| The moving-magnet linear compressor is a new type of compressor based on the electromagnet oscillation theory, using the linear motor as driving source and the plate springs as mechanical transfer to transmit the reciprocating linear motion of the permanent magnet in the air gap to the piston in the cylinder, and thus to fulfill the compression of working gas. The advantages of no presence of crank connection rod allow it compacter in structure, easier to be under control, lower in noise and higher in efficiency. It has been used in various application fields, for instance, used as a compressor in traditional refrigeration system, oscillation drivers in all kinds of regenerative cryogenic systems or other compression and driving of fluid. It is promising to apply widely to variety of industrial fields.Aiming at the moving-magnet linear compressor, the following main contents are investigated in this thesis:1. Based on the forced damping oscillation model of moving-magnet linear compressor, the forces acted upon the compressor have been analyzed. The method of equivalent magnetic circuit and magnetic co-energy has been used to derive the expression for the motor electromagnetic force of moving-magnet linear motor. Then, finite element method has been applied to analyze the effects of the air-gap height, the radius and the thickness of permanent magnet on the motor electromagnetic force. Meanwhile, by the comparison of the simulated results by definite element with the calculated results from the derived expression, the applicability of the theoretical expression for the motor electromagnetic force has been verified and the applied scope of its simplified form is also given.2. By analogy between the electrical, mechanical and acoustic systems, combining with the derived expression of the motor electromagnetic force, an equivalent circuit model for the moving magnet linear compressor has been established, and then the expression for the energy conversion efficiency and the satisfied condition for the maximum efficiency have been obtained based on the model. Moreover, the effects of the coefficient for electrical-mechanical transformer, electromagnet and mechanical equivalent resister are investigated numerically on the maximum energy conversion efficiency.3. Focusing on the important role played by the plate spring for the moving-magnet linear compressor, the finite element method has been applied to analyze the effects of the groove width and thickness on the stress distribution, the radial stiffness and the axial stiffness of a plate spring. Meanwhile, the location of maximum stress of plate spring is indicated by definite element analysis for further design improving. |
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