2014年电大液压气动技术基础期末复习题及答案参考小抄【电大考试必备】(共5页).doc

精选优质文档-倾情为你奉上电大液压气动技术基础期末复习题及答案参考小抄一、填空1液压系统中的两个重要参数是(流量)和(压力)，液压传动是以液体的(压力)能传递动力的。2根据度量基准的不同，液体的压力分为(相对压力)和( 绝对压力)两种，大多数表测得的压力是(相对压力)。3调速阀是由(定差减压)阀和节流阀( 串联)连接而组成。4容积调速基本回路有三种，它们是(变量泵-定量马达)、(变量泵-变量马达)及(复合调速)。5差动回路可以实现油缸的( 快速 )运动，但差动连接时，油缸的推力却明显的( 降低 )。二、选择题1运动速度（ B ）时宜采用粘度较低的液压油减少摩擦损失：工作压力（ ）时宜采用粘度较高的液压油以减少泄漏。A. 高低 B. 高高C. 低高 D. 低低2. 在用一个泵驱动一个执行元件的液压系统中，采用三位四通换向阀使泵卸荷，应选用（ D ）型中位机能 A. “P”型 B. “O”型 C. “Y”型 D. “H”型3限制齿轮泵工作压力提高的主要因素是( C )。(A)存在困油现象 (B)流量脉动 (C)泄漏 (D)径向力不平衡4溢流阀的控制油压来自阀的( A )。(A)进口端 (B)出口端(C)设有单独的泄油油路 (D)没有单独的泄油油路5调速阀是用（B）而成的 A. 节流阀和顺序阀串联 B. 节流阀和定差减压阀串联 C. 节流阀和顺序阀并联 D. 节流阀和定差减压阀并联三、简答题1.液压传动系统由哪几部分组成部分?各组成部分的作用是什么? （答：液压传动系统主要有以下五部分组成：动力元件：液压泵，其功能是将原动机输入的机械能转换成液体的压力能，为系统提供动力。执行元件：液压缸、液压马达，它们的功能是将流体的压力能转换成机械能，输出力和速度（或转矩和转速），以带动负载进行直线运动或旋转运动。控制元件：压力、流量和方向控制阀，它们的作用是控制和调节系统中液体的压力、流量和流动方向，以保证执行元件达到所要求的输出力（或力矩）、运动速度和运动方向。辅助元件：保证系统正常工作所需要的辅助装置，包括管道、管接头、油箱、过滤器和压力计等。工作介质：用以传递动力并起润滑作用。2简述液压冲击产生的原因。在液压系统中，由于某种原因，液体压力在一瞬间会突然升高，产生很高的压力峰值，这种现象称为液压冲击。液压冲击产生的原因：（1）液流通道迅速关闭或液流迅速换向使液流速度的大小或方向突然变化时，由于液流的惯力引起的液压冲击。（2）运动着的工作部件突然制动或换向时，因工作部件的惯性引起的液压冲击。（3）某些液压元件动作失灵或不灵敏，使系统压力升高而引起的液压冲击。3何谓气穴现象？它有哪些危害？通常采取哪些措施防止气穴及气蚀？在液压系统中（或液压元件中）因局部压力降低而有气泡形成的现象称为气穴现象。危害：引起气蚀，产生振动噪声；形成气塞破坏系统正常工作。措施：尽力减少油液中空气的含量，防止气体混入系统；防止系统局部压力过低；在易发生气穴部位采用耐蚀材料及保护镀层。4.说明下图所示双泵双速回路的工作原理，并分析确定阀3、4的调定压力关系？ （1）快速时：低压大流量泵2、高压小流量泵1同时向系统供油；慢速时：高压小流量1向系统供油，低压大流量泵2卸荷（2）阀3的调定压力大于阀4的调定压力四、分析题1.若把先导式溢流阀的远控制口当成泄漏口接油箱，试分析液压系统会产生什么问题产生卸荷现象，系统压力近乎零。2夹紧回路如下图所示，若溢流阀的调整压力p13Mpa、减压阀的调整压力p22Mpa。（1）试分析活塞空载运动时A、B两点的压力各为多少？减压阀的阀芯处于什么状态？（2）工件夹紧，活塞停止运动后，A、B两点的压力又各为多少？此时，减压阀芯又处于什么状态？ 答：（1）活塞空载运动，由于没有负载力作用，系统工作压力为0，不考虑沿程阻力损失，A、B两点压力相等，都是0MPa，此时减压阀处在非工作状态，阀口常开 （2）工件夹紧后，溢流阀工作，此时A点压力为溢流阀调定压力，3MPa，减压阀也开始工作，B点压力为2MPa，减压阀阀芯处于半开状态，保证出口压力恒定在2MPa。五、计算题1 图示的简化回路中，溢流阀的调定压力是2.5×106Pa,系统工作时溢流阀始终有油流回油箱，活塞有效工作面积为0 .1m2,求当负载分别为：F=2×104N；F=0；F=-5×103N时，油缸出口压力P2各为多少？ 解：由于溢流阀始终有油流回油箱，油缸进油腔压力等于溢流阀的调定压力，为2.5×106Pa。油缸两腔的作用力相等，则有：P2×0.1+F=2.5×106×0.1 即有：P22.5×106+ F/0.1当F2×104N时，P22.7×106Pa当F0时，P22.5×106Pa当F5×104N时，P22.55×106Pa2已知液压泵转速为1000r/min，排量为160ml/r，额定压力为30Mpa，实际输出流量为150L/min，泵的总效率为0.87，求：泵的理论流量；泵的容积效率和机械效率；驱动液压泵所需的电动机功率。解：1)泵的理论流量：q=n×V=1000×160=ml/min=160(L/min)2)泵的容积效率：v=q/qt=150/160=0.9375=93.75机械效率：m=/v=0.87/0.9375=0.928=92.8%3) 驱动液压泵所需的电动机功率等于液压泵的输入功率：P=p×qt=30×106×160×10-3=80×103(W)=80(kW) 六、综合题下图所示回路可实行“快进工进快退原位停止和液压泵卸荷”的工作循环，完成电磁铁动作顺序表（通电“”，断电“”） 1YA2YA3YA4YA快 进+-+工 进+-+快 退-+-+原位停止，泵卸荷-_七、综合题某机床进给回路如图所示，它可以实现快进工进快退的工作循环。根据此回路工作原理，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） 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. 专心-专注-专业