Expansion valve for refrigerating cycle

Abstract

An expansion valve for a refrigerating cycle, in which the body dimensions and the weight of the whole valve can be reduced and a reduction in cost can be achieved. An expansion valve of the invention comprising a temperature-sensing portion arranged in a refrigerant passage leading to an evaporator from a gas cooler or an internal heat exchanger in a vapor compression type refrigerating cycle and varied in internal pressure according to a refrigerant temperature at an outlet side of the gas cooler or on an outlet side of the internal heat exchanger, a valve member that mechanically interlocks with a change in internal pressure of the temperature-sensing portion to adjust an opening degree of a valve port, and a body that accommodates therein the valve member, and wherein the body is provided with a flow passage, through which a refrigerant reduced in pressure by the valve member is led to the evaporator while a refrigerant temperature at the outlet side of the gas cooler or on the outlet side of the internal heat exchanger is transmitted to the temperature-sensing portion. Also, that density, at which a refrigerant is charged in a temperature-sensing body, is set in the range of about 200 kg / m3 to about 600 kg / m3. Further, a ratio of a temperature-sensing cylinder corresponding portion to the temperature-sensing body is made at least 60%.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an expansion valve for a refrigerating cycle that controls a refrigerant on a radiator outlet side on the basis of a refrigerant temperature at the radiator (gas cooler) outlet side of a vapor-compression-type refrigerating cycle, and is especially suited to a supercritical refrigerating cycle that uses a refrigerant, such as carbon dioxide (CO2) or the like, in a supercritical range. [0003] 2. Description of Related Art [0004] Generally, it is known to use, as a vehicular air conditioning apparatus, a vapor-compression-type refrigerating cycle that circulates CO2 as a refrigerant in a closed circuit comprising a compressor 1, a gas cooler (radiator) 2, an expansion valve 3, an evaporator 4, an accumulator 5, etc. Conventionally, a pressure control valve as disclosed in JP-A-2000-193347 and JP-A-2003-254460 is known as a mechanical type expansion valve used in such a vapor compressio...

AI Technical Summary

Benefits of technology

[0013] The invention has been made in view of the above problems and has as its object to provide an expansion valve for a refrigerating cycle that does not need any casing and any temperature-sensing cylinder, can reduce the body dimensions and the weight of the whole valve and enables a reduction in cost. A further object is to provide an expansion valve for a refrigerating cycle that can decrease the pressure-resistance of a temperature-sensing portion by optimizing control characteristics in the case where an internal heat exchanger is used in combination. A still further object is to provide an expansion valve or a refrigerating cycle comprising an expansion valve which, when used in a supercritical cycle, decreases variation in control pressure and enables miniaturization of an expansion valve member.

Problems solved by technology

However, the pressure control valve of the conventional type involves a problem that the weight is increased to lead to an increase in cost as there is a need for the casing 33 that covers the enclosed space (temperature-sensing portion).

Also, the case where CO2 is used as a refrigerant involves a problem that the theoretical cycle efficiency is low as compared to HFC134a as conventionally used.

However, a refrigerant put in a supercritical state is affected by temperatures of those regions, which are communicated to and other than the temperature-sensing portion, to cause a problem that the internal pressure of the temperature-sensing portion is not determined and control pressure is varied.

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