液压系统的外文文献翻

1、jingchu university of technology毕业设计（论文）外文文献翻译译文题目 hydraulic system 专 业机械设计制造及其自动化 班 级 09机制一班 姓 名 汪康 学 号 2009403010107 指导教师 王霞 机械工程学院hydraulic systemthere are only three basic methods of transmitting power：electrical，mechanicaland fluid powermost applications actually use a combination of the three

2、methods to obtain the most efficient overall systemto properly determine which principle method to use。it is important to know the salient features of each typefor example，fluid systems call transmit power more economically over greater distances than can mechanical typeshowever。fluid systems are re

3、stricted to shorter distances than are electrical systems hydraulic transmission there are many outstanding advantages, it is widely used, such as general industrial use of plastics processing machinery, the pressure of machinery, machine tools, etc.; operating machinery engineering machinery, const

4、ruction machinery, agricultural machinery, automobiles, etc.; iron and steel industry metallurgical machinery, lifting equipment, such as roller adjustment device; civil water projects with flood control and dam gate devices, bed lifts installations, bridges and other manipulation of institutions; s

5、peed turbine power plant installations, nuclear power plants, etc.; ship from the deck heavy machinery (winch), the bow doors, bulkhead valve, stern thruster, etc.; special antenna technology giant with control devices, measurement buoys, movements such as rotating stage; military-industrial control

6、 devices used in artillery, ship anti- rolling devices, aircraft simulation, aircraft retractable landing gear and rudder control devices and other devices.the role of the hydraulic system to increase the force by changing the pressure. a hydraulic system is good or bad depends on the system design

7、is reasonable, the merits of the performance system components, system, pollution prevention and treatment, while the last point is particularly important. in recent years, chinas domestic hydraulic technology has greatly improved, not simply using hydraulic technology from abroad for processing. a

8、complete hydraulic system consists of five parts, namely, power components, the implementation of components, control components, auxiliary components (annex) and the hydraulic oil. the role of dynamic components is the original motivation of the mechanical energy into fluid pressure energy, the hyd

9、raulic system of pumps, which provide power to the entire hydraulic system. structures of hydraulic pumps generally have gear pumps, vane pumps and piston pumps.implementation of components (such as hydraulic cylinders and hydraulic motors) is to pressure the liquid can be converted to mechanical en

10、ergy to drive the load for a linear reciprocating movement or rotational movement.control components in the hydraulic system control and regulation of fluid pressure, flow and direction. according to the different control functions, hydraulic valves can be divided into pressure control valves, flow

11、control valves and directional control valve. pressure control valve is divided into benefits flow valve (safety valve), pressure relief valve, sequence valve, pressure switch, etc.; flow control valves including throttle, adjusting valves, flow diversion valve assembly; directional control valve in

12、cludes a check valve, check valve, shuttle valve, valve and so on. under the control of different ways, hydraulic valves can be divided into switching control valves, control valves and the fixed value proportional control valve. auxiliary components, including fuel tanks, filters, tubing and pipe j

13、oints, seals, quick couplings, high pressure ball valve, hose assembly, pressure fittings, pressure gauge, oil level, oil temperature meter and so on. hydraulic system of hydraulic oil is the work of the energy transfer medium, a variety of mineral oil, emulsion, oil hydraulic molding hop categories

14、the role of the hydraulic system is to help humanity work. mainly by the implementation of components to rotate or pressure into a reciprocating motion. hydraulic principle ：it consists of two cylinders of different sizes and composition of fluid in the fluid full of water or oil. water is called hy

15、draulic press; the said oil filled hydraulic machine. each of the two liquid a sliding piston, if the increase in the small piston on the pressure of a certain value, according to pascals law, small piston to the pressure of the pressure through the liquid passed to the large piston, piston top will

16、 go a long way to go. based cross-sectional area of the small piston is s1, plus a small piston in the downward pressure on the f1. thus, a small piston on the liquid pressure to p = f1/si, can be the same size in all directions to the transmission of liquid. by the large piston is also equivalent t

17、o the inevitable pressure p. if the large piston is the cross-sectional area s2, the pressure p on the piston in the upward pressure generated f2 = pxs2 cross-sectional area is a small multiple of the piston cross-sectional area. from the type known to add in a small piston of a smaller force, the p

18、iston will be in great force, for which the hydraulic machine used to suppress plywood, oil, extract heavy objects, such as forging steel.the secret of hydraulic systems success and widespread use is its versatility and manageabilityfluid power is not hindered by the geometry operations when the pot

19、ential difference between the tool and the work piece is sufficiently high, a transient spark discharges through the fluid, removing a very small amount of metal from the work piece of the machine as is the ease in mechanical systemsalso，power can be transmitted in almost limitless quantities becaus

20、e fluid systems are not so limited by the physical 1imitations of materials as are the electrical systemsfor example，the performance of an electromagnet is limited by the saturation limit of steelon the other hand，the power limit of fluid systems is 1imited only by the strength capacity of the mater

21、ialindustry is going to depend more and more on automation in order to increase productivitythis includes remote and direct control of production operations，manufacturing processes。and materials handlingfluid power is the muscle of automation because of advantages in the following four major categor

22、ies1 the precise convenient control by operating a simple joystick and buttons, the operators of the hydraulic system and can immediately start, stop, and deceleration and can provide any power, position precision for one over ten thousand inch position control. a make the pilot rises and fall the l

23、anding gear on the hydraulic system, when the pilot to a certain direction control valves, pressure oil into hydraulic cylinder of a cavity and came down on the landing gear. the pilot to move in the opposite direction control valves, allow the oil into the hydraulic cylinder of another chamber to t

24、ake back on the landing gear. 2 multiplication of force a fluid power system(without using cumbersome gears，pulleys，and levers)can multiply forces simply and efficiently from a fraction of an ounce to several hundred tons of output3 constant force or torqueonly fluid power systems are capable of pro

25、viding constant force or torque regardless of speed changesthis is accomplished whether the work output moves a few inches per hour，several hundred inches per minute，a few revolutions per houror thousands of revolutions per minute4 simplicity，safety，economygeneral，fluid power systems use fewer movin

26、g parts than comparable mechanical or electrical systemsthus，they ale simpler to maintain and operatethis，in turn，maximizes safety，compactness，and reliabilityfor example，a new power steering control designed has made all other kinds of power systems obsolete on many offhighway vehiclesthe steering u

27、nit consists of a manually operated directional control valve and meter in a single bodytransportation，marine technology，and offshore gas and petroleum explorationin addition，very little input torque is required to produce the control needed for the toughest applicationsthis is important where 1imit

28、ations of control space require a small steering wheel and it becomes necessary to reduce operator fatigueadditional benefits of fluid power systems include instantly reversible motion。automaticprotection against overloads，and infinitely variable speed controlfluid power systems also have the highes

29、t horsepower per weight ratio of any known power sourcethe three hydraulic system diseases.1 as result of heat transmission medium (hydraulic oil) in the flow velocity in various parts of the existence of different, resulting in the existence of a liquid within the internal friction of liquids and p

30、ipelines at the same time there is friction between the inner wall, which are a result of hydraulic the reasons for the oil temperature. temperature will lead to increased internal and external leakage, reducing its mechanical efficiency. at the same time as a result of high temperature, hydraulic o

31、il expansion will occur, resulting in increased compression, so that action can not be very good control of transmission. solution: heat is the inherent characteristics of the hydraulic system, not only to minimize eradication. use good quality hydraulic oil, hydraulic piping arrangement should be a

32、voided as far as possible the emergence of bend, the use of high-quality pipe and fittings, hydraulic valves, etc.2 the vibration of the vibration of the hydraulic system is also one of its malaise. as a result of hydraulic oil in the pipeline flow of high-speed impact and the control valve to open

33、the closure of the impact of the process are the reasons for the vibration system. strong vibration control action will cause the system to error, the system will also be some of the more sophisticated equipment error, resulting in system failures. solutions: hydraulic pipe should be fixed to avoid

34、sharp bends. to avoid frequent changes in flow direction, can not avoid damping measures should be doing a good job. the entire hydraulic system should have good damping measures, while avoiding the external local oscillator on the system.3 the leakage of the hydraulic system leak into inside and ou

35、tside the leakage. leakage refers to the process with the leak occurred in the system, such as hydraulic piston-cylinder on both sides of the leakage, the control valve spool and valve body, such as between the leakage. although no internal leakage of hydraulic fluid loss, but due to leakage, the co

36、ntrol of the established movements may be affected until the cause system failures. outside means the occurrence of leakage in the system and the leakage between the external environments. direct leakage of hydraulic oil into the environment, in addition to the system will affect the working environ

37、ment, not enough pressure will cause the system to trigger a fault. leakage into the environment of the hydraulic oil was also the danger of fire. solution: the use of better quality seals to improve the machining accuracy of equipment.in the hydraulic system and its system，the sealing device to pre

38、vent leakage of the work of media within and outside the dust and the intrusion of foreign bodies. seals played the role of components, namely seals. medium will result in leakage of waste, pollution and environmental machinery and even give rise to malfunctioning machinery and equipment for persona

39、l accident. leakage within the hydraulic system will cause a sharp drop in volumetric efficiency, amounting to less than the required pressure, can not even work. micro-invasive system of dust particles can cause or exacerbate friction hydraulic component wear, and further lead to leakage.therefore,

40、 seals and sealing device is an important hydraulic equipment component. the reliability of its work and life is a measure of the hydraulic system an important indicator of good or bad. in addition to the closed space, are the use of seals, so that two adjacent coupling surface of the gap between th

41、e need to control the liquid can be sealed following the smallest gap. in the contact seal, pressed into self-seal-style and self-styled self-tight seal (is, sealed lips) two. 液压系统一般仅有以下三种基本方法传递动力：电气、机械和液压。大多数应用系统实际上是将三种方法组合起来而得到最有效的最全面的系统。为了合理地确定采取哪种方法，重要的是了解各种方法的显著特征。例如液压系统在长距离上比机械系统更能经济地传递动力。然而液压

42、系统与电气系相比，传递动力的距离较短。液压传动有许多突出的优点，它被广泛的应用，如一般工业用的塑料加工机械，压力机械，机床等；应用机械设备工程机械，建筑机械，农业机械，汽车等；钢铁行业的冶金机械，起重机械，还有轧辊调整装置等；水利工程中的控制闸门装置，河床升降装置，桥梁和其他操作机构；发电厂高速涡轮装置，核电站等；船舶甲板用的起重机械（绞车），船头门，舱壁阀、船尾推进器等；特殊技术用的巨型天线控制装置、测量浮标、升降旋转舞台等；军事工业用的火炮操纵装置、船舶减摇装置、飞行器仿真、飞机起落架的收放装置和方向舵控制装置等。特殊技术的天线控制装置，测量浮标，升降旋转舞台；军用的火炮操纵装置，船舶减摇

43、装置，飞行器仿真，飞机起落架收放装置和方向舵控制装置和其他设备。液压系统的作用为通过改变压强增大作用力。一个液压系统的好坏取决于系统设计的合理性、系统元件性能的优劣，系统的污染防护和处理，而最后一点尤为重要。近年来我国国内液压技术有很大的提高，不再单纯地使用国外的液压技术进行加工。一个完整的液压系统由五个部分组成，即动力元件、执行元件、控制元件、辅助元件（附件）和液压油。动力元件的作用是将原动机的机械能转换成液体的压力能，指液压系统中的油泵，它向整个液压系统提供动力。液压泵的结构形式一般有齿轮泵、叶片泵和柱塞泵。执行元件(如液压缸和液压马达)的作用是将液体的压力能转换为机械能，驱动负载作直线往

44、复运动或回转运动。控制元件(即各种液压阀)在液压系统中控制和调节液体的压力、流量和方向。根据控制功能的不同，液压阀可分为压力控制阀、流量控制阀和方向控制阀。压力控制阀又分为益流阀(安全阀)、减压阀、顺序阀、压力继电器等；流量控制阀包括节流阀、调整阀、分流集流阀等；方向控制阀包括单向阀、液控单向阀、梭阀、换向阀等。根据控制方式不同，液压阀可分为开关式控制阀、定值控制阀和比例控制阀。辅助元件包括油箱、滤油器、油管及管接头、密封圈、快换接头、高压球阀、胶管总成、测压接头、压力表、油位油温计等。液压油是液压系统中传递能量的工作介质，有各种矿物油、乳化液和合成型液压油等几大类。液压系统的作用是帮助人类工

45、作，主要通过执行元件将压力转换为旋转或往复运动。液压原理：它由两个不同大小的缸体充满了水或油。充满水的称为“水压机”，充满油的称为“液压机”。两个液缸每个都有一个可动的活塞，如果在小活塞上加点压力，根据帕斯卡定律，小活塞的压力通过液体的压力传递到大活塞，顶端的活塞将前进很长的距离。基本小活塞的横截面积为s1，外加一个小活塞上一个向下的力f1。因此，小活塞对液体的压强p=f1/s1的，可以在所有方向上传输同样大小。通过大活塞的压力也为p。如果大活塞的横截面积为s2，活塞的压强p向上的压力f2=p*s2，横截面积是小活塞的几倍，加给小活塞小的力，活塞会有大的压力，由此用液压机压制胶合板，油，提起重物，锻造炼钢。液压系统成功而又广泛使用的秘密在于它的通用性和易操作性。液压动力传递不会像机械系统那样受到机器几何形体的制约，另外，液压系统不会像电气系统那样受到材料物理性能的制约，它对传递功率几乎没有量的限制。例如，一个电磁体的性能受到钢的磁饱和极限的限制，相反，液压系统的功率仅仅受材料强度的限制。企业为了提高生产率将越来越依靠自动化，这包括远程和直接控制生产操作加工过程和材料处理等。液压动力之所以成为自动化的重要