JP2935071B2 - Flat tubes for heat exchangers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat tube for a heat exchanger used for a heat exchanger such as a condenser or an evaporator for a car cooler, a condenser or an evaporator for a room cooler, a car heater, and a radiator for an automobile.

[0002] In this specification, the term "aluminum" shall include aluminum alloys in addition to pure aluminum.

[0003]

2. Description of the Related Art As a heat exchanger of this kind, for example, a plurality of flat tubes are arranged between a pair of parallel tubular headers and both ends of the flat tubes are connected to the header. It is known that a corrugated fin is arranged and brazed to a flat tube.

Conventionally, the following two types of flat tubes have been used.

(A) An electric resistance welded tube comprising a pair of flat portions facing each other and an arc-shaped portion connecting both side edges of both flat portions, and each flat portion is subjected to press working. A plurality of protrusions projecting inward are formed, and the tips of the protrusions on both flat portions are brazed to each other (Japanese Patent Application Laid-Open No. 59-1984).
-125395).

(B) The whole is formed by an extruded tube, and a pair of flat portions facing each other, an arc-shaped portion connecting both side edges of both flat portions, and a plurality of partition walls dividing the inside in the width direction. What consists of

[0007]

SUMMARY OF THE INVENTION
In the flat tube of (a), the projections form dents on the outer surface of the flat portion of the flat tube, so when used in the heat exchanger, the heat transfer area between the flat tube and the corrugated fin is reduced, There is a problem that heat exchange efficiency is poor.

In the flat tube (b), there is a problem that the extrusion speed must be reduced in order to make the peripheral wall thinner for the purpose of weight reduction, and the productivity is deteriorated. Moreover, since the strength is low, the header may be deformed when inserted into a through hole formed in the peripheral wall of the header.

An object of the present invention is to provide a flat tube for a heat exchanger which solves the above problems.

[0010]

A flat tube for a heat exchanger according to the present invention comprises a pair of flat portions facing each other and an arc-shaped portion connecting both side edges of the flat portions to each other. It is formed of a tube and has two different
A plurality of two types of grooves extending in the direction are formed, and a large number of projections are provided, and the tips of the projections of both flat portions are brazed.

[0011]

Since the entire structure is formed by an electric resistance welded tube, a thin peripheral wall can be easily formed. Moreover, the strength is greater than that formed by the extruded tube.

[0012] Further, the inner surface of each flat portion is provided with two different surfaces.
Since a plurality of two types of grooves extending in the direction are formed and a large number of projections are provided, no dent can be formed on the outer surface.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a heat exchanger using a flat tube for a heat exchanger according to the present invention. In FIG. 1, the heat exchanger (1)
Is a pair of aluminum tubular headers parallel to each other
A plurality of flat tubes (3) are arranged between (2), and both ends of the flat tubes (3) are inserted into long holes (2a) formed in the header (2) and brazed to the header (2). A corrugated fin with an aluminum louver (4) is arranged between adjacent flat tubes (3) and brazed to the flat tubes (3).

The flat tube (3) is, as shown in FIGS.
It is formed by an electric resistance welded tube comprising a pair of flat portions (3a) facing each other and an arc-shaped portion (3b) connecting both side edges of both flat portions (3a). It is welded at the arc-shaped portion (3b). A flat tube is placed on the inner surface of each flat part (3a).
A large number of protrusions (6) are provided by forming a plurality of two types of grooves (5) which form a predetermined angle with the longitudinal direction of (3) and extend in two directions different from each other. The tips of the projections (6) of both flat portions (3a) are brazed. The fluid flows in the flat tube (3) as shown by the arrow in FIG. Therefore, turbulence occurs in the flat tube (3), and the heat exchange efficiency is improved.

Hereinafter, a flat tube (3) will be described with reference to FIGS.
A method for manufacturing an electric resistance welded tube for forming the above will be described. In the following description, the left side of FIG. 5, that is, the direction indicated by the arrow in FIG. In addition, left and right mean backward.

First, a coil (2) made of an aluminum brazing sheet (10) clad on both sides with a brazing material (11).
0) is prepared (see FIG. 6). And this coil (2
While rewinding the aluminum brazing sheet (10) from (0), the predetermined rising edge portion forming portion (12) of the left and right side edges on the upper surface thereof and the bending portion forming portion (13) of the predetermined width at the center portion are formed. The left and right two first rolls (21) and (22) and the second rolls (23) and (24) arranged from the coil (20) side extend and intersect in two different directions. A plurality of two types of grooves (5) are formed. Spiral ridge (21a) formed on the peripheral surface of the first roll (21) on the left side, spiral ridge (23a) formed on the peripheral surface of the second roll (23), and the right side The first roll (2
Spiral ridges (22a) formed on the peripheral surface of 2) and spiral ridges (24a) formed on the peripheral surface of the second rolling roll (24).
a) each has a different twist direction. Also, the spiral ridges (21) of the left first roll (21) are formed.
a) and the spiral ridge (22) of the right rolling roll (22)
a), and the spiral ridge (23a) of the left second roll (23) and the spiral ridge (24a) of the right second roll (24) also have different twist directions. . Then, the first roll (21) (22) and the second roll (2
3) A large number of protrusions (6) are formed on the upper surface of the brazing sheet (10) by the two types of grooves (5) formed by (24) (see FIGS. 7 to 9).

Next, the rising edge forming portions (12) at the left and right side edges of the brazing sheet (10) having a large number of projections (6) formed on the upper surface are connected to the second rolling rolls (23) and (24). Is bent upward by a processing device (25) arranged in front of the rim to form an arc-shaped rising edge (14) (see FIG. 10).

Thereafter, the brazing sheet (10) is raised upward in a V-shape at the bent portion forming portions (13) at the left and right central portions thereof by a bending device (26) disposed in front of the processing device (25). It is bent (see FIG. 11), and the tips of the arc-shaped rising edges (14) are brought into contact with each other. At this time, the bent portion is also formed in an arc shape.

Further, the leading ends of the arc-shaped rising edges (14) are welded by a high-frequency welding device (27) disposed in front of the bending device (26). Thus, an electric resistance welded tube (A) is formed (see FIG. 12).

Next, the outer welding bead is cut by a cutting device (28) disposed in front of the high frequency welding device (27) (see FIG. 13), and finished by a sizing device (29) disposed in front of the cutting bead. After processing, the tips of the protrusions (6) are brought into contact with each other. Finally, it is cut to a predetermined length by a cutting device (30).

In order to form the flat tube (3) with the electric resistance welded tube (A), in manufacturing the heat exchanger (1) shown in FIG.
Insert both ends of the ERW pipe (A) into the slots (2a) of the header (2), and place louvered corrugated fins (4) between adjacent ERW pipes (A), for example, to prevent corrosion. These are collectively brazed in an atmosphere in which steam of a volatile flux is present. At this time, the tips of the projections (6) of the ERW pipe (A) are brazed together.

In this embodiment, since the electric resistance welded pipe (A) is made of an aluminum brazing sheet (10) clad with brazing material (11) on both sides, the corrugated fins (4) of the heat exchanger (1) are formed. It is not necessary to use the brazing sheet (10), and the following effects can be obtained. That is, since there is no brazing material harder than the core material, the life of the fin forming roll having the louver cutting blades forming the louvered corrugated fins (4) is extended. Further, it is possible to prevent burrs from being generated in the louver due to the presence of the brazing material. However, it is not always necessary to clad a brazing material on the outer surface of the ERW pipe (A).

In the above, a flat electric resistance welded tube for forming a flat tube may be manufactured as follows. That is, while rewinding the aluminum brazing sheet (10), the left and right two second sides arranged from the coil (20) side on the upper surface except for a predetermined width portion on the left and right side edges and a predetermined width portion on the center portion. A plurality of two types of grooves (5) extending in two different directions and intersecting with each other are formed by a first roll (21) (22) and a second roll (23) (24). Then, an electric resistance welded pipe having a circular cross section is formed, and then the flattened electric resistance welded pipe is manufactured by deforming the pipe.

[0025]

According to the flat tube for a heat exchanger of the present invention,
As described above, since the whole is formed by the electric resistance welded tube, a thin peripheral wall can be easily formed.
In addition, since the strength is greater than that formed by the extruded tube, it is possible to prevent deformation when the header is inserted into the through hole formed in the peripheral wall of the header.

Also, two different surfaces are provided on the inner surface of each flat portion.
Since a plurality of two types of grooves extending in the direction are formed and a large number of projections are provided, no dent can be formed on the outer surface.
Therefore, when used for a heat exchanger, the heat transfer area between the flat tube and the corrugated fin is increased, and the heat transfer efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a heat exchanger using a flat tube according to the present invention.

FIG. 2 is an enlarged cross-sectional view of the flat tube according to the present invention.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a partially enlarged view of FIG. 3;

FIG. 5 is a diagram illustrating a method of manufacturing an electric resistance welded tube for forming a flat tube.

FIG. 6 is a partially enlarged cross-sectional view of an aluminum brazing sheet used for manufacturing an electric resistance welded tube.

FIG. 7 is a perspective view showing a portion of a roll forming a groove in the aluminum brazing sheet.

8 is an enlarged sectional view taken along line VIII-VIII of FIG.

FIG. 9 is a partially enlarged view of FIG. 8;

FIG. 10 is an enlarged sectional view taken along line XX of FIG. 5;

FIG. 11 is an enlarged sectional view taken along line XI-XI of FIG. 5;

FIG. 12 is an enlarged sectional view taken along line XII-XII of FIG. 5;

FIG. 13 is an enlarged sectional view taken along line XIII-XIII in FIG. 5;

[Explanation of symbols]

 3 Flat tube for heat exchanger 3a Flat part 3b Arc-shaped part 5 Groove 6 Projection A ERW pipe

Claims (1)

(57) [Claims] 1. A flat-shaped electric resistance welded tube comprising a pair of flat portions facing each other and an arc-shaped portion connecting both side edges of both flat portions, and the inner surface of each flat portion has a different shape. A flat tube for a heat exchanger in which a plurality of two types of grooves extending in two directions are formed, a large number of projections are provided, and tips of the projections of both flat portions are brazed to each other.