Closed cycle gas refrigerator

A regrigerator having a working space including a compression space held at a relatively high temperature during operation and having a volume varied according to a displacement of a piston arranged adjacent said compression space or displacements of said piston and a displacer, an expansion space held at a relatively low temperature during operation and having a volume varied according to said displacement of said displacer arranged adjacent said expansion space, a cooler, a regenerator and a freezer disposed between said compression space and said expansion space to communicate therebetween and a working gas filling said working space and performing a thermodynamic cycle by movements of said piston and said displacer in different phase to generate a cold production therein, comprising a linear motor including an armature coil and a closed magnetic circuit for driving said piston, a support spring for supporting said piston in a constant position in a stationary condition and a power source for driving said armature coil, wherein an angular resonance frequency .omega. of a reciprocation portion including said piston and a portion of said linear motor is defined by the following equation:

• ##EQU5## where m=total mass of said reciprocation portion
• SP=area of a working surface of said piston
• Pa=amplitude of pressure variation of said working gas in said compression space
• .alpha.=phase difference between a displacement of said piston and pressure variation of said working gas in said compression space
• S=stroke of said piston
• Ks=spring constant of said support spring and wherein an angular frequency of said power source .omega..sub.o is substantially equal to said angular resonance frequency .omega. with an acceptable error therebetween being .+-.10%.