JP2013245863A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger capable of improving cooling capability of gas.SOLUTION: A heat exchanger includes a plurality of heat transfer pipes 20, and a pair of end plates 30 supporting both ends of the heat transfer pipes 20, which are encased in a casing. The end plate 30 is configured by laminating metallic thin plates 32, and a plurality of holes penetrated by the heat transfer pipes 20 is bored in the metallic thin plates 32. An interval of adjoining holes in the end plate 30 is narrowed to less than two times the thickness of the end plate 30 in response to a thickness t of the metallic thin plate 32. Accordingly, the cooling capability of gas can be improved by increasing the number of heat transfer pipes 20 to be supported by the end plates 30.

Description

  The present invention relates to a heat exchanger, and more particularly, to a heat exchanger that performs heat exchange between a gas that flows through a plurality of heat transfer pipes and cooling water that flows along the outer surface of each heat transfer pipe. .

  Conventionally, as this type of heat exchanger, there is an EGR cooler applied to an exhaust gas recirculation (EGR) device of a vehicle internal combustion engine, and the EGR cooler is a so-called shell and tube heat exchanger. .

  As an example of an EGR cooler, there is one provided with a plurality of heat transfer pipes, a pair of end plates, and a casing that is open at both ends (see, for example, Patent Document 1).

  The heat transfer pipe has a flat shape with a large aspect ratio of the cross section of the flow path. In the end plate, holes into which the end portions of the heat transfer pipes are inserted are formed so as to penetrate in the thickness direction of the end plate according to the number of heat transfer pipes. These holes are formed in the shape of elongated slits arranged in parallel.

  One end of each heat transfer pipe is inserted into the hole of one end plate. The inner peripheral surface of one end plate hole and the portion of the outer peripheral surface of the heat transfer pipe facing the inner peripheral surface of the end plate hole are joined by brazing over the entire periphery.

  The other end of each heat transfer pipe is inserted into the hole of the other end plate. The inner peripheral surface of the hole of the other end plate and the portion facing the inner peripheral surface of the hole of the end plate on the outer peripheral surface of the heat transfer pipe are joined by brazing over the entire periphery.

  The pair of end plates plays a role of supporting the plurality of heat transfer pipes in parallel, and the plurality of heat transfer pipes and the pair of end plates constitute a core.

  The core is disposed inside the casing, and forms a cooling water passage surrounded by the pair of end plates and the inner surface of the casing.

  The outer edge surface of one end plate and the part facing the outer edge surface of one end plate on the inner surface of the casing are joined by brazing over the entire circumference. The outer edge surface of the other end plate and the portion facing the outer edge surface of the other end plate on the inner surface of the casing are joined by brazing over the entire circumference.

  An exhaust gas inlet for introducing engine exhaust gas from the outside of the casing toward each heat transfer pipe is provided at one end of the casing. The exhaust gas inlet is formed such that the cross section of the flow path gradually expands from the upstream side to the downstream side in the flow direction of the exhaust gas.

  The other end of the casing is provided with an exhaust gas outlet for sending exhaust gas from each heat transfer pipe toward the outside of the casing. The exhaust gas outlet is formed such that the cross section of the flow path gradually decreases from the upstream side to the downstream side in the exhaust gas flow direction.

  The exhaust gas branched from the engine exhaust path flows into the exhaust gas inlet. Exhaust gas flows through the inside of each heat transfer pipe, and is sent to the engine intake path via the exhaust gas outlet. Thereafter, the exhaust gas is mixed with the air sucked from the outside of the engine, and is returned to the inside of the cylinder as intake air.

  A cooling water inlet for introducing cooling water from the outside of the casing to the cooling water passage is provided on the outer side of the other end of the casing. In addition, a cooling water outlet for sending the cooling water from the cooling water passage to the outside of the casing is provided at one end outer side of the casing.

  Cooling water removed by the radiator flows into the cooling water inlet. The cooling water flows through the cooling water passage and is sent to the radiator through the cooling water outlet.

  The heat of the exhaust gas flowing inside each heat transfer pipe is transferred to the cooling water flowing through the cooling water passage through the heat transfer pipe, and thereby the exhaust gas sent from the heat transfer pipe to the engine intake path. The temperature will drop.

JP 2011-185543 A

  In manufacturing the end plate, when the above-described elongated slit-like holes are punched in the metal plate as the material to be processed by press working, the interval between adjacent slit-like holes is, for example, 2 of the thickness of the metal plate. More than double.

  This is because when the distance between the holes narrows to less than twice the thickness of the metal plate, when the punch punches out the metal plate, the portion between the adjacent holes in the end plate is wound into the die, and the opening shape of the hole This is because it is distorted. Thus, when the opening shape of the hole is distorted, there arises a problem that it is difficult to join the inner peripheral surface of the hole and the outer peripheral surface of the heat transfer pipe by brazing.

  For this reason, for example, the interval between adjacent holes in the end plate is set to be twice or more the thickness of the metal plate to prevent distortion of the opening shape of the holes, and the inner peripheral surface of the holes and the outer peripheral surface of the heat transfer pipe are brazed. By attaching, it was possible to be surely joined.

  Therefore, in the conventional EGR cooler in which the interval between adjacent holes in the end plate is restricted as described above, the number of heat transfer pipes supported by the end plate can be increased to improve the exhaust gas cooling performance. There wasn't.

  It is also conceivable to use a thin metal plate as the material to be processed, narrow the gap between adjacent holes in the end plate, and increase the number of heat transfer pipes supported by the end plate. Are securely joined by brazing and the end plate and the casing are securely joined by brazing, the end plate needs to have a predetermined thickness as a brazing allowance. By reducing the thickness of the hole, there is no way to prevent distortion of the opening shape of the hole.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a heat exchanger capable of improving the gas cooling performance.

  In order to solve the above-described problems, a heat exchanger according to the present invention includes (1) a plurality of heat transfer pipes through which gas flows, a pair of end plates that support both ends of the heat transfer pipe, And the heat transfer pipe and the end plate are accommodated in the casing, an outer edge surface of the end plate is joined to an inner side surface of the casing, and the end plate and the casing In the heat exchanger in which a cooling water passage through which cooling water flows is formed by the inner surface of the end plate, the end plate is configured by stacking thin metal plates, and the heat transfer pipe penetrates the thin metal plate. A plurality of holes are formed.

  With this configuration, in the heat exchanger according to the present invention, a plurality of holes through which the heat transfer pipe passes are formed in the metal thin plate, and the metal transfer plate is laminated to form the heat transfer pipe as an end plate. The interval between adjacent holes in the part plate can be reduced according to the thickness of the thin metal plate. Therefore, the number of heat transfer pipes supported by the end plate can be increased, and the gas cooling performance can be improved.

  Moreover, in the heat exchanger according to (1) above, (2) the metal thin plate is integrally fastened by caulking.

  With this configuration, the heat exchanger according to the present invention can easily perform an operation for fastening a plurality of thin metal plates to each other.

  Furthermore, in the heat exchanger according to the above (2), (3) the caulking process is configured by plastically deforming the metal thin plates with each other so that the metal thin plates have an uneven shape in the plate thickness direction. Yes.

  With this configuration, the heat exchanger according to the present invention can securely fasten a plurality of thin metal plates.

  ADVANTAGE OF THE INVENTION According to this invention, the heat exchanger which can improve the cooling performance of gas can be provided.

It is a schematic structure figure showing an EGR cooler concerning an embodiment of the present invention. It is a schematic block diagram which shows the assembly middle of the EGR cooler which concerns on embodiment of this invention. It is a front view of the end plate used for the EGR cooler concerning an embodiment of the present invention. It is sectional drawing of the plastic working part in FIG. It is a partial cutaway view of the core in the EGR cooler according to the embodiment of the present invention. FIG. 6 is a partial cutaway view of the core when FIG. 5 is viewed in the A direction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 show a case where a heat exchanger according to the present invention is applied to an EGR cooler 10 in an EGR device for a vehicle internal combustion engine. The EGR cooler 10 includes a plurality of heat transfer pipes 20 and a pair of ends. A part plate 30 and a casing 40 having both ends opened are provided.

  The heat transfer pipe 20 is made of metal and has a flat shape with a large aspect ratio of the cross section of the flow path, as shown in FIGS. The end plate 30 is made of metal, and is constituted by a disk-shaped thin metal plate 32 shown in FIG. The casing 40 is made of metal and is a hollow structure having a circular cross section, and accommodates the heat transfer pipe 20 and the end plate 30. As shown in FIGS. 1 and 2, plastic processing is performed on both ends of the casing 40.

  In the end plate 30, holes 31 into which the end portions of the heat transfer pipes 20 are inserted are formed so as to penetrate in the thickness direction of the end plate 30 according to the number of the heat transfer pipes 20. These holes 31 are formed in the shape of elongated slits arranged in parallel.

  One end of each heat transfer pipe 20 is inserted into the hole 31 of one end plate 30. The inner peripheral surface of the hole 31 of one end plate 30 and the portion facing the inner peripheral surface of the hole 31 of the end plate 30 on the outer peripheral surface of the heat transfer pipe 20 are joined by brazing over the entire periphery. Yes.

  The other end of each heat transfer pipe 20 is inserted into the hole 31 of the other end plate 30. The inner peripheral surface of the hole 31 of the other end plate 30 and the portion facing the inner peripheral surface of the hole 31 of the end plate 30 on the outer peripheral surface of the heat transfer pipe 20 are joined by brazing over the entire periphery. Yes.

  The pair of end plates 30 play a role of supporting the plurality of heat transfer pipes 20 in parallel, and the plurality of heat transfer pipes 20 and the pair of end plates 30 constitute a core 50.

  The core 50 is disposed inside the casing 40, and forms a cooling water passage 60 surrounded by the pair of end plates 30 and the inner side surface of the casing 40.

  The outer edge surface of one end plate 30 and the portion facing the outer edge surface of one end plate 30 on the inner side surface of the casing 40 are joined by brazing over the entire circumference. The outer edge surface of the other end plate 30 and the portion facing the outer edge surface of the other end plate 30 on the inner side surface of the casing 40 are joined to each other by brazing.

  An exhaust gas inlet 41 for introducing engine exhaust gas G from the outside of the casing 40 toward the heat transfer pipes 20 is provided at one end of the casing 40. The exhaust gas inlet 41 is, for example, a cross-section of the flow path integrally with the casing 40 and from the upstream side to the downstream side in the flow direction of the exhaust gas G by spinning or the like, which is a well-known plastic processing method as described later. Is formed to gradually expand.

  At the other end of the casing 40, an exhaust gas outlet 42 for sending the exhaust gas G from each heat transfer pipe 20 toward the outside of the casing 40 is provided. The exhaust gas outlet 42 is formed so as to be gradually reduced from the upstream side to the downstream side in the flow direction of the exhaust gas G integrally with the casing 40 by spinning or the like, similar to the exhaust gas inlet 41. Has been.

  Exhaust gas G diverted from the engine exhaust path flows into the exhaust gas inlet 41. The exhaust gas G flows through each heat transfer pipe 20 and is sent to the engine intake path via the exhaust gas outlet 42. Thereafter, the exhaust gas G is mixed with the air sucked from the outside of the engine, and is returned to the inside of the cylinder as intake air.

  A cooling water inlet 43 for introducing the cooling water W from the outside of the casing 40 to the cooling water passage 60 is provided on the outer side of the other end of the casing 40. A cooling water outlet 44 for sending the cooling water W to the outside of the casing 40 is provided.

  The cooling water inlet 43 and the cooling water outlet 44 are cylindrical metal members, and are inserted into holes formed in the other end outer side and one end outer side of the casing 40. The cooling water inlet 43 and the cooling water outlet 44 are joined to the casing 40 by brazing.

  The cooling water removed from the radiator flows into the cooling water inlet 43. The cooling water W flows through the cooling water passage 60 and is sent to the radiator via the cooling water outlet 44.

  The heat of the exhaust gas G flowing inside each heat transfer pipe 20 is transmitted to the cooling water W flowing through the cooling water passage 60 via the heat transfer pipe 20, and thereby, from the heat transfer pipe 20 to the engine intake path. The temperature of the exhaust gas G to be delivered will drop.

  The characteristic part of the EGR cooler 10 according to the present embodiment focuses on the relationship between the distance between adjacent holes and the thickness of the metal plate when a plurality of holes are drilled in the metal plate that is the material to be processed. The end plate 30 is configured by laminating and fastening the thin metal plates 32.

  The thin metal plate 32 is formed in a disc shape so as to fit coaxially inside the casing 40. Holes 31 into which the end portions of the heat transfer pipes 20 are inserted are formed in the metal thin plate 32 so as to penetrate in the thickness direction of the metal thin plate 32 according to the number of the heat transfer pipes 20. Since the metal thin plate 32 is a constituent member of the end plate 30, these holes 31 are formed in the shape of elongated slits arranged in parallel.

  The end plate 30 is formed by laminating a plurality of thin metal plates 32. The holes 31 in each end plate 30 overlap at the same position. Further, the laminated metal thin plates 32 are integrally fastened by a plurality of plastic working portions 33. The plastic working parts 33 are located at equal intervals in the circumferential direction of the end plate 30.

  The plastic working portion 33 is formed by subjecting the laminated metal thin plates 32 to a process (caulking) that plastically deforms a predetermined portion of each metal thin plate 32 in the plate thickness direction. The plastic working portion 33 is obtained by plastically deforming the metal thin plates 32 so that the metal thin plates 32 are uneven in the thickness direction. The adjacent thin metal plates 32 are fixed by the frictional force generated between the thin metal plates 32 in the plastic working portion 33.

  Therefore, paying attention to the individual thin metal plates 32, one end of the heat transfer pipe 20 is inserted into each hole 31 of the thin metal plate 32, and the inner peripheral surface of the hole 31 of the thin metal plate 32 and the heat transfer pipe. The portion of the outer peripheral surface 20 facing the inner peripheral surface of the hole 31 of the thin metal plate 32 is joined by brazing over the entire periphery. Further, the outer edge surface of the thin metal plate 32 and the portion facing the outer edge surface of the end plate 30 on the inner side surface of the casing 40 are joined by brazing over the entire circumference.

  In the metal thin plate 32, the interval d between adjacent slit-shaped holes 31 is set to be twice or more the thickness t of the metal thin plate 32. As described above, when the distance d between the holes 31 is less than twice the thickness t of the thin metal plate 32, the portion between the adjacent holes 31 in the thin metal plate 32 when the punch punches the thin metal plate 32. This is because the opening shape of the hole 31 is distorted.

  In the EGR cooler 10 according to the present embodiment, for example, the end plate 30 and the heat transfer pipe 20 are securely joined by brazing, and the end plate 30 and the casing 40 are securely joined by brazing. If the brazing allowance required for this is 3 mm, the brazing allowance, that is, the end plate 30 having a thickness of 3 mm, is obtained by stacking and fastening five metal thin plates 32 having a thickness t of 0.6 mm. Is obtained.

  In the thin metal plate 32 having a thickness t of 0.6 mm, when the distance d between adjacent holes 31 is set to be twice the thickness t so that the opening shape of the slit-shaped holes 31 is not distorted, the distance d is 1.2 mm. become. Therefore, when the end plate 30 is viewed as a whole, the distance d between the slit-shaped holes 31 is less than twice the thickness of the end plate 30.

  Further, when two metal thin plates 32 having a thickness t of 1.5 mm are stacked and fastened to obtain an end plate 30 having a thickness of 3 mm, the distance d between adjacent holes 31 is set to be twice the thickness t. For example, the distance d is 3 mm, which is twice the thickness of the end plate 30.

  Furthermore, when ten metal thin plates 32 having a thickness t of 0.3 mm are stacked and fastened to obtain an end plate 30 having a thickness of 3 mm, the distance d between adjacent holes 31 is set to be twice the thickness t. For example, the distance d is 0.6 mm, which is less than twice the thickness of the end plate 30.

  On the other hand, when a plurality of holes penetrating in the thickness direction of the metal plate are drilled in a metal plate having a thickness of 3 mm, in order to prevent the opening shape of the holes from being distorted, the interval between adjacent holes is set to The thickness of the metal plate needs to be twice or more, that is, 6 mm or more.

  Thus, according to the EGR cooler 10 according to the present embodiment, the distance d between the adjacent holes 31 in the end plate 30 is less than twice the thickness of the end plate 30 according to the thickness t of the thin metal plate 32. Can be narrowed. Therefore, the number of heat transfer pipes 20 supported by the end plate 30 can be increased, and the cooling performance of the exhaust gas G can be improved.

  Next, an assembly procedure of the EGR cooler 10 according to this embodiment will be described.

  A straight tubular casing 40 is prepared, and one end of the casing 40 is subjected to a spinning process, which is a well-known plastic process, to integrally form an exhaust gas inlet 41. 1 and 2, a portion illustrated by a two-dot chain line at the left end portion of the EGR cooler 10 represents one end portion of the casing 40 before the spinning process is performed.

  Specifically, a plurality of spinning rollers (not shown) that revolve relative to the casing 40 are pressed against one end of the casing 40 while simultaneously moving in the axial direction and the radial direction of the casing 40, A rotationally symmetrical exhaust gas inlet 41 having a predetermined contour is formed.

  In performing the spinning process, a method of fixing the casing 40 and revolving the spinning roller with respect to the casing 40, a method of rotating the casing 40 in the circumferential direction without revolving the spinning roller, or A method of rotating the casing 40 in the circumferential direction and revolving the spinning roller with respect to the casing 40 can be appropriately selected.

  Further, a hole for inserting the cooling water inlet 43 is formed in the outer side of the other end of the casing 40, and a hole for inserting the cooling water outlet 44 is formed in the outer side of the one end of the casing 40.

  A plurality of thin metal plates 32 are stacked, and the thin metal plates 32 are fastened by a plastic working portion 33 to constitute each of the pair of end plates 30. Then, one end of each heat transfer pipe 20 is inserted into the hole 31 of one end plate 30, and the other end of each heat transfer pipe 20 is inserted into the hole 31 of the other end plate 30. Thus, the core 50 is configured by the plurality of heat transfer pipes 20 and the pair of end plates 30.

  When the core 50 is configured, brazing is performed between the inner peripheral surface of the hole 31 of each end plate 30 and the portion of the outer peripheral surface of the heat transfer pipe 20 facing the inner peripheral surface of the hole 31 of the end plate 30. The filler metal for use is interposed. As the filler metal, for example, there is a paste-like material in which a binder mainly composed of a solvent or the like and a metal powder as a brazing material are mixed.

  Further, as shown in FIG. 2, the core 50 is inserted into the casing 40 from the other end of the casing 40, that is, from the right end side of the EGR cooler 10. At this time, a filler metal for brazing is interposed between the outer edge surface of the end plate 30 and a portion facing the outer edge surface of the end plate 30 on the inner side surface of the casing 40.

  The cooling water inlet 43 and the cooling water outlet 44 are inserted into holes formed in the other end outer side and one end of the casing 40. At this time, between the inner peripheral surface of each hole drilled in the outer portion of the casing 40 and the portion facing the inner peripheral surface of each hole of the casing 40 on the outer peripheral surface of the cooling water inlet 43 and the cooling water outlet 44, A filler metal for brazing is interposed.

  Then, the casing 40 in which the core 50, the cooling water inlet 43 and the cooling water outlet 44 are assembled is sealed in a heating furnace, and the inside of the heating furnace is filled with a predetermined atmospheric gas, and then the casing 40, the core 50, and the cooling water inlet 43 And the cooling water outlet 44 is generally heated to melt the filler metal.

  If the filler metal is melted, the filler metal is solidified when the heating is stopped and the casing 40, the core 50, the cooling water inlet 43 and the cooling water outlet 44 are naturally cooled. As a result, the heat transfer pipe 20 and the end plate 30 are joined, the end plate 30 and the casing 40 are joined, and the cooling water inlet 43 and the cooling water outlet 44 are joined to the casing 40.

  Thereafter, the other end portion of the casing 40 is subjected to a spinning process in the same manner as the one end portion of the casing 40 to integrally form the exhaust gas outlet 42 described above, thereby establishing the EGR cooler 10. In FIG. 1, a portion indicated by a two-dot chain line at the right end portion of the EGR cooler 10 represents the other end portion of the casing 40 before the spinning process is performed.

  In the EGR cooler 10 according to this embodiment, the casing 40 is formed by spinning a metal cylinder. However, the casing 40 may be manufactured by pressing a metal plate. Moreover, you may make it produce the casing 40 by casting methods, such as die-casting.

  The cross-sectional shape of the casing 40 is not limited to a circular shape, and may be a rectangular shape, for example. When the cross-sectional shape of the casing 40 is a non-circular shape such as a rectangle, the shape of the end plate 30 is made to match the cross-sectional shape of the casing 40.

  In the EGR cooler 10 according to the present embodiment, the exhaust gas inlet 41 and the exhaust gas outlet 42 are formed integrally with the casing 40, but the exhaust gas inlet 41 and the exhaust gas outlet 42 are separately manufactured, and You may make it join.

  In the EGR cooler 10 according to the present embodiment, the cross section of the flow path of the heat transfer pipe 20 has a flat shape, but the heat transfer pipe 20 may be a normal pipe material. When a normal pipe material is used for the heat transfer pipe 20, the shape of the hole 31 of the end plate 30 is circular.

  Further, the cross-sectional shape of the flow path of the heat transfer pipe 20, the number of heat transfer pipes 20, and the cross-sectional shape of the casing 40 are appropriately selected according to design specifications such as heat exchange capacity.

  Furthermore, even when the flow path cross-sectional shape of the heat transfer pipe 20, the number of heat transfer pipes 20, and the cross-sectional shape of the casing 40 are changed, the distance d between the adjacent holes 31 in the end plate 30 is set to the thickness of the metal thin plate 32. Depending on t, narrowing to less than twice the thickness of the end plate 30 can be achieved. Therefore, the cooling performance of the exhaust gas G can be improved by increasing the number of heat transfer pipes 20 supported by the end plate 30 as in the present embodiment.

  As described above, the present invention has an effect of providing a heat exchanger capable of improving the gas cooling performance, and is an EGR applied to an EGR device in a vehicle internal combustion engine. Useful as a cooler.

10 EGR cooler 20 Heat transfer pipe 30 End plate 31 Hole 33 Plastic working part 40 Casing 60 Cooling water passage G Exhaust gas W Cooling water

Claims (3)

A plurality of heat transfer pipes through which gas flows;
A pair of end plates that support both ends of the heat transfer pipe;
A casing with both ends open,
The heat transfer pipe and the end plate are accommodated in the casing, the outer edge surface of the end plate is joined to the inner side surface of the casing, and the end plate and the inner side surface of the casing provide cooling water. In a heat exchanger that forms a cooling water passage through which
The end plate is configured by laminating thin metal plates,
The metal thin plate is provided with a plurality of holes through which the heat transfer pipe penetrates.   The heat exchanger according to claim 1, wherein the metal thin plates are integrally fastened by caulking.   3. The heat exchanger according to claim 2, wherein the caulking process is configured by plastically deforming the metal thin plates so that the metal thin plates have an uneven shape in a plate thickness direction.

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