Inner fin

Abstract

The inner fins are configured by a plurality of protrusions extending in the flow path direction being continuous in the width direction. The protrusion has a contact portion that extends linearly in the flow path direction and that contacts one of the two plate portions. When viewed from a plane orthogonal to the flow path direction and the width direction, the protrusions have a wave shape that varies regularly at a period T along the flow path direction. The shape of the cross-section of the protrusion that is orthogonal to the flow path direction has a first portion that rises from the other of the two plate portions toward 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. With respect to the shape of the cross-section of the protrusion in a portion other than the reference cross-section and a cross-section at a period T / 2 from the reference cross-section, the curvature of a portion of the first portion constituted by a curved line reaching the contact portion is different from the curvature of a portion of the second portion constituted by a curved line extending from the contact portion.

Description

Technical Field

[0001] The present disclosure relates to an inner fin disposed between two opposing plate portions assembled in a heat exchanger. Background Art

[0002] Patent Document 1 discloses an inner fin inserted into a flat tube assembled in a heat exchanger, wherein a flow path of the inner fin having a rectangular cross-sectional shape perpendicular to the flow of exhaust gas is formed to meander as it advances in the longitudinal direction.

[0003] Patent Document 2 discloses an inner fin inserted in a flat tube assembled in a heat exchanger, wherein a flow path of the inner fin having a corrugated cross-sectional shape perpendicular to the flow of exhaust gas has a wall surface with a corrugated structure that undulates in a convex-concave shape in the lateral direction as it goes in the longitudinal direction.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2004-263616

[0007] Patent Document 2: Japanese Patent Application Publication No. 2008-96048 Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] In the inner fin of Patent Document 1, since the end face with a rectangular cross-sectional shape becomes the contact portion that abuts against the inner wall surface of the tube, the contact area of ​​the contact portion relative to the inner wall surface of the tube is large, and the range of brazing the inner fin to the inner wall surface of the tube is wide. In contrast, in Patent Document 2, since the curved portion with a corrugated cross-sectional shape becomes the contact portion that abuts against the inner wall surface of the tube, the contact area of ​​the contact portion relative to the inner wall surface of the tube is set to a contact area that can be brazed, and the brazing range is limited to an extremely narrow range. However, in Patent Document 2, in the portion of each flow path close to the contact portion, the cross-sectional area orthogonal to the flow of the exhaust gas is smaller than the cross-sectional area of ​​other portions, and the exhaust gas is difficult to flow compared to other portions, and the heat exchange rate becomes low.

[0010] An object of the present disclosure is to provide an inner fin with improved heat exchange efficiency.

[0011] Technical means for solving technical problems

[0012] One method for achieving the above object is to arrange an inner fin between two opposing plate portions assembled in a heat exchanger.

[0013] The inner fin is composed of a plurality of protrusions extending in the flow path direction and continuous in the width direction.

[0014] The protrusion has a contact portion extending linearly along the flow path direction and contacting one of the two plate portions.

[0015] The protrusion is in a wave shape that changes regularly with a period T along the flow path direction when viewed from a plane perpendicular to the flow path direction and the width direction.

[0016] The shape of the cross section of the protrusion orthogonal to the flow path direction includes a first portion and a second portion, wherein the first portion rises from the other of the two plate portions toward the one of the two plate portions and reaches the contact portion, and the second portion descends from the contact portion toward the other of the two plate portions.

[0017] When the cross-section in which the shapes of the first part and the second part are linearly symmetrical is called a reference cross-section, with respect to the shape of the cross-section of the protrusion excluding the reference cross-section and the cross-section at a portion that is period T / 2 away from the reference cross-section, the curvature of the portion of the first part formed by the curve reaching the contact portion is different from the curvature of the portion of the second part formed by the curve extending from the contact portion.

[0018] Effects of the Invention

[0019] According to the present disclosure, an inner fin with improved heat exchange efficiency is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a perspective view illustrating the structure of a heat exchanger using the inner fins according to the present embodiment.

[0021] Figure 2 This is a front view illustrating the structure of the tube and the inner fin.

[0022] Figure 3 It is a perspective view showing a configuration example of an inner fin.

[0023] Figure 4 It is a plan view showing a configuration example of an inner fin.

[0024] Figure 5 yes Figure 4 An enlarged view of the V portion.

[0025] Figure 6 yes Figure 5 Cross-sectional view of the protrusion at positions A and I.

[0026] Figure 7 yes Figure 5 Cross-sectional view of the protrusion at positions B and H.

[0027] Figure 8 yes Figure 5 Cross-sectional view of the protrusion at positions C and G.

[0028] Fig. 9 yes Figure 5 Cross-sectional view of the protrusion at positions D and F.

[0029] Fig.10 yes Figure 5 A cross-sectional view of the protrusion at position E.

[0030] Fig.11 Yes means Figure 2 Figure 4 shows a portion of an inner fin.

[0031] Fig.12 It means that when viewed from the direction of the arrow, Figure 2 An end view of a cut portion showing a cross section taken along line XIII-XIII in FIG.

[0032] Fig.13 yes Figure 5 Partial cross-sectional view of the inner fin at position A. DETAILED DESCRIPTION

[0033] The following detailed description of the implementation example is provided with reference to the accompanying drawings. In the drawings used in the following description, the scale is appropriately changed to make each element a recognizable size. In the drawings, arrow U indicates the upward direction of the illustrated structure. Arrow D indicates the downward direction of the illustrated structure. Arrow F indicates the front direction of the illustrated structure. Arrow B indicates the rear direction of the illustrated structure. Arrow R indicates the right direction of the illustrated structure. Arrow L indicates the left direction of the illustrated structure. These directions are for Figure 3 The inner fins 10 shown are set in the relative direction, with the exhaust gas flow direction being the front direction.

[0034] Figure 1 A heat exchanger 20 for an EGR (Exhaust Gas Recirculation) system using the inner fin 10 of this embodiment is shown as an example. Figure 1 As shown, a plurality of flat tubes 22 are assembled in a housing 21 of a heat exchanger 20. In each tube 22, an inner fin 10 is inserted.

[0035] An inlet header 23 for supplying exhaust gas to the tubes 22 and an outlet header 24 for leading the exhaust gas passing through the tubes 22 are respectively installed at both ends of the shell 21. An inlet pipe 25 for supplying cooling water is connected to the inlet side of the shell 21. An outlet pipe 26 for leading the cooling water is connected to the outlet side of the shell 21. The exhaust gas supplied to the tubes 22 is branched to a plurality of tubes 22 and passes through the inside of the tubes 22, and the cooling water flows between the outside of the tubes 22 and the shell 21, whereby the exhaust gas is cooled by heat exchange with the cooling water.

[0036] like Figure 2 As shown, the tube 22 has a flat plate-shaped upper plate portion 221, a flat plate-shaped lower plate portion 222, and a side plate portion 223 connecting the upper plate portion 221 and the lower plate portion 222. An inner fin 10 is provided inside the tube 22. That is, the inner fin 10 is arranged between the upper plate portion 221 and the lower plate portion 222 that are opposite to each other. Inside the tube 22, a plurality of flow paths 224 for exhaust gas to pass are formed by the inner fin 10 along the longitudinal direction of the tube 22 (in this example, the front-rear direction).

[0037] like Figure 3 As shown, the inner fin 10 has a plurality of protrusions 11 extending in the direction of forming the flow path 224 (hereinafter referred to as the flow path direction A1). The plurality of protrusions 11 are formed to be continuous in the width direction A2 (in this example, the left-right direction). Figure 3 , five protrusions 11 extending in the flow path direction A1 are arranged in the width direction A2 in a state of protruding upward. The inner fin 10 is formed by processing a plate material such as SUS (stainless steel) by press forming or the like.

[0038] Each protrusion 11 has a contact portion 111 at the upper end thereof for contacting the tube 22. The contact portion 111 extends linearly along the flow path direction A1. Figure 2 As shown in the example, the contact portion 111 is brazed to the upper plate portion 221 of the tube 22. In addition, each protrusion 11 has a contact portion 112 at the lower end that contacts the tube 22. The contact portion 112 extends linearly along the flow path direction A1. Figure 2 As shown, the contact portion 112 is brazed to the lower plate portion 222 of the tube 22. In this way, the contact portion 111 and the contact portion 112 of the protrusion 11 are brazed to the tube 22, thereby forming a plurality of flow paths 224 extending along the length direction of the tube 22 and continuously arranged in the width direction of the tube 22 (in this example, the left-right direction).

[0039] like Figure 4 As shown, each protrusion 11 has a wave shape that changes regularly with a period T along the flow path direction when viewed from a plane direction (in this example, upward) that is orthogonal to the flow path direction A1 and the width direction A2.

[0040] Below, use Figures 5 to 10 The wave shape of the protrusion 11 will be described in detail. Figure 5 yes Figure 4 An enlarged view of the V portion. Figure 6 to Figure 10 exemplify Figure 5 The cross-sectional shape of the protrusion 11 at each position A to I within the period T shown is perpendicular to the flow path direction A1. Specifically, Figure 6 The cross-sectional shapes of the protrusion 11 at positions A and I are shown as examples. Figure 7 The cross-sectional shapes of the protrusion 11 at positions B and H are shown as examples. Figure 8 The cross-sectional shapes of the protrusion 11 at positions C and G are shown as examples. Fig. 9 The cross-sectional shapes of the protrusions 11 at positions D and F are shown as examples. Fig.10 The cross-sectional shape of the protrusion 11 at the position E is exemplified. In addition, the positions A to I represent positions that are respectively different from each other by T / 8.

[0041] like Figure 6 As shown, the cross-sectional shape of the protrusion 11 includes a first portion 113 and a second portion 114. The first portion 113 rises from the inner wall surface 222A of the lower plate portion 222 of the tube 22 to the inner wall surface 221A of the upper plate portion 221 and reaches the contact portion 111. The second portion 114 descends from the contact portion 111 to the inner wall surface 222A of the lower plate portion 222 of the tube 22.

[0042] The first portion 113 has a portion 1131 formed of a curve reaching 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 with a period T along the flow path direction A1.

[0043] Specifically, if Figure 6 to Figure 10 As shown, between position A and 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, between position E and position I, as shown Figure 10 to Figure 6 As shown, 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.

[0044] The second portion 114 has a portion 1141 formed of 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 1131 changes regularly with a period T along the flow path direction A1.

[0045] Specifically, if Figures 6 to 10 As shown, the portion 1141 is formed between position A and position E so that the second radius of curvature R2 increases along the flow path direction A1, that is, the curvature decreases along the flow path direction A1. On the other hand, between position E and position I, as shown Figure 10 to Figure 6 As shown, the second curvature radius R2 is formed to decrease along the flow path direction A1, that is, the curvature increases along the flow path direction A1.

[0046] like Figure 8As shown, the shapes of the first portion 113 and the second portion 114 are line symmetrical at positions C and G, and the first radius of curvature R1 and the second radius of curvature R2 have the same value. When the cross section of the protrusion 11 at position C is referred to as a reference cross section, the shape of the cross section of the protrusion 11 other than the reference cross section and the cross section of the protrusion 11 at position G is as follows: Figure 6 , 7 As shown in FIGS. 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 .

[0047] For example, at position A and position B, the first radius of curvature R1 is greater than the second radius of curvature R2. At position C, if the first radius of curvature R1 is the same as the second radius of curvature R2, then at position D, position E, and position F, the first radius of curvature R1 is smaller than the second radius of curvature R2. And, at position G, if the first radius of curvature R1 is the same as the second radius of curvature R2, then at position H and position I, the first radius of curvature R1 is greater than the second radius of curvature R2.

[0048] The first radius of curvature R1 and the second radius of curvature R2 are set to be, for example, 0.2 mm or more. In addition, the first radius of curvature R1 and the second radius of curvature R2 are set to be, for example, twice or less the radius of curvature of the larger side in the same cross section than the radius of curvature of the smaller side. For example, the first radius of curvature R1 and the second radius of curvature R2 are set to be, at the fin interval P( Figure 6 ) is 6 mm, the radius of curvature of one side is 0.4 mm, and the radius of curvature of the other side is 2.4 mm. In addition, the fin interval P is the distance between adjacent protrusions 11.

[0049] Here, in order to narrow the brazing range of the contact portion 111 with respect to the tube 22, it is conceivable to reduce the curvature radius of the curved portion as the contact portion, for example, as in the inner fin of Patent Document 2. However, near the curved portion, the cross-sectional area perpendicular to the flow path direction is smaller than the cross-sectional area of ​​other parts, and the heat exchange rate becomes lower.

[0050] In contrast, according to the inner fin 10 of the present embodiment, at positions other than positions C and G, 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. In other words, the curved surface including the contact portion 111 is not formed with a single curvature radius, but is formed to have different curvature radii across the contact portion 111. Therefore, it is possible to suppress the cross-sectional area near the contact portion 111 from being smaller than other portions. As a result, the exhaust gas easily flows in the entire region of the cross section of the protrusion 11, and the heat exchange efficiency of the inner fin 10 as a whole is improved.

[0051] In addition, since the contact portion 111 extends linearly along the flow path direction A1, it is easy to cut the contact portion 111 when, for example, a plurality of inner fins 10 are formed on a plate and then the contact portion 111 is cut to separate the inner fins 10. In addition, since the end of the cut inner fin 10 is linear, it is easier to insert it into the tube 22 than an inner fin having a meandering end.

[0052] In addition, in this embodiment, if Figure 2 As shown, the contact portions 111 and 112 are configured to be in line contact with the tube 22. Specifically, the contact portion 111 is in 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, the amount of brazing material used can be reduced compared to the case where the contact portion 111 is in surface contact with the tube 22.

[0053] In addition, in this embodiment, if Fig.11 As shown, the inner fin 10 is configured to have a gap g between adjacent protrusions 11 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. Furthermore, 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 a flow path that is not blocked by the protrusion 11 and passes through in the flow path direction A1 is provided, the heat exchange rate can be improved.

[0054] In addition, in this embodiment, if Fig.12 As shown, the cross section (in this example, a plane cross section) of the protrusion 11 that is orthogonal to the flow path direction A1 and the width direction A2 is configured to have a wave shape formed by a curve. Specifically, the shape of the plane cross section of the protrusion 11 has 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 toward the inner side of the protrusion 11 (the left side in this example) and a curved portion 115R2 that protrudes toward the outer side of the protrusion 11 (the right side in this example). The fourth portion 116 has a curved portion 116R1 that protrudes toward the inner side of the protrusion 11 (the right side in this example) and a curved portion 116R2 that protrudes toward the outer side of the protrusion 11 (the left side in this example). The curvature radii of the curved portions 115R1 and 115R2 of the third portion 115 and the curvature radii of the curved portions 116R1 and 116R2 of the fourth portion 116 are set to be, for example, 1 mm or more, respectively.

[0055] Here, by making the protrusion 11 meander left and right along the flow path direction A1, the surface area of ​​the protrusion 11 is increased, and the heat exchange efficiency is improved. However, the exhaust gas flowing in the flow path 224 in the protrusion 11 passes over the convex portion protruding to the inner side of the flow path 224, thereby generating a vortex in the return direction in the concave portion, and there is a problem that soot and the like contained in the exhaust gas are retained by the return vortex and accumulated on the wall surface.

[0056] In order to solve this problem, it is considered that, for example, the vortex flow may be intentionally generated by forming the plane cross section into a corrugated structure with a sharp triangular waveform at the front end. However, the inventors have found that, compared with the intentional generation of the vortex flow, the retention of the soot is suppressed by forming the plane cross section into a wave shape composed of gently curved lines, and the soot flows more easily.

[0057] That is, according to the inner fin 10 of this embodiment, since the planar cross-section of the protrusion 11 is a wave shape formed by the curves formed by the curved portions 115R1, 115R2, 116R1, and 116R2, the accumulation of soot is suppressed, the soot flows easily, and the adhesion of soot can be prevented.

[0058] In addition, in this embodiment, if Fig.13 As shown, the first portion 113 of the protrusion 11 has a portion 1132 formed by a curve reaching the contact portion 112. The portion 1132 has a third radius of curvature R3. The third radius of curvature R3 has the same value as the second radius of curvature R2, and changes regularly with a period T along the flow path direction A1. The second portion 114 of the protrusion 11 has a portion 1142 formed by a curve reaching the contact portion 112. The portion 1142 has a fourth radius of curvature R4. The fourth radius of curvature R4 has the same value as the first radius of curvature R1, and changes regularly with a period T along the flow path direction A1. According to such a configuration, since the lower space sandwiched by adjacent protrusions 11 is expanded, the exhaust gas is easy to flow in the entire area of ​​the cross section of the space sandwiched by adjacent protrusions 11, and the heat exchange efficiency of the inner fin 10 as a whole is improved.

[0059] The above-described embodiment is merely an example for facilitating understanding of the present invention, and the configuration of the above-described embodiment can be appropriately changed or improved without departing from the gist of the present invention.

[0060] In the above embodiment, the heat exchanger 20 is a heat exchanger for an EGR (Exhaust Gas Recirculation) system that cools exhaust gas with cooling water. However, the heat exchanger 20 can also be used as a heat exchanger that cools a fluid different from the exhaust gas, for example.

[0061] In the above embodiment, the plurality of inner fins 10 are respectively inserted into the plurality of tubes 22 assembled in the heat exchanger 20. However, the heat exchanger 20 may have a structure in which the partitions and the inner fins 10 are alternately stacked, for example. That is, the heat exchanger 20 may also adopt a structure in which the inner fins 10 are arranged between two opposing partitions (an example of two plate portions). In this case, a connecting plate connecting the two partitions may be formed on both end sides of the inner fin 10 in the left-right direction.

[0062] This application is based on Japanese Patent Application No. 2022-157808 filed on September 30, 2022, the contents of which are incorporated herein by reference.

Claims

1. An inner fin, which is arranged between two opposing plate parts assembled in a heat exchanger, The inner fin is composed of a plurality of protrusions extending in the flow path direction and continuous in the width direction. The protrusion has a contact portion extending linearly along the flow path direction and contacting one of the two plate portions. The protrusion is in a wave shape that changes regularly with a period T along the flow path direction when viewed from a plane perpendicular to the flow path direction and the width direction. The shape of the cross section of the protrusion orthogonal to the flow path direction includes a first portion and a second portion, wherein the first portion rises from the other of the two plate portions toward the one of the two plate portions and reaches the contact portion, and the second portion descends from the contact portion toward the other of the two plate portions. When the cross-section in which the shapes of the first part and the second part are linearly symmetrical is called a reference cross-section, in the shape of the cross-section of the protrusion excluding the reference cross-section and the cross-section at a portion that is a period T / 2 away from the reference cross-section, the curvature of the portion of the first part formed by the curve reaching the contact portion is different from the curvature of the portion of the second part formed by the curve extending from the contact portion.

2. The inner fin according to claim 1, Between the position of the reference cross section and the position at a period T / 4 from the reference cross section, The curvature of the portion of the first portion formed by the curve reaching the contact portion increases along the flow path direction, The curvature of a portion of the second portion formed by a curved line extending from the contact portion decreases along the flow path direction.

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

4. The inner fin according to claim 1, A gap is provided between the adjacent protrusions when viewed from the flow path direction.

5. The inner fin according to claim 1, A cross section of the protrusion perpendicular to the flow path direction and the width direction has a wave shape formed by a curved line.

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