外文翻譯--液壓系統(tǒng)的動力源-泵和蓄能器

附 錄 外文文獻原文： The commonly used sources of power in hydraulic systems are pumps and accumulators . Similarly,accumulator connected to atmosphere will dischange oil at atmosphere pressure until it empty. only when connected to a system having resistance to flow can pressure be developed. Three types of pumps find use in fluid-power systems:rotary,reciprocating or piston-type, and 3,centrifugal pumps. Simple hydraulic system may use but one type of pump . The trend is to use pumps with the most satisfactory characteristics for the specific tasks involved . In matching the characteristics of the pump to the requirements of the hydraulic system , it is not unusual to find two types of pumps in series . For example , a centrifugal pump may be to supercharge a reciprocating pump , or a rotary pump may be used to supply pressurized oil for the contronls associated with a reversing variabledisplacement pumps . Most power systems require positive displacement pumps . At high pressure , reciprocating pumps are often preferred to rotary pumps . 1、 Rotary pumps These are built in many differnt designs and extremely popular in modern fluid power system . The most common rotay-pump designs used today are spurgear , internal gear ,generated rotor , sliding vane ,and screew pumps . Ehch type has advantages that make it most suitable for a given application . 2、 Gear pumps Gear pumps are the simplest type of fixed displacement hydraulic pump available . This type consists of two external gear , generally spur gear , within a closed-fitting housing . One of the gear is driven directly by the pump drive shaft . It ,in turn , then drives the second gear . Some designs utilize helical gears ,but the spur gear design predominates . Gear pumps operate on a very simple principle . As the gear teeth unmesh , the volume at the inlet port A expands , a partial vacuum on the suction side of the pump will be formed . Fluid from an external reservoir or tank is forced by atmospheric pressure into the pump inlet . The continuous action of the fluid being carried from the inlet to the discharge side one of the pump forces the fluid into the system . 3、 Vane pumps The vane pump consists of a housing that is eccentric or offset with respect to the drive shaft axis . In some models this inside surface consists of a cam ring that can be rotated to shift the relationship between rotor are rectangular and extend radially from a center radius to the outside diameter of the rotor and from end to end . A rectangular vane that is essentially the same size as the slot is inserted in the slot and is free to slide in and out . As the rotor turns , the vanes thrust outward , and the vane tips track the inner surface of the housing , riding on a thin film of fluid . Two port or end plates that engage the end face of the ring provide axial retention . Centrifugal force generally contributes to outward thrust of the vane . As they ride along the eccentric housing surface , the vane move in and out of the rotor slots . The vane divide the area between the rotor and casing into a series of chambers .The sides of each chamber are formed by two adjacent vanes ,the port or end plates , the pump casing and the rotor . These chambers change in change in volume depending on their respective position about the shaft . As each chamber approaches the inlet port , its vanes move outward and its volume expands , causing fluid to flow into the expanded chamber . Fluid is then carried within the chamber around to the dischange port . As the chamber approaches the discharge port , its vanes are pushed inward ,the volume is reduced , and the fluid is forced out the discharge port . Vane pump speed is limited by vane peripheral speed . High peripheral speed will cause cavitation in suction cavity . which results in pump damage and reduced flow . An imbalance of the vanes can cause the oil film between the vane tips and the cam ring to break down , resulting in metal-to-metal contact and subsequent increased wear and slipage . One metheod applied to eliminate high vane thrust loading is a dual-vane construction . 4、 Piston-type pump All piston pumps operate by allowing oil to flow into a pumping cavity as a piston retreats and then forcing the oil out into another chamber as the piston advances . Design differences among pumps lie primarily in the methods of separating inlet from outlet oil . 5、 In-line piston pump The siplest typeof axial piston pump is the swash plate in-line design .The cylinder are connected though piston shoes and a retracting ring , so that the shoes beat anainst an angled swash plate . As the block turns ,the piston shoes follow the swash plate ,causing the piston to reciprocate . The ports are arranged in the valve plate so that the pistons pass the inlet port as they are being pulled out and pass the outlet port as they are being forcing back in . The angle of the swash plate controls the delibery . Where the swash plate is fixed , the pump is of the constant-displacement type . In the variable-displacement , inline piston pump , the swash plate is moumted on a pivoted yoke . As the swash plate angle is increased , the cylinder stroke is increase , resulting in a greater flow . A pressure compensator control can position the yoke automatically to maintain a constant output pressure . 6、 BENT-axis piston pump As the shaft roates , distance between any one piston and the valving surface changes continually . Each piston moves away from the valving surface during one half of the revolution and toward the valving surface during the other half . The inlet chamber is in line as the pistons move away , and the outletr chamber is in line as the pistons move closer , thus drawing liquiring in during one half of the inlet chamber as the pistons are moving away from the pintle . Thereforce , during rotation , pistons draw liquid into the cylinder bores as they pass the inlet side of the pinntle and force that liquid out of the bores as they pass the outlet side of the pintle . The displacement of this pump varies with the offset angle , the maximum angle being 30 degree ,the minimum zero . Fixed displacement models are usually avaiable with 23 degree angle .In the variable displacement construction a yoke with an external control is used to change the angle . With some contronls , the yoke can be moved over center to reverse the direction of flow from the pump . 7、 Pump/system interaction Pressure-compensated variavle delivery pumps do not require a relief valve in the high pressure line . The pressure compensation feature eliminates the need for the relief valve . In nearly all working systems ,however , at least one is used on just-in-case basis . The use of a pressure compensator , while avoiding dependence on a relief valve , brings on its own problems . The actuator -spring-spool arrangement in the compensator is a dynamic , damped-mass-spring arrangement . However , when the system calls for a chang in axhieve their maxmum volume as they reach the inlet port , the maximum volume of fluid will ve moved . If the relationship between housing and rotor is changed such that the chambers achieve their minimum of zero volume as they reach the inlet port , the pump delivery will be reduced to zero . Vane pump speed is limited by vane peripheral speed . High peripheral speed will cause cavitation in suction cavity , which results in pump damage and reduced flow . An imbalance of the vanes can cause the oil film between the cane tips and the cam ring to break down , resulting in metal-to-metal contact and subsequent increased wear and slipage . One method applied to eliminate high vane thrust loading is a dual-vane construction . In the dual-vane construction , tow independent vanes are located in each totor slot chmbered edges along the sides and top of each vane from a channel that essentially balances the hydraulic pressure on the top and bottom of each pair of vanes . Centrifugal force cause the vane to follow the contour of the cam-shaped ring .There is just sufficient seal between the vanes and ring without destroying the thin oil film . 外文文獻中文翻譯： 常用的 液壓系統(tǒng)的 動力源 是 泵和蓄 能器 。 一般情況下， 一個 蓄能器在正常的大氣壓力下，連續(xù)的 向 各系統(tǒng)中壓入液壓油 ， 直至 將所儲存的能量全部用完為止。 只有當 其 連接 的 系統(tǒng) 中， 具有抗流壓力 時 才能 夠 得到 補充。 在液壓系統(tǒng)和液力系統(tǒng)中，常使用液壓泵有回轉(zhuǎn)式、 往復式 、 活塞式 或者 離心 式三種類型： 簡單液壓系統(tǒng) 一般使用的都是第一 類 液壓 泵 。 目前的 發(fā)展 趨勢是 針對具體的工作任務和工況，選用最佳的液壓泵類型。在符合特性和要求的液壓泵中，找到兩種不同類型的液壓泵式很常見的。 例如 ， 離心泵 ，往復泵都可以 可對 系統(tǒng)增壓 ， 旋轉(zhuǎn)泵 和變量液壓泵聯(lián)合使用也可以提供高壓的液壓油。 大 部分 動力 系統(tǒng)還需要采取 容積式液壓泵 泵 。而在較高的體統(tǒng)壓力下， 往復泵往往 要優(yōu) 于回轉(zhuǎn)泵 。 1、回轉(zhuǎn)泵 這些 形式的液壓泵因為具有 許多不同的設計 形式 而極受歡迎 ， 在現(xiàn)代流體動力系統(tǒng)。 最常見的旋轉(zhuǎn)泵的設計 形式，包括內(nèi)部使 用齒輪 的、 內(nèi)部 使用 轉(zhuǎn)子 的、內(nèi)部采用滑動葉片的和使用 螺桿 的。 其中， 每一種類型都有 其獨特的優(yōu)點，都有其最適合的一定的應用場合。 2、齒輪泵 齒輪泵是 可以提供的 最簡單的一種液壓泵 。 這 一 類型 的液壓泵一般包括 兩個外 嚙合的 齒輪 ， 一般 是 圓柱 直 齒輪 ，安裝 在一個 密封的殼體里面。 其中 一個齒輪 由液壓泵的傳動軸直接驅(qū) 動， 第一個齒輪 然后再推動第二輪 。還 有 一 些設計 中 利用螺旋齒輪 ， 但是 一般以 齒輪設計為主 。 齒輪泵的 動作的原理 非常簡單 ，如 插圖 7.3 所示。 由于 在齒輪的輪齒在脫開嚙合時， 進氣道擴大 ， 液壓泵將會形成 局部真空 的具有吸力的空腔。 流體 在系統(tǒng)的壓力下被 從外部 油箱 或罐體中壓入， 連續(xù) 運動 的 液壓油在液壓泵的作用下，從真空的吸力空腔中被送入排出液壓油的一側(cè) B 側(cè)。 3、葉片泵 葉片泵 一般是由一個相通 的 腔體， 是偏心或抵消對傳動軸軸線 。 在 一些 模型內(nèi) 的 表面設有一個凸輪環(huán) ，一個 可旋轉(zhuǎn) 移動的長方形的轉(zhuǎn)子，轉(zhuǎn)子的 徑向延長 ，從一個中 心 ， 半徑為外徑的轉(zhuǎn)子 ，到末端 結(jié)束 。 上 面 是 尺寸 大小相同的插槽 ，矩形葉片 一般 插入到插槽中 ， 并且 可以自如的滑入和滑出。 當 轉(zhuǎn)子 轉(zhuǎn)動時， 葉片 被 向外 甩出， 而葉片 尖端則貼緊其運動 軌道 空腔的 內(nèi)表面 ， 處于液壓油的薄膜的上面。 兩個 油口 或 端 板 ，向 環(huán)形 的 端面提供軸向 的存儲。 通常 離心 有助于葉片的 向外推 出。當葉片處于 偏心 空腔的 表面上 時， 葉片 從轉(zhuǎn)子的縫隙中甩出和甩。 葉片 將套管和 轉(zhuǎn)子 之間的區(qū)域分成 一系列的 小空腔。每一個小空腔都是由 兩個相鄰葉 片，油口或者端盤，液壓 泵殼 體 和轉(zhuǎn)子 形成。 這些 空腔的容積的 變化取決于 他們相對于軸的相 對位置。 當 每個廳內(nèi)靠近進 內(nèi)氣孔的時候， 其葉片向外移動，其 空腔的容積 膨脹， 造成 液壓油 流入擴大 空腔。 流體 隨后被帶入圍繞著排油孔的空腔內(nèi)。當這些空腔靠近排油孔時，葉片被甩入腔內(nèi)，空腔的容積減小，液壓油隨即被壓出排油孔。 葉片泵的速度 一般要受到 葉片圓周速度 的限制 。 過 高 的 圓周速度將導致空腔內(nèi) 出現(xiàn) 負壓 ，從而 導致 液壓 泵損壞和 流量減小 。 一個 不平衡 的葉片 將會引起葉片頂端和 凸輪環(huán) 之間的 油膜 的破壞 ， 從而進一步 導致金屬 和 金屬 之間的直接 接觸，因而增加了磨損和 葉片泵的動力傳動損耗 。消除這種葉片泵的葉片的高推力負荷的方法之 一就是采用雙葉片結(jié)構(gòu)。 4、活塞式泵 所有 的 活塞式 液壓泵的運行原理 ， 都是通過液壓油 流入泵腔 而推動 活塞 向后面移動 ，然后 活塞再向前移動，從而將液壓油排出，使得液壓油進入泵的另一個腔室中 。 不同的泵的 設計差異泵主要在于 活塞進入和推出從而將液壓油 分離 的方法 。 5、直軸式柱塞泵 最簡單的 軸向柱塞泵是 將 沖板 進行線性化 設計 。 氣缸 與活塞的回縮盤之間 相連 ， 使 移動的回縮盤成 傾斜式。 當傾斜圓盤轉(zhuǎn)動的時候 ， 柱 塞 的端腳 斜盤 上運動 ， 從而使得 活塞 桿不斷的往復的運動，同時因為油 口分別安排在閥板 上 ， 能夠使活塞通過進氣道， 當它們運動到一定 的位置時 ，通過 油 口 將液壓油推 出 排油 口。 斜盤的傾斜 角 度決定了柱塞泵的排量。在這里，斜盤的