EP4624852A1

EP4624852A1 - Offset fin, heat exchanger, plate material for fin, and offset fin manufacturing method

Info

Publication number: EP4624852A1
Application number: EP23911282.4A
Authority: EP
Inventors: Shunsaku Eguchi; Yoichi Uefuji; Tomoto Nagai
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Ltd
Priority date: 2022-12-26
Filing date: 2023-09-08
Publication date: 2025-10-01
Also published as: EP4624852A4; WO2024142498A1; JP2024092386A

Abstract

An offset fin includes a plurality of waveform structures configured to extend in a first direction perpendicular to a plate thickness direction while periodically meandering in the plate thickness direction, each of the waveform structures including a first bonding plate portion and a second bonding plate portion that are located to deviate from each other in the plate thickness direction and are alternately arranged in the first direction and a plurality of connection plate portions each of which extends in the plate thickness direction and connects the first bonding plate portion and the second bonding plate portion adjacent to each other in the first direction and which are arranged at intervals in the first direction, in which the plurality of waveform structures are arranged in a second direction perpendicular to the plate thickness direction and the first direction, the connection plate portions in two waveform structures adjacent to each other in the second direction are located to deviate from each other in the first direction, and, in at least one of the waveform structures, a leading edge surface of the connection plate portion that faces a first side in the second direction is inclined toward a second side in the second direction with respect to the plate thickness direction.

Description

TECHNICAL FIELD

The present disclosure relates to an offset fin, a heat exchanger, a plate material for a fin, and an offset fin manufacturing method.
Priority is claimed on Japanese Patent Application No. 2022-208283, filed on December 26, 2022 , the content of which is incorporated herein by reference.

BACKGROUND ART

Patent Document 1 discloses an offset fin used in a heat exchanger. The offset fin has a plurality of waveform structures having a waveform shape that meanders periodically in an up-down direction as viewed from a flow direction of a fluid. Fin portions that extend in the up-down direction in each waveform structure are arranged at regular intervals in a width direction (a left-right direction as viewed from the flow direction of the fluid). The interval between the fin portions is the same in the plurality of waveform structures. The plurality of waveform structures are arranged in the flow direction of the fluid. Two waveform structures (a first waveform structure and a second waveform structure) that are adjacent to each other in the flow direction are disposed to be offset in the width direction such that the fin portions in the two waveform structures are located to deviate from each other in the width direction. Therefore, the fluid that passes between the fin portions in the first waveform structure located on the upstream side hits a leading edge of the fin portion in the second waveform structure located on the downstream side, which promotes the occurrence of turbulence in the fluid flowing through the offset fin. Since the development of a thermal boundary layer appearing on a surface of the offset fin due to the flow of the fluid can be suppressed by the occurrence of the turbulence, the heat transfer performance between the fluid and the offset fin is improved.
In addition, in the offset fin disclosed in Patent Document 1, the fin portion in the waveform structure extends while being inclined in the width direction with respect to the flow direction of the fluid. Therefore, the occurrence of the turbulence in the fluid flowing through the offset fin is further promoted, which improves the heat transfer performance between the fluid and the offset fin.

Citation List

Patent Document

Patent Document 1: PCT International Publication No. WO2015/170456

SUMMARY OF INVENTION

Technical Problem

In this type of offset fin, there is room for improving the heat transfer performance between the offset fin and the fluid.
The present disclosure has been made in order to solve the above-described problems, and an object of the present disclosure is to provide an offset fin that can improve heat transfer performance between the offset fin and a fluid, a heat exchanger including the offset fin, a plate material for a fin that is used for manufacturing the offset fin, and an offset fin manufacturing method using the plate material for a fin.

Solution to Problem

In order to achieve the above object, according to the present disclosure, there is provided an offset fin including a plurality of waveform structures configured to extend in a first direction perpendicular to a plate thickness direction while periodically meandering in the plate thickness direction, each of the waveform structures including a first bonding plate portion and a second bonding plate portion that are located to deviate from each other in the plate thickness direction and are alternately arranged in the first direction and a plurality of connection plate portions each of which extends in the plate thickness direction and connects the first bonding plate portion and the second bonding plate portion adjacent to each other in the first direction and which are arranged at intervals in the first direction. The plurality of waveform structures are arranged in a second direction perpendicular to the plate thickness direction and the first direction. The connection plate portions in two waveform structures adjacent to each other in the second direction are located to deviate from each other in the first direction. In at least one of the waveform structures, a leading edge surface of the connection plate portion that faces a first side in the second direction is inclined toward a second side in the second direction with respect to the plate thickness direction.
In addition, according to the present disclosure, there is provided a heat exchanger including the offset fin and a pair of plates configured to be disposed with the offset fin interposed therebetween in the plate thickness direction. The first bonding plate portion is overlapped and bonded to a first plate of the pair of plates. The second bonding plate portion is overlapped and bonded to a second plate of the pair of plates.
Further, according to the present disclosure, there is provided a plate material for a fin having a single plane, the plate material for a fin including a plurality of unit structures each of which includes a first bonding plate portion and a second bonding plate portion that are alternately arranged at intervals in a first direction along the plane and a plurality of connection plate portions each of which is disposed between the first bonding plate portion and the second bonding plate portion in the first direction and connects the first bonding plate portion and the second bonding plate portion. The plurality of unit structures are arranged in a second direction perpendicular to the first direction along the plane. Two unit structures that are adjacent to each other in the second direction are located to deviate from each other in the first direction. In at least one of the unit structures, a leading edge surface of the connection plate portion that faces a first side in the second direction is inclined toward a second side in the second direction with respect to the first direction. In the same unit structure, a first boundary line between the first bonding plate portion and the connection plate portion and a second boundary line between the second bonding plate portion and the connection plate portion extend without being inclined with respect to the second direction.
Furthermore, according to the present disclosure, there is provided an offset fin manufacturing method for manufacturing an offset fin using the plate material for a fin, the offset fin manufacturing method including folding the plate material for a fin in a valley fold at the first boundary line and folding the plate material for a fin in a mountain fold at the second boundary line.

Advantageous Effects of Invention

According to the present disclosure, it is possible to improve the heat transfer performance between the offset fin and the fluid.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] A perspective view schematically showing a heat exchanger according to an embodiment of the present disclosure.
[FIG. 2] A plan view showing an offset fin according to an embodiment of the present disclosure.
[FIG. 3] A front view showing the offset fin shown in FIG. 2 as viewed from a III direction of FIG. 2.
[FIG. 4] A side view showing the offset fin shown in FIG. 2 as viewed from a IV direction of FIG. 2.
[FIG. 5] A front view showing a main portion of the offset fin shown in FIGS. 2 to 4 as viewed from a Y-axis direction.
[FIG. 6] A side view showing the main portion of the offset fin shown in FIGS. 2 to 4 as viewed from an X-axis direction.
[FIG. 7] A plan view showing the main portion of the offset fin shown in FIGS. 2 to 4 as viewed from a Z-axis direction.
[FIG. 8] A plan view showing a plate material for a fin according to an embodiment of the present disclosure.

DESCRIPTION OF EMBODIMENTS

[HEAT EXCHANGER]

Hereinafter, an embodiment of the present disclosure will be described below with reference to FIGS. 1 to 8.
As shown in FIG. 1, a heat exchanger 1 is a so-called plate-type heat exchanger and has a structure in which an offset fin 3 is disposed between a pair of plates 2.
The heat exchanger 1 shown in FIG. 1 includes a plurality of plates 2 and a plurality of offset fins 3. The plurality of plates 2 are arranged at intervals in a thickness direction thereof (Z-axis direction). The offset fin 3 is disposed between a pair of plates 2 adjacent to each other in the thickness direction and is bonded to each plate 2 by brazing or the like. The offset fin 3 functions as a strength member that secures a gap between the pair of plates 2. In addition, the offset fin 3 forms a flow passage through which a fluid flows in one direction (Y-axis direction) between the pair of plates 2. The fluid may be a liquid or a gas and is not particularly limited.
Therefore, the heat exchanger 1 has a plurality of flow passages arranged in the thickness direction. The plurality of flow passages include a high-temperature-side flow passage through which a high-temperature-side fluid flows and a low-temperature-side flow passage through which a low-temperature-side fluid flows. The high-temperature-side flow passage and the low-temperature-side flow passage are alternately arranged in the thickness direction. In addition, a flow direction of the high-temperature-side fluid in the high-temperature-side flow passage and a flow direction of the low-temperature-side fluid in the low-temperature-side flow passage are opposite to each other.
In the heat exchanger 1, the high-temperature-side fluid and the low-temperature-side fluid are circulated to exchange heat with each other through the plates 2 and the offset fins 3.

[Offset Fin]

Next, the offset fin 3 will be described with reference to FIGS. 2 to 7. As shown in FIGS. 2 to 4, the offset fin 3 has a plurality of waveform structures 10. The number of waveform structures 10 may be any number, but is four in the present embodiment.

[Configuration of Waveform Structure]

Each waveform structure 10 includes a first bonding plate portion 11, a second bonding plate portion 12, and a plurality of connection plate portions 13.
In each waveform structure 10, the first bonding plate portion 11 and the second bonding plate portion 12 are located to deviate from each other in a plate thickness direction (Z-axis direction) thereof. In addition, the first bonding plate portion 11 and the second bonding plate portion 12 are alternately arranged in the X-axis direction (first direction) perpendicular to the Z-axis direction.
In the waveform structure 10 shown in FIGS. 2 and 3, the dimensions (width dimensions) of the first bonding plate portion 11 and the second bonding plate portion 12 in the X-axis direction are equal to each other. The width dimensions of the first and second bonding plate portions 11 and 12 in the plurality of waveform structures 10 are equal to each other. In addition, the first bonding plate portion 11 is located on a negative Z-axis direction side (a first side in the plate thickness direction), and the second bonding plate portion 12 is located on a positive Z-axis direction side (a second side in the plate thickness direction). In each waveform structure 10 shown in FIGS. 2 and 3, the number of first bonding plate portions 11 is two, and the number of second bonding plate portions 12 is two. However, the present disclosure is not limited thereto.
Each of the plurality of connection plate portions 13 in each waveform structure 10 extends in the Z-axis direction and connects the first bonding plate portion 11 and the second bonding plate portion 12 adjacent to each other in the X-axis direction. The plurality of connection plate portions 13 are arranged at intervals in the X-axis direction. In addition, each connection plate portion 13 extends in the Y-axis direction without being inclined in the X-axis direction with respect to the Y-axis direction. The dimensions (height dimensions) of the connection plate portions 13 in the Z-axis direction in the plurality of waveform structures 10 are equal to each other.
As shown in FIG. 3, each waveform structure 10 extends in the X-axis direction while periodically meandering in the Z-axis direction. Specifically, each waveform structure 10 is formed in a waveform shape in which the connection plate portion 13, the first bonding plate portion 11, the connection plate portion 13, and the second bonding plate portion 12 arranged in order in the X-axis direction form one period as viewed from the Y-axis direction (second direction) perpendicular to the Z-axis direction and the X-axis direction as shown in FIG. 3.
As shown in FIG. 3, in each waveform structure 10 according to the present embodiment, a connection portion between the first bonding plate portion 11 and the connection plate portion 13 is rounded such that the first bonding plate portion 11 and the connection plate portion 13 are smoothly connected to each other. In addition, a connection portion between the second bonding plate portion 12 and the connection plate portion 13 is rounded such that the second bonding plate portion 12 and the connection plate portion 13 are smoothly connected to each other. Each connection portion is formed in a fan shape as viewed from the Y-axis direction as shown in FIG. 3. The radius of curvature of the fan-shaped connection portion may be larger than, for example, the thickness dimensions of the first and second bonding plate portions 11 and 12 and the connection plate portion 13.

[Relative Disposition of Plurality of Waveform Structures]

The plurality of waveform structures 10 are arranged in the Y-axis direction (second direction) perpendicular to the Z-axis direction and the X-axis direction. The connection plate portions 13 in two waveform structures 10 that are adjacent to each other in the Y-axis direction are located to deviate from each other in the X-axis direction. Specifically, the two waveform structures 10 adjacent to each other in the Y-axis direction deviate from each other in the X-axis direction by 1/4 of the period. Therefore, as viewed from the Y-axis direction, between two connection plate portions 13 adjacent to each other in the X-axis direction in a predetermined waveform structure 10, the connection plate portion 13 in another waveform structure 10 that is located adjacent to the predetermined waveform structure 10 in the Y-axis direction is located.
In the following description, four waveform structures 10 that are arranged in order in the positive Y-axis direction (on a second side in the second direction) may be referred to as a first waveform structure 10A, a second waveform structure 10B, a third waveform structure 10C, and a fourth waveform structure 10D.
As shown in FIGS. 2 and 3, the first waveform structure 10A, the second waveform structure 10B, and the third waveform structure 10C that are continuously arranged in order in the positive Y-axis direction deviate from each other by 1/4 of the period in the negative X-axis direction (toward a first side in the first direction). The fourth waveform structure 10D deviates from the third waveform structure 10C in the positive X-axis direction (toward a second side in the first direction) by 1/4 period. Therefore, the second waveform structure 10B and the fourth waveform structure 10D are located without deviating from each other in the X-axis direction, that is, overlap each other in the Y-axis direction.
In the offset fin 3 in which the plurality of waveform structures 10 are disposed to be offset in the X-axis direction as described above, as shown in FIG. 3, a plurality of first bonding plate portions 11 are arranged in the X-axis direction without gaps as viewed from the Y-axis direction. Specifically, the first bonding plate portions 11 in different waveform structures 10 are arranged in the X-axis direction. Similarly, a plurality of second bonding plate portions 12 are arranged in the X-axis direction without gaps. Specifically, the second bonding plate portions 12 in different waveform structures 10 are arranged in the X-axis direction.

[Leading Edge Surface of Connection Plate Portion]

As shown in FIGS. 2 and 4, in each of the connection plate portions 13 in the first and third waveform structures 10A and 10C, a leading edge surface 15 that faces the negative Y-axis direction (a first side in the second direction) is inclined in the positive Y-axis direction (toward a second side in the second direction) with respect to the Z-axis direction. In addition, in each of the first and third waveform structures 10A and 10C, the leading edge surfaces 15 of the connection plate portions 13 adjacent to each other in the X-axis direction are inclined in opposite directions along the Z-axis direction.
In the first waveform structure 10A shown in FIGS. 2 and 4, the leading edge surface 15 of the connection plate portion 13 that is located farthest in the positive X-axis direction is inclined in the positive Y-axis direction as it extends in the positive Z-axis direction. On the other hand, in the first waveform structure 10A, the leading edge surface 15 of another connection plate portion 13 that is adjacent to the above-described connection plate portion 13 in the negative X-axis direction is inclined in the negative Y-axis direction as it extends in the positive Z-axis direction.

[Leading Edge Surface of Bonding Plate Portion]

As shown in FIG. 2, each of the first and second bonding plate portions 11 and 12 in each waveform structure 10 has a leading edge surface 17 that faces the negative Y-axis direction (a first side in the second direction). The leading edge surface 17 of each of the bonding plate portions 11 and 12 includes two inclined surfaces 171 and 172 (a first inclined surface 171 and a second inclined surface 172) that are arranged in order in the positive X-axis direction. Both of the two inclined surfaces 171 and 172 are inclined in the Y-axis direction with respect to the X-axis direction. However, the two inclined surfaces 171 and 172 are inclined in opposite directions. Therefore, the leading edge surface 17 of each of the bonding plate portions 11 and 12 is formed in a V-shape in a plan view.
Specifically, in each of the bonding plate portions 11 and 12 in the first and third waveform structures 10A and 10C, the first inclined surface 171 is inclined in the positive Y-axis direction as it extends in the positive X-axis direction from an end part of each of the bonding plate portions 11 and 12 in the negative X-axis direction. On the other hand, the second inclined surface 172 is inclined in the positive Y-axis direction as it extends in the negative X-axis direction from an end part of each of the bonding plate portions 11 and 12 in the positive X-axis direction. Therefore, the leading edge surface 17 of each of the bonding plate portions 11 and 12 in the first and third waveform structures 10A and 10C is formed in a V-shape that is recessed in the positive Y-axis direction in a plan view.
Meanwhile, in each of the bonding plate portions 11 and 12 in the second and fourth waveform structures 10B and 10D, the first inclined surface 171 is inclined in the negative Y-axis direction as it extends in the positive X-axis direction from an end part of each of the bonding plate portions 11 and 12 in the negative X-axis direction. On the other hand, the second inclined surface 172 is inclined in the negative Y-axis direction as it extends in the negative X-axis direction from an end part of each of the bonding plate portions 11 and 12 in the positive X-axis direction. Therefore, the leading edge surface 17 of each of the bonding plate portions 11 and 12 in the second and fourth waveform structures 10B and 10D is formed in a V-shape that projects in the negative Y-axis direction in a plan view.
In addition, in the present embodiment, the leading edge surface 17 of each of the bonding plate portions 11 and 12 in the first and third waveform structures 10A and 10C is formed in a V-shape that is asymmetrical in the X-axis direction. Specifically, in each of the bonding plate portions 11 and 12 in the first waveform structure 10A, the first inclined surface 171 is longer than the second inclined surface 172 in a plan view. On the other hand, in each of the bonding plate portions 11 and 12 in the third waveform structure 10C, the first inclined surface 171 is shorter than the second inclined surface 172 in a plan view.
On the other hand, the leading edge surface 17 of each of the bonding plate portions 11 and 12 in the second and fourth waveform structures 10B and 10D is formed in a V-shape that is symmetrical in the X-axis direction. That is, in the second and fourth waveform structures 10B and 10D, the lengths of the first and second inclined surfaces 171 and 172 of each of the bonding plate portions 11 and 12 are equal to each other in a plan view.

[Trailing Edge Surface of Bonding Plate Portion]

As shown in FIG. 2, each of the first and second bonding plate portions 11 and 12 in each waveform structure 10 has a trailing edge surface 18 that faces the positive Y-axis direction. The trailing edge surface 18 of each of the bonding plate portions 11 and 12 is formed in a V-shape corresponding to the leading edge surface 17 in a plan view. Specifically, the trailing edge surface 18 of each of the bonding plate portions 11 and 12 in the first and third waveform structures 10A and 10C is formed in a V-shape that is symmetrical in the X-axis direction. On the other hand, the trailing edge surface 18 of each of the bonding plate portions 11 and 12 in the second and fourth waveform structures 10B and 10D is formed in a V-shape that is asymmetric in the X-axis direction.
From the above, both the bonding plate portions 11 and 12 in each waveform structure 10 are formed in a V-shape that is asymmetrical in the X-axis direction in a plan view.
In the same waveform structure 10, the first and second bonding plate portions 11 and 12 have the same shape and size in a plan view. In addition, the first and second bonding plate portions 11 and 12 have different shapes in the plurality of waveform structures 10 (first to fourth waveform structures 10A to 10D).
In the offset fin 3 according to the present embodiment, the first bonding plate portions 11 of the plurality of waveform structures 10 that are arranged adjacent to each other in the Y-axis direction are integrally formed to form a single flat plate. Specifically, a part of the trailing edge surface 18 of the first bonding plate portion 11 in the first waveform structure 10A is connected to the second inclined surface 172 of the leading edge surface 17 of the first bonding plate portion 11 in the second waveform structure 10B such that the first bonding plate portions 11 in the first and second waveform structures 10A and 10B arranged in the Y-axis direction are integrally formed. In addition, a part of the trailing edge surface 18 of the first bonding plate portion 11 in the second waveform structure 10B is connected to the second inclined surface 172 of the leading edge surface 17 of the first bonding plate portion 11 in the third waveform structure 10C such that the first bonding plate portions 11 in the second and third waveform structures 10B and 10C arranged in the Y-axis direction are integrally formed. Further, a part of the trailing edge surface 18 of the first bonding plate portion 11 in the third waveform structure 10C is connected to the first inclined surface 171 of the leading edge surface 17 of the first bonding plate portion 11 in the fourth waveform structure 10D such that the first bonding plate portions 11 in the third and fourth waveform structures 10C and 10D arranged in the Y-axis direction are integrally formed.
Similarly, the second bonding plate portions 12 in the plurality of waveform structures 10 that are arranged adjacent to each other in the Y-axis direction are integrally formed to form one flat plate. The connection aspect of the second bonding plate portions 12 in the first to fourth waveform structures 10A to 10D arranged in the Y-axis direction is the same as that of the first bonding plate portions 11.
As shown in FIGS. 1 and 3, the offset fin 3 having the above-described configuration according to the present embodiment is disposed between a pair of plates 2. Then, the first bonding plate portion 11 in each waveform structure 10 overlaps a first plate 2A of the pair of plates 2 and is bonded thereto by brazing or the like. In addition, the second bonding plate portion 12 in each waveform structure 10 overlaps a second plate 2B of the pair of plates 2 and is bonded thereto by brazing or the like.

[Flow by Leading Edge Surface of Connection Plate Portion]

Next, a flow of a fluid in the heat exchanger 1 including the offset fin 3 according to the present embodiment will be described.
As shown in FIGS. 5 and 6, in the offset fin 3 according to the present embodiment, the leading edge surface 15 of each connection plate portion 13 in the first waveform structure 10A is inclined in the positive Y-axis direction with respect to the Z-axis direction. Therefore, when the fluid flows through the offset fin 3 in the positive Y-axis direction, the fluid flows along the inclined leading edge surface 15 of the connection plate portion 13 as represented by arrows D1 and D2 in FIGS. 5 and 6. That is, the fluid flows along the inclined leading edge surface 15 of the connection plate portion 13 not only in the positive Y-axis direction but also in the Z-axis direction. Therefore, swirling flows (secondary flows) represented by arrows D3 and D4 in FIG. 5 occur in a region that is adjacent to the connection plate portion 13 in the X-axis direction. The swirling flow is a spiral flow having the Y-axis direction as an axis.
In addition, in the first waveform structure 10A, the leading edge surfaces 15 of two connection plate portions 13 that are adjacent to each other in the X-axis direction are inclined in opposite directions along the Z-axis direction. Therefore, in the leading edge surfaces 15 of the two adjacent connection plate portions 13, the fluid flows in opposite directions along the Z-axis direction as represented by the arrows D1 and D2 in FIGS. 5 and 6. Therefore, a complex swirling flow can occur between the two adjacent connection plate portions 13 as represented by the arrows D3 and D4 in FIG. 5.
The same swirling flow as described above also occurs in the third waveform structure 10C having the same structure as the first waveform structure 10A (the structure in which the leading edge surface 15 of the connection plate portion 13 is inclined in the positive Y-axis direction with respect to the Z-axis direction and the structure in which the leading edge surfaces 15 of two connection plate portions 13 adjacent to each other in the X-axis direction are inclined in opposite directions along the Z-axis direction), which is not shown.

[Flow by Leading Edge Surface of Bonding Plate Portion]

In addition, as shown in FIGS. 5 and 7, in the offset fin 3 according to the present embodiment, the leading edge surface 17 of the second bonding plate portion 12 in the first waveform structure 10A has the first and second inclined surfaces 171 and 172 that are inclined in the positive Y-axis direction with respect to the X-axis direction. Therefore, when the fluid flows through the offset fin 3 in the positive Y-axis direction, the fluid flows along the first and second inclined surfaces 171 and 172 as represented by arrows D5 and D6 in FIGS. 5 and 7. That is, the fluid flows along the first and second inclined surfaces 171 and 172 not only in the positive Y-axis direction but also in the X-axis direction. Therefore, swirling flows represented by arrows D7 and D8 in FIG. 5 occur in a region that is adjacent to the second bonding plate portion 12 in the Z-axis direction.
In addition, in the second bonding plate portion 12 in the first waveform structure 10A, the first and second inclined surfaces 171 and 172 are inclined in opposite directions such that the leading edge surface 15 is formed in a V-shape that is recessed in the positive Y-axis direction in a plan view. Therefore, the swirling flows D7 and D8 having opposite rotation directions occur in a region that is adjacent to the second bonding plate portion 12 in the Z-axis direction.
The same swirling flow as described above also occurs in the first bonding plate portion 11 (see FIG. 2) in the first waveform structure 10A having the first and second inclined surfaces 171 and 172, which is not shown. In addition, the same swirling flow as described above also occurs in the first inclined surface 171 of each of the bonding plate portions 11 and 12 in the second and third waveform structures 10B and 10C and in the second inclined surface 172 of each of the bonding plate portions 11 and 12 in the fourth waveform structure 10D (see FIG. 2).

[Flow by Arrangement of Bonding Plate Portions]

In addition, as shown in FIG. 3, in the offset fin 3 according to the present embodiment, the first bonding plate portions 11 in different waveform structures 10 are arranged in the X-axis direction without gaps as viewed from the Y-axis direction. Therefore, a level difference caused by the first bonding plate portion 11 appears in the Y-axis direction at any position in the X-axis direction. Similarly, since the second bonding plate portions 12 in different waveform structures 10 are arranged in the X-axis direction without gaps as viewed from the Y-axis direction, a level difference caused by the second bonding plate portions 12 appears in the Y-axis direction at any position in the X-axis direction. Therefore, when the fluid flows through the offset fin 3 in the positive Y-axis direction, turbulence caused by the level difference occurs at any position in the X-axis direction.

[Plate Material for Fin]

Next, a plate material 100 for a fin that is used for manufacturing the offset fin 3 will be described with reference to FIG. 8.
The plate material 100 for a fin shown in FIG. 8 has a single plane, that is, the plate material 100 for a fin is formed in a flat plate shape. The plate material 100 for a fin is a plate material that can be folded. The plate material 100 for a fin has a plurality of unit structures 110. The unit structure 110 corresponds to the waveform structure 10 in the manufactured offset fin 3. Therefore, the number of unit structures 110 in the present embodiment is four. The four unit structures 110 are arranged in the Y-axis direction (second direction) along the plane of the plate material 100 for a fin. In the following description, the four unit structures 110 arranged in order in the positive Y-axis direction (on a second side in the second direction) may be referred to as a first unit structure 110A, a second unit structure 110B, a third unit structure 110C, and a fourth unit structure 110D. The first to fourth unit structures 110A to 110D correspond to the first to fourth waveform structures 10A to 10D in the offset fin 3, respectively.

[Configuration of Unit Structure]

Each unit structure 110 includes a first bonding plate portion 11, a second bonding plate portion 12, and a plurality of connection plate portions 13 that correspond to the offset fin 3.
The first bonding plate portion 11 and the second bonding plate portion 12 are alternately arranged at intervals in the X-axis direction (first direction) perpendicular to the Y-axis direction along the plane of the plate material 100 for a fin. The first bonding plate portion 11 and the second bonding plate portion 12 in each unit structure 110 have the same shape and size as those in each waveform structure 10 of the offset fin 3. That is, each of the bonding plate portions 11 and 12 has the leading edge surface 17 and the trailing edge surface 18. In addition, the leading edge surface 17 of each of the bonding plate portions 11 and 12 has the first inclined surface 171 and the second inclined surface 172. In each unit structure 110 shown in FIG. 8, the number of first bonding plate portions 11 is two, and the number of second bonding plate portions 12 is two. However, the present disclosure is not limited thereto.
In each unit structure 110, each of the plurality of connection plate portions 13 is disposed between the first bonding plate portion 11 and the second bonding plate portion 12 in the X-axis direction and connects the first bonding plate portion 11 and the second bonding plate portion 12. The plurality of connection plate portions 13 are arranged at intervals in the X-axis direction.
In the first and third unit structures 110A and 110C, the leading edge surface 15 of the connection plate portion 13 that faces the negative Y-axis direction (a first side in the second direction) is inclined in the positive Y-axis direction with respect to the X-axis direction. The inclination directions of the leading edge surfaces 15 of the plurality of connection plate portions 13 in the same unit structure 110 are the same. In addition, the inclination directions of the leading edge surfaces 15 of the connection plate portions 13 in the first unit structure 110A and the third unit structure 110C are opposite to each other. Further, in the second and fourth unit structures 110B and 110D, the leading edge surface of the connection plate portion 13 extends in the X-axis direction without being inclined with respect to the X-axis direction.
In the same unit structure 110, the plurality of connection plate portions 13 have the same shape and size as viewed from the Z-axis direction (the plate thickness direction of the plate material 100 for a fin). In addition, the shapes of the connection plate portions 13 in the plurality of unit structures 110 are different from each other.
In each unit structure 110, a first boundary line 141 between the first bonding plate portion 11 and the connection plate portion 13 and a second boundary line 142 between the second bonding plate portion 12 and the connection plate portion 13 extend without being inclined with respect to the Y-axis direction. In FIG. 8, the first boundary line 141 is represented by a one-dot chain line. In addition, the second boundary line 142 is represented by a broken line.

[Relative Disposition of Plurality of Unit Structures]

Two unit structures 110 that are adjacent to each other in the Y-axis direction are located to deviate from each other in the X-axis direction. Specifically, the first bonding plate portions 11 in the two unit structures 110 adjacent to each other in the Y-axis direction are located to deviate from each other by about half of the width dimension of the first bonding plate portion 11 in the X-axis direction. Similarly, the second bonding plate portions 12 in two unit structures 110 adjacent to each other in the Y-axis direction are located to deviate from each other by about half of the width dimension of the second bonding plate portion 12 in the X-axis direction.
The second unit structure 110B is located to deviate from the first unit structure 110A in the negative X-axis direction. The third unit structure 110C is located to deviate from the second unit structure 110B in the negative X-axis direction. That is, three (plurality of) unit structures 110 are located to deviate from each other in the same direction. The fourth unit structure 110D is located to deviate from the third unit structure 110C in the positive X-axis direction. Therefore, the fourth unit structure 110D is located without deviating from the second unit structure 110B in the X-axis direction.
In addition, in the plate material 100 for a fin, the first bonding plate portions 11 in the plurality of unit structures 110 that are arranged adjacent to each other in the Y-axis direction are integrally formed. That is, the first bonding plate portions 11 adjacent to each other in the Y-axis direction are integrally connected to each other. Similarly, the second bonding plate portions 12 in a plurality of unit structures 110 that are arranged adjacent to each other in the Y-axis direction are integrally formed. That is, the second bonding plate portions 12 adjacent to each other in the Y-axis direction are integrally connected to each other. A specific connection aspect of the first bonding plate portions 11 adjacent to each other in the Y-axis direction and a specific connection aspect of the second bonding plate portions 12 adjacent to each other in the Y-axis direction are the same as those in the offset fin 3.
A hole 145 and a slit 146 are formed in the plate material 100 for a fin. The hole 145 and the slit 146 are formed such that the offset fin 3 according to the present embodiment can be manufactured only by folding the plate material 100 for a fin. The hole 145 and the slit 146 penetrate the plate material 100 for a fin in the plate thickness direction (Z-axis direction) thereof.
A plurality of (three in FIG. 8) holes 145 are arranged at intervals in the X-axis direction between the first unit structure 110A and the second unit structure 110B and between the third unit structure 110C and the fourth unit structure 110D. In a plan view of FIG. 8 as viewed from the Z-axis direction, the contour of each hole 145 includes an inclined side that forms a part of the leading edge surface 17 or the trailing edge surface 18 of each of the first and second bonding plate portions 11 and 12.
The slit 146 is formed between the second unit structure 110B and the third unit structure 110C, and a plurality of (three in the shown example) slits 146 are arranged at intervals in the X-axis direction. Each slit 146 extends to be inclined in the Y-axis direction with respect to the X-axis direction. The inclined slit 146 corresponds to the inclined leading edge surface 15 of the connection plate portion 13 in the third unit structure 110C and the inclined leading edge surfaces 17 (first inclined surfaces 171) of the first and second bonding plate portions 11 and 12 in the third unit structure 110C.

[Offset Fin Manufacturing Method]

Next, an example of a method for manufacturing the offset fin 3 according to the present embodiment using the plate material 100 for a fin will be described.
In order to manufacture the offset fin 3, the plate material 100 for a fin may be folded at the first and second boundary lines 141 and 142. Specifically, as shown in FIG. 8, as viewed from the positive Z-axis direction, the plate material 100 for a fin is folded in a valley fold at the first boundary line 141. In addition, the plate material 100 for a fin is folded in a mountain fold at the second boundary line 142. Therefore, it is possible to manufacture the offset fin 3 shown in FIGS. 2 to 4. The plate material 100 for a fin may be folded by, for example, press working.

[Operations and Effects]

As described above, in the offset fin 3 and the heat exchanger 1 including the offset fin 3 according to the present embodiment, the leading edge surface 15 of each of the connection plate portions 13 in the first and third waveform structures 10A and 10C is inclined in the positive Y-axis direction with respect to the Z-axis direction. Therefore, when the fluid flows through the offset fin 3 in the positive Y-axis direction, the swirling flows D3 and D4 (see FIG. 5) occur. This makes it possible to suppress the development of a thermal boundary layer appearing on a surface along the flow direction of the fluid such as a main surface of the connection plate portion 13. That is, the thickness of the thermal boundary layer can be suppressed to be small. As a result, it is possible to improve the heat transfer performance between the fluid and the offset fin 3.
In addition, in the offset fin 3 and the heat exchanger 1 according to the present embodiment, the leading edge surfaces 15 of two connection plate portions 13 adjacent to each other in the X-axis direction are inclined in opposite directions along the Z-axis direction. Therefore, the complex swirling flows D3 and D4 can occur between the two connection plate portions 13. As a result, it is possible to improve the heat transfer performance between the fluid and the offset fin 3.
In addition, in the offset fin 3 and the heat exchanger 1 according to the present embodiment, the first bonding plate portions 11 in different waveform structures 10 are arranged without gaps in the X-axis direction as viewed from the Y-axis direction. Further, the second bonding plate portions 12 in different waveform structures 10 are arranged without gaps in the X-axis direction as viewed from the Y-axis direction (see FIG. 3). Therefore, the level difference caused by the first bonding plate portion 11 and the second bonding plate portion 12 in the Y-axis direction appears at any position in the X-axis direction. Therefore, when the fluid flows through the offset fin 3 in the positive Y-axis direction, turbulence caused by the level difference occurs at any position in the first direction. As a result, the development of the thermal boundary layer is suppressed at any position in the first direction. Therefore, it is possible to improve the heat transfer performance between the fluid and the offset fin 3 over the entire offset fin 3.
In addition, in the offset fin 3 and the heat exchanger 1 according to the present embodiment, the plurality of waveform structures 10 that are continuously arranged in the Y-axis direction deviate from each other in the negative X-axis direction by 1/4 of the period. Therefore, as viewed from the Y-axis direction, the plurality of first bonding plate portions 11 can be arranged in the X-axis direction without gaps, and the plurality of second bonding plate portions 12 can be arranged in the X-axis direction without gaps.
Further, in the offset fin 3 and the heat exchanger 1 according to the present embodiment, the leading edge surface 15 of the connection plate portion 13 in each waveform structure 10 has the inclined surfaces 171 and 172 that are inclined in the Y-axis direction with respect to the X-axis direction. Therefore, when the fluid flows through the offset fin 3 in the positive Y-axis direction, the swirling flows D7 and D8 (see FIG. 5) occur due to the inclined surfaces 171 and 172. This makes it possible to suppress the development of the thermal boundary layer appearing on the surface along the flow direction of the fluid such as the main surfaces of the bonding plate portions 11 and 12. That is, the thickness of the thermal boundary layer can be suppressed to be small. As a result, it is possible to improve the heat transfer performance between the fluid and the offset fin 3.
Furthermore, in the offset fin 3 and the heat exchanger 1 according to the present embodiment, the connection portions between the bonding plate portions 11 and 12 and the connection plate portion 13 are rounded. Therefore, it is possible to suppress the accumulation of the fluid in the vicinity of the connection portion. In addition, it is possible to suppress the obstruction of the swirling flows D3, D4, D7, and D8 caused by the leading edge surface 15 of the connection plate portion 13 or the leading edge surfaces 17 of the bonding plate portions 11 and 12 by the connection portion. As a result, it is possible to suppress or prevent the deterioration of the heat transfer performance between the fluid and the offset fin 3 in the vicinity of the connection portion.
In addition, in the offset fin 3 and the heat exchanger 1 including the offset fin 3 according to the present embodiment, the connection plate portion 13 in each waveform structure 10 extends in the Y-axis direction without being inclined in the X-axis direction with respect to the Y-axis direction. Therefore, when the fluid flows through the offset fin 3 in the positive Y-axis direction, it is possible to effectively suppress a change in the flow direction of the fluid due to the connection plate portion 13. As a result, the pressure loss of the fluid can be suppressed to be small.
Further, in the plate material 100 for a fin according to the present embodiment, in the same unit structure 110, each of the first boundary line 141 between the first bonding plate portion 11 and the connection plate portion 13 and the second boundary line 142 between the second bonding plate portion 12 and the connection plate portion 13 extends without being inclined with respect to the Y-axis direction. That is, the first and second boundary lines 141 and 142 are not inclined with respect to the Y-axis direction. Therefore, in the method for manufacturing the offset fin 3 according to the present embodiment, it is possible to fold the plate material 100 for a fin at the first and second boundary lines 141 and 142 without changing the orientation (angle) of the plate material 100 for a fin. As a result, it is possible to suppress or prevent the occurrence of manufacturing errors based on the change in the orientation of the plate material 100 for a fin.
In addition, the plate material 100 for a fin according to the present embodiment has the hole 145 and the slit 146 formed therein. Therefore, when the plate material 100 for a fin is folded at the first and second boundary lines 141 and 142 in a predetermined unit structure 110, it is possible to suppress or prevent the influence of the folding on another adjacent unit structure 110.
The embodiments of the present disclosure have been described in detail above with reference to the drawings. However, the specific configuration is not limited to these embodiments, and the present disclosure includes design changes and the like without departing from the gist of the present disclosure.
In the present disclosure, a specific method that disposes the plurality of waveform structures 10 to deviate from each other in the X-axis direction such that the plurality of first bonding plate portions 11 are arranged in the X-axis direction without gaps or the plurality of second bonding plate portions 12 are arranged in the X-axis direction without gaps as viewed from the Y-axis direction is not limited to the method described in the above-described embodiment.
The present disclosure is not limited to the configuration in which the leading edge surfaces 17 of the first and second bonding plate portions 11 and 12 in each waveform structure 10 are formed in a V-shape in a plan view, and the leading edge surfaces 17 may have at least one inclined surface that is inclined in the positive Y-axis direction with respect to the X-axis direction. In addition, the inclined surface is not limited to the surface that extends linearly, and may extend, for example, in a curved manner.

The offset fin 3, the heat exchanger 1, the plate material 100 for a fin, and the method for manufacturing the offset fin 3 which are described in the above-described embodiment are understood, for example, as follows.

(1) According to a first aspect, there is provided the offset fin 3 including a plurality of waveform structures 10 configured to extend in a first direction perpendicular to a plate thickness direction while periodically meandering in the plate thickness direction, each of the waveform structures 10 including the first bonding plate portion 11 and the second bonding plate portion 12 that are located to deviate from each other in the plate thickness direction and are alternately arranged in the first direction and a plurality of connection plate portions 13 each of which extends in the plate thickness direction and connects the first bonding plate portion 11 and the second bonding plate portion 12 adjacent to each other in the first direction and which are arranged at intervals in the first direction, in which the plurality of waveform structures 10 are arranged in a second direction perpendicular to the plate thickness direction and the first direction, the connection plate portions 13 in two waveform structures 10 adjacent to each other in the second direction are located to deviate from each other in the first direction, and, in at least one of the waveform structures 10A and 10C, the leading edge surface 15 of the connection plate portion 13 that faces a first side in the second direction is inclined toward a second side in the second direction with respect to the plate thickness direction.
In the offset fin 3 having the above-described configuration, the leading edge surface 15 of the connection plate portion 13 that faces a first side in the second direction is inclined. Therefore, when the fluid flows to a second side in the second direction through the offset fin 3, the swirling flow (secondary flow) occurs due to the flow of the fluid along the leading edge surface 15 of the connection plate portion 13. This makes it possible to suppress the development of a thermal boundary layer appearing on a surface along the flow direction of the fluid such as a main surface of the connection plate portion 13. That is, the thickness of the thermal boundary layer can be suppressed to be small. As a result, it is possible to improve the heat transfer performance between the fluid and the offset fin 3.
(2) According to a second aspect, in the offset fin 3 according to (1), the leading edge surfaces 15 of two connection plate portions 13 adjacent to each other in the first direction in the same waveform structure 10A or 10C are inclined in opposite directions along the plate thickness direction.
In the offset fin 3 having the above-described configuration, in the leading edge surfaces 15 of the two connection plate portions 13 adjacent to each other in the first direction, the fluid flows in opposite directions along the plate thickness direction of the bonding plate portions 11 and 12. Therefore, a complex swirling flow can occur between two connection plate portions 13. As a result, it is possible to further improve the heat transfer performance between the fluid and the offset fin 3.
(3) According to a third aspect, in the offset fin 3 according to (1) or (2), a connection portion between the first bonding plate portion 11 and the connection plate portion 13 is rounded such that the first bonding plate portion 11 and the connection plate portion 13 are smoothly connected to each other, and a connection portion between the second bonding plate portion 12 and the connection plate portion 13 is rounded such that the second bonding plate portion 12 and the connection plate portion 13 are smoothly connected to each other.
In the offset fin 3 having the above-described configuration, the connection portions between the first and second bonding plate portions 11 and 12 and the connection plate portion 13 are rounded. Therefore, it is possible to suppress the accumulation of the fluid in the vicinity of the connection portion. In addition, it is possible to suppress the obstruction of the swirling flow occurring due to the leading edge surface 15 of the connection plate portion 13 or the like by the connection portion. Therefore, it is possible to suppress or prevent the deterioration of the heat transfer performance between the fluid and the offset fin 3 in the vicinity of the connection portion.
(4) According to a fourth aspect, in the offset fin 3 according to any one of (1) to (3), the plurality of waveform structures 10 are located to deviate from each other in the first direction, as viewed from the second direction, such that a plurality of the first bonding plate portions 11 are arranged in the first direction without gaps and a plurality of the second bonding plate portions 12 are arranged in the first direction without gaps.
In the offset fin 3 having the above-described configuration, the level difference caused by the first bonding plate portion 11 and the second bonding plate portion 12 in the second direction appears at any position in the first direction. Therefore, when the fluid flows through the offset fin 3 in the second direction, turbulence caused by the level difference occurs at any position in the first direction. As a result, the development of the thermal boundary layer is suppressed at any position in the first direction. Therefore, it is possible to improve the heat transfer performance between the fluid and the offset fin 3 over the entire offset fin 3.
(5) According to a fifth aspect, in the offset fin 3 according to (4), the connection plate portion 13, the first bonding plate portion 11, the connection plate portion 13, and the second bonding plate portion 12 that are arranged in order in the first direction in the same waveform structure 10 form one period, and the plurality of waveform structures 10 that are continuous in the second direction deviate toward a first side in the first direction by 1/4 of the period.
In the offset fin 3 having the above-described configuration, the plurality of first bonding plate portions 11 can be arranged in the first direction without gaps as viewed from the second direction, and the plurality of second bonding plate portions 12 can be arranged in the first direction without gaps.
(6) According to a sixth aspect, in the offset fin 3 according to any one of (1) to (5), the leading edge surface 17 of each of the first bonding plate portion 11 and the second bonding plate portion 12 that faces the first side in the second direction has the inclined surfaces 171 and 172 that are inclined toward a second side in the second direction with respect to the first direction.
In the offset fin 3 having the above-described configuration, when the fluid flows to the second side in the second direction through the offset fin 3, the swirling flow (secondary flow) occurs due to the flow of the fluid along the inclined surfaces 171 and 172 of the leading edge surface 17 of each of the first and second bonding plate portions 11 and 12. Therefore, it is possible to suppress the development of the thermal boundary layer appearing on the surface along the flow direction of the fluid such as the main surfaces of the first and second bonding plate portions 11 and 12. That is, the thickness of the thermal boundary layer can be suppressed to be small. As a result, it is possible to improve the heat transfer performance between the fluid and the offset fin 3.
(7) According to a seventh aspect, there is provided the heat exchanger 1 including: the offset fin 3 according to any one of (1) to (6); and a pair of plates 2 configured to be disposed with the offset fin 3 interposed therebetween in the plate thickness direction, in which the first bonding plate portion 11 is overlapped and bonded to the first plate 2A of the pair of plates 2, and the second bonding plate portion 12 is overlapped and bonded to the second plate 2B of the pair of plates 2.
In the heat exchanger 1 having the above-described configuration, when the fluid flows to the second side in the second direction between the pair of plates 2, a swirling flow occurs due to the leading edge surface 15 of the connection plate portion 13 of the offset fin 3. Therefore, it is possible to suppress the development of the thermal boundary layer appearing on a surface along the flow direction of the fluid such as the main surfaces of the first and second plates 2A and 2B. Therefore, it is possible to improve the heat transfer performance between the fluid and the offset fin 3.
(8) According to an eighth aspect, there is provided the plate material 100 for a fin having a single plane, the plate material 100 for a fin including: a plurality of unit structures 110 each of which includes the first bonding plate portion 11 and the second bonding plate portion 12 that are alternately arranged at intervals in a first direction along the plane and a plurality of connection plate portions 13 each of which is disposed between the first bonding plate portion 11 and the second bonding plate portion 12 in the first direction and connects the first bonding plate portion 11 and the second bonding plate portion 12, in which the plurality of unit structures 110 are arranged in a second direction perpendicular to the first direction along the plane, two unit structures 110 that are adjacent to each other in the second direction are located to deviate from each other in the first direction, in at least one of the unit structures 110, the leading edge surface 15 of the connection plate portion 13 that faces a first side in the second direction is inclined toward a second side in the second direction with respect to the first direction, and, in the same unit structure 110, the first boundary line 141 between the first bonding plate portion 11 and the connection plate portion 13 and the second boundary line 142 between the second bonding plate portion 12 and the connection plate portion 13 extend without being inclined with respect to the second direction.
- The offset fin 3 can be manufactured by folding the plate material 100 for a fin having the above-described configuration at the first boundary line 141 between the first bonding plate portion 11 and the connection plate portion 13 and at the second boundary line 142 between the second bonding plate portion 12 and the connection plate portion 13.
- In addition, since the first and second boundary lines 141 and 142 are not inclined with respect to the second direction, it is possible to fold the plate material 100 for a fin at the first and second boundary lines 141 and 142 without changing the orientation (angle) of the plate material 100 for a fin. As a result, it is possible to suppress or prevent the occurrence of manufacturing errors based on the change in the orientation of the plate material 100 for a fin.
(9) According to a ninth aspect, there is provided a method for manufacturing the offset fin 3 using the plate material 100 for a fin according to (8), the method including folding the plate material 100 for a fin in a valley fold at the first boundary line 141 and folding the plate material 100 for a fin in a mountain fold at the second boundary line 142.

According to the method for manufacturing the offset fin 3, it is possible to manufacture the offset fin 3.
In addition, since the first and second boundary lines 141 and 142 are not inclined with respect to the second direction, it is possible to fold the plate material 100 for a fin at the first and second boundary lines 141 and 142 without changing the orientation (angle) of the plate material 100 for a fin. As a result, it is possible to suppress or prevent the occurrence of manufacturing errors based on the change in the orientation of the plate material 100 for a fin.

REFERENCE SIGNS LIST

1 Heat exchanger
2 Plate
2A First plate
2B Second plate
3 Offset fin
10 Waveform structure
10A First waveform structure
10B Second waveform structure
10C Third waveform structure
10D Fourth waveform structure
11 First bonding plate portion
12 Second bonding plate portion
13 Connection plate portion
15 Leading edge surface of connection plate portion 13
17 Leading edge surface of bonding plate portions 11 and 12
100 Plate material for fin
110 Unit structure
110A First unit structure
110B Second unit structure
110C Third unit structure
110D Fourth unit structure
141 First boundary line
142 Second boundary line
171 First inclined surface
172 Second inclined surface

Claims

An offset fin comprising:
a plurality of waveform structures configured to extend in a first direction perpendicular to a plate thickness direction while periodically meandering in the plate thickness direction, each of the waveform structures including a first bonding plate portion and a second bonding plate portion that are located to deviate from each other in the plate thickness direction and are alternately arranged in the first direction and a plurality of connection plate portions each of which extends in the plate thickness direction and connects the first bonding plate portion and the second bonding plate portion adjacent to each other in the first direction and which are arranged at intervals in the first direction,

wherein the plurality of waveform structures are arranged in a second direction perpendicular to the plate thickness direction and the first direction,

the connection plate portions in two waveform structures adjacent to each other in the second direction are located to deviate from each other in the first direction, and

in at least one of the waveform structures, a leading edge surface of the connection plate portion that faces a first side in the second direction is inclined toward a second side in the second direction with respect to the plate thickness direction.
The offset fin according to Claim 1,
wherein the leading edge surfaces of two connection plate portions adjacent to each other in the first direction in the same waveform structure are inclined in opposite directions along the plate thickness direction.
The offset fin according to Claim 1 or 2,
wherein a connection portion between the first bonding plate portion and the connection plate portion is rounded such that the first bonding plate portion and the connection plate portion are smoothly connected to each other, and

a connection portion between the second bonding plate portion and the connection plate portion is rounded such that the second bonding plate portion and the connection plate portion are smoothly connected to each other.
The offset fin according to Claim 1 or 2,
wherein the plurality of waveform structures are located to deviate from each other in the first direction, as viewed from the second direction, such that a plurality of the first bonding plate portions are arranged in the first direction without gaps and a plurality of the second bonding plate portions are arranged in the first direction without gaps.
The offset fin according to Claim 4,
wherein the connection plate portion, the first bonding plate portion, the connection plate portion, and the second bonding plate portion that are arranged in order in the first direction in the same waveform structure form one period, and

the plurality of waveform structures that are continuous in the second direction deviate toward a first side in the first direction by 1/4 of the period.
The offset fin according to Claim 1 or 2,
wherein a leading edge surface of each of the first bonding plate portion and the second bonding plate portion that faces the first side in the second direction has an inclined surface that is inclined toward a second side in the second direction with respect to the first direction.
A heat exchanger comprising:
the offset fin according to Claim 1 or 2; and

a pair of plates configured to be disposed with the offset fin interposed therebetween in the plate thickness direction,

wherein the first bonding plate portion is overlapped and bonded to a first plate of the pair of plates, and

the second bonding plate portion is overlapped and bonded to a second plate of the pair of plates.
A plate material for a fin having a single plane, the plate material for a fin comprising:
a plurality of unit structures each of which includes a first bonding plate portion and a second bonding plate portion that are alternately arranged at intervals in a first direction along the plane and a plurality of connection plate portions each of which is disposed between the first bonding plate portion and the second bonding plate portion in the first direction and connects the first bonding plate portion and the second bonding plate portion,

wherein the plurality of unit structures are arranged in a second direction perpendicular to the first direction along the plane,

two unit structures that are adjacent to each other in the second direction are located to deviate from each other in the first direction,

in at least one of the unit structures, a leading edge surface of the connection plate portion that faces a first side in the second direction is inclined toward a second side in the second direction with respect to the first direction, and

in the same unit structure, a first boundary line between the first bonding plate portion and the connection plate portion and a second boundary line between the second bonding plate portion and the connection plate portion extend without being inclined with respect to the second direction.
An offset fin manufacturing method for manufacturing an offset fin using the plate material for a fin according to Claim 8, the offset fin manufacturing method comprising:
folding the plate material for a fin in a valley fold at the first boundary line and folding the plate material for a fin in a mountain fold at the second boundary line.