Header-plate-less heat exchanger

Abstract

To reduce effects of cold and thermal stress generated in a tube without increasing the number of parts.SOLUTION: According to the present invention, a header-plate-less heat exchanger 1 includes a core 3 in which a plurality of flat tubes 2 with a first fluid circulating in an inner surface side are laminated, and a tank 4 with an end of the core 3 fitted thereto, and each flat tube 2 consists of a normal part 10 having an outside surface with a second fluid circulating, a gradual change part 11 in which an inner diameter continuously increases a diameter in a lamination direction from the normal part 10 toward the end side, and a lamination part 12 located at the end part to have an inner diameter increased by the gradual change part 11 and an outer surface brought into contact with another adjacent flat tube 2. In the heat exchanger, the tank 4 includes a cylindrical part 18 with the core 3 fitted thereinto, and a plurality of tube reinforcement parts 20 protruded from the cylindrical part 18 toward the normal part 10 and each brought into contact with a short side in the lamination direction of the plurality of flat tubes 2 at positions each corresponding to the plurality of flat tubes 2 in a lamination direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a header plateless heat exchanger. [Background technology]

[0002] In a heat exchanger such as an EGR (Exhaust Gas Recirculation) cooler, a header plate having a plurality of insertion holes through which a plurality of flat tubes are respectively inserted can be provided to increase the rigidity of the ends of the plurality of tubes in the flow direction, i.e., the tube ends, and the rigidity of a connecting member such as a tank provided to the tube ends of the plurality of tubes. Meanwhile, there is a so-called header plateless heat exchanger in which the ends of the stacked tubes are held by a header or tank without the above-mentioned header plate in order to reduce the number of parts.

[0003] For example, in a header-plateless heat exchanger disclosed in Patent Document 1, each plate is formed in a groove shape, and a pair of opposing plates are fitted together to form a flat tube, and the flat tube has expanded diameter parts at both ends that are expanded in the thickness direction. In addition, a plurality of flat tubes are stacked at the expanded diameter parts to form a core, the outer periphery of the core is covered with a casing, a header is disposed at one end of the core in the flow direction, and each part is fixed by brazing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-25649 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the header plateless heat exchanger described above, the number of parts can be reduced, but since there is no header plate to support each of the tubes, the rigidity of the stacked tubes in the flow direction and the rigidity of the header and tank provided on the tube end side are reduced. The rigidity of each tube can be increased by providing fins inside the tube, but the range in which the fins can be arranged on the tube is limited. Therefore, when a header plateless heat exchanger is constructed in which fins are not arranged on the tube end in the flow direction, the rigidity of the stacked tube end is reduced.

[0006] In a header plateless heat exchanger such as an EGR cooler, the heat of the fluid flowing through the tubes may cause thermal expansion of the tubes in the flow direction. At this time, a thermal stress is generated due to the difference in thermal expansion between the case or cover and the tubes, which may cause the tubes to deform in the stacking direction and break. In particular, in the area where the tubes are not provided with fins, the rigidity is low and cracks may occur. In a heat exchanger having a header plate, the header plate is configured with a plate thickness thicker than the tubes, so the rigidity of the tube ends can be increased. In contrast, a header plateless heat exchanger does not have such a header plate, so tubes with a plate thickness thinner than the header plate are joined together, resulting in a low rigidity of the tube ends.

[0007] In addition, the heat exchanger is configured such that a fluid (first fluid) flows inside the tubes, while a second fluid flows in a direction perpendicular to the stacking direction of the tubes and the flow direction of the first fluid. Therefore, if a reinforcing member is added to the outer surface of the tubes to suppress deformation or damage to the tubes, the flow of the second fluid will be hindered, increasing pressure loss and possibly deteriorating the performance of the heat exchanger. Furthermore, adding a new reinforcing member increases the number of parts and requires the alignment of many parts, which increases the number of assembly steps.

[0008] In heat exchangers such as EGR coolers, in which a core made of stacked tubes is covered with a case, it is not possible to visually check whether the reinforcing members that reinforce the tubes are attached, so there is a problem that if a reinforcing member is forgotten to be attached, it cannot be visually recognized.

[0009] The present invention has been made to solve the above-mentioned problems, and aims to provide a header plateless heat exchanger that can reduce the effects of thermal stress generated in the tubes without increasing the number of parts. [Means for solving the problem]

[0010] In order to achieve the above object, the present invention provides a core 3 in which a plurality of flat tubes 2 are stacked, through which a first fluid flows on the inner surface side and a second fluid flows on the outer surface side, and a tank 4 into which an end of the core 3 in the flow direction of the first fluid is fitted, the flat tubes 2 each having a normal portion 10 having an outer surface through which the second fluid flows, a gradually changing portion 11 that is continuous from the normal portion 10 toward the end side in the flow direction and has an inner diameter that is gradually enlarged in the stacking direction of the flat tubes 2, and a gradually changing portion 11 that is located at the end in the flow direction and has an inner diameter that is gradually enlarged in the stacking direction of the flat tubes 2. In the header plateless heat exchanger 1, which is composed of a stacked portion 12 having an inner diameter expanded at 11 and an outer surface in contact with other adjacent flat tubes 2, the tank 4 is characterized in having a cylindrical portion 18 into which the stacked portions 12 of the plurality of flat tubes 2 are fitted, and a plurality of tube reinforcing portions 20 which protrude from the cylindrical portion 18 toward the normal portion 10 at positions corresponding to each of the plurality of flat tubes 2 in the stacking direction and which respectively contact the short sides of the plurality of flat tubes 2 in the stacking direction.

[0011] In the present invention, the tube reinforcing portion 20 is preferably formed so as to reach the corresponding gradually changing portion 11 or the normal portion 10 of the flat tube 2 in the flow direction.

[0012] In the present invention, it is preferable that the tube reinforcing portion 20 is formed along the shape of the gradually changing portion 11 of the corresponding flat tube 2 when viewed from a direction perpendicular to the stacking direction and the flow direction.

[0013] In the present invention, the tube reinforcing portion 20 may be formed to reach the normal portion 10 of the corresponding flat tube 2 in the flow direction and may have a bridging portion 22 joined to another adjacent tube reinforcing portion 20. Effect of the Invention

[0014] According to the present invention, the influence of thermal stress occurring in a tube can be reduced without increasing the number of parts. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is an exploded perspective view showing an end portion of a header plateless heat exchanger according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a cross-sectional view showing a header plateless heat exchanger according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a side view showing a tube reinforcement portion and its surroundings in the header plateless heat exchanger according to the embodiment of the present invention. [Figure 4] FIG. 2 is a top view showing a tube reinforcing portion and its periphery according to the embodiment of the present invention. [Diagram 5] FIG. 11 is a side view showing an example of a tube reinforcement portion and its surroundings in a header plateless heat exchanger according to another embodiment of the present invention. [Figure 6] FIG. 11 is a side view showing another example of a tube reinforcement portion and its surroundings in a header plateless heat exchanger according to another embodiment of the present invention. [Figure 7] FIG. 11 is a top view showing a tube reinforcing portion and its periphery according to another example of an embodiment of the present invention. [Figure 8] FIG. 11 is a top view showing a tube reinforcing portion and its periphery according to another example of an embodiment of the present invention. [Figure 9]FIG. 11 is a top view showing a tube reinforcing portion and its periphery according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, a header plateless heat exchanger 1 according to an embodiment of the present invention will be described with reference to the accompanying drawings. Note that Fr, Rr, L, R, U, and D shown in each drawing indicate front, rear, left, right, top, and bottom, respectively. Terms indicating directions and positions are used in this specification, but these terms are used for convenience of explanation and do not limit the technical scope of the present invention.

[0017] FIG. 1 is an exploded perspective view showing the end of the header plateless heat exchanger 1, FIG. 2 is a cross-sectional view at the center of the header plateless heat exchanger 1 in a direction perpendicular to the left-right direction, FIG. 3 is a side view showing a tube reinforcement portion 20 and its surroundings in the header plateless heat exchanger 1, and FIG. 4 is a top view showing the tube reinforcement portion 20 and its surroundings.

[0018] 1 and 2, a header plateless heat exchanger 1 according to an embodiment of the present invention includes a core 3 in which a plurality of flat tubes 2 are stacked, tanks 4 disposed at the upstream and downstream ends of the flat tubes 2 in the flow direction, and a case 5 covering the outer periphery of the core 3. In the core 3, a first fluid such as a gas to be cooled (e.g., exhaust gas) flows on the inner surface side of the flat tubes 2, and a second fluid such as a refrigerant flows on the outer surface side of the flat tubes 2.

[0019] The flat tubes 2 are stacked in the up-down direction, and each flat tube 2 is flattened in a direction perpendicular to the stacking direction (left-right direction). The flat tubes 2 are in contact with adjacent flat tubes 2 at the upstream and downstream ends in the flow direction of the first fluid, and are stacked with other flat tubes 2 at other positions so as to be spaced apart from the adjacent flat tubes 2. For example, the flow direction of the first fluid is the front-rear direction of the flat tubes 2.

[0020] The flat tube 2 is formed into a cylindrical shape with a rectangular or elliptical cross section by fitting a pair of upper and lower plates 2a and 2b together, with the short side of the cross section extending in the vertical direction. In the flat tube 2, a first fluid is circulated on the inner surface side of the pair of fitted plates 2a and 2b, while a second fluid is circulated on the outer surface side (long side side of the cross section) of the plates 2a and 2b in a predetermined space between the adjacent flat tubes 2. In this embodiment, the flat tube 2 is configured so that the flow direction of the first fluid is the longitudinal direction.

[0021] The flat tubes 2 are formed such that the inner diameter in the stacking direction is expanded at the upstream end and downstream end in the flow direction of the first fluid, and the outer surfaces (upper and lower surfaces) at the expanded diameter positions are disposed in contact with adjacent flat tubes 2. Specifically, the flat tubes 2 have a normal portion 10 having an outer surface through which the second fluid flows, gradually changing portions 11 that are continuous with the normal portion 10 toward the upstream side and downstream side in the flow direction, respectively, and whose inner diameter is gradually expanded in the stacking direction, and stacked portions 12 that are located at the upstream end and downstream end in the flow direction, have an inner diameter expanded at the gradual changing portion 11, and have outer surfaces in contact with adjacent flat tubes 2.

[0022] The case 5 is made up of a case body 5a formed with a U-shaped cross section and an end cover 5b closing the opening of the U-shaped cross section, and is formed into a rectangular tube shape as a whole. The case 5 is the outer peripheral surface of the core 3 in which the flat tubes 2 are stacked, and covers the side surfaces (upper and lower surfaces, and left and right surfaces) of the flat tubes 2 other than the openings. The case 5 has a second inlet portion 15 for introducing the second fluid into the case 5 in order to circulate the second fluid to the outer surface side of the flat tubes 2 of the core 3 inside the case 5, and a second outlet portion 16 for discharging the second fluid that has circulated on the outer surface side of the flat tubes 2.

[0023] The tank 4 is placed over the open end of the flat tubes 2 of the core 3, i.e., the end in the flow direction of the first fluid. The tank 4 has an inlet tank 4a having a first inlet portion 13 for introducing the first fluid to circulate the first fluid to the inner surface side of the flat tubes 2 of the core 3, and an outlet tank 4b having a first outlet portion 14 for discharging the first fluid that has circulated through the flat tubes 2.

[0024] The tank 4 has a facing portion 17 facing the opening of the flat tube 2 of the core 3, and a cylindrical portion 18 formed in a continuous cylindrical shape from the ends (upper and lower ends, and left and right ends) of the facing portion 17 and covering the outer periphery of the end of the core 3 in the flow direction of the first fluid. The facing portion 17 has a first inlet portion 13 or a first outlet portion 14. The cylindrical portion 18 has an inner diameter substantially the same as the outer diameter of the outer periphery of the core 3, and is formed with a length covering the stacked portion 12 of the flat tube 2 of the core 3 in the flow direction of the first fluid. In other words, the stacked portion 12 is fitted into the cylindrical portion 18.

[0025] As shown in Figs. 3 and 4, the tank 4 includes a plurality of tube reinforcing parts 20 that support the ends of the flat tubes 2. In this embodiment, an example will be described in which the tanks 4 on the upstream and downstream sides in the flow direction of the first fluid are each integrally provided with a plurality of tube reinforcing parts 20. Each tank 4 includes a plurality of tube reinforcing parts 20 on at least one of the left and right sides of the core 3 (the plurality of flat tubes 2). The plurality of tube reinforcing parts 20 are formed at positions corresponding to the plurality of flat tubes 2 in the stacking direction of the plurality of flat tubes 2. The second fluid flows on the outer surface side of the flat tubes 2, and the tube reinforcing parts 20 are located at positions corresponding to the flat tubes 2, so are arranged to avoid the flow path of the second fluid. The plurality of tube reinforcing parts 20 are provided in contact with the short sides of the plurality of flat tubes 2 in the stacking direction.

[0026] The multiple tube reinforcement parts 20 are formed so as to protrude from the cylindrical part 18 toward each of the normal parts 10 of the multiple flat tubes 2, respectively, and to be parallel to the side surface (at least one of the left surface and the right surface) of the core 3 (multiple flat tubes 2). In other words, in the flow direction of the first fluid, the tube reinforcement part 20 of the tank 4 on the upstream side protrudes downstream along the flow direction, and the tube reinforcement part 20 on the downstream side protrudes upstream along the flow direction. The multiple tube reinforcement parts 20 are provided integrally with a base part 21 having the same height as the cylindrical part 18 in a comb-tooth shape, and the base part 21 may be formed integrally and continuously with the cylindrical part 18. The tube reinforcement part 20 and the base part 21 may be formed with the same thickness as the cylindrical part 18.

[0027] For example, in terms of length in the flow direction of the first fluid, the tube reinforcing portion 20 is formed so as to reach from the cylindrical portion 18 to the corresponding gradually changing portion 11 or normal portion 10 of the flat tube 2. In other words, the tube reinforcing portion 20 is formed to a length sufficient to cover at least the entire gradual changing portion 11.

[0028] Furthermore, the tube reinforcing portion 20 may be formed to have an outer shape that conforms to the shape of the corresponding gradually changing portion 11 of the flat tube 2 when viewed from a direction perpendicular to the stacking direction and the flow direction (left or right). In other words, the tube reinforcing portion 20 is formed in a shape that covers at least the gradual changing portion 11. Specifically, the tube reinforcing portion 20 is formed so as to become thinner in the stacking direction the farther it is from the cylindrical portion 18. After the tube reinforcing portion 20 reaches the normal portion 10, it is formed to a height that covers the normal portion 10 without changing its height in the stacking direction.

[0029] According to the header plateless heat exchanger 1 of the present embodiment described above, by providing the tank 4 with a plurality of tube reinforcing portions 20 that contact the plurality of flat tubes 2 individually, it is possible to increase the rigidity of the stacking portion 12 at the end of the flat tubes 2 in the flow direction of the first fluid without requiring any additional reinforcing member. This makes it possible to suppress deformation of the flat tubes 2 in the stacking direction, thereby reducing the effects of thermal stress occurring in the flat tubes 2. Furthermore, since no additional reinforcing member is required, it is possible to configure a header plateless heat exchanger 1 that can reduce the effects of thermal stress without increasing the number of parts or assembly steps.

[0030] Furthermore, since the multiple tube reinforcing parts 20 are integrally provided on the tank 4 so as to be arranged corresponding to each of the multiple flat tubes 2, it is possible to prevent forgetting to assemble the multiple flat tubes 2. Moreover, since the multiple tube reinforcing parts 20 are arranged on at least one of the left and right sides of the core 3 in a state in which the tank 4 is assembled to the core 3 consisting of the multiple flat tubes 2, the installation state of the multiple flat tubes 2 can be visually confirmed from the outside without removing the tank 4.

[0031] Furthermore, according to the header plateless heat exchanger 1 of this embodiment, the tube reinforcement portions 20 are formed to reach the corresponding gradual change portions 11 or normal portions 10 of the flat tubes 2, thereby further suppressing deformation of the flat tubes 2 in the stacking direction.

[0032] Furthermore, in the header plateless heat exchanger 1 according to this embodiment, the tube reinforcing parts 20 are formed to have an outer shape that conforms to the shape of the gradual change parts 11 of the corresponding flat tubes 2, and are arranged to avoid the flow path of the second fluid. This makes it possible to suppress an increase in pressure loss without impeding the flow of the second fluid, and therefore maintain the performance of the heat exchanger.

[0033] Furthermore, in the header plateless heat exchanger 1 according to another embodiment, as shown in Fig. 5 and Fig. 6, the tube reinforcement portion 20 is configured to have a bridging portion 22 joined to another adjacent tube reinforcement portion 20. The bridging portion 22 joins the tube reinforcement portion 20 to the other tube reinforcement portion 20 in the stacking direction. The bridging portion 22 is formed to have the same thickness as the tube reinforcement portion 20.

[0034] In another embodiment, the tube reinforcing portions 20 are formed to reach the corresponding normal portions 10 of the flat tubes 2 in the flow direction of the first fluid. For example, the bridging portions 22 are provided to join the same intermediate positions of the tube reinforcing portions 20 as shown in Fig. 5. Alternatively, the bridging portions 22 may be provided to join two intermediate positions of the tube reinforcing portions 20 in a staggered arrangement as shown in Fig. 6. The bridging portions 22 may be provided at positions corresponding to the normal portions 10 of the flat tubes 2 in the flow direction of the first fluid.

[0035] In this way, according to the header plateless heat exchanger 1 of another embodiment, even if the tube reinforcement portions 20 are formed relatively long, the tube reinforcement portions 20 are supported by the bridging portions 22, so that the rigidity of the tube reinforcement portions 20 can be increased, deformation of the flat tubes 2 can be further suppressed, and positional shifts of the tips of the tube reinforcement portions 20 can be suppressed.

[0036] In the above description of the embodiment of the present invention, the tube reinforcing portion 20 is formed parallel to the side surface (left or right surface) of the core 3 (plurality of flat tubes 2) along the flow direction of the first fluid, but the present invention is not limited to this example. In another example, the tube reinforcing portion 20 is formed so as to protrude from the cylindrical portion 18 toward the normal portion 10 of the flat tube 2 in the flow direction of the first fluid, and gradually toward the flat tube 2 in the direction perpendicular to the stacking direction and the flow direction.

[0037] Specifically, as shown in Fig. 7, the tube reinforcement portion 20 is formed so as to incline from the tubular portion 18 toward the flat tube 2 in a direction perpendicular to the stacking direction and the flow direction. Alternatively, as shown in Fig. 8, the tube reinforcement portion 20 is formed in a step-like manner from the tubular portion 18 toward the flat tube 2 in a direction perpendicular to the stacking direction and the flow direction. Figs. 7 and 8 show an example in which the tube reinforcement portion 20 on one side in the left-right direction (the right side) is formed so as to gradually approach the flat tube 2 in the direction perpendicular to the stacking direction and the flow direction, but alternatively, the tube reinforcement portion 20 on the other side in the left-right direction (the left side) may be formed in a similar manner, or the tube reinforcement portions 20 on both sides in the left-right direction may be formed in a similar manner.

[0038] In this other example, the flat tubes 2 have a constant width in the left-right direction between the upstream end and downstream end in the flow direction of the first fluid, and are formed so that the diameter is expanded not only in the stacking direction but also in the left-right direction at the upstream and downstream ends. Also, before the core 3 consisting of the flat tubes 2 is fitted into the cylindrical part 18 of the tank 4, the tube reinforcing part 20 is in a state in which it is opened outward in the direction perpendicular to the stacking direction and the flow direction, and after the core 3 is fitted into the cylindrical part 18, the tube reinforcing part 20 is bent toward the flat tubes 2 so as to be in contact with the flat tubes 2.

[0039] Alternatively, in yet another example, the tube reinforcement portion 20 protrudes from the tubular portion 18 toward the normal portion 10 of the flat tube 2 in the flow direction of the first fluid, and is formed so as to gradually move away from the flat tube 2 in the direction perpendicular to the stacking direction and the flow direction.

[0040] Specifically, as shown in Fig. 9, the tube reinforcement portion 20 is formed so as to be inclined from the cylindrical portion 18 toward the side away from the flat tube 2 in the direction perpendicular to the stacking direction and the flow direction. Alternatively, although not shown, the tube reinforcement portion 20 may be formed in a stepped shape from the cylindrical portion 18 toward the side away from the flat tube 2 in the direction perpendicular to the stacking direction and the flow direction. Fig. 9 shows an example in which the tube reinforcement portions 20 on both left and right sides are formed so as to gradually move toward the side away from the flat tube 2 in the direction perpendicular to the stacking direction and the flow direction, but alternatively, only the tube reinforcement portion 20 on one side (right side) or the other side (left side) in the left and right direction may be formed in the same manner.

[0041] In such other examples, the multiple flat tubes 2 have a constant width in the left-right direction between the upstream and downstream ends in the flow direction of the first fluid, and are formed so that their diameters expand in the stacking direction at the upstream and downstream ends but contract in the left-right direction.

[0042] In the above description of the embodiment of the present invention, the header plateless heat exchanger 1 has been described as having a plurality of tube reinforcing parts 20 provided on the upstream and downstream sides of the core 3 in which the plurality of flat tubes 2 are stacked in the flow direction of the first fluid, but the present invention is not limited to this example. In other examples, the plurality of tube reinforcing parts 20 may be provided on at least one of the upstream and downstream sides of the core 3 in the flow direction of the first fluid, and specifically, may be provided on the end of the core 3 on the upstream side where the higher temperature first fluid flows.

[0043] The above description of the embodiment of the present invention shows one aspect of the header plateless heat exchanger according to the present invention, and the technical scope of the present invention is not limited to the above embodiment. The present invention may be modified, substituted, or altered in various ways without departing from the spirit of the technical idea, and the claims include all embodiments that may be included within the scope of the technical idea. [Explanation of symbols]

[0044] 1 Header Plateless Heat Exchanger 2 Flat tube 2a, 2b plates 3 Cores 4. Tank 4a Inlet tank 4b Outlet tank 5 Cases 5a Case body 5b End cover 10 Regular part 11 Gradual change part 12 Laminated section 13 1st entrance 14 1st exit section 15 2nd entrance section 16 2nd exit section 17 Opposing part 18 Cylindrical section 20 Tube reinforcement 21 Base 22 Bridge

Claims

1. a core (3) in which a plurality of flat tubes (2) are stacked, through which a first fluid flows on the inner surface side and a second fluid flows on the outer surface side; a tank (4) into which an end of the core (3) in a flow direction of the first fluid is fitted, In the header plateless heat exchanger (1), the flat tubes (2) each include a normal portion (10) having an outer surface through which the second fluid flows, a gradually changing portion (11) that is continuous from the normal portion (10) toward an end side in the flow direction and has an inner diameter that is gradually increased in the stacking direction of the flat tubes (2), and a stacking portion (12) that is located at an end of the flow direction, has an inner diameter that is increased in the gradual changing portion (11), and has an outer surface that is in contact with another adjacent flat tube (2), The tank (4) has a cylindrical portion (18) into which the core (3) is fitted, and a plurality of tube reinforcing portions (20) that protrude from the cylindrical portion (18) toward the normal portion (10) at positions corresponding to each of the plurality of flat tubes (2) in the stacking direction and are in contact with each of the short sides of the plurality of flat tubes (2) in the stacking direction. A header plateless heat exchanger (1).

2. 2. The header plateless heat exchanger according to claim 1, wherein the tube reinforcement portion is formed to reach the gradually changing portion or the normal portion of the corresponding flat tube in the flow direction.

3. 2. The header plateless heat exchanger (1) according to claim 1, characterized in that the tube reinforcement portion (20) is formed along the shape of the gradual change portion (11) of the corresponding flat tube (2) when viewed from a direction perpendicular to the stacking direction and the flow direction.

4. 2. The header plateless heat exchanger (1) according to claim 1, characterized in that the tube reinforcement portion (20) is formed so as to reach the normal portion (10) of the corresponding flat tube (2) in the flow direction and has a bridging portion (22) joined to another adjacent tube reinforcement portion (20).

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