Inner fin

Abstract

This inner fin is configured from a plurality of protrusions that are continuous in the width direction, the plurality of protrusions extending in the flow-path direction. The protrusions have contact parts that contact one of two plate parts, the contact parts extending linearly along the flow-path direction. The protrusions have wave-form shapes that vary regularly in a period T along the flow-path direction as seen from the planar direction orthogonal to the flow-path direction and the width direction. The shape of a cross-section orthogonal to the flow-path direction in the protrusions has a first section that rises from the other of the two plate parts toward the one of the two plate parts and reaches the contact part, and a second section that falls from the contact part toward the other of the two plate parts. Within the cross-sectional shape of the protrusions in a reference cross-section and in a portion obtained by removing a cross-section at a site represented by period T / 2 from the reference cross-section, the curvature at a site configured from a curve that reaches the contact part in the first section and the curvature at a site configured from a curve that extends from the contact part in the second section are different from one another.

Description

TECHNICAL FIELD 5

[0001] The present disclosure relates to an inner fin to be disposed between two plate portions facing each other and incorporated in a heat exchanger. BACKGROUND ART

[0002] Patent Literature 1 discloses an inner fin to be inserted into a flat tube incorporated 10 in a heat exchanger, and in which a flow path having a rectangular cross section orthogonal to a flow of exhaust gas is formed to meander as it advances in a longitudinal direction.

[0003] Patent Literature 2 discloses an inner fin to be inserted into a flat tube incorporated in a heat exchanger, and in which a flow path having a corrugated cross section orthogonal to a flow of exhaust gas has a wall surface of a bellows structure that rises and falls in a lateral 15 direction in an uneven manner as it advances in a longitudinal direction. [0003a] It is desired to address or alleviate one or more disadvantages or limitations of the prior art, or to at least provide a useful alternative. CITATION LIST 20 PATENT LITERATURE

[0004] Patent Literature 1: JP2004-263616A Patent Literature 2: JP2008-096048A SUMMARY OF INVENTION 25   [0004a] One or more embodiments of the present invention comprise an inner fin to be disposed between two plate portions facing each other and incorporated in a heat exchanger, the inner fin comprising: a plurality of protrusions that extend in a flow path direction and are continuous in a width direction, 30             wherein the protrusions each have a contact portion that extends linearly along the flow path direction and is in contact with one of the two plate portions, wherein the protrusions have a wave shape that changes regularly at a period T along the flow path direction when viewed from a plane direction orthogonal to the flow path direction 2023354793   10 Jul 2026 and the width direction, wherein a shape of a cross section orthogonal to the flow path direction of the protrusion has a first portion that rises from the other of the two plate portions toward the one of the two plate portions and reaches the contact portion, and a second portion that falls from 5 the contact portion toward the other of the two plate portions, and wherein when a cross section in which a shape of the first portion and a shape of the second portion are line-symmetric is referred to as a reference cross section, regarding the shape of the cross section of the protrusion excluding the reference cross section and a cross section of a portion a period T / 2 away from the reference cross section, 10 a curvature of a portion of the first portion formed by a curve leading to the contact portion is different from a curvature of a portion of the second portion formed by a curve extending from the contact portion. BRIEF DESCRIPTION OF THE DRAWINGS 15

[0005] One or more embodiments of the present invention are hereinafter described, by way of example only, with reference to the accompanying drawings, in which: FIG. 1 is a perspective view illustrating a configuration of a heat exchanger using an inner fin according to the present embodiment. FIG. 2 is a front view illustrating a configuration of a tube and the inner fin. 20             FIG. 3 is a perspective view showing a configuration example of the inner fin. FIG. 4 is a plan view showing the configuration example of the inner fin. FIG. 5 is an enlarged view of a part V in FIG. 4. FIG. 6 is a cross-sectional view of a protrusion at positions A and I in FIG. 5. FIG. 7 is a cross-sectional view of a protrusion at positions B and H in FIG. 5. 25             FIG. 8 is a cross-sectional view of a protrusion at positions C and G in FIG. 5. FIG. 9 is a cross-sectional view of a protrusion at positions D and F in FIG. 5. FIG. 10 is a cross-sectional view of a protrusion at a position E in FIG. 5. FIG. 11 is a view showing a part of the inner fin in FIG. 2. FIG. 12 is a cross-sectional end view showing a configuration of a cross section taken 30 along line XIII-XIII in FIG. 2 as viewed from an arrow direction. FIG. 13 is a partial cross-sectional view of the inner fin at the position A in FIG. 5. 2023354793   10 Jul 2026 DESCRIPTION OF EMBODIMENTS

[0006] In the inner fin according to Patent Literature 1, since an end surface having a rectangular cross section serves as a contact portion that comes into contact with an inner wall surface of the tube, a contact area of the contact portion with respect to the inner wall surface 5 of the tube is large, and a range in which the inner fin is brazed to the inner wall surface of the tube is wide. In this regard, in Patent Literature 2, since a bent portion having a corrugated cross section serves as a contact portion that comes into contact with an inner wall surface of the tube, a contact area of the contact portion with the inner wall surface of the tube is set to a contact area that allows brazing, and a brazing range is limited to an extremely narrow range. However, 10 in Patent Literature 2, a cross-sectional area orthogonal to the flow of the exhaust gas in a portion near the contact portion of each flow path is smaller than a cross-sectional area in other portions. Compared to other portions, the exhaust gas flows less easily and a heat exchange rate is lower.

[0007] The present disclosure is directed to an inner fin with improved heat exchange 15 efficiency.

[0008] To achieve the above, an aspect of the present disclosure provides an inner fin to be disposed between two plate portions facing each other and incorporated in a heat exchanger, the inner fin including: a plurality of protrusions that extend in a flow path direction and are continuous in a 20 width direction, in which the protrusions each have a contact portion that extends linearly along the flow path direction and is in contact with one of the two plate portions, the protrusions have a wave shape that changes regularly at a period T along the flow path direction when viewed from a plane direction orthogonal to the flow path direction and the 25 width direction, a shape of a cross section orthogonal to the flow path direction of the protrusion has a first portion that rises from the other of the two plate portions toward the one of the two plate portions and reaches the contact portion, and a second portion that falls from the contact portion toward the other of the two plate portions, and 30             when a cross section in which a shape of the first portion and a shape of the second portion are line-symmetric is referred to as a reference cross section, regarding the shape of the cross section of the protrusion excluding the reference cross section and a cross section of a portion period T / 2 away from the reference cross section, 2023354793   10 Jul 2026 a curvature of a portion of the first portion formed by a curve leading to the contact portion is different from a curvature of a portion of the second portion formed by a curve extending from the contact portion.

[0009] According to the present disclosure, an inner fin with improved heat exchange efficiency is provided.

[0010] Embodiments will be described in detail below with reference to the accompanying drawings. In each drawing used in the following description, the scale is appropriately changed in order to make each element recognizable. In the drawings, an arrow U indicates an upward direction of the illustrated structure. An arrow D indicates a downward direction of the illustrated structure. An arrow F indicates a forward direction of the illustrated structure. An arrow B indicates a rearward direction of the illustrated structure. An arrow R indicates a right direction of the illustrated structure. An arrow L indicates a left direction of the illustrated structure. These directions are relative directions set for an inner fin 10 shown in FIG. 3, and the direction in which the exhaust gas flows is the forward direction.

[0011] FIG. 1 illustrates a heat exchanger 20 for an exhaust gas recirculation (EGR) system using the inner fin 10 according to the present embodiment. As illustrated in FIG. 1, a plurality of flat tubes 22 are incorporated in a shell 21 of the heat exchanger 20. The inner fin 10 is inserted into each tube 22.

[0012] At both ends of the shell 21, an inlet header 23 for supplying exhaust gas to the tubes 22 and an outlet header 24 for leading out the exhaust gas that has passed through the tubes 22 are attached, respectively. An inlet pipe 25 for supplying cooling water is connected to an inlet side of the shell 21. An outlet pipe 26 for leading out the cooling water is connected to an outlet side of the shell 21. The exhaust gas supplied to the tubes 22 branches into the plurality of tubes 22 and passes through the insides of the tubes 22, and the cooling water flows between the outside of the tubes 22 and the shell 21. Therefore, the exhaust gas is cooled by heat exchange with the cooling water.

[0013] As illustrated in FIG. 2, the tube 22 includes a flat plate-shaped upper plate portion 221, a flat plate-shaped lower plate portion 222, and a side plate portion 223 that connects the upper plate portion 221 and the lower plate portion 222. The inner fin 10 is provided inside the tube 22. That is, the inner fin 10 is disposed between the upper plate portion 221 and the lower plate portion 222 that face each other. Inside the tube 22, a plurality of flow paths 224 through which the exhaust gas passes are formed by the inner fin 10 along a longitudinal direction (in this example, a front-rear direction) of the tube 22. 2023354793   10 Jul 2026

[0014] As illustrated in FIG. 3, the inner fin 10 has a plurality of protrusions 11 extending in a direction in which the flow paths 224 are formed (hereinafter, referred to as a flow path direction A1). The plurality of protrusions 11 are formed to be continuous in a width direction A2 (in this example, a left-right direction). FIG. 3 illustrates a state in which five protrusions 11 extending in the flow path direction A1 are formed side by side in the width direction A2 in a state of protruding upward. The inner fin 10 is formed by processing a single plate material such as SUS (stainless steel) by press molding or the like.

[0015] Each protrusion 11 has a contact portion 111 that comes into contact with the tube 22 at an upper end. The contact portion 111 extends linearly along the flow path direction A1. As illustrated in FIG. 2, the contact portion 111 is brazed to the upper plate portion 221 of the tube 22. Further, each protrusion 11 has a contact portion 112 that comes into contact with the tube 22 at a lower end. The contact portion 112 extends linearly along the flow path direction A1. As illustrated in FIG. 2, the contact portion 112 is brazed to the lower plate portion 222 of the tube 22. By brazing the contact portions 111 and the contact portions 112 of the protrusions 11 to the tube 22 in this manner, the plurality of flow paths 224 extending along the longitudinal direction of the tube 22 and continuously arranged in the width direction (the left-right direction in this example) of the tube 22 are formed.

[0016] As illustrated in FIG. 4, each protrusion 11 has a wave shape that changes regularly at a period T along the flow path direction when viewed from a plane direction (in this example, from above) orthogonal to the flow path direction A1 and the width direction A2.

[0017] Hereinafter, the wave shape of the protrusion 11 will be described in detail with reference to FIGS. 5 to 10. FIG. 5 is an enlarged view of a part V in FIG. 4. FIGS. 6 to 10 illustrate shapes of cross sections of the protrusion 11 orthogonal to the flow path direction A1 at positions A to I in the period T shown in FIG. 5. Specifically, FIG. 6 illustrates shapes of cross sections of the protrusion 11 at positions A and I. FIG. 7 illustrates shapes of cross sections of the protrusion 11 at positions B and H. FIG. 8 illustrates shapes of cross sections of the protrusion 11 at positions C and G. FIG. 9 illustrates shapes of cross sections of the protrusion 11 at positions D and F. FIG. 10 illustrates a shape of a cross section of the protrusion 11 at a position E. The positions A to I indicate positions that differ by T / 8 each.

[0018] As illustrated in FIG. 6, the shape of the cross section of the protrusion 11 includes a first portion 113 and a second portion 114. The first portion 113 rises from an inner wall surface 222A of the lower plate portion 222 of the tube 22 toward an inner wall surface 221A of the upper plate portion 221 and reaches the contact portion 111. The second portion 114 falls from 2023354793   10 Jul 2026 the contact portion 111 toward the inner wall surface 222A of the lower plate portion 222 of the tube 22.

[0019] The first portion 113 has a portion 1131 formed as a curve leading to the contact portion 111. The portion 1131 has a first curvature radius R1. The first curvature radius R1 of the portion 1131, that is, the curvature of the portion 1131, changes regularly at the period T along the flow path direction A1.

[0020] Specifically, as shown in FIGS. 6 to 10, from the position A to the position E, the portion 1131 is formed such that the first curvature radius R1 decreases along the flow path direction A1, that is, the curvature increases along the flow path direction A1. On the other hand, as shown in FIGS. 10 to 6, from the position E to the position I, the portion 1131 is formed such that the first curvature radius R1 increases along the flow path direction A1, that is, the curvature decreases along the flow path direction A1.

[0021] The second portion 114 has a portion 1141 formed as a curve extending from the contact portion 111. The portion 1141 has a second curvature radius R2. The second curvature radius R2 of the portion 1141, that is, the curvature of the portion 1141, changes regularly at the period T along the flow path direction A1.

[0022] Specifically, as shown in FIGS. 6 to 10, from the position A to the position E, the portion 1141 is formed such that the second curvature radius R2 increases along the flow path direction A1, that is, the curvature decreases along the flow path direction A1. On the other hand, as shown in FIGS. 10 to 6, from the position E to the position I, the portion 1141 is formed such that the second curvature radius R2 decreases along the flow path direction A1, that is, the curvature increases along the flow path direction A1.

[0023] As illustrated in FIG. 8, the shapes of the first portion 113 and the second portion 114 are line-symmetric at the positions C and G, and the first curvature radius R1 and the second curvature radius R2 have the same value. When the cross section of the protrusion 11 at the position C is referred to as a reference cross section, regarding the shapes of the cross sections of the protrusion 11 excluding the reference cross section and the cross section of the protrusion 11 at the position G, as illustrated in FIGS. 6, 7, 9, and 10, the curvature of the portion 1131 of the first portion 113 is different from the curvature of the portion 1141 of the second portion 114.

[0024] For example, at the position A and the position B, the first curvature radius R1 is larger than the second curvature radius R2. At the position C, the first curvature radius R1 becomes equal to the second curvature radius R2. At the position D, the position E, and the 2023354793   10 Jul 2026 position F, the first curvature radius R1 is smaller than the second curvature radius R2. At the position G, the first curvature radius R1 becomes equal to the second curvature radius R2. At the position H and the position I, the first curvature radius R1 is larger than the second curvature radius R2.

[0025] The first curvature radius R1 and the second curvature radius R2 are set to, for example, 0.2 mm or more. In addition, the first curvature radius R1 and the second curvature radius R2 are set, for example, such that the curvature radius on the larger side is equal to or smaller than twice the curvature radius on the smaller side in the same cross section. For example, when a fin pitch P (FIG. 6) is 6 mm, the first curvature radius R1 and the second curvature radius R2 are set such that one curvature radius is 0.4 mm and the other curvature radius is 2.4 mm. The fin pitch P is a distance between adjacent protrusions 11.

[0026] Here, in order to narrow a brazing range of the contact portion 111 with respect to the tube 22, for example, as in the inner fin according to Patent Literature 2, it is conceivable to reduce the curvature radius of a bent portion which is the contact portion. However, in the vicinity of the bent portion, a cross-sectional area orthogonal to the flow path direction is smaller than a cross-sectional area of other portions, and the heat exchange rate is low.

[0027] In this regard, according to the inner fin 10 of the present embodiment, the curvature of the portion 1131 of the first portion 113 and the curvature of the portion 1141 of the second portion 114 are different at positions other than the positions C and G. In other words, a curved surface including the contact portion 111 does not have a single curvature radius, but is formed to have different curvature radii on both sides of the contact portion 111. Therefore, it is possible to prevent the cross-sectional area in the vicinity of the contact portion 111 from being smaller than that of other portions. Accordingly, the exhaust gas flows easily through the entire area of the cross section of the protrusion 11, and the heat exchange efficiency of the inner fin 10 as a whole is improved.

[0028] In addition, since the contact portion 111 extends linearly along the flow path direction A1, for example, when forming a plurality of inner fins 10 on a plate material and then cutting the plate material into individual inner fins 10 at the contact portion 111, the contact portion 111 can be easily cut. In addition, since the cut end portions of the inner fins 10 are linear, the inner fins can be easily insert into the tube 22 compared to one having a meandering end portion.

[0029] In the present embodiment, as illustrated in FIG. 2, the contact portions 111 and 112 are configured to be in line contact with the tube 22. Specifically, the contact portion 111 is in 2023354793   10 Jul 2026 line contact with the inner wall surface of the upper plate portion 221 of the tube 22. The contact portion 112 is in line contact with the inner wall surface of the lower plate portion 222 of the tube 22. According to such a configuration, an amount of brazing material used can be reduced as compared with a case where the contact portion 111 is in surface contact with the tube 22.

[0030] In the present embodiment, as illustrated in FIG. 11, the inner fin 10 is configured such that a gap g is provided between the protrusion 11 and the protrusion 11 adjacent to each other when viewed from the flow path direction A1. Specifically, the maximum distance L1 from the contact portion 111 to the first portion 113 in the width direction A2 is smaller than P / 2. Further, the maximum distance L2 from the contact portion 111 to the second portion 114 in the width direction is smaller than P / 2. According to such a configuration, since the flow path penetrating in the flow path direction A1 that is not blocked by the protrusion 11 is provided, the heat exchange rate can be increased.

[0031] In the present embodiment, as illustrated in FIG. 12, a cross section (in this example, a planar cross section) of the protrusions 11 orthogonal to the flow path direction A1 and the width direction A2 is configured to have a wave shape formed by curves. Specifically, a shape of the planar cross section of the protrusions 11 includes a third portion 115 having a wave shape and a fourth portion 116 having a wave shape. The third portion 115 has a curved portion 115R1 that protrudes to the inside (left side in this example) of the protrusion 11 and a curved portion 115R2 that protrudes to the outside (right side in this example) of the protrusion 11. The fourth portion 116 has a curved portion 116R1 that protrudes to the inside (right side in this example) of the protrusion 11 and a curved portion 116R2 that protrudes to the outside (left side in this example) of the protrusion 11. The curvature radius of the curved portion 115R1, 115R2 of the third portion 115 and the curvature radius of the curved portion 116R1, 116R2 of the fourth portion 116 are set to, for example, 1 mm or more.

[0032] Here, by meandering the protrusions 11 left and right along the flow path direction A1, a surface area of the protrusion 11 increases, and the heat exchange efficiency is improved. However, when the exhaust gas flowing through the flow path 224 in the protrusion 11 passes over a protruding portion that protrudes to the inside of the flow path 224, a return vortex is generated in a recessed portion, and the return vortex causes soot or the like contained in the exhaust gas to remain and accumulate on the wall surface.

[0033] One approach to this problem is to intentionally generate a vortex by forming the shape of the planar cross section into a bellows structure with a triangular waveform having pointed ends. However, the inventor of the present invention has found that, rather than 2023354793   10 Jul 2026 intentionally generating a vortex, making the shape of the planar cross section into a gently curved, wavy shape prevents the soot from accumulating and allows the soot to flow more easily.

[0034] That is, according to the inner fin 10 of the present embodiment, since the shape of the planar cross section of the protrusion 11 is a wave shape formed by a curve including the curved portion 115R1, 115R2, 116R1, 116R2, it is possible to prevent the soot from accumulating, allow the soot to flow more easily, and prevent the soot from adhering.

[0035] Further, in the present embodiment, as illustrated in FIG. 13, the first portion 113 of the protrusion 11 has a portion 1132 formed as a curve leading to the contact portion 112. The portion 1132 has a third curvature radius R3. The third curvature radius R3 has the same value as the second curvature radius R2 and changes regularly at the period T along the flow path direction A1. The second portion 114 of the protrusion 11 has a portion 1142 formed as a curve leading to the contact portion 112. The portion 1142 has a fourth curvature radius R4. The fourth curvature radius R4 has the same value as the first curvature radius R1 and changes regularly at the period T along the flow path direction A1. According to such a configuration, a lower space sandwiched between adjacent protrusions 11 is widened, so that the exhaust gas easily flows in the entire area of the cross section of the space sandwiched between the adjacent protrusions 11, and the heat exchange efficiency of the inner fin 10 as a whole is improved.

[0036] The above embodiment is merely an example for facilitating understanding of the present invention. The configuration according to the above embodiment may be appropriately modified or improved without departing from the gist of the present invention.

[0037] In the above embodiment, the heat exchanger 20 is a heat exchanger for an exhaust gas recirculation (EGR) system that cools exhaust gas with cooling water. However, the heat exchanger 20 may be used, for example, as a heat exchanger that cools a fluid other than the exhaust gas.

[0038] In the above embodiment, the plurality of inner fins 10 are respectively inserted into the plurality of tubes 22 incorporated in the heat exchanger 20. However, the heat exchanger 20 may have, for example, a configuration in which partition plates and the inner fins 10 are alternately stacked. That is, the heat exchanger 20 may also have a configuration in which the inner fins 10 are disposed between two partition plates (an example of two plate portions) that face each other. In this case, connecting plates that connect the two partition plates may be formed on both end sides of the inner fin 10 in the left-right direction.

[0039] The present application is based on a Japanese patent application (Japanese Patent Application No. 2022-157808) filed on September 30, 2022, contents of which are incorporated 2023354793   10 Jul 2026 herein by reference.

[0040] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but 5 not the exclusion of any other integer or step or group of integers or steps.

[0041] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to 10 which this specification relates.

Claims

1. An inner fin to be disposed between two plate portions facing each other and incorporated in a heat exchanger, the inner fin comprising:5             a plurality of protrusions that extend in a flow path direction and are continuous in awidth direction,wherein the protrusions each have a contact portion that extends linearly along the flow path direction and is in contact with one of the two plate portions,wherein the protrusions have a wave shape that changes regularly at a period T along10 the flow path direction when viewed from a plane direction orthogonal to the flow path direction and the width direction,wherein a shape of a cross section orthogonal to the flow path direction of the protrusion has a first portion that rises from the other of the two plate portions toward the one of the two plate portions and reaches the contact portion, and a second portion that falls from 15 the contact portion toward the other of the two plate portions, andwherein when a cross section in which a shape of the first portion and a shape of the second portion are line-symmetric is referred to as a reference cross section,regarding the shape of the cross section of the protrusion excluding the reference cross section and a cross section of a portion a period T / 2 away from the reference cross section, 20 a curvature of a portion of the first portion formed by a curve leading to the contact portion is different from a curvature of a portion of the second portion formed by a curve extending from the contact portion.

2. The inner fin according to claim 1,25             wherein from a portion with the reference cross section to a portion the period T / 4away from the reference cross section,the curvature of the portion of the first portion formed by the curve leading to the contact portion increases along the flow path direction, andthe curvature of the portion of the second portion formed by the curve extending from 30 the contact portion decreases along the flow path direction.

3. The inner fin according to claim 1,wherein the contact portion is in line contact with one of the two plate portions.2023354793   10 Jul 2026

4. The inner fin according to claim 1,wherein a gap is provided between the protrusion and the protrusion adjacent to each other when viewed from the flow path direction.5

5. The inner fin according to claim 1,wherein a cross section of the protrusion orthogonal to the flow path direction and the width direction has a wave shape formed by a curve.

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