JPH1047881A - Flat tube of stacked type heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable reduction of a soldering fault by a method wherein one or both of the thicknesses in the vicinity of the fold end of a plate and in the vicinity of the opposite edges of the plate are formed to be larger than that of the rest of the plate in a flat tube of a stacked type heat exchanger. SOLUTION: A flat tube 2 used for a stacked type heat exchanger is formed by folding a plate having joining parts 20 provided in the opposite ends and beads 21 provided in the longitudinal direction, at a fold part 22 in the center, and has passages 24 divided by the beads 21 inside. Flat parts 23 are provided respectively with stepped parts 25 along the fold part in the longitudinal direction, and on the opposite sides of the stepped parts as the boundaries, ordinary flat parts 23a which occupy the most part of the flat parts 23 and projecting flat parts 23b which are positioned to the fold part 22 and project outward from the ordinary flat parts 23a are provided. A space between the outer walls of the ordinary flat parts 23a is made a thickness (a) corresponding to a corrugated fin and a header pipe, while a space between the outer walls of the projecting flat parts 23b opposed to each other is made a thickness (b) which is made larger a little than the thickness (a).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat tube of a laminated heat exchanger which is laminated with fins interposed therebetween.

[0002]

2. Description of the Related Art Generally, flat tubes having a flat cross-sectional shape are laminated in parallel with each other with fins interposed therebetween, and the ends of the flat tubes are respectively connected to distribution collecting members such as header pipes. There is known a stacked heat exchanger in which a heat exchange medium is meandered a plurality of times between inlet and outlet joints provided in a distribution collecting member.

[0003] A so-called forming tube in which a flow path inside the tube is divided into a plurality of sections is used as a flat tube of this type of laminated heat exchanger, and the heat exchange rate and the pressure resistance are mainly improved. In other words, the portion that separates the internal flow path increases the contact area for heat exchange with the internal flowing medium to improve the heat exchange rate, and at the same time, acts as a reinforcing member against internal and external pressures to increase the structural strength of the tube. It is designed to increase the pressure resistance. In addition, in particular, since a laminated heat exchanger with a capacitor specification requires an excellent heat exchange rate and pressure resistance, a flat tube also needs an excellent heat exchange rate and pressure resistance. Various forming tubes are frequently used.

[0004] As the forming tube, a bead type using a bead integrally formed with the tube and an inner fin type using an inner fin of another member have been proposed. This bead-type tube is formed integrally with a circular or elongated protrusion (hereinafter, referred to as a bead) that protrudes inward in a flat portion of the tube, and the bead forms a flow path inside the tube. They are separated. Further, as disclosed in, for example, Japanese Utility Model Laid-Open No. 5-52565, an inner fin type tube is formed by inserting a corrugated inner fin having a predetermined cross-sectional shape into a tube tube, and then crushing the tube. The fin is brought into contact with the inner wall of the flow path to divide the internal flow path into a plurality.

The bead type tube has an advantage that the manufacturing cost is lower than that of the inner fin type tube. That is, this is because the bead type tube does not require a separate inner fin, so the number of tube components is small, and the step of inserting such an inner fin into the tube and the flow of the inner fin are not required. This is because a step of crushing the tube or the like to be brought into contact with the inner wall of the road can be omitted.

Furthermore, such a bead-type tube can further increase the heat exchange rate depending on the arrangement and shape of the beads. That is, the beads are configured to cause turbulence in the heat exchange medium flowing through the tube,
By agitating the medium, for example, the heat distribution of the medium itself can be made uniform, or one phase of the medium in a gas-liquid mixed state can be promoted.

These flat tubes are made of, for example, an aluminum material containing an aluminum alloy as a raw material, and are manufactured by bending a long plate having a plate thickness of about 0.4 mm and processing the plate into a semi-tubular shape. It is manufactured by combining the formed tube members. Above all,
A tube manufactured by bending a single plate is easy to mold and has a small number of seams, so that it is excellent in airtightness.

The flat tube formed by bending a single plate is manufactured, for example, as shown in FIG. That is, first, a plate 21 formed in a long plate shape having a predetermined dimension is provided with a bead 21 along a longitudinal direction thereof by roll forming, press forming, or the like. (See FIG. 6 (a)). Then, a predetermined radius of curvature is provided at the bent portion 22 at the center in the width direction shown by the dashed line so as to join the joining portions 20 together. After bending (see FIG. 6B), the flat tube 13 is finally formed in a flat shape whose width direction is longer than its thickness direction (see FIG. 6C).
Thus, the flat tube 13 is formed with the flat portion 23 formed in a plane shape parallel to each other, and the inside of the flat tube 13 is formed with the flow path 24 divided into a plurality by the beads 21.

The longitudinal ends of the flat tube 13 push back the bead 21 to return the outer shape in the vicinity thereof to a shape without irregularities. That is, since both ends of the flat tube 13 are connected to the insertion holes provided in the distribution collecting member such as the header pipe, the joints are prevented from leaking.

FIG. 7 is a sectional perspective view of the flat tube 13. In the flat tube 13, the outer wall spacing (ie, the thickness of the flat tube 13) of the flat portions 23 on both sides facing each other is uniformly equal to a predetermined thickness a (for example, about 1.7 mm) corresponding to the fin and the header pipe. ). In addition, since the joining portions 20 and the top of the bead 21 and the inner wall portion of the flow path 24 facing the joining portion need to be joined by brazing, a brazing material is embedded in a contact state or at the time of brazing. It is assumed that the state is close by.

However, if the plate is simply bent, the gap between the opposed flat portions 23, 23 slightly opens due to the return action (spring back) of the bent portion 22 due to the elastic force of the bent portion 22. In addition, the top of the bead and the inner wall portion of the flow path are almost separated from each other for brazing.

For the excessive interval due to the springback, the flat tubes 13 are laminated with fins interposed therebetween,
When the flat portions 23 on both sides are in pressure contact with the fins, they are almost completely eliminated. At this time, if necessary, the layer of the flat tube may be pressed from both sides using a jig or the like.

Thereafter, the assembled body (Assy) composed of the flat tube 13, the fins and the header pipe 4 is sent into a furnace, subjected to a heat treatment, and brazed integrally.
Prior to this heat treatment, a brazing material is clad and a flux is applied to required portions. Since it is difficult to apply the brazing material clad and flux inside the flat tube 13, a brazing sheet or the like on which the brazing material is clad in advance is generally used as a plate forming the flat tube 13. The inside may be coated with flux before bending.

By this brazing, the flat tube 13
Of the flat tube 13 and the fins, and the connection between the end of the flat tube 13 and the header pipe, and the like. You.

[0015]

However, in the integral brazing of a laminated heat exchanger using a flat tube formed by bending a single plate as described above, the joints between the flat tubes and the beads are not required. The top part and the inner wall part of the passage become partially brazed, and the heat exchange rate decreases.
In addition, there is an inconvenience that causes external leakage and a breakdown voltage defect.

This is because the brazing interval between the joints and between the top of the bead and the inner wall portion of the flow path is extremely small (for example, 0.1 mm or less). If the pressure contact between the fin and the flat part becomes slightly loose due to the degree of assembling and errors in the corresponding dimensions of each part,
This is because the joints and the top of the bead and the inner wall of the flow path are slightly separated from each other, and a sufficient brazing material cannot be obtained therebetween.

In particular, the brazing material that melts from the outer surface of the plate also enters the joints of the flat tubes, while the brazing material that melts from the inner surface of the plate only Since they do not penetrate, when they are separated from each other by springback, the brazing becomes remarkably defective.

[0018] Furthermore, it is also because the pressing force of the fins disposed above and below the flat tube cannot be sufficiently obtained against the springback force on the flat tube side described above. That is, due to the springback force, the gaps formed between the joint portions of the flat tubes and between the top of the bead and the inner wall portion of the passage are narrowed to such an extent that both forces are balanced. If not, the gap is set too wide for brazing.

In particular, at both ends of the tube to be inserted into the insertion hole having a predetermined thickness of the header pipe, the insertion hole restricts the tube thickness to a predetermined value. Not regulated by the insertion hole,
This disadvantageous tendency is remarkable in the middle portion of the tube in the longitudinal direction of only the pressing force by the tube.

Therefore, such a flat tube has a high rate of defective brazing and has a disadvantage that a satisfactory heat exchange rate and pressure resistance cannot be obtained particularly when used in a laminated heat exchanger of a capacitor specification. Was.

Accordingly, the present invention provides a bead-type flat tube formed by bending a single plate,
When the fins are interposed and laminated, the flat portion and the fin are securely pressed against each other, so that the joints and the top of the bead and the inner wall portion of the flow path can be brazed. It is an object of the present invention to provide a flat tube of a laminated heat exchanger which is maintained at a low temperature and has reduced brazing defects.

[0022]

According to the present invention, in order to solve the above-mentioned problems, a single plate made of an aluminum material containing an aluminum alloy is bent so that both edges of the plate are abutted with each other, and the thickness in the width direction is increased. The plate is formed in a flat shape longer than the vertical direction, and the flat flat portion is provided with a protruding portion for dividing an internal flow path. And in the flat tube of the laminated heat exchanger in which the top of the protrusion and the inner wall of the flow path are joined, one of a thickness near the bent end of the plate and a thickness near both edges of the plate. Alternatively, both are formed to be larger than the remaining thickness.

As described above, when the thickness in the vicinity of the bent end of the plate or the thickness in the vicinity of both edges of the plate is formed larger than the remaining thickness, the fin and the flat portion of the flat portion are formed. By pressing against the thick part, the edges of the plate and the abutment of the top of the projection and the inner wall of the flow path are maintained in a brazable state. Further, when both the thickness in the vicinity of the bent end of the plate and the thickness in the vicinity of the both edges of the plate are formed to be larger than the remaining thickness, similarly, the thickness of the fin and the flat portion is formed. By pressing against a portion having a large diameter, the edges of the plate and the abutment of the top of the protrusion and the inner wall portion of the flow path are maintained in a brazable state. This makes it possible to obtain a flat tube of the laminated heat exchanger with reduced brazing defects.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below in detail with reference to FIGS.

In the laminated heat exchanger 1 of this embodiment, as shown in FIG. 1, a plurality of flat tubes 2 are laminated with a corrugated fin 3 for heat radiation interposed therebetween. Are inserted into the insertion holes 7 of the header pipes 4 arranged on both sides, respectively, and are connected to each other.

The upper and lower openings of the header pipe 4 are closed by blind caps 8 and are partitioned by a partition plate 9 provided at a predetermined position in the body, and an inlet joint 10 or an outlet joint 11 is provided. I have. The upper and lower ends of the layer composed of the laminated flat tube 2 and corrugated fin 3 are:
It is supported and protected by a side plate 12 erected on the header pipe 4. Then, the heat exchange medium introduced into the heat exchanger 1 is meandered a plurality of times through the flat tube 2 between the inlet and outlet joints 10 and 11, and when the heat exchange medium passes through the flat tube 2, Heat exchange.

FIG. 2 is a sectional perspective view of a flat tube 2 used in the laminated heat exchanger 1.

The flat tube 2 is formed by bending a single plate provided with a joint portion 20 and a bead 21 in the longitudinal direction at both ends by roll forming at a central bent portion 22 and inside the plate. It is provided with a flow path 24 defined by a bead 21. Further, the thickness in the vicinity of the bent portion 22 is slightly increased, so that when the lamination is performed with the corrugated fins 3 interposed therebetween, The structure is such that the pressure contact between the portion 23 and the corrugated fin 3 is not loosened.

That is, each flat portion 23 is similarly formed by a roll forming step 2 along the bent portion in the longitudinal direction.
5 and the flat portion 23
And a protruding flat portion 23b which is located near the bent portion 22 and protrudes outward from the normal flat portion 23a. As shown in the figure, the interval between the outer walls of the opposing normal flat portions 23a, 23a is
The thickness a (for example, 1.7 mm) corresponding to the corrugated fin 3 and the header pipe 4 is set. On the contrary,
The interval between the outer walls of the opposed protruding flat portions 23b, 23b is a thickness b (for example, a thickness a =
For 1.7mm, both sides are 0.05mm ~
Thickness increased by about 0.1 mm, that is, thickness b = 1.7
+ 2 × (0.05 to 0.1) mm).

Prior to laminating the flat tubes 2, the joints 20 and the top of the bead 21 and the inner wall of the passage 24 tend to be separated from each other by a springback or the like, as in the prior art. In particular, since the springback starts from the bent portion 22 and the gap distance between the joints increases as the distance from the start point increases, the gap distance between the joints 20 is maximized. .

By temporarily assembling the flat tube 2 configured as described above, the gap distance between the joints due to the spring back of the flat tube 2 can be reduced.
Appropriate clearance for brazing can be set at each joint.

That is, such a flat tube 2 is
As shown in a partially broken perspective view of FIG. 3, the corrugated fins 3 are interposed on the upper and lower surfaces, and the pressing force from the corrugated fin 3 is applied to the projecting flat portion 23 b of the flat tube 2. Added.

The corrugated fin 3 is made of a thin metal material having excellent heat conductivity and is formed in a wavy shape meandering up and down, and its upper and lower end surfaces are aligned with a parallel surface at a predetermined distance. That is, the distance and the height of the upper and lower end surfaces of the corrugated fins 3 are set to the height reaching the normal flat portion 23a which is the non-projecting portion of the tubes to be laminated, as in the conventional case.

Accordingly, the corrugated fins 3 are set in the height dimension as described above, and the protruding flat portions 23b of the flat tubes 2 protrude toward the corrugated fins 3 side. Since the pressing force is supplied from 3, it is deformed by pressing,
That is, the upper and lower thicknesses of the flat tube 2 are compressed.

The ends of the flat tubes 2 are respectively inserted into insertion holes 7 of the header pipe 4. The corrugated fin 3 has its crest abutted on the flat portion 23 and is mounted on the flat tube 2. Generally, the step 25 formed in the flat portion 23 is absorbed by the partial deformation of the corrugated fin 3, and the crest of the corrugated fin 3 straddles the normal flat portion 23 a and the protruding flat portion 23 b having different phases. Contact.

When the flat portion 23 and the corrugated fin 3 are pressed against each other, the springback of the flat tube 2 is suppressed, and the joint portions 20 and the top of the bead 21 and the inner wall portion of the flow path 24 can be brazed. It is in a state of contact or proximity. The press contact between the flat portion 23 and the corrugated fin 3 is performed by the normal flat portion 23a at the projecting flat portion 23b.
Since it is more powerful as it protrudes, it is suitable for suppressing springback based on the bent portion 22.

If the assembly is not perfect,
Alternatively, even if there is an error in the corresponding dimension of each part, the pressure contact between the flat part 23 and the corrugated fin 3 becomes loose because the thickness of the flat tube 2 is slightly increased near the bent part 22. No joints 20 and beads 2
1 and the inner wall portion of the flow path 24 are maintained in a brazable manner.

After the flux is applied, the assembled body is sent into a furnace where it is subjected to a heat treatment and brazed integrally. The joints 20 and the top of the bead and the flat portion 23
Means that sufficient brazing material is obtained between them and they are joined by this brazing.

According to the first embodiment described above, the thickness of the flat tube in the vicinity of the bent portion is slightly increased, so that the flat portion and the corrugated fin when the flat tubes are laminated with the corrugated fin interposed therebetween. Is suitable for suppressing springback, and the joints between the joints and between the top of the bead and the inner wall portion of the flow path can be brought into a brazable state. Even if the condition is not perfect or there is an error in the corresponding dimensions of each part, the flat part and the corrugated fin 3
The contact between the joint portion and the top of the bead and the inner wall portion of the flow path can be maintained in a brazable state. Therefore, it is possible to reliably braze the joints and the top of the bead and the inner wall portion of the flow path, and reduce brazing failure.

As described above, according to the first embodiment of the present invention, the tube thickness of the flat tube near the bent portion of the tube is increased, so that the flat portion having the increased thickness is provided with a corrugated fin. Since the applied pressing force increases more than before and the tube is compressed in the thickness direction, the gap between the joints of the tube caused by springback or the like is reduced, and an appropriate clearance for brazing is obtained. That is, good brazing properties can be ensured for the tube itself.

Next, a second embodiment of the present invention will be described in detail with reference to FIG.

As shown in FIG. 4, the flat tube 2 of this embodiment is different from the above embodiment in that a flattened portion 23b projecting from the normal flat portion 23a is provided near the end on the joint portion 20 side.
The thickness of the tube in the vicinity of the joint 20 is slightly increased.

That is, the position of the protruding flat portion 23b in the tube width direction is the position of the bead 25 positioned on the joint portion 20 side.
And the joint portion 20, and protrude from the upper and lower surfaces of the flat tube 2 by a predetermined amount in the vertical direction in the same manner as in the specific example.

The flat tube 2 is assembled integrally with the corrugated fin 3 and the header pipe 4 in the same manner as in the above embodiment, and the joints 20 and the top of the bead 21 and the inner wall of the flow path 24 are brazed. Joined.

Therefore, according to the flat tube of the present embodiment, the pressure contact between the corrugated fin and the flat portion is not loosened similarly to the above-described embodiment by increasing the thickness of the flat tube in the vicinity of the tube joint. The joints, the top of the bead, and the inner wall portion of the flow path can be maintained in a brazable manner.

In addition, when formed in this way, particularly, it is possible to reliably bring the joints into contact with each other.
External leakage of the tube due to poor brazing of the joints can be prevented, and the yield can be improved.

Further, the height dimension between the joint and each bead is
When the joint portions are abutted with each other when the size is slightly reduced in order from the bent portion side, all the beads can be sequentially contacted from the bent portion side, which is more effective.

In the figure, one step 25 'is formed by roll forming together with the inclined portion of the bead 21', and it is not necessary to add a roll forming step for forming the step 25 '. The number can be reduced.

Next, a third embodiment of the present invention will be described in detail with reference to FIG.

As shown in FIG. 5, the flat tube 2 of this embodiment incorporates both of the first and second embodiments, and has a flattened portion 23b projecting from the normal flat portion 23a.
Is provided near the bent portion 22 and the joining portion 20 side end, and the thickness of the tube in the vicinity of the bent portion 22 and the joining portion 20 is slightly increased.

Therefore, according to the flat tube of this embodiment, the thickness of the flat tube near the bent portion and the joint portion is increased, so that the pressure contact between the corrugated fin and the flat portion is increased in the same manner as in the specific example. Without loosening, the joints, the top of the bead, and the inner wall portion of the flow path can be maintained in a brazable manner.

Further, in the case of such a formation, it is possible to make sure that the joining portions come into contact with each other.
External leakage of the tube due to poor brazing of the joints can be prevented, and the yield can be improved.

In particular, according to the flat tube of this example,
The overall bias due to the difference in thickness can be eliminated.

[0054]

According to the flat tube of the laminated heat exchanger of the present invention described above, the flat tube of the laminated heat exchanger formed by bending one plate and interposing fins is provided. One or both of the thickness in the vicinity of the bent end of the plate and the thickness in the vicinity of both edges of the plate are formed to be larger than the remaining thickness. The parts are pressed into contact with each other, and abutment between the joints, the top of the bead, and the inner wall portion of the flow path can be made to be in a brazable state.

Even if the assembling condition is not perfect or there is an error in the corresponding dimension of each part, the pressure contact between the flat part and the fin does not loosen, and the joint part and the top of the bead are not loosened. Can be maintained in a brazable state. Therefore, the joining portions and the top of the bead and the inner wall portion of the flow path can be reliably brazed, and as a result, brazing defects can be reduced.

[Brief description of the drawings]

FIG. 1 is a front view showing an entire schematic according to a specific example of the present invention.

FIG. 2 is a partially broken perspective view showing the flat tube of the present example.

FIG. 3 is a partially broken perspective view showing a state in which the flat tube of the present example is temporarily assembled.

FIG. 4 is a partially broken perspective view showing a flat tube according to another embodiment of the present invention.

FIG. 5 is a partially broken perspective view showing a flat tube according to another embodiment of the present invention.

FIG. 6 is a perspective view of a conventional flat tube.

FIG. 7 is a perspective view of a conventional flat tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stacked heat exchanger 2 Flat tube 3 Corrugated fin 4 Header pipe 7 Tube insertion hole 8 Blind cap 9 Partition plate 10 Inlet joint 11 Outlet joint 12 Side plate 13 Flat tube 20 Joint 21 Bead 21 'Bead 23 Flat 23a Normal Flat portion 23b Protruding flat portion 24 Flow path 25 Step 25 'Step

Claims (1)

[Claims] 1. A plate made of an aluminum material containing an aluminum alloy is bent so that both edges of the plate abut each other, and the width direction is formed in a flat shape longer than the thickness direction. The flat portion is provided with a protrusion that separates the internal flow path, and the both ends of the plate and the top of the protrusion and the inner wall portion of the flow path are alternately laminated with fins and brazed by brazing. In the flat tube of the laminated heat exchanger to be joined, one or both of the thickness in the vicinity of the bent end of the plate and the thickness in the vicinity of both edges of the plate,
A flat tube of a laminated heat exchanger, wherein the flat tube is formed to have a thickness larger than the remaining thickness.