JP6075381B2 - Heat exchanger - Google Patents

Description

  The present invention relates to a heat exchanger.

  Conventionally, various heat exchangers are known. For example, in Patent Document 1, a first fluid circulation part formed by a honeycomb structure having a plurality of cells through which a heating body as a first fluid circulates, and an outer peripheral part of the first fluid circulation part are provided. A heat exchanger having a second fluid circulation part is disclosed. The refrigerant flows through the second fluid circulation portion, takes heat from the heating body that circulates in the first fluid circulation portion, and cools the heating body. Patent Document 2 discloses an air-cooled semiconductor heat sink that includes a radial cooling surface and a cooling surface that is integrated with the radial cooling surface and that is concentric with respect to an axis. The radial cooling surface and the concentric cooling surface disclosed in Patent Document 2 are easy to secure a heat radiation area, and it is considered effective to be used in combination with the heat exchanger disclosed in Patent Document 1.

International Publication No. 2011/071161 JP 2003-100804 A1

  However, the combination of the radial cooling surface and the concentric cooling surface has room for further improvement in terms of heat transfer efficiency (thermal conductivity) in consideration of the arrangement of the refrigerant and the heating object to be cooled. It was.

  Therefore, an object is to obtain good thermal conductivity in the heat exchanger disclosed in this specification.

  In order to solve such a problem, the heat exchanger disclosed in the present specification is provided in at least one of a heat exchanger through which a fluid to be cooled passes, a center portion and an outer peripheral portion of the heat exchanger, A refrigerant passage through which a refrigerant that exchanges heat with the heat exchange body flows, the heat exchange body extending from a central portion toward an outer peripheral portion, a circumferential direction, and the first heat transfer means. A second heat transfer means that intersects with the first heat transfer means. The heat transfer efficiency of the first heat transfer means is higher than the heat transfer efficiency of the second heat transfer means. Here, the heat transfer efficiency is understood as a value obtained by multiplying the thermal conductivity, which is a physical property value of the material forming the heat exchanger, by the thickness per partition.

  The heat transfer efficiency toward the refrigerant passage is improved by setting the heat flow efficiency in the radial direction, that is, the heat transfer path toward the refrigerant passage provided in the center or outer periphery of the heat exchanger. Thereby, the favorable heat conductivity in a heat exchanger can be obtained and the cooling object can be cooled effectively.

  The first heat transfer means is a first partition that extends radially from the center of the heat exchanger to the outer periphery, and the second heat transfer means is a concentric second partition, and the first The thickness of the partition may be set larger than the thickness of the second partition. The concentric partition wall, that is, the second partition wall, can expand the contact area with the fluid to be cooled. On the other hand, the heat transfer efficiency of such a concentric partition wall must be lower than the heat transfer efficiency of the radially extending partition wall, that is, the first partition wall. Therefore, by setting the thickness of the first partition to be greater than the thickness of the second partition, the heat transfer efficiency of the first partition serving as the first heat transfer means is made higher than that of the second partition.

  The first heat transfer means is a first partition that extends radially from the center of the heat exchanger to the outer periphery, and the second heat transfer means is a concentric second partition, and the first The thermal conductivity of the partition wall material may be higher than the thermal conductivity of the second partition wall material. As described above, the concentric partition wall, that is, the second partition wall, can expand the contact area with the fluid to be cooled. On the other hand, the heat transfer efficiency of such a concentric partition wall must be lower than the heat transfer efficiency of the radially extending partition wall, that is, the first partition wall. Therefore, the first partition is made of a material having a thermal conductivity higher than that of the material forming the second partition, so that the heat transfer efficiency of the first partition serving as the first heat transfer means can be increased. Higher than that. In order to have a difference in thermal conductivity, the thermal conductivity can be made different between the material forming the first partition and the material forming the second partition. That is, the first partition can be formed of a material having a thermal conductivity higher than that of the material forming the second partition.

  The first heat transfer means is a first partition extending from an inlet side to an outlet side of a fluid to be cooled in the heat exchange body, and the second heat transfer means is a cooling object in the heat exchange body. A second partition extending from the inlet side to the outlet side of the fluid, and at least one of the thickness of the first partition and the second partition is made thinner as the thickness goes from the inlet side to the outlet side May be provided. The temperature of the fluid to be cooled is higher as it is closer to the inlet of the heat exchanger. Therefore, by increasing the thickness of the first partition and the second partition toward the side closer to the inlet, heat can be easily conducted to the refrigerant passage side, and temperature efficiency is increased.

  The first heat transfer means is a first partition extending from an inlet side to an outlet side of a fluid to be cooled in the heat exchange body, and the second heat transfer means is a cooling object in the heat exchange body. A second partition that extends from the inlet side to the outlet side of the fluid, and at least one of the thickness of the first partition and the second partition is made thicker as the thickness goes from the inlet side to the outlet side May be provided. This mode gives priority to the reduction of pressure loss. In the vicinity of the inlet of the heat exchanger, the temperature of the fluid is high and its volume is large. For this reason, when the flow path area is narrow, the influence on the pressure loss is increased, and the pressure loss is increased. Therefore, the pressure loss is reduced by reducing the thickness of the first partition and the second partition toward the side closer to the inlet, and the temperature efficiency is prevented from decreasing by increasing the thickness closer to the outlet.

  According to the heat exchanger disclosed in this specification, good thermal conductivity can be obtained.

FIG. 1 is an explanatory diagram showing a schematic configuration of a heat exchanger according to the first embodiment. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is an explanatory view showing the thicknesses of the first partition and the second partition. FIG. 4 is an explanatory view showing a modification in which the density of the second partition is changed. FIG. 5 is an explanatory view showing the arrangement of the second partition walls in the modification shown in FIG. FIG. 6 is an explanatory view showing a heat exchanger according to the second embodiment. FIGS. 7A to 7C are explanatory views showing a heat exchanger according to the third embodiment. FIGS. 8A to 8C are explanatory views showing a heat exchanger according to the fourth embodiment. FIG. 9 is an explanatory view showing an example in which the cross-sectional shape of the second partition is rectangular. FIG. 10 is an explanatory diagram showing an example in which the cross-sectional shape of the second partition wall is a spiral shape. FIG. 11 is an explanatory view showing an example in which the cross-sectional shape of the second partition is an elliptical shape. FIG. 12 is an explanatory view showing an example in which refrigerant passages are provided at the center and the outer periphery of the heat exchanger.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, in the drawings, the dimensions, ratios, and the like of each part may not be shown so as to completely match the actual ones. In some cases, details are omitted in some drawings.

(First embodiment)
First, the heat exchanger 1 of the first embodiment will be described with reference to FIGS. The heat exchanger 1 can cool various fluids. In the first embodiment, the heat exchanger 1 is incorporated in an exhaust gas recirculation device installed in an internal combustion engine and cools an EGR (Exhaust Gas Recirculation) gas. Used as a cooler. FIG. 1 is an explanatory diagram showing a schematic configuration of a heat exchanger 1 of the first embodiment. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is an explanatory view showing the thickness of the partition provided in the heat exchanger 1.

  The heat exchanger 1 includes an EGR pipe 2 through which EGR gas flows. The EGR pipe is a stainless steel (SUS) pipe material. The EGR pipe 2 can also use other materials such as aluminum. The heat exchanger 1 includes a housing member 3 that joins an end 3 a to an end 2 a of the EGR pipe 2 and forms a refrigerant passage 4 on the outer periphery of the EGR pipe 2. The housing member 3 is also made of stainless steel (SUS). The housing member 3 includes a refrigerant inlet 3b1 for introducing the refrigerant into the refrigerant passage 4 and a refrigerant outlet 3b2 for discharging the refrigerant in the refrigerant passage 4. Although any refrigerant may be used, in the present embodiment, cooling water is used. A stay 3 c is provided on the outer wall of the housing member 3.

  In the EGR pipe 2, a heat exchange element 5 disposed in contact with the inner peripheral wall surface 2 b of the EGR pipe 2 is accommodated. A fluid to be cooled, that is, EGR gas in the present embodiment, passes through the heat exchanger 5. The heat exchanger 5 is made of silicon carbide (SiC) ceramic. The ceramic material has efficient heat conduction and can exhibit high corrosion resistance. For this reason, the ceramic material which has high heat conductivity is suitable as a material of the heat exchange body and coating | coated member which are arrange | positioned in EGR piping. The heat exchange element 5 is formed in a cylindrical shape, and a passage is formed so that EGR gas can pass therethrough. The heat exchanger 5 can exchange heat with the refrigerant flowing through the refrigerant passage 4 via the EGR pipe 2. That is, when the EGR gas passes through the heat exchanger 5, the EGR gas exchanges heat with the refrigerant via the heat exchanger 5 and the EGR pipe 2 and is cooled.

  Referring to FIG. 2, the heat exchanger 5 includes first partition walls 5 a that extend radially from the center 6 toward the outer periphery as first heat transfer means extending from the center 6 toward the outer periphery. Moreover, the heat exchanger 5 is provided with concentric 2nd partition 5b as a 2nd heat transfer means extended along the circumferential direction and cross | intersected with the 1st partition 5a. Here, the central portion 6 is not required to be completely at the center of the heat exchange element 5. The 1st partition 5a should just form the heat transfer path | route which goes to the outer side from the inner side of the heat exchanger 5. In other words, it only needs to extend in the radial direction, and may be wavy or curved in the middle. On the other hand, the shape of the 2nd partition 5b should just be provided with the part continued in the circumferential direction. The second partition wall 5b may be circular, elliptical, or rectangular in a cross section orthogonal to the fluid flow direction. Moreover, it is not calculated | required that it is equipped with perfect cyclic | annular form, The thing of the shape where the cyclic | annular form was open | released may be sufficient. Such a 2nd partition 5b can improve the intensity | strength of the heat exchange body 5 by crossing the 1st partition 5a. Moreover, by providing the 2nd partition 5b, a contact area with a fluid can be increased and temperature efficiency can be improved.

  Here, referring to FIGS. 2 and 3, the thickness T1 of the first partition 5a is thicker than the thickness T2 of the second partition 5b. As described above, in the first embodiment, by changing the thickness of the first partition wall 5a and the second partition wall 5b, the heat transfer efficiency of the first heat transfer means, that is, the first partition wall 5a is changed to the second heat transfer efficiency. Means, that is, higher than the heat transfer efficiency of the second partition wall 5b. Thus, the heat transfer efficiency can be increased by increasing the thickness of the first partition wall 5a and increasing the thickness of the heat conduction path toward the refrigerant passage 4. Moreover, if the 2nd partition 5b is thickened, a pressure loss will increase correspondingly. However, in the first embodiment, since the second partition wall 5b is thin, pressure loss can be reduced, which contributes to improvement in thermal efficiency. Here, the second partition walls 5b can reduce the thickness of each sheet and increase the number of sheets. If the number of the second partition walls 5b increases, the contact area with the fluid can be further increased. As a result, the temperature efficiency is further improved. Even if the number of the second partition walls 5b is increased, an increase in pressure loss can be suppressed by reducing the thickness of the second partition walls 5b. Thus, reducing the thickness of each second partition 5b as the number of second partitions 5b increases satisfies the relationship between the thickness of the first partition 5a and the thickness of the second partition 5b. But it ’s convenient. Further, reducing the thickness of the second partition wall 5b is advantageous in securing the EGR gas channel area.

  Here, the comparison between the thickness of the first partition 5a and the thickness of the second partition 5b will be described in more detail. Even if the first partition wall 5a is locally thin and the thickness of the portion may be smaller than the thickness of an arbitrary position on the second partition wall 5b, the average of the first partition wall 5a The thickness should just be thicker than the average thickness of the 2nd partition 5b.

  If a heat exchanger with a square cell is accommodated in a cylindrical EGR pipe, it may be difficult to maintain the square in the vicinity of the EGR pipe, or the cell size may be reduced. End up. As a result, clogging is likely to occur, and the amount of EGR gas flowing in the outermost peripheral cell may be reduced, leading to a reduction in cooling efficiency. By combining the first partition wall 5a extending radially and the second partition wall 5b concentrically, it is possible to eliminate the inconvenience caused when a square cell is employed.

  Such a heat exchanger 1 includes cone members 8 on the upstream side and the downstream side of the EGR pipe 2. The upstream cone member 8 is a member that serves as an introduction part for introducing EGR gas into the EGR pipe 2, and the downstream cone member 8 is a member that serves as an EGR gas discharge part in the EGR pipe 2. The cone member 8 is joined to the housing member 3 by brazing so that the larger diameter side covers the end 3 a of the housing member 3. A flange member 9 is joined to the tip of the cone member 8 by brazing. The heat exchanger 1 is connected to the exhaust manifold of the engine by a flange member 9 on the upstream side. The heat exchanger 1 is connected to the intake pipe on the downstream side. The heat exchanger 1 is attached to the engine body by a stay 3c provided on the outer wall of the housing member 3.

  Here, the modification of 1st Embodiment is demonstrated, referring FIG. 4, FIG. FIG. 4 is an explanatory view showing a modification in which the density of the second partition is changed. FIG. 5 is an explanatory view showing the arrangement of the second partition walls in the modification shown in FIG.

  A plurality of second partition walls 5b are arranged concentrically. Here, the distance between the adjacent second partition walls 5b is expressed as Ln. n is a natural number that increases from the center 6 toward the outer periphery. The distance Ln increases toward the outer periphery. That is, the second partition walls 5 b are arranged more densely as the distance from the center portion 6 is closer. Thereby, the fluid, that is, the EGR gas easily flows as it approaches the outer peripheral portion side. In 1st Embodiment, the refrigerant path 4 is provided in the outer peripheral part. For this reason, in order to cool EGR gas efficiently, it is desirable to distribute a large amount of EGR gas through the outer peripheral portion close to the refrigerant passage 4. Therefore, by arranging the second partition walls 5b densely on the side closer to the central portion 6, more EGR gas can be flowed to the outer peripheral portion than the central portion, and the temperature efficiency can be improved.

  Note that the arrangement of the distances Ln may not be Ln-1 <Ln in the entire region. In short, it is only necessary that a portion where the second partition walls 5b are densely arranged is formed in a region close to the central portion 6.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIG. FIG. 6 is an explanatory view showing the heat exchanger 20 of the second embodiment. FIG. 6 corresponds to FIG. 2 for explaining the first embodiment. The heat exchanger 20 of the second embodiment differs from the heat exchanger 1 of the first embodiment in the following points. That is, the thermal conductivity of the material of the first partition 25a is higher than the thermal conductivity of the material of the second partition 5b. Moreover, the thickness of the 1st partition 25a and the thickness of the 2nd partition 25b are made the same. Since other components are the same, common components are denoted by the same reference numerals in the drawings, and detailed description thereof is omitted.

  The first partition wall 25a is made of a high thermal conductive ceramic. On the other hand, the second partition wall 25b is formed of a normal ceramic, that is, a ceramic whose thermal conductivity (thermal conductivity) is inferior to the material of the first partition wall 25a. Thereby, the heat taken by the first partition wall 25a and the second partition wall 25b from the fluid is easily transmitted toward the refrigerant passage 4 through the first partition wall 25a. Unlike the first embodiment, the heat exchanger 20 of the second embodiment can have the same thickness as the first partition wall 25a and the second partition wall 25b. For this reason, pressure loss can be reduced.

(Third embodiment)
Next, the heat exchanger 30 of the third embodiment will be described with reference to FIGS. FIG. 7A is an explanatory view of the heat exchanger 30 of the third embodiment as viewed from the inlet side. FIG. 7B is a cross-sectional view taken along line BB in FIG. FIG. 7C is an explanatory view of the heat exchanger 30 of the third embodiment viewed from the outlet side.

  The first partition 35a corresponding to the first heat transfer means extends from the EGR gas inlet side to the outlet side of the heat exchanger 35. And the thickness is made thin as it goes to the exit side from the entrance side. That is, the thickness Tin on the inlet side> the thickness Tout on the outlet side. The EGR gas flowing into the heat exchanger 35 is higher toward the inlet side. Therefore, on the inlet side, the thickness Tin on the inlet side is made larger than the thickness Tout on the outlet side in order to transfer more heat toward the refrigerant passage 4. Thereby, EGR gas can be cooled efficiently. In the example shown in FIGS. 7A to 7C, the thickness of the first partition wall 35a is changed. Here, the thickness of the second partition wall 35b extending from the EGR gas inlet side to the outlet side in the heat exchange element 35 is changed from the first partition wall 35a toward the outlet side with the first partition wall 35a. You can also make it thinner.

(Fourth embodiment)
Next, the heat exchanger 40 of the fourth embodiment will be described with reference to FIGS. FIG. 8A is an explanatory view of the heat exchanger 40 of the fourth embodiment as viewed from the inlet side. FIG. 8B is a cross-sectional view taken along the line CC in FIG. FIG. 8C is an explanatory view of the heat exchanger 40 of the fourth embodiment viewed from the outlet side.

  The first partition 45a corresponding to the first heat transfer means extends from the EGR gas inlet side to the outlet side of the heat exchanger 45. The thickness is increased from the entrance side toward the exit side. That is, the thickness on the inlet side Tin <the thickness Tout on the outlet side. Thereby, the pressure loss in an inlet_port | entrance can be reduced. In the vicinity of the inlet, the temperature of the EGR gas is high and the volume of the EGR gas is large. Therefore, if the flow path area is narrow, the influence on the pressure loss increases, and the pressure loss increases. Therefore, the thickness Tin on the inlet side is made thinner than the thickness Tout on the outlet side. Thereby, the fluid can be cooled efficiently. Moreover, the fall of temperature efficiency is suppressed by making the exit side thick. In the example shown in FIGS. 8A to 8C, the thickness of the first partition 45a is changed. Here, the thickness of the second partition wall 45b extending from the EGR gas inlet side to the outlet side in the heat exchanger 45 is changed from the first partition wall 45a to the outlet side from the inlet side to the outlet side. It can also be thickened according to

  The fourth embodiment is contrary to the third embodiment, but can be selected depending on which one is important.

(Modification)
Next, various modifications will be described.

  FIG. 9 shows a heat exchanger 50 in which the second partition wall 55b has a rectangular cross-sectional shape. Similar to the first embodiment, the heat exchanger 50 includes an EGR pipe 52, a housing 53, and a refrigerant passage 54, all of which have a rectangular cross section. Moreover, the heat exchange body 55 provided with the 1st partition 55a and the 2nd partition 55b is provided. Thus, even if it is a case where it is set as a cross-sectional rectangle, the structure similar to 1st Embodiment-4th Embodiment is employable.

  Next, FIG. 10 shows a heat exchanger 60 in which the cross-sectional shape of the second partition wall is a spiral shape. The heat exchanger 60 includes the EGR pipe 2, the housing 3, and the refrigerant passage 4 as in the first embodiment. And the heat exchange body 65 provided with the 1st partition 65a which cross | intersects the spiral 2nd partition 65b is provided. Thus, even if it is a case where the cross-sectional shape of the 2nd partition 65b is made into a spiral shape, the structure similar to 1st Embodiment-3rd Embodiment is employable.

  Next, FIG. 11 shows a heat exchanger 70 in which the cross-sectional shape of the second partition wall is elliptical. Similarly to the first embodiment, the heat exchanger 70 includes an EGR pipe 72, a housing 73, and a refrigerant passage 74, all of which have an elliptical cross section. Moreover, the heat exchange body 75 provided with the 1st partition 75a and the 2nd partition 75b is provided. Thus, even if it is a case where it is set as a cross-sectional ellipse, the structure similar to 1st Embodiment-3rd Embodiment is employable.

  Next, FIG. 12 shows a heat exchanger 80 in which refrigerant passages are provided at the center and the outer periphery of the heat exchanger. The heat exchanger 80 includes a refrigerant passage 11 disposed in the center portion in addition to the refrigerant passage 4 disposed in the outer peripheral portion. Even in such a case, the same configuration as that of the first to third embodiments can be employed. Thereby, heat can be efficiently transmitted to the refrigerant passage 4 and the refrigerant passage 11, and the EGR gas can be cooled.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope. For example, it can be used for applications other than the EGR cooler.

1, 20, 30, 40, 50, 60, 70 Heat exchanger 2 EGR piping 3, 53, 73 Housing 4, 54, 74 Refrigerant passage 5, 25, 55, 65, 75 Heat exchanger 5a, 25a, 55a, 65a, 75a 1st partition 5b, 25b, 55b, 65b, 75b 2nd partition

Claims (4)

A heat exchanger through which a fluid to be cooled passes;
A refrigerant passage that is provided in at least one of a center portion and an outer peripheral portion of the heat exchange body and through which a refrigerant that exchanges heat with the heat exchange body flows,
The heat exchanger includes a first partition that extends radially from the center toward the outer periphery, and a second partition that extends concentrically along the circumferential direction and intersects the first partition.
The heat transfer efficiency of the first partition is higher than the heat transfer efficiency of the second partition,
The thickness of the first partition wall is a heat exchanger that is thicker than the thickness of the second partition wall from the center to the entire outer periphery.   The heat exchanger according to claim 1, wherein the thermal conductivity of the material of the first partition is higher than the thermal conductivity of the material of the second partition. The at least one of the said 1st partition and the said 2nd partition is provided with the part thinned as the thickness goes to the exit side from the inlet side of the fluid used as the cooling object in the said heat exchanger. Heat exchanger. The at least one of the said 1st partition and the said 2nd partition is provided with the part thickened as the thickness goes to the exit side from the inlet side of the fluid used as the cooling object in the said heat exchange body. Heat exchanger.

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