Patent Application
20190154361
The disclosure of Japanese Patent Application No. 2017-223910 filed on Nov. 21, 2017 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
The present disclosure relates to a heat exchange device.
A heat exchange device that is used to cool a fluid for an internal combustion engine of an automobile or the like is known. The heat exchange device includes a first flow path and a second flow path through which a first fluid and a second fluid respectively flow and heat is exchanged between the first fluid and the second fluid. For example, in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2010-503817 (JP 2010-503817 A), a tubular partition wall that separates the first flow path and the second flow path such that the first flow path and the second flow path are positioned inward and outward of the partition wall, respectively. Fins that protrude inward from an inner circumferential surface of the partition wall are integrally formed with the partition wall. With the fins as described above, it is possible to secure a heating surface area between the first fluid and the second fluid such that there is an improvement in heat exchange efficiency.
It is desired to further improve the heat exchange efficiency of a heat exchange device as described above.
The present disclosure provides a heat exchange device with improved heat exchange efficiency.
An aspect of the present disclosure relates to a heat exchange device including a first flow path, a second flow path, an offset fin, and a pressing member. The first flow path is configured such that a first fluid flows through the first flow path. The second flow path is configured such that a second fluid flows through the second flow path, the second flow path is separated from the first flow path by a tubular partition wall, and the second flow path is positioned close to an outer circumference of the tubular partition wall. The offset fin is installed in a tubular shape extending along an inner circumferential surface of the tubular partition wall. The pressing member is disposed inward of the offset fin such that the offset fin is pressed toward the inner circumferential surface of the partition wall while being elastically deformed. The offset fin is provided with a plurality of wave-shaped portions arranged in an axial direction of the tubular partition wall, and the wave-shaped portions are provided such that the positions of wave-shapes of the wave-shaped portions adjacent to each other offset from each other in a circumferential direction of the tubular partition wall. Since the offset fin is adopted, it is possible to secure a heating surface area between the first fluid and the second fluid. In addition, since the pressing member presses the offset fin toward the inner circumferential surface of the partition wall with the offset fin elastically deformed, the offset fin comes into close contact with the inner circumferential surface. Accordingly, heat is efficiently transmitted between the first fluid and the second fluid and there is an improvement in heat exchange efficiency.
In the heat exchange device according to the aspect of the present disclosure, the pressing member may be a solid shaft.
In the heat exchange device according to the aspect of the present disclosure, the pressing member may be provided with a guiding portion configured to guide the first fluid toward the offset fin side.
In the heat exchange device according to the aspect of the present disclosure, the pressing member may be provided with a tubular portion configured to press the offset fin toward the inner circumferential surface side and an opening portion provided in a circumferential wall of the tubular portion and the guiding portion may guide the first fluid toward the offset fin side from an area in the tubular portion through the opening portion.
In the heat exchange device according to the aspect of the present disclosure, the guiding portion may spirally extend in an axial direction of the first flow path.
In the heat exchange device according to the aspect of the present disclosure, the pressing member may be provided with a blocking portion configured to block a space surrounded by the offset fin, the blocking portion being provided in an end portion of the pressing member that is on a downstream side in the first flow path.
According to the aspect of the present disclosure, it is possible to provide a heat exchange device with improved heat exchange efficiency.
Features, advantages, and technical and industrial significance of exemplary embodiments of the present disclosure will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:
An exhaust gas and a coolant flow through the exhaust gas flow path 20 and the coolant flow path 30, respectively. The exhaust gas flow path 20 constitutes a portion of the EGR path. The coolant cools the engine and the temperature of the coolant is lower than that of the exhaust gas. The exhaust gas flow path 20 and the coolant flow path 30 are separated from each other by a partition wall 15. The coolant flow path 30 is formed to be disposed outward of the partition wall 15 and the exhaust gas flow path 20 is formed to be disposed inward of the partition wall 15. The partition wall 15 is formed in an approximately cylindrical shape and is provided with an inner circumferential surface 151 and an outer circumferential surface 152. The coolant flow path 30 is provided with an inner circumferential surface 301 having a cylindrical shape. The outer circumferential surface 152 of the partition wall 15 faces the inner circumferential surface 301 of the coolant flow path 30. The exhaust gas and the coolant are examples of a first fluid and a second fluid, respectively. The exhaust gas flow path 20 and the coolant flow path 30 are examples of a first flow path and a second flow path through which the exhaust gas and the coolant flow, respectively. The inner circumferential surface 151 of the partition wall 15 is an example of an inner circumferential surface of the first flow path.
In the exhaust gas flow path 20, an offset fin 40 and a pressing member 50 are disposed. The offset fin 40 is installed in the exhaust gas flow path 20 in a state of being elastically deformed into a cylindrical shape. The pressing member 50 is press-fitted to be disposed inward of the offset fin 40 having the cylindrical shape. The pressing member 50 is a solid shaft provided with an outer circumferential surface 501 having a cylindrical shape. In other words, the pressing member 50 has a columnar shape. The pressing member 50 is, for example, formed of metal, such as stainless steel. The exhaust gas flows in an area between the inner circumferential surface 151 of the partition wall 15 and the outer circumferential surface 501 of the pressing member 50 and flows in the vicinity of the offset fin 40. When the offset fin 40 is provided in the exhaust gas flow path 20 as described above, a heating surface area between the exhaust gas and the coolant can be secured and there is an improvement in heat exchange efficiency.
In a case where the partition wall 15 and the pressing member 50 are coaxially disposed, a distance between the inner circumferential surface 151 of the partition wall 15 and the outer circumferential surface 501 of the pressing member 50 in a radial direction is set to be smaller than the thickness of the entire offset fin 40 before the elastic deformation. Therefore, as illustrated in
As described above, the pressing member 50 presses the offset fin 40 toward the inner circumferential surface 151 of the partition wall 15. Here, there may be a case where the pressing member 50 is not provided. For example, there may be a case where the upper wall portion 42 of the offset fin 40 does not come into close contact with the inner circumferential surface 151. In this case, heat of the exhaust gas that is received by the offset fin 40 may not be efficiently transmitted to the coolant via the partition wall 15 and there may be a decrease in heat exchange efficiency.
In the present embodiment, the pressing member 50 presses the offset fin 40 toward the inner circumferential surface 151 of the partition wall 15 and thus the upper wall portion 42 of the offset fin 40 comes into close contact with the inner circumferential surface 151. Therefore, heat is efficiently transmitted between the exhaust gas and the coolant via the offset fin 40 and the partition wall 15 and thus there is an improvement in heat exchange efficiency.
Since the pressing member 50 presses the offset fin 40 toward the inner circumferential surface 151 of the partition wall 15, wobbling of the offset fin 40 in the exhaust gas flow path 20 is suppressed. Therefore, wobbling of the offset fin 40 which is caused by vibration of the engine and an increase in noise which is caused by the wobbling are suppressed. Since positional deviation of the offset fin 40 in an axial direction is also suppressed, the offset fin 40 can be continuously held at a desired position at which an excellent heat exchange efficiency can be achieved.
Both of the outer circumferential surface 501 of the pressing member 50 and the inner circumferential surface 151 of the partition wall 15 have a cylindrical shape and the thickness of the offset fin 40 is uniform. Therefore, the offset fin 40 elastically deformed into a cylindrical shape can uniformly come into close contact with the inner circumferential surface 151 regardless of the position in the circumferential direction, and thus there is an improvement in heat exchange efficiency.
Since the pressing member 50 is a solid shaft, the strength of the pressing member 50 is secured. Accordingly, for example, when manufacturing the heat exchange device 1, it is possible to press-fit the pressing member 50 such that the pressing member 50 is disposed inward of the offset fin 40 that is disposed in a cylindrical shape extending along the partition wall 15, without consideration of deformation of the pressing member 50. Therefore, it is possible to manufacture the heat exchange device 1 in a short time and thus it is possible to suppress an increase in manufacturing cost.
A heat exchange device in a modification example will be described. Note that, the same configurations as in the embodiment will be given the same reference numerals and repetitive description thereof will be omitted.
A plurality of opening portions 53a is formed in a circumferential wall of the tubular portion 51a such that the opening portions 53a are disposed at different positions in the circumferential direction and the axial direction of the tubular portion 51a. The opening portions 53a are formed to have isosceles triangular shapes. Guiding portions 55a are erected toward an area in the tubular portion 51a at positions downstream of the opening portions 53a. The guiding portions 55a block the opening portions 53a before being erected and the guiding portions 55a and have isosceles triangular shapes as with the opening portions 53a. The guiding portions 55a are erected toward the area in the tubular portion 51a at an angle of less than 90 degrees. Therefore, the exhaust gas intruding into the tubular portion 51a is guided toward the offset fin 40 side by the guiding portions 55a through the opening portions 53a.
The downstream side end of the tubular portion 51a is provided with the blocking portion 57a and the blocking portion 57a blocks a space surrounded by the tubular portion 51a. Therefore, the exhaust gas intruding into the tubular portion 51a is restrained from passing through the tubular portion 51a without flowing in the vicinity of the offset fin 40. Accordingly, the exhaust gas intruding into the tubular portion 51a is guided toward the offset fin 40 side and thus there is an improvement in heat exchange efficiency.
As described above, the opening portions 53a and the guiding portions 55a are formed to be disposed at different positions in the circumferential direction and the axial direction of the tubular portion 51a. Therefore, the exhaust gas intruding into the tubular portion 51a is restrained from being unevenly guided to a position on the offset fin 40 side. This feature also results in an improvement in heat exchange efficiency. Since the pressing member 50a is not solid, the weight of the pressing member 50a is light in comparison with a case where the pressing member 50a is solid. An increase in amount of heat accumulated in the pressing member 50a which is caused by the exhaust gas is also suppressed and the exhaust gas can be efficiently cooled.
A plurality of slits is formed in the flat plate portion 51a′ through slit processing, the slits having a V-shape when seen in such a manner that the upstream side in a direction in which the exhaust gas flows is on the lower side. Portions surrounded by the slits are erected toward the same side with respect to the flat plate portion 51a′ such that the opening portions 53a and the guiding portions 55a are formed at the same time. Since it is possible to form the opening portions 53a and the guiding portions 55a at the same time with a simple process as described above, an increase in the number of components or an increase in manufacturing cost is suppressed.
The serrated portion 57a′ is erected toward the same side as the guiding portions 55a and the flat plate portion 51a′ is plastically deformed into a cylindrical shape such that tip ends of the serrated portion 57a′ come into contact with each other. In this manner, the pressing member 50a provided with the blocking portion 57a is manufactured. As described above, the blocking portion 57a is also integrally formed with one sheet of stainless steel, an increase in the number of components or an increase in manufacturing cost is suppressed. Note that, although the above-described configuration is preferable, the configuration is not limited to this and the tubular portion 51a formed with the opening portions 53a, the guiding portions 55a, and the blocking portion 57a may be bonded to each other through welding or the like after being separately manufactured.
The shapes of the opening portions 53a and the guiding portions 55a are not limited to those described above and may be square shapes, trapezoidal shapes, semi-circular shapes, or the like. The positions, the sizes, and the numbers of the opening portions 53a and the guiding portions 55a are not limited to those in the above example. Note that, in order to guide the exhaust gas to the offset fin 40 side from the area in the tubular portion 51a through the opening portions 53a, the areas and sizes of the opening portions 53a are preferably designed such that the offset fin 40 cannot be completely blocked by the bottom wall portions 46.
As illustrated in
Here, the guiding portions 56b are positioned downstream of the guiding portions 55b and an axial pitch interval P6 between the guiding portions 56b is formed to be smaller than an axial pitch interval P5 between the guiding portions 55b. Therefore, the exhaust gas can be sufficiently guided to the offset fin 40 side by the guiding portions 56b on the downstream side. Note that, although the above-described configuration is preferable, the configuration is not limited to this and axial pitch intervals between the spiral-shaped guiding portions may be constant.
The diameters of outer circumferential edges 501b of the guiding portions 55b, 56b are constant, and the outer circumferential edges 501b press the offset fin 40 toward the inner circumferential surface 151 of the partition wall 15. Therefore, there is an improvement in heat exchange efficiency. As with the pressing member 50a, the pressing member 50b is not solid. Therefore, the weight of the pressing member 50b is light and an increase in amount of accumulated heat is suppressed.
A blocking portion 57b is formed in a downstream side end of the guiding portion 56b and is formed in an approximately circular shape. Therefore, a larger amount of exhaust gas can be guided toward the offset fin 40 side and there is an improvement in heat exchange efficiency.
The guiding portions 55b, the guiding portions 56b, and the blocking portion 57b are integrally molded with each other by subjecting a single metal plate to a shearing process and a bending process. Therefore, an increase in the number of components or an increase in manufacturing cost is suppressed in comparison with a case where the guiding portions 55b, the guiding portions 56b, and the blocking portion 57b are separately formed. Note that, although the above-described configuration is preferable, the configuration is not limited to this and the guiding portions 55b, the guiding portions 56b, and the blocking portion 57b may be bonded to each other through welding after being separately manufactured.
The pressing member 50b is not provided with a central shaft. However, the pressing member 50b may be provided with a central shaft and the guiding portions 55b, 56b are provided around the central shaft.
Hereinabove, the embodiment of the present disclosure has been described. However, the embodiment of the present disclosure is not limited to a specific embodiment as described above and various modifications and changes can be made without departing from the gist of the present disclosure described in embodiments above.
In the embodiment and the modification examples, the offset fin 40 comes into direct contact with the inner circumferential surface 151 of the partition wall 15. However, the configuration is not limited to this and a cylindrical member formed of material with excellent thermal conductivity may be interposed between the offset fin 40 and the inner circumferential surface 151.
In the embodiment and the modification examples, the inner circumferential surface 151 of the partition wall 15 has a cylindrical shape. However, the configuration is not limited to this and the inner circumferential surface 151 may have an elliptical cylindrical shape or a rectangular tubular shape. In this case, it is desirable that the outer circumferential surface and an outer circumferential edge of the pressing member also have an elliptical cylindrical shape or a rectangular tubular shape in order to be matched with the shape of the inner circumferential surface 151. This is because the offset fin can come into close contact with the inner circumferential surface 151 of the partition wall 15 with a uniform force at every position in the circumferential direction in this case.
In the modification examples described above, the blocking portions 57a, 57b may not completely block the space surrounded by the offset fin 40 as long as the flow rate of the exhaust gas passing through the space surrounded by the offset fin 40 can be reduced.
In the embodiment and the modification examples, the offset fin 40 extends in the plane direction as illustrated in
In the embodiment and the modification examples, the description has been made by using a case in which the heat exchange device is integrally provided in the engine as an example. However, the configuration is not limited to this and, for example, the heat exchange device may be integrally formed with the exhaust gas path. For example, a double-pipe structure may be adopted such that the first fluid flows in an inner pipe and the second fluid flows between an outer pipe and the inner pipe. The heat exchange device in the embodiment and the modification examples may be applied to, for example, a system other than an engine that uses a thermodynamic cycle. The description has been made by using gas and liquid as examples of the first fluid and the second fluid, respectively. However, the configuration is not limited to this and the first fluid and the second fluid may be liquid and gas respectively and both of the first fluid and the second fluid may be gas or liquid.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-223910 | Nov 2017 | JP | national |
