Heat exchanger

Abstract

The heat exchanger is provided with: a pipe which has an inner surface facing an inner passage through which exhaust gas discharged from an engine can flow and an outer surface facing an outer passage through which cooling water for heat exchange with the exhaust gas can flow, and which extends in the flow direction of the exhaust gas; and a rib structure provided on the inner surface of the tube and having a plurality of protrusions extending in the extension direction of the tube, the rib structure having a bottom wall surface along the inner surface of the tube at the bottom between two adjacent protrusions among the plurality of protrusions.

Description

Technical Field

[0001] The invention relates to a heat exchanger.

[0002] The present invention claims priority based on Japanese Patent Application No. 2022-140677 filed in Japan on September 5, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] Conventionally, there is known an EGR (Exhaust Gas Recirculation) system which returns a part of exhaust gas exhausted from an engine to intake air to lower the combustion temperature and thereby reduce NOx (nitrogen oxides), which are regulated substances.

[0004] For example, Patent Document 1 discloses an EGR cooler that cools the EGR gas when a part of the exhaust gas from the engine flows into the intake passage as EGR gas (exhaust gas recirculation gas) and refluxes to the engine. The EGR cooler includes a heat exchanger having a water passage through which cooling water flows and a gas passage disposed in the water passage and through which the EGR gas flows.

[0005] However, in recent years, further reduction of NOx has been discussed in environmental regulations. To further reduce NOx, it is necessary to reduce the combustion temperature. Therefore, it is necessary to reduce the oxygen concentration of the intake air, and increasing the amount of EGR gas and reducing the temperature (performance improvement) have become technical issues. For example, in order to improve performance, it is possible to consider changing the size of the heat exchanger (for example, enlarging it).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: (Japanese) Patent Publication No. 2020-84890 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, if the size of the heat exchanger is changed, there is a high possibility that the layout of the peripheral parts such as the pipes connected to the heat exchanger needs to be changed. Therefore, there is room for improvement in terms of improving performance without changing the size.

[0011] Therefore, an object of the present invention is to provide a heat exchanger capable of reducing pressure loss in an internal passage through which exhaust gas flows and improving heat exchange efficiency without changing the size.

[0012] Technical solutions to solve problems

[0013] One aspect of the present invention provides a heat exchanger comprising: a tube having an inner surface facing an internal passage through which exhaust gas discharged from an engine can flow, and an outer surface facing an external passage through which cooling water for heat exchange with the exhaust gas can flow, the tube extending along the flow direction of the exhaust gas; a rib structure provided on the inner surface of the tube, the rib structure having a plurality of protrusions extending along the extension direction of the tube, the rib structure having a bottom portion between two protrusions adjacent to each other among the plurality of protrusions having a bottom wall surface along the inner surface of the tube.

[0014] Effects of the Invention

[0015] According to the above aspect, it is possible to reduce the pressure loss of the internal passage through which the exhaust gas flows and improve the heat exchange efficiency without changing the size. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is an overall configuration diagram of an engine system according to an embodiment.

[0017] Figure 2 This is a cross-sectional view of the EGR cooler according to the embodiment cut along the flow direction of the exhaust gas.

[0018] Figure 3 It is along Figure 2 Cross-sectional view along line III-III.

[0019] Figure 4 It is a perspective view of a part of the heat exchanger according to the embodiment.

[0020] Figure 5 It is a perspective view of the rib structure of the embodiment.

[0021] Figure 6 It is a cross-sectional view of the rib structure according to the embodiment.

[0022] Figure 7 It is a diagram for explaining the function of the rib structure according to the embodiment.

[0023] Figure 8 It is a perspective view of the rib structure of a comparative example.

[0024] Fig. 9 It is a diagram for explaining the function of the rib structure of the comparative example.

[0025] Fig.10 It is a cross-sectional view of a rib structure according to a first modified example of the embodiment.

[0026] Fig.11 It is a cross-sectional view of a rib structure according to a second modified example of the embodiment.

[0027] Fig.12 It is a cross-sectional view of a rib structure according to a third modified example of the embodiment.

[0028] Fig.13 It is a cross-sectional view of the rib structure of the fourth modified example of the embodiment. Specific Embodiment

[0029] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiment, as an example of a heat exchanger, an example of a heat exchanger for an EGR cooler that cools EGR gas when a part of the exhaust gas discharged from the engine is returned to the engine as EGR gas will be described.

[0030] <Engine System>

[0031] Figure 1 It is an overall structure diagram of the engine system 1 of the embodiment.

[0032] For example, the engine system 1 is mounted on construction machinery, transport vehicles, various industrial machinery, etc. The engine system 1 includes an engine 2 and an EGR cooler 3.

[0033] Not shown in the figure, the engine 2 includes a piston, a crankshaft, etc. The intake gas (for example, a combustible mixture containing air and fuel) is introduced into the engine 2 through the intake passage 5. The combustible mixture introduced into the engine 2 explodes / burns by the ignition action of the ignition device. The burned gas is discharged as exhaust gas through the exhaust passage 6. At this time, the piston moves up and down, and the crankshaft rotates. Thus, the engine 2 obtains power.

[0034] <EGR Cooler>

[0035] The EGR cooler 3 is provided in the EGR passage 7 (shown by a dotted line in the figure). The EGR cooler 3 cools the EGR gas (a part of the exhaust gas) flowing through the EGR passage 7. The inlet of the EGR passage 7 is connected to the exhaust passage 6. The outlet of the EGR passage 7 is connected to the intake passage 5.

[0036] A part of the exhaust gas discharged from the engine 2 is introduced into the EGR cooler 3 as EGR gas through the inlet of the EGR passage 7. The EGR gas cooled by the EGR cooler 3 is introduced into the intake passage 5 through the outlet of the EGR passage 7. Thus, a part of the exhaust gas discharged from the engine 2 is returned to the engine 2 as EGR gas.

[0037] Figure 2 It is a cross-sectional view of the EGR cooler 3 of the embodiment cut along the flow direction of the exhaust gas (EGR gas). Figure 3 It is along Figure 2In the following description, the upstream side in the exhaust gas flow direction is referred to as the "front side", and the downstream side in the exhaust gas flow direction is referred to as the "rear side". In addition, left and right are referred to as left and right when viewed from the front side.

[0038] The EGR cooler 3 includes a cylindrical housing 10 , a heat exchanger 20 accommodated in the housing 10 , an inlet-side tank 30 joined to the front side of the housing 10 , and an outlet-side tank 40 joined to the rear side of the housing 10 .

[0039] The shell 10 includes a trunk portion 11 constituting the front and rear central portions of the shell 10, a front bulging portion 12 bulging on the front end side of the shell 10 in a manner larger in diameter than the trunk portion 11, a front opening end portion 13 forming the front end opening of the shell 10, a rear bulging portion 14 bulging on the rear end side of the shell 10 in a manner larger in diameter than the trunk portion 11, and a rear opening end portion 15 forming the rear end opening of the shell 10.

[0040] An inlet 16 for allowing cooling water to flow into the interior of the housing 10 is formed at a lower portion of the front bulged portion 12 .

[0041] An outlet 17 is formed at the upper portion of the rear bulge 14 to allow the cooling water flowing into the housing 10 to flow out. It should be noted that an exhaust hole 18 for exhausting the gas inside the housing 10 may also be formed at the upper portion of the front bulge 12. Figure 2 Although one exhaust hole 18 is shown in the figure, the number is not limited and can be changed according to the design specifications.

[0042] The housing 10 has a first housing 10A and a second housing 10B that are split in the vertical direction. For example, the first housing 10A and the second housing 10B are joined by mutual welding or the like. It should be noted that the housing 10 may also have a split structure in the left-right direction. For example, the form of the split structure of the housing 10 may be changed according to design specifications.

[0043] The heat exchanger 20 includes a plurality of tubes 21 extending in the flow direction of the exhaust gas, a front tube header box plate 22 joined to the front end of each tube 21, and a rear tube header box plate 23 joined to the rear end of each tube 21. When viewed from the front, the tube 21 has a flat shape extending in the vertical direction. When viewed from the front, the plurality of tubes 21 (in the middle) are connected to the front end of each tube 21. Figure 3 9) tubes 21 are arranged left and right. It should be noted that the number of tubes 21 is not limited and can be changed according to design specifications.

[0044] When viewed from the front, the interval t1 between the upper end and the lower end of the tube 21 is defined as the "up-down length t1 of the tube 21", and the interval t2 between the left and right sides of the tube 21 is defined as the "left-right width t2 of the tube 21". For example, the up-down length t1 of the tube 21 is greater than 50 mm and less than 150 mm. For example, the left-right width t2 of the tube 21 is greater than 5 mm and less than 15 mm. It should be noted that the up-down length t1 of the tube 21 and the left-right width t2 of the tube 21 are not limited to the above, and can be changed according to design specifications.

[0045] For example, a portion of the mutually opposing surfaces of each tube 21 is brazed to each other at a dot-shaped protruding portion. For example, the front header box plate 22 is brazed to the front end of each tube 21. For example, the rear header box plate 23 is brazed to the rear end of each tube 21.

[0046] When viewed from the front, the gap between the surfaces of each tube 21 arranged left and right becomes a cooling water flow path 27A (a part of the external passage 27) through which cooling water passes. It is preferable that all cooling water flow paths 27A are set to the same width. In this embodiment, the tubes 21 are arranged left and right, and the inlet 16 for cooling water is formed at the lower part of the front bulge 12. Therefore, the cooling water from the inlet 16 immediately enters the cooling water flow path 27A.

[0047] The cooling water inlet 16 is preferably formed at the left and right center of the lower portion of the front bulge 12. Thus, the cooling water flowing from the inlet 16 flows in the same direction as the vertical direction of each tube 21, thereby preventing the cooling water from being blocked.

[0048] A front cylindrical portion 22A is formed along the inner periphery of the front opening end 13 of the housing 10 on the outer periphery of the front header box panel 22. The front end of the front cylindrical portion 22A is arranged on the front side of the front opening end 13 of the housing 10.

[0049] A rear cylindrical portion 23A is formed along the inner periphery of the rear opening end 15 of the housing 10 on the outer periphery of the rear header box panel 23. The rear end of the rear cylindrical portion 23A is arranged on the rear side of the rear opening end 15 of the housing 10.

[0050] The inlet side tank 30 is joined to the front end of the housing 10 via the front header box plate 22. The inlet side tank 30 includes a front peripheral wall portion 31 extending in a diameter-expanding manner from an exhaust gas inlet 30A serving as an inlet for exhaust gas to the rear side, and a front opening wall portion 32 formed at the rear end side of the front peripheral wall portion 31 and along the inner periphery of the front cylindrical portion 22A.

[0051] The outlet side tank 40 is joined to the rear end of the housing 10 via the rear header box plate 23. The outlet side tank 40 includes a rear peripheral wall portion 41 extending forwardly from an exhaust gas outlet 40A serving as an exhaust gas outflow outlet, and a rear opening wall portion 42 formed at the front end side of the rear peripheral wall portion 41 and along the inner periphery of the rear cylindrical portion 23A.

[0052] For example, the EGR cooler 3 is preferably assembled in the following steps.

[0053] First, the tubes 21 are brazed together. Then, the tube header boxes 22 and 23 are brazed on the brazed structure (joined body of the plurality of tubes 21). In this way, the heat exchanger 20 is manufactured in advance.

[0054] Then, the heat exchanger 20 is housed inside the housing 10 composed of the split housings 10A and 10B. Then, the housings 10A and 10B are joined to each other by welding or the like. Then, the tanks 30 and 40 are joined to each end of the housing 10 via the header boxes 22 and 23 by welding or the like. At this time, the cylindrical portions 22A and 23A of the header boxes 22 and 23 are embedded inside the opening ends 13 and 15 of the housing 10. In addition, the opening wall portions 32 and 42 of the tanks 30 and 40 are embedded further inside these cylindrical portions 22A and 23A. In this state, they are joined together by welding.

[0055] <Heat exchanger>

[0056] Figure 4 It is a perspective view of a part of the heat exchanger 20 according to the embodiment. Figure 5 It is a perspective view of the rib structure 50 according to the embodiment.

[0057] The heat exchanger 20 includes tubes 21, header boxes 22 and 23 (the front header box 22 is shown in the figure), fins 25, and a rib structure 50. Figure 4 FIG. 2 shows the peripheral structure of one of the plurality of tubes 21. Figure 4 The rib structure 50 is omitted in the figure.

[0058] The pipe 21 has an inner surface 21A facing an inner passage 26 through which the exhaust gas discharged from the engine 2 can flow, and an outer surface 21B facing an outer passage 27 through which cooling water for heat exchange with the exhaust gas can flow. The pipe 21 extends along the flow direction of the exhaust gas. Hereinafter, the direction Vt in which the pipe 21 extends along the flow direction of the exhaust gas is referred to as the "extension direction Vt of the pipe 21".

[0059] The length t3 of the tube 21 in the extending direction Vt (the distance between the front end and the rear end of the tube 21) is defined as the “extension length t3 of the tube 21” (see Figure 2For example, the extension length t3 of the tube 21 is greater than or equal to 200 mm and less than or equal to 400 mm. It should be noted that the extension length t3 of the tube 21 is not limited to the above and can be changed according to design specifications.

[0060] The fin 25 is provided in the internal passage 26 of the tube 21. The fin 25 extends along the extension direction Vt of the tube 21. The fin 25 is formed into a plate shape having a length in the flow direction of the exhaust gas and a thickness in the vertical direction when viewed from the front. When viewed from the front, a plurality of fins 25 are arranged at intervals in the vertical direction. Figure 4 2 shows two fins 25 that face each other in the up-down direction among the plurality of fins 25 .

[0061] <Rib structure>

[0062] The rib structure 50 is provided on the inner surface 21A and the outer surface 21B of the tube 21 and the surface of the fin 25 (for example Figure 4 The upper and lower surfaces of the fin 25 shown in FIG. Figure 5 As shown, the rib structure 50 has a plurality of protrusions 60 extending along the extension direction Vt of the tube 21. For example, the rib structure 50 can be processed by etching, sputtering, punching, or vacuum laminating a thin plate (e.g., a plate having a thickness of about 50 μm) on a plate.

[0063] Figure 6 It is a cross-sectional view of the rib structure 50 according to the embodiment. Figure 6 This is a cross-sectional view perpendicular to the extension direction Vt of the tube 21. Figure 6 In the cross-sectional view of FIG. 2 , a portion of the portion where the rib structure 50 is provided in the heat exchanger 20 (for example, a portion on the inner surface 21A side of the tube 21 ) is shown enlarged.

[0064] The rib structure 50 is located at the bottom (at the bottom) between two adjacent protrusions 60 among the plurality of protrusions 60. Figure 6 The lower part in the middle) has a bottom wall surface 51 along the inner surface 21A of the tube 21.

[0065] The convex portion 60 is continuous with the same size throughout the extending direction Vt of the tube 21. For example, the size (cross-sectional area) of the convex portion 60 is the same at any cross-sectional position perpendicular to the extending direction Vt of the tube 21.

[0066] The rib structure 50 has an opening 70 between two adjacent protrusions 60 among the plurality of protrusions 60. The opening 70 is a groove that is continuous with the same size throughout the extension direction Vt of the tube 21. For example, the size (opening area) of the opening 70 is the same at any cross-sectional position orthogonal to the extension direction Vt of the tube 21.

[0067] The rib structure 50 has a first side wall surface 61 and a second side wall surface 62 that are opposite to each other in two protrusions 60. Figure 6 When viewed in cross section, the bottom wall surface 51, the first side wall surface 61, and the second side wall surface 62 have shapes along three sides of a rectangle (an example of a quadrilateral).

[0068] exist Figure 6 In a cross-sectional view, the first side wall surface 61 and the second side wall surface 62 extend vertically from the bottom wall surface 51. Figure 6 When viewed in cross section, the first side wall surface 61 and the second side wall surface 62 are parallel to each other. Figure 6 In a cross-sectional view, the first side wall surface 61 and the second side wall surface 62 extend from the bottom wall surface 51 to the same height position.

[0069] exist Figure 6 When viewed in cross section, the rib structure 50 further includes an end portion ( Figure 6 The upper end of the inclined wall 63, 64 extends obliquely. Figure 6 When observed in cross section, the inclined wall surfaces 63 and 64 gradually separate from each other as they move upward from the upper ends of the side wall surfaces 61 and 62. Hereinafter, the inclined wall surface 63 extending obliquely from the end portion of the first side wall surface 61 on the side opposite to the bottom wall surface 51 is referred to as the "first inclined wall surface 63", and the inclined wall surface 64 extending obliquely from the end portion of the second side wall surface 62 on the side opposite to the bottom wall surface 51 is referred to as the "second inclined wall surface 64".

[0070] exist Figure 6 When observing the cross section of the convex portion 60, the first inclined wall surface 63 and the second inclined wall surface 64 have a shape along the two oblique sides of the triangle. Figure 6 When observed in cross section, one convex portion 60 has a shape that is a combination of a rectangle (the shape of the lower portion of the convex portion in the figure) and a triangle (the shape of the upper portion of the convex portion in the figure).

[0071] exist Figure 6 When observing in cross-section, the interval w1 between the first side wall surface 61 and the second side wall surface 62 in the interval between the two protrusions 60 (the width of the opening portion 70) is set to the "minimum opening width w1", the interval w2 between the upper end of the first inclined wall surface 63 (the upper end of one protrusion 60) and the upper end of the second inclined wall surface 64 (the upper end of the other protrusion 60) is set to the "maximum opening width w2", the interval h1 between the upper ends of the side wall surfaces 61, 62 and the bottom wall surface 51 is set to the "side wall surface height h1", and the interval h2 between the upper end of the protrusion 60 and the bottom wall surface 51 (the maximum upper and lower heights of the protrusion 60) is set to the "maximum height h2".

[0072] For example, the minimum opening width w1 and the side wall height h1 are 1 to 10H .

[0073] H refers to the Kolmogorov scale, and is represented by the following equation (1).

[0074] [Mathematical formula 1]

[0075]

[0076] In the above formula (1), R represents the Reynolds number, and L represents the characteristic length. The characteristic length L is the distance between two fins 25 facing each other in the vertical direction among the plurality of fins 25 (see Figure 4 ).exist Figure 4 In the figure, the characteristic length L is the distance between the lower surface of the upper fin 25 and the upper surface of the lower fin 25 of the two fins 25 .

[0077] For example, the maximum value of the Kolmogorov scale H is about 4.3 μm at the engine rated point of the EGR cooler 3 (the rated point with the most high-temperature EGR gas). For example, the minimum opening width w1 is greater than 1 μm and less than 50 μm. For example, the side wall height h1 is greater than 1 μm and less than 50 μm. For example, the minimum opening width w1 and the side wall height h1 are the same size as each other. It should be noted that the minimum opening width w1 and the side wall height h1 can be different sizes and can also be changed according to design specifications.

[0078] For example, the maximum opening width w2 and the maximum height h2 are 10 to 30 H .

[0079] For example, the maximum opening width w2 is greater than 10 μm and less than 750 μm. For example, the maximum height h2 is greater than 10 μm and less than 750 μm. For example, the maximum opening width w2 and the maximum height h2 are the same size. It should be noted that the maximum opening width w2 and the maximum height h2 can be different sizes and can also be changed according to design specifications.

[0080] <Rib structure function>

[0081] Figure 7 It is a diagram for explaining the function of the rib structure 50 according to the embodiment. Figure 7 Equivalent to Figure 6 The opening between the two protrusions 60 is enlarged. In the figure, reference numeral 80 indicates a vortex tube generated in turbulent flow.

[0082] In the present embodiment, the rib structure 50 has a bottom wall surface 51 along the inner surface 21A of the tube 21. Therefore, the scroll 80 is arranged along the longitudinal direction ( Figure 7 ) grows above.

[0083] In this embodiment, when viewed in a cross-section perpendicular to the extension direction Vt of the tube 21, the bottom wall surface 51, the first side wall surface 61, and the second side wall surface 62 have a shape along the three sides of the rectangle. Figure 7 In this embodiment, the growth direction of the vortex tube 80 is limited by the bottom wall surface 51, the first side wall surface 61 and the second side wall surface 62. For example, the growth direction of the vortex tube 80 is only Figure 7 above.

[0084] Figure 8 It is a perspective view of a rib structure 50X of a comparative example. Fig. 9 It is a diagram for explaining the operation of the rib structure 50X of the comparative example.

[0085] In the comparative example, the scroll 80 has a V-shaped (inverted triangle) opening 70X when viewed in a cross-section perpendicular to the extension direction Vt of the tube 21. Fig. 9 It should be noted that in Fig. 9 In the figure, the angle Ax of the V-shape is about 60 degrees.

[0086] In contrast, in this embodiment, since the growth direction of the vortex tube 80 is only Figure 7 , so the growth direction of the vortex tube 80 is more restricted than that of the comparative example. Therefore, in the present embodiment, energy cascade is less likely to occur than in the comparative example. Energy cascade refers to the process of converting the energy of the vortex into heat by causing a large vortex in the turbulent flow to generate a small vortex. The small vortices generated in the turbulent flow are converted into heat and disappear due to the effect of viscosity. Therefore, as long as the process of large vortices generating small vortices is hindered, energy loss can be suppressed.

[0087] For example, the vortex tube 80 in the turbulent flow grows in the longitudinal direction and shrinks in radius. For example, the vortex tube 80 becomes slender in the longitudinal direction as it grows. For example, if the growth of the vortex tube 80 is saturated, the vortex tube (not shown) whose scale is smaller than the vortex tube 80 with saturated growth is re-grown in a direction (lateral direction) orthogonal to the growth direction of the vortex tube 80. This process of re-growing the vortex tube is one of the causes of the energy cascade.

[0088] In the present embodiment, when viewed in a cross-section perpendicular to the extension direction Vt of the tube 21, the first side wall surface 61 and the second side wall surface 62 extend vertically from the bottom wall surface 51. Therefore, the first side wall surface 61 and the second side wall surface 62 can prevent a new vortex tube from being generated in a direction perpendicular to the growth direction of the vortex tube 80. Thus, energy cascade can be prevented.

[0089] <Effects>

[0090] As described above, the heat exchanger 20 of the present embodiment includes: a tube 21 having an inner surface 21A facing the inner passage 26 through which the exhaust gas discharged from the engine 2 can flow, and an outer surface 21B facing the outer passage 27 through which the cooling water for heat exchange with the exhaust gas can flow, and extending along the flow direction of the exhaust gas; and a rib structure 50 provided on the inner surface 21A of the tube 21 and having a plurality of protrusions 60 extending along the extension direction Vt of the tube 21. The rib structure 50 has a bottom wall surface 51 along the inner surface 21A of the tube 21 at the bottom between two protrusions 60 adjacent to each other among the plurality of protrusions 60.

[0091] According to this structure, since the bottom wall surface 51 is provided along the inner surface 21A of the tube 21, the scroll 80 is arranged along the longitudinal direction ( Figure 7 Therefore, Fig. 9 Compared with the comparative example, the growth direction of the vortex tube 80 is limited. As a result, the energy cascade can be hindered and the pressure loss of the internal passage 26 can be reduced. In addition, the surface area of ​​the portion facing the internal passage 26 is increased through the rib structure 50 of the inner surface 21A of the tube 21, so that the heat exchange efficiency can be improved. In addition, there is no need to change (for example, enlarge) the size of the heat exchanger 20. Therefore, the pressure loss of the internal passage 26 through which the exhaust gas flows can be reduced and the heat exchange efficiency can be improved without changing the size.

[0092] In this embodiment, the rib structure 50 has first and second side wall surfaces 61 and 62 facing each other in two protrusions 60. In a cross-sectional view perpendicular to the extension direction Vt of the tube 21, the bottom wall surface 51, the first and second side wall surfaces 61 and 62 have shapes along three sides of a rectangle.

[0093] According to this structure, Fig. 9 Compared with the V-shaped (comparative example), the growth direction of the scroll 80 is limited. As a result, the energy cascade can be effectively blocked. Therefore, the pressure loss of the internal passage 26 can be effectively reduced.

[0094] In the present embodiment, the first side wall surface 61 and the second side wall surface 62 extend perpendicularly from the bottom wall surface 51 in a cross-sectional view perpendicular to the extending direction Vt of the tube 21 .

[0095] According to this structure, the scroll 80 does not extend in the lateral direction ( Figure 7 Therefore, the vortex tube 80 grows only in the longitudinal direction ( Figure 7 Thus, the energy cascade can be effectively blocked. Therefore, the pressure loss of the internal passage 26 can be effectively reduced.

[0096] In the present embodiment, the rib structure 50 further includes inclined wall surfaces 63 and 64 extending obliquely from ends of the first side wall surface 61 and the second side wall surface 62 on the opposite side to the bottom wall surface 51 in a cross-sectional view perpendicular to the extending direction Vt of the tube 21 .

[0097] According to this structure, the surface area of ​​the portion facing the internal passage 26 is further increased by the inclined wall surfaces 63 and 64 of the rib structure 50. Therefore, the heat exchange efficiency can be further improved.

[0098] In the present embodiment, the fin 25 is further provided, which is provided in the internal passage 26 and extends along the extending direction Vt of the tube 21 . The rib structure 50 is provided on the surface of the fin 25 .

[0099] According to this structure, the surface area of ​​the portion facing the internal passage 26 is further increased by the rib structure 50 on the surface of the fin 25. Therefore, the heat exchange efficiency can be further improved.

[0100] In the present embodiment, the rib structure 50 is provided on the outer surface 21B of the tube 21 .

[0101] According to this structure, the surface area of ​​the portion facing the external passage 27 is further increased by the rib structure 50 of the outer surface 21B of the tube 21. Therefore, the heat exchange efficiency can be further improved. In addition, the pressure loss of the external passage 27 through which the cooling water flows can be reduced.

[0102] In the present embodiment, the heat exchanger 20 is a heat exchanger 20 for the EGR cooler 3 that cools the EGR gas when a part of the exhaust gas is refluxed to the engine 2 as the EGR gas.

[0103] According to this configuration, in the heat exchanger 20 for the EGR cooler 3 , it is possible to reduce the pressure loss in the internal passage 26 through which the exhaust gas flows and improve the heat exchange efficiency without changing the size.

[0104] In the present embodiment, the minimum opening width w1 is greater than or equal to 1 μm and less than or equal to 50 μm.

[0105] According to this structure, it is possible to suppress the vortex layer having a diameter exceeding 50 μm from entering the opening 70 ( Figure 6 The lower part of the opening 70). Therefore, the growth of the vortex layer carried by the vortex tube 80 in the opening 70 can be prevented. Thus, the energy cascade can be effectively prevented. Therefore, the pressure loss of the internal passage 26 can be effectively reduced.

[0106] <First Modification>

[0107] In the embodiment, an example is given in which one protrusion 60 has a shape formed by combining a rectangle and a triangle when the rib structure 50 is viewed in cross section (see FIG. Figure 6 ) is described. In the first variant, Fig.10 As shown, the present invention is different from the embodiment in that one convex portion 160 has a shape formed by combining a rectangle and a trapezoid. In the following description, the same reference numerals are given to the same configurations as those in the embodiment, and the description thereof is omitted.

[0108] Fig.10 FIG. 1 is a cross-sectional view of a rib structure 150 according to a first modified example of the embodiment. Fig.10 In the cross-sectional view of FIG. 1 , a portion of the portion where the rib structure 150 is provided in the heat exchanger 20 (for example, a portion on the inner surface 21A side of the tube 21 ) is shown enlarged.

[0109] exist Fig.10 In a cross-sectional view, the rib structure 150 further includes an upper wall surface 165 extending from the upper ends of the first inclined wall surface 163 and the second inclined wall surface 164 in the left-right direction. Fig.10 In a cross-sectional view, the upper wall surface 165 extends from the end portion of the first inclined wall surface 163 and the second inclined wall surface 164 on the opposite side to the bottom wall surface 51 in parallel with the bottom wall surface 51 .

[0110] exist Fig.10 When observing the cross section of the convex portion 160, the upper wall surface 165, the first inclined wall surface 163 and the second inclined wall surface 164 have shapes along the three sides of the trapezoid. Fig.10 When viewed in cross section, one protrusion 160 has a shape that is a combination of a rectangle and a trapezoid.

[0111] In the first modification, the rib structure 150 further includes an upper wall surface 165 extending parallel to the bottom wall surface 151 from ends of the first inclined wall surface 163 and the second inclined wall surface 164 on the opposite side to the bottom wall surface 51 when viewed in a cross section perpendicular to the extension direction Vt of the tube 21 .

[0112] According to this structure, the surface area of ​​the portion facing the internal passage 26 is further increased by the upper wall surface 165 of the rib structure 150. Therefore, the heat exchange efficiency can be further improved.

[0113] <Second Modification>

[0114] In the second variant, if Fig.11 As shown, the one convex part 260 is different from the embodiment in that it has a shape formed by combining a rectangle and a semicircle. In the following description, the same reference numerals are attached to the same configuration as the embodiment, and the description thereof is omitted.

[0115] Fig.11 FIG. 2 is a cross-sectional view of a rib structure 250 according to a second modified example of the embodiment. Fig.11 In the cross-sectional view of FIG. 2 , a portion of the portion where the rib structure 250 is provided in the heat exchanger 20 (for example, a portion on the inner surface 21A side of the tube 21 ) is shown enlarged.

[0116] exist Fig.11 In a cross-sectional view, the rib structure 250 further includes a curved wall surface 266 extending in a curved manner from the upper ends of the first side wall surface 61 and the second side wall surface 62. Fig.11 In a cross-sectional view, the curved wall surface 266 curves upward from the end of the first side wall surface 61 and the second side wall surface 62 on the side opposite to the bottom wall surface 51. Fig.11 When observing the cross-section, if one convex portion 260 is focused on, it has a shape that is a combination of a rectangle and a semicircle.

[0117] In the second modification, the rib structure 250 further includes a curved wall surface 266 extending in a curved manner from the ends of the first side wall surface 61 and the second side wall surface 62 on the opposite side to the bottom wall surface 51 in a cross-sectional view perpendicular to the extending direction Vt of the tube 21 .

[0118] According to this structure, the surface area of ​​the portion facing the internal passage 26 is further increased by the curved wall surface 266 of the rib structure 250. Therefore, the heat exchange efficiency can be further improved.

[0119] <Third Modification>

[0120] In the third variation, if Fig.12 As shown in FIG. 1 , the present invention is different from the embodiment in that one convex portion 360 has a trapezoidal shape. In the following description, the same reference numerals are given to the same configurations as those in the embodiment, and the description thereof is omitted.

[0121] Fig.12 FIG. 3 is a cross-sectional view of a rib structure 350 according to a third modified example of the embodiment. Fig.12 In the cross-sectional view, a portion of the portion where the rib structure 350 is provided in the heat exchanger 20 (for example, a portion on the inner surface 21A side of the tube 21) is enlarged and shown.

[0122] exist Fig.12 In a cross-sectional view, the rib structure 350 further includes an upper wall surface 365 extending from the upper ends of the first side wall surface 361 and the second side wall surface 362 in the left-right direction. Fig.12 In a cross-sectional view, the upper wall surface 365 extends parallel to the bottom wall surface 51 from the end of the first side wall surface 361 and the second side wall surface 362 on the side opposite to the bottom wall surface 51. Fig.12 When viewed in cross section, the first side wall surface 361 and the second side wall surface 362 are inclined relative to the bottom wall surface 51. Fig.12 When observing the cross section of the convex portion 360, the side wall surfaces 361 and 362 gradually approach each other as they move upward from the bottom wall surface 51. Fig.12 In a cross-sectional view, the bottom wall surface 51, the first side wall surface 361, and the second side wall surface 362 have a shape along the three sides of the trapezoid. Fig.12 When observing the cross section, if one convex portion 60 is focused on, it has an isosceles trapezoidal shape.

[0123] In the third modification, the rib structure 350 further includes an upper wall surface 365 extending in the left-right direction from the upper ends of the first side wall surface 361 and the second side wall surface 362 when viewed in a cross-section perpendicular to the extension direction Vt of the tube 21. When viewed in a cross-section perpendicular to the extension direction Vt of the tube 21, the first side wall surface 361 and the second side wall surface 362 are inclined relative to the bottom wall surface 51.

[0124] According to this structure, the surface area of ​​the portion facing the internal passage 26 is further increased by the upper wall surface 365 of the rib structure 350 and the side wall surfaces 361 and 362 inclined relative to the bottom wall surface 51. Therefore, the heat exchange efficiency can be further improved.

[0125] <Fourth Modification>

[0126] In the fourth variation, if Fig.13 As shown, the present invention is different from the embodiment in that one convex portion 460 has an inverted trapezoidal shape. In the following description, the same reference numerals are given to the same configurations as those in the embodiment, and the description thereof is omitted.

[0127] Fig.13 FIG. 4 is a cross-sectional view of a rib structure 450 according to a fourth modified example of the embodiment. Fig.13 In the cross-sectional view, a portion of the portion where the rib structure 450 is provided in the heat exchanger 20 (for example, a portion on the inner surface 21A side of the tube 21) is enlarged and shown.

[0128] exist Fig.13 In a cross-sectional view, the rib structure 450 further includes an upper wall surface 465 extending from the upper ends of the first side wall surface 461 and the second side wall surface 462 in the left-right direction. Fig.13 In a cross-sectional view, the upper wall surface 465 extends parallel to the bottom wall surface 51 from the end of the first side wall surface 461 and the second side wall surface 462 on the side opposite to the bottom wall surface 51. Fig.13 When viewed in cross section, the first side wall surface 461 and the second side wall surface 462 are inclined relative to the bottom wall surface 51. Fig.13 When observing the cross section of the convex portion 460, if one side wall surface 461 and 462 is focused on, the side wall surfaces 461 and 462 gradually separate from each other as they move upward from the bottom wall surface 51. Fig.13In a cross-sectional view, the bottom wall surface 51, the first side wall surface 461, and the second side wall surface 462 have a shape along the three sides of the trapezoid. Fig.13 When observing the cross-section, if one convex portion 460 is focused on, it has a shape in which an isosceles trapezoid is reversed up and down.

[0129] In the fourth modification, the rib structure 450 further includes an upper wall surface 465 extending in the left-right direction from the upper ends of the first side wall surface 461 and the second side wall surface 462 when viewed in a cross-section perpendicular to the extension direction Vt of the tube 21. When viewed in a cross-section perpendicular to the extension direction Vt of the tube 21, the first side wall surface 461 and the second side wall surface 462 are inclined relative to the bottom wall surface 51.

[0130] According to this structure, the surface area of ​​the portion facing the internal passage 26 is further increased by the upper wall surface 465 of the rib structure 450 and the side wall surfaces 461 and 462 inclined relative to the bottom wall surface 51. Therefore, the heat exchange efficiency can be further improved.

[0131] <Other Implementation Methods>

[0132] In the above-mentioned embodiment, an example is given in which the heat exchanger is further provided with fins which are arranged in the internal passage and extend along the extension direction of the tube, but the invention is not limited thereto. For example, the heat exchanger may not have fins. For example, the heat exchanger may have a tube and a rib structure, wherein the tube has an inner surface facing the internal passage through which the exhaust gas discharged from the engine can flow, and an outer surface facing the external passage through which the cooling water for heat exchange with the exhaust gas can flow, and extends along the flow direction of the exhaust gas, and the rib structure is arranged on the inner surface of the tube and has a plurality of protrusions extending along the extension direction of the tube. For example, the structural form of the heat exchanger can be changed according to the design specifications.

[0133] In the above-mentioned embodiment, the example of the rib structure being provided on the surface of the fin is cited for explanation, but the invention is not limited thereto. For example, the rib structure may be provided on one side of the fin (for example, either the upper surface or the lower surface). For example, the rib structure may not be provided on the surface of the fin. For example, the rib structure may be provided on the inner surface of the tube. For example, the arrangement form of the rib structure may be changed according to the design specifications.

[0134] In the above-mentioned embodiment, the example in which the rib structure is provided on the outer surface of the tube is cited for explanation, but the invention is not limited thereto. For example, the rib structure may not be provided on the outer surface of the tube. For example, the rib structure may be provided on the inner surface of the tube. For example, the arrangement form of the rib structure may be changed according to the design specifications.

[0135] In the above-mentioned embodiment, the example in which the tube has a flat shape is cited for explanation, but the invention is not limited thereto. For example, the tube may have a circular cross section (ring shape). For example, the shape of the tube may be changed according to design specifications.

[0136] As described above, the embodiments of the present invention are described, but the present invention is not limited thereto, and additions, omissions, substitutions, and other changes to the structure may be made without departing from the gist of the present invention, and the above-mentioned embodiments may be appropriately combined.

[0137] (Note 1)

[0138] A heat exchanger comprising:

[0139] a pipe having an inner surface facing an inner passage through which exhaust gas discharged from the engine can flow, and an outer surface facing an outer passage through which cooling water for heat exchange with the exhaust gas can flow, and extending along a flow direction of the exhaust gas;

[0140] a rib structure, which is arranged on the inner surface of the tube and has a plurality of convex portions extending along the extending direction of the tube,

[0141] The rib structure has a bottom wall surface along the inner surface of the tube at a bottom portion between two adjacent protrusions among the plurality of protrusions.

[0142] (Note 2)

[0143] The heat exchanger according to Supplement 1, wherein:

[0144] The rib structure has a first side wall surface and a second side wall surface that are opposite to each other in the two protrusions.

[0145] The bottom wall surface, the first side wall surface, and the second side wall surface have shapes along three sides of a quadrilateral when viewed in a cross section perpendicular to the extending direction of the tube.

[0146] (Note 3)

[0147] The heat exchanger according to Supplement 2, wherein:

[0148] The first side wall surface and the second side wall surface extend perpendicularly from the bottom wall surface when viewed in a cross section perpendicular to the extending direction of the tube.

[0149] (Note 4)

[0150] The heat exchanger according to Supplement 2 or 3, wherein:

[0151] The rib structure further includes an inclined wall surface extending obliquely from an end portion of the first side wall surface and the second side wall surface on a side opposite to the bottom wall surface when viewed in a cross section perpendicular to an extending direction of the tube.

[0152] (Note 5)

[0153] The heat exchanger according to any one of Supplementary Notes 1 to 4, wherein

[0154] There is also a fin, which is provided in the internal passage and extends along the extension direction of the tube.

[0155] The rib structure is arranged on the surface of the fin.

[0156] (Note 6)

[0157] The heat exchanger according to any one of Supplementary Notes 1 to 5, wherein

[0158] The rib structure is disposed on the outer surface of the tube.

[0159] (Note 7)

[0160] The heat exchanger according to any one of Supplementary Notes 1 to 6, wherein

[0161] The heat exchanger is a heat exchanger for an EGR cooler that cools the EGR gas when a part of the exhaust gas is refluxed to the engine as the EGR gas.

[0162] Description of Reference Numerals

[0163] 2 Engine

[0164] 3 EGR cooler

[0165] 20 Heat exchanger

[0166] 21 tubes

[0167] 21A Inner surface

[0168] 21B Outer surface

[0169] 25 fins

[0170] 26 Internal Passage

[0171] 27 Cooling water passage (external passage)

[0172] 50 Rib structure

[0173] 51 bottom wall

[0174] 60 bulge

[0175] 61 First side wall

[0176] 62 Second side wall

[0177] 63 first inclined wall surface (inclined wall surface)

[0178] 64 second inclined wall surface (inclined wall surface)

[0179] Extension direction of Vt tube

Claims

1. A heat exchanger, characterized in that: have: a pipe having an inner surface facing an inner passage through which exhaust gas discharged from an engine can flow, and an outer surface facing an outer passage through which cooling water for heat exchange with the exhaust gas can flow, the pipe extending along a flow direction of the exhaust gas; a rib structure, which is arranged on the inner surface of the tube and has a plurality of protrusions extending along the extending direction of the tube, The rib structure has a bottom portion between two adjacent convex portions among the plurality of convex portions having a bottom wall surface along the inner surface of the tube.

2. The heat exchanger according to claim 1, characterized in that The rib structure has a first side wall surface and a second side wall surface that are opposite to each other in the two protrusions. The bottom wall surface, the first side wall surface, and the second side wall surface have a shape along three sides of a quadrilateral when viewed in a cross section perpendicular to the extending direction of the tube.

3. The heat exchanger according to claim 2, characterized in that The first side wall surface and the second side wall surface extend perpendicularly from the bottom wall surface when viewed in a cross section perpendicular to the extending direction of the tube.

4. The heat exchanger according to claim 2 or 3, characterized in that: The rib structure further includes an inclined wall surface extending obliquely from an end portion of the first side wall surface and the second side wall surface on a side opposite to the bottom wall surface when viewed in a cross section perpendicular to the extending direction of the tube.

5. The heat exchanger according to claim 1 or 2, characterized in that: There is also a fin, which is provided in the internal passage and extends along the extension direction of the tube, The rib structure is arranged on the surface of the fin.

6. The heat exchanger according to claim 1 or 2, characterized in that: The rib structure is disposed on the outer surface of the tube.

7. The heat exchanger according to claim 1 or 2, characterized in that: The heat exchanger is a heat exchanger for an EGR cooler that cools the EGR gas when a part of the exhaust gas is refluxed to the engine as the EGR gas.

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