JP2013142486A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a great difference in exhaust gas flow rate among a plurality of surfaces contacted with exhaust gas without greatly lowering the flow rate of the exhaust gas even on a downstream side.SOLUTION: In a tube 2 through which exhaust gas flows, a first flat plate part 21 is disposed to abut on the inner wall of the tube 2. The first flat plate part 21 includes a surface inclined in an exhaust gas flowing direction by cutting-up and a first projection 31 and a second projection 32 are formed whose inclining directions are opposite each other. The projections 31 and 32 have larger projection sizes from the first flat plate part 21 as they advance respectively in the flowing-direction upstream side of the exhaust gas. The first projection 31 and the second projection 32 are, for example, alternately arranged in the flowing direction of the exhaust gas.

Description

  The present invention relates to a heat exchanger.

  In a heat exchanger such as an EGR cooler in which engine exhaust gas is circulated, generally, a plurality of tubes each having a flat inner space are provided between each other in an outer tube having a rectangular cross section. It arrange | positions in the lamination | stacking state so that it may ensure, and the both ends of each tube are being fixed in the state closely_contact | adhered to the outer tube. And, in the intermediate part between the fixed parts at both ends of each tube, for example, by enlarging the outer tube outward, it is possible to secure a large distribution space between each tube and the outer tube. Has been done. In such a heat exchanger, heat is exchanged between the exhaust gas flowing in each tube and the cooling medium (for example, cooling water or air) flowing in the circulation gap and the circulation space via each tube. It has become.

  In order to effectively perform heat exchange between the tube and the exhaust gas flowing through the tube, as shown in Patent Document 1, a first flat plate portion that abuts against the inner wall of the tube using a corrugated material having a square corrugated shape. And a second flat plate portion that partitions the inside of the tube into a plurality of portions, and a protrusion is formed by cutting and raising the first flat plate portion (increasing exhaust gas contact area). And in the thing of patent document 1, the cut-and-raised projection part is set so that the protrusion dimension from a 1st flat plate part may become small gradually toward the upstream of the distribution direction of exhaust gas. In addition, a hole formed in the first flat plate portion formed by cutting and raising the protrusion is positioned on the downstream side of the protrusion.

JP 2007-225190 A

  In the case where the first flat plate portion and the second flat plate portion are provided in the tube, and the protrusion portion inclined with respect to the flow direction of the exhaust gas is formed by cutting and raising the first flat plate portion, the flow rate of the exhaust gas is particularly high. It is desirable to maintain the exhaust gas flow rate as uniform as possible throughout the exhaust gas flow direction in order to prevent (suppress) soot accumulation on the lower stream side and to perform efficient heat exchange. It becomes. In particular, the exhaust gas flow rate should not be greatly different between the upstream side and the downstream side in the exhaust gas flow direction, or the exhaust gas flow rate may be increased between a plurality of wall surfaces such as the left and right wall surfaces and the opposing wall surfaces with respect to the first flat plate portion. It would be desirable to avoid large variations.

  The present invention has been made in consideration of the above-described circumstances, and the purpose thereof is to prevent the exhaust gas flow velocity from greatly decreasing even on the downstream side, and the exhaust gas between a plurality of surfaces in contact with the exhaust gas. It is an object of the present invention to provide a heat exchanger that does not cause a large difference in the flow rate of the heat exchanger.

In order to achieve the above object, the following solution is adopted in the present invention. That is, as described in claim 1,
A heat exchanger for exchanging heat between exhaust gas discharged from an engine and a cooling medium,
A tube having an internal space through which exhaust gas is circulated;
A first flat plate portion that is positioned in the tube and is in contact with the inner wall of the tube; a second flat plate portion that partitions the tube into a plurality of passages;
Have
The first flat plate portion has a surface that is inclined with respect to the flow direction of the exhaust gas by cutting and raising, and a first protrusion portion and a first protrusion portion whose inclination directions with respect to the flow direction of the exhaust gas are set to be opposite to each other. A large number of two protrusions,
Each of the first protrusion and the second protrusion is configured such that the protrusion dimension from the first flat plate portion increases toward the upstream side of the exhaust gas flow direction,
The first protrusion and the second protrusion are formed at different positions in the exhaust gas flow direction.
It is like that.

  According to the above-described solution technique, a large decrease in the exhaust gas flow velocity is suppressed, particularly on the downstream side, and variations in the exhaust gas flow velocity between the left and right wall surfaces and the opposed wall surfaces with respect to the first flat plate portion are also suppressed. As a result, soot accumulation can be prevented and heat exchange efficiency can be improved particularly on the downstream side where the exhaust gas flow rate is reduced.

A preferred mode based on the above solution is as described in claim 2 and the following claims. That is,
A first hole formed in the first flat plate portion by forming the first protrusion is located upstream of the first protrusion,
A second hole formed in the first flat plate portion by forming the second protrusion is positioned upstream of the second protrusion,
The first hole and the first hole are closed by the inner wall of the tube,
(Corresponding to claim 2). In this case, since the high-speed exhaust gas immediately before colliding with the protrusion passes through the hole, it is preferable for preventing the accumulation of soot in the hole.

Each of the first protrusion and the second protrusion is triangular,
Each of the first protrusions having the triangular shape has an angle θ1 formed by the first side on the upstream side in the exhaust gas flow direction with respect to the bottom side of the first flat plate portion on the downstream side in the exhaust gas flow direction. The second side is made larger than the angle θ2 made with respect to the bottom side of the flat plate portion,
(Corresponding to claim 3). In this case, a specific and preferable shape setting of each protrusion is provided.

  The first protrusions and the second protrusions are formed so as to be alternately positioned in the exhaust gas flow direction (corresponding to claim 4). In this case, each time one projection is passed, the flow direction of the exhaust gas is changed (increasing the number of times the exhaust gas meanders), which is preferable for further improving the heat exchange efficiency.

  The first projecting portion and the second projecting portion are arranged such that the arrangement interval in the exhaust gas flow direction is made smaller toward the downstream side (corresponding to claim 5). In this case, in the downstream part where the exhaust gas temperature is lowered and the heat exchange efficiency is deteriorated, the number of projections colliding with the exhaust gas is increased, which is preferable in improving the heat exchange efficiency.

  The first flat plate portion and the second flat plate portion are integrally formed by a corrugated plate material having a rectangular corrugated shape, and the first flat plate portion is brought into contact with a pair of opposed inner walls of the tube. (Claim 6). In this case, it is preferable in that the first flat plate portion and the second flat plate portion are simply and inexpensively configured. Further, the second flat plate portion is preferable for allowing the exhaust gas to flow as uniformly as possible in the tube, and also preferable for preventing the tube from being crushed and deformed.

  According to the present invention, it is possible to improve heat exchange efficiency while preventing soot accumulation.

Side surface sectional drawing which shows an example of the heat exchanger to which this invention was applied. The front view which looked at FIG. 1 from the left in the state which removed the connection member. The enlarged view which looked at the tube from the flow direction of exhaust gas. The principal part perspective view which shows the 1st projection part and the 2nd projection part which were formed in the 1st flat plate part. The top view of a 1st flat plate part. The side view which looked at the 1st projection part from the horizontal direction. The top view which shows an example which formed the 1st projection part and the 2nd projection part at unequal pitch paying attention to the hole part corresponding to each projection part. The figure which shows the exhaust gas flow velocity in the wall surface vicinity of a 1st flat plate part. The figure which shows the exhaust gas flow velocity in the wall surface vicinity of 3 surfaces except a 1st flat plate part. The figure which shows the dispersion | variation degree of the exhaust gas flow velocity between several wall surfaces in a downstream part.

  1 and 2, the heat exchanger H is an EGR cooler used in an automobile equipped with a gasoline engine or a diesel engine. 1 is an outer tube, 2 is a plurality of tubes, 3 and 4 are connecting members for supplying and discharging exhaust gas, and 5 and 6 are for supplying and discharging a cooling medium (for example, cooling water and cooling air) It is a connection pipe. The outer tube 1 has a split structure (see FIG. 2), and has a rectangular cross section (a quadrangular cylinder). A plurality of tubes 2 are provided, each having a flat rectangular shape, and a flat internal space 2a through which exhaust gas flows is defined.

  The plurality of tubes 2 are disposed in the outer tube 1 in a stacked state so that the wide surfaces thereof face each other. Each tube 2 is expanded at both end portions thereof, and the expanded portion is fixed in a close state to the outer tube 1 by, for example, brazing (airtightness between the outer tube 1 and each tube 2). And liquid-tightness is ensured). At both ends, the tubes 2 are in close contact with each other, and the tubes 2 and the outer tube 1 are in close contact with each other. As a result, the exhaust gas introduced from the connection member 3 flows only through the tubes 2 and is then discharged from the connection member 4. On the other hand, a cooling medium such as cooling water or cooling air is introduced from the connection pipe 5 into the outer pipe 1 and then discharged from the connection pipe 6 t. Heat exchange is performed between the exhaust gas and the cooling medium via the tube 2 (cooling of the exhaust gas). In FIG. 2, the inside of the tube 2 is shown in a simplified manner (the corrugated sheet material 10 described later is omitted).

  Next, the details of the tube 2 will be described with reference to FIGS. First, as shown in FIG. 3, a corrugated material 10 having a square corrugated shape is disposed in the tube 2. The corrugated material 10 constitutes a first flat plate portion 21 that contacts the inner wall (the inner surface of the wide surface) of the tube 2 and a second flat plate portion 22 that partitions the inside of the tube 2 into a plurality of passages. The first flat plate portion 21 is provided on each of the opposing wide surfaces of the tube 2, and the first flat plate portions 21 are connected by the second flat plate portion 22. In addition, the corrugated sheet material 10, the outer tube 1, and the tube 2 are formed of a metal (for example, iron-based metal, copper-based metal, or aluminum-based metal) having excellent heat transfer efficiency.

  A first projection 31 and a second projection 32 are formed on the first flat plate portion 21 by cutting and raising. Each of the first protrusion 31 and the second protrusion 32 has a triangular shape and is inclined with respect to the flow direction of the exhaust gas. The inclination direction of the first protrusion 31 and the inclination direction of the second protrusion 32 are opposite to each other.

  The first protrusion 31 will be described in detail with reference to FIGS. First, a first hole 41 is formed in the first flat plate portion 21 by cutting and raising the first protrusion 31. In the embodiment, the first hole 41 is a right triangle, and its long side 41b is parallel to the flow direction of the exhaust gas. Of the two short sides of the first hole 41, the short side on the upstream side in the exhaust gas flow direction is indicated by reference numeral 41a, and the short side on the downstream side is indicated by reference numeral 41c.

  The first protrusion 31 is cut and raised from the short side 41c on the downstream side. That is, the first protrusion 31 that has a triangular shape has the first side 31a on the upstream side corresponding to the upstream short side 41a of the first hole 41, and the second side 31b on the downstream side is the first hole. This corresponds to the long side 41 b of the portion 41. The bottom side 31 c of the first protrusion 31 is the downstream short side 41 c of the first hole 41.

  On the other hand, a second hole 42 is formed in the first flat plate portion 21 by cutting and raising the second protrusion 32. In the embodiment, the second hole portion 42 is a right triangle having a congruent shape with the first hole portion 41, and the long side 42b thereof is parallel to the flow direction of the exhaust gas. However, the long side 42 b is located in the left-right opposite direction with respect to the long side 41 b of the first hole portion 41.

  The second protrusion 32 is cut and raised from the downstream side 42c side. That is, the second protrusion 32 having a triangular shape has the first side 32a on the upstream side corresponding to the upstream short side 42a of the second hole part 42, and the second side 32b on the downstream side is the second hole. This corresponds to the long side 42 b of the portion 42. The bottom side of the second protrusion 32 is the downstream short side 42 c of the second hole 42.

  As described above, each of the protrusions 31 and 32 is configured such that the projecting dimension from the first flat plate portion 21 gradually increases toward the upstream side in the exhaust gas flow direction. The first protrusion 31 has an angle θ1 formed by the upstream first side 31a with respect to the first flat plate portion 21 and an angle θ2 formed by the downstream second side 31b with respect to the first flat plate portion 21. (This also applies to the second protrusion 32). Each of the holes 41 and 42 is closed by the tube 2 because the first flat plate portion 21 is in contact with the inner wall of the tube 2.

  A large number of first protrusions 31 and second protrusions 32 are provided, but in the embodiment, the first protrusions 31 and the second protrusions 32 are alternately positioned one by one in the flow direction of the exhaust gas. It is arranged like this. The protrusions 31 and 32 are arranged at intervals in the exhaust gas flow direction, but the arrangement pitch may be constant in the exhaust gas flow direction, but as shown in FIG. It is preferable to set the pitches so that the arrangement intervals become smaller toward the downstream side. That is, since the exhaust gas has a lower temperature and a lower flow rate as it goes downstream, more protrusions 31 and 32 that contact the exhaust gas are secured in order to sufficiently perform heat exchange on the downstream side. Therefore, it is preferable to set the unequal pitch as described above.

  FIG. 8 shows how the exhaust gas flow velocity changes in the exhaust gas flow direction in the vicinity of the wall surface of the first flat plate portion 21 in the configuration as described above. In FIG. 8, the flow velocity of the exhaust gas is divided into four sections 1 to 4 and the average flow velocity for these four sections is shown. In the figure, dots are attached to the comparative example, and as described in Patent Document 1, the protruding dimensions of the cut and raised protrusions are gradually reduced toward the upstream side in the exhaust gas flow direction. (Setting of the protruding dimension in the opposite direction to the present invention). In addition, in the embodiment, hatching indicates that the arrangement pitch of the protrusions 31 and 32 is constant, and the white protrusion indicates the first protrusion 31 corresponding to FIG. The second protrusions 32 are arranged at unequal pitches. The meanings of the above three displays of dots, hatching, and white are the same in the following FIGS. 9 and 10.

  As understood from FIG. 8, in the present invention (hatched display or white display), the change in the flow rate is small between the upstream side and the downstream side as compared with the comparative example, and the flow rate on the downstream side is small. The decrease of the is small. This is preferable in that heat is sufficiently exchanged on the downstream side to improve heat exchange efficiency, and it is also preferable to prevent soot accumulation on the downstream side by suppressing the decrease in the flow velocity on the downstream side as much as possible. It will be a thing.

  FIG. 9 shows the flow velocity in the vicinity of the wall surface at the downstream portion in the exhaust gas flow direction with respect to the right wall surface, the left wall surface, and the opposing wall surface of the first flat plate portion 21. As is clear from FIG. 9, in the present invention, compared to the comparative example, the decrease in the flow velocity is small, and the change in the flow velocity between these three surfaces is small, and the entire wall surface has high heat exchange efficiency. In particular, it is preferable for preventing soot accumulation on the downstream side.

  FIG. 10 shows the variation in the average flow velocity between the three surfaces of the left and right wall surfaces and the opposite wall surface with respect to the first flat plate portion 21 in the downstream portion of the exhaust gas flow direction. In FIG. 10, the case of the comparative example is shown as variation “1”, and the smaller the variation value, the smaller the variation. In the present invention, it is understood that the variation is extremely small such as “0.22” (in the case of equal pitch) and “0.15” (in the case of unequal pitch). In other words, heat exchange can be effectively performed with all the wall surfaces, which is preferable in improving the heat exchange efficiency. In addition, it is preferable to prevent the situation where some of the wall surfaces are likely to accumulate soot.

  Since the first hole 41 and the second hole 42 are located upstream of the first protrusion 31 or the second protrusion 32, that is, the holes 41 and 42 are not connected to the protrusion 31 or 32. Since high-speed exhaust gas before the collision flows, soot accumulation in each of the holes 41 and 42 is not a problem. In the present invention, the decrease in the exhaust gas flow velocity is suppressed on the downstream side of any wall surface. However, this is because the protrusions 31 and 32 are smaller in the protrusion dimension toward the downstream side. This is probably because the flow resistance of the portions 31 and 32 is small. Moreover, it is thought that the variation in the flow velocity between the respective surfaces becomes small because a sufficient flow velocity is secured with respect to the wall surfaces (second flat plate portion 22) on the left and right sides of the protrusions 31 and 32. Further, since the protrusions 31 and 32 have a protrusion dimension that decreases toward the downstream side, the exhaust gas flow velocity in the portion immediately downstream of the protrusions 31 and 32 is increased as much as possible, and the protrusions 31 and 32 are immediately downstream. This is also preferable for preventing soot accumulation in the field.

  Although the embodiment has been described above, the present invention is not limited to the embodiment, and can be appropriately changed within the scope described in the scope of claims. For example, the invention includes the following cases. . The shape of the protrusion formed by cutting and raising is not limited to a triangle, and can be appropriately selected from a quadrangular shape, an irregular shape, and the like. The protruding portions 31 and 32 may include a portion in which the protruding dimension is suddenly reduced on the upstream side in the exhaust gas flow direction from the highest protruding position from the first flat plate portion 21. The heat exchanger H according to the present invention is not limited to an automobile, and can be applied to appropriate uses as long as exhaust gas (fluid containing soot) flows. The arrangement of the first protrusions 31 and the second protrusions 32 in the exhaust gas flow direction is not limited to alternate arrangements, for example, after two first protrusions are arranged in succession, the second protrusions For example, two parts can be arranged in succession. Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

  The present invention can be applied to, for example, an EGR cooler for automobiles.

H: Heat exchanger 1: Outer tube 2: Tube 2a: Inner space 10: Corrugated plate material 21: First flat plate portion 22: Second flat plate portion 31: First protrusion 31a: First side 31b on the upstream side: Downstream side Second side 32: second protrusion 32a: upstream first side 32b: downstream second side 41: first hole 42: second hole

Claims (6)

A heat exchanger for exchanging heat between exhaust gas discharged from an engine and a cooling medium,
A tube having an internal space through which exhaust gas is circulated;
A first flat plate portion that is positioned in the tube and is in contact with the inner wall of the tube; a second flat plate portion that partitions the tube into a plurality of passages;
Have
The first flat plate portion has a surface that is inclined with respect to the flow direction of the exhaust gas by cutting and raising, and a first protrusion portion and a first protrusion portion whose inclination directions with respect to the flow direction of the exhaust gas are set to be opposite to each other. A large number of two protrusions,
Each of the first protrusion and the second protrusion is configured such that the protrusion dimension from the first flat plate portion increases toward the upstream side of the exhaust gas flow direction,
The first protrusion and the second protrusion are formed at different positions in the exhaust gas flow direction.
A heat exchanger characterized by that. In claim 1,
A first hole formed in the first flat plate portion by forming the first protrusion is located upstream of the first protrusion,
A second hole formed in the first flat plate portion by forming the second protrusion is positioned upstream of the second protrusion,
The first hole and the first hole are closed by the inner wall of the tube,
A heat exchanger characterized by that. In claim 1 or claim 2,
Each of the first protrusion and the second protrusion is triangular,
Each of the first protrusions having the triangular shape has an angle θ1 formed by the first side on the upstream side in the exhaust gas flow direction with respect to the bottom side of the first flat plate portion on the downstream side in the exhaust gas flow direction. The second side is made larger than the angle θ2 made with respect to the bottom side of the flat plate portion,
A heat exchanger characterized by that. In any one of Claims 1 thru | or 3,
The heat exchanger according to claim 1, wherein the first protrusions and the second protrusions are formed so as to be alternately positioned in a flow direction of the exhaust gas. In any one of Claims 1 thru | or 4,
The heat exchanger according to claim 1, wherein the first protrusion and the second protrusion are arranged such that an arrangement interval in the exhaust gas flow direction becomes smaller toward the downstream side. In any one of Claims 1 thru | or 5,
The first flat plate portion and the second flat plate portion are integrally formed by a corrugated plate material having a rectangular corrugated shape, and the first flat plate portion is brought into contact with a pair of opposed inner walls of the tube. A heat exchanger characterized by that.

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