JP2003130566A - Flat tube for heat exchanger and heat exchanger using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat tube for a heat exchanger and a heat exchanger for a vehicle or the like, capable of overcoming the disadvantage of a flat tube used in the conventional heat exchanger, wherein the area of a joint part forming a passage is small, the compressive strength is low, the spread of flux to the joint part is poor to easily cause joining failure, and the shape is complicated to increase the machining cost. SOLUTION: In this flat tube for the heat exchanger, the flat tube for performing heat exchange is formed by bending both end parts of a metallic plate to form side parts, mutually opposing two thus formed plates having a U-shaped section, and mutually superposing the plates with one U-shaped section plate inserted in the inside of the other U-shaped section plate to form a passage inside. Thus, the flat tube can be simply manufactured by press working, and the working cost can be reduced by combination with simplification of a shape. The joint part can be made wider by superposing the side parts to attain excellent compressive strength, and the joint parts can be easily accessed to spread flux well so that the occurrence of joining failure can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiator for cooling engine cooling water, a flat tube for a heat exchanger used in a heat exchanger such as a heater core of a hot water heater, and a heat exchanger using the same.

[0002]

2. Description of the Related Art In a vehicle, a radiator for cooling water, or a passenger compartment for cooling cooling water heated by cooling an operating engine with air flowing into the vehicle at a speed relative to the atmosphere during traveling. A heat exchanger such as a hot water heater that cools the engine and heats the air taken in from the outside and the air taken in from the passenger compartment into the room to heat the room. Is used.
FIG. 5 is a perspective view showing the outer appearance of the entire heater core used in a heat exchanger of such a hot water heating system for vehicles.
FIG. 6 is a partially enlarged view of a conventional heater core, FIG. 7 (a),
(B) And (c) is an enlarged view of the flat tube cross-sectional shape used for the conventional heater core.

As shown in FIGS. 5 and 6, the heater core 1
Is a flat plate of a plurality of examples in which the width direction of the side surface is arranged mainly in the air flow direction that crosses the heater core 1 indicated by the white arrow 10, and is arranged upright substantially at equal intervals in the lateral direction orthogonal to the air flow direction 10. The tubes 2 and the corrugated fins 3 having both end portions joined to the side surfaces of the flat tubes 2 and arranged between the flat tubes 2 and having a corrugation in a direction orthogonal to the air flow direction 10 are formed. . In addition, each flat tube 2 is formed with a flow passage 11 for cooling the vehicle engine and flowing the heated cooling water inside the flat tube 2. Normally, the cooling water heated together with the corrugated fins 3 heats the vehicle interior. It is made of copper, aluminum, or the like having a high thermal conductivity in order to increase the efficiency of heat transfer to the air flow.

Further, the heater core 1 has header plates 6 and 7 which communicate with the upper and lower ends of each flat tube 2.
Is provided, and the header plate 6 has a cooling water inlet pipe 8
And an upper tank 4 equipped with a cooling outlet pipe 9 and a lower tank 5 attached to the header plate 7, respectively. The cross-sectional shape of the flat tube 2 conventionally used for such a heater core 1 is
Usually, the shapes shown in FIGS. 7A, 7B and 7C are used.

That is, FIG. 7 (a) is a transverse sectional view showing the first example, and as shown in the figure, the flat tube 2a has a metal plate 21 made of copper or aluminum or the like, which is formed at both ends 22 by roll forming. Is bent in a semicircle shape, and both ends 22
Are butt-contacted with each other and the contact portion is welded to form the flat tube 2a, and the flow path 11 for the cooling water is formed therein.

FIG. 7 (b) is a cross-sectional view showing a second example of the flat tube 2b. As shown in the figure, both ends 24 of the flat tube 2b are formed by roll forming a metal plate 23 of copper or aluminum. Is bent into an L-shape, both L-shaped bent portions 25 are butted back to back, and simultaneously brazed when the heater core 1 is brazed to form the flat tube 2b. To form.

Further, FIG. 7 (c) is a cross-sectional view showing the third example, and as shown in the figure, the flat tube 2c is processed in the same manner as the flat tube 2b, and the central portion of the metal plate 26 is folded back. To form the inner pillar portion 28, and to butt the L-shaped bent portions 27 having both ends bent back to back on both sides of the inner pillar portion 28, and simultaneously brazing these when the heater core 1 is brazed to form the flat tube 2c. Along with the formation, the cooling water flow path 11 is formed therein.

However, in the above-mentioned conventionally used flat tube 2, which flat tube 2a,
2b and 2c also have the following problems. That is,
The flat tube 2a of the first example shown in FIG. 7 (a) has a structure in which a single flow path 11 is formed by butt-welding the ends of both ends 22 of the metal plate 21, so that the joint area is small. For this reason, the pressure resistance becomes small, which causes a problem in strength such that the width dimension of the flat tube 2a cannot be increased. In addition, since the roll forming process is performed on the material of the long metal plate 21, there is a problem that the processing cost of the flat tube 2a becomes high.

In the flat tubes 2b and 2c of the second and third examples shown in FIGS. 7 (b) and 7 (c), the raw materials of the metal plates 23 and 26 are subjected to roll forming and further complicated bending, L-shaped bend 2 at the center in the width direction
Since it is reinforced with 5,27, there is little problem in strength, but there is a problem that the processing cost becomes high. On the contrary, L for brazing
The bent portions 25 and 27 are flat tubes 2b and 2 respectively.
Since it is located in the central portion in the width direction of c, the flux for brazing after the temporary assembly of the heater core in which the flat tubes 1 and the corrugated fins 3 are alternately arranged is hard to flow to the brazing portion, and the brazing defect is likely to occur. There is a defect.

[0010]

DISCLOSURE OF THE INVENTION In order to solve the above-mentioned problems of the flat tubes used in the related art, the flat tubes forming the flow passages inside have side surfaces formed at both ends thereof. Since it is formed by two U-shaped cross-section plates that are superposed, the width dimension can be increased, the joint area can be increased, the pressure resistance can be increased, the heat transfer efficiency can be improved, and the flat tube can be manufactured by pressing. In addition, the processing cost can be reduced, and by making the brazing part on both ends of the flat tube, the brazing flux can easily go to the brazing part, improving the brazing property and facilitating the work. It is an object of the present invention to provide a highly reliable flat tube for a heat exchanger in which brazing failure does not easily occur and a heat exchanger using the flat tube.

[0011]

Therefore, the flat tube for a heat exchanger according to the first aspect of the present invention has the following means.

(1) A flat tube in which a flow path is formed in the inside of which the cross-sectional shape is flat and heat exchange between a fluid flowing through the flow path and a fluid flowing outside the flow path is made of a metal plate. It is composed of two U-shaped cross-section plates whose side portions are formed by bending both ends, and the opening sides formed in the two U-shaped cross-section plates face each other, and When the side surface portion is inserted inside the side surface portion of the U-shaped cross-section plate on the other side, the flow path is formed inside by joining the joint portions formed by the side surface portions that are superposed on each other. It is preferable that both ends of the metal plate forming the side surface are bent at 90 °, but the present invention is not limited to this.

(A) As a result, the processing of the metal plate forming the flat tube does not depend on roll forming or the like, and complicated bending processing is not required, and it can be easily performed by press working. Combined with simplification, the processing cost will be low. In addition, since the flat tube is formed by welding or brazing the joint portion in which the side surface portions formed on the two U-shaped cross-section plates are overlapped with each other, the side surface height is set to an appropriate size. By adjusting the area of the joint portion, the pressure resistance strength can be made excellent. Also, the joint becomes the end of the flat tube, and since the joint area can be adjusted, the work of joining the flat tube after temporary assembly of the heater core can be facilitated, and the brazing flux etc. can easily flow to the joint. Therefore, it is possible to prevent the occurrence of defective joining.

The flat tube for a heat exchanger according to the second aspect of the present invention has the following means in addition to the above-mentioned means (1).

(2) Of the two U-shaped cross-section plates forming the flat tube, the width in the fluid flow direction, which is the length between the side surface portions formed at both ends of one U-shaped cross-section plate, The width of the metal plate is made twice as long as the width of the other U-shaped cross-section plate, and the height of the side surface portion formed on one U-shaped cross-section plate is formed on the other U-shaped cross-section plate. The height of the metal plate is made higher than the height of the side surface, and the opening sides of the U-shaped cross-section plates face each other, and the other U-shaped cross-section plate is inserted inside the side surface of one U-shaped cross-section plate. The flow paths are formed inside by laminating and connecting the side surfaces of each other.

(B) As a result, in addition to the above (a), 2
The U-shaped cross-section plates are nested, and the side parts are stacked, and the shape can be stably maintained until the brazing of the joint part, which is performed at the same time as brazing of the heat exchanger core,
Easier to manufacture flat tubes.

The flat tube for a heat exchanger according to the third aspect of the present invention has the following means in addition to the above-mentioned means (1).

(3) The height of each of the two U-shaped cross-section plates forming the flat tube is higher than the height of the side surface formed at one end of each metal plate, rather than the height of the side surface formed at the other end. Are formed in a substantially identical shape that is elevated by the thickness of one metal plate, and the side surfaces with low height provided on both U-shaped cross-section plates are placed inside The opening sides of the cross-section plates are opposed to each other, and the cross-section plates are inserted along the side surfaces with high heights provided on the U-shaped cross-section plates. Shall be formed.

(C) As a result, in addition to the above (a), the flat tube can be formed of one type of U-shaped cross section plate, which facilitates the production of the U-shaped cross section plate and the flat tube assembling work. At this time, the work of selecting the U-shaped cross-section plate becomes unnecessary, and the assembly work time can be shortened.

The flat tube for a heat exchanger according to the fourth aspect of the present invention has the following means in addition to the above-mentioned means (2) or (3).

(4) The U-shaped cross-section plate forming the flat tube is provided on the inner side, which is the flow path side of the flat surface formed in the fluid flow direction of the side surfaces provided at both ends of the metal plate, of the fluid in the flow path. A group of protrusions orthogonal to the flow direction was provided. Note that the height of the protrusions that project from the inside of the flat surface portion to the flow path side may be determined in consideration of the increase in the fluid resistance in the flow passage due to the installation of the projections and the heat transfer capacity required for the heat exchanger. .

(D) As a result, in addition to the above (b) and (c), the fluid flowing in the flow passage is promoted to transition to a turbulent state by the projection group, and the thermal conductivity is improved. By adding the heat transfer surface of the group, the heat transfer area in the flow path is increased, and the heat exchange performance can be improved.

The flat tube for a heat exchanger of the fifth aspect of the present invention has the following means in addition to the above-mentioned means (2) or (3).

(5) The U-shaped cross-section plate forming the flat tube is protruded inward from the flat portion toward the flat portion flow path side formed in the fluid flow direction of the side surface portions provided at both ends of the metal plate. The corrugated portion is provided so as to be orthogonal to the flow direction of the fluid in the flow channel.

(E) As a result, in addition to the above-mentioned (b) and (c), the fluid flowing in the flow passage has an increased heat transfer area in the flow passage due to the addition of the heat transfer surface due to the formation of the corrugated portion. However, the heat exchange performance can be improved. Further, the corrugated portion can be easily formed by press working, and the working cost can be reduced as compared with the fourth embodiment.

Further, the heat exchanger of the present invention using the flat tube for the heat exchanger has the following means.

(6) A flat tube for a heat exchanger comprising any of the flat tubes for a heat exchanger of (1) to (5) described above is arranged in the width direction of both side surfaces along the flow direction of the air flowing therethrough. , Multiple rows are arranged at equal intervals in the lateral direction orthogonal to the air flow direction, and both ends are fixed to the respective side surfaces of the heat exchanger flat tubes arranged adjacent to each other, and between the side surfaces of the heat exchanger flat tubes. The corrugated fins installed on the floor shall be installed.

(F) As a result, in addition to the above (a) to (e), both side surfaces of the flat tube for the heat exchanger are arranged in the air flow direction for heat exchange, and the widthwise dimension of both side surfaces in the air flow direction is set. Since it becomes larger, corrugated fins are formed in the direction orthogonal to the air flow direction and are arranged substantially parallel to the air flow direction, and the corrugated fins that connect both ends to both sides of the flat tube for the heat exchanger are arranged in the air flow direction. Since it is long and the connecting area with both side surfaces of the flat tube for the heat exchanger can be increased, it can be structurally made high in strength and compact, inexpensive, and highly efficient in heat transfer. Furthermore, the joint part of the flat tube for the heat exchanger becomes the end of the heat exchanger that is easily accessible, and the joint area can be adjusted, which facilitates the joint work of the flat tube for the heat exchanger after the heater core is temporarily assembled, In addition, the brazing flux or the like easily goes around to the joint portion, and it is possible to make the joint highly reliable with less occurrence of joint failure.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a flat tube for a heat exchanger and a heat exchanger using the same according to the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a flat tube as a first embodiment of a flat tube for a heat exchanger of the present invention.

As shown in the figure, in the flat tube 101 of this embodiment, both end portions of a metal plate such as copper or aluminum are bent by 90 ° by press working, and the side surface portion 1 is formed at both end portions.
The width between the U-shaped cross-section plate 102 formed with 04 and the side surface portion 104 of the U-shaped cross-section plate 102 is reduced by twice the thickness of the metal plate, and both ends are pressed. Bend 90 ° with the side part 10
U-shaped cross-section plate with another U-shaped cross-section plate 103 having side surfaces 105 having a height smaller than the height of 4 by the thickness of the metal plate at both ends, and having a reduced height and width. The opening 103 is inserted toward the opening of the U-shaped cross-section plate 102, and the cooling water passage 101a is formed by fitting and coupling. In addition, the side surface portion 105 and the side surface portion 10 arranged inside the side surface portion 104.
The brazing of the flat tube 101 for coupling with the No. 4 is performed at the same time as the brazing of the heat exchanger core for coupling the corrugated fins 3 to the outer surface of the flat tube 101.

As described above, the flat tube 101 of this embodiment is fitted so that the openings of the two types of U-shaped cross-section plates 102 and 103 having different widths and heights of the side surfaces in the air flow direction are opposed to each other. In addition, since the side surface portions 104 and 105 formed at both end portions are superposed on each other and the superposed portions are formed by brazing and coupling, the joint area becomes large and the breakdown voltage is increased. It is possible to improve the strength and obtain a flat tube having a large width dimension.

Further, since the U-shaped cross-section plates 102 and 103 formed by bending both ends by 90 ° can be manufactured by press working which is easy to process, the processing cost is reduced and the brazed portion is formed on the side surface portion 104 and 103. Since 105 is the both ends of the flat tube 101 that is superposed on each other,
There is also an advantage that the flux for brazing easily flows to the joint portion, the brazing property is improved, and brazing failure does not easily occur.

Next, FIG. 2 is a cross-sectional view showing a flat tube as a second embodiment of the flat tube for a heat exchanger of the present invention. As shown in the figure, in the flat tube 201 of the present embodiment, one end portion of a metal plate such as copper or aluminum is bent by press working, and the side surface portion 203a is formed at one end portion.
And a side surface portion 203b having a height smaller than the height of the side surface portion 203a by the thickness of the metal plate at the other end portion of the metal plate,
Similarly, it is composed of two U-shaped cross-section plates 202 formed by pressing, and the openings of the two U-shaped cross-section plates 202 are opposed to each other, and the side surface 203a having a high height is located outside the side surface 203b having a low height. , And the two U-shaped cross-section plates are fitted and joined together to form the cooling water passage 201a therein.

Further, the side surface portion 2 having a low height to be arranged inside
The brazing of 03b and the high side surface portion 203a arranged on the outer side is similar to that of the first embodiment.
The heat exchanger core for joining the corrugated fins 3 to the outer surface of 01 is brazed at the same time.

As described above, the flat tube 201 according to the present embodiment is formed of one type in which the side surfaces 203a and 203b having different heights are formed at both ends of the metal plate by the thickness of the metal plate. The two U-shaped cross-section plates 202 are fitted to each other, the side surface portions 203a and 203b are overlapped with each other, and the structure is formed by brazing the overlapped portions, so that the joint surface becomes large. The pressure resistance is improved, and a wide flat tube can be obtained.

Further, since the U-shaped cross-section plate 202 can be manufactured by press working, which is easy to process, like the U-shaped cross-section plates 102 and 103 of the first embodiment, the processing cost is reduced and the brazed portion is formed. Since it is at both ends of the flat tube 201, there is an advantage in that the flux for brazing easily flows to the joint portion, the brazing property is improved, and brazing failure is less likely to occur.

Next, FIG. 3 is a transverse sectional view showing a flat tube as a third embodiment of the flat tube for a heat exchanger of the present invention.

As shown in the figure, the flat tube 301 of the present embodiment is a U-shaped cross-section plate 10 of the first embodiment.
U-shaped cross-section plate 30 manufactured in the same manner as 2, 103
Protrusions 306 of appropriate height on the inside of the flat surface of 2,303
However, the protrusions 306 are formed inside by inserting the openings of the U-shaped cross-section plate 303, which are formed by press working or the like, and whose height and width are reduced, toward the openings of the U-shaped cross-section plate 302 and fitting them together. The cooling water flow path 301a is formed.

The flat tube 301 of the present embodiment has the same structure as the flat tube 101 of the first embodiment, and the flow passage 301a is formed on the surface of the cooling water passage 301a formed inside the flat tube 301. Since the projection group 306 having an appropriate height, which is determined in consideration of the internal resistance and the amount of heat transfer, is formed by press working, in addition to the effect and usefulness described in the first embodiment, the projection When the cooling water flows in the group 306, turbulence is generated in the flow to promote heat transfer, and the inner surface area of the flow path 301a is further increased to increase the heat transfer area to improve heat exchange performance. There is an advantage that

The projection group 306 provided in this embodiment is the U-shaped cross-section plate 20 of the second embodiment.
Even if it is provided inside the plane portion of No. 2, the same effect can be obtained.

Next, FIG. 4 is a cross-sectional view showing a flat tube as a fourth embodiment of the flat tube for a heat exchanger of the present invention. As shown in the figure, the flat tube 401 of the present embodiment is similar to the U-shaped plate 10 of the first embodiment.
Similarly to Nos. 2 and 103, a wavy portion 406 having an appropriate height, which is determined in the same manner as in the third embodiment, is provided on the plane portion of the U-shaped cross-section plates 402 and 403 on which the side surface portions 404 and 405 are formed. Formed by pressing, etc., height,
By inserting the opening of the U-shaped cross-section plate 403 whose width is reduced toward the opening of the U-shaped cross-section plate 402 and fitting them together, the cooling water flow path 301 in which the corrugated portion 406 having an appropriate height is formed is formed. I am trying to form.

The flat tube 401 of this embodiment has the same structure as the flat tube 101 of the first embodiment, and has an appropriate height on the surface of the cooling water passage 401a formed inside the flat tube 401. Since the wavy portion 406 of No. 1 has a structure formed by press working, in addition to the effect and usefulness described in the first embodiment, the inner surface area of the flow channel 401a increases and the heat transfer area increases, so that heat exchange is performed. There is an advantage that the performance can be improved. In addition, even if the corrugated portion 406 provided in the present embodiment is provided inside the flat portion of the U-shaped cross-section plate 202 of the second embodiment as in the third embodiment, the same effect is obtained. Is what you get.

Next, the embodiment of the heat exchanger using the flat tube for heat exchanger of the present invention is the first embodiment described above.
Either the flat tube 101 of the embodiment or the flat tube 401 of the fourth embodiment is used instead of the flat tube 2 and is similar to that shown in FIG. 5 described above.

In the heat exchanger of the present embodiment thus configured, the flat tubes 101 to 40 constituting the heater core 1
Both side surfaces of No. 1 are arranged in the direction of air flow for heat exchange, the width dimension of both side surfaces in the air flow direction increases, and a corrugation is formed in a direction orthogonal to the air flow direction to The corrugated fins, which are arranged substantially parallel to each other and whose both ends are connected to both sides of the flat tube for heat exchanger, are long in the air flow direction, and the connection area with both sides of the flat tube for heat exchanger can be increased, resulting in structurally high strength. In addition, it can be made compact, inexpensive, and highly efficient in heat transfer. Furthermore, the joint part of the flat tube for heat exchanger becomes the easily accessible end of the heat exchanger, and the joint area can be adjusted, which facilitates the work of joining the flat tube for heat exchanger after the temporary assembly of the heater core. In addition, the brazing flux or the like is likely to flow around the joint portion, resulting in high reliability with less occurrence of joint failure.

[0045]

As described above, in the flat tube heat exchanger for heat exchangers of the present invention, the flat tubes for exchanging heat between the air and the cooling water are bent to form side surfaces by bending both ends of the metal plate. When two U-shaped cross-section plates are inserted into the inside of the other U-shaped cross-section plate with the openings of the U-shaped cross-section plates facing each other, when they are inserted inside the other U-shaped cross-section plate, they flow inside. It is assumed that a road is formed.

As a result, the flat tube does not require complicated bending of the metal plate and can be easily manufactured by press working, and the working cost can be reduced in combination with the simplification of the shape. In addition, the joint portions in which the side surface portions of the two U-shaped cross-section plates are overlapped with each other can be formed by joining by brazing, etc., and the pressure resistance strength can be made excellent by adjusting the joint portion area, and the width dimension can be increased. Further, the joint becomes an easily accessible end of the heat exchanger, and the joint area can be adjusted, so that the joint after the heater core is temporarily assembled becomes easy, and the flux such as the brazing flux can easily reach the joint. It is possible to prevent the occurrence of defective joining.

According to the present invention, the width between the side surfaces of one of the U-shaped cross-section plates of the two U-shaped cross-section plates is made twice as long as the width of the metal plate than the width of the other U-shaped cross-section plate. , The height of the side surface of one U-shaped cross-section plate is made higher than the height of the side surface of the other U-shaped cross-section plate by the plate thickness of the metal plate, and the openings are opposed to each other, and the other U-shaped cross-section plate Was inserted into one of the U-shaped cross-section plates, and the side surfaces were overlapped to form a flow path inside.

As a result, the two U-shaped cross-section plates are
The nesting side surfaces can be overlapped and the shape can be stably maintained up to brazing of the heat exchanger core and brazing of the joint portion at the same time, and the flat tube can be easily manufactured.

The present invention also forms a flat tube 2
The U-shaped cross-section plates have a substantially same shape in which the height of the side surface formed at the other end is higher than the height of the side surface formed at one end of the metal plate by the thickness of one metal plate. The side surfaces having a low height are arranged inside and the openings are inserted so as to face each other, and the side surfaces having different heights are overlapped to form a flow path inside.

As a result, the flat tube can be formed of one type of U-shaped cross-section plate, and the work of selecting the U-shaped cross-section plate at the time of manufacturing and assembling the U-shaped cross-section plate becomes unnecessary.
Manufacturing cost can be reduced.

Further, according to the present invention, the U-shaped cross-section plate forming the flat tube is provided with a group of protrusions inside the flat surface portion between the side surface portions provided at both ends of the metal plate so as to be orthogonal to the flow direction of the cooling water. I was supposed to.

As a result, the cooling water flowing in the flow path is
The transition to the turbulent state is promoted by the time of projection, and the thermal conductivity is improved, and the addition of the heat transfer surface of the projection group increases the heat transfer area in the flow path, so that the heat exchange performance can be improved.

Further, in the present invention, the U-shaped cross-section plate forming the flat tube is protruded inward from the flat surface portion toward the flat surface channel between the side surface portions provided at both ends of the metal plate to form a corrugated portion. It is supposed to be provided.

As a result, the corrugated portion can be formed at a low processing cost, and the cooling water flowing in the flow passage is increased in heat transfer area in the flow passage due to the addition of the heat transfer surface to perform heat exchange. Exchange performance can be improved.

Further, the heat exchanger using the flat tube for the heat exchanger of the present invention is arranged in the width direction of both side surfaces in the direction of the flow-through air, and is arranged in a plurality of rows at equal intervals in the lateral direction orthogonal to the air flow direction. A flat tube for a heat exchanger having a flow passage formed therein, and a corrugated fin having both ends fixed to the side surfaces of an adjacent flat tube for the heat exchanger and erected between the side surfaces.

The flat tube can be easily processed, the processing cost is low in combination with the simplification of the shape, the pressure resistance strength is excellent by adjusting the joint area, and the widthwise dimension in the air flow direction is large. As a result, since the size of connection with the corrugated fins is increased, the strength and compactness of the heat transfer can be improved.

[Brief description of drawings]

FIG. 1 is a first embodiment of a flat tube for a heat exchanger according to the present invention.
A cross-sectional view showing a flat tube as a form,

FIG. 2 is a second embodiment of the flat tube for a heat exchanger of the present invention.
A cross-sectional view showing a flat tube as a form,

FIG. 3 is a third embodiment of the flat tube for a heat exchanger of the present invention.
A cross-sectional view showing a flat tube as a form,

FIG. 4 is a fourth embodiment of the flat tube for a heat exchanger of the present invention.
A cross-sectional view showing a flat tube as a form,

FIG. 5 is a perspective view showing an overall appearance of a heater core used in a hot water heating system for a vehicle;

6 is a partially enlarged view of a heater core conventionally used in the vehicle hot water heating system shown in FIG.

7 is an enlarged view of a cross-sectional shape of a flat tube used in the heater core shown in FIG. 6, FIG. 7 (a) showing a first example, and FIG. 7 (b) showing a second example. FIG. 7C is a diagram showing a third example.

[Explanation of symbols]

1 Heater Cores 2, 2a, 2b, 2c Flat Tube 3 Corrugated Fins 4 Upper Tank 5 Lower Tank 6 Header Plate 7 Header Plate 8 Cooling Water Inlet Pipe 9 Cooling Water Outlet Pipe 10 Air Flow Direction 11 Channels 21, 23, 26 Metal Plate 22, 24 Ends 25, 27 L-shaped bent portion 28 Inner column portion 101, 201, 301, 401 Flat tube 101a, 201a, 301a, 401a Flow path 102, 103, 202, 302, 303, 402, 4
03 U-shaped cross-section plates 104, 105, 203a, 203b, 304, 30
5,404,405 Side part 306 Protrusion group

Claims (6)

[Claims] 1. A flat tube for a heat exchanger, which has a flat cross-sectional shape and which forms a flow passage for allowing a fluid to flow therethrough, wherein the flat tube forming the flow passage has side surfaces formed by bending both ends of a metal plate. It is formed by two U-shaped cross-section plates, the opening sides of which are opposed to each other, and the side surface portion of the U-shaped cross-section plate on one side is inserted inside the side surface portion of the U-shaped cross-section plate on the other side and they are overlapped with each other. A flat tube for a heat exchanger, characterized in that the flow path is formed inside. 2. The U-shaped cross-section plate has a width in the air flow direction of one of the U-shaped cross-section plates longer than the width of the other U-shaped cross-section plate by twice the plate thickness of the metal plate, It is formed by two U-shaped cross-section plates in which the height of the side surface portion of one of the U-shaped cross-section plates is higher than the height of the side surface portion of the other U-shaped cross-section plate by the plate thickness of the metal plate. , The side faces of the other U-shaped cross-section plate are inserted inside the side faces of one of the U-shaped cross-section plates so that their opening sides are opposed to each other, and the side faces of the U-shaped cross-section plates are overlapped and joined to each other to form the flow path inside. The flat tube for a heat exchanger according to claim 1, wherein 3. The U-shaped cross-section plate has substantially the same height as that of the side surface formed at one end of the metal plate, and the height of the side surface at the other end is increased by the plate thickness of the metal plate. It consists of two U-shaped cross-section plates, and the side parts with a low height are placed inside, the opening sides are opposed to each other, and they are inserted into each other, and the side parts with different heights are superposed and joined to each other. The flat tube for a heat exchanger according to claim 1, wherein a flow path is formed. 4. The U-shaped cross-section plate is provided with a group of protrusions inside a flat surface portion formed between the side surface portions so as to be orthogonal to the flow direction of the fluid in the flow path. The flat tube for a heat exchanger according to claim 2 or 3. 5. The U-shaped cross-section plate is provided with a corrugated portion projecting inward from the planar portion and orthogonal to a flow direction of a fluid in a flow channel, on a planar portion formed between the side surface portions. The flat tube for a heat exchanger according to claim 2 or 3, characterized in that 6. A flat tube for a heat exchanger according to any one of claims 1 to 5, wherein the flat tubes adjacent to each other are arranged in a plurality of rows at equal intervals along the width direction of both side surfaces of the flat tube for a heat exchanger in the direction of air flow. A heat exchanger characterized in that corrugated fins are arranged between both side surfaces of the heat exchanger.