Foreign language translation
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 isthe 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.
---- 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.
A, hydraulic system
Only the following three basic methods to transfer power: electrical, mechanical and fluid. Most of the application system is actually will be three methods together and get the most effective the most comprehensive system. In order to properly determine what kinds of methods, the important thing is to know the salient features of the various methods. Such as hydraulic system in long distance than mechanical system can transfer more economic power. However hydraulic system and electrical system, transfer of power than distance is short.
Hydraulic power transmission system involving motor, adjusting device, pressure and flow control, on the whole, this system includes:
1. The pump: will the dynamic role in executive ability converted into parts of the hydraulic can.
2. Valve: control pump produced fluid movement direction and the power of the size, and to perform component of the liquid flow. Power depends on the size of the flow rate and pressure control.
3. Executive parts: will hydraulic converted into usable mechanical energy.
4. Medium that is of no oil: can be compressed transfer and control, and at the same time can make body sealing parts, lubrication and cooling system.
5. Connection thing: each system components, for connection to provide power transmission fluid pressure, the liquid tank access to return to the fuel storage device .
6. The oil storage and adjusting device: to ensure that provide sufficient quality and quantity and cooling liquid.
Hydraulic system is widely used in industry, such as stamping, steel class of grinding workpiece and the general processing, agricultural machinery, mining, space technology, deep sea exploration, transportation, Marine technology, offshore gas and oil exploration industry, in short, in daily life few people don't get some from hydraulic technology benefits. Hydraulic system success and the extensive use of secret lies in its general and practical. Hydraulic power transmission wouldn't be as mechanical system that the restriction of the geometrical form by machine, in addition, hydraulic system won't like electrical system by the physical properties of the material that restrict, it to transfer power almost no amount of restrictions. For example, an
electromagnet performance by steel magnetic saturation limit, instead, hydraulic system limit the power of the subject only to the material strength limit.
Enterprise in order to improve productivity will depend more and more on automation, including the remote control and direct the production operation, processing and material handling, etc. Hydraulic power became an important part of automation, because it has the following advantages: the four main
1. The precise convenient control by operating a simple joystick and buttons, the operators of the hydraulic system and can immediately start, stop, and deceleration and can provide any power, position precision for one over ten thousand inch position control. A make the pilot rises and fall the landing gear on the hydraulic system, when the pilot to a certain direction control valves, pressure oil into hydraulic cylinder of a cavity and came down on the landing gear. The pilot to move in the opposite direction control valves, allow the oil into the hydraulic cylinder of another chamber to take back on the landing gear.
2. Add force a hydraulic system (without the use of heavy gear wheel, pulley and lever) can easily and efficiently will not an ounce of force-magnifying produce hundreds of tons of force output.
3. Constant force and constant torque can provide not only the hydraulic system with the speed of change and change is constant force or constant torque, it can drive the object from a few inches per hour to move every minute, every hour hundreds of inches from a few turned to every minute thousands of turn.
4. Simple, safe, economic overall, hydraulic system mechanical or electrical system than with fewer moving parts, therefore, they operation and convenient maintenance. This makes the system structure is compact, safe and reliable. For example, a new type of vehicle for power steering control device has been eliminated other types of steering power plant, this steering parts are included in the human control direction control valves and distributors. Due to the parts is full hydraulic pressure, no universal joint, bearing, the reduction gear, etc, this makes mechanical connection simple and compact system.
In addition, enter a small torque can produce very bad working conditions to meet the control, the operation due to space restrictions and need small the steering wheel is very important occasions, this also is necessary to reduce the driver fatigue.
Hydraulic system of other advantages including two-way movement, overload protection and stepless speed control, in the existing system of any power hydraulic system also has the largest unit quality power than.
Although hydraulic system has such a high performance, but it is not can solve all problems power transfer the panacea. Hydraulic system also some disadvantages, hydraulic oil have pollution, and leakage can't completely avoid, and if the oil leakage occurred in hot equipment, most of the hydraulic oil near can cause a fire.
Two pressure system
Air pressure system pressure gas transmission and is used to control the power, as the name of that show, air pressure system usually use air (no other gas) as a liquid medium, because the air is security, low cost and widely available, the fluid in the system components may produce electric arc light leakage of the situation that USES air as medium (especially safety.
In the air pressure system, compressor used to compress and the air supply. Compressor usually have a piston, vane and spiral type etc. Compressor is basically according to law, the ideal gas by reducing the volume of a gas to increase gas pressure. Pneumatic system usually consider using a big central air compressor as an unlimited amount of gas source, it's sort of like in the power system, as long as the plug in the socket will get electricity. Using this method, the gas pressure from transported to the whole factory air each corners of the gas pressure, through the air filter remove filth, these dirt may be damaged pneumatic components of precision components such as with valve and cylinder, then transported to each loop, and the air flowing through in order to decrease the pressure reducing valve is suitable for that one way to use. Because the air is not good lubricants (including 20% oxygen), air pressure system needs a oil sprayer the tiny oil mist injection pressure reducing valve to after air, which could help reduce the pneumatic components with exercise wear a precision.
Because of different from atmospheric air quantity of moisture, the water is harmful, and it can take away lubricant cause excessive wear and corrosion, therefore, in some situations, to use with air dryer to remove these harmful moisture. Due to atmospheric pressure system directly from too much, can produce noise, so it can vent valve and the execution component installation muffler to reduce the noise, in order to prevent the operating personnel through contact with noise and the air particles may lead to the damage.
By pneumatic system instead of hydraulic system has the following several reasons: the inertia of liquid than gas and therefore in the hydraulic system, while performing components slow down and speed up suddenly open shutoff valve, the oil quality is a potential problem, according to Newton's laws of motion (force equals mass times acceleration), produce oil accelerated motion the force needed to speed up the same volume air than the force needed many times higher. Liquid gas has more than the viscous, because it caused by internal friction more pressure and power loss; In addition, because of the hydraulic system using liquid to and atmospheric isolation, so they need special fuel tank and no leakage system design. Pneumatic system can direct platoon to use system around the air in the environment, and generally not pressure system hydraulic system is expensive.
However, because of the air compressibility, makes the air pressure system performs components can't get precise speed control and the position control. Air pressure system, the system because of compressor limited pressure is quite low (less than 250 psi), and fluid pressure can reach 10000 psi of the high and so hydraulic system can be high power system, and the pneumatic system only for small power system, the typical example has stamping, drilling, ascension, punching, clamping, assembly, riveting, material handling and logic control operation, etc.