Screw compressor

Abstract

A screw compressor includes a casing having a cylinder, a cylindrical-shaped screw rotor disposed in the cylinder, a gate rotor and a seal portion. The screw rotor has a plurality of spiral-shaped groove portions formed in an outer peripheral surface. The gate rotor has a plurality of tooth portions engaged with the groove portions of the screw rotor to define compression chambers on one side of the gate rotor. The tooth portions are formed at an outer peripheral surface of the gate rotor. The seal portion is disposed on a side of the gate rotor opposite to the one side where the compression chambers are defined. The seal portion is arranged to block a space between a neighboring pair of the tooth portions of the gate rotor.

1 . A screw compressor comprising:
 a casing having a cylinder;   a cylindrical-shaped screw rotor disposed in the cylinder, the screw rotor having a plurality of spiral-shaped groove portions formed in an outer peripheral surface thereof;   a gate rotor having a plurality of tooth portions engaged with the groove portions of the screw rotor to define compression chambers on one side of the gate rotor, the tooth portions being formed at an outer peripheral surface of the gate rotor; and   a seal portion disposed on a side of the gate rotor opposite to the one side where the compression chambers are defined,   the seal portion being arranged to block a space between a neighboring pair of the tooth portions of the gate rotor.   
     
     
         2 . The screw compressor as claimed in  claim 1 , wherein
 the casing has a seal surface facing a surface of the gate rotor on the one side of the gate rotor where the compression chambers are defined, and   a surface of the seal portion facing the seal surface has a shape substantially corresponding to a shape of part of the seal surface facing to the seal portion with the gate rotor being interposed therebetween.   
     
     
         3 . The screw compressor as claimed in  claim 1 , wherein
 the casing, the screw rotor, the gate rotor and the seal portions are configured and arranged such that
 gas is sucked into the compression chambers from a suction side of one end of the screw rotor along a shaft direction, and 
 the gas within the compression chambers is discharged from a discharge side of the other end of the screw rotor along the shaft direction after being compressed, and 
   the seal portion is provided more on the discharge side along the shaft direction of the screw rotor than a plane containing a shaft of the gate rotor perpendicular to the shaft direction of the screw rotor.   
     
     
         4 . The screw compressor as claimed in  claim 1 , wherein
 a material of the seal portion is polyphenylene sulfide resin.   
     
     
         5 . The screw compressor as claimed in  claim 2 , wherein
 the casing, the screw rotor, the gate rotor and the seal portions are configured and arranged such that
 gas is sucked into the compression chambers from a suction side of one end of the screw rotor along a shaft direction, and 
 the gas within the compression chambers is discharged from a discharge side of the other end of the screw rotor along the shaft direction after being compressed, and 
   the seal portion is provided more on the discharge side along the shaft direction of the screw rotor than a plane containing a shaft of the gate rotor perpendicular to the shaft direction of the screw rotor.   
     
     
         6 . The screw compressor as claimed in  claim 5 , wherein
 a material of the seal portion is polyphenylene sulfide resin.   
     
     
         7 . The screw compressor as claimed in  claim 2 , wherein
 a material of the seal portion is polyphenylene sulfide resin.   
     
     
         8 . The screw compressor as claimed in  claim 3 , wherein
 a material of the seal portion is polyphenylene sulfide resin.