| With the continuous development of manned spaceflight,lunar exploration engineering and deep space exploration technology,higher requirements are placed on the small size and low power consumption of experimental instruments in the mission.A small-sized vacuum pump is one of the key components for instruments such as biochemical analysis instruments(typically mass spectrometers)or electronic components(typically such as traveling wave tubes).Due to the size limitation of current micro vacuum pumps,the size of micro-analytical systems or electronic components is difficult to further shrink,which limits the further application of micro-analytical instruments in aerospace,military exploration and militarycivilian integration.In order to break through the vacuum pump size,this paper designs a micro-scale volumetric vacuum pump that can be applied to portable gas analysis systems.Its structure is relatively simple,low power consumption,miniature size and can achieve reasonable vacuum requirements.In this design,the piezoelectric drive is integrated in the vacuum pump,and the combined actuation of the pump chamber and the active valve is achieved by the piezoelectric drive under the action of the control signal.The ultimate stress of the diaphragm-plunger and the maximum shape variable of the diaphragm can be analyzed by nonlinear stress modeling.The inlet and outlet pressure difference and flow rate that the pump can obtain during the working process are analyzed by fluid flow modeling.At the same time,the gas flow resistance of the vacuum pump during pumping/exhausting and the time response in six different stages were analyzed by the method of lumped parameter element modeling.In the design of the chip structure of each layer of the vacuum pump,static analysis of the size of the diaphragm-plunger structure of the three sets of parameters,a total of 27 combinations,and based on the layout of the vacuum pump multi-stage chip,the valve-pump cavity The valve was analyzed by fluid dynamics using the structural layout of 120°.On the basis of the completed analysis and comparison,the dynamic analysis of the diaphragm of the optimal structure is carried out,and the mode shape and frequency of the first six-order vibration are obtained.In the design of the driver layer chip,under different applied voltages(20～60 V),the structural parameters of different piezoelectric sheets are compared and analyzed,and the maximum shape variable that can be realized by the applied voltage of the piezoelectric sheet is obtained.Through the analysis and comparison of the parameters of the vacuum pump fluid channel layer chip structure and the design of the multi-stage pump scheme,the optimal structure(120°arrangement)and the optimal parameter combination in the design of the MEMS vacuum pump are obtained:the diaphragm diameter φ=6mm,the ring The width of the region is d=500μm,and the thickness of the diaphragm is h=10μm.The flow of the gas in the vacuum pump is analyzed by the method of fluid-solid coupling.When the vibration frequency of the diaphragm-plunger is f=5Hz,the pressure difference that can be achieved by the vacuum pump is Δ P=440.6Pa,the flow rate is Q=3.14sccm;the response time analysis is carried out for the six stages in the working process of the vacuum pump,and the main time response is obtained:τpre-pumping=20.83ms,τpumping=220.76ms,τpre-exhausting=3.86ms,τexhausting=78.40ms.The above analysis provides important theoretical support for the processing and manufacturing of vacuum pumps and further in-depth research. |
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