Abstract: An overheating prevention method for a fixed displacement type compressor having an overheating prevention device for introducing a part of high pressure liquefied coolant, liquefied in a compressor of a refrigeration cycle, into a compression chamber maintained under a compression stroke of the compressor through a connecting pipe, and for controlling a flow rate of the liquefied coolant flowing through the communication pipe to thereby cool the compressor. The connecting pipe is communicated with the compressor so that an average pressure within the compressor is reduced relative to a condensed pressure under a minimum operational pressure ratio condition at which the introduction of the liquefied coolant is required for cooling the compressor, within an operational pressure range in which the condensed pressure and evaporation pressure are respectively variable.

Abstract: A refrigeration cycle apparatus wherein a positive displacement type compressor is used as a cooling medium compressor, and part of a high-pressure liquid cooling medium liquefied in a condenser of a refrigeration cycle is introduced into a compression chamber of the compressor during a compression stroke thereof via first and second connecting pipes connected to the compressor, thereby preventing the overheating of the compressor. The position of connection of the first connecting pipe to the compressor is set to such a position of the compression chamber that when an operating pressure ratio requiring the cooling of the compressor is minimum, the pressure within the compression chamber of the compressor during the compression stroke can be below a condensation pressure at the operating pressure ratio.

Abstract: 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.