JP6024568B2 - Heat exchanger - Google Patents

Description

  The present invention relates to a heat exchanger in which heat exchange is performed between a fluid flowing in a flat pipe and a fluid flowing outside thereof.

  Patent Document 1 discloses an example of a heat exchanger that cools exhaust gas generated in a combustion chamber by heat exchange with cooling water and recirculates the exhaust gas to an intake system. Such a heat exchanger includes a casing in which cooling water circulates and a plurality of pipes arranged in the casing. Each pipe has a dimension in the width direction that is larger than a dimension in the thickness direction orthogonal to the width direction, and is flat. In the casing, the flat pipes are arranged in the thickness direction, and the exhaust gas flows through the pipes.

  The upstream end and the downstream end of each pipe are provided with an expanded portion having a larger dimension in the thickness direction than the passage portion located between the upstream end and the downstream end. The expansion part is in contact with the expansion part of another adjacent pipe. On the other hand, the passage portion positioned between the upstream end expansion portion and the downstream end expansion portion is not in contact with the passage portions of other adjacent pipes, and cooling water is provided between the adjacent passage portions. Is flowing. The exhaust gas is cooled by heat exchange between the cooling water and the exhaust gas flowing in each pipe.

JP 2011-112331 A

  When exhaust flows inside the pipe, the pressure inside the pipe may be higher than the pressure outside the pipe due to the pressure of the exhaust. In this case, as shown in FIG. 9, a force F <b> 1 is exerted on the side wall of the pipe 100 having a substantially quadrangular ring shape in cross section so as to push the side wall outward. Further, as shown in FIG. 9, when the four corner portions where the pipe wall of the pipe 100 is bent from the thickness direction to the width direction are used as the corner portions 130, the corner portions 130 are developed on the corner portions 130. The force F2 to be applied acts. As a result, stress concentration due to the force F2 is likely to occur in the corner portion 130.

  In addition, since the expansion part of the piping 100 is in contact with the expansion part of other piping, it is difficult to expand, and the said force F2 does not act easily on the corner part of the expansion part. On the other hand, the passage portion located between the upstream end expanding portion and the downstream end expanding portion is not in contact with other pipes, and therefore is easily expanded by the exhaust pressure compared to the expanding portion, Stress concentration is likely to occur due to the force F2 trying to expand the corner portion.

  The objective of this invention is providing the heat exchanger which can suppress that stress concentrates on the specific location of the piping, when a fluid flows through the inside of flat piping.

  A heat exchanger for solving the above-described problems has a passage portion and an expanded portion that is larger in the thickness direction than the passage portion and communicates with the passage portion, and is orthogonal to the thickness direction. A plurality of flat pipes whose dimensions in the width direction are larger than the dimensions in the thickness direction are arranged in the casing in a manner of being arranged in the thickness direction. Further, in this heat exchanger, the expanding portions adjacent to each other in the thickness direction are in contact with each other, while the passage portions adjacent to each other in the thickness direction are not in contact with each other, and the fluid flowing in the pipe And heat exchange between the fluid flowing between the passage portions. And in this heat exchanger, the direction perpendicular to both the width direction and the thickness direction is the length direction, and the section where the pipe wall of the pipe is bent in the cross section perpendicular to the length direction is a corner. When it is set as a part, the curvature radius of the corner part of a channel | path part is larger than the curvature radius of the corner part of an expansion part.

  At the corner portion of the pipe, a force is exerted to expand the corner portion by expanding the side wall of the pipe due to the pressure of the fluid flowing in the pipe. Here, the greater the radius of curvature of the corner portion, the more widely the stress acting on the corner portion when the force for expanding the corner portion is applied. Therefore, in the above configuration, the radius of curvature of the corner portion of the passage portion is made larger than the radius of curvature of the corner portion of the expanded portion. Thereby, compared with the case where the curvature radius of the corner part of a channel | path part is the same as the curvature radius of the corner part of an expansion part, it becomes difficult to produce stress concentration in the corner part of a channel | path part. Therefore, when a fluid flows through the inside of a flat pipe, it can suppress that stress concentrates on the specific location of the pipe.

In the heat exchanger, it is possible to provide the expanded portions at both ends in the length direction of the pipe.
In addition, when the pipe located on the outermost side in the thickness direction in which the pipes are arranged is the outermost pipe, the expanded part of the outermost pipe is added to the expanded part of the other adjacent pipes, It is preferable to contact also the side wall of the casing. According to this configuration, the outermost pipe can be supported by the casing, and each pipe can be supported more firmly.

  And you may make it fill the clearance gap surrounded by the corner part of each adjacent expansion part, and the side wall of a casing with a bonding agent. According to this configuration, since the radius of curvature of the corner portion of the expanded portion is smaller than the radius of curvature of the corner portion of the passage portion, the amount of the bonding agent used to fill the gap is small because the gap is narrow. Tesumu. Further, according to the configuration in which the outermost pipe is also brought into contact with the casing as described above, even if the expansion portion of the outermost pipe is expanded due to an increase in pressure in the outermost pipe, the expansion of other pipes is increased. The expansion of the expanded portion of the outermost pipe can be regulated by the side wall of the portion or the casing. Moreover, since the expansion part of the pipe inside the outermost pipe is in contact with the expansion part of the pipe located on both sides of the pipe, the expansion of the expansion part is restricted. For this reason, even when the radius of curvature of the corner portion of the expanded portion is made smaller than the radius of curvature of the corner portion of the passage portion as described above and the amount of bonding agent used is suppressed, the corner portion of the expanded portion It becomes possible to suppress stress concentration on the surface.

  Furthermore, it is preferable that a gap is provided between the passage portion of the outermost pipe and the side wall of the casing. According to this configuration, the heat exchange fluid can be interposed in the gap provided between the passage portion of the outermost pipe and the side wall of the casing, and between the fluid flowing in the outermost pipe. Effective heat exchange can be achieved.

  The heat exchanger is attached to a part of the exhaust gas recirculation passage for recirculating the exhaust gas of the internal combustion engine to the intake system, and performs heat exchange between the exhaust gas flowing in the piping and the cooling water flowing outside the piping in the casing. It can be applied as a so-called cooler.

The perspective view which shows typically one Embodiment of a heat exchanger. The exploded perspective view of the heat exchanger. Sectional drawing which shows a part of internal structure of the heat exchanger. The top view which shows the state in which the some piping is located in a line in the casing in the heat exchanger. (A) is sectional drawing at the time of cut | disconnecting the same heat exchanger by the 5-5 line in FIG. 4, (b) is sectional drawing to which a part of FIG. 5 (a) was expanded. (A) is sectional drawing at the time of cut | disconnecting the same heat exchanger by the 6-6 line in FIG. 4, (b) is sectional drawing to which a part of FIG. 6 (a) was expanded. The graph which shows the relationship between the curvature radius of a corner part, and the stress concentration degree to the corner part. (A) is sectional drawing which shows the heat exchanger of another embodiment, (b) is sectional drawing to which a part of FIG. 8 (a) was expanded. The action figure which shows the state in which the force is acting on the corner part of piping of the conventional heat exchanger.

Hereinafter, an embodiment in which the heat exchanger is embodied as a heat exchanger of an internal combustion engine that cools exhaust gas recirculated to an intake system will be described with reference to FIGS.
The heat exchanger 11 shown in FIG. 1 is arranged in the middle of a recirculation path for recirculating exhaust gas as EGR gas to the intake system, and has a function of cooling the EGR gas flowing in the heat exchanger 11. EGR cooler. EGR is an abbreviation for “Exhaust Gas Recirculation”.

  As shown in FIG. 1, the casing 20 of the heat exchanger 11 includes a case main body 22, a fixing member 23, a first lid body 25, and a second lid body 26. The fixing member 23 includes a cooling water inflow portion 231 that allows cooling water as an example of a heat exchange fluid to flow into the casing 20, and a cooling water outflow portion 232 that causes the cooling water circulated through the casing 20 to flow outside. Is provided. Further, the first lid 25 is provided with a gas inflow portion 251 for allowing EGR gas to flow into the casing 20, and the second lid 26 has a gas outflow for allowing the EGR gas flowing through the casing 20 to flow outside. A portion 261 is provided.

  As shown in FIG. 2, the case body 22 is configured in a substantially U shape. That is, the case main body 22 includes a base portion 221 that faces the fixing member 23 and a pair of side wall portions 222 that are erected on both sides of the base portion 221. And the fixing member 23 is fixed to the front-end | tip of a pair of side wall part 222, and the cylindrical body 21 which makes a substantially square cylinder shape is comprised. The opening at one end of the cylindrical body 21 is closed by the first lid body 25, and the opening at the other end of the cylindrical body 21 is closed by the second lid body 26.

  The casing 20 accommodates a plurality of flat (here, five) pipes 30 in which the dimension L1 in the width direction is larger than the dimension L2 in the thickness direction orthogonal to the width direction. The pipe 30 is configured by bending a single plate material. The pipes 30 are arranged in the casing 20 in such a manner that the length directions perpendicular to both the thickness direction and the width direction coincide with the length direction of the cylindrical body 21 while being arranged in the thickness direction. Has been.

  Then, the EGR gas that has flowed into the casing 20 through the gas inflow portion 251 of the first lid body 25 is diverted before the pipes 30 and flows into the pipes 30. Further, the EGR gas that has flowed through the pipes 30 flows out of the pipes 30, joins, and flows out of the casing 20 through the gas outflow portion 261 of the second lid 26.

  As shown in FIG. 3, among the end portions in the length direction of the base portion 221 of the case main body 22 constituting the casing 20, the end portion on the side where the first lid body 25 is fixed is referred to as “upstream end portion 221 </ b> A”. The end portion on the side where the second lid body 26 is fixed is referred to as a “downstream end portion 221B”. A portion between the upstream end portion 221A and the downstream end portion 221B is referred to as a “center portion 221C”. The base portion 221 is formed with a recess so that the central portion 221C is positioned outside the upstream end portion 221A and the downstream end portion 221B. On the other hand, the pipe 30 is in contact with the upstream end portion 221A and the downstream end portion 221B of the base portion 221 of the case main body 22, but is not in contact with the central portion 221C. And cooling water flows through the space SP1 formed between each pipe 30 and the central portion 221C.

  As shown in FIG. 4, the upstream end and the downstream end of the pipe 30 are provided with an expanded portion 31 having a dimension larger in the thickness direction than the passage portion 32 between the upstream end and the downstream end. The inside of the expanding portion 31 communicates with the inside of the passage portion 32, and the EGR gas flowing into the casing 20 from the gas inflow portion 251 and flowing in the expanding portion 31 at the upstream end flows in the passage portion 32. Flows into the expanded portion 31 at the downstream end, flows out of the pipe 30 from the expanded portion 31, and flows out of the casing 20 through the gas outflow portion 261.

  As shown in FIG. 5A, the expanded portion 31 of the pipe 30 is in contact with the expanded portion 31 of the adjacent pipe 30. Further, both side walls in the width direction of the expanding portion 31 are in contact with the fixing member 23 and the base portion 221 of the case main body 22. Further, the expanded portion 31 of the outermost pipe 30 </ b> A located on the outermost side of the pipe 30 is connected to the expanded portion 31, the fixing member 23, and the base 221 of the case body 22 positioned on the inner side of the outermost pipe 30 </ b> A. In addition, it is in contact with the side wall 222 of the case body 22. That is, each piping 30 is supported by the casing 20 at their upstream end and downstream end.

  As shown in FIG. 5B, when the four corners bent in the widened portion 31 having a substantially quadrangular ring shape in cross section are defined as “corner portions 311”, the radius of curvature of the corner portions 311 is relatively The first curvature radius R1 is small. Therefore, the gap SP <b> 2 formed between each of the adjacent expanded portions 31 and the side wall of the casing 20 is very narrow. The gap SP2 is filled with wax as a bonding agent so as to fill the gap SP2.

  As shown in FIG. 6A, the passage portion 32 of the pipe 30 is not in contact with another adjacent pipe 30. Further, the passage portion 32 of the outermost pipe 30 </ b> A does not contact the side wall portion 222 of the case body 22. The cooling water flows through the gap SP3 formed between the passage portions 32 and between the passage portion 32 of the outermost pipe 30A and the side wall portion 222 of the case body 22. Further, as shown in FIG. 6B, when the four corners bent in the passage portion 32 having a substantially quadrangular annular shape in cross section are defined as “corner portions 321”, the radius of curvature of the corner portion 321 is the expanded portion. The second radius of curvature R2 is larger than the first radius of curvature R1, which is the radius of curvature of the 31 corner portion 311.

Next, with reference to FIG. 7, the effect | action of the heat exchanger 11 of this embodiment is demonstrated.
When EGR gas is flowing in each pipe 30 of the heat exchanger 11, the pressure inside the pipe 30 becomes higher than the pressure outside the pipe 30 due to the pressure of the EGR gas, and the pipe 30 tends to expand outward. . At this time, since the passage portion 32 of the pipe 30 is not in contact with the other adjacent pipe 30 or the side wall portion 222 of the case body 22 of the casing 20, the passage portion 32 easily expands outward. Therefore, a force for expanding the corner portion 321 is likely to act on the corner portion 321 of the passage portion 32.

  On the other hand, since the expansion part 31 of the piping 30 is in contact with the expansion part 31 and the casing 20 of the other adjacent pipes 30, the expansion of the expansion part 31 is restricted. As a result, it is difficult for a force to unfold the corner portion 311 to act on the corner portion 311 of the expanding portion 31.

  Here, FIG. 7 shows a graph showing the relationship between the radius of curvature of the corner portion and the stress concentration degree. As shown in FIG. 7, under the condition that the thicknesses of the plate members constituting the pipe are equal, the stress concentration degree decreases as the radius of curvature of the corner portion increases.

  In the heat exchanger 11 of the present embodiment, the radius of curvature (R2) of the corner portion 321 of the passage portion 32 is larger than the radius of curvature (R1) of the corner portion 311 of the expanded portion 31. Therefore, even if it is the corner part 321 of the channel | path part 32 where a force tends to act, the stress concentration to the corner part 321 is suppressed.

According to the above configuration and operation, the following effects can be obtained.
(1) The radius of curvature of the corner portion 321 of the passage portion 32 is made larger than the radius of curvature of the corner portion 311 of the expanded portion 31. Thereby, compared with the case where the curvature radius of the corner part 321 of the channel | path part 32 is the same as the curvature radius of the corner part 311 of the expansion part 31, it becomes difficult to produce stress concentration in the corner part 321 of the channel | path part 32. . Therefore, when EGR gas flows through the flat pipe 30, it is possible to suppress stress concentration at a specific location of the pipe 30.

(2) Since the expanded portion 31 provided at the upstream end and the downstream end of the outermost pipe 30A is supported by the casing 20, each pipe 30 can be supported more firmly.
(3) Further, since the radius of curvature of the corner portion 311 of the expanded portion 31 is made smaller than the radius of curvature of the corner portion 321 of the passage portion 32, the gap SP2 between the expanded portions 31 becomes narrower. The amount of wax used to fill SP2 can be reduced.

  Moreover, the process which fills the said clearance gap SP2 with a soot (wax) may be performed in the furnace for a soot (brazing). In this case, since the wrinkles can be held by the surface tension generated at each corner portion 311 surrounding the gap SP2, the gap SP2 can be reliably filled with a small amount of wrinkles.

  (4) Since the adjacent passage portions 32 are separated from each other, the cooling water can flow between the respective passage portions 32. Further, since the passage portion 32 of the outermost pipe 30 </ b> A is not in contact with the side wall portion 222 of the casing 20, the cooling water can also flow between the passage portion 32 and the side wall portion 222 of the outermost pipe 30 </ b> A. . Therefore, the EGR gas flowing through the passage portion 32 of the pipe 30 can be efficiently cooled.

  (5) The adjacent expanded parts 31 are in contact with each other, and the expanded part 31 of the outermost pipe 30A is in addition to the expanded part 31 of the pipe 30 located inside the outermost pipe 30A. The side wall 222 is also in contact with the other side wall 222. Therefore, even if the expanded portion 31 tries to expand due to an increase in pressure in the piping 30, the expansion of the expanded portion 31 can be regulated by the expanded portion 31 of the other piping 30 or the side wall portion 222 of the casing 20. Therefore, even if the radius of curvature of the corner portion 311 of the expanded portion 31 is smaller than the radius of curvature of the corner portion 321 of the passage portion 32, stress concentration on the corner portion 311 of the expanded portion 31 can be suppressed. .

The above embodiment may be changed to another embodiment as described below.
-Since hot EGR gas will flow in the piping 30, the temperature of the piping 30 also rises. Therefore, the bonding agent filled in the gap SP2 formed between the corner portions 311 of the expanded portions 31 of the pipes 30 adjacent to each other has a melting point higher than the assumed upper temperature limit of the pipe 30. There is a need to. However, a bonding agent other than brazing may be used as long as it has a melting point higher than the assumed upper temperature limit of the pipe 30.

  -The piping 30 may be the structure which provided the expansion part 31 in arbitrary places other than the upstream end and downstream end. For example, you may provide the expansion part 31 in the center in the length direction of the piping 30. FIG. In this case, the passage portion 32 is provided on the upstream side and the downstream side of the expanding portion 31.

  The expanded portion 31 of the outermost pipe 30 </ b> A may not be in contact with the side wall portion 222 of the case body 22 of the casing 20. In this case, each pipe 30 may be supported by the casing 20 by separately interposing a support member between the expanded portion 31 and the side wall portion 222.

  -The channel | path part 32 of the piping 30 may be the structure which provided the protrusion or rib which protrudes outside from the side wall. In this case, the expansion of the passage portion 32 can be suppressed by such protrusions or ribs coming into contact with other adjacent pipes 30.

  In order to suppress stress concentration at a specific location in the passage portion 32 of the pipe 30, it is preferable to increase the radius of curvature of the corner portion 321 of the passage portion 32 as much as possible. For example, as shown in FIGS. 8A and 8B, when the dimension in the thickness direction of the passage portion 32 is “T” and the radius of curvature of the corner portion 321 is “R”, R = T / 2 The corner portion 321 may be formed so that the above relationship is established. In this case, two corner portions 321 arranged in the thickness direction in one passage portion 32 are smoothly connected, and both ends of the passage portion 32 in the width direction are arcuate.

  -The fluid circulating outside the pipe 30 in the casing 20 is a fluid other than cooling water such as a gas such as air or oil if the cooling efficiency of the EGR gas flowing in the pipe 30 can be sufficiently secured. It may be.

  -If the cross-sectional shape when the pipe 30 is cut in a direction perpendicular to the length direction is a polygonal ring shape, the pipe 30 has a shape other than the substantially quadrangular ring shape in cross section, such as the substantially triangular ring shape in cross section. May be.

  -Although the heat exchanger which cools EGR gas was illustrated as an example which embodied heat exchanger, if it is a heat exchanger with which heat exchange is performed between the fluid which flows through flat piping, and the fluid which flows the outside By applying the same configuration as that of the heat exchanger, stress concentration on the piping can be suppressed. For example, the configuration of this heat exchanger can be applied to an intercooler that cools intake air in a supercharged internal combustion engine.

The fluid flowing through the pipe is not limited to gas but may be liquid, or the fluid flowing outside the pipe may be gas.
An example of the heat exchanger that functions as a cooler that cools the fluid flowing in the pipe with the fluid as the refrigerant flowing outside the pipe is illustrated. On the other hand, the configuration of this heat exchanger is a heat exchanger that functions as a heat accumulator as long as it exchanges heat between the fluid flowing in the pipe and the fluid flowing outside the pipe, The present invention can also be applied to a heat exchanger that functions as a heater that warms a flowing fluid with a fluid flowing outside a pipe.

  DESCRIPTION OF SYMBOLS 11 ... Heat exchanger, 20 ... Casing, 222 ... Side wall part as side wall of casing, 30 ... Piping, 30A ... Outermost piping, 31 ... Expansion part, 311 ... Corner part of expansion part, 32 ... Passage part, 321 ... Corner portion of passage, SP2 ... gap.

Claims (6)

A passage portion and an expanded portion having a larger dimension in the thickness direction than the passage portion and communicating with the passage portion, and a dimension in a width direction perpendicular to the thickness direction is larger than a dimension in the thickness direction. A plurality of large flat pipes are arranged in the casing in a manner aligned in the thickness direction,
While the expanding portions adjacent to each other in the thickness direction are in contact with each other, the passage portions adjacent to each other in the thickness direction are not in contact with each other, and the fluid flowing in the pipe and the passage portions are in contact with each other. In a heat exchanger that exchanges heat with a fluid flowing between
When the direction perpendicular to both the width direction and the thickness direction is the length direction, and the portion where the pipe wall of the pipe is bent in the cross section perpendicular to the length direction is a corner portion,
A heat exchanger, wherein a radius of curvature of a corner portion of the passage portion is larger than a radius of curvature of a corner portion of the spread portion. The heat exchanger according to claim 1, wherein the expansion portions are provided at both ends of the pipe in the length direction. Among the pipes, when the pipe located on the outermost side in the thickness direction in which the pipes are lined is the outermost pipe,
The heat exchanger according to claim 1, wherein an expanded portion of the outermost pipe is in contact with a side wall of the casing. The heat exchanger according to claim 3, wherein a gap surrounded by a corner portion of each of the expanded portions adjacent to each other and a side wall of the casing is filled with a bonding agent. Among the pipes, when the pipe located on the outermost side in the thickness direction in which the pipes are lined is the outermost pipe,
The heat exchanger as described in any one of Claims 1-4 in which the clearance gap is provided between the said channel | path part of the said outermost piping, and the side wall of the said casing. It is attached to a part of the exhaust gas recirculation passage for recirculating the exhaust gas of the internal combustion engine to the intake system,
The heat exchanger according to any one of claims 1 to 5, wherein heat exchange is performed between exhaust gas flowing in the pipe and cooling water flowing outside the pipe in the casing.