Abstract: A screw compressor includes a screw rotor having a plurality of screw grooves, a plurality of gate rotors each including gates that mesh with the screw rotor, and a casing. The screw rotor is rotatably inserted in the casing. The casing has a cylindrical wall through which the gates pass. The screw compressor has a plurality of compression chambers inside the cylindrical wall. The plurality of compression chambers are defined by the screw rotor and the gates. The compression chambers include a first compression chamber and a second compression chamber. A fluid introduced into the casing at a suction pressure is compressed to an intermediate pressure higher than the suction pressure in the first compression chamber. The fluid at the intermediate pressure is compressed to a discharge pressure higher than the intermediate pressure in the second compression chamber.

Abstract: A screw compressor includes a screw rotor having a plurality of screw grooves, a plurality of gate rotors each including gates that mesh with the screw rotor, and a casing. The screw rotor is rotatably inserted in the casing. The casing has a cylindrical wall through which the gates pass. The screw compressor has a plurality of compression chambers inside the cylindrical wall. The plurality of compression chambers are defined by the screw rotor and the gates. The compression chambers include a first compression chamber and a second compression chamber. A fluid introduced into the casing at a suction pressure is compressed to an intermediate pressure higher than the suction pressure in the first compression chamber. The fluid at the intermediate pressure is compressed to a discharge pressure higher than the intermediate pressure in the second compression chamber.

Abstract: A screw compressor includes a casing, a screw rotor, an oil sump containing lubricant oil, a lubrication passage and a flow rate controller. The screw rotor is inserted in a cylinder portion of the casing to form a fluid chamber. The screw rotor rotates to suck a fluid into the fluid chamber for compression. The lubrication passage supplies the lubricant oil in the oil sump to the fluid chamber due to a difference in pressure between the oil sump and the fluid chamber. The flow rate controller reduces a flow rate of the lubricant oil supplied to the fluid chamber in accordance with a decrease in operating capacity of the screw compressor.

Abstract: A screw compressor includes a screw rotor having a plurality of helical grooves, a casing containing the screw rotor and a gate rotor. The casing includes a discharge port on an inner peripheral surface of the casing. The gate rotor has gates meshing with the helical grooves of the screw rotor to compress gas in compression chambers to discharge the gas from the discharge port after being compressed. The compression chambers are defined by the helical grooves, the casing, and the gates. The discharge port is divided into a first port and a second port when two adjacent helical grooves of the plurality of helical grooves is open to the discharge port as a result of rotation of the screw rotor, with one of the two adjacent helical grooves being open in the first port and the other of the two adjacent helical grooves being open in the second port.

Abstract: A compressor includes a casing, a screw rotor, a slide member with at least one economizer port, and a control unit controlling a position of the slide member along the axis of the screw rotor to position the at least one economizer port based on the rotating speed of the screw rotor to advance the timing of opening of the at least one economizer port. The controller controls the position of the slide member along the axis such that the slide member moves upstream toward a suction side of the compressor when the rotating speed of the screw rotor increases, and downstream toward a discharge side of the compressor when the rotating speed of the screw rotor decreases. A refrigerating apparatus includes the compressor, a condenser, a heat exchanger, an expansion unit, and an evaporator, sequentially connected, and has an economizer line.

Abstract: A screw compressor includes a screw rotor, a gate rotor and an injection mechanism. The screw rotor is provided with multiple helical grooves. The gate rotor is provided with multiple gates meshing with the helical grooves to form at least one compression chamber between at least one of the helical grooves and at least one of the gates. The compression chamber is configured and arranged such that refrigerant taken-in from a starting-end side of the helical groove is compressed and discharged from a dead-end side of the helical groove. The injection mechanism is configured and arranged to inject oil or refrigerant from a discharge hole of the injection mechanism into the compression chamber such that rotational torque is imparted in a direction in which the screw rotor is rotated at a time of compression.

Abstract: A screw compressor includes a screw rotor, a casing, a low pressure space, a bypass passage and a slide valve. The screw rotor is provided with a plurality of helical grooves forming fluid chambers. The casing includes a cylinder portion with the screw rotor disposed in the cylinder portion. The low pressure space is formed in the casing to receive a flow of uncompressed, low pressure fluid. The bypass passage is opened in an inner peripheral surface of the cylinder portion to communicate the fluid chamber with the low pressure space. The slide valve is 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 is inclined along an extending direction of the helical grooves.

Abstract: A screw compressor includes a casing, a screw rotor and a gate rotor. The casing has a cylinder. The screw rotor is cylindrical-shaped and configured to be fitted into the cylinder. The gate rotor is configured to be engaged with the screw rotor. A, outlet width of a seal surface of the casing on a gas-outlet side of the screw rotor is larger than an inlet width of the seal surface on a gas-inlet side of the screw rotor. The seal surface of the casing is opposed to one surface of the gate rotor.

Abstract: A screw compressor includes a screw rotor, a casing, a low pressure space, a bypass passage and a slide valve. The screw rotor is provided with a plurality of helical grooves forming fluid chambers. The casing includes a cylinder portion with the screw rotor disposed in the cylinder portion. The low pressure space is formed in the casing to receive a flow of uncompressed, low pressure fluid. The bypass passage is opened in an inner peripheral surface of the cylinder portion to communicate the fluid chamber with the low pressure space. The slide valve is slideable in an axial direction of the screw rotor to chance an area of an opening of the brass passage inner peripheral surface of the cylinder portion. An end face of the slide valve facing the by bypass passage is inclined along an extending direction of the helical grooves.

Abstract: A screw compressor includes a casing, a screw rotor, an oil sump containing lubricant oil, a lubrication passage and a flow rate controller. The screw rotor is inserted in a cylinder portion of the casing to form a fluid chamber. The screw rotor rotates to suck a fluid into the fluid chamber for compression. The lubrication passage supplies the lubricant oil in the oil sump to the fluid chamber due to a difference in pressure between the oil sump and the fluid chamber. The flow rate controller reduces a flow rate of the lubricant oil supplied to the fluid chamber in accordance with a decrease in operating capacity of the screw compressor.

Abstract: A screw compressor includes a screw rotor, a gate rotor and an injection mechanism. The screw rotor is provided with multiple helical grooves. The gate rotor is provided with multiple gates meshing with the helical grooves to form at least one compression chamber between at least one of the helical grooves and at least one of the gates. The compression chamber is configured and arranged such that refrigerant taken-in from a starting-end side of the helical groove is compressed and discharged from a dead-end side of the helical groove. The injection mechanism is configured and arranged to inject oil or refrigerant from a discharge hole of the injection mechanism into the compression chamber such that rotational torque is imparted in a direction in which the screw rotor is rotated at a time of compression.

Abstract: A screw compressor includes a screw rotor having a plurality of helical grooves, a casing containing the screw rotor and a gate rotor. The casing includes a discharge port on an inner peripheral surface of the casing. The gate rotor has gates meshing with the helical grooves of the screw rotor to compress gas in compression chambers to discharge the gas from the discharge port after being compressed. The compression chambers are defined by the helical grooves, the casing, and the gates. The discharge port is divided into a first port and a second port when two adjacent helical grooves of the plurality of helical grooves is open to the discharge port as a result of rotation of the screw rotor, with one of the two adjacent helical grooves being open in the first port and the other of the two adjacent helical grooves being open in the second port.

Abstract: A screw compressor includes a casing having a cylinder, a cylindrical-shaped screw rotor disposed in the cylinder, a gate rotor and a seal portion. The screw rotor has a plurality of spiral-shaped groove portions formed in an outer peripheral surface. The gate rotor has a plurality of tooth portions engaged with the groove portions of the screw rotor to define compression chambers on one side of the gate rotor. The tooth portions are formed at an outer peripheral surface of the gate rotor. The seal portion is disposed on a side of the gate rotor opposite to the one side where the compression chambers are defined. The seal portion is arranged to block a space between a neighboring pair of the tooth portions of the gate rotor.

Abstract: A compressor includes a casing, a screw rotor fitted in the casing, at least one economizer port, and a control unit. The at least one economizer port is arranged to discharge refrigerant into compression chambers formed between the casing and the screw rotor. The control unit is configured to advance timing of opening of the at least one economizer port to the compression chambers in accordance with increase in rotating speed of the screw rotor.

Abstract: A screw compressor includes a casing, a screw rotor and a gate rotor. The casing has a cylinder. The screw rotor is cylindrical-shaped and configured to be fitted into the cylinder. The gate rotor is configured to be engaged with the screw rotor. A, outlet width of a seal surface of the casing on a gas-outlet side of the screw rotor is larger than an inlet width of the seal surface on a gas-inlet side of the screw rotor. The seal surface of the casing is opposed to one surface of the gate rotor.

Abstract: Regulating compression capability to a load is performed by an inverter (15) that regulates revolution number of an electric motor (11). This makes unload control in capability regulation unnecessary, preventing operational efficiency from lowering. Further, a capacity control valve for capacity control is eliminated for a simplified valve control mechanism. Regulating a variable inner volume ratio achieves the highest compressor efficiency corresponding to operating condition (capability). When a low inner volume ratio command is issued, a slide valve (19) is moved by a compression section controller (27) in an axial direction toward the electric motor (11). This advances completion time of a compression step to advance discharge of a compressed gas. When a high inner volume ratio command is issued, the slide valve (19) is moved in an axial direction toward a piston (25), which delays time of completion of compression step to delay discharge of a compressed gas.