A screw compressor includes a casing having an outer peripheral wall, and a compression mechanism. The compression mechanism includes a screw rotor with helical grooves, a gate rotor with a plurality of gates meshing with the helical grooves, and a cylinder housing the screw rotor. The compression mechanism is disposed inward of the outer peripheral wall. The outer peripheral wall has a discharge passage through which a fluid compressed in the compression mechanism flows. The discharge passage includes an inner peripheral passage formed along an outer peripheral surface of the cylinder, and an outer peripheral passage formed along the inner peripheral passage and the outer peripheral wall. The inner and outer peripheral passages are formed so that the fluid compressed in the compression mechanism sequentially flows through the inner and outer peripheral passages.

A single-screw compressor includes a screw rotor with a helical groove, a cylindrical wall rotatably housing the screw rotor, a gap adjuster mechanism, and a gear-shaped gate rotor having a plurality of flat gates. The gate rotor is arranged outside the wall. Some of the gates enter a space inside the wall via an opening formed in the cylindrical wall and mesh with the screw rotor. A fluid is compressed in a compression chamber defined in the helical move by the screw rotor, the gates meshing with the screw rotor, and the wall. The gap adjuster mechanism avoids contact between a front surface of the gate rotor toward the compression chamber and a sealing surface of the wall facing the front surface, by displacing at least one of the gate rotor and the sealing surface of the wall in an axial direction of the gate rotor.

A single-screw compressor includes a screw rotor with a helical groove, a cylindrical wall rotatably housing the screw rotor, a gap adjuster mechanism, and a gear-shaped gate rotor having a plurality of flat gates. The gate rotor is arranged outside the wall. Some of the gates enter a space inside the wall via an opening formed in the cylindrical wall and mesh with the screw rotor. A fluid is compressed in a compression chamber defined in the helical move by the screw rotor, the gates meshing with the screw rotor, and the wall. The gap adjuster mechanism avoids contact between a front surface of the gate rotor toward the compression chamber and a sealing surface of the wall facing the front surface, by displacing at least one of the gate rotor and the sealing surface of the wall in an axial direction of the gate rotor.

A screw compressor includes an internal-volume-ratio variable mechanism including a variable Vi valve configured to make a Vi value being an internal volume ratio variable. The screw compressor controls a position of the variable Vi valve in two stages. The position of the variable Vi valve when the Vi value is set to be large is set to attain a Vi value with which a compressor efficiency during operation under a predetermined high-load condition or a predetermined high-compression-ratio condition is equal to or higher than a set efficiency set in advance.

A screw compressor includes a casing, a screw rotor, a discharge passage, and at least one muffler space. The casing includes a cylindrically-shaped cylinder, a main body surrounding a vicinity of the cylinder, and a high-pressure fluid passage provided between the main body and the cylinder. The screw rotor includes a plurality of helical grooves. The screw rotor is inserted into the cylinder to define fluid chambers. A fluid is sucked into the fluid chambers to compress the fluid. The discharge passage is disposed in the casing. The discharge passage guides the fluid that has been discharged from the fluid chambers to the high-pressure fluid passage. The at least one muffler space is disposed in the casing. The at least one muffler space communicates with the discharge passage so as to reduce a pressure fluctuation of the fluid flowing from the discharge passage to the high-pressure fluid passage.

A screw compressor includes a casing, a screw rotor, a discharge passage, and at least one muffler space. The casing includes a cylindrically-shaped cylinder, a main body surrounding a vicinity of the cylinder, and a high-pressure fluid passage provided between the main body and the cylinder. The screw rotor includes a plurality of helical grooves. The screw rotor is inserted into the cylinder to define fluid chambers. A fluid is sucked into the fluid chambers to compress the fluid. The discharge passage is disposed in the casing. The discharge passage guides the fluid that has been discharged from the fluid chambers to the high-pressure fluid passage. The at least one muffler space is disposed in the casing. The at least one muffler space communicates with the discharge passage so as to reduce a pressure fluctuation of the fluid flowing from the discharge passage to the high-pressure fluid passage.

A high suction pressure thrust load balance assembly configured for use with a single screw compressor includes comprises a sealing baffle that is keyed to, so as to be rotatable along with, a main rotor drive shaft of the single screw compressor. The sealing baffle is configured to create a force or load to counteract the axial force of the main rotor drive shaft created during rotation of the main rotor drive shaft using the pressurized oil used to lubricate the mechanical shaft seal of the compressor.

A high suction pressure thrust load balance assembly configured for use with a single screw compressor includes comprises a sealing baffle that is keyed to, so as to be rotatable along with, a main rotor drive shaft of the single screw compressor. The sealing baffle is configured to create a force or load to counteract the axial force of the main rotor drive shaft created during rotation of the main rotor drive shaft using the pressurized oil used to lubricate the mechanical shaft seal of the compressor.

A screw compressor includes a casing, a motor provided in the casing, a screw rotor inserted into a cylinder in the casing, a bearing holder, a drive shaft, a first bearing, and a second bearing. The cylinder is formed on a lateral side of the motor. The bearing holder is disposed on an opposite side of the screw rotor from the motor and adjacent to the screw rotor. The drive shaft is connected to the motor and the screw rotor. The first bearing is disposed adjacent to the screw rotor. The second bearing is disposed adjacent to the motor in an axial direction of the drive shaft. At least a portion of the first bearing is disposed inside the screw rotor.

A screw compressor includes a casing, a motor provided in the casing, a screw rotor inserted into a cylinder in the casing, a bearing holder, a drive shaft, a first bearing, and a second bearing. The cylinder is formed on a lateral side of the motor. The bearing holder is disposed on an opposite side of the screw rotor from the motor and adjacent to the screw rotor. The drive shaft is connected to the motor and the screw rotor. The first bearing is disposed adjacent to the screw rotor. The second bearing is disposed adjacent to the motor in an axial direction of the drive shaft. At least a portion of the first bearing is disposed inside the screw rotor.