Dynamic Development Of The Magnetic Line Of Air Compressors

The aim of the paper is to design and develop a micro, portable, efficient linear air compressor based on the research of the internal mechanisms of Moving-Magnet type linear compressor. Compared with conventional micro piston compressors driven by rotary motor, linear compressor is a new model without crank and connecting rod for the piston is driven by a linear motor, so it allows oil-free lubrication. Capacity continuous modulation by adjusting of the voltage amplitude enables efficient operation throughout nearly all of its operation range.This thesis focuses on a Moving-Magnet type linear compressor, in which magnetic field is generated by a coil and a permanent magnet. Equivalent magnetic circuit model was built for the Moving-Magnet type linear compressor and the formula for calculating the electromagnetic force and the system voltage equation was obtained. Then the mathematical model of the system was established, and simplified the nonlinear gas force to the equivalent gas stiffness and damping. Then we got the result of the differential equations using Runge-Kutta Method; A magnetism and solid coupling dynamic analysis model was established by finite element method for the model of Moving-Magnet type linear compressor. In this model, the influence of the nonlinearity of magnetic circuit, leak magnetic flux and the position of the magnet was considered. So it is more integrity than the model of equivalent magnetic circuit. Some analysis results were provided in this article, indicating the relationship among the electromagnetic force, displacement of permanent magnet and current. Besides, some magnetic flux density drawings of different voltage and different time were given too, there indicating the distributing characteristics of the electromagnetism field and saturation characteristics of magnetic route. These anslysis lays the foundation for optimized design of linear compressor.The main capability of linear compressor is determined by dynamic response. The result of the equivalent magnetic circuit model and the finite element model were used to research the factors, such as the location of the coil, the diameter of wire, the diameter and displacement of piston, which affect the dynamic response, and then the capability of compressor was boosted. An effective design of support of piston, spring design and magnet were created and a Moving-Magnet linear compressor was developed.A testing system was established in this thesis. The no load experiment and load experiment are introduced also, parameters such as displacement, frequency, current, voltage, power and the correlative relation were obtained from the research of characteristic of the sample. The various losses and specific thrust in the linear compressor were obtained by the experiment method. The mechanical resonant frequency was tested when the piston was with load or without. The linear compressor's performance parameters were presented when the backpressure was 0.7MPa. In the end, the effects on the linear compressor's performance were discussed.