Vibration Analysis of Linear Motor Driven Stirling Cryocooler Coupled with a Pneumatically Driven Expander

Linear motors are widely utilized in free-piston Stirling cryocoolers due to their high efficiency, high reliability, and low noise. The reciprocating motions of the linear motor moving piston and the expander displacer leads to an inevitable harmful vibration output. Most researches only focused on the vibration of a single moving component, while few studies discussed about the coupling vibration of linear compressor and expander. In this paper, the vibration of a linear motor-driven Stirling cryocooler is studied through theoretical analysis and experiments. A passive absorber is designed to suppress the vibration output of the linear compressor and expander simultaneously. The dynamic model of the Stirling cryocooler is established, and the transfer function of the system's driving voltage and displacement is derived. The influence of motor thrust constant, resistance and inductance on the system's vibration output is investigated. The experimental results are presented to evaluate the validity of the proposed model.