CN112368535A

CN112368535A - Heat exchanger

Info

Publication number: CN112368535A
Application number: CN201980045419.XA
Authority: CN
Inventors: 岩崎充; 山中真由美
Original assignee: Marilyn Co ltd
Current assignee: Marilyn Co ltd
Priority date: 2018-07-20
Filing date: 2019-06-05
Publication date: 2021-02-12
Anticipated expiration: 2039-06-05
Also published as: JP6550177B1; CN112368535B; JP2020012621A; WO2020017176A1

Abstract

The heat exchanger (100) comprises: a tube (50) that partitions a first flow path (21) through which a first fluid flows in a flow path direction and a second flow path (22) through which a second fluid flows; and an inner fin (40) disposed in the first flow path (21), the inner fin (40) having: a flat wall (41) in contact with the tube (50); a vertical wall (42) that is connected in the direction of intersection of the flat walls (41) and that divides the first flow path (21) into a plurality of small flow paths (23) arranged in the flow path width direction; and fin portions (43, 44) that are cut and raised from the flat walls (41) and protrude toward the small flow path (23), wherein the tube (50) has opposing grooves (77) that are recessed from a flow path surface (63) facing the first flow path (21) and raised from a flow path surface (62) facing the second flow path (22), extend across the small flow path (23) across the plurality of flat walls (41), and face the flow of the second fluid, and wherein the opposing grooves (77) have: a pair of inclined portions (77a) inclined with respect to the flow path direction; and an intersection part (77b) where the paired inclined parts (77a) intersect with each other.

Description

Heat exchanger

Technical Field

The present invention relates to a heat exchanger for exchanging heat between fluids.

Background

JP2014-169857a discloses an exhaust gas heat exchanger that cools exhaust gas of an internal combustion engine with cooling water.

In the exhaust gas heat exchanger, a pipe (tube) forming an exhaust gas flow path inside the tank is disposed. The tube is provided with inner fins (inner fins) as heat conductive members for promoting heat exchange of the exhaust gas and the cooling fluid. The exhaust gas introduced into the exhaust gas heat exchanger flows through the tubes while contacting the inner fins, and is cooled by radiating heat to the cooling water flowing outside the tubes.

In the above pipe, a plurality of concave grooves (dimples) are formed as convex portions protruding from the outer surface thereof. The grooves are provided as members for reducing the temperature of the temperature boundary layer of the cooling water.

Disclosure of Invention

However, in recent years, there is a tendency that a demand for a heat exchanger with higher performance is increased, and even in the heat exchanger described in JP2014-169857a, there is room for improvement for further higher performance.

The purpose of the present invention is to further improve the heat exchange performance in a heat exchanger.

According to one aspect of the present invention, a heat exchanger for exchanging heat between a first fluid and a second fluid includes: a tube that partitions a first flow path through which a first fluid flows in a flow path direction and a second flow path through which a second fluid flows; and an inner fin disposed in the first flow path, the inner fin having: a flat wall in contact with the tube; a vertical wall connected in the intersecting direction of the flat walls and dividing the first flow path into a plurality of small flow paths arranged in the flow path width direction; and a fin portion that is cut and raised from the flat wall and protrudes toward the small flow path, wherein the tube has an opposing groove that is recessed from a flow path surface facing the first flow path and raised from a flow path surface facing the second flow path, and extends across the small flow path across the plurality of flat walls and faces a flow of the second fluid, and the opposing groove has: a pair of inclined portions inclined with respect to the flow path direction; and an intersection portion where the paired inclined portions intersect with each other.

According to the above aspect, in the heat exchanger, although the contact area between the tube and the inner fin is reduced due to the depression of the groove, the heat transfer from the second fluid to the tube can be promoted by the opposing groove, and the heat transfer from the first fluid to the tube can be promoted by the fin portion. Thereby, the heat exchanger can improve heat exchange performance.

Drawings

Fig. 1 is a perspective view showing a heat exchanger according to an embodiment of the present invention.

Fig. 2 is an exploded perspective view of the heat exchanger.

Fig. 3 is an exploded perspective view of the tube.

Fig. 4 is a perspective view showing a cross section in which a part of the heat exchanger is cut.

Fig. 5 is a perspective view showing a section in which a part of the inner fin is cut.

Fig. 6 is a top view of the inner fin.

Fig. 7 is a graph showing a relationship between the ratio a and the temperature T based on the non-contact area of the groove.

Fig. 8 is a perspective view showing a cross section of a part of a heat exchanger according to a modification.

Detailed Description

Hereinafter, a heat exchanger 100 according to an embodiment of the present invention will be described with reference to the drawings. In the drawings, a part of the heat exchanger 100 is omitted for simplicity of explanation.

The heat exchanger 100 is a water-cooled EGR cooler used in an EGR (Exhaust Gas Recirculation) system (not shown) of a vehicle. The heat exchanger 100 cools a part (first fluid) of the exhaust gas discharged from the engine with cooling water (second fluid). The cooling water circulating through the cooling circuit flows through the heat exchanger 100, and then flows through a radiator (also referred to as a radiator) to dissipate heat to the outside air.

As shown in fig. 1 and 2, the heat exchanger 100 includes: a plurality of tubes (tubes) 50 that form a first flow path 21 in which exhaust gas flows; and a casing 10 forming a second flow path 22 through which cooling water circulates between the stacked tubes 50.

Hereinafter, the structure of the heat exchanger 100 will be described by setting X, Y, Z three axes orthogonal to each other in each drawing. In the tube 50, the X-axis direction in which the first channel 21 extends is referred to as a "channel direction", and the Y-axis direction is referred to as a "channel width direction".

As shown in fig. 2, the tube 50 is assembled from a semi-cylindrical upper plate 60 and a lower plate 80 to form a cylindrical shape that is flat in the Z-axis direction. Inner fin 40 is disposed between upper plate 60 and lower plate 80 as a heat conductive member.

The upper plate 60 and the lower plate 80 may be formed into a flat semi-cylindrical shape by press working a metal plate.

The upper plate 60 has: and a heat conductive plate portion 61 having a plate shape and extending in the X-axis direction and the Y-axis direction. The heat conductive plate portion 61 is formed with, as grooves (ridges) for guiding the flow of the cooling water as described below: one inclined groove 71, one upstream-side inclined groove 72, four longitudinal grooves 73 (linear grooves), and a plurality of opposing grooves 77 (vortex generating grooves).

The lower plate 80 has: and a heat conductive plate portion 81 which is plate-shaped and extends in the X-axis direction and the Y-axis direction. The heat conductive plate portion 81 is formed with: one inclined groove 91, one upstream-side inclined groove 92, and four longitudinal grooves 93 (linear grooves).

The

inclined grooves

71, 91, the upstream-side

inclined grooves

72, 92, and the

longitudinal grooves

73, 93 are opposed to each other in the Z-axis direction and project toward the second flow path 22, respectively, for guiding the flow of the cooling water.

The housing 10 is formed in a cylindrical shape having a substantially rectangular cross section by assembling the semi-cylindrical upper case 20 and the lower case 30. Pipes (pipe)17, 18 are connected to the housing 10.

As shown in fig. 1, a second inlet 25 and a second outlet 27 are provided in the housing 10, the second inlet 25 distributing the cooling water introduced from the duct 17 to the second flow paths 22 between the respective tubes 50, and the second outlet 27 guiding the cooling water flowing out from the second flow path 22 to the duct 18.

Both opening ends of the housing 10 are connected to a pipe (not shown) of the EGR passage via frame-

shaped pipe holders

15 and 16. The stem 15 is provided with a first inlet 35 for distributing the exhaust gas introduced from the pipe of the EGR passage to the first flow path 21. The inside of the stem 16 is provided with a first outlet 36 for guiding the exhaust gas flowing out of the first flow path 21 to the pipe of the EGR passage.

When the heat exchanger 100 is manufactured, an assembly body is formed by assembling the above components. The metal assembly is transported to a heating furnace and heat-treated, and the respective joint portions are joined by brazing.

When the heat exchanger 100 is operated, as indicated by black arrows in fig. 1, the cooling water circulating in the cooling circuit flows from the inside of the duct 17 into the second inlet 25 and is distributed to the second flow paths 22 between the tubes 50. The cooling water flowing through the second flow path 22 is collected at the second outlet 27 and flows out through the inside of the duct 18. On the other hand, as shown by the hollow arrows in fig. 1, the exhaust gas flowing through the EGR passage is distributed to the first flow paths 21 in the respective tubes 50 through the first inlets 35 in the tube holders 15. The exhaust gas flowing through the first flow path 21 is cooled by radiating heat to the cooling water flowing through the second flow path 22 through the respective pipes 50. The exhaust gas flowing out of the first flow path 21 is collected through the first outlet 36 in the stem 16 and supplied to the combustion chamber of the engine.

Next, the structure of the tube 50 will be described with reference to fig. 3 to 6.

Fig. 3 is a perspective view showing the upper plate 60 and the inner fins 40 in a state where the tube 50 is disassembled. The inner fin 40 has a corrugated plate shape with a substantially rectangular cross section. In the tube 50, flat walls 41 extending in the X-axis direction and the Y-axis direction and upright walls 42 connected to the flat walls 41 in the intersecting direction (X-axis direction and Z-axis direction) are alternately arranged. The offset (offset) type inner fins 40 are offset for each region divided by a predetermined length in the X-axis direction so that the positions of the flat wall 41 and the upright wall 42 are displaced by the predetermined length in the Y-axis direction.

Fig. 4 is a perspective view showing a cross section of a part of the heat pipe 50. The first flow path 21 is formed as a flat space between the upper plate 60 and the lower plate 80. The first flow path 21 is divided into a plurality of small flow paths 23 each including a flat wall 41 and a vertical wall 42 of the inner fin 40 by each partition (segment).

Fig. 5 is a perspective view showing a part of the inner fin 40 in an enlarged manner. In the inner fin 40, each partition has an upstream-side fin portion 43 and a downstream-side fin portion 44 that are cut and raised from the flat wall 41. The flat wall 41 is formed with

fin openings

45 and 46 that are opened at the cut and raised portions of the

fin portions

43 and 44. The inner fin 40 may be formed by a press process.

The fin portion 43 on the upstream side is cut and tilted toward the upstream in the exhaust gas flow direction. The fin portion 43 is formed: a trapezoid having a bent side 43a bent from the flat wall 41, an inclined side 43b crossing the small flow path 23, and a long side 43c and a short side 43d connecting the bent side 43a and the inclined side 43 b.

The fin portion 44 on the downstream side is cut and tilted toward the downstream in the exhaust gas flow direction. The fin portion 44 is formed of: a trapezoid having a bent side 44a bent from the flat wall 41, an inclined side 44b crossing the small flow path 23, and a long side 44c and a short side 44d connecting the bent side 44a and the inclined side 44 b.

The bent edge 43a of the upstream fin portion 43 and the bent edge 44a of the downstream fin portion 44 are arranged to be inclined at substantially the same angle with respect to the Y axis and substantially parallel to each other.

The inclined side 43b of the upstream fin portion 43 and the inclined side 44b of the downstream fin portion 44 are arranged to be inclined with respect to the Y axis and to cross the small flow path 23. As described later, the flow of the exhaust gas flowing through the first flow path 21 is blocked by the

inclined sides

43b and 44b of the

fin portions

43 and 44 extending in the direction inclined with respect to the Y axis, and becomes a helical longitudinal vortex that revolves around the X axis.

As shown in fig. 3, the heat conductive plate portion 61 of the upper plate 60 has a plurality of opposing grooves 77 arranged along the longitudinal grooves 73. The interval L between the opposed grooves 77 arranged along the X-axis direction can be arbitrarily set according to the performance required of the heat exchanger 100 as described later.

The V-shaped opposed grooves 77 have: a pair of inclined portions 77a inclined with respect to the Y axis, and an intersecting portion 77b where the pair of inclined portions 77a intersect with each other. In the opposing grooves 77, a pair of inclined portions 77a are inclined so as to spread toward the upstream side in the exhaust gas flow direction, and an intersecting portion 77b protrudes toward the downstream side in the exhaust gas flow direction. As described later, the flow of the cooling water flowing through the second flow path 22 is blocked by the inclined portion 77a of the opposing groove 77 extending in the intersecting direction inclined with respect to the Y axis, and becomes a helical longitudinal vortex that revolves around the X axis.

As shown in fig. 4, the opposite grooves 77 may be formed in the upper plate 60 by press working. The opposed grooves 77 are raised in a bank shape on the flow path surface 62 of the upper plate 60 facing the second flow path 22, and are recessed in a trench shape on the flow path surface 63 of the upper plate 60 facing the first flow path 21. The opposing groove 77 has a groove-like recess 77 c. Similarly, the longitudinal groove 73 may be formed in the upper plate 60 by press working. The longitudinal groove 73 has a groove-like recess 73 c. In addition, the longitudinal groove 93 may be formed in the lower plate 80 by press working. The longitudinal groove 93 has a groove-like depression 93 c.

Fig. 6 is a plan view showing the inner fin 40 in solid lines and the upper plate 60 in two-dot chain lines. In the upper plate 60, portions facing the flat walls 41 of the inner fins 40 through the small flow paths 23 and portions contacting and joined to the flat walls 41 are alternately arranged in the Y-axis direction.

The V-shaped facing groove 77 extends across the small flow path 23 in the Y-axis direction and across the flat walls 41 of the plurality of (four) partitions.

The linear vertical grooves 73 extend across the small flow paths 23 in the X-axis direction and across the flat walls 41 of the plurality of partitions.

As shown in fig. 4, the

fin opening portions

45 and 46 opened after the

fin portions

43 and 44 of the inner fin 40 are cut and raised have portions facing the recesses 93c of the longitudinal grooves 93. The

fin openings

45 and 46 of the inner fin 40 have portions facing the recess 77c of the opposing groove 77 and the recess 73c of the longitudinal groove 73.

Next, the operation of the heat exchanger 100 will be explained.

When the heat exchanger 100 is operated, the exhaust gas flowing through the EGR passage flows through the first flow passage 21 while contacting the inner fins 40 and the tubes 50, and is cooled by radiating heat to the cooling water flowing through the second flow passage 22 via the tubes 50. The inner fins 40 function as heat conductive members that conduct the heat of the exhaust gas to the upper plate 60 and the lower plate 80 of the pipe 50.

The flow of the exhaust gas flowing through the first flow path 21 is blocked in the oblique direction with respect to the X axis by the

fin portions

43 and 44 of the inner fin 40, and a helical longitudinal vortex that revolves around the X axis is generated. Thus, in the region of the first flow path 21 including the boundary layer in the vicinity of the inner wall surface (flow path surface 63) of the pipe 50 and the surface of the inner fin 40, the heat transfer (heat transfer) of the exhaust gas can be promoted by the vortex flow (turbulent flow). The vertical vortex of the exhaust gas generated on the downstream side of the

fin portions

43 and 44 can suppress the flow resistance of the exhaust gas as compared with the horizontal vortex revolving around the Y axis, and the region where the turbulent flow is generated can be increased in the X axis direction.

On the other hand, the flow of the cooling water flowing through the second flow path 22 is blocked in the direction obliquely crossing the X axis by the opposing grooves 77, and a helical longitudinal vortex is generated that revolves around the X axis. Thus, in the region of the second flow path 22 including the boundary layer in the vicinity of the outer wall surface (flow path surface 62) of the pipe 50, the heat transfer of the exhaust gas can be promoted by the vortex flow (turbulent flow).

The longitudinal vortex of the cooling water generated on the downstream side of the opposing grooves 77 can suppress the flow resistance of the cooling water as compared with the lateral vortex rotating around the Y axis, but the region where the turbulent flow is generated is limited to a certain range in the X axis direction. Therefore, in the heat exchanger 100, the heat transfer of the cooling water can be promoted and the heat exchange efficiency can be improved by reducing the interval L between the opposed grooves 77 arranged in the X-axis direction to a certain extent.

However, in heat exchanger 100, when interval L between opposed notches 77 is reduced, the area of recess 77c of opposed notch 77 facing inner fin 40 increases, and therefore the non-contact area between tube 50 and inner fin 40 increases. Therefore, in the heat exchanger 100, if the interval L between the opposing grooves 77 is reduced to a certain extent, the amount of heat transfer of the inner fins 40 decreases, and the heat exchange efficiency decreases.

Fig. 7 shows the following results: that is, the result of the simulation analysis is a value obtained when the temperature difference T of the cooling water caused by the flow through the heat exchanger 100 changes according to the ratio a based on the non-contact area of the concave groove when the cooling water and the exhaust gas are caused to flow through the heat exchanger 100 under the predetermined condition. Further, the temperature difference T of the cooling water is: the difference between the temperature of the cooling water flowing through the second inlet 25 and the temperature of the cooling water flowing through the second outlet 27. The ratio a of the non-contact area based on the groove is: the ratio of the contact area C of the tube 50 and the inner fin 40 in the case where the grooves (the opposed grooves 77, the longitudinal grooves 73, and the longitudinal grooves 93) are provided to the contact area B of the tube 50 and the inner fin 40 in the case where no grooves are provided is expressed by the following equation.

A＝(C/B)×100

As shown in fig. 7, as the ratio a based on the non-contact area of the concave groove is larger from 0%, the temperature difference T of the cooling water gradually becomes higher and becomes a peak, and after the peak, the temperature difference T of the cooling water gradually becomes lower as the ratio a becomes larger. In the range where the ratio a is 2% or more and 14% or less, the temperature difference T becomes a reference value or more required by the market.

In the heat exchanger 100, the pitch L between the opposed grooves 77 arranged in the X-axis direction is set so that the ratio a based on the non-contact area of the grooves is in the range of 2% to 14% based on the result of the above simulation analysis.

Next, the effects of the present embodiment will be explained.

According to the present embodiment, the heat exchanger 100 includes: a pipe 50 that partitions a first flow path 21 through which an exhaust gas (first fluid) flows in an X direction (flow path direction) and a second flow path 22 through which cooling water (second fluid) flows; and an inner fin 40 disposed in the first flow path 21, the inner fin 40 including: a flat wall 41 in contact with the tube 50; a vertical wall 42 connected in the intersecting direction of the flat wall 41 and dividing the first flow path 21 into a plurality of small flow paths 23 arranged in the Y-axis direction (flow path width direction); and fin portions 43 and 44 cut and raised from the flat wall 41 and protruding toward the small flow path 23, the tube 50 having an opposing groove 77 that is recessed from the flow path surface 63 facing the first flow path 21 and raised from the flow path surface 62 facing the second flow path 22, and extends across the small flow path 23 and across the plurality of flat walls 41 and faces the flow of the second fluid, the opposing groove 77 having: a pair of inclined portions 77a inclined with respect to the X-axis direction (flow path direction); and an intersection 77b where the paired inclined portions 77a intersect with each other.

According to the above structure, in the heat exchanger 100, the inner fins 40 and the tubes 50 transfer heat between the exhaust gas and the cooling water, but the contact area between the tubes 50 and the inner fins 40 is reduced due to the provision of the depressions 77c of the opposed grooves 77. On the other hand, however, the cooling water is guided by the opposing grooves 77 to promote heat transfer from the cooling water to the tubes 50. The

fin portions

43, 44 generate a vortex flow in the flow of the exhaust gas, thereby promoting heat transfer from the exhaust gas to the pipe 50. This improves the heat exchange performance of the heat exchanger 100, and enables downsizing and weight reduction.

Further, the cooling water flowing through the second flow path 22 in the X-axis direction passes over the opposed concave grooves 77 disposed so as to cross the second flow path 22, and becomes a vortex flow. Thus, in the heat exchanger 100, the heat transfer from the cooling water to the tubes 50 is promoted by generating a vortex in the flow of the cooling water.

Further, the cooling water flowing through the second flow path 22 passes over the intersection 77b and the inclined portion 77a inclined with respect to the X-axis direction to form a vortex flow. Thus, in the heat exchanger 100, the longitudinal vortex flow is generated in the flow of the cooling water by the opposed grooves 7, thereby reducing the flow resistance of the cooling water and promoting the heat transfer from the cooling water to the tubes 50.

Further, the following configuration may be adopted: the heat exchanger 100 includes: a pipe 50 that partitions a first flow path 21 through which an exhaust gas (first fluid) flows in an X-axis direction (flow path direction) and a second flow path 22 through which cooling water (second fluid) flows; and an inner fin 40 disposed in the first flow path 21, the inner fin 40 including: a flat wall 41 in contact with the tube 50; a vertical wall 42 connected in the intersecting direction of the flat wall 41 and dividing the first flow path 21 into a plurality of small flow paths 23 arranged in the Y-axis direction (flow path width direction); and fin portions 43 and 44 that protrude from the flat wall 41 in a cut-and-raised manner toward the small flow path 23, the tube 50 including: an opposing groove 77 that is recessed from the flow path surface 63 facing the first flow path 21, and that rises from the flow path surface 62 facing the second flow path 22, and that extends across the small flow path 23 and across the plurality of flat walls 41 and faces the flow of the second fluid; and longitudinal grooves 73, 93 recessed from the flow path surface 63 facing the first flow path 21 and raised from the flow path surface 62 facing the second flow path 22, and extending in the X-axis direction (flow path direction), the plurality of opposed grooves 77 being arranged along the longitudinal grooves 73, 93.

fin portions

43, 44 generate a vortex flow in the flow of the exhaust gas, whereby the heat transfer from the exhaust gas to the pipe 50 can be promoted. This improves the heat exchange performance of the heat exchanger 100, and enables downsizing and weight reduction.

Further, the cooling water flowing through the second flow path 22 in the X-axis direction passes over the concave groove 77 disposed so as to cross the second flow path 22, and becomes a vortex. Thus, in the heat exchanger 100, by generating a vortex flow in the flow of the cooling water, the heat transfer from the cooling water to the tubes 50 is promoted.

Further, the cooling water flowing through the second flow path 22 flows along the pair of

vertical grooves

73 and 93 facing each other, and thereby the potential energy flowing in the X-axis direction increases, and a strong vortex is formed each time the cooling water passes over the plurality of facing grooves 77 arranged along the

vertical grooves

73 and 93. Thereby, the heat transfer from the cooling water to the tubes 50 is promoted. Further, the opposed grooves 77 are formed only in one of the pair of tubes 50 stacked on each other, whereby the flow resistance of the cooling water can be suppressed.

Further, the present invention may be configured such that: the heat exchanger 100 includes: a pipe 50 that partitions a first flow path 21 through which an exhaust gas (first fluid) flows in an X-axis direction (flow path direction) and a second flow path 22 through which cooling water (second fluid) flows; and an inner fin 40 disposed in the first flow path 21, the inner fin 40 including: a flat wall 41 in contact with the tube 50; a vertical wall 42 connected in the intersecting direction of the flat wall 41 and dividing the first flow path 21 into a plurality of small flow paths 23 arranged in the Y-axis direction (flow path width direction); and fin portions 43 and 44 cut and raised from the flat wall 41 and protruding toward the small flow paths 23, wherein the tube 50 has opposing grooves 77 and longitudinal recesses 73 and 93 (grooves) that are recessed from the flow path surface 63 facing the first flow path 21 and raised from the flow path surface 62 facing the second flow path 22, and the opposing grooves 77 and the longitudinal recesses 73 and 93 (grooves) are provided in the tube 50, whereby the ratio a of the non-contact area of the tube 50 that is not in contact with the inner fins 40 is set in the range of 2% to 14%.

According to the above configuration, in the heat exchanger 100, the inner fin 40 and the tube 50 transfer heat between the exhaust gas and the cooling water, but the contact area between the tube 50 and the inner fin 40 is reduced by providing the opposed grooves 73 and the

recesses

77c, 73c, 93c of the

longitudinal recesses

73, 93. On the other hand, however, the cooling water is guided by the opposing grooves 77 and the

longitudinal grooves

73 and 93, and heat transfer from the cooling water to the tube 50 is promoted. The

fin portions

Further, the non-contact area between the tube 50 and the inner fin 40 can be suppressed by the

depressions

77c, 73c, 93c of the opposing groove 77 and the

longitudinal grooves

73, 93, and the effect of promoting the heat transfer from the cooling water to the tube 50 by the flow (vortex) of the cooling water guided to the opposing groove 77 and the

longitudinal grooves

73, 93 can be sufficiently obtained. Thereby, the heat exchanger 100 can obtain heat exchange performance required by the market.

Further, according to the present embodiment, the heat exchanger 100 includes: a pipe 50 that partitions a first flow path 21 through which an exhaust gas (first fluid) flows in an X-axis direction (flow path direction) and a second flow path 22 through which cooling water (second fluid) flows; and inner fins 40 disposed in the first flow path 21. The inner fin 40 has: a flat wall 41 in contact with the tube 50; a vertical wall 42 connected in the intersecting direction of the flat wall 41 and dividing the first flow path 21 into a plurality of small flow paths 23 arranged in the Y-axis direction (flow path width direction); and

fin portions

43 and 44 cut and raised from the flat wall 41 and protruding toward the small flow path 23. The tube 50 has opposing grooves 77 and longitudinal grooves 73, 93 (grooves) that are recessed from the flow path surface 63 facing the first flow path 21 and rise from the flow path surface 62 facing the second flow path 22.

According to the above configuration, in the heat exchanger 100, the inner fin 40 and the tube 50 transfer heat between the exhaust gas and the cooling water, but the contact area between the tube 50 and the inner fin 40 is reduced by providing the

depressions

77c, 73c, 93c of the opposed groove 77 and the

longitudinal grooves

fin portions

The pipe 50 is provided with opposing grooves 77 as grooves that extend across the small flow paths 23 across the plurality of flat walls 41 and face the flow of the cooling water (second fluid).

According to the above configuration, the cooling water flowing through the second flow path 22 in the X-axis direction passes over the opposed grooves 77 disposed so as to cross the second flow path 22, and becomes a vortex flow. Thus, in the heat exchanger 100, by generating a vortex flow in the flow of the cooling water, heat transfer from the cooling water to the tubes 50 can be promoted.

Further, the opposed groove 77 has: a pair of inclined portions 77a inclined with respect to the X-axis direction (flow path direction) and facing the flow of the cooling water (second fluid); and an intersection 77b where the paired inclined portions 77a intersect with each other.

According to the above configuration, the cooling water flowing through the second flow path 22 passes over the intersection 77b and the inclined portion 77a inclined with respect to the X-axis direction to form a vortex. Thus, in the heat exchanger 100, the longitudinal vortex flow is generated in the flow of the cooling water by the opposing grooves 77, thereby reducing the flow resistance of the cooling water and promoting the heat transfer from the cooling water to the tubes 50.

The tube 50 has

longitudinal grooves

73, 93 extending in the X-axis direction (flow path direction) as grooves. A plurality of opposing grooves 77 are aligned along the opposing grooves 77.

According to the above configuration, the cooling water flowing through the second flow path 22 flows in the X-axis direction along the

vertical grooves

73, 93. By arranging the plurality of opposing grooves 77 so as to be aligned along the opposing grooves 77, the cooling water flows as a vortex each time it passes over the opposing grooves 77. Thus, in the heat exchanger 100, the cooling water is generated so as to be aligned in the X-axis direction, and thus, the heat transfer from the cooling water to the tubes 50 can be promoted.

The

longitudinal grooves

73, 93 face each other in the Z-axis direction (stacking direction) and protrude toward the second flow path 22.

According to the above configuration, the cooling water flowing through the second flow path 22 flows along the pair of

vertical grooves

73 and 93 facing each other, and the potential energy flowing in the X-axis direction increases, and a strong vortex is formed each time the cooling water passes over the plurality of facing grooves 77 arranged along the

vertical grooves

73 and 93. Thereby, heat transfer from the cooling water to the tubes 50 can be promoted. Further, the opposed grooves 77 are formed only in one of the pair of tubes 50 stacked on each other, whereby the flow resistance of the cooling water can be suppressed.

The

fin openings

45 and 46, which are opened at the positions where the

fin portions

43 and 44 of the inner fin 40 are cut and raised, have portions facing the opposed grooves 77 of the tube 50 and the

recesses

77c, 73c, and 93c of the longitudinal grooves 73 and 93 (grooves).

By providing the opposed grooves 77 and the longitudinal grooves 73 and 93 (grooves) in the tube 50, the ratio a of the non-contact area of the tube 50 not in contact with the inner fins 40 is set in the range of 2% to 14%.

According to the above configuration, in the heat exchanger 100, the suppression of the non-contact area between the tubes 50 and the inner fins 40 by the

depressions

77c, 73c, 93c of the opposing grooves 77, the

longitudinal grooves

73, 93 can be sufficiently obtained, and the effect of promoting the heat transfer from the cooling water to the tubes 50 by the flow (vortex) of the cooling water guided to the opposing grooves 77, the

longitudinal grooves

Next, a modification of the pipe 50 shown in fig. 8 will be described.

The tube 50 of the above embodiment is configured such that the opposing grooves 77 are formed in the upper plate 60 and no opposing grooves are formed in the lower plate 80. In contrast, the tube 50 of the present modification is configured such that the opposing groove 77 is formed in the upper plate 60 and the opposing groove 97 is also formed in the lower plate 80.

The opposing grooves 77 of the upper plate 60 and the opposing grooves 97 of the lower plate 80 have the same V-shape and are arranged at the same position in the Z-axis direction. The intersection 77b of the opposing grooves 77 and the intersection (not shown) of the opposing grooves 97 are arranged at the same position in the Z-axis direction.

The heat exchanger 100 of the present modification is configured such that the paired facing

concave grooves

77 and 97 face each other in the Z-axis direction and protrude toward the second flow path 22.

According to the above configuration, the cooling water flowing through the second flow path 22 flows across the pair of

opposed grooves

77, 97 opposed to each other, thereby increasing the potential energy of the vortex flow. Thereby, heat transfer from the cooling water to the tubes 50 can be promoted.

Although the embodiments of the present invention have been described above, the above embodiments are merely some of application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the above embodiments.

For example, although the opposed grooves 77 (vortex generating grooves) of the above embodiment are raised in a V shape, the present invention is not limited thereto, and may be raised in a W shape. The opposed grooves 77 of the W shape have two pairs of inclined portions and two intersecting portions. In this case, the region where the longitudinal vortex of the cooling water is generated by the opposing grooves 77 is enlarged in the Y-axis direction, and the effect of promoting the heat transfer from the cooling water to the tubes 50 can be enhanced.

Further, the

fin portions

43 and 44 of the above embodiment are cut and raised in a trapezoidal shape having four sides, but the invention is not limited thereto, and may be cut and raised in a polygonal shape having five or more sides, for example.

The present invention is suitable for a heat exchanger mounted on a vehicle, but can also be applied to a heat exchanger used in a vehicle other than the vehicle.

The application claims priority of special application 2018- > 136947, based on the introduction of date 20/7/2018 to the office of this franchise, the entire content of which is incorporated by reference into the description of the present application.

Claims

1. A heat exchanger for exchanging heat between a first fluid and a second fluid, comprising:

a tube that partitions a first flow path through which a first fluid flows in a flow path direction and a second flow path through which a second fluid flows; and

an inner fin disposed in the first flow path,

the inner fin has:

a flat wall in contact with the tube;

a vertical wall connected in the intersecting direction of the flat walls and dividing the first flow path into a plurality of small flow paths arranged in the flow path width direction; and

a fin portion cut and raised from the flat wall so as to protrude toward the small flow path,

the tube has: opposed grooves that are recessed from a flow path surface facing the first flow path and raised from a flow path surface facing the second flow path, and that extend across the small flow paths across the plurality of flat walls and face a flow of the second fluid,

the opposed grooves have:

a pair of inclined portions inclined with respect to the flow path direction; and

and an intersection portion where the pair of inclined portions intersect with each other.

2. The heat exchanger of claim 1,

the pair of opposed grooves are opposed to each other and project toward the second flow path.

3. A heat exchanger for exchanging heat between a first fluid and a second fluid, comprising:

an inner fin disposed in the first flow path,

the inner fin has:

a flat wall in contact with the tube;

a fin portion cut and raised from the flat wall and protruding toward the small flow path,

the tube has:

opposed grooves that are recessed from a flow path surface facing the first flow path and raised from a flow path surface facing the second flow path, and that extend across the small flow paths and across the plurality of flat walls and face a flow of the second fluid; and

a longitudinal groove that is recessed from a flow path surface facing the first flow path and raised from a flow path surface facing the second flow path, and extends in the flow path direction,

a plurality of the opposed grooves are arranged along the longitudinal groove.

4. The heat exchanger of claim 3,

the pair of longitudinal grooves are opposed to each other and protrude toward the second flow path.

5. A heat exchanger for exchanging heat between a first fluid and a second fluid, comprising:

an inner fin disposed in the first flow path,

the inner fin has:

a flat wall in contact with the tube;

the tube has a groove recessed from a flow path surface facing the first flow path and raised from a flow path surface facing the second flow path,

by providing the groove in the tube, the proportion of the non-contact area of the tube not in contact with the inner fin is set in the range of 2% to 14%.