JP3912080B2 - Exhaust heat exchanger - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust heat exchange device that exchanges heat between exhaust gas discharged from an internal combustion engine and a cooling fluid, and an EGR gas heat exchange device (EGR) that cools exhaust gas for an EGR (exhaust gas recirculation device). It is effective when applied to a gas cooler.
[0002]
[Prior art and problems to be solved by the invention]
FIG. 11 shows an inner fin for an EGR gas cooler that the applicant has been experimentally examining. This inner fin is arranged in a tube through which the EGR gas flows and promotes heat exchange between the EGR gas and cooling water. is there.
[0003]
In the inner fin according to this prototype, a part of the inner fin is cut and raised to provide a triangular protrusion, that is, a wing protrusion 111c, thereby disturbing the flow of the EGR gas circulating in the tube and generating a vortex. While improving the heat transfer coefficient between the inner fin and the EGR gas, the gas flow rate in the vicinity of the inner fin is increased to blow away unburned substances such as particulate matter (soot) adhering to the inner fin, so that the PM becomes the inner fin. Prevents accumulation.
[0004]
However, since the inner fin according to this prototype is formed so that the cross-sectional shape viewed from the flow direction of the EGR gas has a rectangular wave shape, the gas passage in the tube 110 has an inner fin as shown in FIG. 111 is a state of being partitioned into a plurality of passages. Moreover, since the protrusion 111c is provided continuously in only one side of the partitioned passages by inner fins 111, many of the EGR gas flowing in the tube 110, the passages partitioned by the inner fin 1 11 Among them, it circulates on the side (upper side in FIG. 13) on which the protrusions with low flow resistance are not provided.
[0005]
For this reason, since the EGR gas that collides with the protrusion 111c is reduced, the flow of the EGR gas circulating in the tube cannot be sufficiently disturbed to generate vortices, and a sufficient effect, that is, an improvement in heat transfer coefficient. And PM deposition prevention could not be obtained.
[0006]
In view of the above points, an object of the present invention is to improve heat transfer coefficient and prevent PM accumulation in an exhaust heat exchanger.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an exhaust heat exchange device for exchanging heat between exhaust gas discharged from an internal combustion engine and a cooling fluid. a tube constituting the exhaust passage (110a) to (110), disposed within the tube, a first flat portion contacting the inner wall of the tube and (111a), a second flat plate which partitions the inside tube into a plurality of passages And a fin (111) formed so that a cross-sectional shape viewed from the flow direction of the exhaust has a wave shape, and the fin (111) includes a part of the first flat plate portion. Has a surface (S) inclined with respect to the exhaust flow, and the projecting dimension from the first flat plate portion increases as the shape of the surface moves toward the downstream side of the exhaust flow. Protrusions (111c) that are shaped Ri, protrusions at different positions in the flow direction of the exhaust, first, as the second protrusion is present protruding direction are opposite of each other, are arranged along the flow direction of the exhaust It is characterized by that.
[0008]
As a result, it is difficult for the phenomenon that the exhaust gas circulates only in the portion of the exhaust passage (110a) where the projection portion (111c) is not provided and the flow resistance is small, and the exhaust collides with the projection portion (111c). Since it flows while meandering, the exhaust can collide with the protrusion (111c) substantially evenly when observed as the whole exhaust passage (1110a).
[0009]
Therefore, since the exhaust flow can be reliably disturbed to generate vortices, the heat transfer coefficient between the fin (111) and the exhaust is improved, and the vicinity of the wall surface of the fin (111) and the exhaust passage (110a). To increase the gas flow rate and blow off unburned substances such as PM adhering to the wall surfaces of the fin (111) and the exhaust passage (110a) to deposit PM on the wall surface of the fin (111) and the exhaust passage (110a). Can be prevented.
[0012]
In the first aspect of the present invention, the protrusion (111c) has a surface (S) that is inclined with respect to the exhaust flow so that the protrusion dimension from the fin (111) increases toward the exhaust flow downstream side. It is .
[0013]
As a result, the exhaust gas flowing through the exhaust passage (110a) collides with the projection (111c) and then flows downstream so as to get over the collided projection (111c).
[0014]
At this time, the exhaust pressure on the surface of the protrusion (111c) on which the exhaust collides (hereinafter, this surface is referred to as a collision surface) is the opposite surface (hereinafter, this surface is referred to as the back surface). ) Higher than the exhaust pressure in For this reason, a part of the exhaust gas colliding with the collision surface flows into the back surface where the exhaust pressure is low beyond the projection portion (111c), so that the exhaust flow flowing without colliding with the projection portion (111c) is drawn into the back surface. A continuous vertical vortex, that is, a vortex that appears to vortex in a plane perpendicular to the exhaust flow when viewed from the exhaust flow, is generated.
[0015]
Therefore, since the exhaust gas flowing in the vicinity of the flat plate portion (111a) is accelerated so as to be boosted by the continuous vertical vortex that is drawn between the protrusions (111c), the exhaust gas flowing in the vicinity of the wall surface of the fin (111). However, it becomes larger than a simple wavy straight fin that does not have the protrusion (111c).
[0016]
As a result, the heat transfer coefficient between the exhaust and the fin (111) can be improved, and the PM adhering to the surface of the fin (111) can be blown away, thereby preventing clogging of the fin (111). Meanwhile, the heat exchange efficiency of the exhaust heat exchange device can be improved.
[0017]
The invention according to claim 3 is an exhaust heat exchange device for exchanging heat between the exhaust discharged from the internal combustion engine and the cooling fluid, and a tube (110 ) constituting the exhaust passage (110a) through which the exhaust flows. ) and is disposed within the tube, a first plate portion which contacts the inner wall of the tube and (111a), a second plate portion which partitions the inside tube into a plurality of passages and (111b), the flow of the exhaust And a fin formed so that the cross-sectional shape viewed from the direction is wavy, and the fin has a part of the first flat plate portion cut and raised toward the inside of the passage to prevent the exhaust flow. has a plane inclined (S), a projecting dimension becomes large shape from the first plate portion as the shape of the surface is directed to the exhaust gas flow downstream side, and arranged in a zigzag form along the exhaust gas flow fin side protrusions (111c) is provided, the tube A tube-side protrusion (110c) that protrudes toward the inside of the passage is provided on the inner wall surface facing the fin-side protrusion, and the fin-side protrusion and the tube-side protrusion are arranged in the exhaust flow direction. And are arranged so as to be shifted from each other .
[0018]
As a result, the exhaust gas collides with the protrusion (111c) and flows in the exhaust passage (110a) while meandering in the direction intersecting with the longitudinal direction of the exhaust passage (110a). Since the exhaust flow can be reliably disturbed to generate vortices, the gas flow rate in the vicinity of the fin (111) is increased to improve the heat transfer coefficient between the fin (111) and the exhaust, thereby improving the fin (111). It is possible to prevent PM from accumulating on the fin (111) by blowing off unburned substances such as PM adhering to the fin (111).
[0020]
The invention according to claim 5, when viewed from the direction perpendicular to the longitudinal direction of the exhaust passage (110a), that the fin-side projections (111c) and the tube-side projection and (110c) are located alternately Features.
[0021]
Thereby, it is possible to reliably increase the gas flow rate in the vicinity of the fin (111) and blow off unburned substances such as PM adhering to the fin (111) to prevent PM from being deposited on the fin (111). .
[0022]
Incidentally, as in the invention described in claim 6, it may be integrally formed on the member constituting the exhaust passage (110 a) tube-side protruding portion (110c).
[0023]
Also, as in the invention described in claim 7, it may be formed launch of a member constituting the exhaust passage (110 a) tube-side protruding portion (110c) by press molding.
[0024]
Incidentally, the reference numerals in parentheses of each means described above are an example showing the correspondence with the specific means described in the embodiments described later.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
In the present embodiment, the exhaust heat exchanger according to the present invention is applied to an EGR gas cooling device for a diesel engine, and FIG. 1 shows an EGR gas cooling device (hereinafter referred to as a gas cooler) according to the present embodiment. 1 is a schematic diagram of an EGR (exhaust gas recirculation device) using 100. FIG.
[0026]
The exhaust gas recirculation pipe 210 is a pipe that recirculates part of the exhaust gas discharged from the engine 200 to the intake side of the engine 200.
[0027]
The EGR valve 220 is provided in the middle of the exhaust gas flow in the exhaust gas recirculation pipe 210 and adjusts the amount of EGR gas according to the operating state of the engine 200. The gas cooler 100 is connected to the exhaust side of the engine 200 and the EGR side. It is arrange | positioned between the valves 220, and heat-exchanges between EGR gas and engine cooling water, and cools EGR gas.
[0028]
Next, the structure of the gas cooler 100 will be described.
[0029]
FIG. 2 is an external view (partially sectional view) of the gas cooler, and the tube 110 is a flat tube constituting the exhaust passage 110a through which the EGR gas flows, and the tube 110 has a predetermined shape as shown in FIG. It is formed by brazing and joining two plates 110b press-formed into a shape.
[0030]
Further, in the tube 110, that is, in the exhaust passage 110a, an inner fin 111 that promotes heat exchange between the EGR gas and the cooling water is disposed. As shown in FIG. It has two types of flat plate portions 111a and 111b extending in a strip shape in the gas flow direction and intersecting each other, and the cross-sectional shape viewed from the flow direction of the EGR gas is formed in a rectangular wave shape.
[0031]
And the flat part 111a which is a site | part which contacts the inner wall of the tube 110, ie, the plate 110b among the inner fins 111, by cutting up a part, the flat part of the inner fin 111 goes to the EGR gas flow downstream. Protrusions having a triangular surface S inclined with respect to the EGR gas flow, that is, wings 111c are provided so that the projecting dimension from 111a is increased.
[0032]
At this time, the wing 111c and the first wing 111c projecting in a first direction orthogonal to the flow direction of the EGR gas (the direction from the lower side to the upper side in FIG. 4) and the flow direction of the EGR gas. A second wing 111c protruding in a direction orthogonal to the first direction and different from the first direction (from the upper side to the lower side in FIG. 4) is partitioned by the inner fins 111. Along each exhaust passage 110a, a triangular surface S is provided so as to change in a staggered manner.
[0033]
Specifically, two wings 111c having different inclination directions of the surface S with respect to the EGR gas flow are arranged along the EGR gas flow, and a plurality of inner fins 111 having only the two wings 111c are arranged as EGR gas. The arrangement structure of the wings 111c described above is realized by arranging the tubes in the tube 110 while alternately inverting the arrangement direction (vertical direction) along the flow.
[0034]
Incidentally, the inner fin 111 and the tube 110 are formed by pressing a metal (in this embodiment, stainless steel) having excellent corrosion resistance, and the inner fin 111 and the tube 110 are integrally joined by brazing.
[0035]
In FIG. 2, the casing 120 houses a heat exchange core 113 in which a plurality of tubes 110 are stacked in the minor axis direction (up and down direction on the paper) and joined, and cooling water flows around the heat exchange core 113. The casing 120 is formed in the shape of a square pipe that forms the cooling water passage 121, and the casing 120 is made of a metal (in this embodiment, stainless steel) having excellent corrosion resistance.
[0036]
A tank portion 122a for distributing and supplying EGR gas to each tube 110 is formed at an opening on one end side (right side in the drawing) of the casing 120 in the longitudinal direction, and an EGR gas pipe (not shown) is connected to the opening. The joint portion 122 is brazed, and on the other hand, a tank portion 123a that collects and collects the EGR gas after heat exchange from each tube 110 is formed in the opening portion on the other end side in the longitudinal direction (left side in the drawing). A joint portion 123 for connecting a pipe (not shown) is brazed.
[0037]
The core plate 124 holds the tube 110 and partitions the cooling water passage 121 and the tank portions 122a and 123a. The core plate 124 and the joint portions 122 and 123 are also made of a metal having excellent corrosion resistance (this embodiment). Then, it is made of stainless steel.
[0038]
Further, an inlet 125 for introducing cooling water into the cooling water passage 121 from the longer diameter direction side of the tube 110 is provided on the EGR gas inflow side of the casing 120, and on the EGR gas outflow side of the casing 120. In addition, an outlet 126 for discharging the cooling water after the heat exchange is provided from the short diameter direction side of the tube 110 is provided.
[0039]
In the present embodiment, the direction of the EGR gas in the casing 120 and the direction of the cooling water flow are the same, and the long diameter of the tube 110 on the outer wall side of the tube 110 as shown in FIG. Protruding portion 110d extending in the direction is provided, and in the cooling water passage 121, the vicinity of the inlet 125 is partitioned into a relatively small space to constitute a speed increasing means for increasing the flow rate of the cooling water in the vicinity of the EGR gas inlet. The positioning means for ensuring the gap dimension between the tubes 110 is configured.
[0040]
Incidentally, in FIG. 5, the protrusion 110 e is for securing a gap between the tubes 110 and brazing the tube 110 and the inner fin 111 securely. In FIG. 2, the reinforcing rib 120 e is a reinforcement of the casing 120. It is for.
[0041]
Next, features of the present embodiment will be described.
[0042]
FIG. 6 is a schematic diagram showing an EGR gas flow in the exhaust passage 110a partitioned by the inner fins 111 in the gas cooler 100 according to the present embodiment. As is apparent from FIG. A first wing 111c that protrudes in a first direction orthogonal to the flow direction of the gas, and a second that protrudes in a direction orthogonal to the flow direction of the EGR gas and different from the first direction. Since the wing 111c is provided, the EGR gas collides with the wing 111c and flows in the exhaust passage 110a while meandering in a direction D1 orthogonal to the longitudinal direction Do of the exhaust passage 110a.
[0043]
Therefore, the phenomenon that the EGR gas flows only in a portion where the wing 111c is not provided in the exhaust passage 110a and the flow resistance is small is unlikely to occur. As described above, the EGR gas collides with the wing 111c and meanders. Since it flows, the EGR gas can collide with the wing 111c substantially evenly when observed as the entire tube 110.
[0044]
As a result, the flow of the EGR gas can be reliably disturbed to generate vortices, so that the heat transfer coefficient between the inner fin 111 and the EGR gas can be improved, and the vicinity of the inner fin 111 and the wall surface of the tube 110 can be improved. It is possible to prevent the PM from being deposited on the inner fin 111 and the wall surface of the tube 110 by increasing the gas flow rate and blowing off unburned substances such as PM adhering to the inner fin 111 and the wall surface of the tube 110.
[0045]
(Second Embodiment)
In the first embodiment, by disposing a plurality of inner fins 111 having only two wings 111c in the tube 110 while alternately inverting the arrangement direction (vertical direction) along the EGR gas flow, Although the above-described arrangement structure of the wings 111c has been realized, in the present embodiment, as shown in FIG. 7, the flat plate portions 111b, that is, the portions of the inner fins 111 that are substantially parallel to the minor axis direction of the tube 110 are arranged in a staggered manner. A first wing 111c protruding in a first direction perpendicular to the flow direction of EGR gas with respect to the offset inner fin, and a direction perpendicular to the flow direction of EGR gas, There is a second wing 111c that protrudes in a direction different from the first direction.
[0046]
And in this embodiment, since the inner inner fin can be comprised with the one inner fin 111, the manufacturing man-hour of the gas cooler 100 can be reduced.
[0047]
(Third embodiment)
In this embodiment, the exhaust passage 110a and the cooling water passage 121 are partitioned to form a plate 110b constituting the exhaust passage 110a. As shown in FIG. 8, a part of the plate 110b is press-molded inside the exhaust passage 110a. The protrusion 110c is provided by punching.
[0048]
Then, as shown in FIG. 9A, a plurality of these projecting portions 110c are staggered along the exhaust flow while being inclined with respect to the exhaust flow on the wall surface facing the wing 111c in the exhaust passage 110a. As shown in FIG. 9B, the wings 111c and the protrusions 110c are alternately positioned as seen from the direction orthogonal to the longitudinal direction of the exhaust passage 110a. Incidentally, FIG. 10 is an external view of the tube 110 according to the present embodiment.
[0049]
Thus, as in the first embodiment, the EGR gas collides with the wing 111c and the protrusion 110c and flows in the exhaust passage 110a while meandering in a direction perpendicular to the longitudinal direction of the exhaust passage 110a.
[0050]
Therefore, the phenomenon that EGR gas circulates only in the portion of the exhaust passage 110a where the wing 111c or the protrusion 110c is not provided and the flow resistance is small is unlikely to occur, and the EGR gas collides with the wing 111c and meanders. Since it flows, the EGR gas can collide with the wing 111c substantially evenly when observed as the entire tube 110.
[0051]
As a result, the flow of the EGR gas can be reliably disturbed to generate vortices, so that the heat transfer coefficient between the inner fin 111 and the EGR gas can be improved, and the vicinity of the inner fin 111 and the wall surface of the tube 110 can be improved. It is possible to prevent the PM from being deposited on the inner fin 111 and the wall surface of the tube 110 by increasing the gas flow rate and blowing off unburned substances such as PM adhering to the inner fin 111 and the wall surface of the tube 110.
[0052]
In the present embodiment, the angle θ1 formed by the wing 111c and the EGR gas streamline is made equal to the angle θ2 formed by the protrusion 110c and the EGR gas streamline. However, the present embodiment is not limited to this. is not.
[0053]
In this embodiment, the projecting dimension of the protrusion 110c is made smaller than the maximum projecting dimension of the wing 111c, but the present embodiment is not limited to this.
[0054]
(Other embodiments)
In the above-described embodiment, the wing 111c has a triangular shape, but the present invention is not limited to this, and may have other shapes such as a rectangular shape or a hemispherical (dome) shape.
[0055]
In the above-described embodiment, the exhaust heat exchanger according to the present invention is applied to the gas cooler 100. However, the heat exchanger such as a heat exchanger that is disposed in the muffler and collects the heat energy of the exhaust is also used. You may apply.
[0056]
Further, in the above-described embodiment, the wing 111c is formed by cutting and raising a part of the inner fin 111. However, the present invention is not limited to this, and the wing is separated from the inner fin 111 and a separate plate-like member. 111c may be formed, and the plate-like member on which the wing 111c is formed may be joined to the inner fin 111 by joining means such as brazing to form the wing 111c.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an EGR gas cooling apparatus using a gas cooler according to a first embodiment of the present invention.
FIG. 2 is an external view of a gas cooler according to the first embodiment of the present invention.
FIG. 3 is a sectional view of the tube of the gas cooler according to the first embodiment of the present invention.
FIG. 4 is a perspective view of an inner inner fin of the gas cooler according to the first embodiment of the present invention.
FIG. 5 is a half sectional view of the tube of the gas cooler according to the first embodiment of the present invention.
FIG. 6 is an explanatory diagram for explaining the characteristics of the gas cooler according to the first embodiment of the present invention.
FIG. 7 is a perspective view of an inner inner fin of a gas cooler according to a second embodiment of the present invention.
FIG. 8 is a sectional view of a tube of a gas cooler according to a third embodiment of the present invention.
FIG. 9A is an explanatory view for explaining the characteristics of a gas cooler according to a third embodiment of the present invention, and FIG. 9B is a top view of FIG. 9A.
FIG. 10 is a two-sided external view of a tube 110 according to a third embodiment of the present invention.
FIG. 11 is a perspective view of an inner inner fin of a gas cooler according to a prototype study.
FIG. 12 is a cross-sectional view of a gas cooler tube according to a prototype study.
FIG. 13 is an explanatory diagram for explaining the characteristics of the gas cooler according to the trial examination.
[Explanation of symbols]
111 ... Inner inner fin, 111c ... Wing (projection).

Claims (7)

An exhaust heat exchange device for exchanging heat between exhaust gas discharged from an internal combustion engine and a cooling fluid,
A tube (110) constituting an exhaust passage (110a) through which exhaust flows,
Disposed within said tube has a first flat portion contacting the inner wall of the tube and (111a), a second plate portion which partitions the inside of the tube into a plurality of passages and (111b), the flow of the exhaust A fin (111) formed so that a cross-sectional shape viewed from the direction is wavy,
The fin (111) has a surface (S) inclined with respect to the exhaust flow by part of the first flat plate portion being cut and raised toward the inside of the passage, and the shape of the surface Is provided with a protrusion (111c) having a shape in which the protrusion dimension from the first flat plate portion increases toward the exhaust flow downstream side,
The protrusions are arranged along the exhaust flow direction so that there are first and second protrusions whose protrusion directions are opposite to each other at different positions in the exhaust flow direction . Exhaust heat exchange device characterized by. The exhaust heat exchanger according to claim 1 , wherein the protrusions (111c) are provided in a staggered manner along the exhaust flow . An exhaust heat exchange device for exchanging heat between exhaust gas discharged from an internal combustion engine and a cooling fluid,
A tube (110) constituting an exhaust passage (110a) through which exhaust flows,
A first flat plate portion (111a) disposed in the tube and in contact with the inner wall of the tube, and a second flat plate portion (111b) for partitioning the inside of the tube into a plurality of passages, and circulation of exhaust gas With fins formed so that the cross-sectional shape seen from the direction is wavy,
The fin (111) has a surface (S) inclined with respect to the exhaust flow by part of the first flat plate portion being cut and raised toward the inside of the passage, and the shape of the surface Is provided with fin-side projections (111c) arranged in a staggered manner along the exhaust flow, with the projecting dimension from the first flat plate portion increasing toward the downstream side of the exhaust flow.
An inner wall surface facing the fin-side protrusion of the tube is provided with a tube-side protrusion (110c) protruding toward the inside of the passage,
The exhaust heat exchanger according to claim 1, wherein the fin-side protrusion and the tube-side protrusion are arranged so as to be shifted from each other along a flow direction of the exhaust. The exhaust heat exchanger according to claim 3, wherein a plurality of the tube side protrusions (110c) are arranged in a staggered manner along the exhaust flow while being inclined with respect to the exhaust flow. When viewed from a direction perpendicular to the longitudinal direction of the exhaust passage (110a), according to claim 3, wherein the fin-side protrusion and (111c) said tube-side projection and (110c), characterized in that the positioned alternately Or the exhaust heat exchanger according to 4 . The tube-side projections (110c), the exhaust passage (110 a) exhaust heat exchange apparatus according to any one of claims 3 to 5, characterized in that integrally formed on the member constituting the. The tube-side projections (110c), the exhaust heat exchanger according to any one of claims 3 to 5, characterized in that has sprung from the member constituting the exhaust passage (110 a) by press molding apparatus.

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