Method for producing plate-type heat exchanger, and plate-type heat exchanger

Abstract

A method for producing a plate-type heat exchanger includes: a step in which a second brazing material is disposed on a portion of the outer surface of an outermost-side heat transfer plate, the portion surrounding a through-hole; a step in which a base end of a pipe member is inserted into the through-hole from the outer surface of the outermost-side heat transfer plate and a larger-diameter portion thereof is made to adjoin the outer surface of the outermost-side heat transfer plate, thereby attaching the pipe member to the outermost-side heat transfer plate; and a step in which the outermost-side heat transfer plate to which the pipe member has been attached is heated to melt the second brazing material and a clad layer, thereby brazing the base end of the pipe member onto the inner wall of the through-hole of the outermost-side heat transfer plate.

Description

Title of Invention METHOD FOR PRODUCING PLATE-TYPE HEAT EXCHANGER, AND PLATE TYPE HEAT EXCHANGER Technical Field [0001 ] The present disclosure relates to a method for manufacturing a plate heat exchanger and a plate heat exchanger. Background Art

[0002] Some heat exchangers include a pipe connected to the heat exchanger to allow a fluid to flow into and out of a flow space in the heat exchanger from and to an external device.

[0003] For example, Patent Literature 1 describes a heat exchanger including an inflow pipe connected to a header tank. In this heat exchanger, the inflow pipe has, on an outer wall surface of an end portion, a ring-shaped protrusion spaced from a pipe end face and extending in a circumferential direction. The header tank has a through-hole to receive the end portion of the inflow pipe. The inner wall surface of the header tank is covered with a cladding layer formed from a brazing material. In the heat exchanger described in Patent Literature 1, the end portion of the inflow pipe is inserted into the through-hole in the header tank until the ring-shaped protrusion comes in contact with an outer wall surface of the header tank. The cladding layer on the inner wall surface of the header tank then melts to braze the end portion of the inflow pipe to the inner wall of the through-hole in the header tank. Citation List Patent Literature

[0004] Patent Literature 1: Unexamined Japanese Patent Application Publication No. 2005-156000 Summary of Invention Technical Problem

[0005] Heat exchangers include a plate heat exchanger including multiple heat transfer plates stacked on one another with flow spaces for a fluid defined between adjacent heat transfer plates. The plate heat exchanger may also include a pipe, such as a pipe fitting, connected to an outermost heat transfer plate of the multiple heat transfer plates for the fluid to flow into and out of the plate heat exchanger from and to an external device. In this case, the outermost heat transfer plate and the pipe fitting may be bonded with the method for bonding the header tank and the inflow pipe in the heat exchanger described in Patent Literature 1.

[0006] However, to bond the pipe fitting and the outermost heat transfer plate with the method for bonding the header tank and the inflow pipe in the heat exchanger described in Patent Literature 1, the cladding layer located on the inner surface of the outermost heat transfer plate melts to braze the pipe fitting to the outermost heat transfer plate. In this case, the brazing material may not sufficiently spread from the inner surface to the outer surface of the outermost heat transfer plate. The pipe fitting and the outermost heat transfer plate may thus not be bonded with sufficiently high strength.

[0007] In response to the above issue, an objective of the present disclosure is to provide a method for manufacturing a plate heat exchanger and a plate heat exchanger including a pipe bonded to an outermost heat transfer plate with higher strength. Solution to Problem

[0008] To achieve the above objective, a method according to an aspect of the present disclosure is a method for manufacturing a plate heat exchanger including a plurality of heat transfer plates and a pipe. In the plate heat exchanger, the plurality of heat transfer plates are stacked on one another with a flow space for a fluid defined between adj acent heat transfer plates of the plurality of heat transfer plates. At least an outermost heat transfer plate of the plurality of heat transfer plates has a through-hole through which the fluid flows into and out of the flow space. The outermost heat transfer plate includes a first brazing member located on an inner surface of the outermost heat transfer plate and surrounding the through-hole. The pipe includes a basal end portion and a larger-diameter portion having a larger outer diameter than the basal end portion. The basal end portion is brazed to an inner wall of the through-hole with the basal end portion extending through the through-hole and the larger-diameter portion adjoining an outer surface of the outermost heat transfer plate. The pipe is a pipe through which the fluid flows into and out of the flow space. The method includes placing a second brazing member on the outer surface of the outermost heat transfer plate to surround the through-hole, attaching the pipe to the outermost heat transfer plate by inserting the basal end portion of the pipe into the through-hole through the outer surface of the outermost heat transfer plate and adjoining the larger-diameter portion to the outer surface of the outermost heat transfer plate, and brazing the basal end portion of the pipe to the inner wall of the through-hole in the outermost heat transfer plate by heating the outermost heat transfer plate to which the pipe is attached and melting the first brazing member and the second brazing member. Advantageous Effects of Invention

[0009] The method for manufacturing a plate heat exchanger according to the above aspect of the present disclosure includes melting the brazing member placed to surround the through-hole on the outermost heat transfer plate, melting the first brazing member surrounding the through-hole on the inner surface of the outermost heat transfer plate, and brazing the basal end portion of the pipe to the inner wall of the through-hole in the outermost heat transfer plate. Thus, the brazing member fully spreads over both the outer and inner surfaces of the outermost heat transfer plate during brazing. The pipe can thus be bonded to the outermost heat transfer plate with higher strength. Brief Description of Drawings

[0010] FIG. 1 is a perspective view of a plate heat exchanger according to Embodiment 1 of the present disclosure; FIG. 2 is an exploded perspective view of the plate heat exchanger according to Embodiment 1 of the present disclosure; FIG. 3 is a perspective view of a pipe fitting included in the plate heat exchanger according to Embodiment 1 of the present disclosure; FIG. 4 is a perspective view of a reinforcing plate and the pipe fitting included in the plate heat exchanger according to Embodiment 1 of the present disclosure; FIG. 5 is a flowchart of a method for manufacturing the plate heat exchanger according to Embodiment 1 of the present disclosure; FIG. 6 is a cross-sectional view of the pipe fitting to which a metal foil film is attached in a metal foil attachment process in the method for manufacturing the plate heat exchanger according to Embodiment 1 of the present disclosure; FIG. 7 is a cross-sectional view of the reinforcing plate to which the pipe fitting is being attached in a pipe fitting attachment process in the method for manufacturing the plate heat exchanger according to Embodiment 1 of the present disclosure; FIG. 8 is a partially enlarged cross-sectional view of the reinforcing plate with the pipe fitting attached in the pipe fitting attachment process in the method for manufacturing the plate heat exchanger according to Embodiment 1 of the present disclosure; FIG. 9 is an enlarged cross-sectional view of area IX of the pipe fitting illustrated in FIG. 8 to be brazed in a brazing process in the method for manufacturing the plate heat exchanger according to Embodiment 1 of the present disclosure; FIG. 10 is a cross-sectional view of a pipe fitting in a modification used in the metal foil attachment process in the method for manufacturing the plate heat exchanger according to Embodiment 1 of the present disclosure; FIG. 11 is a partially enlarged cross-sectional view of the reinforcing plate and the metal foil film in a modification brazed in the brazing process in the method for manufacturing the plate heat exchanger according to Embodiment 1 of the present disclosure; FIG. 12 is a perspective view of a reinforcing plate and a pipe fitting included in a plate heat exchanger according to Embodiment 2 of the present disclosure; FIG. 13 is a partially enlarged cross-sectional view of the reinforcing plate with the pipe fitting attached in a pipe fitting attachment process in a method for manufacturing a plate heat exchanger according to Embodiment 2 of the present disclosure; FIG. 14 is a cross-sectional view of a rod-like brazing member and a pipe fitting used in a modification of the method for manufacturing the plate heat exchanger according to Embodiment 1 of the present disclosure; FIG. 15 is a cross-sectional view of a brazing member as a paste and a pipe fitting used in another modification of the method for manufacturing the plate heat exchanger according to Embodiment 1 of the present disclosure; and FIG. 16 is a cross-sectional view of a pipe fitting included in a plate heat exchanger according to still another modification of Embodiment 1 of the present disclosure. Description of Embodiments

[0011] A method for manufacturing a plate heat exchanger and a plate heat exchanger according to one or more embodiments of the present disclosure are described in detail below with reference to the drawings. Like reference signs denote like or corresponding components in the drawings. The orthogonal XYZ coordinate system in the drawings includes the Z-axis in the vertical direction, the Y-axis in the front-rear direction, and the X-axis in a direction orthogonal to the Z-axis and the Y-axis when the longitudinal direction of a rectangular heat transfer plate included in the plate heat exchanger is referred to as the vertical direction and the lateral direction of the heat transfer plate is referred as the front-rear direction. This coordinate system is referred to hereafter as appropriate.

[0012] Embodiment 1 A method for manufacturing a plate heat exchanger according to Embodiment 1 includes placing foil formed from a brazing material on a surface of a reinforcing plate as an outermost heat transfer plate through which a pipe fitting is inserted, and placing a cladding formed from a brazing material on a surface of the reinforcing plate opposite to the surface through which the pipe fitting is inserted to increase brazing strength by supplying a sufficient amount of brazing material in a brazing process performed after the pipe fitting is inserted into a through-hole in the reinforcing plate for assembly. The structure of the manufactured plate heat exchanger is described first with reference to FIGS. 1 to 4.

[0013] FIG. 1 is a perspective view of a plate heat exchanger 1A according to Embodiment 1. FIG. 2 is an exploded perspective view of the plate heat exchanger 1 A. FIG. 3 is a perspective view of each of pipe fittings 61 to 64 included in the plate heat exchanger 1 A. FIG. 4 is a perspective view of a reinforcing plate 30A and the pipe fitting 62 included in the plate heat exchanger 1 A. For ease of understanding, upright walls 11 of heat transfer plates 10 and upright walls 21 of heat transfer plates 20 are not illustrated in FIG. 1. Additionally, a cladding 31 in a reinforcing plate 30A and a cladding 41 in a reinforcing plate 40A are illustrated as different components in FIG. 2.

[0014] As illustrated in FIGS. 1 and 2, the plate heat exchanger 1A includes the multiple heat transfer plates 10 and the multiple heat transfer plates 20 stacked alternately on one another, and the reinforcing plates 30A and 40A reinforcing the stacked heat transfer plates 10 and 20.

[0015] The heat transfer plates 10 and 20 allow heat exchange between two different fluids, or a first fluid and a second fluid. More specifically, the heat transfer plates 10 are formed from a metal with high thermal conductivity, such as stainless steel. As illustrated in FIG. 2, the heat transfer plates 10 are rectangular plates with rounded comers. Each heat transfer plate 10 has the outer periphery surrounded by the upright wall 11 to define a flow space for the first fluid. The flow space in each heat transfer plate 10 includes inner fins 12 to facilitate heat transfer from the first fluid. A metal foil film 13 formed from pure copper or a copper alloy is located adjacent to the right surface of each heat transfer plate 10. The metal foil film 13 covering the right surface of the heat transfer plate 10 functions as a brazing member during manufacture to bond the heat transfer plate 10 to the corresponding heat transfer plate 20 when the heat transfer plate 10 is stacked together with the heat transfer plate 20. A brazing member herein refers to a component formed from a brazing material.

[0016] The heat transfer plates 20 are formed from the same material as the heat transfer plates 10 and have the same rectangular shape as the heat transfer plates 10. Each heat transfer plate 20 has the outer periphery surrounded by the upright wall 21 to define a flow space for the second fluid different from the first fluid. The flow space in each heat transfer plate 20 also includes inner fins 22 to increase heat conductivity. A metal foil film 23 formed from pure copper or a copper alloy is located adjacent to the right surface of each heat transfer plate 20. The metal foil film 23 covers the right surface of the heat transfer plate 20 to function as a brazing member during manufacture.

[0017] The heat transfer plates 10 and 20 are stacked alternately, with the plate surfaces having the above shape facing in the lateral direction, the upright walls 11 and 21 extending leftward, and the right surfaces being covered with the metal foil films 13 and 23. Each heat transfer plate 10 has flow openings 14 and 15 and communication openings 16 and 17 at the four corners. Each heat transfer plate 20 has communication openings 24 and 25 and flow openings 26 and 27 at the four comers to overlap the flow openings 14 and 15 and the communication openings 16 and 17 in the lateral direction. When the heat transfer plates 10 and 20 are stacked alternately, the flow openings 14 and 15, each defined with a peripheral wall protruding rightward, in each heat transfer plate 10 respectively connect with the communication openings 24 and 25 in the heat transfer plate 20 located on the right of the heat transfer plate 10. The flow openings 14 and 15 thus allow the first fluid to flow into and out of the heat transfer plate 10 located on the right of the heat transfer plate 20. The flow openings 26 and 27, each also defined with a peripheral wall protruding rightward, in each heat transfer plate 20 respectively connect with the communication openings 16 and 17 in the heat transfer plate 10 located on the right of the heat transfer plate 20. The flow openings 26 and 27 thus allow the second fluid to flow into and out of the heat transfer plate 20 located on the right of the heat transfer plate 10.

[0018] The heat transfer plates 10 and 20 having the above structures and stacked alternately in the lateral direction allow the first fluid and the second fluid to circulate and transfer heat from the first fluid and the second fluid to the heat transfer plates 10 and 20. Thus, when receiving inflow of the first fluid and the second fluid, the heat transfer plates 10 and 20 allow the first fluid and the second fluid to exchange heat. The heat transfer plates 10 and 20 stacked alternately are hereafter referred to as a stack 50. The stack 50 is held between the reinforcing plates 30A and 40A to reinforce the heat transfer plates 10 and 20.

[0019] The reinforcing plates 30A and 40A are rectangular plates with the same shape as the heat transfer plates 10 and 20. The reinforcing plate 30A is located on the left of the stack 50 with the plate surfaces facing in the lateral direction. The reinforcing plate 40A is located on the right of the stack 50 with the plate surfaces facing in the lateral direction. The reinforcing plates 30A and 40A arranged in this manner hold and reinforce the heat transfer plates 10 and 20.

[0020] As illustrated in FIG. 2, the reinforcing plate 30A has through-holes 32 and 33 to feed and discharge the first fluid to and from the stack 50. The through-hole 32 receives a pipe fitting 61, and the through-hole 33 receives a pipe fitting 62. The through-holes 32 and 33 have the rims of the openings chamfered as illustrated in FIG. 9 (described later) to facilitate bonding to the pipe fitting 61 and 62. The opening rims of the through-holes 32 and 33 thus have no burrs. The pipe fittings 61 and 62 are respectively brazed to the inner walls of the through-holes 32 and 33 to be bonded to the reinforcing plate 30A. Without burrs on the opening rims of the through-holes 32 and 33, a brazing material melted in the brazing process easily flows onto the inner walls of the through-holes 32 and 33.

[0021] The reinforcing plate 30A includes, on the right surface, a plate cladding 31 formed from a brazing material to be firmly bonded to the stack 50 during manufacture.

[0022] Similarly, the reinforcing plate 40A has through-holes 42 and 43 to feed and discharge the second fluid to and from the stack 50. The through-hole 42 receives a pipe fitting 63, and the through-hole 43 receives a pipe fitting 64. Although not illustrated, the through-holes 42 and 43 have the rims of the openings chamfered to allow a brazing material melted in the brazing process to easily flow onto the inner walls of the through-holes 42 and 43. The reinforcing plate 40A includes, on the left surface, a plate cladding 41 formed from the same brazing material as the cladding 31 to be firmly bonded to the stack 50.

[0023] FIG. 2 illustrates the reinforcing plate 30A and the cladding 31 as separate components for ease of understanding. However, the reinforcing plate 30A and the cladding 31 are assembled integrally and receive the pipe fittings 61 and 62 illustrated in FIG. 3. Similarly, although FIG. 2 illustrates the reinforcing plate 40A and the cladding 41 as separate components, the reinforcing plate 40A and the cladding 41 are assembled integrally and receive the pipe fittings 63 and 64 illustrated in FIG. 3. The pipe fittings 61 and 62 are bonded to the reinforcing plate 30A by melting the cladding 31 and spreading the brazing material of the cladding 31 into a gap between the inner wall of the through-hole 32 in the reinforcing plate 30A and the pipe fitting 61 and a gap between the inner wall of the through-hole 33 and the pipe fitting 62. The pipe fittings 63 and 64 are bonded to the reinforcing plate 40 A by melting the cladding 41 and spreading the brazing material of the cladding 41 into a gap between the inner wall of the through-hole 42 in the reinforcing plate 40A and the pipe fitting 63 and a gap between the inner wall of the through-hole 43 and the pipe fitting 64.

[0024] However, the brazing material spread by melting the cladding 31 alone may not sufficiently spread, through the gaps between the inner walls of the through-holes 32 and 33 in the reinforcing plate 30A and the respective pipe fittings 61 and 62, onto the left surface of the reinforcing plate 30A opposite to the surface with the cladding 31. This may lower the bonding strength of the pipe fittings 61 and 62. Similarly, the brazing material spread by melting the cladding 41 alone may not sufficiently spread, through the gaps between the inner walls of the through-holes 42 and 43 in the reinforcing plate 40A and the respective pipe fittings 63 and 64, onto the right surface of the reinforcing plate 40A opposite to the surface with the cladding 41. This may lower the bonding strength of the pipe fittings 63 and 64.

[0025] Thus, to increase the bonding strength by feeding a brazing material from the left surface of the reinforcing plate 30A opposite to the surface with the cladding 31, the plate heat exchanger 1A includes, on the left surface of the reinforcing plate 30A, a metal foil film 70 formed from a brazing material with a shape of a ring and surrounding the through-hole 33 in the reinforcing plate 30A that receives the pipe fitting 62 as illustrated in FIG. 4. The plate heat exchanger 1A further includes a bead 65 on the surface of the pipe fitting 62 to hold the metal foil film 70 between the bead 65 and the left surface of the reinforcing plate 30A.

[0026] Although not illustrated, the metal foil film 70 for increasing the bonding strength is also located on the left surface of the reinforcing plate 30A and surrounds the through-hole 32 in the reinforcing plate 30A that receives the pipe fitting 61. The bead 65 is also located on the surface of the pipe fitting 61 to hold the metal foil film 70.

[0027] Similarly, to increase the bonding strength by feeding a brazing material from the right surface of the reinforcing plate 40A opposite to the surface with the cladding 41, the metal foil film 70 is also located on the right surface of the reinforcing plate 40A and surround each of the through-holes 42 and 43 in the reinforcing plate 40A that receives the pipe fitting 63 or 64, although not illustrated. The bead 65 is also located on the surface of each of the pipe fittings 63 and 64 to hold the metal foil film 70 between the bead 65 and the right surface of the reinforcing plate 40A.

[0028] A method for manufacturing the plate heat exchanger 1A with the above structure is described in detail with reference to FIGS. 5 to 9.

[0029] FIG. 5 is a flowchart of a method for manufacturing the plate heat exchanger 1 A. In the method for manufacturing the plate heat exchanger 1A illustrated in FIG. 5, the heat transfer plates 10 and 20, the metal foil films 13 and 23, the reinforcing plates 30A and 40A, the claddings 31 and 41, and the pipe fittings 61, 62, 63, and 64 are preliminarily prepared with the shapes, dimensions, and quantities described above. The cladding 31 is preliminarily attached to the reinforcing plate 30A, and the cladding 41 to the reinforcing plate 40A.

[0030] As illustrated in FIG. 5, the method for manufacturing the plate heat exchanger 1A includes a metal foil attachment process (step SI). In the metal foil attachment process, the metal foil film 70 is attached to each of the pipe fittings 61, 62, 63, and 64. FIG. 6 illustrates an example in which the metal foil film 70 is attached to the pipe fitting 62 of the pipe fittings 61, 62, 63, and 64.

[0031] FIG. 6 is a cross-sectional view of the pipe fitting 62 to which the metal foil film 70 is attached in the metal foil attachment process in the method for manufacturing the plate heat exchanger 1 A.

[0032] As illustrated in FIG. 6, the pipe fitting 62 includes a basal end portion 66 to be attached to the through-hole 33 in the reinforcing plate 30A, the bead 65 located closer to a distal end of the pipe fitting 62 than the basal end portion 66, or located in the negative X-direction from the basal end portion 66, and a distal end portion 68 having a groove 67 to receive an O-ring.

[0033] The pipe fitting 62 is attached to the reinforcing plate 30A by swaging the basal end portion 66 inserted in the through-hole 33 in the reinforcing plate 30A (described later). To undergo this process, the basal end portion 66 has a cylindrical shape with an outer diameter DI insertable into the through-hole 33 in the reinforcing plate 30A. For the basal end portion 66 inserted in the through-hole 33 in the reinforcing plate 30A to undergo swaging, the basal end portion 66 has a length longer than the total thickness of the cladding 31, the reinforcing plate 30A, and the metal foil film 70, although not illustrated in FIG. 6.

[0034] The bead 65 protrudes outward from the basal end portion 66. More specifically, the bead 65 is formed by compressing and deforming a straight pipe in the axis direction of the pipe. The bead 65 thus has an annular flange shape with an outer diameter D2 larger than the outer diameter DI of the basal end portion 66. Thus, when the basal end portion 66 is placed through the ring of the metal foil film 70 (described later), the bead 65 comes in contact with the surface of the metal foil film 70 to position the metal foil film 70. The bead 65 includes flat side surfaces, or a flat positive-X surface in the positive X-direction and a flat negative-X surface in the negative X-direction to hold the metal foil film 70 between the bead 65 and the reinforcing plate 30A without a gap when the basal end portion 66 is inserted into the through-hole 33 in the reinforcing plate 30A. In other words, the bead 65 includes flat surfaces 653 and 654 orthogonal to the positive X-direction and the negative X-direction.

[0035] The distal end portion 68 has a cylindrical shape similarly to the basal end portion 66. The distal end portion 68 has an outer diameter D3 larger than the outer diameter DI of the basal end portion 66 and smaller than the outer diameter D2 of the bead 65. Thus, the outer diameter D2 of the bead 65 is the largest in the pipe fitting 62. This structure avoids the brazing material spreading from the basal end portion 66 beyond the bead 65 and reaching the distal end portion 68 in the brazing process (described later).

[0036] The pipe fitting 62 with this structure is formed from a metal, such as stainless steel, for strength.

[0037] The metal foil film 70 is formed from the same brazing material as the claddings 31 and 41, for example, pure copper or a copper alloy. The metal foil film 70 has a ring shape. More specifically, the metal foil film 70 has a flat annular shape with an inner diameter D4 larger than the outer diameter DI of the basal end portion 66 or the diameter of the through-hole 33 in the reinforcing plate 30A (described later), and an outer diameter D5 larger than the outer diameter D2 of the bead 65. The metal foil film 70 has a thickness T2 smaller than a thickness T1 of the bead 65. For example, the thickness T2 of the metal foil film 70 is about 0.15 to 0.20 mm when the thickness T1 of the bead 65 is 1.5 to 2.0 mm.

[0038] The outer diameter D5 of the metal foil film 70 may be sufficiently larger than the outer diameter D2 of the bead 65 by a visibly identifiable degree to prevent failure to attach the metal foil film 70 during manufacture. For example, the outer diameter D5 of the metal foil film 70 may be larger by 3 to 4 mm than the outer diameter D2 of the bead 65.

[0039] In the metal foil attachment process illustrated in FIG. 5, the metal foil film 70 with the above structure is attached to the pipe fitting 62 described above. More specifically, the basal end portion 66 of the pipe fitting 62 is placed through an annular hole in the metal foil film 70 to adjoin the flat surface 654 of the bead 65 on the pipe fitting 62 in FIG. 6 to the metal foil film 70. The metal foil film 70 is thus attached to the pipe fitting 62. Although not illustrated, the metal foil film 70 is also attached to each of the pipe fittings 61, 63, and 64 in the same manner as to the pipe fitting 62.

[0040] Referring back to FIG. 5, the metal foil attachment process is followed by a pipe fitting attachment process (step S2). FIGS. 7 and 8 illustrate an example structure in which the pipe fitting 62 of the pipe fittings 61, 62, 63, and 64 is attached to the reinforcing plate 30A.

[0041] FIG. 7 is a cross-sectional view of the reinforcing plate 30A to which the pipe fitting 62 is being attached in the pipe fitting attachment process in the method for manufacturing the plate heat exchanger 1 A. FIG. 8 is a partially enlarged cross sectional view of the reinforcing plate 30A with the pipe fitting 62 attached in the pipe fitting attachment process.

[0042] In the pipe fitting attachment process, the basal end portion 66 of the pipe fitting 62 is inserted, through the surface of the reinforcing plate 30A opposite to the surface with the cladding 31, or in other words, through the surface located in the negative X-direction, into the through-hole 33 in the reinforcing plate 30A to which the cladding 31 in FIG. 7 is attached. In this process, the basal end portion 66 of the pipe fitting 62 is inserted into the through-hole 33 in the reinforcing plate 30A until the metal foil film 70 attached to the pipe fitting 62 comes in contact with the negative-X surface of the reinforcing plate 30A and the metal foil film 70 is held between the reinforcing plate 30A and the flat surface 654 of the bead 65 on the pipe fitting 62. Thus, as illustrated in FIG. 7, the end face of the basal end portion 66 of the pipe fitting 62 is exposed through the positive-X surface of the cladding 31.

[0043] Subsequently, a truncated conical punch 80 is pushed into the internal space of the pipe fitting 62 that is open in the exposed end face of the basal end portion 66 to swage the basal end portion 66. The truncated conical punch 80 has, at the distal end, an outer diameter smaller than the inner diameter of the basal end portion 66, and, at the basal end, an outer diameter larger than the outer diameter of the basal end portion 66. Thus, as illustrated in FIG. 8, the inner diameter of the basal end portion 66 is larger at positions in the positive-X direction, and the end of the basal end portion 66 in the negative X-direction is larger than the diameter of the through-hole 33 in the reinforcing plate 30 A. In other words, the end of the basal end portion 66 in the negative X-direction has a larger diameter than the outer diameter DI illustrated in FIG. 6. The pipe fitting 62 is thus fixed to the reinforcing plate 30A. In addition, the reinforcing plate 30A is pushed by the punch 80 in the negative X-direction and thus comes in close contact with the metal foil film 70, allowing the metal foil film 70 to come in close contact with the bead 65. This adjusts a gap G between the reinforcing plate 30A and the bead 65 to have the same size as the thickness T2 of the metal foil film 70. The gap G thus has a uniform size that is appropriate for the brazing material to easily spread through capillary action in the brazing process (described later).

[0044] The through-hole 33 in the reinforcing plate 30A that receives the basal end portion 66 of the pipe fitting 62 connects with a through-hole 37 in the cladding 31 illustrated in FIG. 8. The through-hole 37 may be larger than the outer diameter of the swaged basal end portion 66. The cladding 31 having the above through-hole 37 reduces the likelihood that the cladding 31 defining the periphery of the through-hole extends to a space between the basal end portion 66 and the inner wall of the through-hole 33 in the reinforcing plate 30A to cause the pipe fitting 62 to incline with respect to the reinforcing plate 30A.

[0045] The pipe fitting 61 is fixed to the reinforcing plate 30A through the same process as the pipe fitting 62. Each of the pipe fittings 63 and 64 is also fixed to the reinforcing plate 40A through the same process as the pipe fitting 62.

[0046] As illustrated in FIG. 5, in a subsequent stacking process (step S3), the heat transfer plates 10 and 20 and the metal foil films 13 and 23 are stacked in the arrangement described above to form the stack 50. The stack 50 is held between the reinforcing plate 30A with the cladding 31 and the pipe fittings 61 and 62 and the reinforcing plate 40A with the cladding 41 and the pipe fittings 63 and 64.

[0047] In a pressing process after the stacking process (step S4), the stack 50 with the reinforcing plates 30A and 40A is pressed in the stacking direction for compression. Thus, the heat transfer plates 10 and 20, the metal foil films 13 and 23, and the reinforcing plates 30A and 40A included in the stack 50 are in close contact with one another.

[0048] After being compressed, the stack 50 undergoes the brazing process (step S5). More specifically, the stack 50 with the reinforcing plates 30A and 40A is placed in a furnace, and heated to a temperature at which the brazing material of the claddings 31 and 41 melts. Thus, the metal foil films 13 and 23 melt between the heat transfer plates 10 and 20, the metal foil film 70 attached to the pipe fitting 62 melts, and the claddings 31 and 41 in the stack 50 melt. The molten brazing material spreads into the gaps between the components. FIG. 9 illustrates the state of brazing of the pipe fitting 62 to the reinforcing plate 30A.

[0049] FIG. 9 is an enlarged cross-sectional view of area IX of the pipe fitting 62 illustrated in FIG. 8 to be brazed in the brazing process in the method for manufacturing the plate heat exchanger 1 A. The bead 65 on the pipe fitting 62 and the metal foil film 70 define a narrow gap that allows the molten brazing material to spread through capillary action. In FIG. 9, the narrow gap is illustrated in an enlarged manner for ease of understanding. FIG. 9 also illustrates a path for the brazing material to spread.

[0050] In the brazing process, the cladding 31 melts when heated to a temperature at which the brazing material melts. Thus, as indicated by arrow Al in FIG. 9, the molten brazing material spreads into the gap between the basal end portion 66 of the pipe fitting 62 and the cladding 31 and thus spreads into the gap between the basal end portion 66 and the inner wall of the through-hole 33 in the reinforcing plate 30 A.

[0051] The metal foil film 70 is located on the surface of the reinforcing plate 30A opposite to the surface with the cladding 31, or more specifically, on the negative-X surface of the reinforcing plate 30A. Thus, when the metal foil film 70 is heated to the temperature at which the brazing material melts, the metal foil film 70 melts, and the molten brazing material (hereafter simply referred to as the brazing material in the brazing process) is fed to the negative-X surface of the reinforcing plate 30A. The outer diameter D2 of the bead 65 is the largest on the pipe fitting 62, and the thickness T2 of the bead 65 is sufficiently greater than the thickness T1 of the metal foil film 70. Thus, the brazing material is less likely to spread beyond the bead 65 in the negative X-direction. The brazing material thus spreads in the positive X-direction, rather than in the negative X-direction with respect to the bead 65. Thus, as indicated by arrow A2 in FIG. 9, the brazing material spreads into the gap between the bead 65 on the pipe fitting 62 and the metal foil film 70 or the reinforcing plate 30A and into the gap between the basal end portion 66 of the pipe fitting 62 and the inner wall of the through-hole 33 in the reinforcing plate 30A. Thus, the brazing material spreads into the gap between the basal end portion 66 and the inner wall of the through-hole 33 from the negative-X surface in addition to from the positive-X surface of the reinforcing plate 30A.

[0052] When the brazing material flowing from the positive-X surface of the reinforcing plate 30A and the brazing material flowing from the negative-X surface meet in the gap between the basal end portion 66 and the inner wall of the through-hole 33, as indicated by arrow A3 in FIG. 9, the brazing material can move through the gap between the basal end portion 66 and the inner wall of the through-hole 33 toward the positive-X surface of the reinforcing plate 30A or the negative-X surface opposite to the positive-X surface. Thus, the brazing material fully fills, in addition to the gap between the basal end portion 66 and the inner wall of the through-hole 33, a gap between the cladding 31 and the basal end portion 66 adjacent to the positive-X surface of the reinforcing plate 30A and a gap between the metal foil film 70 and the bead 65 adjacent to the negative-X surface of the reinforcing plate 30A. This occurs independently of the size of gaps that may vary due to dimensional or assembly variations, and the brazing material flows through the gap between the basal end portion 66 and the inner wall of the through-hole 33 to fully fill these gaps. Thus, fillets 34 and 35 are formed in the gap between the basal end portion 66 and the cladding 31 and the gap between the bead 65 and the metal foil film 70.

[0053] After heated for a predetermined period in the brazing process, the stack 50 with the reinforcing plates 30A and 40A is cooled, solidifying the brazing material. The pipe fitting 62 is thus bonded to the reinforcing plate 30A. As described above, the brazing material fully spreads into, in addition to the gap between the basal end portion 66 and the inner wall of the through-hole 33 in the reinforcing plate 30 A, the gap between the basal end portion 66 and the cladding 31 and into the gap between the bead 65 and the metal foil film 70 to form the fillets 34 and 35. This firmly bonds the pipe fitting 62 and the reinforcing plate 30A. Although not illustrated, as in the brazing of the pipe fitting 62 to the reinforcing plate 30A, the brazing material also fully spreads into the gap between the pipe fitting 61 and the reinforcing plate 30A to braze the pipe fitting 61 to the reinforcing plate 30A. This firmly bonds the pipe fitting 61 and the reinforcing plate 30 A. As in the brazing of the pipe fitting 62 to the reinforcing plate 30 A, the brazing material also fully spreads into the gap between the pipe fittings 63 and 64 and the reinforcing plate 40A to braze the pipe fittings 63 and 64 to the reinforcing plate 40A. This firmly bonds the pipe fittings 63 and 64 and the reinforcing plate 40A. The pipe fittings 61 to 64 firmly bonded to the reinforcing plates 30A and 40A allow the plate heat exchanger 1A to be manufactured with high strength.

[0054] The reinforcing plates 30A and 40A described above transfer heat, and thus correspond to heat transfer plates in an aspect of the present disclosure. The reinforcing plates 30A and 40 A are examples of an outermost heat transfer plate in an aspect of the present disclosure. The claddings 31 and 41 are examples of a first brazing member or a cladding layer in an aspect of the present disclosure. The pipe fittings 61 to 64 are examples of a pipe in an aspect of the present disclosure. The bead 65 is an example of a larger-diameter portion in an aspect of the present disclosure. The metal foil film 70 is an example of a second brazing member in an aspect of the present disclosure.

[0055] The metal foil attachment process and the pipe fitting attachment process are processes of arranging the metal foil films 70 on the reinforcing plates 30A and 40A. As is clear from this, the metal foil attachment process and the pipe fitting attachment process are examples of a process of arranging the second brazing member in an aspect of the present disclosure. The pipe fitting attachment process is an example of a process of attaching a pipe to the outermost heat transfer plate in an aspect of the present disclosure.

[0056] As described above, the method for manufacturing the plate heat exchanger 1A according to Embodiment 1 includes a brazing process including melting the ringshaped metal foil films 70 located on the negative-X surface or the outer surface of the reinforcing plate 30A and surrounding the through-holes 32 and 33, melting the cladding 31 of a brazing material located on the positive-X surface or the inner surface of the reinforcing plate 30A, and brazing the basal end portions 66 of the pipe fittings 61 and 62 to the inner walls of the through-holes 32 and 33 in the reinforcing plate 30A. In the brazing process, the brazing material folly spreads over both the negative and positive-X surfaces of the reinforcing plate 30A, thus bonding the pipe fittings 61 and 62 to the reinforcing plate 30A with higher strength.

[0057] With the method for bonding the inflow pipe and the header tank in the heat exchanger described in Patent Literature 1, flux may be used to increase the fluidity of the brazing material in the brazing process. In contrast, the method for manufacturing the plate heat exchanger 1A includes melting the metal foil films 70 located on the outer surface of the reinforcing plate 30A and the cladding 31 located on the inner surface of the reinforcing plate 30A to feed the brazing material through both the surfaces of the reinforcing plate 30A, and thus can increase the fluidity of the brazing material without flux.

[0058] The method for manufacturing the plate heat exchanger 1A simply includes, for brazing, placing the metal foil films 70 on the outer surface of the reinforcing plate 30A, rather than placing the cladding 31 as on the inner surface. This method facilitates manufacture and reduces the material cost.

[0059] The method for manufacturing the plate heat exchanger 1A further includes a pipe fitting attachment process of swaging the basal end portion 66 of each of the pipe fittings 61 and 62 to hold the corresponding metal foil film 70 between the bead 65 on the pipe fitting 61 or 62 and the reinforcing plate 30A. Thus, the distance from the bead 65 to the reinforcing plate 30A is fixed. In other words, the gap between the bead 65 and the reinforcing plate 30A has a fixed size. The brazing material stably spreads into the gap between the bead 65 and the reinforcing plate 30A in the brazing process, thus avoiding lowering the bonding strength by insufficiently spreading into the gap.

[0060] The outer diameter D5 of the metal foil film 70 is larger than the outer diameter D2 of the bead 65 on each of the pipe fittings 61 and 62. Thus, when the metal foil film 70 is attached in the metal foil attachment process, the metal foil film 70 extends beyond the bead 65. This allows the operator to easily identify whether the metal foil film 70 is attached and thus prevents the operator from failing to attach the metal foil film 70.

[0061] The outer diameter D2 of the bead 65 on each of the pipe fittings 61 and 62 is the largest in the pipe fitting 61 or 62. The brazing material melting from the metal foil film 70 is thus less likely to spread beyond the bead 65 to the distal end portion 68 in the brazing process. In addition, the thickness T1 of the bead 65 is greater than the thickness T2 of the metal foil film 70. The brazing material is thus further less likely to spread to the distal end portion 68.

[0062] Modification As illustrated in FIG. 6, the pipe fitting 62 includes straight portions 655 and 656 located across the bead 65. The straight portions 655 and 656 may have lower wettability with the molten brazing material than the bead 65. With these straight portions 655 and 656, any brazing material extending beyond the bead 65 and flowing in the negative X-direction in the brazing process is less likely to spread further in the negative X-direction.

[0063] The bead 65 is formed by ironing using a die. The straight portions 655 and 656 thus have lower surface roughness than the bead 65. The straight portions 655 and 656 thus have lower wettability than the bead 65. The straight portions 655 and 656 may have lower wettability than the bead 65 formed by ironing.

[0064] The straight portion 655 may have lower wettability with the molten brazing material than the inner wall of the groove 67. The inner wall of the groove 67 has low surface roughness to improve the sealing performance of the O-ring. The straight portion 655 with lower wettability can thus reduce spreading of the brazing material into the groove 67.

[0065] The straight portion 655 is an example of a pipe portion adjacent to the larger-diameter portion and closer to the distal end than the basal end portion in an aspect of the present disclosure.

[0066] As illustrated in FIG. 6, in Embodiment 1, the distal end portion 68 of the pipe fitting 62 has the end face with a rounded outer periphery, but the distal end portion 68 of the pipe fitting 62 is not limited to this example.

[0067] FIG. 10 is a cross-sectional view of a pipe fitting 62 in a modification used in the metal foil attachment process.

[0068] As illustrated in FIG. 10, the distal end portion 68 of the pipe fitting 62 may have the end face with a right-angled outer periphery in a cross section, rather than the rounded outer periphery. The pipe fitting 62 can be formed into this shape by plastic processing. The pipe fitting 62 may be formed by plastic processing or by pipe expansion.

[0069] In Embodiment 1, as illustrated in FIG. 9, the metal foil film 70 has an inner circumferential surface inward from the inner wall of the through-hole 37 in the cladding 31, but the metal foil film 70 may be at a different position.

[0070] FIG. 11 is a partially enlarged cross-sectional view of the reinforcing plate 31 and the metal foil film 70 in a modification brazed in the brazing process.

[0071] As illustrated in FIG. 11, the inner circumferential surface of the metal foil film 70 and the inner wall surface of the through-hole 37 in the cladding 31 may be at the same position in the radial direction of the through-hole 37. This structure allows the brazing material to be fed uniformly from both the metal foil film 70 and the cladding 31 to the gap between the inner wall of the through-hole 33 in the reinforcing plate 31 and the basal end portion 66 of the pipe fitting 62 in the brazing process.

[0072] Embodiment 2 The plate heat exchanger 1A manufactured with the method for manufacturing the plate heat exchanger 1A according to Embodiment 1 includes the reinforcing plates 30A and 40A with flat surfaces facing outward, or flat outer surfaces. However, the reinforcing plates 30A and 40A are not limited to this example. The reinforcing plate 30A or 40A may have any structure including the through-hole 33 for a fluid to flow into and out of the flow space in the heat transfer plates 10 and 20, and the cladding 31 or 41 of a brazing material, or a cladding layer, on the inner surface. The outer surfaces of the reinforcing plates 30A and 40A may have any shape satisfying the above. For example, the outer surface of the reinforcing plate 30A or 40A may have a recess to receive an excess brazing material in the brazing process.

[0073] The method for manufacturing a plate heat exchanger IB according to Embodiment 2 uses a reinforcing plate 30B having a recess 36 located on the outer surface and surrounding the through-hole 3 3. With reference to FIGS. 12 and 13, the method for manufacturing the plate heat exchanger IB according to Embodiment 2 is described below. The components in Embodiment 2 are mainly described focusing on the differences from the components in Embodiment 1.

[0074] FIG. 12 is a perspective view of the reinforcing plate 30B and a pipe fitting 62 included in the plate heat exchanger IB according to Embodiment 2. FIG. 13 is a partially enlarged cross-sectional view of the reinforcing plate 30B with the pipe fitting 62 attached in the pipe fitting attachment process in the method for manufacturing the plate heat exchanger IB.

[0075] As illustrated in FIGS. 12 and 13, the manufactured plate heat exchanger IB has a groove-like recess 36 on the outer surface, or the negative-X surface, of the reinforcing plate 30B to circularly surround the through-hole 33.

[0076] The recess 36 is a groove recessed in the positive X-direction from the negative-X surface of the reinforcing plate 3 OB with a rectangular cross section as illustrated in FIG. 13. As illustrated in FIG. 12, the recess 36 extends annularly as described above. The annular recess 36 is concentric with the circular opening of the through-hole 33. The annular recess 36 has a diameter D6 larger than the inner diameter D4 of the metal foil film 70, and smaller than the outer diameter D5 of the metal foil film 70. Thus, as illustrated in FIG. 13, the recess 36 is covered with the metal foil film 70 when the metal foil film 70 is held between the bead 65 on the pipe fitting 62 and the reinforcing plate 30B in the pipe fitting attachment process in the method for manufacturing the plate heat exchanger IB. More specifically, the recess 36 is located in the positive X-direction from the metal foil film 70. This structure allows the brazing material to spread into the recess 36 when the metal foil film 70 melts in the brazing process in the method for manufacturing the plate heat exchanger IB. The recess 36 can thus store the excess brazing material resulting from the brazing process. The recess 36 thus reduces the likelihood that the brazing material spreads toward and beyond the bead 65 and reaches the distal end portion 68 of the pipe fitting 62 in the negative X-direction.

[0077] The recess 36 is located in the positive X-direction from the metal foil film 70. The recess 36 may be located in the positive X-direction from the protruding end of the bead 65 on the pipe fitting 62. The recess 36 may face the flat surface 654 that is the positive-X surface of the bead 65. The recess 36 at this position easily stores the excess brazing material in the brazing process.

[0078] The method for manufacturing the plate heat exchanger IB is the same as the method for manufacturing the plate heat exchanger 1A according to Embodiment 1 except for forming the recess 36 on the reinforcing plate 30B. Thus, the method is not described in detail.

[0079] As described above, in the plate heat exchanger IB manufactured with the method for manufacturing the plate heat exchanger IB according to Embodiment 2, the reinforcing plate 3 OB has the recess 36 located on the outer surface and surrounding the through-hole 33. Thus, the recess 36 stores the excess brazing material in the brazing process, and reduces the likelihood that the excess brazing material spreads over a portion other than the brazed portion. For example, the recess 36 reduces the likelihood that the excess brazing material reaches the distal end portion 68 of the pipe fitting 62. The O-ring is fitted to the distal end portion 68 of the pipe fitting 62, but no excess brazing material adheres to the distal end portion 68 of the pipe fitting 62. Thus, the method for manufacturing the plate heat exchanger IB allows the O-ring to be fitted more tightly. Thus, the pipe fitting 62 has increased airtightness and watertightness.

[0080] Although the methods for manufacturing the plate heat exchangers 1A and IB according to Embodiments 1 and 2 of the present disclosure and the plate heat exchangers 1A and IB have been described above, the method for manufacturing the plate heat exchangers 1A and IB, and the plate heat exchangers 1A and IB are not limited to these examples.

[0081] In Embodiments 1 and 2, for example, the inner diameter D4 of the metal foil film 70 is slightly larger than the outer diameter DI of the basal end portion 66 of the pipe fitting 62, and the outer diameter D5 of the metal foil film 70 is larger than the outer diameter D2 of the bead 65 on the pipe fitting 62. However, the inner diameter D4 and the outer diameter D5 of the metal foil film 70 are not limited to these examples. The metal foil film 70 may be any brazing member placeable on the outer surface of the reinforcing plate 30A, 30B, or 40A to surround the through-hole 32, 33, 42, or 43. Thus, the inner diameter D4 and the outer diameter D5 of the metal foil film 70 may each have any dimension satisfying this condition. The same applies to the thickness T2 of the metal foil film 70.

[0082] For example, the inner diameter D4 of the metal foil film 70 may be the same as the outer diameter DI of the basal end portion 66 of the pipe fitting 62. The outer diameter D5 of the metal foil film 70 may be the same as the outer diameter D2 of the bead 65 on the pipe fitting 62 although this structure does not prevent failure to attach the metal foil film 70 during manufacture. In some embodiments, the outer diameter D5 may be smaller than the outer diameter D2 of the bead 65.

[0083] In Embodiments 1 and 2, the metal foil film 70 is annular and flat. However, the metal foil film 70 may have another shape. As described above, the metal foil film 70 may be any brazing member placeable on the outer surface of the reinforcing plate 30A, 30B, or 40A to surround the through-hole 32, 33, 42, or 43. Thus, the metal foil film 70 may be replaced with another brazing member satisfying this condition.

[0084] FIG. 14 is a cross-sectional view of a rod-like brazing member 71 and a pipe fitting 62 used in a modification of the method for manufacturing the plate heat exchanger 1A according to Embodiment 1. FIG. 15 is a cross-sectional view of a brazing member 72 as a paste and a pipe fitting 62 used in another modification of the method for manufacturing the plate heat exchanger 1A according to Embodiment 1.

[0085] As illustrated in FIG. 14, the pipe fitting 62 may include a cylindrical larger-diameter portion 651 with larger inner and outer diameters than the basal end portion 66 and not insertable into the through-hole 33 in the reinforcing plate 30A. The larger-diameter portion 651 may have a recessed portion 652 at a comer adjacent to the basal end portion 66. In this structure, a brazing member 71 fittable into the recessed portion 652 may be used in place of the metal foil film 70 in the brazing process of the method for manufacturing the plate heat exchanger 1 A. As an example of the brazing member 71, the rod-like brazing member 71 with a circular cross section and a ring shape may be used. The brazing member 71 with this shape can be positioned in the recessed portion 652. The brazing member 71 with this shape can feed the brazing material to the gap between the basal end portion 66 of the pipe fitting 62 and the inner wall of the through-hole 33 from the surface of the reinforcing plate 30A opposite to the surface with the cladding 31, or more specifically, from the negative-X surface of the reinforcing plate 30A. The brazing member 71 may have a cross section with another shape such as a rectangle or an ellipse, rather than a circle.

[0086] As illustrated in FIG. 15, the pipe fitting 62 may have a larger-diameter portion 651 without the recessed portion 652 at the comer adjacent to the basal end portion 66. In this case, the brazing member 72 as a paste may be applied along the comer of the larger-diameter portion 651 adjacent to the basal end portion 66 in the brazing process of the method for manufacturing the plate heat exchanger 1 A. The brazing member 72 can also feed the brazing material to the gap between the basal end portion 66 of the pipe fitting 62 and the inner wall of the through-hole 33 from the negative-X surface of the reinforcing plate 30A, as in the structure illustrated in FIG. 14.

[0087] For the pipe fitting 62 illustrated in FIG. 15, the brazing member 72 as a paste may be replaced with the metal foil film 70 described in Embodiments 1 and 2.

[0088] To fully feed the brazing material to the gap between the basal end portion 66 of the pipe fitting 62 and the inner wall of the through-hole 33, the volume of the brazing member 71 or 72 may be greater than or equal to 25% of the volume of the gap between the basal end portion 66 of the pipe fitting 62 and the inner wall of the through-hole 33. The metal foil film 70 described in Embodiments 1 and 2 may also have a similar volume.

[0089] In Embodiments 1 and 2, the pipe fitting attachment process is performed after the metal foil attachment process. However, the method for manufacturing the plate heat exchanger 1A or IB is not limited to these examples. The method for manufacturing the plate heat exchanger 1A or IB may include (1) placing a brazing member on the outer surface of the outermost heat transfer plate to surround the through-holes 32 and 33 or 42 and 43, and (2) attaching a pipe to the outermost heat transfer plate by inserting a basal end portion of the pipe through the outer surface of the outermost heat transfer plate into the through-hole 32, 33, 42, or 43 to adjoin the larger-diameter portion to the outer surface of the outermost heat transfer plate. The method for manufacturing the plate heat exchanger 1A or IB may include the process (1) either followed by the process (2) or following the process (2).

[0090] The outermost heat transfer plate is a plate located outermost, of the plates typically referred to as heat transfer plates including the reinforcing plates 30A, 3 0B, and 40A and the heat transfer plates 10 and 20. The pipe is a tubular member, and examples of the pipe include the pipe fittings 61 to 64.

[0091] Thus, the metal foil attachment process and the pipe fitting attachment process described in Embodiments 1 and 2 and satisfying the above conditions may be performed in any order. When the brazing member 72 illustrated in FIG. 15 is used, for example, the metal foil attachment process, or more specifically, the pipe fitting attachment process may be followed by a process of placing the brazing member 72.

[0092] In Embodiments 1 and 2, the material of the metal foil film 70 is pure copper or a copper alloy. However, the material of the metal foil film 70 may be any brazing material. For example, the material of the metal foil film 70 may be pure aluminum or an aluminum alloy.

[0093] In Embodiments 1 and 2, the pipe fittings 61 to 64 are bonded to the reinforcing plates 30A or 3 0B and 40A. However, the method for manufacturing the plate heat exchanger 1A is not limited to this example. The pipe fittings 61 to 64 may be any pipes for a fluid to flow into and out of the flow space. For example, the pipe fittings 61 to 64 may be connection pipes, refrigerant pipes, or nozzles connectable to an external device.

[0094] In Embodiments 1 and 2, the pipe fittings 61 to 64 are manufactured by processing the ends of the pipes, and thus each have a pipe wall with a uniform thickness. However, the pipe fittings 61 to 64 are not limited to this example. As described above, the pipe fittings 61 to 64 may be any pipes for a fluid to flow into and out of the flow space, and thus may each have a pipe wall with a nonuniform thickness.

[0095] FIG. 16 is a cross-sectional view of a pipe fitting 62 in the plate heat exchanger 1A according to still another modification of Embodiment 1.

[0096] As illustrated in FIG. 16, the pipe fitting 62 manufactured by cutting may have the pipe wall at the distal end portion 68 and the bead 65 with a greater thickness than the pipe wall at the basal end portion 66. The pipe fitting 62 thus may have a pipe wall with a partially greater thickness than other parts.

[0097] In Embodiments 1 and 2, the basal end portion 66 of each of the pipe fittings 61 to 64 is swaged to temporarily fix the pipe fittings 61 to 64 to the reinforcing plates 30A or 30B and 40A. However, the method for manufacturing the plate heat exchanger 1A or IB is not limited to this example. In the method for manufacturing the plate heat exchanger 1A or IB, the process of attaching the pipe fittings 61 to 64 to the reinforcing plates 30A or 30B and 40A, or in other words, the process of attaching pipes to the outermost heat transfer plates may be any process including inserting the basal end portions of the pipes through the outer surfaces of the outermost heat transfer plates through the through-holes 32 and 33 or 42 and 43 and adjoining the beads 65 or the larger-diameter portions 651 to the outer surfaces of the outermost heat transfer plates.

[0098] Adjoining the bead 65 or the larger-diameter portion 651 to the outer surface of each outermost heat transfer plate may include adjoining the bead 65 or the larger-diameter portion 651 to the outer surface of the outermost heat transfer plate with a brazing member, or more specifically, the metal foil film 70 or the brazing member 71 or 72 held between the bead 65 or the larger-diameter portion 651 and the outer surface. In addition, the adjoining may include adjoining the bead 65 or the larger-diameter portion 651 to the outer surface of each outermost heat transfer plate without the metal foil film 70 or the brazing member 71 or 72 held between the bead 65 or the larger-diameter portion 651 and the outer surface.

[0099] Thus, the method for manufacturing the plate heat exchanger 1A or IB may or may not include swaging of the basal end portion 66 of each of the pipe fittings 61 to 64. For example, the pipe fittings 61 to 64 may be temporarily fixed to the reinforcing plates 30A or 30B and 40A by press fitting the basal end portions 66 of the pipe fittings 61 to 64 into the through-holes 33 in the reinforcing plates 30A or 30B and 40A.

[0100] In Embodiments 1 and 2, the pipe fittings 61 and 62 are connected to the reinforcing plate 30A with the cladding 31 having the same shape as the reinforcing plate 30A. In addition, the pipe fittings 63 and 64 are connected to the reinforcing plate 40A with the cladding 41 having the same shape as the reinforcing plate 40 A. However, the reinforcing plates 30A and 40A are not limited to these examples. In the method for manufacturing the plate heat exchanger 1A or IB, the outermost heat transfer plate may have the through-holes 32 and 33 or 42 and 43 for a fluid to flow into and out of the flow space and the brazing members located on the inner surface and surrounding the through-holes 32 and 33 or 42 and 43. Thus, the claddings 31 and 41 may not have the same shape as the reinforcing plates 30A and 40A. For example, the claddings 31 and 41 may be replaced with ring-shaped metal foil films located on the inner surface and surrounding the through-holes 32 and 33 or 42 and 43. The claddings 31 and 41 may be separate from the reinforcing plates 30A and 40A, rather than being integral with the reinforcing plates 30A and 40A through preliminary attachment. In this case, the pipe fittings 61 to 64 may be attached to the reinforcing plates 30A and 40A on which the claddings 31 and 41 are stacked.

[0101] As described above, the method for manufacturing the plate heat exchanger 1A or IB and the plate heat exchanger 1A or IB are not limited to the above embodiments, and may be modified or replaced in various manners. Various modifications of the present disclosure are described below as appendixes.

[0102] Appendix 1 A method for manufacturing a plate heat exchanger, the plate heat exchanger including a plurality of heat transfer plates stacked on one another with a flow space for a fluid defined between adjacent heat transfer plates of the plurality of heat transfer plates, at least an outermost heat transfer plate of the plurality of heat transfer plates having a through-hole through which the fluid flows into and out of the flow space, the outermost heat transfer plate including a first brazing member located on an inner surface of the outermost heat transfer plate and surrounding the through-hole, and a pipe through which the fluid flows into and out of the flow space, the pipe including a basal end portion and a larger-diameter portion having a larger outer diameter than the basal end portion, the basal end portion being brazed to an inner wall of the through-hole with the basal end portion extending through the through-hole and the larger-diameter portion adjoining an outer surface of the outermost heat transfer plate, the method comprising: placing a second brazing member on the outer surface of the outermost heat transfer plate to surround the through-hole; attaching the pipe to the outermost heat transfer plate by inserting the basal end portion of the pipe into the through-hole through the outer surface of the outermost heat transfer plate and adjoining the larger-diameter portion to the outer surface of the outermost heat transfer plate; and brazing the basal end portion of the pipe to the inner wall of the through-hole in the outermost heat transfer plate by heating the outermost heat transfer plate to which the pipe is attached and melting the first brazing member and the second brazing member. Appendix 2 The method according to appendix 1, wherein the second brazing member has a shape of a ring through which the basal end portion of the pipe is placeable. Appendix 3 The method according to appendix 2, wherein the placing the second brazing member includes placing the basal end portion of the pipe through an opening of the ring of the second brazing member before the attaching the pipe to the outermost heat transfer plate, and the attaching the pipe to the outermost heat transfer plate includes placing the second brazing member to surround the through-hole by inserting the basal end portion of the pipe into the through-hole until the second brazing member is held between the larger-diameter portion of the pipe and the outermost heat transfer plate. Appendix 4 The method according to appendix 3, wherein the second brazing member is foil, and the placing the second brazing member includes positioning the larger-diameter portion of the pipe with respect to the outermost heat transfer plate by holding the second brazing member between the larger-diameter portion and the outermost heat transfer plate. Appendix 5 The method according to any one of appendixes 2 to 4, wherein the second brazing member has an outer diameter larger than an outer diameter of the larger-diameter portion of the pipe, and the second brazing member has an inner diameter smaller than the outer diameter of the larger-diameter portion of the pipe and larger than an outer diameter of the basal end portion of the pipe. Appendix 6 The method according to any one of appendixes 1 to 4, wherein the first brazing member is a cladding layer comprising a brazing material and located on the inner surface of the outermost heat transfer plate. Appendix 7 The method according to any one of appendixes 1 to 6, wherein the larger-diameter portion of the pipe has a lager outer diameter than other portions including the basal end portion and a distal end portion of the pipe. Appendix 8 The method according to any one of appendixes 1 to 7, wherein the larger-diameter portion of the pipe has a greater thickness than the second brazing member in a direction in which the pipe extends. Appendix 9 The method according to any one of appendixes 1 to 8, wherein the outermost heat transfer plate has a recess on the outer surface, and the recess surrounds the through-hole, and the placing the second brazing member includes placing the second brazing member on the recess. Appendix 10 The method according to any one of appendixes 1 to 9, wherein the pipe includes a pipe portion adjacent to the larger-diameter portion, and the pipe portion is closer to a distal end of the pipe than the basal end portion, and the pipe portion has lower wettability with a brazing material than the larger-diameter portion, and the brazing material results from melting the first brazing member and the second brazing member. Appendix 11 A plate heat exchanger, comprising: a plurality of heat transfer plates stacked on one another with a flow space for a fluid defined between adjacent heat transfer plates of the plurality of heat transfer plates, an outermost heat transfer plate of the plurality of heat transfer plates having a through-hole through which the fluid flows into and out of the flow space, the outermost heat transfer plate including a first brazing member located on an inner surface of the outermost heat transfer plate and surrounding the through-hole; a pipe through which the fluid flows into and out of the flow space, the pipe including a basal end portion and a larger-diameter portion, the larger diameter portion being closer to a distal end of the pipe than the basal end portion and having a larger outer diameter than the basal end portion, the basal end portion being brazed to an inner wall of the through-hole with the basal end portion extending through the through-hole and the larger-diameter portion adjoining an outer surface of the outermost heat transfer plate; a second brazing member located on the outer surface of the outermost heat transfer plate and surrounding the through-hole; and a brazing material filling a gap between the outermost heat transfer plate and the larger-diameter portion of the pipe and a gap between the inner wall of the through-hole and the basal end portion of the pipe.

[0103] The foregoing describes some example embodiments for explanatory purposes. Although the foregoing discussion has presented specific embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the broader spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of the invention is defined only by the included claims, along with the full range of equivalents to which such claims are entitled.

[0104] This application claims the benefit of Japanese Patent Application No. 2022- 204852, filed on December 21, 2022, the entire disclosure of which is incorporated by reference herein. Reference Signs List

[0105] 1 A, IB Plate heat exchanger 10 Heat transfer pl ate 11 Upright wall 12 Inner fin 13 Metal foil film 14,15 Flow opening 16, 17 Communication opening 20 Heat transfer plate 21 Upright wall 22 Inner fin 23 Metal foil film 24, 25 Communication opening 26, 27 Flow opening 30A, 3 OB Reinforcing plate 31 Cladding 32,33 Through-hole 34,35 Fillet 36 Recess 37 Through-hole 40A Reinforcing plate 41 Cladding 42,43 Through-hole 50 Stack 61 to 64 Pipe fitting 65 Bead 66 Basal end portion 67 Groove 68 Distal end portion 70 Metal foil film 71,72 Brazing member 80 Punch 651 Larger-diameter portion 652 Recessed portion 653, 654 Flat surface 655, 656 Straight portion Al to A3 Arrow DI to D3 Outer diameter 5 D4 Inner diameter D5 Outer diameter D6 Diameter G Gap Tl, T2 Thickness

Claims

1. A method for manufacturing a plate heat exchanger, the plate heat exchanger includinga plurality of heat transfer plates stacked on one another with a flow space for a fluid defined between adjacent heat transfer plates of the plurality of heat transfer plates, at least an outermost heat transfer plate of the plurality of heat transfer plates having a through-hole through which the fluid flows into and out of the flow space, the outermost heat transfer plate including a first brazing member located on an inner surface of the outermost heat transfer plate and surrounding the through-hole, anda pipe through which the fluid flows into and out of the flow space, the pipe including a basal end portion and a larger-diameter portion having a larger outer diameter than the basal end portion, the basal end portion being brazed to an inner wall of the through-hole with the basal end portion extending through the through-hole and the larger-diameter portion adjoining an outer surface of the outermost heat transfer plate,the method comprising:placing a second brazing member on the outer surface of the outermost heat transfer plate to surround the through-hole;attaching the pipe to the outermost heat transfer plate by inserting the basal end portion of the pipe into the through-hole through the outer surface of the outermost heat transfer plate and adjoining the larger-diameter portion to the outer surface of the outermost heat transfer plate; andbrazing the basal end portion of the pipe to the inner wall of the through-hole in the outermost heat transfer plate by heating the outermost heat transfer plate to which the pipe is attached and melting the first brazing member and the second brazing member.[Claim 2J The method according to claim 1, whereinthe second brazing member has a shape of a ring through which the basal endportion of the pipe is placeable.

3. The method according to claim 2, whereinthe placing the second brazing member includes placing the basal end portion of the pipe through an opening of the ring of the second brazing member before the attaching the pipe to the outermost heat transfer plate, andthe attaching the pipe to the outermost heat transfer plate includes placing the second brazing member to surround the through-hole by inserting the basal end portion of the pipe into the through-hole until the second brazing member is held between the larger-diameter portion of the pipe and the outermost heat transfer plate.

4. The method according to claim 3, whereinthe second brazing member is foil, andthe placing the second brazing member includes positioning the larger-diameter portion of the pipe with respect to the outermost heat transfer plate by holding the second brazing member between the larger-diameter portion and the outermost heat transfer plate.

5. The method according to any one of claims 2 to 4, whereinthe second brazing member has an outer diameter larger than an outer diameter of the larger-diameter portion of the pipe, andthe second brazing member has an inner diameter smaller than the outer diameter of the larger-diameter portion of the pipe and larger than an outer diameter of the basal end portion of the pipe.

6. The method according to any one of claims 1 to 4, whereinthe first brazing member is a cladding layer comprising a brazing material andlocated on the inner surface of the outermost heat transfer plate.

7. The method according to any one of claims 1 to 6, wherein the larger-diameter portion of the pipe has a lager outer diameter than other portions including the basal end portion and a distal end portion of the pipe.

8. The method according to any one of claims 1 to 7, whereinthe larger-diameter portion of the pipe has a greater thickness than the second brazing member in a direction in which the pipe extends.

9. The method according to any one of claims 1 to 8, whereinthe outermost heat transfer plate has a recess on the outer surface, and the recess surrounds the through-hole, andthe placing the second brazing member includes placing the second brazing member on the recess.

10. The method according to any one of claims 1 to 9, whereinthe pipe includes a pipe portion adjacent to the larger-diameter portion, and the pipe portion is closer to a distal end of the pipe than the basal end portion, andthe pipe portion has lower wettability with a brazing material than the larger-diameter portion, and the brazing material results from melting the first brazing member and the second brazing member.

11. A plate heat exchanger, comprising:a plurality of heat transfer plates stacked on one another with a flow space for a fluid defined between adjacent heat transfer plates of the plurality of heat transfer plates, an outermost heat transfer plate of the plurality of heat transfer plates having a through-hole through which the fluid flows into and out of the flow space, the outermost heat transfer plate including a first brazing member located on an inner surface of the outermost heat transfer plate and surrounding the through-hole;a pipe through which the fluid flows into and out of the flow space, the pipe5 including a basal end portion and a larger-diameter portion, the larger diameter portion being closer to a distal end of the pipe than the basal end portion and having a larger outer diameter than the basal end portion, the basal end portion being brazed to an inner wall of the through-hole with the basal end portion extending through the through-hole and the larger-diameter portion adjoining an outer surface of the outermost heat transfer plate;10 a second brazing member located on the outer surface of the outermost heat transfer plate and surrounding the through-hole; anda brazing material filling a gap between the outermost heat transfer plate and the larger-diameter portion of the pipe and a gap between the inner wall of the through-hole and the basal end portion of the pipe.PCT / JP2023 / 023235A. CLASSIFICATION OF SUBJECT MATTER B23K J / W(2006.01)i; F2SF3 / W(2006.01)i; F28F ,W(2006.01 )i FI: F28F3 / 00 301A; B23K1 / 00 330J; F28F3 / 08 301Z According to International Patent Classification (IPC) or to both national classification and IPC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) B23K1 / 00; F28F3 / 00: F28F3 / 08; F28F9 / 26 Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched Published examined utility model applications of Japan 1922-1996 Published unexamined utility model applications of Japan 1971-2023 Registered utility model specifications of Japan 1996-2023 Published registered utility model applications of Japan 1994-2023 Electronic data base consulted during the international search (name of data base and, where practicable, search terms used) C. DOCUMENTS CONSIDERED TO BE RELEVANT Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. Y WO 00 / 00310 Al (ALFA LAVAL AB) 06 January 2000 (2000-01-06) p. 9, lines 13-27, fig. 1-2 1-11 Y Microfilm of the specification and drawings annexed to the request of Japanese Utility Model Application No. 183571 / 1987 (Laid-open No. 88187 / 1989) (SHOWA ALUMINUM CORP) 09 June 1989 (1989-06-09), specification, p. 8, line 8 to p. 9, line 16, p. 11, line 10 to p. 12, line 4, fig. 1-2 1-11 Y JP 2021-17935 A (RINNAIKK) 15 February 2021 (2021-02-15) paragraphs [0048]-[0050], fig. 3, 7 2-10 Y JP 5-318098 A (SHOWA ALUMINUM CORP) 03 December 1993 (1993-12-03) paragraph [0005], fig. 10 2-10 Y Y JP 2002-181486 A (DENSO CORP) 26 June 2002 (2002-06-26) paragraph [0021] JP 3-187128 A (HITACHI LTD) 15 August 1991 (1991-08-15) p. 3, upper left column, lines 4-19, fig. 1 6-10 9-10 | S | Further documents are listed in the continuation of Box C. | J | See patent family annex. * Special categories of cited documents: “T” later document published after the international filing date or priority “A” document defining the general state of the art which is not considered date and not in conflict with the application but cited to understand the to be of particular relevance principle or theory underlying the invention “E" earlier application or patent but published on or after the international -‘X” document of particular relevance; the claimed invention cannot be filing date considered novel or cannot be considered to involve an inventive step “L” document which may throw doubts on priority claim(s) or which is when the document is taken alone cited to establish the publication date of another citation or other “y document of particular relevance; the claimed invention cannot be special reason (as specified) considered to involve an inventive step when the document is “O” document referring to an oral disclosure, use, exhibition or other combined with one or more other such documents, such combination means being obvious to a person skilled in the ait “P” document published prior to the international filing date but later than document member of the same patent family the priority date claimed Date of the actual completion of the international search 16 August 2023 Date of mailing of the international search report 29 August 2023 Name and mailing address of the ISA / JP Japan Patent Office (ISA / JP) 3-4-3 Kasumigaseki, Chiyoda-ku, Tokyo 100-8915 Japan Authorized officer Telephone No.PCT / JP2023 / 023235C. DOCUMENTS CONSIDERED TO BE RELEVANTCategory* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No.Y Microfilm of the specification and drawings annexed to the request of Japanese Utility Model 10Application No. 100761 / 1983 (Laid-open No. 12096 / 1985) (NIHON RAJIETA KABUSHIKI KAISHA) 26 January 1985 (1985-01-26), specification, p. 4, line 5 to p. 5, line 7, fig. 4-5International application No.PCT / JP2023 / 023235Patent document cited in search report Publication date (day / month / year) Patent family member)s) Publication date (day / month / year) WO 00 / 00310 Al 06 January 2000 EP 1087851 Al DE 69919540 T2 JP 1-88187 UI 09 June 1989 (Family: none) JP 2021-17935 A 15 February 2021 (Family: none) JP 5-318098 A 03 December 1993 US 5975193 A column 1, lines 34-42, fig. 10 WO 2004 / 083745 Al JP 2002-181486 A 26 June 2002 (Family: none) JP 3-187128 A 15 August 1991 (Family: none) JP 60-12096 UI 26 January 1985 (Family: none)

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