Method for manufacturing plate stack unit for heat exchanger

Abstract

To provide a method of manufacturing a plate lamination body unit for heat exchanger capable of properly welding a pair of a terminal plates and a plate laminate body.SOLUTION: A method of manufacturing a plate lamination body unit for heat exchanger includes compression processes (S13, S15) for compressing a plate lamination body, a pair of terminal plates arranged on both sides in a lamination direction for the plate lamination body and a pair of restriction plates arranged on both sides in the lamination direction for the pair of terminal plates from both sides in the lamination direction by using a pressurizing tool, a welding process (S17) for welding a peripheral part of the plate lamination body and respective peripheral parts of the pair of terminal plate parts during execution of the compression processes (S13, S15), a connection process (S19) for connecting the pair of restriction plates to each other by using a connection tool after the welding process and a pressure releasing process (S21) for detaching the pressurizing tool after the connection process.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a plate stack unit for a heat exchanger. [Background technology]

[0002] The heat exchanger disclosed in Patent Document 1 houses a plate stack configured to perform heat exchange between a CO2 refrigerant and an NH3 refrigerant. The plate stack includes a plurality of plates welded together and a pair of terminal plates that sandwich the plurality of plates from both sides in the stacking direction. One of the pair of terminal plates illustrated in the document blocks the flow path of the CO2 refrigerant. The other terminal plate is provided with an inlet pipe and an outlet pipe. Both the inlet pipe and the outlet pipe communicate with the flow path of the CO2 refrigerant formed in the plate stack. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5690532 Summary of the Invention [Problem to be solved by the invention]

[0004] The peripheral edges of the pair of terminal plates and the peripheral edges of the plate stack need to be properly welded to prevent leakage of the CO2 refrigerant, but the above patent document does not disclose a specific method for proper welding.

[0005] An object of the present disclosure is to provide a method for manufacturing a plate stack unit for a heat exchanger that can properly weld a pair of terminal plates and a plate stack. [Means for solving the problem]

[0006] A method for manufacturing a plate stack unit for a heat exchanger according to at least one embodiment of the present disclosure includes: a compression step of compressing the plate stack, a pair of terminal plates disposed on both sides of the plate stack in the stacking direction, and a pair of restraint plates disposed on both sides of the pair of terminal plates in the stacking direction using a pressure jig from both sides in the stacking direction; a welding step for welding a peripheral edge of the plate stack to a peripheral edge of each of the pair of terminal plates during the compression step; a connecting step for connecting the pair of restraint plates to each other using a connecting tool after the welding step; a pressure releasing step for removing the pressure jig after the connecting step; Equipped with. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a method for manufacturing a plate stack unit for a heat exchanger, which can properly weld a pair of terminal plates and a plate stack. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a conceptual cross-sectional view of a heat exchanger according to one embodiment. [Figure 2] FIG. 2 is a conceptual exploded perspective view of a plate stack unit according to one embodiment. [Figure 3] 1 is a conceptual perspective view of a plate stack according to one embodiment; [Figure 4] FIG. 2 is a conceptual explanatory diagram of a plate stack unit according to one embodiment, viewed in the stacking direction. [Figure 5] 10 is a flowchart of a method for manufacturing a plate stack unit according to an embodiment. [Figure 6] 1A to 1C are conceptual explanatory diagrams of a method for assembling a pair of plates according to one embodiment. [Figure 7] FIG. 10 is a conceptual explanatory diagram of an arrangement process according to an embodiment. [Figure 8] FIG. 10 is a conceptual explanatory diagram of a fastening process according to an embodiment. [Figure 9] FIG. 10 is a conceptual explanatory diagram of a connecting step according to one embodiment. [Figure 10] 10A and 10B are conceptual explanatory diagrams of a plate stack before and after a pressure release step according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," or "have" one element are not exclusive expressions that exclude the presence of other elements. Note that the same components will be denoted by the same reference numerals and the description thereof will be omitted.

[0010] <1. Example of Overview of Heat Exchanger 30> 1 is a conceptual cross-sectional view of a heat exchanger 30 according to an embodiment of the present disclosure. The heat exchanger 30 is configured to exchange heat between a first heat medium T for circulating through a primary refrigerant circuit 10 and a second heat medium R for circulating through a secondary refrigerant circuit 20. An example of the first heat medium T is NH3 in a gas or liquid phase, and an example of the second heat medium R is CO2 in a liquid phase. The first heat medium T and the second heat medium R may be fluids other than those mentioned above.

[0011] The first heat medium liquid Te, which is the first heat medium T in liquid phase and flows into the heat exchanger 30, is transformed into a first heat medium gas Tv by heat obtained from the second heat medium R. That is, in the primary refrigerant circuit 10, the heat exchanger 30 functions as an evaporator for the first heat medium T. The flow state of the first heat medium T flowing into the heat exchanger 30 may be a gas-liquid two-phase flow. The first heat medium gas Tv flowing out of the heat exchanger 30 is transformed into the first heat medium liquid Te while circulating through the primary refrigerant circuit 10 and returns to the heat exchanger 30. The primary refrigerant circuit 10 includes a compressor, a condenser, an expansion valve, and the like. Meanwhile, the second heat medium R, which has been cooled by heat exchange with the first heat medium T, extracts cold while circulating through the secondary refrigerant circuit 20. The second heat medium R is heated and returns to the heat exchanger 30. The secondary refrigerant circuit 20 includes a receiver, a pump, a cooler, and the like. The cooler is configured to extract cold from the second heat medium R. For example, the cooler may be configured to perform heat exchange between the second heat medium R circulating through the secondary refrigerant circuit 20 and a heat medium such as air circulating inside the freezer.

[0012] The heat exchanger 30 in this example is a plate-type heat exchanger, more specifically a plate-and-shell heat exchanger. The heat exchanger 30 includes, for example, a container 35 having a reservoir of first heat transfer liquid Te formed therein, and a plate stack unit 100 immersed in the reservoir of first heat transfer liquid Te. The container 35 in this example is formed in a cylindrical shape extending in the stacking direction of the plate stacks 40 included in the plate stack unit 100. The container 35 is also provided with a discharge pipe 50 for discharging the first heat transfer liquid Te to the plate stack 40, and an exhaust duct 60 for discharging the first heat transfer gas Tv generated inside the container 35. The exhaust duct 60 is provided with a plurality of communication ports 63 through which the first heat transfer gas Tv can flow. In this example, the second heat medium R flows inside the plate stack 40 immersed in a pool of the first heat medium liquid Te, and heat exchange occurs between the first heat medium liquid Te and the second heat medium R. The first heat medium gas Tv generated by the heat exchange is discharged from the heat exchanger 30 via the exhaust duct 60.

[0013] 2. Example of the configuration of the plate stack unit 100 Fig. 2 is a conceptual exploded perspective view of a plate stack unit 100 according to an embodiment of the present disclosure. Fig. 3 is a conceptual perspective view of a plate stack 40 according to an embodiment of the present disclosure. Fig. 4 is a conceptual explanatory view of the plate stack unit 100 according to an embodiment of the present disclosure as viewed in the stacking direction.

[0014] 2, the plate stack unit 100 includes a plate stack 40 including a plurality of stacked plates 44. The stacking direction of the plate stack 40 substantially coincides with the thickness direction of each plate 44. The plate stack unit 100 further includes a pair of terminal plates 110 arranged on either side of the plate stack 40 in the stacking direction, a pair of constraint plates 120 arranged on either side of the pair of terminal plates 110 in the stacking direction, and a connector 130 that connects the pair of constraint plates 120 to each other.

[0015] As shown in FIGS. 2 and 3 , each of the multiple plates 44 of the plate stack 40 has a first communication opening 41 and a second communication opening 42. The first communication opening 41 and the second communication opening 42 both form part of the second flow path 32, which is a flow path for the second heat medium R. A plurality of linearly extending uneven portions 43 are formed on the wall surface of each plate 44. The uneven portions 43 are formed by press working, for example, and the uneven portions 43 formed on one side are convex portions, while the uneven portions 43 formed on the other side are concave portions. Furthermore, it is understood that the spaces between the multiple convex portions corresponding to the multiple convex portions 43 formed on one side are concave portions. In accordance with the same concept, it is understood that the spaces between the multiple concave portions corresponding to the multiple convex portions 43 formed on the other side are convex portions.

[0016] As shown in FIG. 3 , the plate stack 40 includes a plurality of sets of pair plates 47, each formed of a pair of plates 44. In each pair of plates 44, the peripheral edges of the two first communication openings 41 are welded to each other, and the peripheral edges of the two second communication openings 42 are welded to each other. Since the outer peripheral edges 49 of each pair of plates 44 are not welded, a first flow path 31, which is a flow path for the first heat medium T, is formed between the pair of plates 44. The inner spaces of the first communication opening 41 and the second communication opening 42 are separated from the first flow path 31 by welds formed on the peripheral edges of the first communication opening 41 and the second communication opening 42. The pair of plates 44 constituting each pair of plates 47 are arranged so that the convex portions of the concave-convex portions 43 face each other. The pair of plates 44 are pressed (compressed) against each other so that the uneven portions 43 are in close contact with each other, thereby increasing the flow path length of the first flow path 31 and promoting heat exchange between the first heat medium T and the second heat medium R.

[0017] Two pairs of plates 47 adjacent to each other in the stacking direction are welded to each other at their outer peripheral edges 49. This forms a second flow path 32 for the second heat medium R between the pair of plates 47, which is separated from the internal space of the container 35.

[0018] The first communication opening 41 on one side of the plate stack 40 in the stacking direction communicates with the inlet pipe 7, and the second communication opening 42 communicates with the outlet pipe 6. Furthermore, the peripheral edge 49 of each plate 44 in this embodiment has a first peripheral edge 71 formed in an arc shape and a second peripheral edge 72 with a smaller curvature than the first peripheral edge 71. As a result, when viewed in the stacking direction, each plate 44 has a longitudinal direction and a lateral direction. The second peripheral edge 72 is longer in the longitudinal direction than the first peripheral edge 71 and is positioned above the first peripheral edge 71. Therefore, the first heat transfer liquid Te discharged from the discharge pipe 50 is more likely to hit each plate 44, promoting heat exchange between the first heat transfer medium T and the second heat transfer medium R. The second peripheral edge 72 may be curved or flat. On the other hand, the first peripheral edge portion 71 disposed on the lower side does not necessarily have to have a shape that makes it easy for the discharged first heat medium liquid Te to hit it. Furthermore, the smaller the gap between the first peripheral edge portion 71 and the inner wall surface of the container 35, the larger the plates 44 can be, and the more efficient the heat exchange between the first heat medium T and the second heat medium R can be. Therefore, it is preferable that the first peripheral edge portion 71 be formed in an arc shape that follows the cylindrical shape of the container 35. Note that in other embodiments, each plate 44 may be formed in a circular or elliptical shape.

[0019] Returning to FIG. 2 , the pair of terminal plates 110 each have approximately the same outer shape as the plurality of plates 44. The pair of terminal plates 110 are welded to a pair of plates 44 that are located outermost in the stacking direction among the plurality of plates 44. As a more specific example, the peripheral edge 49 of each plate 44 is welded to the peripheral edge 119 of each terminal plate 110 over the entire circumferential length. In addition, the inlet pipe 7 and the outlet pipe 6 are joined to the terminal plate 110 located on one side in the stacking direction. As described above, the inlet pipe 7 and the outlet pipe 6 are connected to the first communication opening 41 and the second communication opening 42, respectively, of the plate 44 located on the other side.

[0020] The restraint plate 120 shown in FIGS. 2 and 4 has a first opening 121 and a second opening 122, inside which the inlet pipe 7 and the outlet pipe 6 are respectively arranged (the terminal plate 110 is not shown in FIG. 4). A peripheral edge 129 of the restraint plate 120 is formed to surround the peripheral edge 49 of the plate stack 40 when viewed in the stacking direction. In other words, when viewed in the stacking direction, the peripheral edge 129 is located outside the peripheral edge 49 along the entire circumferential length of the peripheral edge 129. The connectors 130 are bars extending in the stacking direction. In this example, both ends of each of the multiple connectors 130 are welded to the peripheral edges 129 of the pair of restraint plates 120. Because the peripheral edge 129 is located outside the peripheral edge 49 when viewed in the stacking direction, all of the multiple connectors 130 are spaced apart from the plate stack 40 and the pair of terminal plates 110.

[0021] As described above, the plate stack 40 is arranged in a compressed state, and at least a portion of the plate stack 40 is elastically deformed in the stacking direction. The pair of restraint plates 120 and connectors 130 prevent the compressed plate stack 40 from restoring to its original shape. In other words, tensile stress caused by the restoring force of the plate stack 40 acts on the multiple connectors 130. Note that a portion of the compressed plate stack 40 may be plastically deformed.

[0022] 3. Example of the method for manufacturing the plate stack unit 100 FIG. 5 is a flowchart showing a method for manufacturing a plate stack unit 100 for a heat exchanger according to an embodiment of the present disclosure (in the following description, "step" may be abbreviated as "S"). FIG. 6 is a conceptual explanatory diagram of a method for assembling a pair of plates 47 according to an embodiment of the present disclosure. FIG. 7 is a conceptual explanatory diagram of an arrangement step according to an embodiment of the present disclosure. FIG. 8 is a conceptual explanatory diagram of a fastening step according to an embodiment of the present disclosure. FIG. 9 is a conceptual explanatory diagram of a connection step according to an embodiment of the present disclosure.

[0023] As shown in FIG. 5, first, an assembly process of the plate stack 40 is performed (S11). For example, as shown in FIG. 6, the peripheral portions of the first communication openings 41 of a pair of plates 44 are welded to each other, and the peripheral portions of the second communication openings 42 of each pair of plates 44 are welded to each other. This completes the pair of plates 47. At this time, the concave-convex portions 43 of each pair of plates 44 do not need to be in close contact with each other. The process of fabricating the pair of plates 47 is repeated to prepare multiple sets of pair of plates 47. Thereafter, as shown in FIG. 3, the process of welding the peripheral portions 49 of each set of pair of plates 47 is repeated. This completes the assembly of the plate stack 40.

[0024] Returning to FIG. 5, various parts required for manufacturing the plate stack unit 100 are arranged (S13). For example, as shown in FIG. 7, a pressure jig 200 for compressing the plate stack unit 100 is prepared. The pressure jig 200 includes a pair of pressure tables 210, a plurality of fastening shafts 220 (see FIG. 8), and a plurality of nuts (not shown). On one pressure table 210 arranged on the lower side, a constraint plate 120, a terminal plate 110, the plate stack 40, the terminal plate 110, and the constraint plate 120 are placed in this order from the bottom. The other pressure table 210 is then arranged above the constraint plate 120. As a result, the plate stack 40, the pair of terminal plates 110, the pair of constraint plates 120, and the pair of pressure tables 210 are arranged in this order from the inside in the stacking direction (from the center side in the stacking direction of the plate stack 40).

[0025] The peripheral edge of the pressure table 210 surrounds the pair of restraint plates 120 when viewed in the stacking direction. In other words, when viewed in the stacking direction, the peripheral edge of the pressure table 210 is located outside the peripheral edge 129 of the restraint plate 120 along its entire circumferential length. The pressure table 210 also has a plurality of insertion holes 212. Each of the insertion holes 212 is located outside the peripheral edge 129 of the pair of restraint plates 120 when viewed in the stacking direction. In other words, each insertion hole 212 is positioned to avoid the plate stack 40, the pair of terminal plates 110, and the pair of restraint plates 120 in the stacking direction. The insertion holes 212 are open in the stacking direction and also open in a horizontal direction perpendicular to the stacking direction. Furthermore, two of the insertion holes 212, insertion holes 212A, are positioned with both longitudinal ends of the plate 44 between them when viewed in the stacking direction.

[0026] Returning to FIG. 5 , a fastening step is performed in which the pair of pressure tables 210 of the pressure jig 200 are fastened together (S15). For example, as shown in FIG. 8 , a plurality of fastening shafts 220 are inserted into each of the plurality of insertion holes 212. Male threads are formed on the outer peripheries of the fastening shafts 220, and a plurality of nuts (not shown) are attached to the upper ends of the inserted plurality of fastening shafts 220. Each nut is fastened so as to be pressed against the pressure table 210 from above. This applies a pressure force to the upper pressure table 210, fastening the pair of pressure tables 210 together. In other words, the pair of pressure tables 210 apply a compressive force to the plate stack 40 via the pair of constraint plates 120 and the pair of terminal plates 110. As a result, the plate stack 40 is compressed, and the concave-convex portions 43 of the two plates 44 constituting the pair of plates 47 come into close contact with each other. Furthermore, the pair of constraint plates 120 move closer to each other as the plate stack 40 is compressed.

[0027] The contact positions between the peripheries of the insertion holes 212 and the nuts are input points P to which pressure is applied. In this example, there are six input points P. The input points P are positioned so as to surround the plate stack 40 when viewed in the stacking direction. At least two of the input points P on the upper pressure table 210 have different pressure forces. In other words, at least two of the input points P have different tightening amounts for the nuts. The advantages of different pressure forces will be described later.

[0028] Additionally, when the fastening shaft 220 is inserted into the insertion hole 212 along the vertical direction, the greater the length of the plate stack 40 in the stacking direction, the more likely it is that the ease of insertion will decrease. In this regard, since each insertion hole 212 in this embodiment is open horizontally, the fastening shaft 220 can be inserted into the insertion hole 212 along the horizontal direction. Therefore, even if the plate stack 40 is long in the stacking direction, the ease of insertion will not be impaired.

[0029] 5 and 8, a welding process is performed (S17) to weld the peripheral edge 49 of the plate stack 40 to the peripheral edge 119 of each of the pair of terminal plates 110. At this time, because pressure is applied by the pressure jig 200, the peripheral edges 49, 119 are in close contact with each other over their entire circumferential length. Welding is performed on these intimately contacted peripheral edges 49, 119. Therefore, the welded portion 150 is properly finished over its entire circumferential length.

[0030] 5 and 9, a connecting step is then carried out in which the pair of constraint plates 120 are connected to each other by connectors 130 (S19). In the example of FIG. 9, both ends of each of the multiple connectors 130 extending in the stacking direction are connected by welding to the peripheral edges 129 of the pair of constraint plates 120. In this way, the plate stack unit 100 is assembled in a state where it is pressed by the pressing jig 200.

[0031] Returning to FIG. 5, a pressure release step is performed in which the pressing jig 200 is removed (S21). More specifically, the multiple nuts are removed from the multiple fastening shafts 220, respectively. This completes the compression using the pressing jig 200, but the plate stack 40 remains constrained in a compressed state by the pair of restraint plates 120 and connectors 130. Therefore, even after the compression using the pressing jig 200 is completed, the plate stack 40 maintains its compressed state with almost no recovery. Thereafter, the multiple fastening shafts 220 and the upper pressing table 210 are removed, and the plate stack unit 100 is taken out. This completes the manufacture of the plate stack unit 100. The portable plate stack unit 100 is then housed in the container 35 of the heat exchanger 30.

[0032] According to the above configuration, by performing the compression steps S13 and S15, in which the plate stack 40, the pair of terminal plates 110, and the pair of restraint plates 120 are compressed from both sides in the stacking direction by the pressure jig 200, the peripheral edge 49 of the plate stack 40 and the peripheral edge 119 of the pair of terminal plates 110 can be tightly attached to each other along their entire circumferential length. Since the welding step (S17) is performed with the peripheral edges 49, 119 in tight contact, these peripheral edges 49, 119 can be properly welded along their entire circumferential length. Furthermore, since the peripheral edges 49, 119 are welded before the connecting step (S19), the connecting tool 130 does not interfere with the welding step (S17). As described above, a method for manufacturing a plate stack unit 100 for a heat exchanger can be realized, which allows the plate stack 40 and the pair of terminal plates 110 to be easily and properly welded together. Furthermore, even after the pressure releasing step (S21) is performed, the connector 130 prevents the compressed plate stack 40 from returning to its original shape, thereby suppressing tensile stress at the welded joint 150. More specifically, even if a large force is generated that separates the plate stack 40 and the terminal plate 110 due to the second heat medium R as a high-pressure fluid flowing through the second flow path 32 of the plate stack 40, the connector 130 receives this force, thereby suppressing tensile stress at the welded joint 150. Thus, a method for manufacturing a plate stack unit 100 for a heat exchanger that can be adapted for use in the heat exchanger 30 is realized.

[0033] Furthermore, in the fastening step (S15), the pair of pressure tables 210 are fastened using the multiple fastening shafts 220 included in the pressure jig 200 at each of multiple positions (multiple input points P in this embodiment) that avoid the plate stack 40, the pair of terminal plates 110, and the pair of constraint plates 120 when viewed in the stacking direction. According to the above configuration, the pair of pressure tables 210 are fastened in a state in which the multiple fastening shafts 220 are spaced apart from the plate stack 40, the terminal plates 110, and the pair of constraint plates 120. As a result, the multiple fastening shafts 220 do not get in the way when the post-welding step (S17) is performed after the fastening step. This facilitates the welding step.

[0034] Furthermore, in the connecting step (S19), peripheral portions 129 of a pair of constraint plates 120 formed to surround the plate stack 40 when viewed in the stacking direction are connected using connectors 130. According to the above configuration, because peripheral portions 129 of the constraint plates 120 are formed to surround the plate stack 40 when viewed in the stacking direction, connectors 130 are connected to the pair of constraint plates 120 at a distance from the plate stack 40. Therefore, the plate stack 40 does not get in the way when the connecting step (S19) is performed, and the connecting step (S19) can be facilitated.

[0035] The plate stack 40 includes a plurality of plates 44 on which concave-convex portions 43 are formed, which become the first flow paths 31 and the second flow paths 32. In steps S13 and S15, which correspond to the compression steps described above, the concave-convex portions 43 of two adjacent plates 44 in the stacking direction among the plurality of plates 44 are brought into close contact with each other. According to the above configuration, even after the pressure release step (S21) is performed, the pair of plates 44 and the connector 130 prevent the plate stack 40 from returning to its original state, so that the concave-convex portions 43 of the two adjacent plates 44 can maintain contact with each other. This increases the flow path length of the first flow paths 31, thereby facilitating heat exchange in the plate stack 40.

[0036] <4. Example of the advantage of varying pressure depending on input point P> 9 and 10, the advantage of the pressure applied in the fastening step (S15) varying depending on the input point P will be illustrated. Fig. 10 is a conceptual explanatory diagram of the plate stack 40 before and after the pressure release step (S21) according to an embodiment of the present disclosure. For ease of understanding, Fig. 10 conceptually illustrates only two input points P of the pressure applied by the pressure jig 200.

[0037] 10, when the pressure is released as the pressure release step is performed, the plate stack 40 slightly restores its original shape in the stacking direction despite being constrained by the pair of restraint plates 120 and the connectors 130. The restoration amount in the stacking direction is 1% or less of the length of the plate stack 40 in the stacking direction, more specifically, 0.5% or less.

[0038] However, even if the restoration amount is small, the plate stack 40 may tilt as the pressure release step is performed. The reason for this tilt is as follows.

[0039] The strain generated inside the plate stack 40 as a result of the fastening step (S15) is unevenly distributed within the plate stack 40. This is thought to be due to factors such as the fact that the multiple plates 44 of the plate stack 40 are not strictly identical in shape and that there are differences in the arrangement pattern (e.g., density) of the multiple concave-convex portions 43 within a single plate 44. In particular, if the density of the concave-convex portions 43 within a single plate 44 is uneven, the amount of strain contained within that plate 44 will be uneven. As a result, when a uniform pressure is applied to the plate stack 40, the amount of restoration of the plate stack 40 confirmed by performing the pressure release step (S21) will not be uniform, the stacking direction of the plate stack 40 will change, and the plate stack 40 will tilt. According to the inventors' findings, the direction of tilt is determined by the respective positions of the multiple input points P, the shape of the plate stack 40, the arrangement pattern of the concave-convex portions 43, the shape of each concave-convex portion 43, and the like. In the example at the top of Figure 10, even if an even pressure is applied during the fastening process, a relatively large strain (relatively large compression) appears on one side of the plate stack 40 (the left side in the example of Figure 10). As a result, the amount of recovery of the plate stack 40 due to the pressure release process is large on one side of the plate stack 40, and the tilt of the plate stack 40 increases as the pressure release process is performed. In the example of Figure 10, the dimension L2 is larger than the dimension L1. Note that the dimension L1 may be zero.

[0040] In this embodiment, in the fastening step (S15), taking into account that the restoration amount in the stacking direction is not uniform, adjustment is performed to vary the pressure force at at least two of the multiple input points P (lower part of FIG. 10 ). As a result, the pressure force on one side, which tends to have a larger restoration amount, increases, thereby increasing the amount of elastic deformation at one side of the plate stack 40. The connecting step (S19) is performed in the fastened state after adjusting the amount of elastic deformation, and the state of the plate stack 40, in which there is a deviation in the amount of elastic deformation, is maintained (constrained) by the connector 130. Therefore, when the pressure release step (S21) is performed, the restoration amount at one side of the plate stack 40 is reduced by the adjusted amount of elastic deformation because it is constrained by the connector 130. Therefore, the restoration amount of the plate stack 40 is uniform. In the example of FIG. 10 , the dimension L4 is smaller than the dimension L2, and tilt of the plate stack 40 is suppressed. Therefore, a plate stack unit 100 with suppressed tilt can be manufactured. In addition, the uniform amount of restoration that occurs in the plate stack 40 when the pressure is different and the unequal amount of restoration that occurs in the plate stack 40 when the pressure is equal are both 1% or less of the stacking direction length of the plate stack 40, more specifically 0.5% or less.

[0041] As described above, it is preferable that the gap between the inner wall surface of the container 35 of the heat exchanger 30 and the plate stack 40 housed in the container 35 is small. In this regard, since tilting of the plate stack 40 is suppressed, variation in the outer dimensions of the plate stack 40 can be suppressed, and a plate stack 40 with a small gap can be manufactured. In other words, since the plate stack 40 housed in the container 35 having the specified dimensions can be made large, it is possible to realize a heat exchanger 30 that promotes heat exchange between the first heat medium T and the second heat medium R in the heat exchanger 30.

[0042] 8, the at least two input points P having different pressure forces include a pair of input points Pc. The pair of input points Pc is located on both sides of the plate 44 in the longitudinal direction of the plate stack 40 when viewed in the stacking direction. According to the inventors' findings, strain generated in the plate stack 40 as the fastening step (S15) is performed tends to be uneven in the longitudinal direction of the plates 44. With the above configuration, the compressive force applied to both longitudinal ends of each of the multiple plates 44 becomes uneven, thereby effectively suppressing tilt of the plate stack 40 after the pressure releasing step (S21) is performed.

[0043] In other embodiments, the pressure may be different at two or more input points P other than the pair of input points Pc among the plurality of input points P. Furthermore, by knowing in advance the tendency of uneven distribution of strain in the plate stack 40 when a uniform pressure force is applied to the plate stack 40 (the tendency of uneven distribution of the recovery amount in the plate stack 40), it becomes clear how to make the pressure force uneven at the plurality of input points P. As a result, it is possible to more effectively suppress tilting of the plate stack 40 after the pressure release step (S21) is executed.

[0044] <5. Summary> The contents of the above-described embodiments can be understood, for example, as follows.

[0045] 1) A method for manufacturing a plate stack unit (100) for a heat exchanger according to at least one embodiment of the present disclosure includes the steps of: a compression step (S13, S15) for compressing the plate stack (40), a pair of terminal plates (110) arranged on both sides of the plate stack (40) in the stacking direction, and a pair of restraint plates (120) arranged on both sides of the pair of terminal plates (110) in the stacking direction using a pressure jig (200) from both sides in the stacking direction; a welding step (S17) for welding a peripheral edge portion (49) of the plate stack (40) to a peripheral edge portion (119) of each of the pair of terminal plates (110) during the compression steps (S13, S15); After the welding step (S17), a connecting step (S19) is performed to connect the pair of restraint plates (120) to each other using a connecting tool (130); After the connecting step, a pressure releasing step (S21) is performed to remove the pressure jig (200). Equipped with.

[0046] According to the above configuration 1), the compression steps (S13, S15) allow the peripheral edge portion (49) of the plate stack (40) and the peripheral edge portions (119) of the pair of terminal plates (110) to be tightly attached to each other over their entire circumferential length. Since the welding step (S17) is performed with these peripheral edges (49, 119) in tight contact, the peripheral edge portion (49) of the plate stack (40) and the peripheral edge portions (119) of the pair of terminal plates (110) can be properly welded to each other over their entire circumferential length. Furthermore, since these peripheral edges (49, 119) are welded before the connecting step (S19) is performed, the connector (130) does not interfere with the welding step (S17). As described above, a method for manufacturing a plate stack unit (100) for a heat exchanger can be achieved, which allows the plate stack (40) and the pair of terminal plates (110) to be easily and properly welded to each other. Furthermore, even after the pressure release step (S21) is performed, the connectors (130) prevent the compressed plate stack (40) from returning to its original shape, thereby suppressing tensile stress at the welded portion (150) that occurs during the welding step (S17). For example, even if a large force that separates the plate stack (40) and the terminal plate (110) is generated due to the high-pressure fluid (second heat medium R) flowing through the flow path (second flow path 32) of the plate stack (40), the connectors (130) receive this force, thereby suppressing tensile stress at the welded portion (150). This realizes a method for manufacturing a plate stack unit (100) for a heat exchanger that can be used in the heat exchanger (30).

[0047] 2) In some embodiments, a method for manufacturing the plate stack unit (100) for a heat exchanger described in 1) above, comprising the steps of: In the compression steps (S13, S15), the pressure forces are different from each other at at least two of the multiple pressure input points (P) of the pressure jig (200) positioned to surround the plate stack (40) when viewed in the stacking direction.

[0048] The strain generated in the plate stack (40) during the compression steps (S13, S15) tends to occur unevenly. In this case, the amount of restoration in the stacking direction of the plate stack (40) that occurs when the pressure release step (S21) is performed is not uniform. Therefore, when the pressure release step (S21) is performed, the stacking direction of the plate stack (40) changes, and the plate stack (40) tends to tilt. In this regard, according to the configuration of 2) above, the pressure applied in the compression steps (S13, S15) is made different at at least two of the multiple input points (P) in consideration of the fact that the amount of restoration in the stacking direction is not uniform. Therefore, a relatively large compressive force is applied to the portion of the plate stack (40) known to have a large amount of restoration. Then, the connecting step (S19) is performed in the fastened state adjusted to increase the amount of elastic deformation in that portion, and the plate stack (40) is maintained in a state in which there is a deviation in the amount of elastic deformation. As a result, the amount of restoration of the portions that tend to have large amounts of elastic deformation is reduced during the pressure release step (S21), and the amount of restoration of the plate stack (40) is uniform. This makes it possible to manufacture a plate stack unit (100) with reduced tilt. This reduces variations in the external dimensions of the plate stack (40), allowing the plate stack (40) to be accommodated in the container (35) of the heat exchanger (30) with specified dimensions to be larger, thereby achieving a heat exchanger (30) that promotes heat exchange.

[0049] 3) In some embodiments, a method for manufacturing the plate stack unit (100) for a heat exchanger described in 2) above, comprising the steps of: The plate stack (40) includes a plurality of plates (44), Each of the plurality of plates (44) has a first peripheral edge portion (71) having an arcuate shape and a second peripheral edge portion (72) having a curvature smaller than that of the first peripheral edge portion, The at least two input points (P) at which the pressure forces differ from each other are located on both sides of the plate (44) in the longitudinal direction of the plate stack (40) when viewed in the stacking direction.

[0050] According to the findings of the inventors, the strain generated in the plate stack (40) as a result of the execution of the compression steps (S13, S15) tends to be uneven in the longitudinal direction of the plates (44). According to the configuration of 3) above, the compressive force applied to both longitudinal ends of each of the plurality of plates (44) becomes uneven, so that it is possible to effectively suppress tilting of the plate stack (40) after the pressure release step (S21) is executed.

[0051] 4) In some embodiments, a method for manufacturing the plate stack unit (100) for a heat exchanger according to any one of 1) to 3) above, comprising the steps of: The compression steps (S13, S15) are as follows: an arrangement step (S13) of arranging a pair of pressurizing tables (210) included in the pressurizing jig (200) on both sides of the pair of restraint plates (120) in the stacking direction; a fastening step (S15) for fastening the pair of pressurizing tables (210) using a plurality of fastening shafts (220) included in the pressurizing jig (200) at each of a plurality of positions avoiding the plate stack (40), the pair of terminal plates (110), and the pair of restraint plates (120) when viewed in the stacking direction; Includes:

[0052] According to the configuration 4), the pair of pressure tables 210 are fastened in a state in which the multiple fastening shafts 220 are spaced apart from the plate stack 40, the terminal plate 110, and the pair of restraint plates 120. This prevents the multiple fastening shafts 220 from getting in the way when the welding step S17, which is performed after the fastening step S15, is performed. This facilitates the welding step S17.

[0053] 5) In some embodiments, a method for manufacturing a plate stack unit (100) for a heat exchanger according to any one of 1) to 4) above, comprising the steps of: In the connecting step (S19), the peripheral portions (129) of the pair of restraint plates (120) formed so as to surround the plate stack (40) when viewed in the stacking direction are connected using the connectors (130).

[0054] According to the configuration of 5) above, the peripheral edge portion 129 of the restraint plate 120 is formed so as to surround the plate stack 40 when viewed in the stacking direction, so that the connector 130 is connected to the pair of restraint plates 120 at a distance from the plate stack 40. Therefore, the plate stack 40 does not get in the way when the connecting step S19 is performed, which makes the connecting step S19 easier.

[0055] 6) In some embodiments, a method for manufacturing the plate stack unit (100) for a heat exchanger according to any one of 1) to 5) above, comprising the steps of: The plate stack (40) includes a plurality of plates (44) each having a concave-convex portion (43) that serves as a flow path (first flow path 31) for a fluid (first heat medium), In the compression steps (S13, S15), the concave-convex portions (43) of two adjacent plates (44) in the stacking direction among the plurality of plates (44) are brought into close contact with each other.

[0056] According to the configuration 6), even when the pressure releasing step (S21) is performed, the pair of restraint plates (120) and the connector (130) prevent the plate stack (40) from restoring its original shape, so that the concave-convex portions (43) of two plates adjacent in the stacking direction can maintain contact with each other. This increases the length of the flow path (first flow path 31) of the fluid (first heat medium T), thereby facilitating heat exchange in the plate stack (40). [Explanation of symbols]

[0057] 30: Heat exchanger 40: Plate stack 43: Uneven part 44: Plate 49, 119: Periphery 71: First peripheral part 72: Second peripheral part 100: Plate laminate unit 110: Terminal plate 120: Restraint plate 129: Periphery 130: Connector 200: Pressure jig 210: Pressure table 220: Fastening shaft P, Pc: Input point

Claims

1. a compression step of compressing the plate stack, a pair of terminal plates disposed on both sides of the plate stack in the stacking direction, and a pair of restraint plates disposed on both sides of the pair of terminal plates in the stacking direction using a pressure jig from both sides in the stacking direction; a welding step for welding a peripheral edge of the plate stack to a peripheral edge of each of the pair of terminal plates during the compression step; a connecting step for connecting the pair of restraint plates to each other using a connecting tool after the welding step; a pressure releasing step for removing the pressure jig after the connecting step; A method for manufacturing a plate stack unit for a heat exchanger comprising:

2. In the compression step, the pressure applied by the pressure jig positioned so as to surround the plate stack as viewed in the stacking direction is different from each other at least two of a plurality of pressure application points. A method for manufacturing the plate stack unit for a heat exchanger according to claim 1.

3. The plate stack includes a plurality of plates, Each of the plurality of plates has a first peripheral edge portion that is arcuate and a second peripheral edge portion that has a curvature smaller than that of the first peripheral edge portion; The at least two input points at which the pressure forces are different from each other are located on both sides of the plate stack in the longitudinal direction of the plate when viewed in the stacking direction. A method for manufacturing the plate stack unit for a heat exchanger according to claim 2.

4. The compression step an arrangement step of arranging a pair of pressurizing tables included in the pressurizing jig on both sides of the pair of restraint plates in the stacking direction; a fastening process for fastening the pair of pressure tables using a plurality of fastening shafts included in the pressure jig at each of a plurality of positions avoiding the plate stack, the pair of terminal plates, and the pair of restraint plates when viewed in the stacking direction; 4. A method for manufacturing a plate stack unit for a heat exchanger according to claim 1, comprising:

5. In the connecting step, the peripheral portions of the pair of restraint plates formed so as to surround the plate stack as viewed in the stacking direction are connected by the connecting tool. A method for manufacturing the plate stack unit for a heat exchanger according to any one of claims 1 to 4.

6. the plate stack includes a plurality of plates on which concave and convex portions serving as fluid flow paths are formed, In the compression step, the concave and convex portions of two adjacent plates in the stacking direction among the plurality of plates are brought into close contact with each other. A method for manufacturing the plate stack unit for a heat exchanger according to any one of claims 1 to 5.

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