Hitachi, Ltd.

Hitachi Koki Co., Ltd.

Hitachi Powdered Metals Co., Ltd.

Sumihisa Kotani

Kazutaka Suefuji

Akira Murayama

Naoshi Uchikawa

Kenji Tojo

Masao Shiibayashi

Takao Mizuno

Takahiro Tamura

Tetsuya Arata

Hiroaki Kuno

Yoshikatsu Tomita

Kazue Takahashi

Isao Nakajima

Kensaku Oguni

Kei Ishii

Hideo Shikata

Kenji Okuna

Michihiro Watanabe

Tadayuki Tsutsui

Koji Tagusari

Toru Hayama

The present invention relates to a method for producing, without quench-hardening process, a ferrous sintered alloy having satisfactory strength which is equal to that of the conventional ferrous sintered quenched material, and the method comprises the steps of: preparing a powder mixture by adding, in weight ratios, 1 to 2% of copper powder, 1 to 3% of Ni powder, and graphite to a ferrous alloy powder consisting of 3 to 5% of Ni, 0.4 to 0.7% of Mo, and the remainder Fe, the quantity of said graphite being determined such that the C-content after sintering is 0.2 to 0.7%; compacting said powder mixture in a tool to form a green compact; sintering said green compact in a non-oxidizing atmosphere at a temperature in the range of 1130.degree. to 1230.degree. C.; and cooling the sintered product in the sintering furnace at a rate of 5.degree. C./min. to 20.degree. C./min.

Method for producing ferrous sintered alloy having quenched structure

A scroll-type fluid machine having a stationary scroll member and an orbiting scroll member each of which includes a disc-like end plate and a spiral wrap extending axially from one side of the end plate, with the wraps of the scroll members meshing with each other to define therebetween closed compression chambers. The orbiting scroll member is disposed between the end plate of the stationary scroll member and a frame of the machine with a back clearance between the other side of the end plate of the orbiting scroll member side thereof and the opposing surface of the frame. The orbiting scroll member is driven to make an orbiting movement with respect to the stationary scroll member so that the compression chambers are progressively moved towards the center of the scroll members while decreasing their volumes, to thereby suck a fluid through a suction port in the stationary scroll member and compress the same to discharge the compressed fluid through a discharge port formed in the stationary scroll member. The radial clearance between the wraps of both scroll members is selected to meet a specific condition so as to avoid mutual contact between the wraps of the scroll members even when the orbiting scroll member is inclined with respect to the horizontal plane.

Scroll-type fluid machine with radial clearance between wraps

Disclosed is a scroll-type fluid machine which has an orbiting scroll member and a stationary scroll member each having an end plate and a spiral wrap protruding upright therefrom. The scroll members are assembled together such that their wraps mesh with each other to form therebetween closed chambers of volumes which are progressively decreased as the chambers are moved toward the centers of the scroll members as a result of an orbital movement of the orbiting scroll member with respect to the stationary scroll member. The machine is suitable for use as a refrigerant compressor in a refrigeration system. A fluid check valve is disposed in the refrigerant gas suction passage connected to the suction side of the machine, so as to prevent any reversing of the orbiting scroll member. A passage is formed to provide a communication between a suction chamber defined by the scroll members and another closed chamber. A relief valve is disposed in this communication passage so as to relief any abnormal high pressure from the suction chamber.

Scroll device with suction chamber pressure relief

A scroll-type fluid machine having an orbiting scroll member and a stationary scroll member each having an end plate and a spiral wrap of at least two turns protruding upright from one of the sides of the end plates. The orbiting scroll member has a back pressure chamber formed on the back side thereof and communicating with the compression spaces of the fluid machine through pressure equalizing ports formed in the orbiting scroll member, so that the pressure of the fluid under compression is introduced to the back pressure chamber to produce an axial thrusting force for pressing the orbiting scroll member towards the stationary scroll member. The positions of the pressure equalizing ports in terms of the wrap angle .lambda. of the wraps are selected to meet the following condition:

Scroll-type fluid machine with back pressure chamber biasing an orbiting

A refrigeration system including a scroll type compressor having a stationary scroll member, an orbiting scroll member, a discharge port formed in the central portion of the end plate of the fixed scroll member, a suction port formed in a peripheral portion of the fixed scroll member, and at least one gas injection port formed through the thickness of an end plate of the fixed scroll member in a portion of the end plate near the spiral wrap, at a position spaced from the wall of the spiral wrap by a radial distance less than the thickness of the spiral wrap. A discharge pipe is connected to the discharge port, with a suction pipe being connected to the suction port. A refrigerant circuit is connected between the suction pipe and the discharge pipe of the scroll type compressor and includes a four-way valve, indoor heat exchanger, first pressure reducer, gas-liquid separator, second pressure reducer and an outdoor heat exchanger. A gas injection passage is connected between the gas outlet formed in an upper part of the gas-liquid separator and the gas injection port, so as to permit the refrigerant gas in the upper part of the gas-liquid separator to be additionally supplied into the compression chambers under compression in the scroll type compressor.

Refrigeration system incorporating scroll type compressor

A printing hammer driving apparatus for high-speed printers comprises a lever member acting as a hammer operating part, an armature forming a part of a magnetic circuit, and an electromagnet forming, together with the armature, the magnetic circuit. The lever member has a rotational supporting point at the base end thereof and is made of a light-weight non-magnetic material. The armature is projected in one of the rotational directions of the lever member from the intermediate part of the lever member. The electromagnet has at least one core and an exciting coil wound on the core. A core has a magnetic pole face perpendicular to the direction of attraction of the armature and a magnetic pole face parallel to the direction of attraction of the armature. The magnetic pole face perpendicular to the direction of armature attraction is opposed with a gap to the forward end face of the armature, and the magnetic pole face parallel to the direction of armature attraction is opposed with a gap to the surface of the armatures parallel to the direction of attraction thereof.

Printing hammer driving apparatus

A refrigerating system including a refrigeration circuit and a scroll type compressor provided with two volume control mechanisms to allow the system to selectively perform full load operation and unloaded operation. The scroll type compressor includes two scroll members of known construction meshing with each other to define compression chambers and a suction chamber and is combined with the refrigeration circuit having an outdoor heat exchanger, an expansion valve, an indoor heat exchanger and a four-way change-over valve to provide a heat pump type refrigerating system. The volume control mechanisms each include a pair of bypass apertures in the fixed scroll member communicating with a valve chamber having a valve member slidably mounted therein and normally biased to an open position by a spring. The bypass apertures, of which one communicates with the suction chamber and the other communicates with one of the compression chambers, and the valve chamber constitute a bypass passageway. A pressure introducing pipe opens in the valve chamber. Upward movement of the valve member brings the two bypass apertures in communication with each other through the valve chamber to enable the system to perform a volume control operation. In another application, four volume control mechanisms are located symmetrically and divided into two blocks through a flow passage switching device to assign two mechanisms to one block. By this arrangement, the system is able to perform volume control operation in three stages, or able to operate selectively at maximum load, intermediate load and minimum load.

Refrigerating system using scroll type compressor

Growing community of inventors

Ibaraki, Japan

Sumihisa Kotani