2020年电大液压与气动技术期末必备复习题及答案必考重点.doc

精选电大液压与气动技术复习题考试小抄一、 填空:1、一个完整的液压系统由 、 、 、 和工作介质五部分组成。2、液压泵是_ _元件。是把原动机输入的_ _转变成_ _输出的装置。按结构分为_ _泵，_ _泵和_ _泵。3、 液压缸是_ _元件，是把通过回路输入的_ _转变为_ _输出的装置。能实现差动连接的液压缸是_ _ 液压缸。可以提高_ _ 。4、 管路内液流的压力损失有_ 压力损失和_ 压力损失。75、 液体的流动状态有_ 和_ 。当ReRe为_ ，当ReRe为_ 。在液压传动系统设计中，为使其能量损失小，应使其能量在管道中为_ _ 状态。6、 伯努利方程是_ 在流体力学中的应用。理想液体的伯努利方程中的三项分别是_能，_能和_ 能，三者之和是一个常数。7液压传动是利用液体的 能的传动；液压传动的过程是将 进行转换和传递的过程。8某压力容器表压力为0.3Mpa，则压力容器的绝对压力为_Mpa。（大气压力为0. 1Mpa）9液压马达是 元件，输入的是压力油，输出的是 。10排气装置应设在液压缸 位置。11液压泵的理论流量 实际流量（大于、小于、等于）。12调速阀可使速度稳定，是因为其节流阀前后的压力差 。13在液压技术中，压力与流量的乘积即为 。14液压泵的理论流量是 和 的乘积。15将既无 又 的假想液体称为理想液体。16重力作用下静止液体的等压面是一族 面。17溢流阀能使其 压力保持恒定，减压阀能使其 压力保持恒定。二、选择：1、液压缸是_元件。 A动力 B执行 C控制 2、溢流阀是_。 A执行元件 B压力控制阀 C流量控制阀3、小孔的长径比L/d0.5属于_。A薄壁孔 B细长孔 C短孔4、仪表所测压力是_。 A绝对压力 B相对压力 C大气压力5、双作用叶片泵是_。 A定量泵 B变量泵 C都不是6、下面哪一种三位阀的中位机能可以实现卸荷，_。A B C 7右职能符号表示的液压元件是_。A 先导型溢流阀 B先导型减压阀 C先导型顺序阀 D 直动型顺序阀8右图中，溢流阀的作用是_。A 作溢流阀用 B作安全阀用 C 作卸荷阀用 D作背压阀用9、不属于容积调速回路的是_。A变量泵和液压缸组成的容积调速回路 B定量泵和液压缸组成的容积调速回路 C定量泵和变量马达组成的容积调速回路D变量泵和变量马达组成的容积调速回路10、便于实现压力控制的节流调速回路是_。A进油路节流调速回路 B回油路节流调速回路 C旁油路节流调速回路11、液压锁指的是_。A普通单向阀 B液控单向阀 C换向阀12、在结构上存在困油现象的液压泵的是_。A齿轮泵 B叶片泵 C柱塞泵13、CB-B型齿轮泵中泄漏的途径有有三条，其中_对容积效率影响最大。A 齿轮端面间隙 B 齿顶间隙 C 齿轮径向间隙 14. 圆管中液流的流动状态的表达式即雷诺数为 ( )。 A B C 15定值溢流阀可保持_稳定。A 阀前压力 B 阀后压力 C 泵前、后压差 D 泵出口流量16调速阀是通过调节_来调节执行机构运动速度。A 油泵流量 B 执行机构排油量 C 执行机构供油压力 D 油马达进油量17液压系统油箱内设隔板是为了： A 增强刚度 B 减轻油面晃动 C 防止油漏光 D 利于散热和分离杂质18.液压系统中，当雷诺数RR（临界雷诺数）时为_。A 层流 B 紊流 C 顺流 D 逆流19如右图所示为二级调压回路，阀3调定值与阀1调定值相比_。A 前者大于后者 B后者大于前者 C 两个一样大 D 无特殊要求20最适用于系统短期需要大流量场合快速回路是_。A液压缸差动连接快速回路 B双泵供油快速回路C增速缸快速回路 D用蓄能器的快速回路21、下图为用顺序阀实现压力控制的顺序回路，执行机构液压缸的活塞动作先后顺序是： A B C D 22真空度的计算式为_。A真空度大气压力绝对压力 B真空度绝对压力大气压力C真空度大气压力绝对压力 D真空度绝对压力表压力23大流量的液压系统中，主换向阀应采用_换向阀。A 电磁 B 电液 C 手动 D 机动24差动液压缸，若使其往返速度相等，则活塞面积应为活塞杆面积的_。A 1倍 B 2倍 C D 4 25液压泵吸油口通常安装过滤器，其额定流量应为液压泵流量的_倍。A 1 B 0.5 C 2 D 326、液体在圆管中作层流运动时，液体在圆管轴线上的流速与在圆管管壁附近的流速相比：A 前者大 B 后者大 C 一样大 D 无法判断27为了使齿轮泵的齿轮平稳地啮合运转、吸压油腔严格地密封以及均匀连续地供油，必须使齿轮啮合的重叠系数r_1。A大于 B等于 C小于 D A或B28、解决齿轮泵困油现象的最常用方法是_。 A 减少转速 B 开卸荷槽 C 加大吸油口 D 降低气体温度 29斜盘式轴向柱塞泵改变流量是靠改变_。A 转速 B 油缸体摆角 C 浮动环偏心距 D 斜盘倾角30液压马达的总效率通常等于： A 容积效率×机械效率 B 容积效率×水力效率C 水力效率×机械效率 D容积效率×机械效率×水力效率31能实现差动连接的油缸是： A 双活塞杆液压缸 B 单活塞杆液压缸C 柱塞式液压缸 D 摆动缸32在液压系统中，不能作背压阀的元件是_。A 溢流阀 B 减压阀 C 顺序阀 D 单向阀33节流阀的节流阀口应尽量做成_式。A 薄壁孔 B 短孔 C 细长孔 D AC34液压系统中冷却器一般安装在： A 油泵出口管路上 B 回油管路上C 补油管路上 D 无特殊要求35在油箱中，溢流阀的回油口应_泵的吸油口。A 远离 B 靠近 C 平行于 D 无特殊要求36下列_液压油泵属于变量的是：A 齿轮泵 B 单作用叶片泵 C 双作用叶片泵 D B+C37液压缸的运行速度主要取决于： A 液压缸的密封 B 输入流量C 泵的供油压力 D外负荷三、判断 1、液压马达是动力元件( ) 2、齿轮泵是变量泵( ) 3、安装在压油管路上的过路器是为了保护液压泵( )4、溢流阀是流量控制阀( )5、真空度-相对压力( )6液体中任何一点的压力、速度都不随时间变化，则液体作恒定流动。（ ）7单作用式和双作用式叶片泵都可以做变量泵。（ ）8单杆活塞式液压缸的差动连接可以提高活塞的运动速度，并使其输出推力增大。（ ）9液控单向阀与普通单向阀一样，允许油液沿一个方向流动，不允许反向倒流。（ ）10液压马达的实际输入流量大于理论流量。（ ）11单活塞缸靠液压油能实现两个方向的运动。（ ）12装在液压泵吸油口处的过滤器通常比装在压油口处的过滤精度高。（ ）13.液压缸是执行元件。( )四、名词解释 （1）、理想液体 （2）、恒定流动 （3）、粘温特性 （4）、液压冲击（5）、困油现象 （6）、 绝对压力 （7）、 额定压力 五、计算题1在左图的单杆液压缸中，已知缸体内径D=100mm，活塞杆直径d=70mm，活塞向右运动的速度v=0.1m/s。求进入和流出液压缸的流量q1和q2为多少。2如图所示为相互连通的两个液压缸，大缸的直径D=30cm，小缸的直径d=3cm，若在小活塞上加的力F=200N，大活塞能举起重物的重量G为多少？3某液压泵的输出油压p= 10 MPa，转速n= 1450 r/min，排量V= 200 mL/r，容积效率V=0.95，总效率=0.9，求泵的输出功率和电动机的驱动功率。 4如图，连通器中装有水和另一种液体。已知水的密度s =1×10 kg/m，h =60cm，h=75cm，求另一种液体的密度=?5求图示液压缸：（1）产生的推力；（2）速度的大小及运动的方向。六、综合题1、问答题（1）、什么是液体的压力? 压力有哪几种表示方法?（2）、先导式溢流阀中的阻尼小孔起什么作用？是否可以将阻尼小孔加大或堵塞。（3）、在液压系统中为什么要设置背压回路?可以做背压阀的元件有哪些？（4）、蓄能器有什么功用？（5）、在液压系统中，为什么要设置快速运动回路？执行元件要实现快速运动的方法有那些？2、分析题某机床进给回路如下图所示，它可以实现快进工进快退的工作循环。根据此回路的工作原理，填写电磁铁动作表。（电磁铁通电时，在空格中记“” 号；反之，断电记“”号）1、 2、 电磁铁工作环节1YA2YA3YA快进工进快退1、 电磁铁工作环节1YA2YA3YA快进工进快退2、答案一、填空1动力元件 执行元件 控制元件 辅助元件2动力 机械能 液压能_ 齿轮泵 叶片 柱塞3_执行 液压能 机械能_单杆活塞_ 运动速度_4沿程 局部5层流 紊流 层流 紊流 层流6能量守恒定律 压力 位能 动能7压力 机械能8 0、49执行 转矩和转速10两侧面的最高位置11大于12不变13功率14排量 转速15粘性 不可压缩16水平17进口 出口二、 选择1B 2B 3A 4B 5A 6A 7B 8B 9B 10A 11B 12A 13A 14A 15A 16D 17D 18A 19A 20D 21C 22C 23B 24B 25C 26A 27A 28B 29D 30A 31B 32B 33 A 34B 35A 36B 37B三、 判断1× 2× 3× 4× 5 6× 7× 8× 9× 10 11 12× 13四、1理想液体：是一种假想的无黏性不可压缩的液体。2、恒定流动：液体流动时，若液体中任一点处的压力、流速和密度不随时间变化而变化，则称为恒定流动。3粘温特性：液压油的粘度随温度变化的关系。温度升高，液体分子之间内聚力减小，粘度降低。4液压冲击：在液压系统工作过程中，管路中流动的液体往往会因执行部件换向或阀门关闭而突然停止运动，由于液流和运动部件的惯性在系统内会产生很大的压力峰值，这种现象叫液压冲击。5困油现象：为保证齿轮转动的连续和平稳，齿轮泵总有两对轮齿同时处于啮合状态。这两对齿与侧盖之间就形成了一个封闭的空间。随着轮齿的转动，此封闭空间容积会发生由大变小再变大的变化，这就是困油现象。6、绝对压力：以绝对真空为基准所表示的压力。7、额定压力：液压泵在正常工作条件下，按实验标准规定连续运转的最高压力。五、计算题1、解：进入液压缸的流量q1=A=D/4=47.1L/min排出液压缸的流量q2=A2=（Dd）/4=24L/min2、解：根据帕斯卡原理，由外力产生的压力在两缸中的数值应相等。即p=故大活塞能顶起重物的重量G为G=3、（1）求液压泵的输出功率 液压泵输出的实际流量: qV=qVtV=VnV=200×10-3×1450×0.95 =275.5 L/min 液压泵的输出功率: Po=pqV =10×106×275.5×10-3/60=45.9×103 W =45.9kW （2）求驱动泵的电动机功率 驱动泵的电动机功率即泵的输入功率，为 Pi= Po/= 45.9/0.9=51kW 4、解：由等压面的概念知，在同一液体同一水平面的压力应相等，即 P= Pa+gh P= Pa+gh得Pa+gh = Pa+gh 故所求液体的密度为= h/ h=1000×=800kg/m5、解：（1）产生的推力F=Pd/4（2）速度的大小及运动的方向。V=4q/d,向左。六、综合题1、问答（1）什么是液体的压力? 压力有哪几种表示方法? 答：液体单位面积上所受的法向力称为压力，压力的表示有绝对压力和相对压力两种方法。（2）先导式溢流阀中的阻尼小孔起什么作用？是否可以将阻尼小孔加大或堵塞。答：阻尼小孔作用：产生主阀芯动作所需要的压力差，是先导型溢流阀主要工作的关键。如扩大则不能产生足够的压力差，使主阀芯动作；若堵塞，则先导阀失去了对主阀的控制作用。（3）在液压系统中为什么要设置背压回路?可以做背压阀的元件有哪些？答：可以提高执行元件的运动平稳性或减小工作部件运动时的爬行现象。（4）蓄能器有什么功用？（1）作辅助动力源（2）作应急动力源（3）补偿泄漏和保持恒压（4）吸收脉动,降低音（5）吸收液压冲击（5）在液压系统中，为什么要设置快速运动回路？执行元件要实现快速运动的方法有那些？ 答：提高系统工作效率或充分利用功率。差动连接增速回路，双泵供油增速回路，蓄能器增速回路。2、分析（1） 电磁铁工作环节1YA2YA3YA快进+工进+快退+（2） 电磁铁工作环节1YA2YA3YA快进+工进+快退+ 请您删除一下内容，O(_)O谢谢！【China's 10 must-see animations】The Chinese animation industry has seen considerable growth in the last several years. It went through a golden age in the late 1970s and 1980s when successively brilliant animation work was produced. Here are 10 must-see classics from China's animation outpouring that are not to be missed. Let's recall these colorful images that brought the country great joy. Calabash Brothers Calabash Brothers (Chinese: 葫芦娃) is a Chinese animation TV series produced by Shanghai Animation Film Studio. In the 1980s the series was one of the most popular animations in China. It was released at a point when the Chinese animation industry was in a relatively downed state compared to the rest of the international community. Still, the series was translated into 7 different languages. The episodes were produced with a vast amount of paper-cut animations. Black Cat Detective Black Cat Detective (Chinese: 黑猫警长) is a Chinese animation television series produced by the Shanghai Animation Film Studio. It is sometimes known as Mr. Black. The series was originally aired from 1984 to 1987. In June 2006, a rebroadcasting of the original series was announced. Critics bemoan the series' violence, and lack of suitability for children's education. Proponents of the show claim that it is merely for entertainment. Effendi "Effendi", meaning sir and teacher in Turkish, is the respectful name for people who own wisdom and knowledge. The hero's real name was Nasreddin. He was wise and witty and, more importantly, he had the courage to resist the exploitation of noblemen. He was also full of compassion and tried his best to help poor people. Adventure of Shuke and Beita【舒克与贝塔】 Adventure of Shuke and Beita (Chinese: 舒克和贝塔) is a classic animation by Zheng Yuanjie, who is known as King of Fairy Tales in China. Shuke and Beita are two mice who don't want to steal food like other mice. Shuke became a pilot and Beita became a tank driver, and the pair met accidentally and became good friends. Then they befriended a boy named Pipilu. With the help of PiPilu, they co-founded an airline named Shuke Beita Airlines to help other animals. Although there are only 13 episodes in this series, the content is very compact and attractive. The animation shows the preciousness of friendship and how people should be brave when facing difficulties. Even adults recalling this animation today can still feel touched by some scenes. Secrets of the Heavenly Book Secrets of the Heavenly Book, (Chinese: 天书奇谈) also referred to as "Legend of the Sealed Book" or "Tales about the Heavenly Book", was released in 1983. The film was produced with rigorous dubbing and fluid combination of music and vivid animations. The story is based on the classic literature "Ping Yao Zhuan", meaning "The Suppression of the Demons" by Feng Menglong. Yuangong, the deacon, opened the shrine and exposed the holy book to the human world. He carved the book's contents on the stone wall of a white cloud cave in the mountains. He was then punished with guarding the book for life by the jade emperor for breaking heaven's law. In order to pass this holy book to human beings, he would have to get by the antagonist fox. The whole animation is characterized by charming Chinese painting, including pavilions, ancient architecture, rippling streams and crowded markets, which fully demonstrate the unique beauty of China's natural scenery. Pleasant Goat and Big Big Wolf【喜洋洋与灰太狼】 Pleasant Goat and Big Big Wolf (Chinese:喜羊羊与灰太狼) is a Chinese animated television series. The show is about a group of goats living on the Green Pasture, and the story revolves around a clumsy wolf who wants to eat them. It is a popular domestic animation series and has been adapted into movies. Nezha Conquers the Dragon King（Chinese: 哪吒闹海） is an outstanding animation issued by the Ministry of Culture in 1979 and is based on an episode from the Chinese mythological novel "Fengshen Yanyi". A mother gave birth to a ball of flesh shaped like a lotus bud. The father, Li Jing, chopped open the ball, and beautiful boy, Nezha, sprung out. One day, when Nezha was seven years old, he went to the nearby seashore for a swim and killed the third son of the Dragon King who was persecuting local residents. The story primarily revolves around the Dragon King's feud with Nezha over his son's death. Through bravery and wit, Nezha finally broke into the underwater palace and successfully defeated him. The film shows various kinds of attractive sceneries and the traditional culture of China, such as spectacular mountains, elegant sea waves and exquisite ancient Chinese clothes. It has received a variety of awards. Havoc in Heaven The story of Havoc in Heaven（Chinese: 大闹天宫）is based on the earliest chapters of the classic story Journey to the West. The main character is Sun Wukong, aka the Monkey King, who rebels against the Jade Emperor of heaven. The stylized animation and drums and percussion accompaniment used in this film are heavily influenced by Beijing Opera traditions. The name of the movie became a colloquialism in the Chinese language to describe someone making a mess. Regardless that it was an animated film, it still became one of the most influential films in all of Asia. Countless cartoon adaptations that followed have reused the same classic story Journey to the West, yet many consider this 1964 iteration to be the most original, fitting and memorable, The Golden Monkey Defeats a Demon【金猴降妖】 The Golden Monkey Defeats a Demon (Chinese: 金猴降妖), also referred as "The Monkey King Conquers the Demon", is adapted from chapters of the Chinese classics "Journey to the West," or "Monkey" in the Western world. The five-episode animation series tells the story of Monkey King Sun Wukong, who followed Monk Xuan Zang's trip to the West to take the Buddhistic sutra. They met a white bone evil, and the evil transformed human appearances three times to seduce the monk. Twice Monkey King recognized it and brought it down. The monk was unable to recognize the monster and expelled Sun Wukong. Xuan Zang was then captured by the monster. Fortunately Bajie, another apprentice of Xuan Zang, escaped and persuaded the Monkey King to come rescue the monk. Finally, Sun kills the evil and saves Xuan Zang. The outstanding animation has received a variety of awards, including the 6th Hundred Flowers Festival Award and the Chicago International Children's Film Festival Award in 1989. McDull【麦兜】 McDull is a cartoon pig character that was created in Hong Kong by Alice Mak and Brian Tse. Although McDull made his first appearances as a supporting character in the McMug comics, McDull has since become a central character in his own right, attracting a huge following in Hong Kong. The first McDull movie McMug Story My Life as McDull documented his life and the relationship between him and his mother.The McMug Story My Life as McDull is also being translated into French and shown in France. In this version, Mak Bing is the mother of McDull, not his father. -可编辑修改-