Screw compressor

Abstract

This screw compressor is provided with a screw rotor, a casing accommodating the screw rotor, and a liquid feed mechanism for feeding a liquid into an operating chamber enclosed by the casing, wherein the pitch of the screw rotor changes in the axial direction from a suction end surface toward a discharge end surface.

1 . A screw compressor comprising:
 a screw rotor;   a casing which accommodates the screw rotor; and   a liquid feed mechanism configured to feed a liquid into an operating chamber enclosed by the casing,   wherein the pitch of the screw rotor decreases monotonically in the axial direction from the suction end face to the discharge end surface and from the suction end face to the discharge end face,   wherein the shape and dimensions of the axially perpendicular cross-section of the screw rotor and the screw rotor, the total winding angle, and the pressure of the operating chamber communicated with the liquid feed port installed at a position on the inner wall of the bore in the screw rotor having the same length and evenly spaced pitch, and   wherein the liquid feed mechanism is disposed at a position higher than the pressure of the operating chamber in which the liquid feed port installed at the same position of the screw rotor communicates.   
     
     
         2 . The screw compressor according to  claim 1 ,
 wherein the liquid feed mechanism is disposed at a position in which a pressure of the operating chamber communicating with a liquid feed port installed at a certain position of an inner wall of a bore in a screw rotor having an equal pitch and having a shape and a dimension of a cross-section orthogonal to the axial direction of the screw rotor, a total winding angle, and a length which are the same as those of the screw rotor becomes higher than a pressure of the operating chamber communicating with a liquid feed port installed at the same position as the screw rotor.   
     
     
         3 . In the screw compressor according to  claim 1 ,
 wherein the liquid feed mechanism is disposed on the suction end surface in relation to a surface parallel to the suction end surface and the discharge end surface and including a point in which a helix angle of the screw rotor is the same as a helix angle of a screw rotor having an equal pitch and having a shape and a dimension of a cross-section orthogonal to the axial direction of the screw rotor, a total winding angle, and a length which are the same as those of the screw rotor.