Expansion valve

Abstract

To provide an expansion valve which is capable of preventing the temperature of refrigerant compressed by a compressor from becoming too high, when a refrigeration load on a refrigeration cycle using an internal heat exchanger is high. A thermostatic expansion valve is applied to a refrigeration cycle provided with an internal heat exchanger that performs heat exchange between high-temperature refrigerant flowing from a condenser to the expansion valve and low-temperature refrigerant flowing from an evaporator to a compressor via the expansion valve. The expansion valve comprises a bypass passage or for causing refrigerant in a high-pressure refrigerant inlet or a low-pressure refrigerant outlet to flow to the downstream side of a temperature-sensing section, such that moist refrigerant is mixed with refrigerant whose degree of superheat is controlled by the expansion valve. This lowers the temperature of refrigerant that is drawn into the compressor when refrigeration load is high is lowered, to thereby prevent the temperature of refrigerant compressed by the compressor from becoming too high.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system diagram of a refrigeration cycle to which is applied an expansion valve according to the present invention.

FIG. 2 is a central longitudinal cross-sectional view of the construction of an expansion valve according to a first embodiment.

FIG. 3 is a central longitudinal cross-sectional view of the construction of an expansion valve according to a second embodiment.

FIG. 4 is a central longitudinal cross-sectional view of the construction of an expansion valve according to a third embodiment.

FIG. 5 is a central longitudinal cross-sectional view of the construction of an expansion valve according to a fourth embodiment.

FIG. 6 is a central longitudinal cross-sectional view of the construction of an expansion valve according to a fifth embodiment.

FIG. 7 is a central longitudinal cross-sectional view of the construction of an expansion valve according to a sixth embodiment.

FIG. 8 is a central longitudinal cross-sectional view of the construction of an expansion valve according to a seventh embodiment.

Claims

1. A thermostatic expansion valve that is configured to control a flow rate of refrigerant to be delivered to an evaporator by causing a temperature-sensing section to sense a temperature and a pressure of refrigerant having flowed out from an evaporator, comprising: a bypass passage formed between a high-pressure refrigerant inlet to which high-pressure refrigerant is supplied or a low-pressure refrigerant outlet from which low-pressure refrigerant is delivered to the evaporator, and a refrigerant passage that passes the refrigerant having flowed out from the evaporator, for passing high-pressure liquid refrigerant or low-pressure gas-liquid mixed refrigerant to a downstream side of said temperature-sensing section.

2. The expansion valve according to claim 1, wherein said bypass passage is an orifice formed through a body between said high-pressure refrigerant inlet and said refrigerant passage.

3. The expansion valve according to claim 1, wherein said bypass passage has a differential pressure control valve that opens when a differential pressure thereacross becomes not lower than a predetermined value, in a passage formed through a body between said high-pressure refrigerant inlet and said refrigerant passage.

4. The expansion valve according to claim 1, wherein said bypass passage is an orifice formed through a body between said low-pressure refrigerant outlet and said refrigerant passage.

5. The expansion valve according to claim 1, wherein said bypass passage has a differential pressure control valve that opens when a differential pressure thereacross becomes not lower than a predetermined value, in a passage formed through a body between said low-pressure refrigerant outlet and said refrigerant passage.

6. The expansion valve according to claim 1, wherein said bypass passage is a through hole formed through a body such that a shaft is inserted therethrough, said shaft being disposed between said temperature-sensing section and a valve element that controls the flow rate of refrigerant delivered to the evaporator.

7. The expansion valve according to claim 1, wherein said bypass passage has a differential pressure control valve that opens when a differential pressure thereacross becomes not lower than a predetermined value, in a through hole formed through a body such that a shaft is inserted therethrough, said shaft being disposed between said temperature-sensing section and a valve element that controls the flow rate of refrigerant delivered to the evaporator.

8. The expansion valve according to claim 1, which is applied to a refrigeration cycle provided with an internal heat exchanger that performs heat exchange between refrigerant having flowed out from a condenser and refrigerant being drawn into a compressor.