Theoretical And Experimental Study On Piezoelectric Pump With Active Valve

The application of piezoelectric pump in micro-electro-mechanical system is an important branch of piezoelectric drive technique. The performance of piezoelectric pump depends on not only the actuator of piezoelectric pump chamber, but also the working manner of the inlet and outlet valve. Therefore in recent years, the studies on the valve were growing up in the research field of piezoelectric pump. According to this, the research on the piezoelectric pump with active valve was being developed. It is a new development direction of the piezoelectric pump, although the development of piezoelectric pump with active valve was still in the basic steps internationally.Funded by National Science Foundation of China (No.50575093), this thesis focused on developing piezoelectric pump with active valve. The basic theory, structural design and experimental test were analyzed and carried out in this thesis.The main content of this dissertation is as bellows:1. Introduction of piezoelectric pump with active valveBased on the research and analysis on the current research work on micro pump and micro valve, this paper focused mainly on the current condition and development of piezoelectric pump with active valve. The principal achievements of the study on piezoelectric pump are piezoelectric pump with check valve, piezoelectric stack pump, piezoelectric pump without check valve and piezoelectric ultrasonic pump and they are already widely used in biological gene, chemical analysis, and aero and space areas. The piezoelectric pump with active valve was a new concept which was brought forward in recent years. The main achievements are only piezoelectric membrane, peristalsis and piezoelectric stack drive piezoelectric pump with active valve. Hence, understanding the working condition deeply and improving the performance of piezoelectric pump with active valve are new emphasis of the study on piezoelectric pump.2. Analysis on the piezoelectric actuator used to generate pump chamber volume differenceAccording to the characteristics of piezoelectric actuator and working condition of pump, the piezoelectric actuator used as prime mover of piezoelectric pump is selected. By theoretical and FEM analysis, the structural parameters of piezoelectric actuator were optimized; by experimental test, the static and dynamic characteristics of piezoelectric actuator were measured and analyzed; the experimental results testified the validity of FEM model of piezoelectric actuator; through the results of analysis, the radial deflection of piezoelectric actuator was obtained, which provides the theoretical references to the design of piezoelectric pump and active valve driven by piezoelectric actuator.3. Research on the characteristic of active valve driven by piezoelectric actuatorBased on the specifications of different kinds of piezoelectric actuator, the ones proper to be the actuators of active valve are selected. The first active valve is driven by circular piezoelectric bimorph actuator. By calculating the theoretical flow, the diameters and width of the valve are known as the factors influencing the flow; the relations between the valve inside diameter, deflection of circular piezoelectric vibrator and flow area were analyzed. Also, the valve based on rectangular piezoelectric bimorph actuator was designed. The structural parameters of the rectangular piezoelectric bimorph actuator are optimized by FEM first and its performance was simulated meanwhile; the static and dynamic characteristics of rectangular piezoelectric bimorph actuator were measured and analyzed through experimental test; the factors which have influences on the flow are analyzed. Finally, two types of active valve are tested.4. Design theory of piezoelectric pumpAccording to the working principle of single chamber piezoelectric pump with valve, the influence of structural parameters of pump chamber on the performance of piezoelectric pump and the pressure distribution inside the chamber are analyzed; Together with analysis on the characteristics of circular piezoelectric vibrator, the theoretical output flow of piezoelectric pump are calculated and tested. All things above supply the theoretical references to the design of piezoelectric pump.5. Set-up of experimental test rig of piezoelectric pump with active valveAccording to the requirements of piezoelectric pump on the drive signal, the test rig based on LABVIEW was built up. The rig has the functions of two channels output, signal type can be selected, adjustable amplitude, frequency, duty cycly and phase.6. Design of piezoelectric pump with active valveBased on the two types of active valves designed previously, the piezoelectric pumps together with the active valves are manufactured. The performance of two types of piezoelectric pump with active valve are measured and compared. The factors which affect the performance of pump, such as back pressure, voltage, frequency, phase, and duty cycle, are analyzed.