Booster-type gas compressor

Abstract

In a booster-type gas compressor, an electric motor in a motor case drives a crank shaft integrally connected to a driving shaft. The crank shaft is coupled to a piston rod extending perpendicular to the crank shaft and having a piston at the upper end. Rotation of the crank shaft allows the piston up and down. A compressed gas from a compressed-gas flow path is fed to a compressing chamber above the piston and further compressed by the piston. A bypath conduit connects the compressed-gas flow path to the motor case to keep pressure in the crank case to more than atmospheric pressure.

1 . A booster-type gas compressor comprising: 
 a crank case;    a crank shaft in the crank case;    a driving shaft integrally connected to the crank shaft;    a motor case;    an electric motor joined to the driving shaft to drive the driving shaft in the motor case;    a cylinder;    a piston in the cylinder;    a piston rod joined to the piston at an upper end and to the crank shaft at a lower end;    a compressed-gas flow path that feeds a compressed gas into a compressing chamber above the piston to further compress the gas; and    a bypath conduit that connects the compressed-gas flow path to the crank case to keep pressure in the crank case to more than atmospheric pressure.    
   
   
       2 . A compressed of  claim 1  further comprising a pressure regulator at the bypath conduit.  
   
   
       3 . A compressor of  claim 1  further comprising a pressure regulator at the crank case.  
   
   
       4 . A compressor of  claim 1  further comprising a pressure regulator at the compressed-gas flow path between the bypath conduit and the cylinder.