JPH10288491A - Flat tube for heat exchanger and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat tube for heat exchanger that maintains uniform and superior heat transfer characteristics and can reduce the number of parts and cost, and provide further its manufacturing method. SOLUTION: A flat tube 1 comprises a flat tube 10 where a section shape is flat and at the same time a fluid passage 15 is provided inside and an inner fin 2 that is placed in the fluid passage 15 of the flat tube 10 to disturb the flow of a fluid. The inner fin 2 consists of one rib body 20 with a plurality of ribs 21 being arranged obliquely in parallel and at the same time is constituted by folding the rib body 20 doubly so that the ribs 21 cross each other. Also, the inner fin 2 has an engagement part 26 being provided along the longitudinal direction. On the other hand, the flat tube 10 has a positioning part that can be engage with the engagement part 26. The inner fin 2 allows the engagement part 26 to be engaged with the positioning part 16 and is arranged in the flat tube 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a flat tube in a laminated heat exchanger and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a heat exchanger for a vehicle, a laminated heat exchanger in which flat tubes constituting a refrigerant passage and fins for transferring heat to air are alternately laminated has been used. I have. The flat tube in such a stacked heat exchanger may have a flat cross section and a large number of ribs provided in a fluid passage inside the flat tube in order to promote heat transfer from the refrigerant.

[0003] For example, there is a type in which a metal plate constituting a flat tube is pressed so that a wall itself of the flat tube protrudes inward to integrally form a rib. Further, as disclosed in JP-A-6-74678, there is a flat tube 9 of a type in which an inner fin separately formed is inserted and arranged inside a flat tube.

As shown in FIG. 11, a flat tube 9 is
Separately from the flat tube 91 having a flat shape, two rib bodies 92 each having a large number of ribs 921 are prepared and used as inner fins 93 by overlapping them so that the ribs 921 cross each other. The inner tube 93 is inserted into the flat tube 91 to form the flat tube 9. This flat tube 9 can greatly improve the heat transfer efficiency as compared with a flat tube of a type in which ribs are integrally provided by the above-described press working.

[0005]

However, the conventional flat tube 9 has the following problems. That is, by using the inner fins 93, the heat transfer efficiency of the flat tube 9 can be improved as compared with the flat tube of the press processing type, but the number of parts increases and the cost increases.

Further, in the flat tube 9, the width of the inner fin 93 may be sufficiently smaller than the width of the fluid passage in order to improve the insertability of the inner fin 93 during its manufacture. However, in this case, there is a problem that after the inner fin 93 is inserted, the inner fin 93 is arranged to be biased to one side in the fluid passage. This offset arrangement of the inner fins may lead to an offset of heat transfer with the fluid.

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and has a flat tube for a heat exchanger, which can reduce the number of parts and reduce costs while maintaining uniform and excellent heat transfer characteristics. It is intended to provide a manufacturing method thereof.

[0008]

According to a first aspect of the present invention, there is provided a flat tube forming a fluid passage for a heat exchanger, wherein the flat tube has a flat cross section and has a fluid passage therein. An inner fin inserted into the fluid passage of the flat tube to disturb the flow of fluid, wherein the inner fin is a single rib having a plurality of ribs arranged obliquely parallel to a longitudinal direction of the flat tube; And the ribs are double folded so that the ribs intersect each other. The inner fin has an engaging portion provided along the longitudinal direction. On the other hand, the flat tube has a positioning portion engageable with the engaging portion, and the inner fin is disposed in the flat tube by engaging the engaging portion with the positioning portion. Specially In heat exchanger flat tube to.

The most remarkable point in the present invention is that the inner fin is formed by folding the single rib body so as to be doubled, and the positioning of the inner fin and the flat tube is performed by the following method. This is achieved by the engagement between the engaging portion and the positioning portion.

As the flat tube, those having various structures can be applied as long as they have a fluid passage having a flat cross section for inserting and disposing the inner fin. For example, various types of flat tubes, such as those formed by joining two metal plates by brazing or the like as in the related art and those formed by deforming a round tube into a flat shape, can be applied.

Further, the inner fin is constructed by folding one rib body twice as described above. The folding direction is preferably along a folding line parallel to the longitudinal direction. In addition, there are various methods of folding, such as a method of folding in two along the folding line at the center in the width direction, and a method of folding in two at both ends toward the center along two left and right folding lines. Can be.

Further, the inner fin is provided with an engaging portion along its longitudinal direction, that is, along the axial direction of the flat tube, while the flat tube is provided with a positioning portion capable of engaging with the engaging portion. . The engaging portion and the positioning portion can be constituted by, for example, a combination of a groove and a projection, or a combination of a projection and a groove.

Next, the operation of the present invention will be described. The inner fin of the flat tube of the present invention is constructed by using one rib body and folding it as described above. For this reason, an inner fin having the same function as the conventional case where two ribs are stacked can be formed despite the fact that the number of components is one.

That is, the rib body has a large number of ribs provided obliquely in the longitudinal direction. Therefore, when this is folded, it is possible to obtain a state in which the ribs cross each other, as in the case where the rib bodies having the ribs inclined in the opposite direction are overlapped. Therefore, the inner fin in the present invention can maintain the function of sufficiently disturbing the flow of the fluid as in the related art.

[0015] The inner fin is provided with the engaging portion, and the flat tube is provided with the positioning portion. Therefore, when the inner fin is inserted and arranged in the flat tube, the positioning in the width direction can be performed easily and reliably. Therefore, the inner fin in the fluid passage is
At any position in the longitudinal direction, it is stably arranged at the central portion, and uniform heat transfer characteristics can be maintained.

As described above, according to the present invention, it is possible to obtain a flat tube for a heat exchanger that can reduce the number of parts and reduce the cost while maintaining uniform and excellent heat transfer characteristics.

Next, as in the second aspect of the present invention, the engaging portion of the inner fin is provided between the opposite ends by bending both ends of the rib body from right and left along the longitudinal direction and facing each other. It is preferable that the positioning portion of the flat tube be formed by a projection provided along the longitudinal direction on the inner surface of the tube wall of the flat tube.

That is, the inner fin is formed by folding both ends toward the center along two bending lines parallel to the longitudinal direction. Further, the folded width is set to a width that forms the gap with a constant width without the two ends being in contact with each other. Thus, the groove-shaped gap is formed in the inner fin. Therefore, there is no need to provide a special process for forming the engagement portion in the inner fin, and the cost can be further reduced.

According to a third aspect of the present invention, the flat tube is a welded tube, and the positioning portion is formed of a weld bead provided on an inner surface of a tube wall of the welded tube along a longitudinal direction thereof. Is preferred. Thus, the projection corresponding to the gap can be easily obtained by leaving the weld bead of the welded pipe without providing a special process. Therefore, the manufacturing cost of the flat tube can be reduced, and the cost of the entire flat tube can be further reduced.

Next, there is the following invention as a method of manufacturing the above excellent flat tube. That is, a flat tube having a flat cross-sectional shape and having a fluid passage therein, and an inner fin inserted into the fluid passage of the flat tube and disturbing the flow of the fluid, as in the fourth aspect of the invention. A method for producing a flat tube for a heat exchanger, comprising: first preparing a round tube having a circular cross section having a protrusion along the longitudinal direction on the inner surface of the tube wall, and connecting the round tube to the tube wall facing the protrusion. The above-mentioned flat tube having a flat cross section is produced by pressing and deforming so as to approach the above-mentioned condition. On the other hand, one rib body having a plurality of ribs arranged obliquely parallel to the longitudinal direction of the flat tube is prepared.
An inner fin is formed by bending both ends of the rib body from the left and right along the longitudinal direction and providing a gap between the facing opposite ends, and then forming the inner fin with the gap engaged with the projection. There is a method for manufacturing a flat tube for a heat exchanger, wherein the inner fin is inserted into a flat tube and then both are integrally joined.

The most remarkable point in this manufacturing method is that the flat tube is manufactured using the round tube having the projections, and the flat tube is folded using the single rib body to form the inner fin having the gap. It is to produce.
The pressing deformation of the round tube can be performed by roll forming or press forming. The bending of the rib body can also be performed by roll forming or press forming.

Further, the flat tube and the inner fin can be integrally joined by, for example, brazing.
In this case, brazing can be easily performed by using a clad material having a brazing material as a skin material as a material of the flat tube and the inner fin.

Next, the operation of the present manufacturing method will be described. In this manufacturing method, the flat tube is manufactured by pressing and deforming the round tube using the round tube. Therefore, the number of components can be reduced as compared with the conventional case where two plates are superposed and manufactured. Further, the inner fin can be formed by the single rib body, and in this case also, the number of parts can be reduced as compared with the conventional case.

The flat tube is provided with the protrusion, while the inner fin is provided with the gap. Therefore, when the inner fin is inserted into the flat tube, the inner fin can be inserted into the flat tube while the gap is engaged with the projection. Thereby, the position of the inner fin arranged in the flat tube in the width direction can be easily and reliably positioned.

Further, the position of the inner fin which is securely positioned and inserted is maintained in the subsequent integral joining. Therefore, the position of the inner fin in the fluid passage is stable, regardless of the position of the obtained flat tube in the longitudinal direction, so that the heat transfer characteristics of the fluid can be maintained uniformly.

Therefore, according to the present manufacturing method, it is possible to provide a method for manufacturing a flat tube for a heat exchanger which can reduce the number of parts and reduce costs while maintaining uniform and excellent heat transfer characteristics. it can.

According to a fifth aspect of the present invention, the round pipe is a welded pipe, and the projection is formed of a weld bead provided on an inner surface of a pipe wall of the welded pipe along a longitudinal direction thereof. Is preferred. Accordingly, the welding bead can be effectively used by leaving the welding bead without providing the projection of the round pipe. Therefore, the manufacturing cost can be reduced.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 A flat tube for a heat exchanger and a method for manufacturing the same according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, a flat tube 1 for a heat exchanger of this embodiment has a flat cross section and a fluid passage 1 therein.
5 and an inner fin 2 inserted into the fluid passage 15 of the flat tube 10 to disturb the flow of the fluid.

As shown in FIGS. 1 and 4, the inner fin 2 is formed of a single rib body 20 having a plurality of ribs 21 arranged obliquely parallel to the longitudinal direction of the flat tube 10. As shown in FIG. 1, the rib body 20 is folded twice so that the ribs 21 cross each other.

The inner fin 2 has an engaging portion 26 provided along the longitudinal direction, while the flat tube 10 has a positioning portion 16 engageable with the engaging portion 26. As shown in FIG. 1, the inner fin 2 is disposed in the flat tube 10 by engaging the engaging portion 26 with the positioning portion 16.

As shown in FIG. 1, the engagement portion 26 of the inner fin 2 in this embodiment is formed by a gap provided between both ends of the rib body 20 by bending both ends of the rib body 20 from the left and right along the longitudinal direction. It is configured.
The flat tube 10 is a welded tube, and the positioning portion 1
Numeral 6 is a weld bead provided on the inner surface 12 of the pipe wall of the weld pipe along the longitudinal direction.

In manufacturing the flat tube 1, first, the flat tube 10 and the inner fin 2 are separately manufactured. In producing the flat tube 10, as shown in FIG. 2, a welded round tube 19 having a circular cross section and having a weld bead 16 along the longitudinal direction on the inner surface 12 of the tube wall.
Prepare The welded round pipe 19 of this embodiment uses a clad material in which a brazing material is clad on the inner surface thereof.

Next, the welded round pipe 19 is pressed and deformed so that the weld bead 16 approaches the pipe wall facing the welded round pipe 19 to form the flat pipe 10 having a flat cross section. Specifically, FIG.
As shown in (c), this is performed by three stages of roll forming.
That is, a pair of first pipe rolls 51 whose groove shapes are slightly elliptical, a pair of second tube rolls 52 whose hole shapes are almost elliptical, and a desired flat shape of the hole. The welded round pipe 19 is sequentially formed by using the third hole type roll 53 shaped into a shape.

Thus, the welded round pipe 19 is formed into the flat pipe 10 through the state of the first intermediate pipe 191 and the second intermediate pipe 162. Also, when the flat tube 10 is formed, as shown in FIG.
As shown in (a) to (c), the welding bead 16 was always positioned at the upper center. Thereby, the obtained flat tube 1
0 was obtained with the weld bead placed in the center of the flat part. Further, as shown in FIG. 3C, the fluid passage 15 is formed inside the flat tube 10.

Next, in manufacturing the inner fin 2, as shown in FIG. 4, one rib body 20 having a plurality of ribs 21 arranged obliquely parallel to the longitudinal direction of the flat tube 10 is prepared. Note that the rib body 20 of this example is formed by using a clad material having brazing materials arranged on both surfaces and punching the clad material with a press.

Next, the inner fin 2 is manufactured by bending both ends of the rib body 20 from the left and right along the longitudinal direction and providing a gap 26 between the facing opposite ends. More specifically, as shown in FIGS. 5 (a) to 5 (d), this is performed by four-stage roll forming. That is, a pair of first fin rolls 61 each having a hole shape slightly raised at both ends, a pair of second fin rolls 62 each having a hole shape obtained by forming both ends at a right angle, and an acute angle at both ends. The rib body 20 is sequentially formed by using the third fin roll 63 having the hole shape described above and the fourth fin roll 64 having the hole shape corresponding to the thickness of the rib body 20 folded in half.

As a result, the rib body 20 is formed as shown in FIGS.
As shown in (d), the first intermediate body 201 whose both ends are bent at an obtuse angle, and the second intermediate body 20 whose both ends are bent at a right angle.
2. The inner fin 2 is formed through the state of the third intermediate body 203 having both ends bent at an acute angle. The rib body 20
In the molding of, the bending width at both ends was set to a width smaller than １ ／ of the entire width. Thereby, as shown in FIGS. 1 and 5, the gap 26 can be formed in the inner fin 2.

Next, as shown in FIG. 6, the inner fin 2 is inserted and arranged in the fluid passage 15 of the obtained flat tube 10. At this time, the inner fin 2 is inserted into the flat tube 10 with the gap 26 engaged with the welding bead 16. As a result, the inner fins 2 are arranged in the flat tube 10 while keeping the position of the flat tube 10 in the fluid passage 15 in the width direction constant.

Next, the flat tube 10 containing the inner fin 2 is entirely heated. Thereby, inner fin 2
The inner fin 2 and the flat tube 10 are brazed integrally by the action of the brazing material. As a result, as shown in FIG. 1, a flat tube 1 in which the inner fin 2 is integrated is obtained.

Next, the operation of this embodiment will be described. The inner fin 2 of the flat tube 1 of the present embodiment is configured by using one rib body 20 and folding the same. In addition, in manufacturing the inner fin 2, the inner fin 2 can be manufactured continuously and with high efficiency by the roll forming.
Therefore, the production cost of the inner fin 2 can be achieved from both the reduction of the number of parts and the rationalization of the process.

In this embodiment, the flat tube 10 is manufactured by using a welded round tube 19. Therefore, flat tube 1
No. 0 can be manufactured continuously and with high efficiency by forming the welded round tube 19 by the roll forming. The projections 16 on the flat tube 10 include:
The weld bead left in the welded round pipe 19 is used as it is. Therefore, there is no need to provide a special projection forming step or the like. Therefore, the manufacturing cost of the flat tube 10 can be reduced by rationalizing the molding process.

Further, the flat tube 1 of this embodiment is inserted into the flat tube 10 with the gap 26 in the inner fin 2 engaged with the weld bead 16. Therefore, the inner fin can be easily and reliably positioned at the optimum position in the fluid passage 15 of the flat tube 10. Therefore, the flat tube 1 of the present example can stably secure the position in the width direction of the inner fin 2 at any position in the longitudinal direction, and can maintain uniform heat transfer characteristics.

As described above, according to this embodiment, it is possible to obtain a flat tube for a heat exchanger and a method for manufacturing the same, which can reduce the number of parts and reduce costs while maintaining uniform and excellent heat transfer characteristics. Can be.

Embodiment 2 In this embodiment, as shown in FIG. 7, after inserting the inner fin 2 into the flat tube 10 of Embodiment 1, the flat tube 10
This is an example in which the welded portion is pressed from outside using a convex jig 8. Others are the same as the first embodiment. As a result, the weld bead 16 of the flat tube 10 is strongly pushed into the gap 26 of the inner fin 2, and the connection state with the inner fin 2 becomes strong. Therefore, the joining state between the flat tube 10 and the inner fin 2 obtained by the subsequent brazing becomes very strong. The other effects are the same as those of the first embodiment.

Embodiment 3 In this embodiment, a brazing tube 30 is used in place of the flat tube 10 in Embodiment 1 as shown in FIG. That is, the brazing tube 30 is formed by providing bent portions 31 at both ends of a material, brazing them against each other, and forming them into a flat shape. Then, the bent portion 31
Are located inside the tube wall of the flat tube 3, and this is used as a positioning portion 36.

In this case, since the flat tube 3 is a brazing tube having the positioning portion 36, the flat tube 3 may be brazed integrally with the inner fin 2 after roll forming, and a welding process is not required, and the process can be streamlined. it can. The other effects are the same as those of the first embodiment.

Embodiment 4 In this embodiment, as shown in FIG. 10, a flat tube 40 is used in which a welded round tube is formed so that a weld bead 46 on the inner surface comes to an end. As the inner fin 7, as shown in FIGS. 9 and 10, a single rib body 70 having a large number of ribs 71 is folded in half from the center.

First, the flat tube 40 was produced by using a round welded tube similar to that of the first embodiment, and forming the flat roll by roll forming in the same manner as the first embodiment. At this time, the welding bead 46 is
As shown in FIG. 0, it was positioned so as to come to one end of the flat tube 40. The flat tube 40 is provided with a groove 47 for positioning the inner fin 7. The groove 47 was formed by processing a material before molding using a convex roll.

On the other hand, as shown in FIG. 9, the inner fin 7 is a single rib 70 having bent portions 76 at both ends.
Was used. Then, by performing roll forming on the rib body 70 in the same manner as in the first embodiment, the rib body 70 was folded in two such that the bent portions 76 were fitted to each other on the back surface. As a result, as shown in FIG. 10, the inner fin 7 having the engaging portion (bent portion) 76 protruding on both the front and back sides at one end was obtained.

Next, the inner fin 7 is inserted and arranged in the fluid passage 45 of the flat tube 40. At this time, inner fin 7
Is inserted into the flat tube 40 with the engaging portion 76 engaged with the groove 47. Next, the flat tube 40 containing the inner fin 7 is entirely heated. Thereby, the flat tube 4 in which the inner fin 2 is integrally brazed to the optimum position in the flat tube 40 is obtained.

Since the inner fin 7 is simply folded into two from the center, the flat tube 4 can be easily manufactured and the process can be streamlined. In addition, the positioning portion of the flat tube 40 is formed by the groove 47, while the engagement portion 76 of the inner fin 7 is formed by the bent protrusion, whereby the rigidity of the inner fin 7 is increased, and the insertion into the flat tube 40 can be performed. The effect that it becomes easy is obtained. In other respects, the same effects as in the first embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the structure of a flat tube for a heat exchanger according to a first embodiment.

FIG. 2 is a perspective view of a welded round tube in the first embodiment.

FIG. 3 is an explanatory view showing a flat tube forming step in the first embodiment.

FIG. 4 is a perspective view of a rib body according to the first embodiment.

FIG. 5 is an explanatory view showing an inner fin forming step in the first embodiment.

FIG. 6 is an explanatory view showing a state in which the inner fin is inserted into the flat tube according to the first embodiment.

FIG. 7 is an explanatory view showing a pressed deformation state of a flat tube welded portion by a convex jig in a second embodiment.

FIG. 8 is an explanatory view showing the structure of a flat tube for a heat exchanger according to a third embodiment.

FIG. 9 is a perspective view of a rib body according to a fourth embodiment.

FIG. 10 is an explanatory view showing the structure of a flat tube for a heat exchanger according to a fourth embodiment.

FIG. 11 is an explanatory view showing the structure of a conventional flat tube for a heat exchanger.

[Explanation of symbols]

 1,4. . . Flat tubes for heat exchangers, 10, 30, 40. . . Flat tube, 15. . . Fluid passage, 16, 36. . . Welding bead (positioning part), 2,7. . . Inner fin, 20, 70. . . Rib body, 21, 71. . . Rib, 26. . . Gap (engaging portion), 47. . . Groove (positioning portion), 76. . . Engaging part,

Continued on the front page (72) Inventor Ken Yamamoto 1-1-1, Showa-cho, Kariya-shi, Aichi, Japan Denso Co., Ltd. (72) Inventor Masahiro Shimoya 1-1-1, Showa-cho, Kariya-shi, Aichi, Japan Denso, Inc.

Claims (5)

[Claims] 1. A flat tube constituting a fluid passage for a heat exchanger, the flat tube having a flat cross section and having a fluid passage therein, and a flat tube having a fluid passage therein, and inserted into the fluid passage of the flat tube. An inner fin for disturbing the flow of the fluid, wherein the inner fin comprises a single rib having a plurality of ribs arranged obliquely parallel to the longitudinal direction of the flat tube. The rib body is configured to be folded twice so that the ribs cross each other, and the inner fin has an engaging portion provided along the longitudinal direction, while the flat tube is A heat exchanger having a positioning portion engageable with the engaging portion, wherein the inner fin is disposed in the flat tube by engaging the engaging portion with the positioning portion. Flat Tube. 2. The engagement portion of the inner fin according to claim 1, wherein the engagement portion of the inner fin is formed by a gap provided between the opposite ends while bending both ends of the rib body from right and left along the longitudinal direction. On the other hand,
The flat tube for a heat exchanger, wherein the positioning portion of the flat tube is formed by a projection provided on an inner surface of a tube wall of the flat tube along a longitudinal direction thereof. 3. The flat tube according to claim 2, wherein the flat tube is a welded tube, and the positioning portion is formed of a weld bead provided on an inner surface of a tube wall of the welded tube along a longitudinal direction thereof. Flat tube for heat exchanger. 4. A flat tube for a heat exchanger, comprising: a flat tube having a flat cross-sectional shape and having a fluid passage therein; and an inner fin inserted into the fluid passage of the flat tube to disturb the flow of fluid. First, a round pipe having a circular cross section having a projection along the longitudinal direction on the inner surface of the pipe wall is prepared, and the round pipe is pressed and deformed so that the projection approaches the facing pipe wall. In this manner, the flat tube having a flat cross section is manufactured, and a single rib body having a plurality of ribs arranged obliquely in parallel with the longitudinal direction of the flat tube is prepared. An inner fin is formed by bending the left and right sides from each other along the longitudinal direction and providing a gap between the opposite ends. Then, the inner fin is inserted into the flat tube while the gap is engaged with the projection. Insert and follow A method for manufacturing a flat tube for a heat exchanger, wherein the two are integrally joined. 5. The heat pipe according to claim 4, wherein the round pipe is a welded pipe, and the projection is formed of a weld bead provided on an inner surface of a pipe wall of the welded pipe along a longitudinal direction thereof. Manufacturing method of flat tubes for exchangers.