Hitachi, Ltd.

Hitachi Appliances, Inc

Hitachi, Ltd., Trustee, for the Benefit of Hitachi Air Conditioning Systems Co., Ltd.

Johnson Controls-hitachi Air Conditioning Technology (hong Kong) Limited

Masayuki Urashin

Shigekazu Nozawa

Takeshi Hida

Hirotaka Kameya

Atsushi Watanabe

Hiroki Ohsumimoto

Noriyuki Yamazaki

Hiroki Osumimoto

Masakazu Aoki

Kazuhiko Kawaike

Hiroaki Kuno

Hiroshi Takagi

Minetoshi Izushi

Motomichi Doi

Mitsuhiko Miyagawa

Shinichiro Yamada

Yoshikazu Ishiki

Masanori Agekura

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.

Piston operated bypass valve for a screw compressor

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.

Screw compressor

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.

Screw compressor and method of manufacturing rotor for the same

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.

Compressor with oil-mist separator

The screw compressor according to the invention is provided with a main casing having male and female rotors , a discharge casing having a discharge passage for compressed gas discharged from the rotors, and an oil reservoir for accumulating oil separated from the compressed gas. The discharge casing is provided with a cylindrical oil separating space section 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 is provided so as to communicate with the oil separating space section, and a cylindrical member 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.

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.

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. That is, a relationship between a radius of a point of contact on a leading surface side of the female rotor and a radius of a point of contact on a trailing surface side or curvatures of the rotors are such that the negative torque is not generated on the lobe profile.

Screw fluid machine

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. The lubricant for each of the second radial plain bearings and for a corresponding one of the thrust plain bearings is fed to a space between the second radial plain bearing and the thrust plain bearing, and is distributed to the second radial plain bearing more in amount than that fed to the thrust bearing due to a difference between flow resistance with which the lubricant passes through the second radial plain bearing and flow resistance with which the lubricant passes through the thrust plain bearing.

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.

Growing community of inventors

Shizuoka, Japan

Masayuki Urashin