【机械类毕业论文中英文对照文献翻译】气压系统及各种阀门的基本介绍
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机械类毕业论文中英文对照文献翻译
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【机械类毕业论文中英文对照文献翻译】气压系统及各种阀门的基本介绍,机械类毕业论文中英文对照文献翻译,机械类,毕业论文,中英文,对照,文献,翻译,气压,系统,各种,阀门,基本,介绍
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（学号）： 07长春理工大学光电信息学院毕 业 设 计（论 文）译文姓 名刘飞学 院长春理工大学光电信息学专 业机械电子工程班 级08522指导教师吴翠红2012年4月28日Pneumatic system and various valve basic introductionPneumatic systems use pressurized gases to transmit and control power. As the name implies, pneumatic system typically use air (rather than some other gas) as the fluid medium because air is a safe ,low-cost ,and readily available fluid. It is particularly safe in environments where an electrical spark could ignite leaks from system components.In pneumatic systems, compressors are used to compress and supply the necessary quantities of air. Compressors are typically of the piston, vane or screw type. Basically a compressor increases the pressure of a gas by reducing its volume as described by the perfect gas laws. Pneumatic systems normally use a large centralized air compressor which is considered to be an infinite air source similar to an electrical system where you merely plug into an electrical outlet for electricity. In this way, pressurized air can be piped from one source to various locations throughout an entire industrial plant. The compressed air is piped to each circuit through an air filter to remove contaminants which might harm the closely fitting parts of pneumatic component such as valves and cylinders. The air then flows through a pressure regulator which reduces the pressure to the desired level for the particular circuit application. Because air is not a good lubricant (contains about 20% oxygen ), pneumatics systems required a lubricator to inject a very fine mist of oil the air discharging from the pressure regulator. This prevents wear of the closely fitting moving parts of pneumatic components.Free air from the atmosphere contains varying amounts of moisture. This moisture can be harmful in than it can wash away lubricants and thus cause excessive wear and corrosion. Hence, in come applications, air driers are needed to remove this undesirable moisture. Since pneumatic systems exhaust directly into the atmosphere, they are capable of generating excessive noise. Therefore, mufflers are mounted on exhaust ports of air valves and actuators to reduce noise and prevent operating personnel from possible injury resulting not only from exposure to noise but also from high-speed airborne particles.There are several reasons for considering the use of pneumatic systems instead of hydraulic systems. Liquids exhibit greater inertia than do gases. Therefore, in hydraulic systems the weight of oil is a potential problem when accelerating and decelerating and decelerating actuators and when suddenly opening and closing valves. Due to Newtons law of motion (force equals mass multiplied by acceleration),the force required to accelerate oil is many times greater than that required to accelerate an equal volume of air. Liquids also exhibit greater viscosity than do gases. This results in larger frictional pressure and power losses. Also, since hydraulic systems use a fluid foreign to the atmosphere, they require special reservoirs and no-leak systems use air which is exhausted directly back into the surrounding environment. Generally speaking, pneumatic systems are less expensive than less expensive than hydraulic systems.However, because of the compressibility of air, it is impossible to obtain precise controlled actuator velocities with pneumatic systems. Also, precise positioning control is not obtainable. While pneumatic pressures are quite low due to pressures can be as high as 10,000 psi. Thus, hydraulics can be high-power systems, whereas pneumatics are confined to low-power applications. Industrial applications of pneumatic systems are growing at a rapid pace.Underneath introduction is widely used in all kinds of pneumatic system valve.Valve is a widely used mechanical product in each countrys economy. You can find valves commonly used in the following fields like oil, nature gas, coal, metallurgy, mining, refinery, pipe transportation, petrochemical, chemical, pharmacy, food production, power plant, water supply / drainage, heat supply, air supply, marine, vehicle, airplane, spacecraft, military, new tech, irrigation and many other flowing systems.There are self-driven valves and operated valves. Self-driven valves( like safety valve, relief valve, steam trap, check valve ) are functioning by utilizing its mechanical design or the pressure, direction of its flow medium .Operated valves( like gate valve, globe valve, ball valve, butterfly valve ) are functioning by actuator( manual, electric, hydraulic, pneumatic etc. ) or the pressure , flow direction of its medium. Due to the differences of pressure, temperature, flow, and physical-chemical character of its medium ,there are different requirements in designing and applying the pipeline system .Therefore there are numerous types of valve. GAS VALVEFrom the air valve operating principles of view, air valve performance will directly affect the work of compressor tanks, air valve for the following requirements: resistance losses small. Air valve size and airflow resistance losses of valves always speed and the size of the spring-loaded edge. Gas higher speed, the greater the energy losses; Spring-loaded edge too large, the loss is great resistance, the size of the air valve movement design guidelines to determine the reasonableness of the law. Air valve closed timely, rapid, not leak closed to improve the efficiency of machines and extended use period. Long life, work reliable. Life is the main factor restricting air valve and spring-loaded valves quality, the general long-term continuous operation of the compressors to life 80 hours; For mobile, short-term or intermittent operation of compressors, may require slightly more.Air valve and piston-type compressors are to the important components is one of the components easily damaged. It will have a direct impact on the displacement compressors, power consumption and reliability of operation, the current compressor is fast direction, and rotational speed limit is one of the key issues in improving air valve. Piston-type compressors typically use the automatic valve that the air valve is opened and closed valves on the pressure on both sides to achieve poor, and there is no other drive.PNEUMATIC VALVEPneumatic valves regulate the temperature in the context nominal pressure and may adjust various fluids, gases and steam, pneumatic - valve closed, leakage small. Pneumatic-valve at the role of the implementing agencies could reach a gas open or gas shut purposes.Pneumatic valves regulate the pneumatic enforcement agencies and regulatory valves two. Enforcement agencies to promote the implementation of devices installed, it compressed air-driven, export thrust; Regulation valves are part of the implementation of devices to regulate direct contact with the media, regulatory medium flow. The pneumatic - valve structure with simple, reliable operation, export thrust large maintenance convenient and inexpensive, such as fire blast merits pneumatic - valve widely used for chemical, oil, metallurgical, electrical, textile and other industrial production processes autopilot and remote control.PRESSURE REGULATING VALVEpressure regulating valve is a reliance on external energy transfer medium itself was pressure changes pressure-type automatic adjustment of product, you can adjust the valve in the pressure equipment debugging process in accordance with their own processes pressure regulating valves for the guide command system set pressure after pressure regulating valves value, pressure regulating valves will be natural gas pressure regulating valves, the pressure for you to set and automatically maintain its constant, pressure regulating valves in the control room for your remote control oxygen flow downstream. Flow will be used for on-site oxygen pressure regulation and feedback to control the actual process parameters to control the distance. You can easily adjust the oxygen pressure.气压系统及各种阀门的基本介绍气压系统是用压力气体传递和控制动力，正如名称所表明的那样，气压系统通常用空气（不用其他气体）作为流体介质，因为空气是安全、成本低而又随处可得的流体，在系统部件中产生电弧有可能点燃泄漏物的场合下（使用空气作为介质）尤其安全。在气压系统中，压缩机用来压缩并供应所需的空气。压缩机一般有活塞式、叶片式和螺旋式等类型。压缩机基本上是根据理想气体法则，通过减小气体体积来增加气体压力的。气压系统通常考虑采用大的中央空气压缩机作为一个无限量的气源，这类似于电力系统中只要将插头插入插座便可获得电能。用这种方法，压力气体可以从气源输送到整个工厂的各个角落，压力气体可通过空气滤清器除去污物，这些污物可能会损坏气动组件的精密配合部件如阀和气缸等，随后输送到各个回路中，接着空气流经减压阀以减小气压值适合某一回路使用。因为空气不是好的润滑剂（包括20%的氧气），气压系统需要一个油雾器将细小的油雾注射到经过减压阀的空气中，这有助于减少气动组件精密配合运动件的磨损。由于来自大气中的空气含不同数量的水分，这些水分是有害的，它可以带走润滑剂引起过分磨损和腐蚀，因此，在一些使用场合中，要用空气干燥器来除去这些有害的水分。由于气压系统直接向大气排气，会产生过大噪声，因此可在气阀和执行组件排气口安装消声器来降低噪声，以防止操作人员因接触噪声及高速空气粒子有可能引发的伤害。用气动系统代替液压系统有以下几条理由：液体的惯性远比气体大，因此，在液压系统中，当执行组件加速减速和阀突然开启关闭时，油液的质量便是一个潜在的问题，根据牛顿运动定律（力等于质量乘以加速度），产生加速运动油液所需力要比加速同等体积空气所需的力高出许多倍。液体比气体具有更大的粘性，这会因为内摩擦而引起更大的压力和功率损失；另外，由于液压系统使用的液体要与大气隔绝，故它们需要特殊的油箱和无泄漏系统设计。气压系统使用可以直接排到周围环境中的空气，一般来说气压系统没有液体系统昂贵。然而，由于空气的可压缩性，使得气压系统执行组件不可能得到精确的速度控制和位置控制。气压系统由于压缩机局限，其系统压力相当低（低于250psi），而液压力可达10000psi之高，因此液压系统可以是大功率系统，而气动系统仅用于小功率系统。下面介绍广泛应用于气压系统的各种阀门。阀门是国民经济建设中使用极为广泛的一种机械产品。阀门在石油、天然气、煤炭、冶金、和矿石的开采、提炼加工和管道输送系统中；在石油化工、化工产品，医药和食品生产系统中；在水电 、火电和核电的电力生产系统中；在城建的给排水、供热和供气系统中；在冶金生产系统中；在船舶、车辆、飞机、航天以及各种运动机械的使用流体系统中；在国防生产以及新技术领域里；在农业排灌系统中都有大量的需
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