| The development of micropump technology promotes the integration of micropump in microfluidic equipment,thus meeting the requirements of precise fluid delivery.Piezoelectric pump is a driving element in the field of microfluidics.Because of its small size,high speed and strong portability,it is widely used in chemical analysis,drug delivery,biological analysis and other microfluidics.As a branch of piezoelectric pump,passive valve piezoelectric pump has higher output performance compared with valveless piezoelectric pump and simpler structure compared with active valve piezoelectric pump.The traditional straight arm wheel valve adopts the installation method of gluing or hot welding,which will shorten the service life of piezoelectric pump.Moreover,the material is mostly silicon,and the valve body has high opening pressure and low response speed.In order to reduce the errors caused by manual assembly,improve the service life of piezoelectric,and improve the opening and response speed of the valve,this paper selects silica gel as the valve manufacturing material,designs a special valve seat to install the valve body,puts forward a passive valve piezoelectric pump with high output flow and high output pressure,and analyzes and verifies its thermal management ability,which provides a reference for the application field of passive valve piezoelectric pump in computer chip cooling.The main research contents of this paper are as follows:(1)The PZT5 piezoelectric ceramic is selected as the driving source,and the circular copper substrate is compounded to increase the driving effect of the driver.According to the selected driver,the diameter of the cavity and the overall size of the valve are determined,and then the inlet and outlet positions of the pump body are determined.Based on the configuration of piezoelectric vibrator and the structural characteristics of straight arm wheel valve,the layered assembly structure is selected,which paves the way for the subsequent experimental work.(2)The mechanical model of the valve is established,and the opening of the straight-arm wheeled valve is analyzed theoretically,and the influence of various structural parameters of the straight-arm wheeled valve on the opening of the valve body is analyzed.The derivation formulas of the output flow and pressure of the piezoelectric pump with the straight-arm wheeled valve are obtained theoretically,which provides a reference for the design of the piezoelectric pump with the straight-arm wheeled valve.The influencing factors of the thermal management ability of the piezoelectric pump with straight arm wheel valve are analyzed,which provides a theoretical basis for the subsequent experimental work.(3)The stress and strain of the straight arm wheeled valve are simulated and analyzed by CFX fluid module in ANSYS simulation software,and the structural characteristics of the straight arm wheeled valve with different valve arms are obtained.Through Icepak thermal simulation module in ANSYS simulation software,the internal flow field distribution and external temperature distribution of the heat dissipation block at different flow rates were simulated and analyzed.(4)According to the design points of the piezoelectric pump with straight arm wheel valve,the experimental research parameters are selected: the number of valve arms(2,3,4,5),the length of valve arms(1.92 mm,2.02 mm,2.12mm),the width of valve arms(0.8mm,1.0mm,1.2mm)and the thickness of valve(0.6 mm,1.0 mm).A testing platform for the piezoelectric pump with straight arm wheel valve was built.Based on the single-chamber piezoelectric pump,the parameter characteristics of the straight arm wheel valve were obtained by experimental test,and its opening pressure,output flow rate and output pressure were measured.The thermal management ability and noise characteristics were evaluated.The experimental results show that when the number of valve arms is 2,the length of valve arms is 2.02 mm,the width of valve arms is 1mm and the thickness of valve is 0.6mm,the output flow rate of single-chamber piezoelectric pump reaches 431.6m L/min.When the number of valve arms is 4,the width of valve arms is 1mm,and the thickness of valve arms is 1mm,the output pressure of single-chamber piezoelectric pump is 27.41 KPa.With the piezoelectric pump with the best flow rate as the driving unit,when the flow rate is 120 m L/min,the computer CPU temperature drops by 2℃,which provides a reference for the future application of the piezoelectric pump with straight arm wheel valve in the thermal management of electronic components. |
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