Overview of gear pump development in China
Overview of gear pump development in China
In all kinds of hydraulic gear pump, hydraulic gear pump has simple structure, compact, and the advantages of small volume, light weight, good self-priming performance, is not sensitive to pollution, reliable operation, long service life, easy maintenance, low cost, and because the gear is symmetrical body of revolution, it allows high speed rotation etc., are widely used in machine tool industry, agricultural machinery, shipbuilding, aviation engineering.
The mark of the development of gear pump is the improvement of pressure grade, the early gear pump is either axial (gear end direction) or radial (gear circumference direction) is fixed clearance type, the pressure is less than 10MPa. In the past 30 years, after the efforts of hydraulic workers, such as the use of axial, radial clearance compensation method, the gear pump pressure class significantly increased, up to 31.5Mpa, has been crowded into the high-pressure industry, changed the past people think that gear pump is only used for low-pressure system. The main shortcomings of the gear pump is the pressure pulsation, leakage increase under high pressure, if can be overcome, that is, the gear pump not only maintain the advantages of easy manufacturing, low cost, and can replace some of the difficult manufacturing pump (such as plunger pump) to expand the use range, this will obviously bring greater technical value and social and economic benefits.
Many countries have made great breakthroughs in the technological research of gear pump in recent years. For the pump of ShimazuSeisakusho company in Japan, in order to make the oil suction chamber and oil pressure chamber of the pump have reliable seal, special groove is set in the end cover, and embedded with elastic seal strip, making the volume efficiency high. Czech developed pump, driven gear mounted on the ball support, to ensure self-centering with the driving wheel, and reduce noise. The pump of Saitama Ki Ki company in Japan has small variation of trapped oil volume, thus reducing pressure pulsation and improving working stability.
The development status of China's gear pump is: 1) the radial and axial clearance of low-pressure gear pump is fixed value, using the gap sealing principle, the BC pump of Shanghai machine tool factory and the cb-b pump of wuxi hydraulic parts factory belong to this kind of pump. 2) middle and high pressure pumps can be divided into two types according to the axial clearance automatic compensation. One is the floating shaft sleeve type, such as CB series of Yangtze river hydraulic parts factory and YBC series of shijiazhuang coal mine machinery factory; Another is the elastic side plate structure, such as yuci hydraulic parts factory CB-BF pump. 3) a typical high-pressure gear pump is cb-l type gear pump of changjiang hydraulic parts factory, which has an axial and radial clearance balance structure . CBZ2 series high pressure gear pump produced by jinan hydraulic parts factory USES axial compensation and radial tracking compensation to reduce the high pressure zone and radial force. Now it has applied for patent in China. CBZb series adopts axial and radial floating compensation of gear to reduce the inherent radial force of gear pump and achieve high pressure with the use of rolling bearings. Now it has applied for patents in China, the United States, Japan and other countries.
In recent years, with the continuous growth of gear pump output, in the gear pump to high pressure, high reliability development, China's gear pump technology has a new development and breakthrough. Gear pump is developing in the direction of high integration and modularization, pay attention to environmental protection, develop zero leakage and low noise components, threaded insert valve has been widely used, pump noise significantly reduced, hydraulic pump variable information, intelligent control has been widely used. Japan, Denmark, the United States and other countries have products for sale. Rapidly biodegradable fluids are used, such as benzene based oil and synthetic aliphatic based transmission media, to reduce pollution. Water hydraulic transmission has been widely paid attention to, Japan, Finland's science and technology workers have done a lot of work, Japan, Denmark, the United States and other countries have products for sale. Zhou hua and li zhuangyun of huazhong university of science and technology in China have made significant research on seawater hydraulic pump. Pure water hydraulic pump is one of the most important components in pure water hydraulic system. Pure water, as the medium of hydraulic pump system, is compatible with the environment, the system is simple and safe, fire resistant and energy saving, economy and health and other green features, meeting the needs of human sustainable development. Danfoss, a Danish company, is a typical supplier of hydraulic water pump components, with its Nessie series of hydraulic water components already on the market. Hanhinc Gmbh of Germany and Fenner of Britain also supply a series of hydraulic pump components. East China university of science and technology has achieved considerable development.
The CAD design changes the manual design formula into automatic and semi-automatic formula, especially the popularization and application of CAD/CAM/CAPP make the hydraulic technology develop rapidly. In recent ten years, workstations and PCS are widely popularized. In foreign countries, the application of hydraulic CAD plays a very important role in improving design quality, speeding up design speed and promoting the upgrading of hydraulic products. Ninety s hydraulic CAD technology rapid development, the development of hydraulic technology under a long-term goal is: to use CAD technology to fully support hydraulic products from concept design, appearance design, performance design, reliability design to the components design process in detail, and the computer aided design (CAD), computer aided analysis (CAE), computer aided process planning (CAPP), computer aided testing (CAI), computer aided test (CAT) and modern management system integration in together, set up computer manufacturing system, the hydraulic design and manufacturing technology have a breakthrough.
Throughout the development of gear pump, we can see: from the perspective of the leakage compensation technology of gear pump, the development of external gear pump experienced: no compensation → axial compensation → axial and radial compensation process at the same time. From the measures to reduce the radial force, the development of the gear pump experienced: expand the high pressure area → expand the low pressure area, and use the radial floating compensation force to reach the process of force balance, thus greatly improve the gear pump stress, significantly improve the service life of the gear pump. From the development of pressure grade, the development of gear pump experienced a low pressure → high pressure → high pressure process.
Since the application of hydraulic technology, gear pump high pressure research has never been interrupted. But due to the pressure, the efficiency of the gear pump is reduced, internal leakage increase, which will directly affect the development of hydraulic technology and popularization, at the same time, because of the high pressure oil out from all possible leakage clearance, thereby causing loss to the power, oil temperature fever, and will cause a lot of vibration and noise, seriously affect the working stability and service life of the pump. Efficiency is the ratio of system output to input power, which is the main index to measure the energy utilization of the system at work. Therefore, from the perspective of energy conservation, it is of positive and far-reaching significance to study and analyze the efficiency of hydraulic system and improve the utilization rate of energy. The efficiency of hydraulic system includes volumetric efficiency and mechanical efficiency, and volumetric efficiency is mainly reflected in leakage. Therefore, it is necessary to analyze the mechanism, causes and control of leakage.