Supercritical cycle and expansion valve used for refrigeration cycle

Abstract

A supercritical cycle comprises an evaporator 41, a compressor 33, a gas cooler 35 and a main valve portion 39 of an expansion valve 37 arranged in that order. An internal heat exchanger 45 is arranged for exchanging heat between the high-pressure side refrigerant flowing toward the main valve portion 39 of the expansion valve 37 from the gas cooler 35 and the low-pressure side refrigerant flowing toward the compressor 33 from the evaporator 41. The expansion valve 37 is formed integrally with a temperature sensing portion 47 for controlling the main valve portion 39, and includes a bypass 51 for supplying the refrigerant to the temperature sensing portion 47 from the upstream side of the internal heat exchanger 45 in which the high-pressure side refrigerant flows and an orifice 53 for supplying the refrigerant from the temperature sensing portion 47 to the refrigerant circuit downstream of the main valve portion 39. The internal heat exchanger are arranged between the devices to facilitate the mounting thereof, while at the same time shortening the piping length.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a supercritical cycle according to a first embodiment of the invention.

FIG. 2A is a sectional view schematically showing a heat exchanger and a pressure control valve in the supercritical cycle shown in FIG. 1, and FIG. 2B a sectional view taken in line A-A in FIG. 2A.

FIG. 3 shows another example of an orifice included in an expansion valve.

FIG. 4 is a diagram showing a supercritical cycle according to a second embodiment of the invention.

FIG. 5 is a sectional view of a pressure control valve and a diagram showing a supercritical cycle according to a third embodiment of the invention.

FIG. 6A shows the low-temperature operation of the pressure control valve shown in FIG. 5.

FIG. 6B shows the middle-temperature operation of the pressure control valve shown in FIG. 5.

FIG. 6C shows the high-temperature operation of the pressure control valve shown in FIG. 5.

FIG. 7 is a diagram showing the temperature and pressure of the various parts in the low-, middle- and high-temperature operations shown in FIGS. 6A, 6B, 6C, respectively.

FIG. 8 is a sectional view showing a pressure control valve and a supercritical cycle according to a fourth embodiment of the invention.

FIG. 9A is a sectional view showing the low-pressure operation of the pressure control valve shown in FIG. 8.

FIG. 9B is a sectional view showing the middle-pressure operation of the pressure control valve shown in FIG. 8.

FIG. 9C is a sectional view showing the high-pressure operation of the pressure control valve shown in FIG. 8.

FIG. 10 is a sectional view showing a pressure control valve and a supercritical cycle according to a fifth embodiment of the invention.

FIG. 11 is a diagram showing the conventional supercritical cycle.

Claims

1. A supercritical cycle comprising an evaporator (41), a compressor (33), a radiator (35) and a main valve body (39) of an expansion valve (37) arranged in that order, wherein the refrigerant is circulated in the same order, the supercritical cycle further comprising: an internal heat exchanger (45) for exchanging heat between the high-pressure side refrigerant flowing toward the main valve portion (39) of the expansion valve (37) from the radiator (35) and the low-pressure side refrigerant flowing toward the compressor (33) from the evaporator (41);a bypass (51) extending from the high-pressure upstream side or an intermediate part of the internal heat exchanger (45);a temperature sensing portion (47) for controlling the main valve portion (39);a temperature sensing path (5) for supplying the refrigerant from the bypass (51) to the temperature sensing portion (47); anda refrigerant return path (53) for supplying the refrigerant from the temperature sensing portion (47) to the refrigerant path downstream of the main valve portion (39).

2. The supercritical cycle according to claim 1, wherein the refrigerant return path (53), the main valve portion (39) and the temperature sensing portion (47) are formed integrally to constitute the expansion valve (37).

3. The supercritical cycle according to claim 2, wherein the refrigerant return path (53) is formed in the body (49) of the expansion valve (37).

4. The supercritical cycle according to claim 1, wherein the body (49) of the expansion valve (37) is formed with a through hole (68) passing through the body (49) from the temperature sensing portion (47) to the main valve portion (39), andwherein a valve rod (69) reaching the main valve portion (39) from the temperature sensing portion (47) is slidably inserted in the through hole (68), and the valve rod (69) is formed with an orifice (53a) reaching the main valve portion (39) from the temperature sensing portion (47).

5. The supercritical cycle according to claim 1, wherein the bypass (51) is assembled integrally with the internal heat exchanger (45).

6. The supercritical cycle according to claim 5, wherein the bypass (51) branches from a connector (88) on the high-pressure side of the internal heat exchanger (45).

7. The supercritical cycle according to claim 5, wherein the upstream end of the bypass (51) and the upstream end of the internal heat exchanger (45) are connected to the radiator (35) by a single coupler (87), andwherein the downstream end of the bypass (51) and the downstream end of the internal heat exchanger (45) are connected to the temperature sensing path (5) and the expansion valve (37), respectively, by a single coupler (98).

8. The supercritical cycle according to claim 1, comprising a mixing portion (103) formed at the intermediate part of the bypass (51) and a mixing path (107) extending to the mixing portion (103) from the intermediate part of a path formed from the intermediate part on the high-pressure side or from the downstream side of the internal heat exchanger (45) to the main valve portion (39), wherein the mixing portion (103) mixes the refrigerant from the bypass (51) with the refrigerant from the mixing path (107) at an arbitrary ratio and supplies the mixture to the temperature sensing path (5).

9. The supercritical cycle according to claim 8, wherein the refrigerant from the bypass (51) and the refrigerant from the mixing path (107) are mixed and adjusted by the mixing portion (103) at a ratio in the range of 0 to 100% based on the temperature of at least one of the refrigerant flowing from the bypass (51) into the mixing portion (103) and the refrigerant flowing from the mixing path (107) into the mixing portion (103).

10. The supercritical cycle according to claim 8, wherein the refrigerant from the bypass (51) and the refrigerant from the mixing path (107) are mixed and adjusted by the mixing portion (103) at a ratio in the range of 0 to 100% based on the pressure of the bypass (51) or the mixing path (107).

11. The supercritical cycle according to claim 8, wherein the refrigerant from the bypass (51) and the refrigerant from the mixing path (107) are mixed and adjusted in such a manner that the temperature of the refrigerant flowing into the temperature sensing portion (47) may not exceed a predetermined temperature.

12. The supercritical cycle according to claim 8, wherein the mixing portion (103) is formed integrally with the expansion valve (37) or the internal heat exchanger (45).

13. The supercritical cycle according to claim 1, wherein the internal heat exchanger (45) constitutes a main internal heat exchanger (45) and the bypass (51) constitutes a first bypass (51), the super critical cycle further comprising: a second bypass (153) arranged in parallel to the low-pressure side of the main internal heat exchanger (45) and through which the low-pressure side refrigerant flows; anda subsidiary heat exchanger (155) for reducing the temperature of the refrigerant flowing into the temperature sensing portion (47) through the first bypass (51) by exchanging heat between the refrigerant flowing in the second bypass (153) and the refrigerant flowing in the first bypass (51).

14. An expansion valve comprising: a main valve portion (39) for expanding the refrigerant flowing from the high to low pressure side of the refrigeration cycle;a temperature sensing portion (47) for controlling the main valve portion (39);a temperature sensing path (5) for introducing the refrigerant into the temperature sensing portion (47) from the high-pressure upstream side or the intermediate part of the internal heat exchanger (45) for exchanging heat between the refrigerant downstream of the radiator and the refrigerant upstream of the compressor in the refrigeration cycle; anda refrigerant return path (53) for supplying the refrigerant from the temperature sensing portion (47) to the refrigerant path downstream of the main valve portion (39).