Research On The Key Technologies Of Pneumatic High-Speed On/Off Vavle

With advantages of low cost, anti-pollution ability, high flow rate gain, small size and simple structure, electro-pneumatic high-speed on/off valves have attracted considerable attention in several areas of modern industry. They have been used in sorting parts, flapping control systems and other systems for gluing, dosing and packaging where discrete cyclic, linear or rotating motions and a very long lifetime are required, and have come to a hot topic of research on the pneumatic technology. Besides, with the development of integrated circuits, they have been used to substite the expensive pneumatic proportional or sevro valve for precise and fine position, force or positon control by adopting pulse witdth modulation technology. Research on the key technology of electro-pneumatic high-speed on/off valve would help to better meet the ever-increasing needs of market and to promote development in the field of pneumatic components of China.Based on theory analysis, mathematical modeling, numerical simulation and experimental study, the pneumatic high speed on/off valves are systematically, deeply researched in the thesis. With magnetic circuit analysis and finite element simulation, the influences of the structural and control parameters on the vavle performance are analyzed in detail. A new s-type solenoid is presented for improving the dynamic characteristics of high speed on/off valve based on traditional E-type solenoid. Simulation and test results indicate thatε-type solenoid considerably reduces the armature weight that the actuator's response times are decreased by typically 10% under different work conditions with the same level magnetic force. The on/off valve based on this solenoid has a typical on/off time of 0.8ms and 0.8ms, and a maximum volume flow rate of 70L/min under source pressure of 5Bar. A C-type solenoid with a tiny size of 24mm*12mm*3mm is present to meet the compact requiremens from industry automation. It has a typical magnetic force of 20～30N, and the on/off valve based on it has a typical on/off time of 0.8ms and 0.8ms, and a volume flow rate of 45L/min under source pressure of 5Bar. As an application example of the high speed on/off valve, a simplified optical sorting device is successfully developed for sorting particles with different color automatically. The main content of each chapter is summarized as following:In chapter 1, the research progress of high speed solenoids for electro-hydraulic or electro-pneumatic on/off vavles are introduced, and the structural features, working status, application requirements and development trend of pneumatic on/off valves are summarized. Relative technologies such as the valve driving circuits, the pneumatic servo control by using on/off valves, the optical sorting system and the magnetic material are also presented.In chapter 2, from standpoints of the static mass flow rate, the dynamic response characteristics, the temperature performance, and the stability and life performance for pneumatic high speed on/off valves, the design method and acquirements for the valve are summarized. The influences of the magnetic material on the valve static and dynamic characteristics are illustrated in detailly as the design basis, and two on/off valves based on the traditional E-type and C-type solenoids are presented finally.In chapter 3, the magneti circuit models of two high speed solenoids for electro-pneumatic valves are established, fringe flux, leakage flux, and magnetic saturation are took into account in the model. Formulas for deciding the solenoid force are derived and presented explicitly, and then the primitive structrual parameters for two solenoids are presented as the design basis. Finite element models (FEM) of the solenoids are also established, comparisons between the simulation results from the FEM and magnetic circuit model are presented. The action mechanism of the structural parameters on solenoids are analyzed in detail with FEM, and then the specific solenoid structural parameters are determined. A newε-type solenoid is developed based on the traditional E-type solenoid, and a compacted C-type solenoid is also presented to meet the requirement from industrial application.In chapter 4, two numerical analysis models for the dynamic characteristics of on/off valves are presented, one is based on the flux variation in the magnetic ciruit, while the other one is based on hybrid FEM-LPM (Lumped Parameter Model) mode. Comparisons between different simulation methods are presented firstly, and then from standpoints of the simulation efficiency and accuracy, FEM is adopted for the dynamic performance of the E-type solenoid, while the hybrid FEM-LPM method is adopted for the C-type solenoid. Influences of different factors on the on/off valve dynamic properties are simulated, some conlusions are presented for the improvment of dynamic performance of on/off valves.In chapter 5, a series of test rigs for electro-pneumatic high speed on/off valves, such as force-stroke characteristics, armature dynamic stroke, step pressure reponse of the valve command chamber, coil current, valve mass flow rate and the solenoid temperature, are introduced. Based on these systems, the static and dynamic characteristics of two solenoids are measured, and compared with the simulation results. A simplified optical sorting system are developed based on the newly designed valves, particles with different color, such as yellow and white, can be sorted automatically with this system.In chapter 6, all achievements of the dissertation are summarized and the further research work is put forward.