SCREW COMPRESSOR AND REFRIGERATION CYCLE DEVICE

A screw compressor includes a casing (1), a screw rotor (3) rotatable in the casing (1), a compression chamber (5) defined between the casing (1) and the screw rotor (3) to compress refrigerant gas, a slide groove (1a) disposed on the inner peripheral surface of the casing (1) and extending along the direction of the rotational axis of the screw rotor (3), an economizer gas passage (1b) extending through the casing (1) to communicate the outside of the casing (1) with the slide groove (1a), a slidable valve (8) disposed in the slide groove (1a) so as to be slidable along the direction of the rotational axis of the screw rotor (3), and an economizer port (8a) penetrating through the slidable valve (8) to communicate the economizer gas passage (1b) with the compression chamber (5) depending on the position of the slidable valve (8), wherein the slidable valve (8) moves between a first position, which allows the economizer gas passage (1b) to communicate with the compression chamber (5), and a second position, which prevents the economizer port (8a) from communicating with the compression chamber (5).