JP3879614B2 - Heat exchanger - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat exchanger, and is applied to an exhaust heat exchange device that exchanges heat between exhaust gas generated by combustion and a cooling fluid, for example, a gas cooler that cools exhaust gas for an EGR (exhaust gas recirculation device). It is valid.
[0002]
[Prior art and problems to be solved by the invention]
FIG. 2 is an external view (partial cross section) of the gas cooler that the applicant has studied and prototyped, FIG. 7 is a cross-sectional view taken along the line AA in FIG. 2, and FIG. 8 is an enlarged view of a portion A in FIG. In addition, FIG. 2 is a figure used for description of embodiment of this invention, A subject is demonstrated using this FIG.
[0003]
As shown in FIG. 7, the gas cooler according to this prototype study is a heat exchange comprising a pipe-shaped casing 20 that constitutes a fluid passage 16 through which cooling water flows, and a plurality of tubes 11 and inner fins 12 through which exhaust flows. those constructed and a core 15.
[0004]
Further, as shown in FIG. 2, the heat exchange core 15, that is, the tube 11, has its longitudinal end inserted into the core plate 23 and fixed to the casing 20 via the core plate 23.
[0005]
By the way, when inserting the tube 11 into the core plate 23, it is necessary to provide an insertion hole 23a for inserting the tube 11 into the core plate 23. However, considering the insertion and assembling property of the tube 11, as shown in FIG. In addition, it is desirable to make the radius of curvature R1 of the corner of the tube 11 as large as possible.
[0006]
Incidentally, when the curvature radius R1 of the corner portion is reduced, it becomes difficult to insert the tube 11 into the insertion hole 23a, and processing (for example, punching by press) for opening the insertion hole 23a is deteriorated.
[0007]
However, if the radius of curvature R1 of the corner portion is increased, the range of the curved surface at the corner portion of the tube 11 is increased. Therefore, the inner fin 12 is attached to the tube 11 so that the end portion of the inner fin 12 is brought into contact with the corner portion of the tube 11. Therefore, there is a problem that the fixing position of the inner fin 12 varies greatly with respect to the tube 11 after the completion of brazing.
[0008]
In view of the above points, the present invention firstly provides a novel heat exchanger different from the conventional one, and secondly, it is intended to prevent the fixing position of the inner fin from greatly varying with respect to the tube. And
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a pipe-shaped casing (20) constituting a fluid passage (16) through which a fluid flows,
A heat exchange core (15) having a tube (11) that is housed in the casing (20) and through which a fluid that exchanges heat with the fluid flowing in the casing (20) flows;
A fin (12) provided in the tube (11) for generating a vortex flow to improve the heat transfer rate;
A core plate (23) having an insertion hole (23a) into which the longitudinal end of the tube (11) is inserted, and fixing the tube (11) to the casing (20);
The tube cross-section corner at the longitudinal end (11f) of the tube (11) is a shape having a radius of curvature,
In the tube (11), the tube cross-section corner at the position shifted from the longitudinal end (11f) to the longitudinal center is projected from the outside of the tube (11) and protrudes inward. 11e) is provided by plastic working,
Furthermore, the fin (12) is positioned in the tube (11) by the protrusion (11e).
[0010]
Thereby, in the tube (11), the shape of the tube cross-section corner is a shape having a radius of curvature at the longitudinal end (11f) inserted into the insertion hole (23a) of the core plate (23), Of the tube (11), a protrusion (11e) that protrudes inward is provided at the corner of the tube cross section at a position shifted from the longitudinal end (11f) to the longitudinal center. The protrusion (11e) The fin (12) can be positioned.
Therefore, the fin (12) can be reliably positioned with respect to the tube (11) without reducing the curvature radius R1 of the cross-sectional corner of the longitudinal end (11f) of the tube (11).
[0011]
As described above, since the fin positioning function can be achieved by the protrusion (11e), the tube cross-section corner at the end (11f) in the longitudinal direction of the tube (11 ) , that is, the portion inserted into the insertion hole (23a). The radius of curvature R1 can be made sufficiently large . For this reason, the insertion assembly property of a tube (11) does not deteriorate.
[0012]
Therefore, it is possible to prevent the fixing positions of the fins (12) from greatly varying with respect to the tube (11) without impairing the insertion and assembling property of the tube (11) and the workability of the core plate (23). A new heat exchanger can be obtained.
[0013]
In the invention according to claim 2, the tube (11) has a flat cross-sectional shape as viewed from the longitudinal direction thereof, and the protrusion (11e) is formed on the end of the cross-sectional shape in the long-diameter direction. It is characterized by being provided.
[0014]
In the invention according to claim 3, the tube (11) is configured by combining two plate members (11b) press-molded into a predetermined shape, and the protrusion (11e) is formed by combining the plate member (11b). ) Is formed by press molding.
[0015]
In the invention according to claim 4, the exhaust gas generated by combustion flows in the tube (11), and the fin (12) has a substantially wave-like cross-sectional shape as viewed from the longitudinal direction of the tube (11). In addition, a projecting dimple (11d) protruding inward is provided in a portion of the tube (11) where the fin (12) is not disposed.
[0016]
As a result, the fin (12) can be arranged and fixed at a predetermined position with respect to the tube (11), so that the distance between the dimple (11d) and the side surface of the fin (12) becomes excessively small or larger than necessary. Can be prevented in advance.
[0017]
Therefore, PM such as soot can be prevented from accumulating between the dimple (11d) and the wall (12b), and a vortex can be reliably generated. The heat transfer coefficient between the two can be improved. As a result, the heat exchange capability of the heat exchanger can be improved.
[0018]
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.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
In the present embodiment, the heat exchanger according to the present invention is applied to a diesel-type exhaust cooling device for an engine. FIG. 1 uses an exhaust cooling device (hereinafter referred to as a gas cooler) 10 according to the present embodiment. 1 is a schematic diagram of an EGR (exhaust gas recirculation device).
[0020]
The exhaust gas recirculation pipe 30 is a pipe for returning a part of the exhaust gas discharged from the engine 31 to the intake side of the engine 31.
[0021]
The EGR valve 32 is provided in the middle of the exhaust gas flow in the exhaust gas recirculation pipe 30 and adjusts the amount of exhaust gas according to the operating state of the engine 31. The gas cooler 10 is connected to the exhaust side of the engine 31 and the EGR valve. Between the exhaust gas and the engine coolant to exchange heat and cool the exhaust gas.
[0022]
Next, the structure of the gas cooler 10 will be described.
[0023]
2 is an external view (partial cross-sectional view) of the gas cooler, FIG. 3 is a cross-sectional view taken along the line AA of FIG. 2, and FIG. 4 is an enlarged view of a portion A of FIG.
[0024]
In FIG. 2, a tube 11 is a flat tube that constitutes an exhaust passage 11a through which exhaust flows, and the tube 11 brazes two plates 11b press-molded into a predetermined shape as shown in FIG. It is formed by bonding.
[0025]
Further, in the tube 11, that is, in the exhaust passage 11a, an inner fin 12 that promotes heat exchange between the exhaust gas and the cooling water is disposed. As shown in FIG. It has two types of wall members 12a and 12b that extend in a strip shape in the flow direction and intersect each other, and the cross-sectional shape viewed from the flow direction of the exhaust gas is formed in a rectangular wave shape. For this reason, in the exhaust passage 11a, a plurality of narrow flow passages 11c that are partitioned in the short diameter direction of the tube 11 are configured.
[0026]
Further, the wall member 12a of the inner fin 12 is partly cut and raised so that the protruding dimension of the inner fin 12 from the wall member 12a increases toward the downstream side of the exhaust flow. Protrusions having inclined triangular surfaces, that is, wings 12c are formed in a staggered manner.
[0027]
On the other hand, the tube 11, that is, the portion of the plate 11 b where the inner fin 12 is not disposed, is a protrusion that protrudes inward by pressing as shown in FIGS. 3, 4, and 6 (b). A plurality of dimples 11d are formed along the exhaust flow, as shown in FIG. 6A, on the wall surface of the exhaust passage 11a facing the wing 12c.
[0028]
Further, as shown in FIG. 4, at the corner on the long-diameter end portion side of the tube cross section, a protruding portion 11e that is recessed in a substantially L shape from the outside to the inside of the tube 11 and protrudes to the inside is formed by pressing or the like. The inner fin 12 is provided by plastic working, and the inner fin 12 is positioned in the tube 11 by the protrusion 11e.
[0029]
Further, as shown in FIG. 6A, the protruding portion 11e is long from the other end 11f in the longitudinal direction of the tube 11 from a portion of the tube 11 shifted from the longitudinal one end 11f to the longitudinal central portion. The inner curvature radius R2 (see FIG. 4) of the protruding portion 11e is continuously formed over the portion shifted toward the center in the direction, and the curvature radius R1 of the cross-sectional corners of both end portions 11f in the longitudinal direction is larger. Small dimensions are set.
[0030]
Incidentally, the site to be inserted longitudinal end portion 11f of the tube 11, i.e. into the insertion hole 23a is conventionally a shape having the same Ku curvature radius R1 (see FIG. 8).
[0031]
Incidentally, the inner fin 12 and the tube 11 are formed by pressing a metal having excellent corrosion resistance (in this embodiment, stainless steel), and the inner fin 12 and the tube 11 are integrally joined by brazing.
[0032]
In FIG. 2, the casing 20 houses a heat exchange core 15 in which a plurality of tubes 11 are stacked in the minor axis direction (up and down direction on the paper surface) and joined, and cooling water flows around the heat exchange core 15. The casing 20 is formed in the shape of a square pipe that forms the cooling water passage 16, and the casing 20 is made of a metal (in this embodiment, stainless steel) having excellent corrosion resistance.
[0033]
A tank portion 21a that distributes and supplies exhaust gas to each tube 11 so as to close the opening portion is formed at the opening portion on one end side (right side of the paper surface) of the casing 20 in the longitudinal direction, and an exhaust gas recirculation pipe 30 is provided. A first bonnet 21 to be connected is brazed, and a tank portion 22a that collects and collects exhausted heat from each tube 11 is formed at the opening on the other end in the longitudinal direction (left side of the paper). In addition, a second bonnet 22 for connecting the exhaust gas recirculation pipe 30 is brazed.
[0034]
At this time, since the cross-sectional area of the exhaust inlet 21b formed in the first bonnet 21 is smaller than the cross-sectional area of the heat exchanger core 15, the first bonnet 21 has a passage cross-sectional area that is heated from the exhaust inlet 21b. It is formed in a trumpet shape so as to continuously and smoothly expand over the exchanger core 15. Similar to the eleventh bonnet 21, the second bonnet 22 is also formed in a trumpet shape so as to continuously and smoothly expand from the exhaust outlet 22b to the heat exchanger core portion 15.
[0035]
Further, the core plate 23 inserts the end portion in the longitudinal direction of the tube 11 into the insertion hole 23a to fix the tube 11 to the casing 20, and partitions the cooling water passage 16 from the tank portions 21a and 22a. The core plate 23 and the first and second bonnets 21 and 22 are also made of metal having excellent corrosion resistance (in this embodiment, stainless steel).
[0036]
An inflow port 24 for introducing cooling water into the cooling water passage 16 from the longer diameter direction side of the tube 11 is provided on the exhaust inflow side of the casing 20, and a tube is provided on the exhaust outflow side of the casing 20. 11 is provided with an outlet 25 for discharging the cooling water after the heat exchange.
[0037]
In the present embodiment, the exhaust direction in the casing 20 is the same as the direction of circulation and the direction of circulation of the cooling water, and a projection 11c extending in the major axis direction of the tube 11 is provided on the outer wall side of the tube 11. Thus, the vicinity of the inlet 24 in the cooling water passage 16 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 exhaust inlet, and the clearance between the tubes 11 is ensured. The positioning means is configured.
[0038]
Next, the effect of this embodiment is described.
[0039]
In the present embodiment, the inner fin 12 is positioned with respect to the tube 11 by applying the end of the inner fin 12 to the protrusion 11e instead of applying the end of the inner fin 12 to the corner of the tube 11. Therefore, the inner fin 12 can be reliably positioned with respect to the tube 11 without reducing the radius of curvature R1 of the corner portion of the tube 11.
[0040]
Moreover, since the curvature radius R1 can be enlarged at the longitudinal direction end of the tube 11, that is, the portion inserted into the insertion hole 23a as described above, the insertion and assembling property of the tube 11 does not deteriorate.
[0041]
Therefore, it is possible to prevent the fixing position of the inner fin 12 from greatly varying with respect to the tube 11 without impairing the insertion and assembling property of the tube 11 and the workability of the core plate 23.
[0042]
Further, since the inner fin 12 can be arranged and fixed at a predetermined position with respect to the tube 11, the distance between the dimple 11d and the side surface (wall portion 12b) of the inner fin 12 becomes excessively small or larger than necessary. Can be prevented.
[0043]
If the distance between the dimple 11d and the wall portion 12b is excessively small, PM such as soot is likely to be deposited, so that the gas cooler 10 is easily clogged. Further, if the distance between the dimple 11d and the wall portion 12b becomes excessively large, vortices are less likely to be generated, so that the heat transfer coefficient between the exhaust and the tube 11 (inner fin 12) is reduced, and the cooling capacity of the gas cooler 10 is reduced. Decreases.
[0044]
(Other embodiments)
The inner fin 12 is not limited to the straight fin shown in the above-described embodiment (see FIG. 4), and may be a known offset fin, for example.
[0045]
In the above-described embodiment, the exhaust heat exchange device according to the present invention is applied to the gas cooler 10, but other heat exchangers such as a heat exchanger that is disposed in the muffler and collects the heat energy of the exhaust gas are also used. You may apply.
[Brief description of the drawings]
FIG. 1 is a schematic view of an EGR gas cooling device using a gas cooler according to an embodiment of the present invention.
FIG. 2 is an external view of a gas cooler according to an embodiment of the present invention.
3 is a cross-sectional view taken along the line AA in FIG.
4 is an enlarged view of a part A in FIG. 3;
FIG. 5 is a perspective view of an inner fin according to an embodiment of the present invention.
6A is a front view of a tube according to an embodiment of the present invention, and FIG. 6B is a sectional view taken along line BB in FIG.
7 is a cross-sectional view corresponding to the AA cross section of FIG. 2 in the gas cooler according to the trial manufacture.
8 is an enlarged view of a part A in FIG. 7;
[Explanation of symbols]
11 ... Tube, 11d ... Dimple, 11e ... Projection for positioning,
12 ... Inner fin, 12c ... Wing.

Claims (4)

A pipe-shaped casing (20) constituting a fluid passage (16) through which a fluid flows;
A heat exchange core (15) having a tube (11) that is housed in the casing (20) and through which a fluid that exchanges heat with the fluid flowing in the casing (20) flows;
A fin (12) provided in the tube (11) for generating a vortex flow to improve the heat transfer rate;
A core plate (23) having an insertion hole (23a) into which the longitudinal end of the tube (11) is inserted, and fixing the tube (11) to the casing (20);
The tube cross-section corner at the longitudinal end (11f) of the tube (11) has a curvature radius,
The tube cross-section corners at a site offset in the longitudinal direction central portion side from the longitudinal end (11f) of said tube (11), projecting inwardly recessed from the outside to the inside of the tube (11) The protrusion (11e) is provided by plastic working,
Furthermore, the said fin (12) is positioned in the said tube (11) by the said projection part (11e), The heat exchanger characterized by the above-mentioned. The tube (11) has a flat cross-sectional shape as viewed from its longitudinal direction,
Furthermore, the said protrusion part (11e) is provided in the major-diameter direction edge part side of the said cross-sectional shape, The heat exchanger of Claim 1 characterized by the above-mentioned. The tube (11) is configured by combining two plate materials (11b) press-molded into a predetermined shape,
Furthermore, the said projection part (11e) is formed by performing press molding to the said board | plate material (11b), The heat exchanger of Claim 1 or 2 characterized by the above-mentioned. In the tube (11), exhaust gas generated by combustion flows,
As for the said fin (12), the cross-sectional shape seen from the longitudinal direction of the said tube (11) is formed in substantially wave shape,
Furthermore, a projecting dimple (11d) protruding inward is provided at a portion of the tube (11) where the fin (12) is not disposed. The heat exchanger according to any one of 3.

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