JPS633712B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a heat exchanger that uses heat transfer tubes equipped with fins to prevent an increase in pressure loss on the fluid side outside the tubes and to increase the heat transfer area.

In a heat exchanger that exchanges heat between two fluids inside and outside the tube, if the heat transfer coefficients of the inside and outside fluids are significantly different,
For example, in the case of air to water as in a radiator, or air to refrigerant that condenses or evaporates as in a condenser or evaporator, fins of various shapes are added to the fluid side with a low heat transfer coefficient, that is, the air side. Some use heat transfer tubes to increase the heat transfer area to bring the amount of heat transfer closer to that which can be transferred by the fluid side with a higher heat transfer coefficient, thereby improving performance. However, if an attempt is made to increase the heat transfer area by using a finned heat transfer tube, there is a contradictory problem in that the pressure loss on the air side, which is the fluid outside the tube, increases and the overall performance of the heat exchanger deteriorates.

For example, in the corrugated fin heat exchanger for automobile air conditioning shown in Figs. A corrugated fin 02 formed into a corrugated shape is arranged and joined to the flat tube 01 by brazing or the like. However, in a corrugated fin type heat exchanger, there is a limit to the narrowing of the pitch P due to limitations in the corrugated fin processing. In the case of 20 mm, the pitch P is limited to about 3 mm. For this reason, there is a limit to the increase in heat transfer area, which is an obstacle to reducing weight and increasing efficiency required for mounting on vehicles. Additionally, louvers 03 are formed by making incisions on the surface of the corrugated fins 02 to disrupt the flow on the fin surface and improve the heat transfer coefficient, but such fin shapes are accompanied by an increase in pressure loss. This has a major drawback in terms of the performance of the heat exchanger, and it is difficult to reduce the weight and improve the efficiency of the heat exchanger due to restrictions on the manufacturing of the heat exchanger and the shape of the fins.

The present invention solves the manufacturing constraints of conventional corrugated fin type heat exchangers and provides a method for manufacturing a heat exchanger that can increase the heat transfer area while preventing an increase in pressure loss. purpose.

The structure of the present invention that achieves this object includes punching out a plurality of fitting holes through which the heat transfer tubes are fitted in accordance with the arrangement of the heat transfer tubes through which fluid flows through a thin metal plate having brazing filler metal clad on both sides. Needle-like fins having a rectangular cross section and a predetermined length and a width substantially equal to the thickness of the thin metal plate are formed at predetermined intervals between these fitting holes, extending along a direction perpendicular to the flow of the extratubular fluid, and forming a needle-like fin plate. After the needle-like fin plates are fitted to the heat transfer tubes and laminated, headers or vent pipes are connected to both ends of these heat transfer tubes to form a fluid flow path within the tubes, and further in a brazing furnace. By heating, the brazing material is melted and solidified, and the heat exchanger tube and the needle-shaped fin plate and the heat exchanger tube and the header or vent pipe are joined by brazing. At the same time, the brazing material on both sides of the needle-shaped fin is melted and solidified, and the surface thereof is melted and solidified. It is characterized in that needle-like fins with a circular cross section are formed by tension.

The method for manufacturing the heat exchanger of the present invention will be described below in Figures 4 to 4.
This will be explained in detail with reference to FIG.

An example of the heat exchanger manufactured by the present invention is shown in FIG. 4 showing its front view and FIG. 5 showing its cross section taken along the line V-V. A needle-like fin plate 3 having a large number of needle-like fins 2 having a circular cross section formed on the outer periphery of the heat exchanger tube 1 is arranged in parallel above the heat exchanger tube 1 and is laminated in the axial direction of the heat exchanger tube 1. A header 4 is connected to the header 4. Therefore, since highly efficient needle-like fins 2 are used as the fins, and these are formed on flat plates and laminated, there are no restrictions on pitch when molding into corrugated fins or the like. Furthermore, since the needle-like fins 2 have a circular cross section, an increase in pressure loss of the extraluminal fluid, such as air, can be suppressed.

Next, a specific manufacturing method will be explained.

First, the needle-like fin plate 3 on which the needle-like fins 2 are formed is formed.The needle-like fin plate 3 is made of a material with high thermal conductivity such as aluminum or copper that has a width wider than the long axis of the flat heat transfer tube 1. A thin metal plate 5 with brazing filler metal 6 clad on both sides is used.

In the illustrated example, five fitting holes 7 through which the heat exchanger tubes 1 can pass are punched in the thin metal plate 5 in accordance with the arrangement of the heat exchanger tubes 1 shown in FIG. As shown in a and b, a flange 8 is formed to surround the outer periphery of the heat transfer tube 1 to define the pitch when the needle-like fin plates 3 are stacked. Note that the flange portion 8 does not need to extend over the entire outer circumference of the heat exchanger tube 1, but may be formed so as to be partially folded back.

Furthermore, in the portion of the metal thin plate 5 between the fitting holes 7, a mounting joint portion to the heat exchanger tube 1 is left, and the needle-like fin plate 3 is left.
The width W is approximately equal to the plate thickness t, excluding the cladding thickness of the brazing filler metal 6, and the distance g is maintained between them, in the direction perpendicular to the flow of the extra-tubular fluid, that is, the illustrated example. Now, punching is performed so as to leave needle-like fins 2a with a rectangular cross section in the vertical direction of FIG. In this case, when the needle-like fins 2 having a circular cross section formed on the needle-like fin plate 3 are stacked in a staggered arrangement when viewed from the axial direction of the heat transfer tube 1, as shown in FIG. 6a, In addition, it is necessary to form an A-arrangement needle-like fin plate 3 and a B-arrangement needle-like fin plate 3 in which the needle-like fins 2a having a rectangular cross section are shifted by 1/2 pitch. The gap g is used to determine the density of the needle fins 2 and to prevent clogging caused by the brazing material during brazing.

After the needle-like fin plates 3 are formed in this manner, a predetermined number of the needle-like fin plates 3 are stacked by passing the fitting holes 7 of the needle-like fin plates 3 through the flat heat transfer tube 1, which is a straight tube. At this time, if the needle-like fins 2 are arranged in a grid pattern (in-line arrangement) as shown in FIG. However, when stacking them in a staggered manner as shown in FIG.
Stack them alternately. Thereafter, headers 4 are connected to both ends of the heat transfer tube 1, respectively, to form a fluid flow path within the tube. After completing the assembly work of the heat exchanger, the entire heat exchanger is placed in a brazing furnace and heated. As a result, the brazing filler metal 6 clad on the needle-like fin plate 3 melts, and the needle-like fin plate 3 and the heat exchanger tube 1 are brazed together via the collar 8, and the headers 4 at both ends of the heat exchanger tube 1 are also joined. Joined by brazing. Further, the brazing material 6 on both sides of the needle-like fin 2a having a rectangular cross section
However, at this time, due to the surface tension of the filler metal 6, it flows around the four peripheries of the needle-like fin 2a, and as shown in FIG.
From the state shown in FIG. 7b, the cross section becomes approximately circular and solidifies.

The heat exchanger obtained in this way has no manufacturing restrictions compared to conventional corrugated fin type heat exchangers, so the fin pitch in the axial direction of the heat exchanger tubes (layer spacing)
Of course, the pitch of each needle fin 2 can be made extremely small, and the heat transfer area can be increased. Therefore, if the amount of heat exchanged is made equal to that of the conventional one, the heat exchanger will be small and lightweight. In addition, the shape of the fins is different from that of corrugated fins, and the fins are needle-shaped, which improves fin efficiency and has a circular cross section, so that extra-tubular fluids, such as air,
can reduce pressure loss, improving not only heat transfer performance but also overall performance.

In the above embodiments, heat transfer tubes having a flat cross section have been described, but the heat transfer tubes may have a circular or rectangular cross section, and the heat transfer tubes may not be arranged in one plane. Furthermore, if bent pipes are used in place of the headers at both ends of the heat transfer tube, a meandering intratube fluid flow path of a single heat transfer tube can be formed, and the flow velocity within the tube can be increased to improve the heat transfer coefficient within the tube.

As specifically explained above in conjunction with the embodiments, according to the present invention, by forming needle-like fins into plate shapes and stacking them, it is possible to provide fins with a small pitch without any restrictions on fin manufacturing, and at the same time The cross section of the shaped fin can be easily made circular.

Therefore, it is possible to increase the heat transfer area and suppress an increase in pressure loss, so that it is easier to manufacture a heat exchanger that is smaller, lighter, and more efficient than a heat exchanger manufactured using a conventional manufacturing method.

[Brief explanation of the drawing]

Figures 1 to 3 a and b show a conventional corrugated fin type heat exchanger. A perspective view, FIG. 3b is a cross-sectional view taken in the direction of the - arrow in a, and FIGS. The figure is a front view, FIG. 5 is a sectional view taken in the direction of the arrow in FIG. 4, FIGS. In the cross-sectional views, a shows the assembled state and b shows the completed state. FIGS. 8a and 8b are explanatory diagrams of the arrangement of needle-like fin plates, where a shows a grid pattern (in-line arrangement) and b shows a staggered pattern (staggered arrangement), respectively. In the drawings, 1 is a heat transfer tube, 2 is a needle fin (circular cross section), 2a is a needle fin (rectangular cross section), 3 is a needle fin plate, 4 is a header, 5 is a thin metal plate, 6 is a brazing material, 7 8 is a fitting hole, and 8 is a collar.

Claims (1)

[Claims] 1 A plurality of fitting holes are punched through and fitted into the heat transfer tubes according to the arrangement of the heat transfer tubes through which the fluid inside the tubes flows through a thin metal plate having brazing filler metal clad on both sides, and fluid outside the tube is inserted between these fitting holes. A needle-like fin plate is formed by forming needle-like fins with a rectangular cross section at a predetermined interval, extending along a direction perpendicular to the flow of the thin metal plate and having a width substantially equal to the thickness of the thin metal plate and a predetermined length. are fitted into the heat transfer tubes and stacked, headers or vent pipes are connected to both ends of these heat transfer tubes to form a fluid flow path within the tubes, and the brazing material is melted by heating in a brazing furnace. At the same time, the heat exchanger tube and the needle fin plate and the heat exchanger tube and the header or vent pipe are joined by brazing, and at the same time, the brazing material on both sides of the needle fin is melted and solidified, and its surface tension forms the needle fin with a circular cross section. A method for manufacturing a heat exchanger, characterized in that the heat exchanger is formed by forming a heat exchanger.