Piping structure of heat exchanger and manufacturing method for same

Abstract

Provided are a piping structure of a heat exchanger and a manufacturing method for the same, by which it is possible to eliminate complexity of the manufacturing process, suppress thermal deterioration of members in the manufacturing process, and separate a double pipe portion. A space between an outer pipe 3 and a manifold 4A, 4B externally inserted into an inner pipe 2 is sealed by an annular seal material S1. A screw part 4g of the manifold 4A, 4B and a screw part 7c of a connecting body 7A, 7B are screwed together; a flare part 2a, 2b and a tapered cylinder part 6a of a connection inner pipe 6 inserted into the flare part 2a, 2b are pressed from an outer circumferential side by an inner circumferential surface of a tapered through-hole 4c of the manifold 4A, 4B to bring the tapered cylinder part 6a, the flare part 2a, 2b, and the inner circumferential surface of the tapered through-hole 4c to close contact in an integrated manner to seal the space between the manifold 4A, 4B and the inner pipe 2. The manifold 4A, 4B is held between the connecting body 7A, 7B and a longitudinal end of the outer pipe 3 to restrict movement in the longitudinal direction, and pipe bodies 5a, 5b are respectively connected to the manifolds 4A, 4B by brazing.

Description

Heat exchanger piping structure and manufacturing method thereof

[0001] The present invention relates to a piping structure of a heat exchanger and a manufacturing method thereof, and more particularly to a piping structure of a heat exchanger and a manufacturing method thereof that can eliminate the complexity of the manufacturing process, suppress thermal deterioration of components during the manufacturing process, and enable the double pipe portion to be separated.

[0002] Various piping structures for heat exchangers have been proposed (see, for example, Patent Document 1). Patent Document 1 describes a double-pipe structure in which a condenser 320 is disposed around an aluminum alloy pipe 205 between an evaporator 204 and a compressor 201 (see paragraph 0035, FIGS. 1 to 8, etc. of Patent Document 1). In the piping structure described in Patent Document 1, end caps 322 and 323 that close both ends of a main body 321 of the condenser 320 are connected to the pipe 205 by brazing. Furthermore, a refrigerant pipe 330 is connected to the end cap 323 by brazing.

[0003] Conventionally, brazing has been used to improve sealing, but this brazing process requires a significant amount of time. Furthermore, there is a risk of thermal degradation of components heated during the brazing process. Furthermore, because the double-walled pipe section is brazed, it cannot be partially replaced. Therefore, when manufacturing the piping structure of a heat exchanger, there is room for improvement in reducing the number of brazed sections to eliminate the complexity of the manufacturing process, suppressing thermal degradation of components during this manufacturing process, and making the double-walled pipe section separable.

[0004] Japanese Patent Application Publication No. 2021-148374

[0005] The object of the present invention is to provide a piping structure for a heat exchanger and a manufacturing method thereof that can eliminate the complexity of the manufacturing process, suppress thermal deterioration of components during the manufacturing process, and enable the double pipe portion to be separated.

[0006] In order to achieve the above object, the piping structure of the heat exchanger of the present invention comprises an inner pipe and an outer pipe constituting a double pipe structure, a cylindrical manifold fitted onto the inner pipe and installed at both longitudinal ends of the outer pipe, and pipe bodies brazed to each of the manifolds, wherein the longitudinal ends of the outer pipe are sealed by each of the manifolds, a flow path of each of the pipe bodies communicates with an internal space of the brazed manifold, and a flow path between an outer peripheral surface of the inner pipe and an inner peripheral surface of the outer pipe and the internal space of each of the manifolds are sealed. In a piping structure of a heat exchanger in which an outer peripheral region of the inner pipe communicates with the manifold in a space, the structure includes an annular seal for an outer pipe interposed between each of the manifolds and the outer pipe, one connecting inner pipe connected to one longitudinal end of the inner pipe, the other connecting inner pipe connected to the other longitudinal end of the inner pipe, one cylindrical connecting body fitted onto the one connecting inner pipe, and the other cylindrical connecting body fitted onto the other connecting inner pipe, and flared portions are formed at both longitudinal ends of the inner pipe, and the length of each of the connecting inner pipes facing each of the flared portions is The longitudinal end of each manifold is formed into a tapered cylindrical portion that is inserted into the flared portion, and a threaded portion is formed on the outer peripheral surface of the longitudinal end of each manifold, and a tapered through hole extending in the longitudinal direction is formed on the inner peripheral surface, and when the threaded portion of one of the manifolds and the threaded portion of one of the connecting bodies are screwed together, the tapered cylindrical portion inserted into one of the flared portions and its flared portion are pressed from the outer peripheral side by the inner peripheral surface of the tapered through hole of one of the manifolds, and the tapered cylindrical portion, its flared portion, and its tapered through hole are pressed from the outer peripheral side. one of the manifolds is sandwiched between the one of the connecting bodies and one longitudinal end of the outer tube and is installed so that longitudinal movement is restricted, and the threaded portion of the other of the manifolds is threadedly engaged with the threaded portion of the other of the connecting bodies, so that the tapered cylindrical portion inserted into the flared portion of the other of the manifolds and its flared portion are pressed from the outer circumferential side by the inner circumferential surface of the tapered through hole of the other of the manifolds, so that the tapered cylindrical portion, its flared portion, and the inner circumferential surface of the tapered through hole are integrated and closely adhered to each other,The other manifold is sandwiched between the other connecting body and the other longitudinal end of the outer pipe, and is installed so that its longitudinal movement is restricted.

[0007] The method for manufacturing a piping structure of a heat exchanger of the present invention is a method for manufacturing a piping structure of a heat exchanger having a double pipe structure consisting of an inner pipe and an outer pipe, a cylindrical manifold inserted onto the inner pipe and installed at both longitudinal ends of the outer pipe, and pipe bodies brazed to each of the manifolds, by preparing one connecting inner pipe connected to one longitudinal end of the inner pipe, another connecting inner pipe connected to the other longitudinal end of the inner pipe, one cylindrical connecting body inserted onto the one connecting inner pipe, and another cylindrical connecting body inserted onto the other connecting inner pipe; a threaded portion is formed on the outer peripheral surface of a longitudinal end of each of the manifolds, and a tapered through hole extending in the longitudinal direction is formed on the inner peripheral surface; one longitudinal end of each of the connecting inner tubes is formed as a tapered cylindrical portion; one longitudinal end of the inner tube is formed as a flared portion; one of the manifolds is fitted onto the inner tube so that the one flared portion and the inner peripheral surface of the tapered through hole of one of the manifolds are abutted against each other; after fitting the outer tube onto the inner tube, the other manifold is fitted onto the inner tube so that the outer tube is fitted onto each of the manifolds; and a second flared portion is formed at the other longitudinal end of the inner pipe, and the second flared portion is brought into contact with the inner peripheral surface of the tapered through-hole of the other manifold. The threaded portion of one of the manifolds is screwed into the threaded portion of one of the connecting bodies, and the tapered cylindrical portion of one of the connecting inner pipes inserted into the first flared portion and its flared portion are screwed into the first manifold. the tapered cylindrical portion and the flared portion of the other connecting inner pipe are pressed from the outer circumferential side by the inner circumferential surface of the tapered through hole of the hold, the tapered cylindrical portion and the flared portion of the other connecting inner pipe are integrated and tightly attached to each other, one of the manifolds is clamped between the one of the connecting bodies and one longitudinal end of the outer pipe to restrict longitudinal movement, the threaded portion of the other manifold is screwed into the threaded portion of the other connecting body, and the tapered cylindrical portion and the flared portion of the other connecting inner pipe inserted into the other flared portion are pressed from the outer circumferential side by the inner circumferential circle of the tapered through hole of the other manifold,The tapered cylindrical portion, the flared portion, and the inner peripheral surface of the tapered through hole are integrated and tightly attached, the other manifold is sandwiched between the other connecting body and the other longitudinal end of the outer pipe to restrict longitudinal movement, and the flow path between the outer peripheral surface of the inner pipe and the inner peripheral surface of the outer pipe communicates with an outer peripheral region of the inner pipe in the internal spaces of one of the manifolds and the other of the manifolds, the flow path of one of the pipe bodies brazed to one of the manifolds communicates with the internal space of one of the manifolds, and the flow path of the other pipe body brazed to the other of the manifolds communicates with the internal space of the other of the manifolds.

[0008] According to the present invention, each of the manifolds can be installed together with the outer pipe while restricting longitudinal movement using the respective connecting bodies arranged at two locations spaced apart along the longitudinal direction of the inner pipe, and the gap between each of the manifolds and the outer pipe is sealed by the respective annular sealing material for the outer pipe. Furthermore, the gap between each of the manifolds and the inner pipe is sealed by integrating and tightly fitting the tapered tubular portion of each of the connecting inner pipes, the corresponding flared portion of the inner pipe, and the inner circumferential surface of the corresponding tapered through hole of the manifold. Because brazing is required only for connecting each of the manifolds to each of the pipe bodies, the complexity of the manufacturing process of this piping structure can be eliminated. This is advantageous for suppressing thermal degradation of the inner pipe and the outer pipe during the manufacturing process.

[0009] The connecting bodies connected to the respective manifolds can be separated by unscrewing the threaded portions of each other. Accordingly, the double-pipe portion formed by the inner pipe and the outer pipe can be separated from the respective connecting bodies and the respective connecting inner pipes, and this double-pipe portion can be separated from the respective manifolds. Therefore, part of this piping structure can be replaced as needed.

[0010] FIG. 1 is an explanatory diagram illustrating an embodiment of a piping structure for a heat exchanger, as seen from the front. FIG. 2 is an explanatory diagram illustrating the piping structure of FIG. 1, as seen from the vertical cross section. FIG. 3 is a cross-sectional view taken along the line A-A in FIG. 2. FIG. 4 is an explanatory diagram illustrating a state in which one connecting body and one manifold of FIG. 2 are separated, and the other connecting body and the other manifold are connected. FIG. 5 is an explanatory diagram illustrating a front view of an inner pipe, with the lower half cross-sectional, before the piping structure of FIG. 1 is manufactured. FIG. 6 is an explanatory diagram illustrating a step of forming one flared portion on the inner pipe of FIG. 5. FIG. 7 is an explanatory diagram illustrating a step of inserting one manifold onto the inner pipe of FIG. 6. FIG. 8 is an explanatory diagram illustrating a step of inserting an outer pipe onto the inner pipe of FIG. 7. FIG. 9 is an explanatory diagram illustrating a step of inserting the other manifold onto the inner pipe of FIG. 8. Fig. 10 is an explanatory view illustrating a state in which a reamer is being inserted into the other longitudinal portion of the inner pipe with the other manifold abutting against the other longitudinal end of the outer pipe of Fig. 9. Fig. 11 is an explanatory view illustrating a step of forming the other flared portion on the inner pipe of Fig. 10. Fig. 12 is an explanatory view illustrating a step of screwing connectors into the respective manifolds of Fig. 11. Fig. 13 is an explanatory view illustrating a longitudinal cross section of a portion of another embodiment of the piping structure.

[0011] Hereinafter, a piping structure of a heat exchanger and a manufacturing method thereof according to the present invention will be described based on an embodiment shown in the drawings.

[0012] The embodiment of the piping structure of the heat exchanger 1 illustrated in Figures 1 to 4 includes an inner pipe 2 and an outer pipe 3 constituting a double-pipe structure, two cylindrical manifolds 4A, 4B, and two pipes 5a, 5b. This piping structure also includes annular seals S1, S1 for the outer pipe interposed between each of the manifolds 4A, 4B and the outer pipe 3, two connecting inner pipes 6, 6, and two cylindrical connecting bodies 7A, 7B. One manifold 4A, the outer pipe 3, and the other manifold 4B are arranged in this order between one connecting body 7A and the other connecting body 7B. One connecting inner pipe 6 is fitted around one connecting inner pipe 6, and the other connecting inner pipe 6 is fitted around the other connecting inner pipe 6. One connecting inner pipe 6 is connected to one longitudinal end of the inner pipe 2, and the other connecting inner pipe 6 is connected to the other longitudinal end of the inner pipe 2. The dashed line CL in the drawing indicates the cylindrical axis of the inner tube 2, the outer tube 3, the manifolds 4A and 4B, and the connecting bodies 7A and 7B.

[0013] The inner pipe 2, manifolds 4A, 4B, pipe bodies 5a, 5b, connecting inner pipes 6, 6, and coupling bodies 7A, 7B are each made of metal or a known material, while the outer pipe 3 is made of metal or a polymeric material such as resin or a known material. Although the outer pipe 3 may be made of stainless steel, the inner pipe 2, outer pipe 3, manifolds 4A, 4B, pipe bodies 5a, 5b, connecting inner pipes 6, 6, and coupling bodies 7A, 7B are preferably made of the same material, for example, aluminum or an aluminum alloy.

[0014] The sizes of the inner pipe 2, outer pipe 3, and pipe bodies 5a, 5b vary depending on the performance required of the heat exchanger 1, but the outer diameter of the inner pipe 2 is, for example, about 4 mm to 500 mm, the outer diameter of the outer pipe 3 is, for example, about 8 mm to 500 mm, and the outer diameter of the pipe bodies 5a, 5b is, for example, about 4 mm to 500 mm. The sizes of the manifolds 4A, 4B, the connecting inner pipes 6, 6, and the coupling bodies 7A, 7B are appropriately set based on the sizes of the inner pipe 2 and outer pipe 3, etc.

[0015] Cylindrical flared portions 2a, 2b that increase in diameter toward the longitudinal ends are formed at both longitudinal ends of the inner pipe 2. The flared portions 2a, 2b are formed by processing the inner pipe 2.

[0016] Each of the manifolds 4A, 4B is fitted onto the inner tube 2 and installed at both longitudinal ends of the outer tube 3. Each of the manifolds 4A, 4B has a through hole 4c, a through hole 4d, and a tapered through hole 4e between one end and the other end in the cylindrical axis direction, and an internal space P3 is formed between the through holes 4c and 4d in the cylindrical axis direction. In this embodiment, each of the manifolds 4A, 4B has a cylindrical flange portion 4f with a reduced diameter at one end in the cylindrical axis direction, and the inner peripheral surface of this flange portion 4f forms the through hole 4c.

[0017] Furthermore, threaded portions 4g, 4g are formed on the outer peripheral surfaces of the longitudinal ends of each of the manifolds 4A, 4B, and tapered through holes 4e, 4e extending in the longitudinal direction are formed on the inner peripheral surfaces of the threaded portions 4g. That is, the outer peripheral sides of the tapered through holes 4e, 4e are threaded portions 4g, 4g.

[0018] One connecting inner pipe 6 is connected to one longitudinal end (flared portion 2a) of the inner pipe 2. The other connecting inner pipe 6 is connected to the other longitudinal end (flared portion 2b) of the inner pipe 2. The longitudinal ends of each connecting inner pipe 6, 6 facing the respective flared portions 2a, 2b are formed into tapered cylindrical portions 6a, 6a with reduced diameters. Each tapered cylindrical portion 6a, 6a is inserted into the opposing flared portion 2a, 2b.

[0019] Each of the connecting bodies 7A and 7B has a threaded portion 7c formed on the cylindrical inner peripheral surface. One connecting inner pipe 6 is inserted into the connecting body 7A, and the other connecting inner pipe 6 is inserted into the other connecting body 7B.

[0020] In this embodiment, each connecting inner pipe 6 has a bead portion 6b that protrudes outward from the outer circumferential surface near the tapered tubular portion 6a. Each bead portion 6b extends annularly in the circumferential direction on the outer circumferential surface of the connecting inner pipe 6. The bead portion 6b is formed by processing the connecting inner pipe 6. The bead portion 6b may be formed by a known method. For example, the bead portion 6b is formed by performing bead processing (stringing processing) on ​​the connecting inner pipe 6, causing a portion of the connecting inner pipe 6 to protrude outward.

[0021] The protruding height of the bead portion 6b toward the outer periphery may be any height that can restrict movement in one longitudinal direction of the coupling bodies 7A, 7B that are extrapolated onto the connecting inner pipe 6. The protruding height of the bead portion 6b varies depending on the outer diameter of the connecting inner pipe 6, but is, for example, 2 mm or more. The bead portion 6b is not limited to the specifications exemplified in this embodiment, and may be any height that can restrict movement of the coupling bodies 7A, 7B in one longitudinal direction of the connecting inner pipe 6.

[0022] When the threaded portion 4g (male threaded portion) of one manifold 4A is threadedly engaged with the threaded portion 7c (female threaded portion) of one connecting body 7A, the tapered tubular portion 6a inserted into the flared portion 2a of one manifold 4A and its flared portion 2a are pressed from the outer periphery by the inner circumferential surface of the tapered through hole 4e of one manifold 4A, so that the tapered tubular portion 6a, its flared portion 2a, and its inner circumferential surface of the tapered through hole 4e are integrated and closely fitted together. Similarly, when the threaded portion 4g (male threaded portion) of the other manifold 4B is threadedly engaged with the threaded portion 7c (female threaded portion) of the other connecting body 7B, the tapered tubular portion 6a inserted into the flared portion 2b of the other manifold 4B and its flared portion 2b are pressed from the outer periphery by the inner circumferential surface of the tapered through hole 4e of the other manifold 4B, so that the tapered tubular portion 6a, its flared portion 2b, and its inner circumferential surface of the tapered through hole 4e are integrated and closely fitted together.

[0023] The inner pipe 2 communicates with the tapered through-holes 4e, 4d, and 4c of one manifold 4A and the through-holes 4c, 4d, and 4e of the other manifold 4B. The flange portion 4f of one manifold 4A is inserted into one longitudinal end of the outer pipe 3, and the flange portion 4f of the other manifold 4B is inserted into the other longitudinal end of the outer pipe 3. Both longitudinal ends of the outer pipe 3 are sealed by the manifolds 4A and 4B. It is preferable to minimize the gap between the inner circumferential surface of the outer pipe 3 and the outer circumferential surface of each flange portion 4f, for example, 1 mm or less. It is also preferable to minimize the gap between the outer circumferential surface of the inner pipe 2 and the inner circumferential surface of each through-hole 4d, for example, 1 mm or less.

[0024] More specifically, seal materials S1, S1 are interposed between each of the manifolds 4A, 4B and the outer pipe 3. In this embodiment, seal materials S1, S1 are disposed between the outer peripheral surfaces of the flange portions 4f, 4f and the inner peripheral surface of the outer pipe 3, sealing the gaps therebetween.

[0025] The sealing material S1 may be any of various known sealing materials that seal gaps airtightly, such as an O-ring made of various known elastic materials such as silicone rubber, various gaskets, various packings, and various adhesives.

[0026] The outer peripheral surface of the tapered tubular portion 6a of one connecting inner pipe 6 and the inner peripheral surface of one flared portion 2a are in close contact with each other, thereby sealing the gap between them airtight (metal seal). The outer peripheral surface of one flared portion 2a is in close contact with the inner peripheral surface of the tapered through hole 4e of one manifold 4A, thereby sealing the gap between them airtight (metal seal). Similarly, the outer peripheral surface of the tapered tubular portion 6a of the other connecting inner pipe 6 is in close contact with the inner peripheral surface of the other flared portion 2b, thereby sealing the gap between them airtight (metal seal). The outer peripheral surface of the other flared portion 2b is in close contact with the inner peripheral surface of the tapered through hole 4e of the other manifold 4B, thereby sealing the gap between them airtight (metal seal).

[0027] One longitudinal end face of the outer pipe 3 abuts against an end face of one manifold 4A that is closer to the outer periphery than the flange portion 4f, and the other longitudinal end face of the outer pipe 3 abuts against an end face of the other manifold 4B that is closer to the outer periphery than the flange portion 4f.

[0028] In this piping structure, one manifold 4A is sandwiched between one connecting body 7A and one longitudinal end of the outer pipe 3, and is installed so that its longitudinal movement is restricted. The other manifold 4B is sandwiched between the other connecting body 7B and the other longitudinal end of the outer pipe 3, and is installed so that its longitudinal movement is restricted. Therefore, one manifold 4A, the outer pipe 3, and the other manifold 4B are installed between the connecting body 7A and the connecting body 7B, and are substantially fixed in place with respect to the longitudinal direction of the inner pipe 2.

[0029] One pipe 5a is brazed to the outer circumferential surface of one manifold 4A, and the other pipe 5b is brazed to the outer circumferential surface of the other manifold 4b. These manifolds 4A, 4B and the pipes 5a, 5b are brazed together using a known brazing material that is suitable for the materials of these manifolds.

[0030] The flow path P2 of one tube 5a is in communication with the internal space P3 of one manifold 4A brazed to this tube 5a. The flow path P2 of the other tube 5b is in communication with the internal space P3 of the other manifold 4B brazed to this tube 5b. The flow path P1 between the outer peripheral surface of the inner tube 2 and the inner peripheral surface of the outer tube 3 is in communication with the outer peripheral region of the inner tube 2 in the internal spaces P3, P3 of each manifold 4A, 4B. Therefore, the flow path P2 of one tube 5a is in communication with the outer peripheral region of the inner tube 2 in the internal space P3 of one manifold 4A, the flow path P1 between the outer peripheral surface of the inner tube 2 and the inner peripheral surface of the outer tube 3, the outer peripheral region of the inner tube 2 in the internal space P3 of the other manifold 4B, and the flow path P2 of the other tube 5b. The flow paths of each connecting inner tube 6 are in communication with the flow paths of the inner tube 2.

[0031] As shown in FIG. 2 , the high-temperature fluid HF flows from the flow path P2 of one pipe body 5a through the outer peripheral region of the inner pipe 2 in the internal space P3 of one manifold 4A, the flow path P1 between the outer peripheral surface of the inner pipe 2 and the inner peripheral surface of the outer pipe 3, the outer peripheral region of the inner pipe 2 in the internal space P3 of the other manifold 4B, and then into the flow path P2 of the other pipe body 5b. The low-temperature fluid LF flows from the flow path of one connecting inner pipe 6 through the flow path of the inner pipe 2 and the flow path of the other connecting inner pipe 6. Between the inner pipe 2 and the outer pipe 3 of the double-pipe structure, the thermal energy of the high-temperature fluid HF is transferred to the low-temperature fluid LF, so that the temperature of the high-temperature fluid HF decreases and the temperature of the low-temperature fluid LF increases. In this way, heat exchange between the high-temperature fluid HF and the low-temperature fluid LF occurs in the heat exchanger 1. This heat exchanger 1 is applicable to, for example, air conditioners installed in vehicles such as automobiles, and air conditioners installed in homes, factories, and various facilities.

[0032] An example of a procedure for manufacturing the piping structure of the heat exchanger 1 will now be described.

[0033] As shown in Fig. 5, an inner pipe 2 of a predetermined length is prepared. Next, as shown in Fig. 6, a reamer 8 is inserted into one longitudinal end of the inner pipe 2 to form one flared portion 2a, which expands in diameter toward the outer periphery, at one longitudinal end of the inner pipe 2. The flared portion 2a may be formed by any of various known methods.

[0034] Next, as shown in Fig. 7, one manifold 4A is fitted onto the inner pipe 2. A seal material S1 is attached to this manifold 4A in advance. One pipe body 5a is brazed to the outer circumferential surface of the manifold 4A. As shown in Fig. 8, the outer circumferential surface of one flared portion 2a is brought into contact with the inner circumferential surface of the tapered through-hole 4e of the fitted manifold 4A.

[0035] Next, as shown in Fig. 8, the outer pipe 3 is fitted onto the inner pipe 2, and the longitudinal end face of the outer pipe 3 facing the manifold 4A is abutted against the end face of the manifold 4A as shown in Fig. 9. Next, as shown in Fig. 9, the other manifold 4A is fitted onto the inner pipe 2. A seal material S1 is attached to this manifold 4B in advance. In addition, the other pipe body 5b is brazed to the outer peripheral surface of the manifold 4B.

[0036] As illustrated in Figure 10, the longitudinal end face of the outer tube 3 facing the manifold 4B is abutted against the end face of the manifold 4B, and at the position where the outer tube 3 is sandwiched between the respective manifolds 4A, 4B, the gap between the respective manifolds 4A, 4B and the outer tube 3 is sealed with the respective sealing materials S1, S1, and both longitudinal ends of the outer tube 3 are sealed by the respective manifolds 4A, 4B.

[0037] Next, as illustrated in Fig. 10, a reamer 8 is inserted into the other longitudinal end of the inner pipe 2 to form the other flared portion 2b at the other longitudinal end of the inner pipe 2. As a result, as illustrated in Fig. 11, the outer peripheral surface of the other flared portion 2b comes into contact with the inner peripheral surface of the tapered through-hole 4e of the other manifold 4B.

[0038] 12 , the threaded portion 4g of one manifold 4A is threadedly engaged with the threaded portion 7c of one coupling body 7A that is fitted onto one connecting inner tube 6. As a result, the tapered tubular portion 6a of one connecting inner tube 6 inserted into one flared portion 2a and its flared portion 2a are pressed from the outer periphery by the inner periphery of the tapered through hole 4e of one manifold 4A, and the tapered tubular portion 6a, its flared portion 2a, and the inner periphery of the tapered through hole 4e are integrated and tightly fitted together. As a result, the outer periphery of the tapered tubular portion 6a and the inner periphery of one flared portion 2a are tightly fitted together, sealing the gap between them airtight (metal seal), and the outer periphery of one flared portion 2a and the inner periphery of the tapered through hole 4e of one manifold 4A are tightly fitted together, sealing the gap between them airtight (metal seal). Then, one manifold 4A is sandwiched between one connecting body 7A and one longitudinal end of the outer pipe 3, and is installed while restricting movement in the longitudinal direction.

[0039] Similarly, the threaded portion 4g of the other manifold 4B is screwed onto the threaded portion 7c of the other connecting body 7B, and the tapered cylindrical portion 6a and its flared portion 2b of the other connecting inner tube 6 inserted into the other flared portion 2b are pressed from the outer periphery by the inner circumferential circle of the tapered through hole 4e of the other manifold 4B, so that the tapered cylindrical portion 6a, its flared portion 2b, and the inner circumferential surface of the tapered through hole 4e are integrated and tightly fitted together. As a result, the outer circumferential surface of the tapered cylindrical portion 6a of the other connecting inner tube 6 and the inner circumferential surface of the other flared portion 2b are tightly fitted together, hermetically sealing the gap between them (metal seal), and the outer circumferential surface of the other flared portion 2b and the inner circumferential surface of the tapered through hole 4e of the other manifold 4B are tightly fitted together, hermetically sealing the gap between them (metal seal). The other manifold 4B is then sandwiched between the other connecting body 7B and the other longitudinal end of the outer pipe 3, and is installed while restricting movement in the longitudinal direction.

[0040] In this way, the piping structure illustrated in FIG. 2 is manufactured, in which one manifold 4A, the outer pipe 3, and the other manifold 4B are arranged in this order between one connecting body 7A and the other connecting body 7B.

[0041] According to the piping structure of the heat exchanger 1 described above, the manifolds 4A, 4B can be installed together with the outer pipe 3 while restricting longitudinal movement using the connecting bodies 7A, 7B arranged at two locations spaced apart along the longitudinal direction of the inner pipe 2. Additionally, the manifolds 4A, 4B are sealed between the outer pipe 3 and the manifolds 4A, 4B by the respective sealing materials S1, S1. The tapered tubular portions 6a, 6a of the connecting inner pipes 6, 6, the corresponding flared portions 2a, 2b of the inner pipe 2, and the inner circumferential surfaces of the tapered through holes 4e of the corresponding manifolds 4A, 4B are integrated and tightly fitted together, thereby sealing the manifolds 4A, 4B from the inner pipe 2. Brazing is required only for connecting the manifolds 4A, 4B to the corresponding pipe bodies 5a, 5b. The brazing process for connecting the manifolds 4A, 4B and the corresponding pipe bodies 5a, 5b while ensuring airtightness requires a considerable amount of time and high skill. Therefore, this embodiment, which requires only two brazing locations, contributes greatly to eliminating the complexity of the manufacturing process of this piping structure. Accordingly, in this manufacturing process, the inner pipe 2 and the outer pipe 3 are not heated by the brazing operation, which is advantageous in suppressing thermal deterioration of the inner pipe 2 and the outer pipe 3.

[0042] One manifold 4A and one connecting body 7A, and the other manifold 4B and the other connecting body 7B are connected by threading their respective threaded portions 4g, 7c together and can be separated by unscrewing them. This allows the double-pipe portion formed by the inner pipe 2 and outer pipe 3 to be easily separated from the respective connecting bodies 7A, 7B and the respective connecting inner pipes 6, 6, and also allows this double-pipe portion to be easily separated from the respective manifolds 4A, 4B. While it has been difficult to replace parts of a piping structure in the past, this embodiment makes it possible to replace parts of the piping structure as needed. For example, damaged or deformed parts can be quickly replaced, improving the maintainability of the piping structure.

[0043] In this embodiment, one manifold 4A is brazed to one of the tubes 5a before being fitted onto the inner tube 2. Also, the other manifold 4B is brazed to the other tube 5b before being fitted onto the inner tube 2. As in this embodiment, brazing the manifolds 4A, 4B to the corresponding tubes 5a, 5b before assembling the inner tube 2, outer tube 3, and manifolds 4A, 4B further simplifies the assembly process.

[0044] It is also possible to install one manifold 4A by clamping it between one connecting body 7A and one longitudinal end of the outer pipe 3 to restrict its longitudinal movement, and install the other manifold 4B by clamping it between the other connecting body 7B and the other longitudinal end of the outer pipe 3 to restrict its longitudinal movement, and then braze each manifold 4A, 4B to the corresponding pipe bodies 5a, 5b. By using this procedure, it is possible to prevent the pipe bodies 5a, 5b from getting in the way during the process of assembling the inner pipe 2, outer pipe 3, and manifolds 4A, 4B.

[0045] 13 is different from the previous embodiment in that only an annular seal S2 for the inner pipe is added. That is, the seal S2 is interposed between the inner pipe 2 and each of the connecting inner pipes 6, 6. As with the seal S1, various seal materials can be used for this seal S2.

[0046] In this embodiment, a seal material S2 is disposed on the outer peripheral surface of the connecting inner pipe 6 near the bead portion 6b. Therefore, the gaps between the inner peripheral surfaces of the respective flared portions 2a, 2b and the outer peripheral surfaces of the respective tapered tubular portions 6a facing them are complementarily sealed by the respective seal materials S2. According to this embodiment, the inner pipe 2 and the respective connecting inner pipes 6 are more reliably airtightly connected. Furthermore, the flow paths of the respective connecting inner pipes 6 and the inner pipe 2, which are in communication with each other, are isolated from the flow path between the outer peripheral surface of the inner pipe 2 and the inner peripheral surface of the outer pipe 3 by the respective seal materials S2. Therefore, it is even more advantageous to reliably prevent the low-temperature fluid LF and the high-temperature fluid HF from mixing.

[0047] REFERENCE SIGNS LIST 1 Heat exchanger 2 Inner pipe 2a, 2b Flare portion 3 Outer pipe 4A, 4B Manifold 4c, 4d Through hole 4e Tapered through hole 4f Flange portion 4g Threaded portion 5a, 5b Pipe body 6 Connecting inner pipe 6a Tapered cylindrical portion 6b Bead portion 7A, 7B Connecting body 7c Threaded portion 8 Reamer S1 Annular seal material for outer pipe S2 Annular seal material for inner pipe P1, P2 Flow path P3 Internal space LF Low temperature fluid HF High temperature fluid

Claims

1. A piping structure for a heat exchanger comprising inner and outer pipes forming a double pipe structure, a cylindrical manifold inserted onto the inner pipe and installed at both longitudinal ends of the outer pipe, and pipe bodies brazed to each of the manifolds, wherein the longitudinal ends of the outer pipe are sealed by each of the manifolds, a flow path of each of the pipe bodies is in communication with an internal space of the manifold to which the manifold is brazed, and a flow path between the outer circumferential surface of the inner pipe and the inner circumferential surface of the outer pipe is in communication with an outer circumferential region of the inner pipe in the internal space of each of the manifolds, the piping structure comprising: an annular seal material for the outer pipe interposed between each of the manifolds and the outer pipe, one connecting inner pipe connected to one longitudinal end of the inner pipe, the other connecting inner pipe connected to the other longitudinal end of the inner pipe, one cylindrical connector inserted onto the one connecting inner pipe, and the other cylindrical connector inserted onto the other connecting inner pipe, a flared portion is formed at both longitudinal ends of the inner tube, and longitudinal ends of each of the connecting inner tubes opposing each of the flared portions are formed into tapered tubular portions to be inserted into the flared portions, a threaded portion is formed on an outer peripheral surface of a longitudinal end of each of the manifolds, and a tapered through hole extending in the longitudinal direction is formed on an inner peripheral surface, the threaded portion of one of the manifolds and the threaded portion of one of the connecting bodies are screwed together, so that the tapered tubular portion inserted into one of the flared portions and its flared portion are pressed from the outer periphery by the inner peripheral surface of the tapered through hole of one of the manifolds, so that the tapered tubular portion, its flared portion and the inner peripheral surface of the tapered through hole are integrated and tightly attached, and one of the manifolds is sandwiched between the one of the connecting bodies and one longitudinal end of the outer tube, and is installed such that movement in the longitudinal direction is restricted,As a result of the threaded portion of the other manifold and the threaded portion of the other connecting body being screwed together, the tapered cylindrical portion inserted into the flare portion of the other manifold and its flare portion are pressed from the outer circumferential side by the inner circumferential surface of the tapered through hole of the other manifold, so that the tapered cylindrical portion, its flare portion and the inner circumferential surface of the tapered through hole are integrated and tightly attached, and the other manifold is clamped between the other connecting body and the other longitudinal end of the outer tube, thereby restricting its longitudinal movement. This is a piping structure of a heat exchanger.

2. A piping structure for a heat exchanger as described in claim 1, wherein each of the manifolds has a cylindrical flange portion that is inserted into the outer pipe, and an annular sealing material for the outer pipe is disposed between the outer peripheral surface of each of the flange portions and the inner peripheral surface of the outer pipe.

3. A piping structure for a heat exchanger according to claim 1 or 2, further comprising an annular seal for the inner pipe interposed between said inner pipe and each of said connecting inner pipes.

4. A method for manufacturing a piping structure of a heat exchanger having a double pipe structure consisting of an inner pipe and an outer pipe, a cylindrical manifold inserted onto the inner pipe and installed at both longitudinal ends of the outer pipe, and tube bodies brazed to each of the manifolds, comprising the steps of: preparing one connecting inner pipe connected to one longitudinal end of the inner pipe, the other connecting inner pipe connected to the other longitudinal end of the inner pipe, one cylindrical coupling body inserted onto the one connecting inner pipe, and the other cylindrical coupling body inserted onto the other connecting inner pipe; forming a threaded portion on the outer peripheral surface of the longitudinal end of each of the manifolds and forming a tapered through hole extending longitudinally on the inner peripheral surface; forming one longitudinal end of each of the connecting inner pipes into a tapered cylindrical portion; one flare portion is formed at one longitudinal end of the inner tube, one of the manifolds is inserted onto the inner tube so that the one flare portion comes into contact with the inner peripheral surface of the tapered through hole of one of the manifolds, the outer tube is inserted onto the inner tube, and then the other manifold is inserted onto the inner tube, and the space between each of the manifolds and the outer tube is sealed with annular sealing materials for the outer tube at a position where the outer tube is sandwiched between the respective manifolds, and both longitudinal ends of the outer tube are sealed with the respective manifolds; the other flare portion is formed at the other longitudinal end of the inner tube so that the other flare portion comes into contact with the inner peripheral surface of the tapered through hole of the other manifold, the threaded portion of one of the manifolds is screwed into the threaded portion of the one of the connecting bodies, and the tapered tubular portion and its flared portion of the one of the connecting inner tubes inserted into the one of the flared portions are pressed from the outer circumferential side by the inner circumferential surface of the tapered through hole of the one of the manifolds, so that the tapered tubular portion, the flared portion and the inner circumferential surface of the tapered through hole are integrated and tightly attached to each other, and the one of the manifolds is clamped between the one of the connecting bodies and one longitudinal end of the outer tube to restrict longitudinal movement thereof, and installed;the threaded portion of the other manifold is screwed into the threaded portion of the other connecting body, and the tapered cylindrical portion of the other connecting inner tube inserted into the flared portion of the other connecting inner tube and its flared portion are pressed from the outer circumferential side by the inner circumferential circle of the tapered through hole of the other manifold, so that the tapered cylindrical portion, the flared portion and the inner circumferential surface of the tapered through hole are integrated and tightly attached to each other, and the other manifold is clamped between the other connecting body and the other longitudinal end of the outer tube to restrict longitudinal movement and install it; A manufacturing method for a piping structure of a heat exchanger, which connects a flow path between the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube with an outer peripheral region of the inner tube in the internal space of one of the manifolds and the other of the manifolds, connects a flow path of one of the tube bodies brazed to one of the manifolds with the internal space of one of the manifolds, and connects a flow path of the other of the tube bodies brazed to the other manifold with the internal space of the other manifold.

5. A method for manufacturing a piping structure of a heat exchanger as described in claim 4, wherein one of the manifolds is brazed to one of the pipe bodies before inserting one of the manifolds onto the inner pipe, and the other of the manifolds is brazed to the other of the pipe bodies before inserting the other of the manifolds onto the inner pipe.

6. A method for manufacturing a piping structure of a heat exchanger as described in claim 4, comprising the steps of: installing one of the manifolds by clamping it between one of the connecting bodies and one longitudinal end of the outer pipe to restrict its longitudinal movement; and installing the other of the manifolds by clamping it between the other of the connecting bodies and the other longitudinal end of the outer pipe to restrict its longitudinal movement; and then brazing one of the manifolds to one of the pipe bodies and brazing the other of the manifolds to the other of the pipe bodies.

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