Abstract: A screw compressor includes a valve hole formed at a discharge side end surface of a discharge casing and at a position opening to a compression work chamber; a bypass flow path having the valve hole and a discharge chamber communicate with each other; and a valve body arranged in the valve hole. The screw compressor also includes cylinder chambers provided on a rear surface side of the valve body; a piston reciprocally moving in the cylinder chambers; a rod connecting the piston and the valve body; communication paths for introducing a fluid on a discharge side into the cylinder chamber on a side opposite to a valve body side of the piston and on the valve body side; a pressure discharge path; a plurality of valve means; and a controller controlling the plurality of valves means.

Abstract: A screw compressor includes a valve hole formed at a discharge side end surface of a discharge casing and at a position opening to a compression work chamber; a bypass flow path having the valve hole and a discharge chamber communicate with each other; and a valve body arranged in the valve hole. The screw compressor also includes cylinder chambers provided on a rear surface side of the valve body; a piston reciprocally moving in the cylinder chambers; a rod connecting the piston and the valve body; communication paths for introducing a fluid on a discharge side into the cylinder chamber on a side opposite to a valve body side of the piston and on the valve body side; a pressure discharge path; a plurality of valve means; and a controller controlling the plurality of valves means.

Abstract: In order to obtain a screw compressor which is small in size and weight and has ease of maintenance and high reliability, the screw compressor comprises a screw rotor, a low-pressure-side bearing and a high-pressure-side bearing which support the screw rotor, a motor which drives the screw rotor, a motor casing which accommodates the motor, a main casing which accommodates the screw rotor and the low-pressure-side bearing, and a discharge casing which accommodates the high-pressure-side bearing. The motor casing, the main casing, and the discharge casing are accommodated in a steel pipe chamber, and the steel pipe chamber includes a low-pressure-side chamber and a high-pressure-side chamber which are able to be divided in the axial direction. By using a flange provided on an inner surface of the steel pipe chamber, a flange provided in the main casing, and a sealing component provided between the flanges, the steel pipe chamber is divided into a low-pressure-side space and a high-pressure-side space.

Abstract: A hermetic screw compressor comprises a male rotor, a female rotor engaging the male rotor, an electric motor connected to a low pressure side shaft portion of the male rotor, a low pressure side bearing for supporting the low pressure side shaft portion of each of the rotors, a high pressure side bearing for supporting a high pressure side shaft portion of each of the rotors, and a casing containing the rotors, the electric motors and the bearings. A contact type seal is arranged to seal a part of the low pressure side shaft portion of the male rotor between the low pressure side bearing and the electric motor, and a cover contains the seal and is axially detachably attached to the casing so that the contact type seal is attached to the casing through the cover.

Abstract: An oil separator and an oil reservoir are formed integral with a main casing. Also, an opening communicated with the oil reservoir is formed in a part of a lower portion of an oil separation space of the oil separator. Preferably, the opening is formed so that its width is increased as it approaches an outer peripheral side of the oil separation space from a center thereof. Further, a safety valve is installed so that a line connecting between the safety valve and the center of the oil separator is made substantially in parallel to axes of screw rotors.

Abstract: A screw compressor of which a female rotor is driven by a motor, and of which a male rotor is driven by the female rotor. The male or female rotor is composed of a member which is made of cast iron and is subjected to surface hardening treatment or heat treatment including quenching. The surface hardening treatment may include sulphonitriding or nitiriding treatment. In the case of subjecting the cast iron to the heat treatment, austemper treatment is applied.

Abstract: A screw compressor of which a female rotor is driven by a motor, and of which a male rotor is driven by the female rotor. The male or female rotor is composed of a member which is made of cast iron and is subjected to surface hardening treatment or heat treatment including quenching. The surface hardening treatment may include sulphonitriding or nitiriding treatment. In the case of subjecting the cast iron to the heat treatment, austemper treatment is applied.

Abstract: An oil separator and an oil reservoir are formed integral with a main casing. Also, an opening communicated with the oil reservoir is formed in a part of a lower portion of an oil separation space of the oil separator. Preferably, the opening is formed so that its width is increased as it approaches an outer peripheral side of the oil separation space from a center thereof. Further, a safety valve is installed so that a line connecting between the safety valve and the center of the oil separator is made substantially in parallel to axes of screw rotors.

Abstract: A screw compressor of which a female rotor is driven by a motor, and of which a male rotor is driven by the female rotor. The male or female rotor is composed of a member which is made of cast iron and is subjected to surface hardening treatment or heat treatment including quenching. The surface hardening treatment may include sulphonitriding or nitiriding treatment. In the case of subjecting the cast iron to the heat treatment, austemper treatment is applied.

Abstract: In an oil-mist separator included by a compressor, an inlet passage directs a flow axis of a mixture gas including a mist of lubrication oil and a gas to be taken out of the compressor with a pressurized condition when the mixture gas reaches a chamber, and a discharge port for discharging the gas from the chamber opens in the chamber.

Abstract: The screw compressor according to the invention is provided with a main casing 1 having male and female rotors 6, a discharge casing 3 having a discharge passage 15 for compressed gas discharged from the rotors, and an oil reservoir 19 for accumulating oil separated from the compressed gas. The discharge casing is provided with a cylindrical oil separating space section 4 formed therein so as to communicate with the discharge passage, which discharge passage is connected in a tangential direction of the oil separating space section. Further, a discharge port 14 is provided so as to communicate with the oil separating space section, and a cylindrical member 5 is further provided in the oil separating space section so as to be concentric therewith. The oil separating space section and the oil reservoir are connected to each other through a communication passage having a cross-sectional area smaller than that of the oil separating space section.

Abstract: The screw compressor according to the invention is provided with a main casing 1 having male and female rotors 6, a discharge casing 3 having a discharge passage 15 for compressed gas discharged from the rotors, and an oil reservoir 19 for accumulating oil separated from the compressed gas. The discharge casing is provided with a cylindrical oil separating space section 4 formed therein so as to communicate with the discharge passage, which discharge passage is connected in a tangential direction of the oil separating space section. Further, a discharge port 14 is provided so as to communicate with the oil separating space section, and a cylindrical member 5 is further provided in the oil separating space section so as to be concentric therewith. The oil separating space section and the oil reservoir are connected to each other through a communication passage having a cross-sectional area smaller than that of the oil separating space section.

Abstract: In an oil-mist separator included by a compressor, an inlet passage directs a flow axis of a mixture gas including a mist of lubrication oil and a gas to be taken out of the compressor with a pressurized condition when the mixture gas reaches a chamber, and a discharge port for discharging the gas from the chamber opens in the chamber.

Abstract: Oil separation from discharge gas of a screw compressor is performed with a demister provided in a discharge chamber. For solving unevenness in the speed distribution of the gas in the chamber, at least one auxiliary demister for oil separation is disposed at a local position immediately behind or near the downstream side of an outlet of a discharge passage in a discharge casing so as to be perpendicular to the flow direction of the gas at the outlet. In addition, at least one obstacle plate is disposed on the downstream side of the auxiliary demister.

Abstract: A screw rotor for use in screw compressors and screw vacuum pumps comprises a pair of rotors including a male rotor and a female rotor. These rotors have helical lobes in an axial direction and mesh with each other to form a compression chamber. Depending upon a lobe configuration of the rotors, suction pressure and discharge pressure, a negative torque for self-rotation as well as a positive torque opposing to rotation due to a compression action is generated on the female rotor in operation. This phenomenon generates when a value obtained by integrating a torque acting on the female rotor over an entire cross section in an axial direction of the rotors becomes negative. When the negative torque is generated, noises due to tooth separating vibration is caused. Then, a lobe profile is defined such that a magnitude of the negative torque is smaller than that of the positive torque in respective cross sections of the female rotor.

Abstract: Oil separation from discharge gas of a screw compressor is performed with a demister provided in a discharge chamber. For solving unevenness in the speed distribution of the gas in the chamber, at least one auxiliary demister for oil separation is disposed at a local position immediately behind or near the downstream side of an outlet of a discharge passage in a discharge casing so as to be perpendicular to the flow direction of the gas at the outlet. In addition, at least one obstacle plate is disposed on the downstream side of the auxiliary demister.

Abstract: Oil separation from discharge gas of a screw compressor is performed with a demister provided in a discharge chamber. For solving unevenness in the speed distribution of the gas in the chamber, at least one auxiliary demister for oil separation is disposed at a local position immediately behind or near the downstream side of an outlet of a discharge passage in a discharge casing so as to be perpendicular to the flow direction of the gas at the outlet. In addition, at least one obstacle plate is disposed on the downstream side of the auxiliary demister.

Abstract: A screw compressor comprises a casing and a pair of male and female rotors respectively having herical teeth and grooves formed in their outer peripheries. The rotors are arranged within the casing in meshing relation to each other through the teeth and grooves. Each rotor is rotatably supported by a pair of first and second radial plain bearings and a thrust plain bearing which is arranged at an end of the rotor shaft and adjacent the second radial plain bearing. Each of the thrust plain bearings is of dynamic-pressure type in which with rotation of a corresponding one of the shafts of the respective rotors, pressure is applied to lubricant by sliding movement of the thrust plain bearing to produce an anti-thrust force.

Abstract: About 1 to about 25% by weight of a liquid refrigerant is mixed into a refrigerant gas to be introduced into a screw compressor by suction on the basis of the refrigerant gas in a refrigerator comprising a screw compressor, a condenser, and an expansion valve and an evaporator connected to one another in series. A cooling effect as well as a sealing effect can be satisfactorily attained thereby.