Patent ID: 8562319

Claim:
A screw compressor comprising: a screw rotor provided with a plurality of helical grooves forming fluid chambers; a casing including a cylinder portion with the screw rotor disposed therein; a low pressure space formed in the casing to receive a flow of uncompressed, low pressure fluid; a bypass passage opened in an inner peripheral surface of the cylinder portion to communicate the fluid chamber with the low pressure space; and a slide valve slideable in an axial direction of the screw rotor to change an area of an opening of the bypass passage in the inner peripheral surface of the cylinder portion, an end face of the slide valve facing the bypass passage being inclined along an extending direction of the helical grooves, part of an outer peripheral surface of the screw rotor sandwiched between two adjacent helical grooves forming a circumferential sealing face slideable on the inner peripheral surface of the cylinder portion to seal between the two adjacent helical grooves, an edge of the circumferential sealing face positioned forward in a direction of rotation of the screw rotor forming a front edge of the circumferential sealing face, an edge of the end face of the slide valve adjacent to the screw rotor forming a screw-side edge, and the screw-side edge of the slide valve being parallel to the front edge of the circumferential sealing face of the screw rotor.