| Development of high-speed on-off valve began in the1980s. High-speed on-off valve can achieve high accuracy hydraulic control, and also has the advantages of small volume, simple structure, flexible control, high reliability, Strong ability of anti pollution and low price etc. In the hydraulic control system, high speed on-off valve plays a very important role, directly affects the performance of the whole system performance. At present, many domestic and foreign universities and research institutions has studied high-speed on-off valve, and made some certain achievements. However, the hydraulic high-speed on-off valve has the contradiction between the large flow and high frequency response, which cannot meet the requirements of high-power and high precision in the hydraulic system.In this paper, A rotary hydraulic high-speed on-off valve has been proposed, which has two part structure, including a valve core and the valve sleeve. The valve core is mainly composed of PWM segment and both ends of the outlet. PWM segment is mainly composed of6helical blades which is alternately connected and the6oil outlet holes, both ends of the outlet mainly consists of three turbine blades. The valve sleeve is mainly composed of an oil inlet hole, an oil outlet hole, the middle annular oil hole and the three diamond shaped nozzle. The switch valve without external power, the spiral vane and turbine blade on the valve core is impacted by fluid in the high-speed on-off valve, which resulting in required rotary power. When the spool rotation, the hydraulic oil will flow back to the tank or to load selectively, Thus we have the switching action, switch frequency is decided by the rotating frequency of the valve core, the switching action need not acceleration and deceleration reversing operation, which reducing energy greatly. By changing the relative axial position of the valve core and the valve sleeve, can adjust PWM duty ratio of the on-off valve. PWM duty ratio adjustment range is0to100%. Axial displacement control system is mainly composed of a cycloid metering pump valve, H bridge control circuit and single-chip microcomputer, through the cycloid metering pump the hydraulic oil from one end to the other, to change the axial displacement of the spool. Thus the PWM duty ratio will be controlled. Through the analysis of the operating principle of hydraulic high-speed on-off valve, we should have the structured modeling of valve,3D software named Pro/Engineer wildfire5is used in this modeling. In order to analyze the flow field inside the valve, fluid inside the valve should be obtained by PRO/E software. The fluid inside the valve can be obtained by the command of excision. In order to analysis of the flow field inside the valve, the CFD software named FLUENT has been used. The structure of the on-off valve is optimized by analyzing the results of the simulation. The on-off valve has high frequency response (86.7HZ). At the same time, the controlling hydraulic system based on the combination of the switch valve has been set, advanced modeling and simulation software AMEsim has been used for automatic modeling the on-off valve, and the dynamic performance of the valve are analyzed. The load displacement controlled by regulating the duty ratio. According to the simulation results, the switching valve has good performance, and the dynamical displacement error is small, steady displacement error also reached to the design goal. Lay the foundation for the study on the future. |
PDF Full Text Request