heat exchanger

Abstract

To provide a heat exchanger which includes a core having flat tubes composed of a pair of mating plates and header plates disposed at opposite ends thereof and which accurately manages insertion lengths of the flat tubes while securing joining lengths of the flat tubes with header plates.SOLUTION: A heat exchanger has a core 4 in which a large number of flat tubes 3 are stacked, and a pair of header plates 5 disposed at opposite ends thereof. The flat tubes 3 each include an outer plate 1 and an inner plate 2 which are fit to each other. Each of the outer plates 1 has a non-joined part 1b and a joined part 1a with the inner plates 2. At an end part of each flat tube 3, a claw 8 which is bent so as to protrude toward the outside of the flat tube 3 from the joined part 1a of the outer plate 1 is formed. The claw 8 has a planar end face 8a. With each flat tube 3 being inserted into a tube insertion hole 7 in the header plate 5, the end face 8a is in face contact with the vicinity of the tube insertion hole 7 in the header plate 5.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present invention relates to a heat exchanger having a core with a number of flat tubes composed of a pair of mating plates, and header plates disposed at both ends of the core. In particular, it relates to a device that more accurately controls the insertion length of the flat tubes while ensuring the joining length of each flat tube to the header plate.

Background Art

[0002] As a conventional heat exchanger used in an EGR cooler or the like, the one shown in FIG. 7 is known. This heat exchanger has a core 24 formed by a stack of flat tubes 23 in which a pair of plates facing each other are fitted. Header plates 25 are disposed at both ends of the core 24 as shown in FIG. 8A. A first fluid 35 flows through each flat tube 23. A casing 34 is fitted around the core 24, and header tanks 33 are fitted to both header plates 2... When inserting the flat tube 23 into the header plate 25, dimensional control of the insertion length L is necessary to ensure a sufficient joining length. On the other hand, when inserting the header tank 33 into the header plate 25 in the insertion direction shown in FIG. 8A, the gap between the flat tube 23 and the header plate 25 before brazing will move. When placed in the furnace during brazing, the header tank 25 on the outside heats up and expands, and the tip of each flat tube 23 is pushed into the tube insertion hole 27 more than necessary. A part of the insertion length L of the flat tube 23 in FIG. 8B protrudes from the header plate 25, and the extra length t tends to become long. In this heat exchanger, if the protrusion t of the flattened tube 23 from the tube insertion hole 27 of the header plate 25 is long, when the temperature change of the first fluid 35 becomes large, thermal stress will be generated at the tip of the flattened tube 23 upstream of the first fluid 35, in particular at the end of the flattened tube 23 and the tube insertion hole 27 of the header plate 25, and cracks 37 may occur in the flattened tube 23 as shown in Figure 8B. Even a slight change in the protrusion length t of the flattened tube 23 can cause significant fluctuations in the thermal stress generated when the temperature of the first fluid 35 changes. Furthermore, insufficient insertion length can lead to poor bonding between the header plate 25 and the flattened tube 23, causing leakage. Therefore, high precision is required for the insertion length L of the flattened tube 23 into the header plate 25, in order to minimize the protrusion length t as much as possible.

[0003] Patent Document 1 below proposes a solution to the problem shown in Figure 8A. The stopper structure described in Patent Document 1 controls the insertion length by a protrusion formed on the long side of a flattened tube. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2005-326066 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In the case of the stopper using a protrusion described in Patent Document 1, the protrusion must be formed on the long side of the flattened tube. Due to variations in the position of the protrusion formation, the flattened tube may be inserted at an angle, which may cause variations in the insertion length from the header plate on the opposing short side of the flattened tube. Furthermore, the base of the dimple is usually curved, and the contact of this curved surface with the header plate reduces the dimensional accuracy of the insertion length of the flattened tube into the header plate. In addition, if the tube insertion hole of the header plate is burred, the dimple will overlap the R portion of the burr on the header plate, further reducing the dimensional accuracy of the insertion length of the flattened tube into the header plate.

[0006] The present invention aims to provide a structure that allows for easy and highly accurate control of the insertion length of a flattened tube with a simple structure. [Means for solving the problem]

[0007] The present invention as described in claim 1 comprises a flattened tube 3 in which a pair of opposing outer plates 1 and inner plates 2 are fitted together, A core 4 made up of many flattened tubes 3 stacked together, It has a pair of header plates 5 positioned at both ends of the core 4, The header plate 5 has tube insertion holes 7 through which both ends of each flattened tube 3 are inserted. In a heat exchanger in which a first fluid 15 flows through each flattened tube 3, The outer plate 1 has a joint portion 1a and a non-joint portion 1b with respect to the inner plate 2. At least one end of the flattened tube 3 in the direction of flow of the first fluid 15 has a claw 8 formed thereon, which is bent to protrude outward from the joint 1a of the outer plate 1 toward the flattened tube 3. When the side of the header plate 5 facing the core 4 is considered the outer surface 6, The claw 8 has a planar end face 8a parallel to the outer surface 6. This heat exchanger has a flattened tube 3 inserted through a tube insertion hole 7 in a header plate 5, with the end face 8a in surface contact with the vicinity of the tube insertion hole 7 in the header plate 5.

[0008] The present invention as described in claim 2 is a heat exchanger as described in claim 1, The aforementioned claw 8 is a heat exchanger that protrudes from the edge 9 of the joint 1a of the outer plate 1.

[0009] The present invention as described in claim 3 is a heat exchanger as described in claim 1, The aforementioned claw 8 is a heat exchanger formed by bending a part of the joint portion 1a of the outer plate 1.

[0010] The present invention as described in claim 4 is a heat exchanger as described in claim 3, A pair of notches 10 are formed in the joint portion 1a of the outer plate 1. The aforementioned claw 8 is a heat exchanger formed between a pair of notches 10. [Effects of the Invention]

[0011] According to the invention described in claim 1, a claw 8 is formed on at least one end of the flattened tube 3 in the direction of flow of the first fluid 15, and is bent to protrude outward from the joint 1a of the outer plate 1. When the core 4 side surface of the header plate 5 is considered the outer surface 6, the claw 8 has a planar end surface 8a parallel to the outer surface 6, and the end surface 8a is in surface contact with the vicinity of the tube insertion hole 7 of the header plate 5 when the tip of the flattened tube 3 is inserted into the tube insertion hole 7 of the header plate 5. The configuration of this claw 8, which functions as a stopper, prevents the header plate 5 and the flat tube 3 from moving within the furnace by being pushed into the header tank 13. Furthermore, since the end face 8a of the claw 8 is planar and the end face 8a of the claw 8 makes surface contact with the vicinity of the tube insertion hole 7 of the header plate 5, the present invention improves the dimensional accuracy of the insertion length L of the flattened tube 3 into the header plate 5 compared to the structure described in Patent Document 1. Furthermore, even if the tube insertion hole 7 of the header plate 5 has a rounded section 12 such as a burring shape, by changing the length of the claw 8, it is possible to straddle the rounded section 12 and bring the outer surface 6 and the end surface 8a into surface contact, thereby improving the dimensional accuracy of the insertion length L of the flattened tube 3 into the header plate 5. On the other hand, it is difficult to form a stopper for embossing as described in Patent Document 1 on the short side of the flat tube. On the contrary, with the claw 8 of the present invention, a stopper structure can be easily formed.

[0012] When the claw 8 protrudes from the edge 9 of the joint portion 1a of the outer plate 1 as in the invention according to claim 2, when the flat tube 3 is inserted into the tube insertion hole 7 of the header plate 5, the variation in the insertion length of the flat tube 3 in the opposing short side portions can be reduced. Also, the claw 8 and the portion that becomes the short side of the outer plate 1 can be molded simultaneously.

[0013] When the claw 8 is formed from a part of the joint portion 1a of the outer plate 1 that is bent as in the invention according to claim 3, the material yield during the processing of the outer plate 1 can be improved.

[0014] When a pair of cutouts 10 are formed in the joint portion 1a of the outer plate 1 and the claw 8 is formed between the pair of cutouts 10 as in the invention according to claim 4, the material yield during the processing of the outer plate 1 can be improved and the configuration of the stopper can be easily formed.

Brief Description of the Drawings

[0015] [Figure 1A] It is an explanatory view of the heat exchanger of the present invention, a perspective view of the main part seen from the outer surface 6 side of the header plate 5 of the heat exchanger. [Figure 1B] Plan view of FIG. 1A [Figure 2] A view showing the state when the header tank 13 of the heat exchanger is fitted. [Figure 3A] A perspective view of the main part showing a first embodiment of the claw 8 formed on the flat tube 3 of the heat exchanger of the present invention. [Figure 3B] View taken in the direction of arrow B - B of FIG. 3A [Figure 3C] Development view of the outer plate 1 forming the flat tube 3 [Figure 3D] View taken in the direction of arrow D - D of FIG. 3B [Figure 4A] A perspective view of a main part showing a second embodiment of the claws 8 formed on the flattened tube 3 of the heat exchanger of the present invention. [Figure 4B] View from arrow BB in Figure 4A. [Figure 4C] View from the CC arrow in Figure 4B. [Figure 5A] A perspective view of the main part showing a third embodiment of the claws 8 formed on the flattened tube 3 of the heat exchanger of the present invention. [Figure 5B] View from arrow BB in Figure 5A. [Figure 5C] Developed view of the outer plate 1 that makes up the flattened tube 3. [Figure 5D] View from the DD arrow in Figure 5B. [Figure 6A] A perspective view of the main part showing a fourth embodiment of the claws 8 formed on the flattened tube 3 of the heat exchanger of the present invention. [Figure 6B] View from arrow BB in Figure 6A. [Figure 6C] Developed view of the outer plate 1 that makes up the flattened tube 3. [Figure 6D] View from the DD arrow in Figure 6B. [Figure 7] A perspective view of a conventional heat exchanger. [Figure 8A] Cross-sectional view taken along the line VIII-VIII in Figure 7. [Figure 8B] This diagram shows a crack 37 occurring in the flattened tube 23 of a conventional heat exchanger. [Modes for carrying out the invention]

[0016] Next, embodiments of the present invention will be described based on the drawings. Figure 1 is an explanatory diagram of the heat exchanger of the present invention, where Figure 1A is a perspective view of the main part of the heat exchanger as seen from the outer surface 6 side of the header plate 5, and Figure 1B is a plan view thereof. Figure 2 shows the state when the header tank 13 of the heat exchanger is fitted into place. This heat exchanger, for example, can be used in an EGR cooler, and as shown in Figures 1A and 1B, it has a core 4 made up of many stacked flat tubes 3, with a pair of header plates 5 positioned at both ends of the core 4. As shown in Figure 2, a first fluid 15 flows through each flat tube 3, and a second fluid 16 flows on the outside of the flat tubes 3. In Figures 1A and 1B, one side of the header plate 5 is shown, and the other side of the header plate 5 is omitted. The header plate 5 has tube insertion holes 7 through which both ends of each flat tube 3 are inserted. As shown in Figure 2, the outer circumference of the core 4 is fitted with a casing 14, and the ends of a header tank 13 are attached to the header plates 5. If the side of the header plate 5 facing the core 4 is considered the outer surface 6, then the edge of the tube insertion hole 7 in this example has the shape of a burring 11 that protrudes toward the inner surface side of the header tank 5 (header tank 13 side).

[0017] The flattened tube 3 that constitutes the core 4 consists of a fitting body of a pair of opposing outer plates 1 and inner plates 2, as shown in Figures 1A and 1B. The outer plate 1 and the inner plate 2 each have a pair of joint portions 1a and 2a and planar non-joint portions 1b and 2b, and the pair of joint portions 1a and 2a of each plate 1 and 2 are formed in a curved groove shape. The non-joint portion 1b of the outer plate 1 and the non-joint portion 2b of the inner plate 2 face each other, and the inner surface of the joint portion 1a of the outer plate 1 is fitted to the outer surface of the joint portion 2a of the inner plate 2, forming a flattened tube 3 having a short side portion 3a and a long side portion 3b.

[0018] A key feature of this embodiment is the shape of the stopper formed at the joint 1a of the outer plate 1. Figure 3 shows a first embodiment of the claws 8 formed on the flattened tube 3 of the heat exchanger of the present invention, Figure 3A is a perspective view of its main part, Figure 3B is a view taken along arrow BB in Figure 3A, Figure 3C is an unfolded view of the outer plate 1 constituting the flattened tube 3, and Figure 3D is a view taken along arrow DD in Figure 3B. In this first embodiment, the claw 8 constituting the stopper is formed to protrude integrally from the edge 9 of the joint portion 1a of the outer plate 1. As shown in Figures 3A, 3C, and 3D, the claw 8 is positioned retracted by the length L through which the flattened tube 3 is inserted from the tip of the outer plate 1 to the header plate 5.

[0019] As shown in Figure 3A, when the flattened tube 3 is formed, the claws 8 protrude outward from the short side portion 3a of the flattened tube 3. In this example, the tips of the claws 8 are raised parallel to the long side portion 3b of the flattened tube 3 from the edge 9 of the joint portion 1a of the outer plate 1. The claws 8 of each flattened tube 3 are formed at the same position (recessed by the insertion length L). The claws 8 have a flat end face 8a. As shown in Figures 1A and 1B, with the tip of each flattened tube 3 inserted from the outer side of the tube insertion hole 7 of the header plate 5, as shown in Figure 2, one end face 8a of the side of the claw 8 extends beyond the R portion 12 of the burring 11 near the tube insertion hole 7 of the header plate 5 and makes surface contact with the outer surface 6. By appropriately changing the length of the claw 8, it is possible to straddle the R portion 12, enabling highly accurate dimensional control of the insertion length L of the flattened tube 3 into the header plate 5.

[0020] Since each flattened tube 3 has a stopper claw 8 formed on its outer plate 1, the header plate 5 and the flattened tube 3 are pushed into the header tank 13 in the furnace, preventing movement. Furthermore, the protrusion t of the flattened tube 23 shown in Figures 8A and 8B of the background technology can be easily shortened to the minimum necessary, reducing thermal stress and making it easier to prevent cracks 37 from forming at the ends of the flattened tube 23. Furthermore, since the end face 8a of the claw 8 is planar in shape, and the end face 8a of the claw 8 makes surface contact with the vicinity of the tube insertion hole 7 on the outer surface 6 of the header plate 5, the present invention improves the dimensional accuracy of the insertion length L of the flattened tube 3 into the header plate 5 compared to the structure described in Patent Document 1.

[0021] Figure 4 shows a second embodiment of the claws 8 formed on the flattened tube 3 of the heat exchanger of the present invention, where Figure 4A is a perspective view of its main part, Figure 4B is a view taken along arrow BB in Figure 4A, and Figure 4C is a view taken along arrow CC in Figure 4B. The orientation of the tip of the claw 8 differs between the second embodiment and the first embodiment. In this second embodiment, the claw 8 is folded back from its base towards the joint portion 1a of the outer plate 1, as shown in Figures 4A and 4B. As shown in the second embodiment, by folding the claw 8 back from its base towards the joint 1a side of the outer plate 1, the influence on the flow of the second fluid 16 circulating on the outer surface of the flattened tube 3 inside the heat exchanger can be minimized.

[0022] Figure 5 shows a third embodiment of the claws 8 formed on the flattened tube 3 of the heat exchanger of the present invention, where Figure 5A is a perspective view of its main part, Figure 5B is a view taken along arrow BB in Figure 5A, Figure 5C is an unfolded view of the outer plate 1 constituting the flattened tube 3, and Figure 5D is a view taken along arrow DD in Figure 5B. When forming the claws 8 in the first and second embodiments, an additional amount of material is required equal to the length W2 of the claw formation allowance, which is added to the width W1 of the outer plate 1, resulting in poor yield. The third embodiment is a shape that improves the yield of this material. In this third embodiment, the claw 8 is formed from a part of the joint 1a of the outer plate 1. Specifically, as shown in Figure 5C, one of a pair of notches 10 is formed from the edge 9 which becomes the joint 1a of the outer plate 1 at a position recessed by the length L through which the flattened tube 3 is inserted into the header plate 5, and the other notch 10 is formed spaced apart from the first notch 10. The claw 8 in this example is formed within that pair of notches 10. By forming the claws 8 in this manner, the length W2 of the claw formation allowance on the outer plate 1 fits within the widthwise length W1 of the outer plate 1, thus improving yield. At the same time, the stopper structure can be easily formed.

[0023] Figure 6 shows a fourth embodiment of the claws 8 formed on the flattened tube 3 of the heat exchanger of the present invention, where Figure 6A is a perspective view of its main part, Figure 6B is a view taken along arrow BB in Figure 6A, Figure 6C is an unfolded view of the outer plate 1 constituting the flattened tube 3, and Figure 6D is a view taken along arrow DD in Figure 6B. In this fourth embodiment, as shown in Figure 6C, a U-shaped groove is formed between the boundary between the joint 1a and the non-joint 1b, and at a position recessed by the length L of the insertion length of the flattened tube 3 into the header plate 5, and from the end edge 9 which will be the joint 1a of the outer plate 1. In this example, the claw 8 is formed so as to be surrounded by the U-shaped groove. As shown in Figures 6A, 6B, and 6C, the claws 8 can also be formed by cutting from a point other than the end, and even with such claws 8, the yield can be improved. [Industrial applicability]

[0024] It can be used in heat exchangers such as EGR coolers. [Explanation of Symbols]

[0025] 1 Outer plate 1a Joint 1b Non-joint part 2 Inner Plate 2a joint 2b Non-joint part 3. Flat tube 3a Short side 3b Long side 4 cores 5 Header Plate 6 External surface

[0026] 7 Tube insertion hole 8 claws 8a End face 9 Edge 10 Notches 11 Burring 12 R section 13 Header Tank 14 Casing 15 1st fluid 16 Second fluid L insertion length W1 Outer plate 1 width W2 Nail 8 length of preparation

[0027] 23 Flat tube 24 cores 25 Header Plate 27 Tube insertion hole 33 Header Tank 34 Casing 35 1st fluid 36 Second fluid 37 Cracks t Expenses

Claims

1. A flattened tube (3) in which a pair of opposing outer plates (1) and inner plate (2) are fitted together, A core (4) made up of many flattened tubes (3) stacked together, It has a core (4) and a pair of header plates (5) positioned at both ends, The header plate (5) has tube insertion holes (7) through which both ends of each flattened tube (3) are inserted. In a heat exchanger through which a first fluid (15) flows in each flattened tube (3), The outer plate (1) has a joint portion (1a) and a non-joint portion (1b) with respect to the inner plate (2). At least one end of the flattened tube (3) in the direction of flow of the first fluid (15) has a claw (8) formed thereon that is bent to protrude outward from the joint (1a) of the outer plate (1) toward the flattened tube (3). When the side of the header plate (5) facing the core (4) is considered the outer surface (6), The claw (8) has a planar end face (8a) parallel to the outer surface (6), With the tip of the flattened tube (3) inserted into the tube insertion hole (7) of the header plate (5), the end face (8a) is in surface contact with the vicinity of the tube insertion hole (7) of the header plate (5). A heat exchanger in which the claws (8) protrude from the edge (9) of the joint (1a) of the outer plate (1).

2. A flattened tube (3) having a pair of opposing outer plates (1) and inner plate (2) fitted together, A core (4) made up of many flattened tubes (3) stacked together, It has a core (4) and a pair of header plates (5) positioned at both ends, The header plate (5) has tube insertion holes (7) through which both ends of each flattened tube (3) are inserted. In a heat exchanger through which a first fluid (15) flows in each flattened tube (3), The outer plate (1) has a joint portion (1a) and a non-joint portion (1b) with respect to the inner plate (2). At least one end of the flattened tube (3) in the direction of flow of the first fluid (15) has a claw (8) formed thereon that is bent to protrude outward from the joint (1a) of the outer plate (1) toward the flattened tube (3). When the side of the header plate (5) facing the core (4) is considered the outer surface (6), The claw (8) has a planar end face (8a) parallel to the outer surface (6), With the tip of the flattened tube (3) inserted into the tube insertion hole (7) of the header plate (5), the end face (8a) is in surface contact with the vicinity of the tube insertion hole (7) of the header plate (5). The claws (8) are heat exchangers formed by bending a part of the joint (1a) of the outer plate (1).

3. In the heat exchanger according to claim 2, A pair of notches (10) are formed in the joint (1a) of the outer plate (1), The claws (8) are heat exchangers formed between a pair of notches (10).

4. A flattened tube (3) having a pair of opposing outer plates (1) and inner plate (2) fitted together, A core (4) made up of many flattened tubes (3) stacked together, It has a core (4) and a pair of header plates (5) positioned at both ends, The header plate (5) has tube insertion holes (7) through which both ends of each flattened tube (3) are inserted. In a heat exchanger through which a first fluid (15) flows in each flattened tube (3), The outer plate (1) and the inner plate (2) each have a pair of joint portions (1a, 2a) and planar non-joint portions (1b, 2b), The flattened tube (3) has a non-joint portion (1b) and a non-joint portion (2b) facing each other, and a short side portion (3a) formed by fitting the inner surface of the joint portion (1a) to the outer surface of the joint portion (2a), and a long side portion (3b). At least one end of the flattened tube (3) in the direction of flow of the first fluid (15) has a claw (8) formed thereon which is bent to protrude outward from the flattened tube (3) from the joint (1a) of the outer plate (1) and the short side portion (3a) of the flattened tube (3). When the side of the header plate (5) facing the core (4) is considered the outer surface (6), The claw (8) has a planar end face (8a) parallel to the outer surface (6), A heat exchanger in which the tip of a flattened tube (3) is inserted into a tube insertion hole (7) of a header plate (5), and the end face (8a) is in surface contact with the vicinity of the tube insertion hole (7) of the header plate (5).

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