Hitachi, Ltd.

Mitsuru Fujiwara

Katsuhiko Kasuya

Tetsuzo Matsunaga

Akira Suzuki

Yasuo Takahashi

Toshihiro Yamada

Hirotaka Kameya

Tatsuo Natori

Akihiko Yamamoto

Katsumi Matsubara

Masaya Imai

Hidetomo Mori

Kotaro Naya

Motohiro Satoo

Kazuaki Shiinoki

Riichi Uchida

Taiji Hashimoto

Junji Okita

Taisuke Torigoe

Kazuaki Shinoki

A screw-type rotary fluid machine such as a compressor or a vacuum pump has male and female rotors which rotate within a casing, with or without mutual contact. At least one of the male and female rotors being surface-treated to have a treated surface structure. The treated surface structure is a multi-layered structures composed of a plurality of layers including a non-electrolytic Ni plating layer and at least one covering layer of organic resin. The organic resin may be one or more kinds selected from a group of engineering plastics, so as to improve mechanical strength.

Screw-type rotary fluid machine including rotors having treated surfaces

A method treating a surface of rotors in a screw-type rotary fluid machine, with the method comprising the steps of: conducting a non-electrolytic Ni plating on the surface of each rotor so as to form a first layer of non-electrolytic Ni plating layer; heating the rotor having the first layer at a temperature not lower than 500.degree. C.; and forming, at least, a second layer of an organic resin so as to cover the first layer.

Method of treating surfaces of rotors of the screw type rotary machine

In the screw compressing apparatus, by rotating paired male and female rotors as meshing with each other, a gas is suctioned from a suction chamber into a working space, and compressed in the working space. The compressed high pressure gas is exhausted from a exhaust chamber, and then cooled by an aftercooler, thereby producing a low temperature, high pressure gas. In the compression process, the temperature of the gas in the working space becomes high at the exhaust chamber side. When this exhaust gas temperature reaches a predetermined value, a part of the gas cooled by an aftercooler is injected into the working space for lowering the temperture in the working space.

Screw compressing apparatus, rotor temperature control apparatus for

A screw fluid machine in which the distance between a point on each of bore walls and the axis of a male or female rotor decreases at a normal temperature in the vicinity of a high-pressure port as the point proceeds from the low-pressure side to the high-pressure side.

Screw fluid machine with high efficiency bore shape

A screw compressor including a scavenging port, which is separate from a discharge port, located on or in a vicinity of a discharge-side end face of the working space of the casing, for scavenging gas therethrough from a compression chamber near to a completion of a suction stroke. Gas of high temperature leaking from a compression chamber on high-pressure side into a compression chamber on a low-pressure side (in the suction stroke) can be scavenged from the compressor to outside, thereby avoiding a reduction in suction volume efficiency, an increase in consumption of power, and a rise in temperature of gas to be compressed which might otherwise be caused by the gas of high temperature leaking into the compression chambers during a suction stroke.

Screw compressor with scavenging port

A screw compressor having a recess formed in the high-pressure end surface of the casing. This recess receives the fluid from a closed working space which has just been isolated from the discharge port and closed in the compression step. Consequently, the abnormal pressure rise in the closed working space, which is caused due to the compression of the fluid confined, is completely eliminated. The recess has a configuration involving a curve conforming with the leading flank of the female rotor at the instant at which the working space is isolated from the discharge port and closed.

Screw compressor

Rotor tooth forms for a pair of screw rotors in the form of a female rotor and a male rotor, wherein the female rotor has a rotor tooth form including a flank of a surface of advance constituted by an arc and a second order curve, and a flank of a surface of retrocession constituted by a curve generated by an arc of a forward end portion of a lobe on the male rotor and an arc, and the male rotor has a rotor tooth form essentially formed by generating loci of the flank of the surface of advance of the female rotor and the flank of the surface of retrocession thereof.

Rotor tooth form for a screw rotor machine

A screw compressor including a female rotor and a male rotor rotating while meshing with each other, with the rotor tooth form of one of the female and male rotors meshing with each other without any clearance therebetween in normal temperature condition being used as a basic tooth form for obtaining a rotor tooth form produced by deformation on account of thermal expansion during operation. The basic tooth form and the tooth form thus obtained are employed in the assembled compressor. The rotors with these teeth form, when brought together in meshing engagement, have a clearance at start-up which allows for their expansion. This clearance is maintained at a minimum during operation of the compressor.

Screw rotor with tooth form produced by thermal deformation and gear

In a screw rotor including a female rotor member and a male rotor member rotatable about parallel shafts and respectively while meshing with each other, the forward face flank of the female rotor member is composed of a first flank of the forward face formed by a parabolic curve, and a second flank of the forward face formed by a circular arc of a radius R.sub.2, and the backward face flank of the female rotor member is composed of a first flank of the backward face generated by the backward face tooth top flank of the male rotor member having a radius R.sub.5, and a second flank of the backward face formed by a circular arc of a radius R.sub.3 which is smaller than the radius R.sub.2 of the second flank of the forward face flank. The tooth profile of the male rotor member is essentially formed by the forward face flank and the backward face flank of the female rotor member.

Screw rotor with specific tooth profile

An oil-cooled type screw rotor assembly having a female rotor and a male rotor adapted to rotate around parallel axes in meshing relation to each other. The leading side flank of the female rotor is constituted by a first leading side flank formed by an arc of a radius R.sub.1 and a second leading side flank formed by an arc of a radius R.sub.2. Also, the trailing side flank of the female rotor is constituted by a first trailing side flank formed by an arc of the tooth ends of the male rotor having a radius R.sub.5 and a second trailing side flank formed by an arc of a radius R.sub.3 which is smaller than the radius R.sub.2 of the second leading side flank. The configuration of the teeth of the male rotor is materially formed by arcs of the leading and trailing side flanks of the female rotor.

Growing community of inventors

Ibaraki, Japan

Mitsuru Fujiwara