JPH0545337B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a heat transfer tube for a finned heat exchanger, in which a refrigerant flows, in an air conditioner or the like.

BACKGROUND ART In recent years, the performance of heat exchangers with fins has been increasing, and the inner shape of heat exchanger tubes has also been studied.

An example of the above-mentioned conventional finned heat exchanger will be described below with reference to the drawings.

FIG. 10 is a sectional view of a finned heat exchanger in a conventional air conditioner.

In FIG. 10, fins 1 are arranged in parallel at predetermined intervals, and 2 is a heat exchanger tube having a hair-pinch tube portion 3 formed by molding a copper tube into a U shape, and inserted into the fin 1 at right angles.

11 to 15 show one manufacturing process of a conventional grooved heat exchanger tube, and 10 is a metal flat plate;
8 is a groove group part, 9 is a non-groove group part, and 14 is a grooved heat exchanger tube obtained by pipe-making the metal flat plate shown in FIG.

Such a configuration is shown in, for example, Japanese Patent Laid-Open No. 113562/1983.

The operation of the heat exchanger with fins configured as described above when the heat transfer tubes function as a condenser will be described.

The refrigerant enters the heat transfer tube 2 in a gas state from the inlet (not shown), and while flowing out from the outlet (not shown), condensation is promoted by the groove group 8 of the heat transfer tube 2, and the gas is liquefied. be done.

Problems to be Solved by the Invention However, when a heat exchanger tube and a heat exchanger are constructed with such a structure, the positions of the groove group portion 8 and the non-groove group portion 9 are uncertain, so the location of the groove group portion 8 is Although the heat transfer coefficient improves, if the position corresponds to, for example, the hair pinch tube 3 in the heat exchanger, which does not directly contribute to heat exchange, the wall thickness of the hair pinch tube 3 is thin. Since the stress applied to the fins is not supported by the fins like other fins, cracks may be caused by the stress.

In this way, by providing the groove group portion 8 and the non-groove group portion 9 mutually in the longitudinal direction of the tube, it has been possible to improve the electrothermal characteristics of the tube inner wall surface. On the other hand, since the positions of the groove group portion 8 and the non-groove group portion 9 are uncertain, the pressure loss within the hair tube portion 3 increases, and cracks may occur due to the thin wall thickness at the root portion 5 of the hair tube portion 3. A problem arises.

Therefore, the present invention aims to eliminate the drawbacks seen in the conventional heat exchanger tubes, and aims to prevent the generation of cracks due to stress at the hair-pin tube portion and to reduce the flow resistance within the tube.

Means for Solving the Problems The technical means of the present invention for solving the above-mentioned problems is to provide a plurality of grooves or irregularities only on the inner surface of the tube group within a range not exceeding both ends of the flat plate fin group, The wall thickness of the portion of the tube where other grooves or unevenness are not formed is made larger than the wall thickness of the groove or the valley of the uneven portion.

Effect The effect of this technical means is as follows.

In other words, when the refrigerant passes through a plurality of grooves or portions that do not have unevenness, it is possible to reduce the flow resistance there, and at the same time, the wall thickness of the pipe in those portions can be reduced by reducing the thickness of the pipe in those portions. Since it is larger than the wall thickness, it has enough strength to withstand stress even if it is not supported by fins.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the accompanying drawings.

As shown in FIG. 1, on one metal flat plate 10,
A groove group portion 8 in which a plurality of grooves or irregularities are formed and a non-groove portion 9 whose wall thickness is larger than the thickness of the valley of the groove group portion 8 are formed, and the length l8 of the groove group portion is extended beyond both ends of the flat fin group. The length l9 of the non-groove portion is processed to be equal to the length of the paired pinch tube portion.

Next, as shown in FIG.
The refrigerant pipe 14 is formed by continuously welding 13 the joint portion 12 as shown in FIG. 3.

Then, bend the hairpin pipe as shown in FIG. 4 so that the non-groove group becomes the hairpinch tube part 15, and then as shown in FIG. Drill a hole, overlap it, and insert a tube (hairpin pipe) into the hole of fin 16.
Then, in order to bring the fins and the tube into close contact, a tube expanding tool 17 having a diameter slightly larger than the inner diameter of the tube is pushed into the tube as shown in FIG. 6, and the tube is expanded from the inside.

Further, a torch brazing method as shown in FIG. 7 is used to join the bend portions 18, and a heat exchanger with fins is manufactured as shown in FIG. 8.

In the above configuration, the hair-pinch tube portion 15, which is the non-groove portion 9, is not subjected to the flow resistance of the refrigerant due to the grooves in the conventional example, so the flow resistance in the pipe is reduced, and the pressure drop of the refrigerant between the inlet and the outlet is accordingly reduced. Since a high evaporation temperature is maintained, the efficiency of the refrigeration cycle side is also improved.

Further, since the thickness of the tube in the non-grooved portion is made larger than the thickness of the valley in the groove group portion, even the hairpinch tube portion that is not supported by the fins has sufficient strength to withstand stress.

Effects of the Invention As is clear from the above examples, the method for manufacturing a heat exchanger with fins of the present invention has a plurality of grooves or irregularities formed only on the inner surface of the tube group portion within a range not exceeding both ends of the flat plate fin group. By making the wall thickness of the part of the pipe where other grooves or unevenness are not formed larger than the wall thickness of the valley of the groove or uneven part, for example, when refrigerant flows inside the pipe, it is possible to The flow resistance of the refrigerant due to the grooves is eliminated, so the flow resistance inside the tube can be reduced.
Furthermore, it is possible to prevent stress cracks caused by the thin wall thickness of the conventional hair pinch tube due to the grooves and the fact that this part is not supported by fins or the like.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing a flat plate with groove group portions and non-grooved portions formed, Fig. 2 is a perspective view showing a state in which the flat plate in Fig. 1 is wound, and Fig. 3 shows the same winding state. Vertical side view, Figures 4a and 4b are the hairpin pipe bending diagram and cutaway diagram of the hairpin pipe, Figure 5 is the setting diagram of the pipe and fins, Figure 6 is the refrigerant pipe expansion process diagram, Figure 7 8 and 9 are perspective views of different heat exchangers with fins, FIG. 10 is a cross-sectional view of the same heat exchanger, and FIG. FIG. 12 is a plan view showing a state in which grooves are formed, and FIG.
Fig. 3 is a side view of the metal plate shown in Fig. 12, Fig. 14 is a perspective view of a grooved heat exchanger tube obtained by pipe-making the metal plate shown in Fig. 12, and Fig. 15 is a cross section taken along the - line in Fig. 14. It is a diagram. 8... Groove group portion, 9... Non-groove portion, 14... Heat exchanger tube, 15... Hair pinch tube portion, 16... Flat plate fin, 17... Tube expansion tool, 18... Bend.

Claims (1)

[Claims] 1 A heat exchanger with fins is composed of a group of flat plate fins arranged in parallel at a predetermined interval, through which air flows, and a group of tubes inserted at right angles to the flat plate fins, through which fluid flows, A flat metal plate is formed with multiple grooves or a groove group portion with unevenness and a non-groove portion whose wall thickness is larger than the thickness of the valley of the groove group portion, and the length of the groove group is set to the length between both ends of the flat plate fin group. The length of the non-groove part is processed to be equal to the length of the hair pinch tube part,
A method for manufacturing a heat exchanger tube for a finned heat exchanger, in which the ends of a metal flat plate are wound to form a tube so that the grooves are located on the inside, and the joints are continuously welded.