Linear Compressor Research

A traditional reciprocating compressor with a rotary motor which used in a refrigerator or air-conditioner is of low efficiency since it has the large mechanical losses due to the crank-guide mechanism. Another weakness of the compressor is its difficulty to fulfill oil-less lubrication, which causes many new harmless refrigerants can not be used. Now a linear compressor with a common supposition can overcome above shortcomings, which has a smaller radial force on its piston and without crank mechanism. Furthermore, capacity modulation can be easily performed since its piston moves freely.In the thesis, a coil-moving type linear compressor is studied. The mathematical models about mechanical and electromagnetic systems of it are established. Because the gas force in the models has nonlinear characteristics, and moreover the mechanical part is coupled with the electromagnetic part, dynamics analysis of the whole system is very complicated. Hence, the describing function approach is employed to linearize the models, by which the equivalent stiffness and damping of the system are obtained and static and dynamic components of the gas force decoupled. For proving of the accuracy of the linearized model, a computing program is coded to emulate the nonlinear model and some results from the two models are compared. In the following, a few main characteristics of this kind of compressor are analyzed. Results of which indicate merits mentioned above, and the moving of the piston is stable with a strong ability of anti-interference, and so on. Finally, a detailed designing way of the mechanical and electromagnetic systems and optimizations of major parameters are presented.