| As an important component of microfluidic systems,piezoelectric pumps have a wide range of applications in biomedicine,chemical engineering and microelectronic device cooling due to their simple structure,ease of manufacture,low cost,small size and controllable output performance.For example,a piezoelectric pump for insulin injection requires a small flow rate,high accuracy,while a piezoelectric pump for computer water cooling requires a larger output flow rate and output pressure.It is therefore of great interest to investigate a high flow piezoelectric pump simple,inexpensive and can produce a high output pressure.There are three main ways to improve the performance of piezoelectric pumps:firstly,by replacing the piezoelectric oscillator with a larger size;secondly,by increasing the amplitude at the center of the piezoelectric oscillator thanks to a displacement amplification mechanism;thirdly,by increasing the number of piezoelectric oscillators and,as the number of pump chambers increases,different multi-chamber structures can derive.Currently three main types of coupling for multichamber piezoelectric pumps,namely series,parallel and hybrid.With the increase in the number of piezoelectric oscillators,the output flow and output pressure can be effectively increased,but it also makes the overall volume of the piezoelectric pump larger.Therefore,this paper proposes a "cascade" distribution of pump chambers based on series and parallel structures to achieve high flow and high-pressure output performance of piezoelectric pumps.The research content is as follows.1.Combining piezoelectric theory and vibration mechanics,the vibration process of the piezoelectric oscillator is theoretically analyzed,and the vibration mode and support method of the piezoelectric oscillator are discussed.A piezoelectric oscillator with a brass substrate diameter of 20 mm and a piezoelectric ceramic diameter of 14 mm is selected and a check valve and pump body are designed based on the piezoelectric oscillator dimensions.2.Combined with the simulation software Ansys,the piezoelectric oscillator and the cantilever beam valve are simulated and analyzed to obtain their vibration patterns at different resonant frequencies and to select a suitable operating frequency range.The amplitude of the piezoelectric oscillator is measured by a laser displacement sensor and the results are used as a reference for the design of the pump body dimensions.3.Prototype single-chamber piezoelectric pumps are fabricated and assembled,and the height of the pump chamber and the support width of the piezoelectric pump are experimentally compared using the controlled variable method to obtain the best structural parameters for performance.Combine the obtained parameters to design and build a two-chamber tandem piezoelectric pump,a four-chamber tandem piezoelectric pump and an eight-chamber parallel piezoelectric pump consisting of two four-chamber tandem piezoelectric pumps in parallel,test their output flow and output pressure,and then obtain the influence of the series and parallel structure on the performance of the piezoelectric pump.4.Experimental testing of piezoelectric pump output performance.The maximum output flow rate of the single-chamber piezoelectric pump is 36 m L/min at an effective sine voltage of 170 V and an operating frequency of 210Hz;the maximum output flow rate of the two-chamber series-connected piezoelectric pump is 49 m L/min and the maximum output pressure is 35 k Pa at an effective sine voltage of 170 V and an operating frequency of 120Hz;the maximum output pressure of the two-chamber series-connected piezoelectric pump is 35 k Pa at an effective sine voltage of 170 V and an operating frequency of 400 Hz.The maximum output flow rate of the four-chamber series piezoelectric pump is 114 m L/min and the maximum output pressure is 145 k Pa at an operating frequency of 400 Hz with a sinusoidal voltage of 170 V.The maximum output flow rate of the eight-chamber parallel piezoelectric pump is 210 m L/min for asynchronous drive and 211 m L/min for synchronous drive at an operating frequency of400 Hz.From the experimental data,it can be concluded that in a multi-chamber piezoelectric pump,a series connection can significantly increase the output pressure,a parallel connection can significantly increase the flow rate,and a combination of the two can have both output pressure and output flow rate.Using the structure proposed in this paper,as well as the series and parallel construction methods,high performance piezoelectric pumps can be produced,laying the foundation for future development of even higher performance piezoelectric pumps. |
