Screw Compressor

Abstract

A screw compressor that enhances performance of a compressor main unit and a motor is provided. The screw compressor includes an oil-injected compressor main unit that compresses air with injecting oil in a compression chamber and an axial-gap motor that drives the compressor main unit. A male rotor of the compressor main unit has a suction-side shaft portion connected coaxially with a rotor shaft of the motor. The screw compressor further includes a suction-side bearing that rotatably supports the suction-side shaft portion of the male rotor. The suction-side bearing restricts axial movement of the suction-side shaft portion and bears a radial load and axial loads in both directions.

1 . A screw compressor including a liquid-injected compressor main unit that includes a screw rotor and compresses gas with injecting liquid in a compression chamber defined by a tooth groove of the screw rotor and an axial-gap motor that drives the compressor main unit, the screw rotor having a motor-side shaft portion connected coaxially with a rotor shaft of the motor, the screw compressor comprising:
 a bearing that rotatably supports the motor-side shaft portion of the screw rotor, wherein   the bearing restricts axial movement of the motor-side shaft portion and bears a radial load and axial loads in both directions.   
     
     
         2 . The screw compressor according to  claim 1 , wherein
 the compression chamber of the compressor main unit draws in gas via a suction port on a side adjacent to the motor and discharges compressed gas via a discharge port on a side opposite to the motor, and   the motor-side shaft portion is a suction-side shaft portion.   
     
     
         3 . The screw compressor according to  claim 2 , further comprising:
 a gas-liquid separator, disposed on a discharge side of the compressor main unit, for separating the liquid from the compressed gas discharged from the compressor main unit.   
     
     
         4 . The screw compressor according to  claim 1 , wherein
 the motor includes a first rotor disposed on an output side of the rotor shaft, a second rotor disposed on a non-output side of the rotor shaft, and a stator disposed between the first rotor and the second rotor, and   a dimension of a gap between the first rotor and the stator is greater than a dimension of a gap between the second rotor and the stator at room temperature.   
     
     
         5 . The screw compressor according to  claim 1 , wherein
 the motor includes a rotor disposed on the rotor shaft, a first stator disposed on an output side with respect to the rotor, and a second stator disposed on a non-output side with respect to the rotor, and   a dimension of a gap between the rotor and the first stator is smaller than a dimension of a gap between the rotor and the second stator at room temperature.   
     
     
         6 . The screw compressor according to  claim 1 , wherein
 the bearing includes combined angular contact ball bearings for face to face type or back to back type, and is held at a fixed position within a casing.