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河南理工大學萬方科技學院
本科畢業(yè)設計(論文)中期檢查表
指導教師: 王得勝 職稱: 教授
所在院(系):機械與動力工程系 教研室(研究室):機械設計教研室
題 目
閉鎖式液力偶合器的設計
學生姓名
王加有
專業(yè)班級
08機設2班
學號
0828070051
一、 選題質量:
1, 該選題為閉鎖式液力偶合器的設計,這可以對我大學四年所學知識進行一次較為全面的練習。
2,題目的難易程度適中,并且是多個行業(yè)常用設備。
2, 題目的工作量:要求完成3張以上的A0圖紙,2.5—3萬的說明書一份。
4,所選題目緊密結合著生產實際,在我的專業(yè)范圍之內,這必對我以后從
事的生產和實踐工作有很大的幫助。
二、 開題報告完成情況:
結合現(xiàn)在的新技術和新設備等方面資料的搜集,通過對可行性的分析,我認真的進行了這次畢業(yè)設計的選題。選此題目以后,針對這個設計的題目我認真的查閱了相關的資料,我逐漸找到了設計的切入點,順利的完成了開題報告。
三、階段性成果:
1.通過對閉鎖式液力偶合器的整體了解,在加上指導老師的仔細講解,我對本次畢業(yè)設計的課題有了較為深入的理解,現(xiàn)在我已收集了大量的資料和文獻,為設計的順利完成做好了充分的準備。
2. 在老師的指導和同學的幫助下找到了設計的基本方法,開始了一些基本的結構設計。
3. 正在進行裝配圖的CAD畫圖。
四、存在主要問題:
這次是我第一次系統(tǒng)的進行設計,所以在剛開始時有些茫然不知如何著手,設計工作做的很不順利,后來找了指導老師,老師對此進行了仔細的講解,并與本組同學進行了商量,我逐漸找到是設計的切入點,我覺得這對我以后設計工作的順利進行有很大的幫助。
隨著設計的逐漸進行我又遇到了許多的新的更加復雜的問題,這些問題使我充分認識到了自己在以前學習中的不足和差距,所以我要以本次設計為契機加強自己薄弱環(huán)節(jié)的學習,爭取使我的畢業(yè)設計能夠取得好的成績,也使我所學的知識能夠在以后的工作中發(fā)揮更大的作用。
五、指導教師對學生在畢業(yè)實習中,勞動、學習紀律及畢業(yè)設計(論文)進展等方面的評語
指導教師: (簽名)
年 月 日
河南理工大學萬方科技學院
本科畢業(yè)設計(論文)開題報告
題目名稱
閉鎖式液力偶合器
學生姓名
王加有
專業(yè)班級
08機設2班
學號
0828070051
一、 選題的目的和意義:
(1) 選題的目的
在國際競爭日益加大的今天,我國企業(yè)的經營環(huán)境和經營理念等發(fā)生了極大地變化,企業(yè)爭相研究新技術并盡力把新技術轉化為生產力,這使無形資產在絕對數(shù)和相對數(shù)上都有快速、大量的增長。遠對液力耦合器行業(yè)的發(fā)展具有深的影響。在各國 貿易保護主義的時期,液力耦合器行業(yè)中技術含量低的人力密集型企業(yè),缺乏品牌的出口導向型企業(yè)面臨發(fā)展危機,而注重培養(yǎng)品牌和技術創(chuàng)新能力較強的企業(yè)將占得先機,液力耦合器行業(yè)企業(yè)如何面對新的經濟環(huán)境和政策環(huán)境,制定適合當前形勢和自身特點的發(fā)展策略與競爭策略,是液力耦合器行業(yè)企業(yè)在未來兩年我國經濟結構調整大潮中立于不敗之地的關鍵。我國對液力偶合器的應用還不是很普遍,但液力偶合器所具有的改善品質和節(jié)約能源等優(yōu)點,表明了它具有較強的生命力。隨著我國科學技術的發(fā)展,以及人們對液力偶合器的認識不斷加深,其應用領域將會日益擴大。
(2) 選題的意義
隨著我國加入WTO及全球一體化的深入我國對液力偶合器的應用還不是很普遍,但液力偶合器所具有的改善品質和節(jié)約能源等優(yōu)點,表明了它具有較強的生命力。在許多固定的機械設計上,在動力機與工作機構之間也多設有傳動裝置,其主要功能不外乎滿足工作機調速和調節(jié)功率的要求,也有的主要是為了改善起動機加速性能、過載保護、提高運用可靠性和工作壽命。因而傳動裝置的功用就不僅僅是簡單地將動力機之動力傳至走行部分,而主要在于將動力機的特性轉變?yōu)檫m應車輛運行要求的特征。液力偶合器是一種應用很廣泛的通用傳動元件,它置于動力機與工作機之間,傳遞兩者的動力。其作用似乎和聯(lián)軸器相同,但實質并不相同。在改善啟動性能、過載保護、無級變速、對載荷有自動適應性等方面,液力偶合器的特性是聯(lián)軸器所沒有的。隨著我國科學技術的發(fā)展,以及人們對液力偶合器的認識不斷加深,其應用領域將會日益擴大。在對相關著作的學習、研究中得到更多、更深層的理論知識。
二、 國內外研究綜述:
(一)國內研究現(xiàn)狀
進入二十一世紀以來,隨著我國國民經濟的高速發(fā)展,我國液力耦合器行業(yè)保持了多年高速增長,近年來,液力耦合器行業(yè)的出口也形勢喜人,2008年,全球金融危機爆發(fā),我國液力耦合器行業(yè)發(fā)展也遇到了一些困難,如國內需求下降,出口減少等,液力耦合器行業(yè)普遍出現(xiàn)了經營不景氣和利潤下降的局面,2009年,隨著我國經濟刺激計劃出臺和全球經濟走出低谷,我國液力耦合器行業(yè)也逐漸從金融危機的打擊中恢復,重新進入良性發(fā)展軌道,進入2010年,全球經濟復蘇的前景面臨波折,國內經濟結構調整的呼聲逐漸升溫,對于液力耦合器行業(yè)來說是至關重要的一年,雖然經濟整體企穩(wěn)回升,但是仍存在諸多不確定因素,本報告也將從宏觀和微觀環(huán)境對我國液力耦合器行業(yè)的發(fā)展現(xiàn)狀,政策環(huán)境、競爭策略,投資前景,市場容量,進出口形勢等方面進行全面而的分析。
(二)國外研究現(xiàn)狀
當前,國際能源日益緊張,人們不得不把注意力放到如何提高能源利用率和節(jié)約能源方面來。因此,可以在應用中節(jié)約能源的調速型液力偶合器和液力偶合器傳動裝置得到了迅速發(fā)展。由于液力偶合器傳動裝置結構復雜、技術精密、加工精度高、難度大、利潤高,因而西方各大公司競相研制生產,競爭很激烈。對于有形資產,各行業(yè)都有不同之處,需要分別進行探討。國外對有形資產要比國內更加重視,他們在理論上有很多需要我們借鑒的地方。尤其一提的是,國外對開發(fā)成本的研究日趨成熟,值得我們研究并學習。
三、 畢業(yè)設計(論文)所用的主要技術與方法:
主要采用論文分析法、案例分析法、調查法、演繹與歸納、規(guī)范和實證等科學方法,用理論分析和事實依據(jù)來加以論證,用制圖軟件繪圖,并對大量的文獻進行分析研究,并且在此基礎上進行深化創(chuàng)新,同時在實踐的基礎上進行調查訪問,對已計算出的結果進行深入探討,最終提出自己的觀點看法,撰寫成文,完成畢業(yè)論文。
四、 主要參考文獻與資料獲得情況:
(一)主要參考文獻
1. 童祖楹編著《液力偶合器》工業(yè)機械工業(yè)出版社
2. 楊乃喬,蔣麗英編著《夜里調速與節(jié)能》國防工業(yè)出版社
3. 濮良貴,紀名剛主編《機械設計》高等教育出版社
4. 孔慶華,劉傳紹主編《極限配合與測量技術基礎》同濟大學出版社
5.孫恒 ,陳作模 主編 《機械原理》西北工業(yè)大學機械原理及機械零件教研室 編
(((二)資料獲得情況
1、指導老師建議
2、通過網(wǎng)絡搜索
3、圖書館查閱資料
4、數(shù)據(jù)期刊下載
五、 畢業(yè)設計(論文)進度安排(按周說明)
第一周,選題并與指導老師確定題目
第二周,確定題目,收集相關的資料;寫畢業(yè)設計報告
第三周,開始查閱相關資料及畢業(yè)設計的格式
第四周,確定設計方案,進行結構設計
第五周,撰寫畢業(yè)設計的各個方面內容
第六周, 利用CAD開始畫一些基本的離心式摩擦離合器的相關部件
第七周 ,利用CAD開始畫一些復雜的離合器的大型圖
第八周 , 對CAD進行檢查與修改
第九周 ,完成畢業(yè)論文一稿
第十周 ,論文初稿與小組成員進行討論
第十一周 , 完成畢業(yè)論文撰寫,并進行再次修改,
第十二周 ,完成論文第二稿,并就第一稿與指導老師進行探討以便進行修改
第十三周 , 整理裝訂論文
第十四周 , 準備畢業(yè)論文答辯階段,交畢業(yè)論文
第十五周 , 按學院要求進行畢業(yè)論文答辯
六、 指導教師審批意見:
指導教師: (簽名)
年 月 日
5
河南理工大學萬方科技學院本科畢業(yè)論文
附錄:
外文資料與中文翻譯
外文資料:
Hydraulic System
Hydraulic presser drive and air pressure drive hydraulic fluid as the transmission is made according to the 17th century, Pascal's principle of hydrostatic pressure to drive the development of an emerging technology, the United Kingdom in 1795 ? Braman Joseph (Joseph Braman ,1749-1814), in London water as a medium to form hydraulic press used in industry, the birth of the world's first hydraulic press. Media work in 1905 will be replaced by oil-water and further improved.
After the World War I (1914-1918) ,because of the extensive application of hydraulic transmission, espec- ially after 1920, more rapid development. Hydraulic components in the late 19th century about the early 20th century, 20 years, only started to enter the formal phase of industrial production. 1925 Vickers (F. Vikers) the invention of the pressure balanced vane pump, hydraulic components for the modern industrial or hydraulic transmission of the gradual establishment of the foundation. The early 20th century G ? Constantimscofluct- uations of the energy carried out by passing theoretical and practical research; in 1910 on the hydraulic trans- mission (hydraulic coupling, hydraulic torque converter, etc.) contributions, so that these two areas of develo- pment.
The Second World War (1941-1945) period, in the United States 30% of machine tool applications in the hydraulic transmission. It should be noted that the development of hydraulic transmission in Japan than Europe and the United States and other countries for nearly 20 years later. Before and after in 1955, the rapid development of Japan's hydraulic drive, set up in 1956, "Hydraulic Industry." Nearly 20 to 30 years, the development of Japan's fast hydraulic transmission, a world leader.
Hydraulic transmission There are many outstanding advantages, it is widely used, such as general industr- ial use of plastics processing machinery, the pressure of machinery, machine tools, etc.; operating machinery engineering machinery, construction machinery, agricultural machinery, automobiles, etc.; iron and steel indu- stry metallurgical machinery, lifting equipment, such as roller adjustment device; civil water projects with flo- od control and dam gate devices, bed lifts installations, bridges and other manipulation of institutions; speed 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, measu- rement buoys, movements such as rotating stage; military-industrial control devices used in artillery, ship anti- rolling devices, aircraft simulation, aircraft retractable landing gear and rudder control devices and other devi- ces.
A complete hydraulic system consists of five parts, namely, power components, the implementation of co- mponents, control components, auxiliary components and hydraulic oil.
The role of dynamic components of the original motive fluid into mechanical energy to the pressure that the hydraulic system of pumps, it is to power the entire hydraulic system. The structure of the form of hydra- ulic pump gears are generally pump, vane pump and piston pump.
Implementation of components (such as hydraulic cylinders and hydraulic motors) which is the pressure of the liquid can be converted to mechanical energy to drive the load for a straight line reciprocating movement or rotational movement.
Control components (that is, the various hydraulic valves) in the hydraulic system to control and regulate the pressure of liquid, flow rate and direction. According to the different control functions, hydraulic pressure control valve can be divided into valves, flow control valves and directional control valve. Pressure control valves are divided into benefits flow valve (safety valve), pressure relief valve, sequence valve, pressure relays, etc.; flow control valves including throttle, adjusting the valves, flow diversion valve sets, etc.; directional control valve includes a one-way valve , one-way fluid control valve, shuttle valve, valve and so on. Under the control of different ways, can be divided into the hydraulic valve control switch valve, control valve and set the value of the ratio control valve.
Auxiliary components, including fuel tanks, oil filters, tubing and pipe joints, seals, pressure gauge, oil level, such as oil dollars.
Hydraulic oil in the hydraulic system is the work of the energy transfer medium, there are a variety of mineral oil, emulsion oil hydraulic molding Hop categories.
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 system and hydraulic power control signal is composed of two parts, the signal control of some parts of the hydraulic power used to drive the control valve movement. Part of the hydraulic power means that the circuit diagram used to show the different functions of the interrelationship between components. Containing the source of hydraulic pump, hydraulic motor and auxiliary components; hydraulic control part contains a variety of control valves, used to control the flow of oil, pressure and direction; operative or hydraulic cylinder with hydraulic motors, according to the actual requirements of their choice.
In the analysis and design of the actual task, the general block diagram shows the actual operation of equi - pment. Hollow arrow indicates the signal flow, while the solid arrows that energy flow.
Basic hydraulic circuit of the action sequence - Control components (two four-way valve) and the spring to reset for the implementation of components (double-acting hydraulic cylinder), as well as the extending and retracting the relief valve opened and closed . For the implementation of components and control components, presentations are based on the corresponding circuit diagram symbols, it also introduced ready made circuit diagram symbols.
Working principle of the system, you can turn on all circuits to code. If the first implementation of components numbered 0, the control components associated with the identifier is 1. Out with the implementation of components corresponding to the identifier for the even components, then retracting and implementation of components corresponding to the identifier for the odd components. Hydraulic circuit carried out not only to deal with numbers, but also to deal with the actual device ID, in order to detect system failures.
DIN ISO1219-2 standard definition of the number of component composition, which includes the following four parts: device ID, circuit ID, component ID and component ID. The entire system if only one device, device number may be omitted.
Practice, another way is to code all of the hydraulic system components for numbers at this time, components and component code should be consistent with the list of numbers. This method is particularly applicable to complex hydraulic control system, each control loop are the corresponding number with the system
With mechanical transmission, electrical transmission compared to the hydraulic drive has the following advantages:
1, a variety of hydraulic components, can easily and flexibly to layout.
2, light weight, small size, small inertia, fast response.
3, to facilitate manipulation of control, enabling a wide range of stepless speed regulation (speed range of 2000:1).
4, to achieve overload protection automatically.
5, the general use of mineral oil as a working medium, the relative motion can be self-lubricating surface, long service life;
6, it is easy to achieve linear motion /
7, it is easy to achieve the automation of machines, when the joint control of the use of electro-hydraulic, not only can achieve a higher degree of process automation, and remote control can be achieved.
The shortcomings of the hydraulic system:
1, as a result of the resistance to fluid flow and leakage of the larger, so less efficient. If not handled properly, leakage is not only contaminated sites, but also may cause fire and explosion.
2, vulnerable performance as a result of the impact of temperature change, it would be inappropriate in the high or low temperature conditions.
3, the manufacture of precision hydraulic components require a higher, more expensive and hence the price.
4, due to the leakage of liquid medium and the compressibility and can not be strictly the transmission ratio.
5, hydraulic transmission is not easy to find out the reasons for failure; the use and maintenance requirements for a higher level of technology.
In the hydraulic system and its system, the sealing device to prevent 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 personal 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, seals and sealing device is an important hydraulic equipment components. 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 the 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 (ie, sealed lips) two.
The three hydraulic system diseases
1, as a 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 pipelines at the sam- e time there is friction between the inner wall, which are a result of hydraulic the reasons for the oil tempera- ture. Temperature will lead to increased internal and external leakage, reducing its mechanical efficiency. At the same time as a result of high temperature, hydraulic oil expansion will occur, resulting in increased com- pression, so that action can not be very good control of transmission. Solution: heat is the inherent characte -ristics of the hydraulic system, not only to minimize eradication. Use a good quality hydraulic oil, hydraulic piping arrangement should be avoided 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 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 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 a good damping measures, while avoiding the external local oscillator on the system.
3, the leakage of the hydraulic system leak into inside and outside the leakage 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 hydra- ulic fluid loss, but due to leakage, the control 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 environment. Direct leakage of hydraulic oil into the environment, in addition to the system will affect the working environment, not enough pressure will cause the system to trigger a fault. Leakage into the enviro- nment of the hydraulic oil was also the danger of fire. Solution: the use of better quality seals to improve the machining accuracy of equipment.
Another: the hydraulic system for the three diseases, it was summed up: "fever, with a father拉稀" (This is the summary of the northeast people). Hydraulic system for the lifts, excavators, pumping station, dynamic, crane, and so on large-scale industry, construction, factories, enterprises, as well as elevators, lifting platforms, Deng Axle industry and so on.
Hydraulic components will be high-performance, high-quality, high reliability, the system sets the direction of development; to the low power, low noise, vibration, without leakage, as well as pollution control, water-based media applications to adapt to environmental requirements, such as the direction of development; the development of highly integrated high power density, intelligence, mechatronics and micro-light mini-hydraulic components; active use of new techniques, new materials and electronics, sensing and other high-tech.
---- Hydraulic coupling to high-speed high-power and integrated development of hydraulic transmission equ- ipment, development of water hydraulic coupling medium speed and the field of automotive applications to develop hydraulic reducer, improve product reliability and working hours MTBF; hydraulic torque converter to the development of high-power products, parts and components to improve the manufacturing process tech -nology to improve reliability, promote computer-aided technology, the development of hydraulic torque con- verter and power shift transmission technology supporting the use of ; Clutch fluid viscosity should increase the quality of products, the formation of bulk to the high-power and high-speed direction.
Pneumatic Industry:
---- Products to small size, light weight, low power consumption, integrated portfolio of development, the implementation of the various types of components, compact structure, high positioning accuracy of the direction of development; pneumatic components and electronic technology, to the intelligent direction of development; component performance to high-speed, high-frequency, high-response, high-life, high temp- erature, high voltage direction, commonly used oil-free lubrication, application of new technology, new technology and new materials.
(1) used high-pressure hydraulic components and the pressure of continuous work to reach 40Mpa, the maximum pressure to achieve instant 48Mpa;
(2) diversification of regulation and control;
(3) to further improve the regulation performance, increase the efficiency of the powertrain;
(4) development and mechanical, hydraulic, power transmission of the composite portfolio adjustment gear;
(5) development of energy saving, energy efficient system function;
(6) to further reduce the noise;
(7) Application of Hydraulic Cartridge Valves thread technology, compact structure, to reduce the oil spill.
中文翻譯:
液壓系統(tǒng)
液壓傳動和氣壓傳動稱為流體傳動,是根據(jù)17世紀帕斯卡提出的液體靜壓力傳動原理而發(fā)展起來的一門新興技術,1795年英國約瑟夫?布拉曼(Joseph Braman,1749-1814),在倫敦用水作為工作介質,以水壓機的形式將其應用于工業(yè)上,誕生了世界上第一臺水壓機。1905年將工作介質水改為油,又進一步得到改善。
第一次世界大戰(zhàn)(1914-1918)后液壓傳動廣泛應用,特別是1920年以后,發(fā)展更為迅速。液壓元件大約在 19 世紀末 20 世紀初的20年間,才開始進入正規(guī)的工業(yè)生產階段。1925 年維克斯(F.Vikers)發(fā)明了壓力平衡式葉片泵,為近代液壓元件工業(yè)或液壓傳動的逐步建立奠定了基礎。20 世紀初康斯坦丁?尼斯克(G?Constantimsco)對能量波動傳遞所進行的理論及實際研究;1910年對液力傳動(液力聯(lián)軸節(jié)、液力變矩器等)方面的貢獻,使這兩方面領域得到了發(fā)展。
第二次世界大戰(zhàn)(1941-1945)期間,在美國機床中有30%應用了液壓傳動。應該指出,日本液壓傳動的發(fā)展較歐美等國家晚了近 20 多年。在 1955 年前后 , 日本迅速發(fā)展液壓傳動,1956 年成立了“液壓工業(yè)會”。近20~30 年間,日本液壓傳動發(fā)展之快,居世界領先地位。
液壓傳動有許多突出的優(yōu)點,因此它的應用非常廣泛,如一般工業(yè)用的塑料加工機械、壓力機械、機床等;行走機械中的工程機械、建筑機械、農業(yè)機械、汽車等;鋼鐵工業(yè)用的冶金機械、提升裝置、軋輥調整裝置等;土木水利工程用的防洪閘門及堤壩裝置、河床升降裝置、橋梁操縱機構等;發(fā)電廠渦輪機調速裝置、核發(fā)電廠等等;船舶用的甲板起重機械(絞車)、船頭門、艙壁閥、船尾推進器等;特殊技術用的巨型天線控制裝置、測量浮標、升降旋轉舞臺等;軍事工業(yè)用的火炮操縱裝置、船舶減搖裝置、飛行器仿真、飛機起落架的收放裝置和方向舵控制裝置等。
一個完整的液壓系統(tǒng)由五個部分組成,即動力元件、執(zhí)行元件、控制元件、輔助元件和液壓油。
動力元件的作用是將原動機的機械能轉換成液體的壓力能,指液壓系統(tǒng)中的油泵,它向整個液壓系統(tǒng)提供動力。液壓泵的結構形式一般有齒輪泵、葉片泵和柱塞泵。
執(zhí)行元件(如液壓缸和液壓馬達)的作用是將液體的壓力能轉換為機械能,驅動負載作直線往復運動或回轉運動。
控制元件(即各種液壓閥)在液壓系統(tǒng)中控制和調節(jié)液體的壓力、流量和方向。根據(jù)控制功能的不同,液壓閥可分為壓力控制閥、流量控制閥和方向控制閥。壓力控制閥又分為益流閥(安全閥)、減壓閥、順序閥、壓力繼電器等;流量控制閥包括節(jié)流閥、調整閥、分流集流閥等;方向控制閥包括單向閥、液控單向閥、梭閥、換向閥等。根據(jù)控制方式不同,液壓閥可分為開關式控制閥、定值控制閥和比例控制閥。
輔助元件包括油箱、濾油器、油管及管接頭、密封圈、壓力表、油位油溫計等。
液壓油是液壓系統(tǒng)中傳遞能量的工作介質,有各種礦物油、乳化液和合成型液壓油等幾大類。
液壓系統(tǒng)的作用就是幫助人類做工。主要是由執(zhí)行元件把壓力變成轉動或往復運動。
液壓系統(tǒng)由信號控制和液壓動力兩部分組成,信號控制部分用于驅動液壓動力部分中的控制閥動作。
液壓動力部分采用回路圖方式表示,以表明不同功能元件之間的相互關系。液壓源含有液壓泵、電動機和液壓輔助元件;液壓控制部分含有各種控制閥,其用于控制工作油液的流量、壓力和方向;執(zhí)行部分含有液壓缸或液壓馬達,其可按實際要求來選擇。
在分析和設計實際任務時,一般采用方框圖顯示設備中實際運行狀況。 空心箭頭表示信號流,而實心箭頭則表示能量流。
基本液壓回路中的動作順序—控制元件(二位四通換向閥)的換向和彈簧復位、執(zhí)行元件(雙作用液壓缸)的伸出和回縮以及溢流閥的開啟和關閉。 對于執(zhí)行元件和控制元件,演示文稿都是基于相應回路圖符號,這也為介紹回路圖符號作了準備。
根據(jù)系統(tǒng)工作原理,您可對所有回路依次進行編號。如果第一個執(zhí)行元件編號為0,則與其相關的控制元件標識符則為1。如果與執(zhí)行元件伸出相對應的元件標識符為偶數(shù),則與執(zhí)行元件回縮相對應的元件標識符則為奇數(shù)。 不僅應對液壓回路進行編號,也應對實際設備進行編號,以便發(fā)現(xiàn)系統(tǒng)故障。
DIN ISO1219-2標準定義了元件的編號組成,其包括下面四個部分:設備編號、回路編號、元件標識符和元件編號。如果整個系統(tǒng)僅有一種設備,則可省略設備編號。
實際中,另一種編號方式就是對液壓系統(tǒng)中所有元件進行連續(xù)編號,此時,元件編號應該與元件列表中編號相一致。 這種方法特別適用于復雜液壓控制系統(tǒng),每個控制回路都與其系統(tǒng)編號相對應與機械傳動、電氣傳動相比,液壓傳動具有以下優(yōu)點:
1、液壓傳動的各種元件,可以根據(jù)需要方便、靈活地來布置。
2、重量輕、體積小、運動慣性小、反應速度快。
3、操縱控制方便,可實現(xiàn)大范圍的無級調速(調速范圍達2000: 1)。
4、可自動實現(xiàn)過載保護。
5、一般采用礦物油作為工作介質,相對運動面可自行潤滑,使用壽命長;
6、很容易實現(xiàn)直線運動/
7、很容易實現(xiàn)機器的自動化,當采用電液聯(lián)合控制后,不僅可實現(xiàn)更高程度的自動控制過程,而且可以實現(xiàn)遙控。
液壓系統(tǒng)的缺點:
1、由于流體流動的阻力和泄露較大,所以效率較低。如果處理不當,泄露不僅污染場地,而且還可能引起火災和爆炸事故。
2、由于工作性能易受到溫度變化的影響,因此不宜在很高或很低的溫度條件下工作。
3、液壓元件的制造精度要求較高,因而價格較貴。
4、由于液體介質的泄露及可壓縮性影響,不能得到嚴格的傳動比。
5、液壓傳動出故障時不易找出原因;使用和維修要求有較高的技術水平。
在液壓系統(tǒng)及其系統(tǒng)中,密封裝置用來防止工作介質的泄漏及外界灰塵和異物的侵入。其中起密封作用的元件,即密封件。外漏會造成工作介質的浪費,污染機器和環(huán)境,甚至引起機械操作失靈及設備人身事故。內漏會引起液壓系統(tǒng)容積效率急劇下降,達不到所需要的工作壓力,甚至不能進行工作。侵入系統(tǒng)中的微小灰塵顆粒,會引起或加劇液壓元件摩擦副的磨損,進一步導致泄漏。
因此,密封件和密封裝置是液壓設備的一個重要組成部分。它的工作的可靠性和使用壽命,是衡量液壓系統(tǒng)好壞的一個重要指標。除間隙密封外,都是利用密封件,使相鄰兩個偶合表面間的間隙控制在需要密封的液體能通過的最小間隙以下。在接觸式密封中,分為自封式壓緊型密封和自封式自緊型密封(即唇形密封)兩種。
液壓系統(tǒng)的三大頑疾
1、發(fā)熱 由于傳力介質(液壓油)在流動過程中存在各部位流速的不同,導致液體內部存在一定的內摩擦,同時液體和管路內壁之間也存在摩擦,這些都是導致液壓油溫度升高的原因。溫度升高將導致內外泄漏增大,降低其機械效率。同時由于較高的溫度,液壓油會發(fā)生膨脹,導致壓縮性增大,使控制動作無法很好的傳遞。解決辦法:發(fā)熱是液壓系統(tǒng)的固有特征,無法根除只能盡量減輕。使用質量好的液壓油、液壓管路的布置中應盡量避免彎頭的出現(xiàn)、使用高質量的管路以及管接頭、液壓閥等。
2、振動 液壓系統(tǒng)的振動也是其痼疾之一。由于液壓油在管路中的高速流動而產生的沖擊以及控制閥打開關閉過程中產生的沖擊都是系統(tǒng)發(fā)生振動的原因。強的振動會導致系統(tǒng)控制動作發(fā)生錯誤,也會使系統(tǒng)中一些較為精密的儀器發(fā)生錯誤,導致系統(tǒng)故障。解決辦法:液壓管路應盡量固定,避免出現(xiàn)急彎。避免頻繁改變液流方向,無法避免時應做好減振措施。整個液壓系統(tǒng)應有良好的減振措施,同時還要避免外來振源對系統(tǒng)的影響。
3、泄漏 液壓系統(tǒng)的泄漏分為內泄漏和外泄漏。內泄漏指泄漏過程發(fā)生在系統(tǒng)內部,例如液壓缸活塞兩邊的泄漏、控制閥閥芯與閥體之間的泄漏等。內泄漏雖然不會產生液壓油的損失,但是由于發(fā)生泄漏,既定的控制動作可能會受到影響,直至引起系統(tǒng)故障。外泄漏是指發(fā)生在系統(tǒng)和外部環(huán)境之間的泄漏。液壓油直接泄漏到環(huán)境中,除了會影響系統(tǒng)的工作環(huán)境外,還會導致系統(tǒng)壓力不夠引發(fā)故障。泄漏到環(huán)境中的液壓油還有發(fā)生火災的危險。解決辦法:采用質量較好的密封件,提高設備的加工精度。
另:對于液壓系統(tǒng)這三大頑疾,有人進行了總結:“發(fā)燒、拉稀帶得瑟”(這位總結者是東北人)。液壓系統(tǒng)用于升降機,挖掘機,泵站,強夯機,起重機,等等大型工業(yè),建筑,工廠,企業(yè),還有升降機,升降平臺,登車橋等等行業(yè)。
液壓元件將向高性能、高質量、高可靠性、系統(tǒng)成套方向發(fā)展;向低能耗、低噪聲、振動、無泄漏以及污染控制、應用水基介質等適應環(huán)保要求方向發(fā)展;開發(fā)高集成化高功率密度、智能化、機電一體化以及輕小型微型液壓元件;積極采用新工藝、新材料和電子、傳感等高新技術。
---- 液力偶合器向高速大功率和集成化的液力傳動裝置發(fā)展,開發(fā)水介質調速型液力偶合器和向汽車應用領域發(fā)展,開發(fā)液力減速器,提高產品可靠性和平均無故障工作時間;液力變矩器要開發(fā)大功率的產品,提高零部件的制造工藝技術,提高可靠性,推廣計算機輔助技術,開發(fā)液力變矩器與動力換檔變速箱配套使用技術;液粘調速離合器應提高產品質量,形成批量,向大功率和高轉速方向發(fā)展。
氣動行業(yè):
----產品向體積小、重量輕、功耗低、組合集成化方向發(fā)展,執(zhí)行元件向種類多、結構緊湊、定位精度高方向發(fā)展;氣動元件與電子技術相結合,向智能化方向發(fā)展;元件性能向高速、高頻、高響應、高壽命、耐高溫、耐高壓方向發(fā)展,普遍采用無油潤滑,應用新工藝、新技術、新材料。
(1)采用的液壓元件高壓化,連續(xù)工作壓力達到40Mpa,瞬間最高壓力達到48Mpa;
(2)調節(jié)和控制方式多樣化;
(3)進一步改善調節(jié)性能,提高動力傳動系統(tǒng)的效率;
(4)發(fā)展與機械、液力、電力傳動組合的復合式調節(jié)傳動裝置;
(5)發(fā)展具有節(jié)能、儲能功能的高效系統(tǒng);
(6)進一步降低噪聲;
(7)應用液壓螺紋插裝閥技術,緊湊結構、減少漏油。
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