Theoretical And Experimental Research On The Compressor Of Hundred Hertz Miniaturization Pulse Tube Cryocooler

Cryocoolers have important application value in the space,military and other fields due to low vibration,high reliability,long MTBF(mean time before failure),etc.The scaling down of size and weight of Stirling cryocooler and Stirling type pulse tube cryocooler is one of the major developments,which is of great value in conserving the space resource of the spacecraft.Being the pressure wave generator of the cryocooler,the size of the linear compressor determines the size of the overall cryocooler.The Miniaturization of the linear compressor is of great significance on the miniaturization of the whole machine.The research on the performance of the linear motor is crucial to the performance of the linear compressor.In this paper,the two-dimensional model of the linear motor is taken as the main object,through the finite element analysis method,the detailed analysis and research and experimental verification are carried out.The following work is included.In this paper,the main types and development history of linear compressor are introduced,the characteristics,advantages and disadvantages of the moving coil and moving magnet and the reasons of formation are pointed out.The design and optimization of the dynamic system parameters are carried out with the aim of the resonant state of the whole machine.The main theories and research ideas of the miniaturization of cryocooler are introduced,including the principle of miniaturization of the regenerator,the linear scaling rule of the cryocooler.In the study of the magnetic circuit of the motor,the influence of the parameters such as the material performance and the structure size on the motor performance are studied and analyzed by means of the finite element analysis method based on the magnetic circuit analysis method.In the moving magnet motor,when the number of coil turns is less than 410 turns,the motor power consumption increases,the power factor decreases,and the motor efficiency increases as the number of turns increases.While the coil axis length increases,the power factor and motor efficiency increase.When the thickness of the inner yoke increases within 4mm,the effect of motor performance optimization is very obvious.After the thickness of the outer yoke exceeds 1mm,the effect of increasing the thickness on the motor performance is no longer significant,and the increase of the motor air gap height will lead to lower power factor.Increasing the outer yoke corner thickness has no obvious influence on the motor performance,but will alleviate the magnetic saturation phenomenon.The causes and solutions of the magnetic spring effect of the magnetic motor are explained.Through the verification of the experimental prototype,the compressor can meet the performance requirement well under the certain refrigeration condition.When the compressor is matched with the cold finger of the 120 Hz high frequency pulse tube cryocooler,the cooling capacity is 1W @ 80 K at the input power of 34 W,the power factor is 0.87,the motor efficiency is 84.1%.When the compressor is matched with the 120 Hz pneumatic Stirling cold finger,the cooling capacity is 1W @ 80 K at the input power of 34 W,the power factor is 0.72,and the compressor efficiency is 84.7%.The core loss experiment is carried out to clarify the motor power distribution,and the test method is proved to be quite accurate.On the basis of the current compressor,the cryocooler is further miniaturized by reducing the outer diameter of the motor.By combining with the cold finger design,it is possible to reduce the size of the cryocooler with relative high efficiency.