【正文】 Programmable Logic Controller (PLC) is an industrial control puter, is the succession of puter, automatic control technology and munication technology as one of the new automatic device. It has strong antiinterference ability, low price, reliability, programming is simple, easy to use and so on, in the industrial field operators by the likes of engineering, so PLC in all areas of industrial control is widely used. The design is based on the ratio of the hydraulic cylinder piston rod valve position control system, namely the use of PLC control signal generated by electrohydraulic proportional valve driver to control the exact location of the hydraulic cylinder. Hydraulic cylinder piston rod displacement sensor displacement feedback signal output by the A / D converted into digital signals into the puter, the PLC signals within a given parison, and the control algorithm according to the set after the output control signal, after D / A converted to analog voltage or current signal proportional electrohydraulic control valve spool position to control the flow of the hydraulic cylinder transmission, drive hydraulic cylinder, to achieve the position of the piston with a load control system as a whole constitute a closedloop control for precise positioning . 原 文 摘 要 液壓升降平臺(tái)是一種多功能起重升降設(shè)備，廣泛應(yīng)用于工廠、碼頭、建筑、交通、體育館、設(shè)備檢修等高空作業(yè)及維修。s rapid economic development, in order to adapt to China in various fields used by the synchronous hydraulic lifting platform development needs and take the largescale, standardized , intensive, product support services, achieving mechanical, electrical, fluid integration platform in the application of synchronous movements. The use of synchronous hydraulic lifting platform surface, the service has been expanding, is now in rapid development stage, and now hydraulic lifting platform reliability, security, easy operation and simple directness, and other aspects greatly improved, and with the the popularity and development of puter and mechanical, electrical, fluid integration progress of the study, major domestic and foreign panies have to pete with the puter (electronic) control system to improve overall performance and reduce the use of hydraulic ponents, machine, reducing the whole size and weight, improve the sensitivity of control and synchronization accuracy. In particular, the manufacturers actively introducing and digesting foreign advanced technology, development of new varieties, improving product technology and quality level, has been part of the hydraulic lifting platform synchronized at or close to the international level of similar products. Currently used in the automotive repair Hydraulic synchronous lift platform vehicle maintenance plays an important role in synchronous lifting platform on a variety of hydraulic valves, hydraulic cylinders, hydraulic pump station innovation and improvement, making a hydraulic lifting platform synchronization Smooth running, low noise, fast response, high precision synchronization, for the repair and maintenance of the car plays an irreplaceable role in a wide range prospects. Therefore, the lifting platform for further research and improvement, optimize system performance and structure to further improve to make up for the shortings of existing technology has important significance. The subject of the design of the hydraulic lifting platform main use of theoretical research and design, through the understanding and study of the hydraulic system, as well as existing control technologies and more indepth research and development, in the hydraulic system ponents and further understanding and learning , Combined with the modernization of hydraulic ponents and automation and control ponents within the hydraulic control through traditional hightech ponents and control elements of existing parative and prehensive application of the traditional hydraulic system, based on the research and design more innovative set of machines , Electricity, liquid in one of the hydraulic control system, makes the system more stable and faster to achieve the advantages. Hydraulic lift platform system, requires the ability to achieve fourwheeled vehicles in a controlled synchronous lifting height lifting range, to achieve safe and reliable control of the two front, two rear, two revolvers, two rounds of synchronous lifting the right and to ensure synchronous movements accuracy. The hydraulic lift system also must have a fast response speed, hydraulic power units, small size, pact structure, large power weight ratio, ease of manipulation and control, laborsaving convenience and easy to implement automated, with overload protection for high reliability requirements system, excellent technical performance, while ensuring synchronous hydraulic lifting platform can be anywhere in the vertical direction on a longer time (60 min or longer) within a reliable locking, the system can work continuously and reliably, the system energy efficient, easy to maintain low cost. Hydraulic lift platform to meet system design requirements, synchronous movements smooth