Screw compressor

Abstract

A screw compressor includes a screw rotor, a gate rotor, and a casing that form a compression chamber. A case outlet is formed in a case outer wall of the casing. A discharge port communicates with the case outlet, and is formed in a portion of the casing facing the compression chamber. The discharge port has first and second end on first and second opposite sides in the axial direction. The case outlet is located between a first position away from the first end toward the first side in the axial direction by a radius of the gate and a second position away from the second end toward the second side in the axial direction by the radius of the gate. The case outlet is located closer to the discharge port than to the screw rotor in the radial direction.

1 . A screw compressor, comprising:
 a screw rotor having a screw groove, the screw rotor extending in an axial direction;   a gate rotor having a gate that meshes with the screw groove; and   a casing rotatably holding the screw rotor, the casing covering the screw rotor from outside in a radial direction orthogonal to the axial direction,   the screw rotor, the gate rotor, and the casing forming a compression chamber that compresses a fluid,   a case outlet being formed in a case outer wall of the casing outside in the radial direction, the fluid being discharged through the case outlet,   a discharge port communicating with the case outlet, the discharge port being formed in a portion of the casing facing the compression chamber,   the discharge port having
 a first end on a first side in the axial direction and 
 a second end on a second side opposite to the first side in the axial direction, 
   the case outlet being located between
 a first position away from the first end toward the first side in the axial direction by a radius of the gate and 
 a second position away from the second end toward the second side in the axial direction by the radius of the gate, 
   the case outlet being located closer to the discharge port than to the screw rotor in the radial direction.   
     
     
         2 . The screw compressor of  claim 1 , wherein
 the gate rotor is housed in a gate rotor chamber provided in the casing, the case outer wall is provided with a gate opening communicating with the gate rotor chamber,   the case outlet and the gate opening are covered with a cap, and   the cap is provided with a cap-side discharge passage communicating with the case outlet.   
     
     
         3 . The screw compressor of  claim 2 , wherein
 the case outlet is flush with a case-side mounting surface of the case outer wall on which the cap is mounted, and   the case-side mounting surface and the cap are sealed with a first seal member.   
     
     
         4 . The screw compressor of  claim 2 , wherein
 the cap-side discharge passage includes a cap-side insertion pipe inserted into the case outlet, and   the case outlet and the cap-side insertion pipe are sealed with a second seal member.   
     
     
         5 . The screw compressor of  claim 1 , wherein
 the case outlet is located to overlap with the discharge port in the axial direction.   
     
     
         6 . The screw compressor of  claim 1 , wherein
 the casing is provided with a connection passage that connects the case outlet and the discharge port, and   the connection passage extends straight.   
     
     
         7 . The screw compressor of  claim 1 , wherein
 a discharge pipe is connected to the case outlet, and   the discharge pipe is provided with a silencer.   
     
     
         8 . The screw compressor of  claim 1 , further comprising:
 a bearing holder that holds a bearing supporting the screw rotor; and   a holding member that presses the bearing holder in the axial direction, the holding member being plate-shaped and having a thickness direction in the axial direction.   
     
     
         9 . The screw compressor of  claim 1 , further comprising:
 a slide valve that moves in the axial direction to adjust an opening degree of the discharge port.   
     
     
         10 . The screw compressor of  claim 1 , wherein
 the gate rotor includes a first gate rotor and a second gate rotor,   the compression chamber includes
 a first compression chamber formed by the screw rotor, the first gate rotor, and the casing, and 
 a second compression chamber formed by the screw rotor, the second gate rotor, and the casing, 
   the case outlet includes a first case outlet and a second case outlet formed in the case outer wall,   the discharge port includes
 a first discharge port formed in a portion of the casing facing the first compression chamber, and 
 a second discharge port formed in a portion of the casing facing the second compression chamber, 
   the first discharge port communicates with the first case outlet,   the second discharge port communicates with the second case outlet, and   the first case outlet and the second case outlet are located at different positions in a circumferential direction of the screw rotor.   
     
     
         11 . The screw compressor of  claim 10 , wherein
 the first compression chamber compresses the fluid at a first pressure to an intermediate pressure higher than the first pressure,   the second compression chamber compresses the fluid at the intermediate pressure to a second pressure higher than the intermediate pressure, and   the fluid flows through the first compression chamber, the first discharge port, the first case outlet, the second compression chamber, the second discharge port, and the second case outlet in order.   
     
     
         12 . The screw compressor of  claim 1 , wherein
 the gate rotor includes a first gate rotor and a second gate rotor,   the compression chamber includes
 a first compression chamber formed by the screw rotor, the first gate rotor, and the casing, and 
 a second compression chamber formed by the screw rotor, the second gate rotor, and the casing, 
   the case outlet includes a first case outlet and a second case outlet formed in the case outer wall,   the discharge port includes
 a first discharge port formed in a portion of the casing facing the first compression chamber, and 
 a second discharge port formed in a portion of the casing facing the second compression chamber, 
   the first discharge port communicates with the first case outlet,   the second discharge port communicates with the second case outlet,   a first discharge pipe is connected to the first case outlet,   a second discharge pipe is connected to the second case outlet,   the first discharge pipe and the second discharge pipe merge with each other at a merge portion, and   a pulsation of the fluid flowing from the first discharge port to the merge portion through the first case outlet and the first discharge pipe and a pulsation of the fluid flowing from the second discharge port to the merge portion through the second case outlet and the second discharge pipe cancel each other.