氣壓傳動外文翻譯

1、<p>　　畢業(yè)設計(論文)外文翻譯</p><p>　　學生姓名 專業(yè)班級 機械06-4班 　 </p><p>　　指導教師 職 稱 　 </p><p>　　所在單位 機械工程學院 　 </p><

2、p>　　教學部主任 </p><p>　　完成日期 2010年6月16日</p><p>　　Pneumatic Transmission</p><p>　　Similar to hydraulic transmission, pneumatic transmission pe

3、rforms the function of energy transfer and control by the medium of flow. They have a great deal in common in the aspects of working principle, components’ structure, system composition and graphic symbol. The readers sh

4、ould notice their differences.A pneumatic system incorporates the following components and devices:</p><p>　　(1)Air supply devices: They include pressure generation devices, air regeneration and storing devi

5、ces, F. R. L. (air filter, pressure reducing valve and oil mist lubricator) combination, etc. It provides qualified compressed air for pneumatic systems.</p><p>　　(2)Actuators: They convert the compressed ai

6、r pressure into mechanical energy, such as air cylinders and air motors.</p><p>　　(3)Control elements: They are used to control the pressure, flow rate and moving direction for the components, such as valves

7、.</p><p>　　(4)Pneumatic attachments: They incorporate the components which are used to cool, silence, purify, and lubricate compressed air and those to joint each component.</p><p>　　1.1 Air Su

8、pply Devices</p><p>　　Air supply devices are used to provide compressed air for pneumatic systems. An air supply device is an important part of a pneumatic system, which supplies qualified compressed air (wi

9、th a certain lever of pressure, flow rate and purification) for the pneumatic system. Generally, for the delivery surpasses or equals 6 - 12m³/min, a compressed air station is needed. But for the delivery less than

10、6 - 12m³/min.the air compressor can be mounted besides the pneumatic equipment directly.</p><p>　　An air supply device incorporates four parts: pressure generation devices, air regeneration and storing

11、devices, air lines and F. R. L. combination.</p><p>　　Normally the first two parts are located in compressed air station as a center to supply gas in industry or workshop.</p><p>　　Air compresso

12、r: pressurize atmospheric air; </p><p>　　Cooler: cool compressed air; condense water and hydrocarbon vapours;</p><p>　　Oil and water separator: remove gross solid and liquid particulates;</p&

13、gt;<p>　　Receivers: air storage; settling chamber for particulates; cool air;</p><p>　　Air dryer: further reduce water and oil vapour content;</p><p>　　Air filter: further remove desiccan

14、t dust and fines.</p><p>　　In a pneumatic system, the compressed air flowing out from receiver is for general use and that from another receiver is for special use (such us the control circuits composed by p

15、neumatic meters or fluidic elements).</p><p>　　1.1.1 Pressure generation devices</p><p>　　Compressor is one type of pressure generation devices, which converts mechanical energy into pressure e

16、nergy. Compressors can be classified according to their working principles, structures or performance properties.</p><p>　　(1)    According to working principles: Displacement and dynamic

17、;</p><p>　　(2)    According to structures</p><p>　　(3)    According to output pressures:</p><p>　　Low pressure (0.2 - 1.0MPa), medium pressur

18、e (1.0 - 10MPa), high pressure (10 - 100MPa), super high pressure (>100MPa).</p><p>　　(4)According to output flow rates(delivery): </p><p>　　Mini (<1m³/min), small (1 - 10 m³/min

19、), medium (10 - 100 m³/min), large (>100 m³/min). 1.1.2 Purification and storing devices and equipments for compressed air</p><p>　　Normally, purification equipments for compressed air involve:

20、 cooler, a moisture separator, a receiver and an air dryer.</p><p>　　1.1.2.1    Cooler:cooler is usually set at the outlet port of the compressor and serves as a heat exchanger to cool co

21、mpressed air after leaving the compressor. Cooling can reduce an air temperature of 120 - 150°C to 40 - 50°C. Coolers can be further classified based on their arrangement: coil tubular type, series tubular type

22、, thermosyphon system and tube drive type. There are two types of cooling: water cooling and air cooling.</p><p>　　1.1.2.2 Moisture separator: it is used to separate the impurities such as condensed water an

23、d oil stain from the compressed air to gain an initial purified compressed air. When compressed air enters the separator, its flow rate and velocity will change sharply and the impurities with a higher density initially

24、purified. The configurations of separators incorporate: ring revolving type, strike and return type, centrifugal rotary type, water-bath type, etc. This is a strike and return type moistur</p><p>　　1.1.2.3&#

25、160;   Receiver: it is used to store a certain amount of compressed air, reduce its pressure fluctuation and provide gas continuously and stably. There are two types of receivers: horizontal and vertical.

26、Vertical type receivers are more often adopted to save room.</p><p>　　Nowadays, the arrangement with the combination of cooler, moisture separator and receiver has found many applications.</p><p&g

27、t;　　1.1.2.4 Air dryer:the compressed air after having been purified and treated by the cooler, moisture separator and receiver can meet the requirements of general pneumatic systems. But for other precise devices such as

28、 precise machines and meters, the compressed air must be further purified or treated. Air dryers have the function of further removing water vapour, oil mist and other particle impurities with mini diameter. Methods of a

29、ir drying incorporate mechanical, centrifugal force, refrigerati</p><p>　　1.1.3 F. R. L. combination</p><p>　　F. R. L. combination is short for the combination of an air filter, a pressure redu

30、cing valve and an oil mist lubricator. First comes the air filter (secondary filter), followed by the pressure reducing valve and the oil mist lubricator is set behind (see from the air inlet direction). F. R. L. combina

31、tion supplies better quality compressed air for pneumatic components or systems.</p><p>　　1.1.3.1    Air filter: An air filer is used to remove dust, impurities, oil stain and separate wa

32、ter vapour from the compressed air. As compressed air passes the inlet port and enters the filter section, it passes through the directional louvers forcing it into a whirling flow pattern. Liquid particles and heavy sol

33、id are thrown against the inside wall of the bowl by centrifugal force. The liquid then runs to the bottom of the bowl where it is either removed by the automatic drain assembly or by</p><p>　　1.1.3.2 Oil mi

34、st lubricator: An oil mist lubricator is one type of oiling devices. The compressed air enters the lubricator, ejecting the oil lubricant into a spraying fog which flows with the compressed air into the components that n

35、eed to be lubricated.</p><p>　　1.1.3.3 Pressure reducing valve: Pressure reducing valve is one component of F. R. L. combination. It is used to reduce the pressure of compressed air from gas source to meet t

36、he pressure requirement of a given pneumatic system. The pressure after a pressure reducing valve is kept stable, avoiding both the influences of gas-source pressure fluctuation and its output flow rate change. Like hydr

37、aulic transmission, the pressure regulating methods of pressure reducing valves incorporate: direct acti</p><p>　　1.2 Pneumatic Actuators</p><p>　　1.2.1 Pneumatic cylinders</p><p>

38、;　　1.2.1.1 Operations and functions: The operations and functions of common cylinders are similar to those of hydraulic cylinders. Only some special cylinders are discussed in this section.</p><p>　　(1) 

39、;   Diaphragm cylinders: A diaphragm cylinder is basically a large diameter, short stroke cylinder fitted with a diaphragm instead of a piston. The construction usually takes the form of a pair of shallow

40、convex housings, with a diaphragm sandwiched between them and a piston rod attached to the diaphragm. They are usually of single-rod type, either single-acting with spring return or double-acting.</p><p>　　D

41、iaphragm cylinders are capable of generating very large forces with very short strokes and are commonly called thrusters. The theoretical thrust available is equal to the product of the applied air pressure and effective

42、 diaphragm area. The stroke is normally limited to a maximum of about one-third of the cylinder diameter.</p><p>　　Diaphragm cylinders are simple, concise in design, low cost, small leakage, easy to manufact

43、ure and maintain. But they have short strokes due to the limitation of the diaphragm deformation. Diaphragm cylinders are mainly used in pneumatic clamping devices and the working occasions with short stroke.</p>

44、<p>　　(2)    Air-hydraulic cylinders: When outside load is large enough, there may occur poor stability to the movement of a unique pneumatic cylinder. This can be solved by an air-hydraulic cyli

45、nder. Hydro-pneumatic working is achieved by mechanically coupling a pneumatic cylinder and a low-pressure hydraulic cylinder so that they have a common movement normally initiated by compressed air applied to the air cy

46、linder. Liquids have slight compressibility and air flow is easy to control, which leads to</p><p>　　The normal configuration is back-to-back mounting with a common piston rod. The piston speed can be adjust

47、ed by throttle valve. Reservoir and check valve are used for oil compensation. In this circuit, the pneumatic cylinder only provides driving force and the stable movement depends upon the hydraulic cylinder by adjusting

48、throttle valve. This circuit does not need any hydraulic source and thus is low in cost. In addition, it makes full use of pneumatic and hydraulic and thus finds many applica</p><p>　　(3)   &#

49、160;Rodless cylinders: Recently-developed rodless cylinders provide an ideal solution for long stroke applications. In one rodless design the cylinder barrel has a slit along the barrel and the piston in the barrel is co

50、nnected directly through the slit to a mounting on the outside of the cylinder.</p><p>　　Thus when the piston is moved by applying air on either side, the load connected to the external mounting is moved. Th

51、e problem of providing a continuous and moving seal between the piston and sign handle long strikes effectively but can also accept lateral loading at the mounting point.</p><p>　　This is an illustration of

52、the construction of one type of rodless cylinder. The drive from the piston to the carriage is via a substantial drive tongue which passes through the barrel slot. This drive tongue forms the center part of this yoke whi

53、ch is incorporated in the carriage extrusion. The piston halves are pinned to the lower part of this yoke, joining the piston to the carriage.</p><p>　　The volume between the piston seals, containing the yok

54、e, is at atmospheric pressure. The pressure and dust slot seals are unclipped and parted by cam shapes in the yoke within this non-pressurized section and by the advancing movement of the piston carriage assembly along t

55、he cylinder.</p><p>　　After unclipping, the internal pressure seal slides under the lower part of the yoke adjacent to the piston halves, while the external dust seal slides over the upper part of the yoke w

56、ithin the carriage. The pressure and dust slot seals are then pressed together and re-clipped by the spring roller assembly in the carriage and the ramp shape of the piston and by the retreating movement of the piston ca

57、rriage assembly along the cylinder body. Thus the drive is taken up from the piston to the carr</p><p>　　(4) Impact cylinders: An impact cylinder is one arranged so that the speed developed is high enough fo

58、r impact work, such as forging, piercing, etc. It converts the pressure energy of the compressed air into piston’s high speed (more than ten meters per second) motion energy in a very short time.</p><p>　　Th

59、is is an impact cylinder design. Compared with common cylinders, there is an extra middle lid (fitted with the cylinder body) with nozzle and exhausting small orifice. The cylinder is divided into three chambers by this

60、middle lid and piston. For the sake of analysis, the working process can be simply divided into three steps.</p><p>　　1)    Reset. The piston rod chamber is charged with air and the air i

61、n energy storing chamber exhausts out. The piston moves up until the seal gasket on the piston seals nozzle on middle lid. Piston chamber connects with the atmospheric via exhausting port. The pressure in chamber builds

62、up to air source pressure, while the pressure in chamber falls down to atmospheric pressure.</p><p>　　2)    Energy storage. When air enters chamber, it passes through the nozzle and acts

63、on the piston. The area of the nozzle is so small that the air pressure cannot overcome the resultant of the up thrust (produced by air exhausting in the piston rod chamber) and the friction against the cylinder. The noz

64、zle is still closed and the pressure in chamber builds up gradually.</p><p>　　3)    Impacting. When the ratio of the pressure in chamber to that in the piston rod chamber surpasses the ra

65、tio of the acting area in the piston rod chamber to the nozzle area the piston moves down to open the nozzle. Immediately this happens the compressed air accumulated in chamber acts on the whole of the piston via the noz

66、zle, causing the piston to move down rapidly due to the high pressure difference of the piston rid. Because of the large thrust produced by this high pressure difference, </p><p>　　1.2.2 Air motors</p>

67、;<p>　　Air motors are pneumatic actuators which convert compressed air energy into rotating motion. Based on arrangement, they can be divided into vane type, piston type, gear type, diaphragm type, etc.</p>

68、<p>　　1.2.2.1    Operation and characteristics of air motors</p><p>　　(1)Vane motors: This is a simple vane motor operation. The rotor and the vanes are the only moving parts. The r

69、otor is mounted offset in the casing, as can be seen. Air is admitted when the crescent shaped chamber is increasing in volume and delivered when decreasing. Torque is developed by pressure difference on the vanes, drivi

70、ng the rotor to turn in a counter clockwise direction for this motor. The air exhausts through orifices C and B. This direction of the rotor can be changed by merely cha</p><p>　　Small size motors are used f

71、or hand tools such as drills, grinders and screwdrivers. Larger sizes are used for winches, pump drivers, and drive motors on pneumatic drill rigs and general industrial applications.</p><p>　　(2)Radial pist

72、on motors: Piston motors operate at much lower speeds than vane motors because of the greater inertia of the reciprocating parts.</p><p>　　The typical radial motor has all connecting rids mounted on a common

73、 crank (crank and connecting rod mechanism). The compressed air passes through the distribution valve from the inlet port and then enters the cylinder, driving part of the pistons to move reciprocating. The pistons’ reci

74、procating motion converts into crankshaft rotation through the crank and connecting rod mechanism. The crankshaft then drives the distribution valve which fixed on it to move simultaneously, causing the compresse</p&g

75、t;<p>　　(3)Diaphragm motors: Diaphragm motors are basically an application of diaphragm cylinders. The cylinder’s reciprocating motion converts into the ratchet wheel’s intermittent rotary output pressibility, i.e

76、. the output torque falls off with the increase of intermittent transmission speed under the constant working pressure.</p><p>　　1.2.2.2    Selection and application of air motors</p&g

77、t;<p>　　(1)Air motors’ selection: The selection of air motors is mainly base on its loaded conditions. In variable load occasions, the speed range and the torque needed to meet working conditions are principally c

78、onsidered. Working speed is also an important factor for constant load occasions. Other factors must be considered except for the above performance-related factors, such as working pressure, gas consumption installation

79、type, etc.</p><p>　　(2)Air motors’ application: Air motors find more and more applications as the developing of the productivity. They can be used in all walks of life, particularly applicable for the occasi

80、ons which require safety-needed, stepless speed changing, frequent direction changing for startup, resistant exploding, and load startup and that easy to be overloaded. They are equally suitable the harsh environment wit

81、h moisture, high temperature, vibration or that inconvenient to operate directly, such as min</p><p>　　(3)Air motors’ lubricating: The working medium of air cannot provide lubrication itself, so additional l

82、ubricants are needed in air motors. Proper used and nice lubricating will extend air motors’ use life, with the second repair time of 2500 - 3000h or longer. The common way to lubricate is to set an oil mist lubricator b

83、efore the control valve in the air motor and supply oil in time; the lubricant will enter the system with the compressed air to accomplish lubricating purposed.</p><p>　　1.3 Pneumatic control elements</p

84、><p>　　An important item in a compressed air layout is a regulating valve which ensures the desired pressure, flow rate and direction in the system. The first important function of these valves is for safety; t

85、he second function is to provide for a part of the system to operate at a lower pressure than the main supply. There are various types of regulating valves; generally they can be divided into three main categories define

86、d by the functions they perform: pressure control, flow control and direction</p><p>　　The pneumatic fixed value switching regulating valves are similar to hydraulic regulating valves; there are also pneumat

87、ic proportional regulating valves and pneumatic servo-control valves. The recently-developed valve terminal has the advantages of concise construction, easy to install and maintain, high degree of modularization, and can

88、 achieve centralized control in medium or small pneumatic systems.</p><p>　　1.4 Pneumatic attachments</p><p>　　1.4.1 Mufflers</p><p>　　Unlike hydraulic circuits, there are no retu

89、rn pipelines in pneumatic circuits. The compressed air exhausts to the atmospheric directly after having been used. The air will sharply expend due to high pressure difference and produce serious exhausting noise. Usuall

90、y a muffler is set at the discharge port to reduce the velocity and power of the jet noise by means of damp or increasing exhausting area.</p><p>　　Three types of muffler are available: absorptive mufflers,

91、expansive mufflers, expansive and absorptive mufflers. This is an absorptive muffler structure. The muffler body is made of multi-hole absorptive material, sintered by copper or polystyrene bean. Today absorptive muffler

92、s are also most wildly used.</p><p>　　1.4.2 Pipeline connectors</p><p>　　Pipeline connectors incorporate tubes and pipe fittings. There are rigid tubes and hose tubes. Pipe couplings include bi

93、te type tube fittings, flared type tube fittings, corpling of borsing and quick release fittings.</p><p><b>　　氣壓傳動</b></p><p>　　類似與液壓傳動，氣壓傳動通過介質的流量來執(zhí)行能量傳遞和控制的功能。在工作原理、組成結構、系統(tǒng)組成及圖形符號等

94、方面，他們有許多共同之處。讀者應該注意到他們的不同之處。氣動系統(tǒng)包含以下組件和設備：</p><p>　　(1) 氣壓發(fā)生裝置：他們包括壓力產生設備、空氣再生和儲存設備，FRL（空氣過 濾器、減壓閥和油霧潤滑）組件，等等。它為氣動系統(tǒng)提供合格的壓縮氣體。</p><p>　　(2) 執(zhí)行元件：他們把壓縮空氣的壓力能轉變?yōu)闄C械能，例如氣動缸和氣動馬達。</p>

95、<p>　　(3) 控制元件：他們是被用來控制壓縮氣體壓力、流速、和流動方向，是執(zhí)行機構按要求工作，如氣動閥。</p><p>　　(4) 氣動輔件：氣動輔件包含使壓縮空氣冷卻、消聲、凈化和潤滑以及用于連接各元件所需要的一些裝置。</p><p><b>　　1.1氣壓發(fā)生裝置</b></p><p>　　氣壓發(fā)生裝置是用來為氣動系

96、統(tǒng)提供壓縮氣體的。一套氣體發(fā)生裝置是氣動系統(tǒng)的重要組成部分之一，為氣動系統(tǒng)提供合格的壓縮空氣（具有一定的壓力、流量和凈化過的）。一般來說，對于流量超過或等于6～12，空氣壓縮站是必須具備的。但對輸出流量少于6～12，空氣壓縮機可直接安裝在氣動裝置旁。</p><p>　　氣壓發(fā)生裝置包括四個部分：壓力產生裝置，空氣再生和儲存裝置，空氣流和FRL組件（空氣過濾器、減壓閥等）。通常首先把前倆部分安裝在空氣壓縮站的中心

97、，為工廠或車間供壓縮空氣</p><p>　　空氣壓縮機：給空氣加壓；</p><p>　　冷卻器:冷卻壓縮氣體；濃縮水和碳氫化合物蒸汽；</p><p>　　油水分離器：分離排除固體和液體微粒雜質；</p><p>　　貯氣罐：存儲壓縮空氣；沉降微粒雜質；冷卻壓縮氣體；</p><p>　　空氣干燥器：進一步減少水分

98、和油分的含量。</p><p>　　在一套氣動系統(tǒng)中，從貯氣罐流出的壓縮氣體適合一般用，然而從另一個貯氣罐流出的適合特殊用途（例如用來控制由氣動儀表或射流元件組成的回路）。</p><p>　　1.1.1氣壓發(fā)生裝置</p><p>　　壓縮機是一種氣壓發(fā)生裝置，它將機械能轉化為氣體壓力能的裝置?？諝鈮嚎s機可以按他們的工作原理，結構，工作性能進行分類。</p&

99、gt;<p>　　(1) 按工作原理：容積型和速度型；</p><p><b>　　(2) 按結構</b></p><p>　　(3) 按照輸出的壓力：低壓(0.2～1.0MPa)，中壓（1.0～10MPa）,高壓（10～100MPa）,超高壓（100MPa）。</p><p>　　(4) 按照輸出的流量（排量）：微型（），小型（

100、1~10），中型（10~100），大型（100）。</p><p>　　1.1.2壓縮空氣的凈化和貯氣設備：</p><p>　　一般來說，壓縮空氣的凈化裝置包括：冷卻器，水分離器，貯氣罐和一個干燥器。</p><p>　　1.1.2.1 冷卻器</p><p>　　冷卻器經常布置在壓縮機的排氣口，作為一個熱交換器來冷卻離開壓縮機的后的壓縮氣