空 1 分，共 20 分）1、液压与气压传动是以 流体 为工作介质进行能量的 传递 和 控制 的一种传动形式。2、液压油的粘度随液压油的温度和压力而变，当压力增大时，液压油粘度 增大 ；当液压油温度升高时，液压油的粘度 降低 。3、液压与气压传动系统由 能源装置 、 执行装置 、 控制装置 和辅助元件四个部分组成。4、液压缸的作用是将 压力能 转变为直线运动或摆动的 机械能 是液压传动系统中的执行元件。5、液压泵是一种 能源 装置，它将机械能转换为 压力能 是液压传动系统中的动力元件。6、溢流阀通常并接在液压泵的出口，用来保证液压系统的出口压力恒定时称为 定压阀 ；用来限制系统压力的最大值称为 安全阀 ；还可以在执行元件不工作时使液压泵 卸载 。7、在结构上，所有液压阀都是由 阀芯 、 阀体 和 驱动阀芯动作的元器件 组成。8、液压阀按照用途可分为 方向控制阀 、 压力控制阀 和 流量控制阀 三大类。二 判断题（每题2分，共20分）1、在液压系统中液压缸和马达都可以作为执行装置。 （ ）2、一般液压油的密度为900kg/m3。 （ ）3、液压系统的流量等于横截面积与流体平均速度的乘积，与工作压力无关。（ ）4、液压马达是液压系统中的能源装置。 （ × ）5、液压系统执行元件运动速度较高时，宜选粘度大的液压油。 （ × ）6、减压阀的阀口常闭，溢流阀的阀口常开。 （ ×）7、各类液压阀在工作原理上都是通过改变阀芯与阀体的相对位置来控制和调节 液流的压力、流量及流动方向。 （ ）8、当液控单向阀的控制口K处无压力油通入时，它的工作和普通单向阀一样。 （ ） 9、流量控制阀是通过改变阀口的大小，改变液阻，实现流量调节的阀。（ ）10、节流阀的刚性差，只适用于执行元件工作负载不大且对速度稳定性要求不高的场合。 （）三、单项选择题（每题2分，共20分）1、 选择液压用油首先要考虑的是（ C ）问题。A液压系统的工作压力 B运动速度 C 粘度问题 D环境温度2、广泛应用于龙门刨床、拉床、液压机、工程机械、矿山冶金机械、船舶上液 压泵是（ C ）。A齿轮泵 B叶片泵C柱塞泵 D螺杆泵3、常用于送料和转位装置、液压机械手以及间歇进给机构等辅助运动的是（ B）A活塞式液压缸 B摆动式液压缸C柱塞式液压缸 D伸缩液压缸4、当单杆活塞缸的（C）时，活塞的运动速度最快。A压力油进入无杆腔 B压力油进入有杆腔C左右两腔同时通入压力油（差动连接）5、下列液压泵不能调节流量的是（ C ）。A轴向柱塞泵 B径向柱塞泵C 齿轮泵 D 单作用叶片泵6、以下控制阀图形符号那一个是直动式溢流阀( A )7、能够使油口P和T通，油口A、B封闭，液压泵卸载，液压缸两腔闭锁的滑阀中位机能是（ D ）。A、O型 B、H型 C、Y型 D、M型 8、（ B）在常态时，阀口是常开的，进、出油口相通。A 溢流阀； B减压阀； C顺序阀9、应用最广的减压阀类型是（ A ）。A 定值减压阀； B定差减压阀； C定比减压阀10、与溢流阀的图形符号和动作原理相同的是（B）。A、内控外泄顺序阀 B、内控内泄顺序阀 C、外控外泄顺序阀 D、外控内泄顺序阀四、问答题（每题10分，共20分）、液压系统由哪四部分组成？各部分的作用是什么？答：能源装置：把机械能转换为流体压力能的装置执行装置：把流体的压力能装换位机械能输出控制装置：对系统中流体的压力、流量和流动方向进行控制或调解的装置，以进行信号转换、逻辑运算和放大等功能的信号控制元件辅助元件：保证系统的正常工作所需的其它装置2、液压泵完成吸油和压油的基本条件是什么？液压泵在液压系统中的工作压力取决于什么？ 答： 必须具备可变化的密封容积、吸油腔和压油腔隔开、有与密封容积变化相协调的配油装置及吸油腔与油箱大气相通这四个条件。 工作压力取决于外负载五、计算题（本题分、B两题，任选一题来做，题18分，B题20分）题：画出下列元件的职能符号双向变量液压泵单杆活塞缸普通单向阀三位四通电磁换向阀溢流阀直动式减压阀内控外泄顺序阀可调节流阀B题：已知如图所示的单活塞杆液压缸，活塞内径D100mm，活塞杆直径为d50mm，工作压力p12Mpa，流量q110L/min，回油被压力p20.5Mpa。试求：活塞往返运动时的推力和运动速度？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 against 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-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 both 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 in 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 would 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 ordered 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 supersonic 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 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 crosses 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 the 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 classed 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 but not by your team-mates.It is as though their entire tournament has been preparation for the final.In Johnathan Thurston, Cooper Cronk, Cameron Smith and either Billy Slater or Greg Inglis at full-back they have a spine that is unmatched in rugby league. They have played in so many high-pressure games - a priceless asset going into Saturday.The Kiwis are a lot less experienced but winning a dramatic match like their semi-final against England will do wonders for their confidence.They defeated Australia in the Four Nations final in 2010 and the last World Cup, and know they can rise to the big occasion.