外文翻译--蓄压器储压器

英文及译文 翻译英文原文： Accumulators An accumulator is found in many hydraulic systems. As the name suggests, it is a storage device. The various types of accumulators are studied in this chapter. A simple accumulator is sometimes used in household water system. It may consist of a tee with a side branch pipe that is capped. The air that is trapped in the side branch pipe is compressed, and then acts like a compressed spring. As a faucet is either opened or closed quickly, a sudden change in pressure and flow occurs. The trapped air acts as cushion, or shock absorber, to prevent water hammering in the piping system. The storage batter in a car is a typical example of an electrical or chemical accumulator. Chemical energy is stored in the batter is not in use. The stored chemical energy is converted into electricity that is used to start the engine. Hydraulic Accumulators A hydraulic accumulator may be used for a variety of purposes. Some of its uses are: ( 1 ) as a shock absorber； (2) to provide oil makeup in a closed system； (3) to compensate for leakage in a system； (4) to provide a source of emergency power in event of failure of the normal power supply；(5 ) to maintain steady delivery pressure over a period of time without keeping the pump operating continuously； and (6) as a transfer barrier device to separate the oil from some other fluid in the system. Types Of Accumulators Accumulators may be divided into three general types: ( 1 ) weight-loaded, (2) spring-load, and (3) air-or gas-type accumulators. The air-or gas-type Accumulators can be subdivided further into the separator and non-separator types. Weight Loaded or Gravity Types The weight-loaded or gravity-type accumulator consists of a cylinder, a movable position, a ram or plunger, and a weight. The dead weight ( which may be placed in a container) may be concrete, iron, steel, water, or other heavy material. The position should have a precision fit inside the cylinder in order to reduce leakage. The inner cylinder wall should have a honed or ground finish in order to reduce friction and wear. As hydraulic oil is pumped into the cylinder, the piston pushes the weight to a higher level. Thus the potential or stored energy of the weight is increased. The energy stored in the weight is released in the downward motion as it is required by the demands of the system. An accumulator of this type may be custom-built for a particular installation. The weight is adjusted so that the ram rises when the fluid pressure reaches a set level. The travel of the ram can be controlled by an arrangement of a cam on the plunger and limit switches. The gravity force of the piston on the oil provides a nearly constant oil pressure level for the full stroke of the piston. By providing adequate piston area and ample length of piston stroke, a large volume of fluid can be supplied at high pressure. A single large accumulator may provide service for a number of different machines. Spring-loaded Type A spring-loaded type of accumulator is illustrated. This device consists of a cylinder, a piston, and a spring. One or more springs may be used. The springs may be arranged to provide various adjustments by means of bolts. As the oil is pumped into the accumulator, the piston or plunger compresses the spring； The energy stored in the spring is released as it is required by the demands of the system. The pressure on the oil is not constant for all the positions of the piston, because the spring force depends on the movement of the spring. Usually, this type of accumulator delivers only a small amount of oil at low pressure. Air or Gas Type Hydraulic fluid or oil is nearly incompressible. This means that a large increase in oil pressure results in only a small, or negligible, decrease in the volume of oil. On the other hand, a large increase in air or gas pressure results in a large decrease in the volume of the air or gas. Relatively speaking, hydraulic oil is less elastic or spring-like than air. Oil cannot be used effectively to store energy by compressing it, whereas air or gas can be compressed to store energy. Thus, one general type of accumulator used gas or air, rather than a mechanical spring or a weight, to provide the spring-like action. Air or gas types of accumulators can be divided into two subdivisions: (1) the non-separator type, and (2) the separator type. In the non-separator type of accumulator, the oil is in direct contact with the air or gas. In the separator types of accumulator, either a solid or a flexible barrier is placed between the oil and the gas to separate the two different types of fluids. Non-separator Type A non-separator type of air or gas accumulator consists of a fully enclosed cylinder, adequate ports, and a charging valve. A portion of oil must be trapped in the bottom of the cylinder before this type of accumulator can be placed in operator. Air, nitrogen, or an inert gas is then forced into the cylinder, and the accumulator precharged to the minimum pressure requirement of the system. A so-called free surface exists between the oil and the air or gas. As a greater quantity of oil is pumped into the accumulator, the air or gas above the oil is compressed still further. The energy is stored in the compressed gas, and it is released as required by the demands of the system. This type of accumulator should be mounted in a vertical position, because the gas must be retained in the top of the cylinder. To prevent the air or gas being exhausted into the hydraulic system, only about two-thirds of the accumulator volume can be used for the air or gas volume. Approximately one-third of the remaining accumulator volume should be reserved for the oil, to prevent the air or gas from being drawn out of the accumulator to the hydraulic system. Aeration, or mixing, of the oil or air or gas may result in diminishing the precharge of the accumulator. If the air or gas is absorbed by the oil, the accumulator requires an air or gas compressor for the precharging operation of the accumulator. Separator Type ( with piston) A separator type of accumulator with a free or floating piston acting as the barrier between the air or gas and the oil is illustrated in Figure. High-pressure air or gas is charged into the space on one side of the piston, and hydraulic oil is charged into the space on the opposite side. The tube should be machined with precision. The piston packing keeps the oil and gas separated. This type of accumulator may be installed in any position. The preferred position, however, is to place the cylinder axis vertically, with the gas connection at the top. The wearing action of the packing between the piston and the cylinder should be checked after extended use, because this may result in significant leakage. A floating piston within a cylindrical accumulator is illustrated in Figure. In the design, the double-shell construction provides a pressure-balanced inner shell that contains the position and serves as a separator between the precharged air or gas and the working hydraulic fluid. The outer shell serves as a gas container. Rapid decompression of the precharged air or gas, resulting from a rapid discharge of the working hydraulic fluid, provide a coolant for the entire corking area of the inner shell. Pressure balancing ports in the piston provide equal pressure to either side both rings； this prevent pressure lock between seals. Separator Type (with diaphragm) A diaphragm-type accumulator involves two hemispheres that are made from steel forgings. The hemispheres are locked together and a flexible, convoluted, rubber diaphragm is clamped around the periphery. An air or gas precharge is applied to one of the two hemispheres； oil, under pump pressure, is applied to the opposite hemispheres to compress the sir or gas charged. As the air or gas is compressed, the pressure rises； then the gas acts as a spring. Oil pressure and gas pressure are equal, because the separating member is flexible. Bag Type The type, or bladder, type of accumulator is a seamless steel shell that is cylindrical in shape and spherical at both ends. A gas valve is located at one end of the shell and opens into the shell. A large opening through which the bag can be inserted is located at the opposite end. The bladder is made of synthetic rubber and is pear-shaped. The fully enclosed bladder, including a molded air stem, is fastened by means of a lock nut to the upper end of the shell. On the opposite end of the shell, a plug assembly containing the oil port and a pop pet valve is mounted. The accumulator cannot be disassembled while a gas charge is inside the bag. The accumulator should be installed with the end that contains the air at the top to avoid trapping the oil when discharging. Contamination As with the other components in a hydraulic system, care should be taken to avoid contamination when installing the accumulator. The accumulator should be cleaned completely before installation in the system. Since an accumulator usually forms a dead-end in the pipeline, it may not be flushes as well as some other components during system operation. The piston-type accumulator can be studied to better understand accumulator construction. The piston may be sealed with an O-ring groove, causing wear or damage to the O-ring and allowing the gas charge to leak into the oil. An arrangement in which an O-ring seal is placed between Teflon piston rings provides a means by which the piston rings can scrape contaminants from the cylinder walls, and thus protect the O-ring seal. It is a good practice to install a filter in the air or gas charging system of the accumulator. Accumulators In Systems The accumulator is often installed in a hydraulic system to absorb shocks. The hydraulic oil from a pump is piped to a four-way valve, which directs the oil flow to a cylinder containing a piston. If the valve is closed quickly, the sudden stoppage may result in oil shock waves, or a hammering effect. A violent hammering action may damage the fittings and piping. The accumulator is capable of absorbing the shocks, thus protecting the entire system. During periods when no flow of oil is required in the hydraulic system, pump delivery can be returned, or bypassed, to the reservoir at low pressure. This arrangement serves to reduce electric power requirement, oil heating, and wear of the moving parts. The accumulator can be used as a power-saving device. A piston provides a loading force-as for a clamping operation or a rolling mill operation, in which the force moves only a short distance. After the oil pressure is built up at the piston face, the accumulator can supply the loading force for a period of time. During this period it is unnecessary to keep the pump delivering at high pressure. Therefore, an unloading valve is provide to return the pump delivery to the reservoir at low outlet pressure. During the unloading process, the pump discharge pressure is a low level, while the accumulator pressure is at a high level to provide the loading force. Thus, the accumulator is a power-saving device, and also provides for absorption of shock waves. 蓄压器储压器 在很多水压设备中都能发现有一个蓄压器。正如它的名字所暗示的，它是一个存储设备。在这一章中要学习各种不同种类的蓄压器。 有时候在家庭存水设备中就会用到一个简单的蓄压器。它可以被认为是一个球坐和一个被覆盖住头的分支管组成。空气就在那个被盖住的分支管里，然后按压。随着盖帽的迅速打开盖上，气压突然改变，然后就产生了气流。里面的空气就充当了气垫或者是减弱冲击的缓冲器，用来防止管子里的水溢出。 汽车里的存储设备是一种电的或化学成分的蓄压器。不使用的化学能储存在储存器里面。储存的化学 能被转化成电能后供发动引擎使用。 水压蓄压器可能被用作不同的目的。它们的一些用途有：（ 1）作为一个减弱冲击的缓冲器；（ 2）在一个关闭的系统里提供汽油；（ 3）补充系统内的渗漏物；（ 4）在不能达到正常的引力情况下，提供紧急能量的来源；（ 5）当泵不能继续运转的时候，在一段时期内维持传送过来压力的稳定；（ 6）作为一个传输障碍物，在系统中将汽油和其他液体分离。 蓄压器的种类 蓄压器一般分为三种类型：（ 1）重量装载类型，（ 2）弹簧支撑类型，（ 3）空气或气体类型。空气或气体类型的蓄压器又可以进一步 划分为分离的和非分离的。 重量装载或重力类型 重量装载或重力类型的蓄压器是由一个圆柱体，一个可移动位置的撞击物或活塞和一个重物组成。那个无生命的重物（可能被放在容器中）可能是具体的铁，钢，水，或其他重质材料的东西。在圆柱体里的那个位置要固定准备，用来减少渗漏物。圆柱体的内壁上应该有一个磨砂的或毛的物质来减少摩擦和磨损。当水力油抽入圆筒，活塞推挤重量对高水平。 因而增加重量的潜力或储能。当它由系统的要求，需要在重量存放的能量在向下运动被释放。这个类型蓄压器也许是定制的为特殊设施。因为重量装载是被校正过 的，所以当液体压力到达设定的值的时候，活塞就会上升。撞击物的移动可能受放在活塞和计时器上的凸轮的控制。活塞的重力在油的为活塞的充分的冲程提供一个几乎恒定的油压水平。 通过提供充分活塞区域和活塞冲程的宽裕的长度，大容量流体可以被供应在高压。 一台唯一大蓄压器也许为一定数量不同的机器提供服务。 弹簧支撑类型 蓄压器的一种弹簧支撑类型被说明。这种类型是由圆柱、活塞、弹簧组成的。或许一根或更多根弹簧要被用到。这种类型的蓄压器也许通过螺栓提供各种各样的调整。当油抽入蓄压器，活塞或柱塞挤压弹簧；当系统需要时， 储存在弹簧内的能量就被释放。因为弹簧的力量取决于弹簧的运动，在油的压力为活塞的所有位置不是恒定的。 通常，这种类型的蓄压器交付仅少量油以低压。 空气或气体类型 液压机液体或油是几乎不可压缩的。 这意味着油压的大增量，导致只有一点点，或几乎不能地降低油的容量。换句话说，空气或气体压力的大增量，能导致空气或气体体积的大幅度下降。相对来说，水力油比空气较不有弹性或象弹簧的。油不可能通过压缩它有效地用于存放能量，而空气或气体可以被压缩存放能量。 因此，蓄压器的一种一般类型使用气体或空气，而不是机械的弹簧或重 量装置，提供像弹簧的作用。 蓄压器的空气或气体类型可以被划分成二细分： (1)非分离器类型和 (2)分离器类型。在蓄压器的非分离器类型中，石油是直接与空气或气体联系。 在蓄压器的分离器类型中，一个坚实或一个灵活的障碍被安置在石油和气体之间分离流体的二种不同类型。 非分离类型 空气或气体的非分离蓄压器类型由一个充分的附上的圆筒、充分口岸和一个充气阀组成。在此种蓄压器能被操作员使用之前，一部分油必须在圆筒的底部被困住。空气、氮气或者惰性气体然后被强迫入圆筒，蓄压器预加压力满足系统需要的最小压力。所谓的自 由表面存在石油和空气或者气体之间。 当一个质量更好的油被压入蓄压器中，在油之上的空气或气体被进一步压缩。能量存储在压缩气体中，当系统需要是被释放。 这种类型的蓄压器应该安装在一个垂直的位置上，因为气体必须保留在圆筒的上面。为了防止被用尽的空气或气体进入水压系统中，只有三分之二的圆筒的容量才能被空气或气体使用。剩余的三分之一的圆筒的容量是为油后备的，为了防止空气或气体从蓄压器发挥出来进到系统中去。通风或者混合的油或空气或气体可能导致减少蓄压器的预压力。如果空气或气体被油吸收了，蓄压器就需要一个空气的或 气体的压气机来对蓄压器进行预加压。 分离类型（带活塞的） 带有自由浮动活塞的分离类型的蓄压器，在空气或气体和油之间是一个障碍，这在图中有被说明。高压空气或气体被加压在活塞一边的空间中，并且水力油被加压在反面的空间中。 应该用机器制造管与精确度。 活塞包装使油和气体相分离。 此种蓄压器在所有位置也许被安装。然而， 首选的位置，是垂直安置圆筒轴，与在上面的气体连接。因为这也许导致重大漏出，应该在延长用途以后检查在活塞和圆筒之间的包装的佩带的活动。 在一台圆筒柱型蓄压器内，一个浮动的活 塞被用图说明了。在设计中，双壳构造的蓄压器保持内壳层压力的平衡。内壳层包含了分离预加压的空气或气体和工作液压机液体的位置和服务。外壳则作为气体容器。 被预先加压的空气或气体的迅速解压，起因于工作液压机液体的迅速放电，为内壳层的整个塞住的区域提供蓄冷剂。 在活塞的压力平衡口岸提供相等的压力给任一边两个圆环 ； 这防止在封印之间的压力锁。 分离类型（带膜片的） 膜片类型的蓄压器包含两个由钢锻造的半球。两个半球锁在一起，然后一张灵活，复杂，橡胶膜片在周围附近被夹紧。 空气或气体预加压后被放到其中的一个半球里 ；油，在泵浦压力下，被放于相反半球来压缩 填充的空气或气体。当空气或气体被压缩，压力就变大；然后空气就相当于是弹簧。因为分离的成员是灵活的，油压和气体压力是相等的。 包类型 这种类型的蓄压器是一根无缝的钢毛管。而这个包或者囊是一个圆柱体在有形的球状的两个末端。排气阀位于壳的一个末端并且打开入壳。一个可以通过包插入的开口在相反的末端。囊由合成橡胶制成并且是梨状的。包含一个模塑的空气的阀杆紧附在囊上。它通过螺帽被紧固在壳的上端。在壳的相反方，安装有一个包含供油港和流行石油阀门装置的塞子。当气体加压是在 袋子里面时，蓄压器不可能被拆卸。这种蓄压器应当安装在顶端有空气的部分，以免当释放时油被困住。 污染 当安装蓄压器时，在液压机系统中装有其他零组件时，应当注意避免污染。蓄压器被安装到系统之前应当彻底的清洗。因为在管道内，蓄压器通常是一种固定的形式，因此，在系统运作是，它可能不能像其他零部件那样冲洗。学习活塞式的蓄压器能更好的理解蓄压器的构造。活塞也许密封成 O 环凹线，造成对 O 环的磨损或伤害而且使得空气加压流入油中。O 环封印安置在聚四氟乙烯活塞环之间，提供活塞环可能刮从圆筒墙壁的污染物的方法和因而保护 O 环 封印。 在空气或气体的蓄压器系统中安装过滤器是一种很好的练习。 蓄压器在系统中 蓄压器经常被安装在一种液压系统中来缓冲震动。从泵浦的水力油被用管道输送到一个四种方式的阀门，指挥着油流到包含活塞的圆筒。 如果阀门迅速被关闭，突然的停止也许导致石油危机波浪或者一个锤击的作用。 一次猛烈锤击的行动也许损坏配件和管道系统。 蓄压器能够承受震动，因而可以保护整个系统。当液压系统没有需要油流动的这段期间内，泵排量可以以低压返回或者被绕过，到水库。 这个措施能减少对电力和运动机件的油热和磨损。 蓄压器可以使用作为力量挽救设备。 活塞为夹紧的操作或轧板机操作提供装货力量，力量移动仅一个短的距离。 在油压被加强在活塞面孔之后，蓄压器可能在一段时间提供装货力量。 在这个期间内泵浦持续交付在高压是不必要的。因此，一个卸荷阀是提供以低出口压力退回泵排量到水库的。 在卸载的过程期间，泵浦释放的压力在一个低水平上，而蓄压器的压力在一个高水平上，来提供装货力量。因此，蓄压器是一个力量挽救设备，并且提供冲击波的吸收。 第八课 数字信号处理器（ DSPs） 在很多情况下，模拟信号要被不同的方式处理， 像过滤和光谱分析。由于对性能的要求，灵活性的需要和需要减少发展或测试的时间，设计模式硬件执行这些作用是可能的，但是变得越来越不实用了。换句话说，设计执行对信号的先进的分析的模式是难得。抽样一个模拟信号到数字式领域里的行为，和申请处理在使用计算的算法的数字式版本并且在处理后可能恢复信号到模式领域的过程叫做数字信号处理。处理器涌现了在为嵌入信号处理操作被专门研究的过去 15 年期间内，并且这种处理器称 DSP，代表数字信号处理器。 如今，有许多来自不同产方设计的数字信号处理器，每一种都是为特定价钱 /性能 /使用群体设 计的。像德州仪器和摩托罗拉这些大型产商，即为特定领域提供特定的数字信号处理器，像电动机控制或调制解调器，而且还提供一般的高性能的数字信号处理器，这中处理器能处理广域范围内的处理任务。升级工具和软件也是可用的，而且有商家为数字信号处理做升级软件，这种处理器能够允许程序员用简的 drag n drop统计分析法来处理复杂的程序算法。 根据下面的定点和浮点的体系结构，数字信号处理器或多或少被归入两个类别。定点设备通常起作用于 16 位的字，而浮点设备起作用于 3240 位的浮点字。不用说，定点设备通常更加便 宜。 另一个重要的体系结构的区别就是，当只有一台“通用”记数器，使他们相当棘手而且更加重要的处理时，定点处理器只倾向于有累加器的体系结构。 这使得 C 编译器本质上地效率低。浮点数字信号处理器更像带有寄存器组的普通的通用 CPUs。在市场上，有成千上万种不同的数字信号处理器，而且很难为某个项目找到一个适合的数字信号处理器。最好的办法大概就是设定一个限制条件，然后和大的产商生产的处理器进行比较。数字信号处理器的四大产商是：德州仪器，摩托罗拉， AT&T 和模拟设备。 数模变换 在 MPEG 音频解码情况下， 数字式压缩的数据被投向执行解码的 DSP，然后被解码的样品必须转换回到模式领域和发生的信号被投向放大器或相似的音响器材里。 这种数模变换（ DAC）别具有相同名字的电路执行。不同的数字信号处理提供不同的操作和质量，如测量由位的 THD (总谐波畸变 )，数字，线性、速度、过滤器特征和其他东西。 德州仪器的 TM320 家庭数字信号处理器 TM320 家庭型的包括定点，浮点，多重处理机数字信号处理器 (DSPs)和定点 DSP 控制器。 TM320 的数字信号处理器有一个特别为实时信号处理明确地设计的体系结构。 DSP 控制器的 C24x 系列与控制器外围设备