Research On Pneumatic High-speed Switching Valve Based On Piezoelectric Bimorp

Using new materials to replace the solenoid structure to study the valve core driving device has become an important research direction of high-speed on-off valve,and piezoelectric ceramics is one of them.At present,most of the research of piezoelectric valve is based on piezoelectric stack.It is necessary to set up micro displacement amplification device to obtain large flow,which makes the valve structure large and the requirements of installation and manufacturing accuracy high.Due to the large displacement of piezoelectric bimorph,there is no such problem,but the small output force of traditional cantilever structure makes it unable to meet the application of medium flow valve structure.To solve this problem,the following work is carried out in this paper.Firstly,the piezoelectric bimorph and piezoelectric ceramic driving power supply are selected,based on the analysis of the working principle and basic characteristics of piezoelectric bimorph.The output displacement and output characteristics of the selected piezoelectric bimorph in the installation and fixation mode of simply supported beam structure are theoretically analyzed,and the effectiveness of the theoretical model is verified by simulation.On this basis,the through-hole radius at the valve core of the high-speed on-off valve is selected and analyzed,and the overall structure design of the valve is completed.Then,the piezoelectric current solid triple coupling between piezoelectric bimorph and gas is simulated,and the actual gas force at the spool of piezoelectric valve under coupling working state is clarified,with the help of COMSOL multi-physical field finite element simulation software.On this basis,the dynamic simulation model of the piezoelectric highspeed on-off valve is built with the help of MATLAB/Simulink.Considering the influence of hysteresis characteristics of piezoelectric ceramics on spool displacement,the hysteresis nonlinearity of piezoelectric bimorph is modeled by the-hysteresis model.Taking the flow as the objective function,the optimization design of two key structural parameters,including the fulcrum position and the inlet radius,is completed based on a genetic algorithm.Finally,according to the actual needs of the performance measurement of the developed piezoelectric high-speed on-off valve,the software and hardware platform of the test system is built,and the dynamic and static characteristics of the valve are experimentally studied.The experimental results show that: the opening response time of the valve core is 2.4ms and the closing response time is 1.8ms;Compared with the cantilever structure,the working bandwidth of the piezoelectric bimorph installed in the fixed mode of the designed simply supported beam structure is significantly improved,which can reach about 280 Hz,while the cantilever structure is only 60Hz;The air tightness of the valve is good,and there is no visible leakage within 1min test time under the pressure difference of 0.3MPa;The voltage-flow characteristics of the valve have obvious hysteresis,while the duty cycle flow characteristics of the valve have better proportional flow characteristics;Under the rated working difference of 0.3MPa,the maximum flow of the valve can reach 30.7L/min.