Brazing structure, heat exchanger, and method for manufacturing brazing structure

Abstract

To provide a brazing connection structure capable of appropriately performing brazing by a simple structure, and a heat exchanger and a manufacturing method of the brazing connection structure. A brazing connection structure includes: a first member (70) of which a part is formed as a flange portion (71) of a cylindrical shape as a press working portion; a second member (5) having a cylindrical portion (52) embedded in the flange portion (71) and connected to the first member (70); and a brazing portion (3) in which a filler metal (30) enters between an inner peripheral surface of the flange portion (71) and an outer peripheral surface of the cylindrical portion (52), and in the brazing connection structure, the flange portion (71) is formed as a polygonal cylindrical shape in which the cylindrical portion (52) is inscribed, and the brazing portion (3) is configured as a gap (90) in which the filler metal (30) enters between an inner surface portion of each corner portion (71a) of the flange portion (71) and the outer peripheral surface of the cylindrical portion (52).

Description

Technical Field

[0001] The present invention relates to a brazing connection structure for applications such as brazing the components of a heat exchanger for a hot water supply device, and related technologies, and more particularly to a brazing connection structure, a heat exchanger, and a method for manufacturing the brazing connection structure. Background Technology

[0002] As a specific example of a heat exchanger, the applicant previously proposed the content described in Patent Document 1.

[0003] In the heat exchanger described in the document, a plurality of heat transfer tubes are arranged inside the shell to which combustion gas is supplied. The ends of each heat transfer tube are led out to the outside of the side portion of the shell and connected to a manifold for hot water inflow or outflow.

[0004] Here, the manifold section is, for example, as shown below. Figure 11 The structure shown. That is, Figure 11 The manifold section 7e shown includes a pair of manifold body members 70e and 70a that form a chamber 72 for hot water inflow inside, and a joint member 5e that is brazed to one of the manifold body members 70e. Symbol 6 indicates a heat transfer tube.

[0005] As a means of brazing the connector member 5e to the manifold body member 70e, the following means are used: a flange hole 74e is provided on the manifold body member 70e, and the cylindrical part 52 on the front end side of the connector member 5e is inserted into the cylindrical flange part 71e, and then the components are brazed.

[0006] However, if the aforementioned methods are simply adopted, the following issues need to be addressed.

[0007] That is, when assembling the connector component 5e onto the manifold body component 70e, the flange portion 71e and the cylindrical portion 52 need to be fitted together in a way that prevents them from shifting position. Therefore, during the brazing process of applying brazing filler metal 30 to the outer side of the front end of the flange portion 71e and heating and melting the filler metal 30, the molten filler metal sometimes does not smoothly enter the tiny gap between the inner circumferential surface of the flange portion 71e and the outer circumferential surface of the cylindrical portion 52, thus hindering proper brazing. Ideally, through capillary action, a large amount of molten filler metal should pass through the tiny gap to the front end of the cylindrical portion 52 (the portion indicated by the symbol Na), and it is desirable to form a weld bead in this portion Na. Without this weld bead formation, in addition to lower brazing strength, there is a concern that some of the Na may be prone to crevice corrosion.

[0008] As a means to solve this problem, it is possible to coat the solder 30 on a portion of the Na, but there is a concern that a portion of the solder 30 coated on the Na may flow into the interior of the manifold 7e, which is not preferred.

[0009] The aforementioned defects are not limited to the brazing connection between the manifold body components and the joint components of the heat exchanger, but also occur when other components are brazed together.

[0010] [Existing technical documents]

[0011] [Patent Literature]

[0012] [Patent Document 1] Japanese Patent No. 7225682

[0013] [Patent Document 2] Japanese Patent Application Publication No. 2002-364996

[0014] [Patent Document 3] Japanese Patent No. 7274085 Summary of the Invention

[0015] [The problem the invention aims to solve]

[0016] The present invention was conceived based on the above-described situation, and its objective is to provide a brazed connection structure that can be suitably brazed through a simple structure, a heat exchanger including said structure, and a method for manufacturing said brazed connection structure.

[0017] [Technical means to solve the problem]

[0018] To address the aforementioned issues, the following technical means are employed in this invention.

[0019] The brazing connection structure provided by the first aspect of the present invention includes: a first member, a portion of which is formed as a cylindrical flange portion serving as a pressing processing portion; a second member having a cylindrical portion embedded in the flange portion and connected to the first member; and a brazing portion, wherein brazing filler metal enters between the inner peripheral surface of the flange portion and the outer peripheral surface of the cylindrical portion, and the flange portion of the brazing connection structure is formed as a polygonal cylindrical shape for incorporating the cylindrical portion, and the brazing portion is configured as a gap between the inner surface portion of each corner of the flange portion into which the brazing filler metal enters and the outer peripheral surface of the cylindrical portion.

[0020] Based on this structure, the following effects can be achieved.

[0021] That is, since the flange of the first component is formed into a polygonal cylindrical shape for the cylindrical portion of the second component to be inscribed within, these flanges and the cylindrical portion can be fitted together without wobbling before brazing. Furthermore, gaps are formed between the inner surfaces of each corner of the flange and the outer circumferential surface of the cylindrical portion, and the brazing portion is configured such that, for example, the brazing filler metal enters these gaps from the outer side of the front end of the flange, thus reaching the front side of the front end of the cylindrical portion, thereby ensuring the formation of a weld bead in that portion. Therefore, the brazing strength can be improved, and crevice corrosion at the front end of the cylindrical portion can also be appropriately suppressed.

[0022] In this invention, preferably, the flanged portion is a polygonal cylindrical shape with a hexagonal or greater shape.

[0023] With this structure, it is preferable that a gap of suitable brazing width is formed between the inner surface of each corner of the flange and the outer peripheral surface of the cylindrical part.

[0024] Furthermore, more preferably, when the diameter of the cylindrical portion is large, the flange portion is formed into a polygonal cylindrical shape with a large number of corners, compared to the case where the diameter of the cylindrical portion is small.

[0025] In this invention, preferably, the flanged portion is a regular polygonal cylindrical shape with an even number of angles.

[0026] This structure simplifies the dimensional management of the flanged portion. Specifically, if the flanged portion is a regular polygonal cylinder with an even number of angles, the width between two opposing angles separated by the center of the regular polygon, or the width between two non-angled portions separated by the center, can be measured to easily determine the flanged portion's dimensions, thus simplifying dimensional management. Unlike this structure, dimensional management is difficult when the flanged portion is a polygonal cylinder with an odd number of angles, but this difficulty is eliminated by this structure.

[0027] In this invention, it is preferable that the inner surface portion of each corner of the flange portion is formed as a concave curved surface.

[0028] According to this structure, compared with the case where the inner surface of each corner of the flange is not formed into a concave curved surface, the gap between the inner surface of each corner of the flange and the outer peripheral surface of the cylindrical part can be a smooth shape, thus becoming an area where the brazing filler metal can easily enter.

[0029] In this invention, it is preferable that the maximum width of the gap in the radial direction of the cylindrical portion is set to 0.1 mm to 0.2 mm.

[0030] As an example of the brazed connection structure involved in this invention, the inventors prepared flanged portions or cylindrical portions of various sizes (outer diameter of the cylindrical portion from 8 mm to 30 mm) to broadly address various tube bodies used in heat exchangers and the like for hot water supply devices, and conducted brazing tests. The results showed that, in order to obtain the intended effect of this invention, the specific size of the flanged portion or cylindrical portion is not particularly important; it is preferable to set the maximum width of the gap in the radial direction of the cylindrical portion within the range of 0.1 mm to 0.2 mm.

[0031] A heat exchanger provided by a second aspect of the present invention includes a manifold section connected to the ends of a plurality of heat transfer tubes and used for the inflow or outflow of hot water into or out of the plurality of heat transfer tubes. A manifold main body member constituting the manifold section includes an orifice and a cylindrical flange protruding from the inner periphery of the orifice to the outer side of the manifold main body member. A connector member or piping pipe having a cylindrical portion is connected to the flange. The heat exchanger, as a structure for connecting the connector member or the piping pipe to the flange, uses a brazing connection structure provided by a first aspect of the present invention. The manifold main body member is equivalent to the first member, and the connector member or the piping pipe is equivalent to the second member.

[0032] According to this structure, the same effect as described with respect to the brazing connection structure provided by the first aspect of the present invention can be obtained, enabling the joint member or piping pipe to be properly and securely brazed to the main manifold member constituting the manifold section of the heat exchanger.

[0033] The method for manufacturing a brazed connection structure provided by the third aspect of the present invention includes: an assembly step in which a cylindrical portion of a first member having a cylindrical flange is embedded in a cylindrical portion of a second member; and a brazing step in which, after the assembly step, brazing filler metal is provided between the inner circumferential surface of the flange and the outer circumferential surface of the cylindrical portion. As a forming step of the flange, the method for manufacturing the brazed connection structure further includes a step of forming the flange into a polygonal cylindrical shape that the cylindrical portion can intrude into by using a polygonal punch and a die.

[0034] Based on this structure, the brazing connection structure provided by the first aspect of the present invention can be suitably manufactured.

[0035] Other features and advantages of the invention become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0036] Figure 1 (a) is a schematic perspective view showing an example of a heat exchanger according to the present invention. Figure 1 (b) is Figure 1 (a) is a decomposed stereoscopic view of the main parts;

[0037] Figure 2 It means to use Figure 1 of (a) Figure 1 An explanatory diagram of an example of a hot water supply device for a heat exchanger, (b). Figure 2 The cross-sectional view shown by the solid line is equivalent to Figure 1 Section II-II of (a);

[0038] Figure 3 (a) is Figure 1 Section IIIa-IIIa of (a) Figure 3 (b) means Figure 1 (a) is a side view of an example of the heat transfer tubes of a heat exchanger. Figure 3 (c) represents Figure 1 The heat exchanger shown in (a) and Figure 3 (b) Side view of examples of different heat transfer tubes;

[0039] Figure 4 yes Figure 1 Sectional view of part IV-IV in (a) omitted;

[0040] Figure 5 (a) is Figure 3 Enlarged cross-sectional view of the main part of (a), Figure 5 (b) is Figure 5 (a) Vb-Vb profile;

[0041] Figure 6 yes Figure 5 Anatomical view of the main part of (a);

[0042] Figure 7 of (a) Figure 7 (b) means Figure 3 (a) ~ Figure 5 (b) is an explanatory diagram of a part of the manufacturing process of the main manifold component;

[0043] Figure 8 (a) means Figure 3 (a) ~ Figure 5 (b) is an explanatory diagram of another part of the manufacturing process of the main manifold component. Figure 8 (b) is Figure 8 Section (a) of VIIIb-VIIIb Figure 8 (c) is Figure 8 Section (a) of VIIIc-VIIIc;

[0044] Figure 9 It means Figure 3 (a) ~ Figure 5 (b) is an explanatory diagram of another part of the manufacturing process of the main manifold component;

[0045] Figure 10 This is a partial cross-sectional view showing another example of the present invention;

[0046] Figure 11 This is an explanatory diagram illustrating a previous technical example.

[0047] Explanation of icon numbers

[0048] HE: Heat exchanger

[0049] 3: Brazing section

[0050] 30: Brazing filler metal

[0051] 31, 32: First solder joint and second solder joint

[0052] 5: Joint component (second component)

[0053] 5A: Piping pipe (secondary component)

[0054] 52: Cylindrical section

[0055] 70: Main components of the manifold (first component)

[0056] 71: Flanged edge

[0057] 71a: Corner (flanged edge)

[0058] 90: Gap

[0059] 93a: Punch

[0060] 93b: Stamping Die Detailed Implementation

[0061] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0062] Additionally, for ease of understanding, regarding the relationship with Figure 11 Components that are the same as or similar to those in the prior art should be labeled with the same symbols.

[0063] Figure 1 (a) ~ Figure 3 The heat exchanger HE shown in (c) includes a rectangular frame-shaped housing 2 with openings on the upper and lower surfaces, a plurality of heat transfer tubes 6A, 6B disposed in the housing 2, and a pair of manifolds 7 (7A, 7B) for water inlet and hot water outlet.

[0064] The manifold section 7 has a brazed connection structure in which the manifold main body component 70 and the connector component 5 are connected by a brazing part 3. However, its details will be described later.

[0065] Except for the brazed connection structure, the basic structure of heat exchanger HE is the same as that of the heat exchanger described in Patent Document 1. Therefore, the parts that are the same as those in Patent Document 1 will be briefly described. That is, heat exchanger HE is used as... Figure 2 The hot water supply device WH shown comprises a burner 80 and another heat exchanger 81 located above the heat exchanger HE. The other heat exchanger 81 is used for sensible heat recovery, for example, using a heat transfer tube (not shown) with attached fins. Conversely, the heat exchanger HE is used for latent heat recovery. In the hot water supply device WH, the combustion gases generated by the burner 80 travel downwards, passing sequentially through the heat exchanger 81 and then the heat exchanger HE, thereby recovering sensible and latent heat from the combustion gases in sequence. This recovered heat is used to heat the hot water, which is then supplied to the desired hot water supply destination.

[0066] Multiple heat transfer tubes 6A and 6B are, for example, serpentine heat transfer tubes. Heat transfer tube 6A, for example... Figure 3 of (a) Figure 3 As shown in (b), a serpentine arrangement is formed by multiple straight tube sections 60 connected by multiple connecting tube sections 61 that appear semi-circular when viewed from the side. The multiple straight tube sections 60 extend horizontally and are arranged at intervals in the vertical direction. The heat transfer tube 6B is as follows... Figure 3 As shown in (c), the multiple straight tube sections 63 that are inclined vertically are connected in a serpentine pattern by multiple connecting tube sections 62 that appear as semicircular arcs when viewed from the side.

[0067] Multiple heat transfer tubes 6A are arranged spaced apart along their width within the shell 2. However, to increase heat recovery, the multiple heat transfer tubes 6A are arranged as follows: Figure 2 As shown, the heat transfer tubes 6A, which are arranged adjacent to each other, are staggered with varying heights. Heat transfer tubes 6B are arranged on both sides of the multiple heat transfer tubes 6A.

[0068] The two ends of these heat transfer tubes 6A and 6B in the longitudinal direction pass through the side wall portion 21 of the housing 2 and are led out to the outside of the housing 2, and are connected to the manifold portion 7 (7A, 7B).

[0069] Each manifold section 7 is configured such that a pair of manifold main body members 70a and 70 are interconnected (brazed connection) on the base side and the cover side, thereby forming a chamber 72 inside these sections that communicates with the ends of heat transfer tubes 6A and 6B (see reference). Figure 4 , Figure 5 (a) and Figure 5(b) A connector component 5 is brazed to the main pipe component 70, and the opening 53 of the connector component 5 serves as the inlet or outlet of hot water into the chamber 72.

[0070] The specific structure of the brazed connection between the main manifold component 70 and the joint component 5 is as follows.

[0071] That is, the connector component 5 is a component used to easily connect a piping component (not shown) for water inlet or hot water outlet to the manifold 7, and is a pressed metal product made of stainless steel or other metals. The connector component 5 is configured such that a cylindrical portion 52 with a smaller diameter than the cylindrical main body 51 is formed at the front of the cylindrical main body 51, which has a flange portion 50 connected to its rear. (See also...) Figure 6 ).

[0072] The main body component 70 of the manifold, like the connector component 5, is a pressed metal product made of stainless steel or the like. It includes a wall portion 73 with a curved cross section for forming the chamber 72, a hole portion 74 (flanged hole) provided on the wall portion 73, and a cylindrical flange portion 71 that is a pressed part protruding from the inner periphery of the hole portion 74 toward the outer side of the manifold 7.

[0073] Flanged part 71 Figure 5 As shown in (b), it is a regular polygonal cylindrical shape, preferably a regular polygonal cylindrical shape with a hexagon or larger, and in this embodiment, it is a regular decagonal cylindrical shape. The flanged portion 71 is embedded in a form that allows the cylindrical portion 52 of the connector member 5 to be internally connected. Therefore, a gap 90 is formed between the inner surface of each corner portion 71a of the flanged portion 71 and the outer peripheral surface of the cylindrical portion 52. Figure 5 (a) and Figure 5 (b) is omitted, but the brazing filler metal of the brazing part 3 described later enters the gap 90).

[0074] like Figure 5 As shown in a partial enlarged view of (b), the inner surface of each corner 71a of the flange 71 is formed as a concave curved surface bent with an appropriate radius of curvature Ra.

[0075] Furthermore, the maximum width Lmax of the gap 90 in the radial direction of the cylindrical portion 52 (the relative dimension between the most concave portion of the inner surface of the plurality of corner portions 71a and the outer peripheral surface of the cylindrical portion 52 in the radial direction) is set to a range of 0.1 mm to 0.2 mm (all widths of the plurality of gaps 90 formed corresponding to the plurality of corner portions 71a need not be within this range, as long as the maximum width among the dimensions of these plurality of gaps 90 is within this range).

[0076] Brazing part 3, as in Figure 5As clearly shown in (a), the flange 71 is configured with a first solder foot 31 on the outer side of its front end, and a portion of the brazing filler metal 30 enters from the first solder foot 31 into the gap (gap 90) between the inner circumferential surface of the flange 71 and the outer circumferential surface of the cylindrical portion 52. A portion of the brazing filler metal 30 reaches the front side of the front end of the cylindrical portion 52 and forms a second solder foot 32. The brazing filler metal 30 is, for example, nickel brazing filler metal.

[0077] The brazed connection structure is manufactured as follows.

[0078] That is, when manufacturing the main manifold component 70, firstly as follows: Figure 7 As shown in (a), a flat metal plate 79 is subjected to a deep drawing and pressing process using a punch 92a and a die 92b to produce a material as shown in (a). Figure 7 The intermediate part 70' of the main manifold component as shown in (b). Then, as... Figure 8 As shown in (a), the forming process of the flanged portion 71 is performed using a separate punch 93a and a die 93b. Figure 8 of (b) Figure 8 As shown in (c), the punch 93a has a portion with a decagonal cross-section, and the die 93b has an opening 930 with a decagonal shape when viewed from above. Through this process, a decagonal cylindrical flange 71 can be formed (see reference). Figure 9 Then, the main manifold component 70 can be cut off from the remaining part of the metal plate 79.

[0079] Subsequently, although the illustrations are omitted, in the assembly of the heat exchanger HE, the cylindrical portion 52 of the separately prepared connector component 5 is embedded into the flanged portion 71 of the manifold main body component 70 (assembly process). Furthermore, with solder paste applied to the forming area of ​​the first solder foot 31, the heat exchanger HE is placed in a heating furnace, where the solder paste is heated and melted (brazing process). Through this process, the brazed connection structure is obtained.

[0080] In this embodiment, the following effects can be achieved.

[0081] That is, since the flanged portion 71 of the manifold main body component 70 is a regular decagonal cylinder in which the cylindrical portion 52 of the connector component 5 is inscribed, the flanged portion 71 and the cylindrical portion 52 can be set to a state without wobbling before brazing these components. Therefore, the undesirable situation where the connector component 5 easily shifts position relative to the manifold main body component 70 can be eliminated before the brazing process is completed.

[0082] On the other hand, since gaps 90 are formed between the inner surface of each corner 71a of the flanged portion 71 and the outer peripheral surface of the cylindrical portion 52, the brazing filler metal 30 of the brazing portion 3 can be inserted into the gaps 90 and reach the front end of the cylindrical portion 52 via the gaps 90 to form a second weld leg 32. Therefore, the brazing strength can be improved, and crevice corrosion near the front end of the cylindrical portion 52 can also be appropriately suppressed.

[0083] In this embodiment, the flange 71 is a regular decagonal cylindrical shape, and the total number of corner portions 71a is even. Therefore, in Figure 5 In (b), the longitudinal width La (the width between the vertices of the two upper and lower corners 71a) and the lateral width Lb (the width between the two left and right non-corner parts) of the flange 71 can be easily measured, thus making it easy to manage the overall dimensions of the flange 71. This advantage cannot be obtained when the total number of corners 71a is odd.

[0084] Furthermore, in this embodiment, since the inner surface of each corner 71a of the flange 71 is formed as a concave curved surface, the shape of the gap 90 corresponding to the concave curved surface does not change drastically. Therefore, the solder can easily enter the entire area of ​​the gap 90.

[0085] Furthermore, the maximum width Lmax of the gap 90 in the radial direction of the cylindrical portion 52 is set to 0.1 mm to 0.2 mm as described above. Therefore, during the brazing process, it is more likely that the molten filler metal will reach the front side of the front end of the cylindrical portion 52 from the outer side of the front end of the flange portion 71 through capillary action. According to the experiments conducted by the inventors, it has been confirmed that in either the case where the maximum width Lmax of the gap 90 is less than 0.1 mm or more than 0.2 mm, the flow of the molten filler metal deteriorates, making it difficult to form the second weld leg 32. It has also been confirmed that the value of the maximum width Lmax is applicable almost regardless of the diameter of the component to be brazed, and is a generalizable value.

[0086] Figure 10 Another embodiment of the invention is shown. Figure 10 In this document, for components that are the same as or similar to those described in the embodiment, the same symbols are used as in the embodiment, and repeated descriptions are omitted.

[0087] exist Figure 10 In the embodiment shown, these components are brazed together in such a way that the cylindrical portion 52 of the piping pipe 5A is embedded in the flange portion 71 of the manifold main component 70.

[0088] As understood according to this embodiment, instead of the structure in which the joint member 5 is brazed to the flange 71, the structure in which the piping pipe 5A is brazed to the flange 71 without the joint member 5 is also provided.

[0089] This invention is not limited to the embodiments described herein. The specific structures of the brazed connection structure and various parts of the heat exchanger involved in this invention can be freely modified within the scope intended by this invention. The specific structures of each step in the manufacturing method of the brazed connection structure involved in this invention can also be freely modified.

[0090] In the described embodiment, the flange is formed into a regular decagonal cylindrical shape, but the present invention is not limited to this and may also be formed into other polygonal cylindrical shapes. However, in the present invention, it is preferable to form the flange into a polygonal cylindrical shape of hexagon or more, and as described above, it is more preferable to increase the total number of corners of the flange when the diameter is large, compared to the case where the diameter of the flange or cylindrical part is small.

[0091] The first and second components mentioned in this invention are not limited to the manifold main body component 70 of the heat exchanger HE, or the joint component 5, or the piping pipe 5A. Various components can be used as the first and second components.

Claims

1. A brazed connection structure, comprising: The first component has a portion formed as a cylindrical flange portion that serves as a pressing processing part; The second component has a cylindrical portion embedded in the flange and is connected to the first component; and The brazing section, wherein the brazing filler metal enters between the inner circumferential surface of the flanged section and the outer circumferential surface of the cylindrical section, and the brazing connection structure is characterized in that... The flanged portion is formed into a polygonal cylindrical shape for incorporation within the cylindrical portion. The brazing portion is configured such that the brazing filler metal enters the gap between the inner surface of each corner of the flange portion and the outer peripheral surface of the cylindrical portion.

2. The brazed connection structure according to claim 1, wherein, The flanged part is a polygonal cylindrical shape with a hexagonal or larger shape.

3. The brazing connection structure according to claim 2, wherein, The flanged part is a regular polygonal cylindrical shape with an even number of angles.

4. The brazed connection structure according to claim 1, wherein, The inner surface of each corner of the flanged portion is formed into a concave curved surface.

5. The brazing connection structure according to claim 1, wherein, The maximum width of the gap in the radial direction of the cylindrical portion is set to 0.1 mm to 0.2 mm.

6. A heat exchanger comprising a manifold connected to the ends of a plurality of heat transfer tubes and used for the inflow or outflow of hot water into or out of the plurality of heat transfer tubes. The main manifold component constituting the manifold section includes a bore and a cylindrical flange protruding from the inner periphery of the bore towards the outer side of the main manifold component. A connector component or piping pipe with a cylindrical portion is connected to the flange. The heat exchanger is characterized in that... As a structure for connecting the joint member or the piping pipe to the flange, a brazing connection structure as described in any one of claims 1 to 5 is used. The main manifold component is equivalent to the first component, and the connector component or the piping pipe is equivalent to the second component.

7. A method for manufacturing a brazed connection structure, comprising: In the assembly process, the flange portion of the first component, which has a cylindrical flange portion, is embedded into the cylindrical portion of the second component; and In the brazing process, after the assembly process, brazing filler metal is provided at the brazing portion between the inner circumferential surface of the flanged part and the outer circumferential surface of the cylindrical part. The manufacturing method of this brazed connection structure is characterized by... As part of the process of forming the flanged portion, there is also a process of forming the flanged portion into a polygonal cylindrical shape that can be inscribed within the cylindrical portion by using a polygonal punch and a die.

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