WO2012108112A1

WO2012108112A1 - Refrigeration cycle device

Info

Publication number: WO2012108112A1
Application number: PCT/JP2011/080271
Authority: WO
Inventors: 智貴佐々木; 佐藤　博
Original assignee: サンデン株式会社
Priority date: 2011-02-08
Filing date: 2011-12-27
Publication date: 2012-08-16
Also published as: JP2012163281A

Abstract

Provided is a refrigeration cycle device with which the amount of heat exchanged by an internal heat exchanger can be increased compared to the prior art while maintaining high operating efficiency and operating ability. This refrigeration cycle device has a dual-tube type internal heat exchanger, comprising an inner tube (32) through which a cooling medium that circulates within the refrigeration cycle flows from the outlet of an evaporator to the inlet of a compressor, and an outer tube (31) through which the cooling medium flows from the outlet of a condenser to the inlet of the evaporator. A bypass passage (B1), which causes a portion of the high-temperature, high-pressure liquid-phase cooling medium flowing in the outside space (S1) between the outer tube (31) and the inner tube (32) to bypass into the inside space (S2) within the inner tube (32), is formed between the tube walls of a gas-phase cooling medium inflow pipe (8) and the inner tube (32), which overlap in the axial direction when the small-diameter part (8A) at the end of the gas-phase cooling medium inflow pipe (8) is fitted into an end of the inner tube (32).

Description

Refrigeration cycle equipment

The present invention relates to a refrigeration cycle apparatus having an internal heat exchanger used in a vapor compression refrigeration cycle of a vehicle air conditioner.

2. Description of the Related Art A heat pump cycle that performs an air conditioning operation using a refrigerant such as carbon dioxide is known that has an internal heat exchanger as described in Patent Document 1. In such a cycle device, heat exchange is performed between a high-temperature and high-pressure liquid-phase refrigerant and a low-temperature and low-pressure gas-phase refrigerant, thereby reducing the specific enthalpy of the evaporator inlet refrigerant and increasing the refrigeration effect. Improvements in cycle efficiency and capacity have been made.

Japanese Patent Gazette: Japanese Patent No. 4239256

In an internal heat exchanger used in a conventional refrigeration cycle device, if the amount of heat exchange is excessively increased, the suction superheat degree of the compressor becomes abnormally high, which may adversely affect the durability of the compressor and the discharge hose. there were. In order to avoid such adverse effects, when operating the internal heat exchanger, it is necessary to set the upper limit of the heat exchange amount to such an extent that the suction superheat degree of the compressor can be suppressed within a predetermined range. Efficiency and driving ability could not be increased sufficiently.

An object of the present invention is to provide a refrigeration cycle apparatus capable of increasing the operating efficiency and operating capacity as much as possible by increasing the amount of heat exchange in the internal heat exchanger while suppressing the suction superheat degree of the compressor small. And

In order to solve the above problems, a refrigeration cycle apparatus according to the present invention includes:
In the refrigeration cycle, one of the low-temperature and low-pressure refrigerant flowing from the evaporator outlet to the compressor inlet and the high-temperature and high-pressure refrigerant flowing from the condenser outlet to the evaporator inlet is circulated in the inner space of the inner pipe, and the other is While arranging a double pipe type internal heat exchanger circulated in the space between the inner pipe and the outer pipe,
A portion of the inner tube overlaps the tube walls in the axial direction, and an inner space in the inner tube and an outer space between the inner tube and the outer tube are arranged between the overlapped tube walls. A bypass passage that is communicated with the low-temperature and low-pressure refrigerant flows into a space in which the low-temperature and low-pressure refrigerant flows while a part of the high-temperature and high-pressure refrigerant is decompressed and expanded through the bypass passage. It was set as the structure to do.

In such a refrigeration cycle apparatus of the present invention, in the internal heat exchanger, a part of the high-temperature and high-pressure side liquid-phase refrigerant after passing through the condenser is decompressed and expanded via the bypass passage, and the two-phase refrigerant and And flows into the space in the pipe through which the low-temperature and low-pressure refrigerant flows.

As a result, the two-phase refrigerant is added to the low-temperature and low-pressure gas-phase refrigerant after passing through the evaporator, and the high-temperature and high-pressure refrigerant is more effectively cooled by the latent heat of vaporization of the two-phase refrigerant, thereby increasing the amount of heat exchange in the evaporator. can do.

On the other hand, the temperature rise of the gas-phase refrigerant is also suppressed by the high cooling function by the two-phase refrigerant, the degree of superheat at the evaporator outlet and the compressor inlet can be reduced, the performance deterioration of the compressor can be suppressed, and the suction refrigerant density To increase driving efficiency.

In addition, by bypassing a part of the high-temperature and high-pressure liquid phase refrigerant, the refrigerant flow rate passing through the evaporator can be reduced, pressure loss of the refrigerant in the evaporator can be suppressed, and the refrigerating capacity and cycle efficiency can be improved. It becomes.

Furthermore, the pressure loss due to the outflow can be suppressed by the configuration in which a part of the high-temperature and high-pressure side refrigerant flows out in parallel with the flow direction of the low-temperature and low-pressure side refrigerant. Further, by appropriately adjusting the bypass flow rate and the outflow speed of the high-temperature and high-pressure side refrigerant, it is possible to provide an ejector effect. In this case, one of the power sources for sucking and conveying the low-temperature and low-pressure side refrigerant to the compressor. And contributes to the power saving of the refrigeration cycle.

1 is a schematic view of a refrigeration cycle apparatus according to an embodiment of the present invention. It is a perspective view which shows the internal heat exchanger used in the refrigeration cycle apparatus of FIG. Sectional drawing which shows 1st Embodiment of the internal structure of the bypass channel periphery part in the said internal heat exchanger [(A) is AA arrow sectional drawing of (B), (B) is a longitudinal cross-sectional view, (C ) Is a front view of a double tube]. FIG. 8A is a cross-sectional view taken along the line AA of FIG. 8B, and FIG. 5B is a vertical cross-sectional view showing a second embodiment of the internal structure. FIG. 9B is a cross-sectional view taken along the line AA of (B), and FIG. (B) is a vertical cross-sectional view showing a third embodiment of the internal structure. The figure which similarly shows 4th Embodiment of an internal structure [(A) is AA arrow sectional drawing of (B), (B) is a longitudinal cross-sectional view, (C) is a front view of a double pipe.] is there. FIG. 9A is a cross-sectional view taken along the line AA of FIG. 5B, and FIG. 5B is a vertical cross-sectional view showing a fifth embodiment of the internal structure. FIG. 9B is a cross-sectional view taken along the line AA of (B), and (B) is a vertical cross-sectional view, similarly showing a sixth embodiment of the internal structure. It is a longitudinal cross-sectional view which similarly shows 7th Embodiment (A) and 8th Embodiment (B) of an internal structure. It is a diagram which shows the refrigerating cycle characteristic of the refrigerating cycle apparatus which concerns on this invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic view of a refrigeration cycle apparatus 1 according to an embodiment of the present invention. The refrigerant circulates in the system, and the high-temperature and high-pressure liquid-phase refrigerant that has flowed out of the condenser 2 is outside of the annular shape between the outer pipe 31 and the inner pipe 32 of the double-tube internal heat exchanger 3. The refrigerant flows through the space and mainly flows into the evaporator 4 through the expansion valve 10, but a part of the refrigerant is decompressed and expanded via the bypass passage B formed in the inner pipe 32 and bypasses the evaporator 4 to bypass the inner pipe 32. Flows in.

The refrigerant evaporated in the evaporator 4 flows out from the evaporator 4, then flows into the inner pipe 32 of the internal heat exchanger 3, merges with the bypassed refrigerant, and then flows into the compressor 5.
The refrigerant compressed in the compressor 5 flows into the condenser 2 and is condensed.

FIG. 2 is a perspective view showing a double-pipe internal heat exchanger 3 used in the refrigeration cycle apparatus 1 of FIG. A liquid phase refrigerant inflow pipe 6 that causes the liquid phase refrigerant from the condenser 2 to flow into the outer pipe 31 in the double pipe 30, and a liquid phase refrigerant that causes the liquid layer refrigerant after heat exchange in the outer pipe 31 to flow out to the expansion valve 10. The outflow pipe 7, the gas phase refrigerant inflow pipe 8 that causes the gas phase refrigerant from the evaporator 4 to flow into the inner pipe 32, and the gas phase refrigerant outflow that causes the gas-phase refrigerant after the heat exchange in the inner pipe 32 to flow out to the compressor 5. A tube 9 is connected.

FIG. 3 is a cross-sectional view showing a first embodiment of the internal structure around the bypass passage in the internal heat exchanger 3.
The outer pipe 31 and the inner pipe 32 are integrally formed via ribs arranged in the radial direction, and the end of the double pipe 30 on the outer peripheral wall of the open end portion on the gas phase refrigerant inflow side on the liquid phase refrigerant outflow side. A cap 33 is inserted and fixed. The end cap 33 has an end portion of the gas-phase refrigerant inflow pipe 8 fixed through the end wall, and an end portion of the liquid-phase refrigerant outflow pipe 7 fixed through the peripheral wall. The gas-phase refrigerant inflow pipe 8 constitutes a part of the inner pipe inside the internal heat exchanger 3.

At the opening end of the double pipe 30, the inner peripheral surface of the end of the inner pipe 32 is cut into a conical surface constricted inward, and the conical surface is further divided by 3 at equal intervals in the circumferential direction (every 120 degrees). Engagement surfaces 32a are formed leaving portions, and a communication groove 32b is formed by cutting a predetermined amount in the axial direction between the engagement surfaces 32a.

On the other hand, the gas-phase refrigerant inflow pipe 8 has a small-diameter portion 8A having an outer diameter that is a predetermined amount smaller than the inner diameter of the inner pipe 32 at the end connected to the end of the inner pipe 32 in the internal heat exchanger 3. A portion connecting the small diameter portion 8A and the large diameter portion 8B having the same inner and outer diameter as the inner tube 32 is formed in a conical portion 8C having the same cone angle as the engagement surface 32a.

The outer peripheral surface of the conical portion 8C of the gas-phase refrigerant inflow pipe 8 is abutted and joined to the engagement surface 32a of the inner pipe 32, whereby the axes of the gas-phase refrigerant inflow pipe 8 and the inner pipe 32 coincide with each other. An annular gap 11 is formed between the inner peripheral surface of the end portion of the pipe 32 and the outer peripheral surface of the end portion of the small diameter portion 8A of the gas-phase refrigerant inflow tube 8.

The communication groove 32b and the annular gap 11 communicate the annular outer space S1 between the outer tube 31 through which the high-temperature and high-pressure refrigerant flows and the inner space S2 in the inner tube 32. A bypass passage B1 is formed.

Next, the operation of the refrigeration cycle apparatus including the internal heat exchanger 3 in which the bypass passage B1 is formed will be described.
The high-temperature and high-pressure liquid-phase refrigerant flowing in the outer space S1 exchanges heat with the low-temperature and low-pressure gas-phase refrigerant flowing in the inner space S2 via the inner wall surface of the inner tube 32. On the other hand, a part of the liquid refrigerant is bypassed to the inner space S <b> 2 in the inner pipe 32 via the bypass passage B <b> 1 including the communication groove 32 b and the annular gap 11. Here, the bypass passage B1 is formed so that a flow resistance within a predetermined range is generated in the refrigerant flow passing therethrough, whereby a part of the high-temperature and high-pressure refrigerant is decompressed and expanded into a low-temperature and low-pressure two-phase refrigerant. It is bypassed while being converted, and functions to join the low-temperature and low-pressure gas-phase refrigerant after passing through the evaporator 4. Cycle efficiency can be improved by bypassing and joining the refrigerant in such a configuration and using the latent heat of vaporization of the bypassed refrigerant for cooling the high-temperature and high-pressure refrigerant (see FIG. 10). Further, by increasing the cooling amount of the high-temperature and high-pressure refrigerant, it is possible to keep the dryness of the refrigerant at the inlet of the evaporator 4 low, thereby further improving the refrigeration efficiency and the cycle efficiency.

More specifically, since a part of the refrigerant in the outer space S1 bypasses the evaporator 4 and flows into the inner space S2, the cooling amount due to heat exchange with the outside air in the evaporator 4 decreases by the bypass amount. However, by cooling the high-temperature and high-pressure refrigerant in the outer space S1 with high efficiency by the two-phase refrigerant having the latent heat of evaporation bypassed in the internal heat exchanger 3, a cooling amount equivalent to or greater than the reduced amount is recovered. it can. Further, the refrigerating capacity and the cycle efficiency can be improved by the amount that the pressure loss due to the bypass refrigerant passing through the evaporator can be reduced.

Further, since the amount of cooling of the high-temperature and high-pressure refrigerant is increased using the latent heat of vaporization of the bypass refrigerant, the temperature rise due to heat exchange between the gas-phase refrigerant circulating in the inner space S2 and the high-temperature and high-pressure refrigerant can be suppressed. As a result, the increase in the degree of suction superheat at the inlet of the compressor 5 can be suppressed to suppress a decrease in the durability of the compressor 5, the discharge hose, etc., and the decrease in the suction refrigerant density can be suppressed to increase the operating efficiency. it can. In other words, the shape of the bypass passage B1 (passage cross-sectional area, passage length, etc.) is set so as to reduce the suction superheat degree at the compressor inlet to near zero (see FIG. 10). For example, the bypassed high-temperature / high-pressure refrigerant flow rate is set to 5 to 35% of the high-temperature / high-pressure refrigerant flow rate upstream of the bypass passage.

Incidentally, if only the high-temperature and high-pressure refrigerant is to be bypassed in the internal heat exchanger 3, it is only necessary to form a hole that penetrates the tube wall of the inner tube 32. Incidentally, in Japanese Patent No. 2998582, although the refrigeration cycle is different from that of the present invention, a part of the liquid-phase refrigerant flowing through the outer pipe passes through the inner pipe wall in the inner and outer double pipe heat exchanger. Is bypassed through a hole to make (this is not a heat exchanger that cools the liquid-phase refrigerant from the condenser with the gas-phase refrigerant from the evaporator, and the operation and effect of the present invention cannot be obtained) . However, when the through-hole is simply formed, the outflow direction of the bypass refrigerant intersects with the flow direction of the gas-phase refrigerant flowing in the inner space S2 at a right angle or a large angle to cause turbulence, and the pressure loss increases and is sufficient. However, there is a concern that the cycle efficiency cannot be increased.

On the other hand, in the bypass passage B1 according to the present invention, since the bypass refrigerant flows out in the same direction as the flow direction of the gas-phase refrigerant in the inner space S2, turbulence when the bypass refrigerant flows out can be suppressed, and pressure loss And the refrigerating capacity and cycle efficiency can be sufficiently increased. In particular, in the present embodiment, since the refrigerant can be made to flow out uniformly from the annular gap 11 over the entire circumference, the disturbance suppressing function is enhanced.

Furthermore, depending on the setting of the cross-sectional area of the bypass passage and the bypass flow rate, the bypass refrigerant flowing out in the same direction can exert an ejector effect that assists the flow of the gas-phase refrigerant. When the ejector effect is exhibited, the driving energy of the compressor can be reduced, and the refrigerating capacity and cycle efficiency can be further increased.

The bypass passage B1 is preferably formed only on the upstream side of the inner pipe 32. Specifically, the outer pipe 31 is formed in a range (3D) that is three times as long as the outer diameter (D) of the outer pipe 31 from the end surface of the liquid refrigerant outlet side toward the downstream side of the inner pipe 32. It is preferred that By forming the bypass passage B1 at such a position, an effective heat exchange area on the tube wall surface of the inner tube 32 can be sufficiently secured, and heat exchange of the refrigerant can be performed efficiently.

In addition, since the bypass passage B1 is formed between the inner pipe (the inner pipe 32 and the gas-phase refrigerant inflow pipe 8) divided inside the internal heat exchanger 3, processing is easy and cost as described below. Reduction can be achieved.

For example, in the conventional structure in which the liquid refrigerant in the outer pipe is not bypassed to the inner pipe, the inner pipe of the double pipe protrudes from the end face of the outer pipe, and further passes through the end wall of the end cap, so that the external gas-phase refrigerant inflow pipe It becomes a structure to connect with. Moreover, when providing a bypass hole which penetrates a pipe wall in an inner pipe like patent 2985882, it becomes a structure which forms a bypass hole in the inner pipe which protruded from the end surface of the outer pipe. However, in this structure, it is necessary to cut the outer tube and the inner tube at different end faces, and the junction between the liquid-phase refrigerant inflow tube, the outer tube, and the protruding inner tube is welded to the end cap. In addition, it is necessary to weld the joint between the protruding inner pipe and the gas-phase refrigerant outflow pipe. In addition, in the structure which connects the inner pipe which formed the bypass hole which penetrates a pipe wall previously, and the outer pipe, and forms a double pipe, processing of a double pipe becomes further troublesome.

On the other hand, in the present embodiment, the inner tube and the outer tube of the double tube may be cut at the same end face, and welding is performed by connecting the liquid phase refrigerant inflow pipe, the outer pipe, and the gas phase refrigerant outflow pipe to the end cap. If it is applied to the joint, the number of welds can be reduced.

FIG. 4 is a cross-sectional view showing a second embodiment of the internal structure around the bypass passage.
In the present embodiment, a plurality of axially extending grooves 32c are arranged in the inner peripheral wall of the inner pipe 31 of the double pipe 30 in the circumferential direction, and the outer peripheral surface of the small-diameter portion 8A of the gas-phase refrigerant inflow pipe 8 is It is joined to the inner peripheral surface of the inner tube 32 formed to have the same diameter as the outer peripheral surface. Further, a size set so that an appropriate amount of bypass refrigerant can flow between the outer peripheral surface of the conical portion 8C between the small diameter portion 8A and the large diameter portion 8B of the gas-phase refrigerant inflow pipe 8 and the open end of the groove 32c. The gap 12 is opened.

In the present embodiment, a bypass passage B2 that connects the outer space S1 and the inner space S2 is formed by the gap 12 and the groove 32c between the outer peripheral surface of the small diameter portion 8A and the inner peripheral surface of the inner tube 32. .

Since the refrigerant is bypassed via the bypass passage B2 and the operation and effect due to this are the same as those in the first embodiment, the description is omitted (the same applies to the following embodiments).
In the present embodiment, the axial centers of the gas-phase refrigerant inflow pipe 8 and the inner pipe 32 are made to coincide with each other with high accuracy only by fitting the small-diameter portion 8A of the gas-phase refrigerant inflow pipe 8 into the inner pipe 32 and joining them. The bypass passage B2 having a uniform passage area in the circumferential direction can be easily formed. The groove 32c on the inner peripheral surface of the inner tube 32 can be easily formed by broaching or the like.

Further, the formation of the groove 32c can increase the heat exchange area and increase the heat exchange capacity of the internal heat exchanger 3. In other words, when the groove 32c is formed in advance for increasing the heat exchange capability, the bypass passage B2 can be easily formed using this groove.

FIG. 5 is a cross-sectional view showing a third embodiment of the internal structure around the bypass passage.
In the present embodiment, a plurality of axially extending grooves 8a are provided in the circumferential direction on the outer peripheral surface of the small diameter portion 8A of the gas-phase refrigerant inflow pipe 8, and the outer peripheral surface of the small diameter portion 8A is the inner peripheral surface of the inner tube 32. It is made to join. Further, a gap 13 having a size set so that an appropriate amount of the bypass refrigerant can flow is opened between the outer peripheral surface of the conical portion 8C and the end surface of the inner tube 32.

In the present embodiment, a bypass passage B3 that connects the outer space S1 and the inner space S2 is formed by the gap 13 and the groove 8a.
In the present embodiment, similarly to the second embodiment, the small-diameter portion 8A of the gas-phase refrigerant inflow pipe 8 is simply fitted into the inner pipe 32 and joined, and the gas-phase refrigerant inflow pipe 8 and the inner pipe 32 are connected. The shaft centers can be made to coincide with each other with high accuracy, and the bypass passage B3 having a uniform passage area in the circumferential direction can be easily formed. The groove 8a of the small diameter portion 8A can be easily formed by drawing or the like.

The aspect which replaced the refrigerant | coolant which flows through the inside of an inner pipe and an outer pipe | tube is also employable for this invention.
6 to 8, the low-temperature and low-pressure gas-phase refrigerant is circulated in the outer space S1 between the outer tube 31 and the inner tube 32, and the high-temperature and high-pressure liquid-phase refrigerant is circulated in the inner space S2 in the inner tube 32. It is.

In FIG. 6, an end cap 34 fixed to the outer peripheral wall of the open end portion on the gas phase refrigerant inflow side on the liquid phase refrigerant outflow side of the double pipe 30 passes through the end wall of the liquid phase refrigerant outflow pipe 7. The end is fixed, and the end of the gas-phase refrigerant inflow pipe 8 is fixed through the peripheral wall. The liquid phase refrigerant outflow pipe 7 constitutes a part of the inner pipe 32 inside the internal heat exchanger 3.

A bypass passage B4 that bypasses the liquid-phase refrigerant flowing in the inner space S2 to the outer space S1 is formed as follows.
The fourth embodiment corresponds to the embodiment of FIG. 3, and the outer peripheral surface of the end portion of the inner tube 32 is cut into a conical surface that expands outward, and the conical surface is equally spaced in the circumferential direction. Engagement surfaces 32d are formed at three positions (every 120 degrees), and a predetermined amount of the engagement surfaces 32d are cut in the axial direction to form communication grooves 32e.

On the other hand, the liquid-phase refrigerant outflow pipe 7 has a large-diameter portion whose inner diameter is larger by a predetermined amount than the outer diameter of the inner pipe 32 at the end connected to the end of the inner pipe 32 of the double pipe in the internal heat exchanger 3. A portion connecting the large diameter portion 7A and the small diameter portion 7B having the same inner and outer diameters as the inner tube 32 is formed in a conical portion 7C having the same cone angle as the engagement surface 32d. Yes.

The inner peripheral surface of the conical portion 7C of the liquid-phase refrigerant outflow pipe 7 is abutted against and joined to the engagement surface 32d of the inner pipe 32, so that the axes of the inner pipe 32 and the liquid-phase refrigerant outflow pipe 7 coincide. An annular gap 14 is formed between the outer peripheral surface of the end portion of the inner pipe 32 and the inner peripheral surface of the end portion of the large-diameter portion 7A of the liquid-phase refrigerant outflow tube 7.

The communication groove 32e and the annular gap 14 form a bypass passage B4 that connects the inner space S2 through which the high-temperature and high-pressure refrigerant flows and the outer space S1.
FIG. 7 shows a fifth embodiment corresponding to the embodiment of FIG. 4. A plurality of grooves 32 f extending in the axial direction are arranged in the circumferential direction on the outer peripheral surface of the inner pipe 32, and the end of the liquid-phase refrigerant outflow pipe 7. The inner peripheral surface of the portion and the outer peripheral surface of the inner tube 32 formed to have the same diameter as the inner peripheral surface are joined. Further, a size set so that an appropriate amount of bypass refrigerant can flow between the outer peripheral surface of the conical portion 7C between the large diameter portion 7A and the small diameter portion 7B and the open end of the groove 32f. The gap 15 is opened.

In the present embodiment, a bypass passage B5 that connects the inner space S2 and the outer space S1 is formed by the gap 15 and the groove 32f between the inner peripheral surface of the large-diameter portion 7A and the outer peripheral surface of the inner tube 32. The

In the present embodiment, as in the embodiment of FIG. 4, the shaft of the inner pipe 32 and the liquid-phase refrigerant outflow pipe 7 can be obtained simply by fitting the large-diameter portion 7A of the liquid-phase refrigerant outflow pipe 7 into the inner pipe 32 and joining them. The centers can be made to coincide with each other with high accuracy, and the bypass passage B5 having a uniform passage area in the circumferential direction can be easily formed. Even if the groove 32f does not penetrate in the axial direction, the groove 32f may be formed from the end surface of the large-diameter portion 7A to the depth of the pipe by a predetermined amount so that the bypass refrigerant can flow out in parallel with the flow direction of the gas-phase refrigerant.

FIG. 8 shows a sixth embodiment corresponding to the embodiment of FIG. 5, and a plurality of grooves 7 a extending in the axial direction are arranged in the circumferential direction on the inner peripheral surface of the large-diameter portion 7 </ b> A of the liquid-phase refrigerant outflow pipe 7. Then, the inner peripheral surface of the large diameter portion 7A and the outer peripheral surface of the inner tube 32 are joined. Further, as in the fifth embodiment, a gap 15 having a size set so that an appropriate amount of bypass refrigerant can flow between the inner peripheral surface of the conical 9C and the end surface of the inner tube 32 is opened.

In the present embodiment, the bypass 15 that communicates the inner space S2 and the outer space S1 is formed by the gap 15 and the groove 7a.
Similarly to the embodiment of FIGS. 4 and 7, the present embodiment also includes the inner pipe 32 and the liquid-phase refrigerant outflow pipe 7 simply by fitting the large-diameter portion 7 </ b> A of the liquid-phase refrigerant outflow pipe 7 into the inner pipe 32. The bypass passage 6 having a uniform passage area in the circumferential direction can be easily formed.

In the above embodiment, the bypass passage B is formed by connecting the liquid-phase refrigerant outflow pipe 7 or the gas-phase refrigerant inflow pipe 8 in the internal heat exchanger 3 to the inner pipe 32 as a divided inner pipe. The bypass passage B may be formed without dividing the inner pipe 32.

For example, as shown in FIG. 9A, a plurality of communication holes 32g formed intermittently in the inner space S2 around the inner tube 32 through which the high-temperature and high-pressure liquid refrigerant flows, and the outer periphery of the inner tube 32 A bypass passage B7 is formed by an annular gap inside the pipe member 51 that is fitted and fixed, or a plurality of axially formed grooves 51a formed in this portion.

In FIG. 5B, the outer space S1 is fitted into a plurality of communication holes 32h intermittently formed around the inner pipe 32 through which the high-temperature and high-pressure liquid refrigerant flows, and the inner circumference of the inner pipe 32. A bypass passage B8 is formed by an annular gap outside the pipe member 61 fixed in place or a plurality of axially formed grooves 61a formed in this portion.

The illustrated embodiments are merely examples of the present invention, and the present invention is not limited to those directly described by the described embodiments, and various improvements and modifications made by those skilled in the art within the scope of the claims. Needless to say, it encompasses changes.

The refrigeration cycle apparatus according to the present invention is widely used in a vapor compression refrigeration cycle of a vehicle air conditioner.

DESCRIPTION OF SYMBOLS 1 Refrigeration cycle apparatus 2 Condenser 3 Internal heat exchanger 4 Evaporator 5 Compressor 6 Liquid phase refrigerant inflow pipe 7 Liquid phase refrigerant outflow pipe 7A Large diameter part 7B Small diameter part 7C Conical part 7a Groove 8 Gas phase refrigerant inflow pipe 8A Small diameter Part 8B Large diameter part 8C Conical part 8a Groove 9 Gas phase

refrigerant outflow pipes

11, 12, 13 Gap 30 Double pipe 31 Outer pipe 32

Inner pipe

32a,

32d Engagement surface

32b,

32e Communication groove

32c, 32f

Groove

33, 34

End cap

32g,

32h Communication hole

51a, 61a Annular gap or axially extending grooves B, B1-B8 Bypass passage

Claims

In the refrigeration cycle, one of the low-temperature and low-pressure refrigerant flowing from the evaporator outlet to the compressor inlet and the high-temperature and high-pressure refrigerant flowing from the condenser outlet to the evaporator inlet is circulated in the inner space of the inner pipe, and the other is While arranging a double pipe type internal heat exchanger circulated in the space between the inner pipe and the outer pipe,
A part of the inner tube overlaps the tube walls in the axial direction, and an inner space in the inner tube and an outer space between the inner tube and the outer tube are overlapped with the overlapped tube wall. Forming a bypass passage that communicates with each other, and a part of the high-temperature and high-pressure refrigerant is decompressed and expanded through the bypass passage, and the flow direction of the low-temperature and low-pressure refrigerant is the same as a flow direction of the low-temperature and low-pressure refrigerant A refrigeration cycle apparatus having a structure that flows out in a direction.
The refrigeration cycle apparatus according to claim 1, wherein the inner pipe is divided in the axial direction inside the heat exchanger, and the pipe walls at the ends of the two divided inner pipes are overlapped in the axial direction.
The refrigeration cycle apparatus according to claim 2, wherein the overlap portion includes a plurality of axially extending grooves in at least one of the opposed peripheral walls of the divided two inner pipes in the circumferential direction.
The two divided inner pipes are formed such that the end of one inner pipe is bent and overlaps the end of the other inner pipe in the axial direction, and the pipe diameter is equal except for the overlap portion. The refrigeration cycle apparatus according to claim 2.
2. The refrigeration cycle apparatus according to claim 1, wherein the bypass passage is disposed on a high temperature and high pressure refrigerant outlet side of the internal heat exchanger and on a low temperature and low pressure refrigerant inlet side.
The refrigeration cycle apparatus according to claim 1, wherein a part of the high-temperature high-pressure refrigerant is set to 5 to 35% of a high-temperature high-pressure refrigerant flow rate upstream of the bypass passage.