Hitachi, Ltd.

Kimio Nagata

Shigekazu Nozawa

Takao Mizuno

Minetoshi Izushi

Naomi Hagita

Atushi Amata

In a scroll compressor having a stationary scroll and a revolving scroll, and a refrigerator incorporating this scroll compressor, the stationary scroll has a gas suction hole formed in its radially outer portion, a gas discharge hole formed in its central portion, and gas injection holes and a liquid injection hole formed between the suction and discharge holes. The gas injection holes are formed in a radially outer portion of the stationary scroll, and the liquid injection hole are formed in a central portion of the stationary scroll. The refrigerator incorporates the scroll compressor, a condenser, decompressors and an evaporator to form a refrigerating circuit. The liquid injection hole of the scroll compressor is directly connected by piping to the outlet of the condenser, and the gas injection holes are connected by piping to the outlet of the condenser through one of the decompressors. Even though the compressor is a single-stage compressor having one compression unit and one electric motor unit, the reduction in the volumetric efficiency can be limited and the power necessary for compression during practical use is substantially the same as the power for the two-stage compression type. Consequently, the compressor of the invention has substantially the same compressor efficiency as the conventional two-stage compressor at evaporation temperatures of -45.degree. to -70.degree. C.

Scroll compressor and scroll-type refrigerator

A screw compressor in which a pair of screw rotors supported by bearings and accommodated in a casing act to compress a gas and in which a slide valve disposed between an inner wall of the casing and the pair of screw rotors is capable of moving axially while maintaining a small gap between itself and the outer peripheries of the screw rotors, the rate of gas flow bypassed to an inlet port during compression being regulated by axially moving the slide valve. The screw compressor has: a side cover in which bearing for supporting the pair of screw rotors on the discharge side and a slide valve driving hydraulic means are incorporated and which is disposed on the discharge side of the screw rotors; a discharge axial port formed in the side cover; and at least one projection continuous with an opening edge of the discharge axial port and in contact with a semi-circular surface of the slide valve facing in the radial direction thereof, the projection acting to limit the radial movement of the slide valve while the slide valve is moving in contact with the top end of the projection.

Screw compressor with slide valve movement preventing structure

A refrigerant gas injection system for a refrigeration cycle of the type having a screw compressor provided with a slide valve for controlling the compression capacity of the screw compressor, an economizer disposed in a passage for refrigerant liquid and adapted for subcooling the refrigerant liquid by the refrigerant of a reduced pressure, and a refrigerant gas injection line through which the refrigerant gas generated in the economizer is injected into the compression chamber of the screw compressor in its compression phase. The refrigerant gas injection system has a gas injection controller adapted to enable the injection of the refrigerant gas when the screw compressor is operating at full (100%) capacity or load level and to prevent the injection of the refrigerant gas when the screw compressor is operating in unloaded state.

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Shimizu, Japan

Kimio Nagata