Variable capacity bypass valve for screw compressor

A screw compressor comprising:

• a compressor housing defining a compression chamber having a compression chamber outlet end and a plurality of bypass ports communicating with the compression chamber;
• a spiral valve positioned adjacent the plurality of bypass ports communicating with the compression chamber, the spiral valve comprising a shutter configured to selectively open and close one or more of the plurality of bypass ports based on a rotational position;
• and
• a variable capacity bypass valve comprising:
• a bore formed in a rotor bore discharge face of the compressor housing upstream of a compression chamber outlet end of the compression chamber;
• a slide valve member inserted into the bore to fill a cavity formed in the rotor bore discharge face of the compressor housing, the valve member having a sealing surface configured to interact with a thread of a compressor screw during operation of the screw compressor;
• and
• an actuator structure coupled to the valve member and oriented to move the valve member radially along the bore to open a fluid pathway communicatively coupling the compression chamber to a bypass chamber housing the spiral valve, the bypass chamber configured to return compressed fluid to a fluid inlet of the compression chamber,
• wherein the valve member of the variable capacity bypass valve has a partial cylindrical shape with an opened region on a side opposite the sealing surface in an axial direction of the screw compressor.

A variable capacity bypass valve for a screw compressor having a compressor housing defining a compression chamber, the variable capacity bypass valve comprising:

• a bore formed in a rotor bore discharge face of the compressor housing upstream of a compression chamber outlet end of the compression chamber;
• a slide valve member inserted into the bore to fill a cavity formed in the rotor bore discharge face of the compressor housing, the valve member having a sealing surface configured to interact with a thread of a compressor screw during operation of the screw compressor;
• and
• an actuator structure coupled to the valve member and oriented to move the valve member radially along the bore to open a fluid pathway communicatively coupling the compression chamber to a bypass chamber configured to return compressed fluid to a fluid inlet of the compression chamber,
• wherein the sealing surface is a flat sealing surface extending parallel to the rotor bore discharge face of the compressor housing, and
• wherein the valve member is aligned in the bore such that the sealing surface protrudes outward from the rotor bore discharge face into the compression chamber.