JPS6159194A - Heat exchanger - Google Patents

Abstract

PURPOSE:To prevent the stress corrosion cracking, by forming a groove in the outer surface of a bent section of a flatten tube in such a way that the resulting groove formed section may project into the tube, and applying solder plating to the groove. CONSTITUTION:Each core metal is placed in each tube 1 and the tube 1 is passed between a pair of rollers each having two ridges on the circumferential surface so that the tube is formed with a groove, and solder plating is applied to the tube using the capillarity to fill the groove 10 with the plating. Thereafter, the tubes 1 and corrugated fins 2 are secured by brazing to form a heater core 3. Thus, as the bent section of each flattened tube 1 is formed with the groove 10, the hardness of the bent section has been increased by machining the tube to form the groove 10, and the solder layer 11 filling the groove 10 acts as a beam, if a pressure (P) is applied to the inside of the tube, the pressure resistant strength of the bent section of the tube 1 against the inner tensile strength can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat exchanger comprising a flat tube and heat transfer fins joined to the flat tube in a heat conductive manner. It is suitable for the heater core of a hot water type heating system for automobiles.

(Prior Art) Conventionally, for example, a flat tube 20 of a heater core of a hot water heating system has a thin brass plate attached to one end 2 as shown in FIG.
A seam is formed at 0a.

Incidentally, in recent years, the thickness of the flat tube 20 has also tended to become thinner in the heat exchanger for automobiles as described above as the heat exchanger is made smaller and lighter. On the other hand, in order to improve the heat exchange performance of the heat exchanger, it is necessary to increase the pressure of the heat exchange fluid flowing through the flat tubes.

However, in the conventional flat tube 20, when the internal pressure of the flat tube 20 increases, large tensile stress concentrates on the circular arc portion 20b at the end of the tube due to the expansion of the flat tube portion 20C, and stress corrosion cracking occurs in the circular arc portion 20b. may occur.

(Problems to be Solved by the Invention) Therefore, the present invention has been made in order to improve the pressure resistance against tensile stress at the bent portion of the flat tube, which causes stress localization in the flat tube.

(Means for solving the problem) Therefore, in the present invention, in order to solve the above problem, a groove is provided on the outer surface of the bent portion of the flat tube that protrudes into the inside of the tube, and solder plating is applied to fill this groove. .

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

Fig. 1 shows a corrugated fin type heat exchanger according to the present invention, and this heat exchanger serves as the heater core 3 of an automobile hot water heater, and heats the air as it passes in the direction of arrow A. ing. In the illustrated embodiment, the core portion includes a plurality of tubes l arranged in a row in the width direction in the air flow direction A at intervals in the transverse direction with respect to the air flow direction A, and the side surfaces of these tubes. It consists of corrugated fins 2 connected to each tube and tube row. Each tube 1 is a flat tube formed so that cooling water for an automobile engine flows therethrough, and is usually made of brass. Corrugated fin 2 is made of copper. In addition to copper, the tube 1 and the fins 2 may be made of aluminum, which has good heat conductivity.

Both ends of each tube 1 are respectively connected to a header plate 6.7 of the Huangdong Alliance to complete the core 3. A tank 4.5 is attached to each header plate 6.7 in a known manner. The upper tank 4 is provided with a cooling water artificial vibrator 8 and a cooling water outlet pipe 9.

FIGS. 2 and 3 show enlarged views of the tube 1 in this embodiment, and FIG. 1 shows the tube 1 formed by folding the tube 1 at one end 1a (a folded tube). , FIG. 3 shows a tube (welded tube) in which an electric resistance welded tube is welded in the middle of the flat part 10. As can be clearly seen from FIG. 2, in the folded tube 1, the outer surface of the bent portion, which is the other end opposite to the folded portion 1a, has a depth of 0.3 to 0.4 m.
m grooves 10 are provided, and in the welded tube 1 shown in FIG. 3, grooves 10 are provided on both bends.

These grooves are formed by forming a tube 1 with a cross-sectional shape as shown in FIGS. 2 and 3 from a thin brass plate, and after appropriately welding or brazing a butt green (not shown), for example, The tube 1 can be formed by inserting a core metal into the tube 1 and passing the tube 1 between a pair of a-ra each having two ridges parallel to the circumferential surface. Of course, the grooves can also be formed using other methods.

After forming the groove, solder plating is applied to the tube l by capillary action, and the solder coating layer 11 is applied as shown in FIG.
Fill the groove with 10 force (so that it is filled in).

Thereafter, the tube 1 and the corrugated fins 2 are fixed by brazing, and a heater core 3 as shown in FIG. 1 is obtained. At this time, the solder layer 11 adsorbed to 'tR10 during brazing is held in the groove 10 by pseudo-contraction force.

As described above, in this example, since the groove 10 is formed in the bent portion of the flat tube 1, when the pressure P is applied inside the tube, as shown in FIG.
Hardness is improved by work hardening during formation of 1ffilO, and since the solder layer 11 provided in the groove 10 has the effect of a kind of beam, the pressure resistance against internal tensile stress at the bent portion of the tube 1 is improved. the result,
Stress corrosion cracking at the bend in flat tube 1 is I
JIt is actually preventable.

Furthermore, since the li'llll property of the entire flat tube is improved, the fatigue yf strength is improved.

In addition, although the above-mentioned embodiment applies the present invention to a heater core of a hot water type heater, the present invention is not limited to this. The same can be said.

(V of the invention) As described above, according to the present invention, the compressive strength against tensile stress is improved in the bent portion of the flat tube that constitutes a part of the heat exchanger6. Corrosion cracking is prevented, resulting in improved durability and reliability of the heat exchanger.

Additionally, as the pressure resistance of the flat tube improves, it becomes possible to increase the pressure of the heat exchange fluid flowing inside the flat tube, which increases the flow rate of the heat exchange fluid flowing inside the flat tube, improving heat exchange performance. There is an effect.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a heater core that is a heat exchanger of the present invention, FIGS. 2 and 3 are partial perspective views of a flat tube of the present invention, and FIG. 4 is a sectional view of a main part of a flat tube of the present invention. , FIG. 5 is a partial perspective view of a conventional flat tube. 1... Flat tube, 2... Corrugated fin, 1
0...Groove, 11...Solder plating.

Claims (1)

[Scope of Claims] A heat exchanger including a flat tube through which a heat exchange fluid flows, and heat transfer fins joined to the flat tube in a heat conductive manner, wherein a curved portion of the flat tube is attached to an outer surface of a bent portion of the flat tube. A heat exchanger characterized by having a groove projecting inward and solder-plated to fill the groove.