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Hydraulic transmission and pneumatic transmission are collectively called fluid transmission
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  • Updated: 2020-01-14
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  • Hydraulic transmission and pneumatic transmission are collectively referred to as fluid transmission dynamics, and there is a brief introduction to the formation process of hydraulic pressure. Hydraulic technology is generally used in heavy, large and extra-large equipment, such as rolling mill reduction systems and continuous casting mill reduction systems in the metallurgical industry; High-speed response occasions, such as aircraft tail rudder control, ship steering control, high-speed response servo system, and other engineering machinery, are shock-resistant and require high power. Generally, hydraulic systems are used. These are the three largest areas for applying hydraulic technology. Basic Principles of Hydraulic Transmission In principle, the most basic principle on which hydraulic transmission is based is the Pascal principle, that is, the pressure across the liquid is the same. In this way, in a balanced system, the pressure exerted on the smaller piston It is relatively small, and the pressure exerted by the large piston is relatively large, which can keep the liquid still. Therefore, through the transfer of liquid, different pressures on different ends can be obtained, so that the purpose of a transformation can be achieved. The hydraulic jacks we commonly use are based on this principle to achieve force transmission. The components needed in hydraulic transmission are mainly power components, actuators, control components, auxiliary components, etc. Among them, hydraulic power components are components that generate power for hydraulic systems, and mainly include various hydraulic pumps. The hydraulic pump relies on the principle of volume change to work, so it is generally called a volume hydraulic pump. Gear pump is the most common type of hydraulic pump. It moves liquid through the rotation of two meshing gears. Other hydraulic pumps include vane pumps and plunger pumps. The main issues to pay attention to when selecting a hydraulic pump include energy consumption, efficiency, and noise reduction. Hydraulic actuators are devices used to perform the conversion of hydraulic energy provided by hydraulic pumps into mechanical energy, mainly including hydraulic cylinders and hydraulic motors. Hydraulic motor is a device that does the opposite work to a hydraulic pump, that is, the energy conversion of hydraulic pressure is called mechanical energy, so as to perform external work.
    Hydraulic control elements are used to control the direction of liquid flow, the level of pressure, and the expected control of the flow to meet specific work requirements. It is precisely because of the flexibility of the hydraulic control components that the hydraulic control system can perform different activities. Hydraulic control elements can be divided into pressure control valves, flow control valves, and directional control valves according to the purpose. According to the operation mode, it can be divided into manual operation valve, mechanical operation method, electric operation valve and so on. In addition to the components described above, hydraulic control systems require hydraulic auxiliary components. These components include pipes and fittings, fuel tanks, filters, accumulators and seals. Through the above devices, we can build a hydraulic circuit. The so-called hydraulic circuit is the corresponding control circuit formed by various hydraulic devices. According to different control objectives, we can design different circuits, such as pressure control circuit, speed control circuit, multi-cylinder work control circuit, etc. According to the structure and characteristics of the hydraulic transmission, in the design of the hydraulic system, a system analysis is first performed, and then a schematic diagram of the system is drawn up, in which the schematic diagram is represented by a hydraulic mechanical symbol. Then, the hydraulic components are selected through calculation, and then the system design and debugging are completed. In this process, the drawing of the schematic is the most critical. It determines the pros and cons of a design system. The application of hydraulic transmission is very strong. For example, the hydraulic system of the loading and unloading stacker is used as a storage machine in modern warehouses to realize the mechanization of loading and unloading of goods such as textile bags, oil drums, and wooden barrels. It can also be applied in the production practice of universal cylindrical grinder hydraulic system. These systems are characterized by relatively high power, high production efficiency and good stability.
    After continuous development, the application of hydraulic or pneumatic is particularly prominent in the following two aspects: military industry: today's military weapons, aircraft, tanks, warships, aircraft carriers, etc., the use of hydraulic and pneumatic technology can be seen everywhere, for example, aircraft carriers Aircraft landing platform. If the fighter aircraft is simply docked on the aircraft carrier deck, it is unsafe, and it is easy to be attacked by the enemy. In that case, the fighter aircraft on the entire deck will become cannon fodder. Without the fighter aircraft carrier fleet, it is equivalent to losing more than half The combat effectiveness will have a great impact on the war. On the contrary, after the aircraft carrier has installed the lifting platform, the fighter aircraft landing on the deck can be transported to the hangar below the deck through the aircraft lifting platform if there is no new combat mission. It avoids the danger of being attacked by air attacks, and saves a large part of the space on the deck, which is conducive to the safe take-off and landing of other fighters. Another example is a missile tank. A huge missile combat vehicle with a total weight of more than 30 tons. It is impossible to complete the operation by pulling the shoulders of people in the past. After using hydraulic and pneumatic technology, dozens of tons of missiles can pass the launch vehicle. The automatic control system lifts the projectile through a large hydraulic rod and accurately arranges the firing angle. The entire process requires only three people, which is very efficient. In addition, artillery controls for military industries, ship stabilizers, aircraft simulations, retractable devices for aircraft landing gear, and rudder control devices are real applications of hydro-pneumatic technology. Hydraulic applications are as small as general industrial plastic processing machinery, pressure machinery, machine tools, etc .; construction machinery, construction machinery, agricultural machinery, automobiles, etc. in mobile machinery; metallurgical machinery, lifting equipment, roll adjustment equipment, etc. for the steel industry ; Flood control gates and dam devices, river bed lifting devices, bridge control mechanisms, etc. for civil and water conservancy projects; power plant turbine speed governing devices, nuclear power plants and other countries; ship deck cranes, bow doors, bulkhead valves, stern Thrusters, etc .; giant antenna control devices for special technologies, measuring buoys, lifting and rotating stages, etc. Hydraulic and pneumatic technology is much more widely used in the civilian industry than in the military industry. The current industry has developed into a rather large industrial system, which can be divided into several major sectors such as manufacturing, construction, and service industries. Hydraulic and pneumatic technologies are more commonly used in manufacturing and construction, especially large-scale industries. In the equipment manufacturing industry, the role of pneumatic hydraulics is very important. For example, excavators, bulldozers, and forklifts that we often see, all transmit power through hydraulic rods, thereby instructing the movement of various components and ultimately achieving the purpose of work. In the construction industry, large rail-mounted construction machinery can transport materials weighing hundreds of tons to thousands of tons to a specified location and complete work, such as the construction of high-speed rail viaducts, where most of the bridge components are poured in one place. Cast, and then transported to the bridge for installation by a transport vehicle, the entire process requires a relatively powerful hydraulic combination machinery to complete. As a widely used technology, pneumatic hydraulic technology has a bright future in the future. With the acceleration of the pace of socialist construction in China, the rapid development of infrastructure construction in transportation, energy, railways, and civil aviation in China, the scale of large-scale construction and resource development has continued to expand, and the demand for construction machinery in the market has greatly increased. The dependence on pneumatic and hydraulic pressure will become stronger and stronger, and the requirements brought by these large-scale projects are more severe, and the working conditions will be more complicated. In-depth research on pneumatic and hydraulic transmission technology. With the in-depth development of computer technology, hydraulic control systems can be combined with technologies such as intelligent control technology and computer-controlled technology, so that they can play a role in more occasions. With more sophisticated and flexible to complete the expected control tasks. Pneumatic and hydraulic transmission technology has changed human life in various aspects, but it still cannot meet people's requirements. There is still a lot of room for development of pneumatic and hydraulic transmission technology. China's level in this area is not very high, so we need to invest more More power to catch up with the world level as soon as possible and accumulate a certain level of industrial technology to meet the rapid development of society. The prospect of hydraulic technology is broad, and we expect great breakthroughs in this technology. ...
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