JPH0674678A - Lamination type heat exchanger and manufacture thereof - Google Patents

Abstract

PURPOSE:To achieve a higher heat transfer rate on the side of a fluid by forming such a narrow rib that is not made available by the present pressing technique. CONSTITUTION:Inner fins 10 arranged in a flat pipe 9 is made up of a lamination of one pair of rib bodies which comprise two vertical ribs 11a arranged parallel at a fixed interval and slant ribs 11b arranged askew parallel at a fixed interval between the two vertical ribs 11a. The rib bodies are made by working such as cutting or blanking so that the ribs 11a and 11b become rectangular in the shape of the cross section thereof, that is, planar parts exist on the head parts of ribs 11a and 11b on the surface and rear sides of the rib bodies.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated heat exchanger in which flat tubes and fins are alternately laminated.

[0002]

2. Description of the Related Art Conventionally, in a vehicle refrigeration cycle, as a refrigerant condenser or evaporator, a laminated type in which flat tubes forming a refrigerant flow path and fins for improving heat transfer on the air side are alternately laminated. Heat exchangers are often used. In this laminated heat exchanger, in order to promote heat transfer on the refrigerant side, as shown in FIG. 10, a pair of metal forming plates 102 and 103 on which a large number of ribs 101 are pressed are stacked so as to face each other. A flat tube 100 joined by brazing is used.

[0003]

The above flat tube with ribs 100 is provided with the ribs 101 when the gas-liquid two-phase refrigerant flows through the inside of the flat tube 1 with the ribs.
00 has a large effect in promoting heat transfer at the base surface (a flat surface portion where the rib 101 is not provided), but the heat transfer coefficient of the surface itself of the rib 101 is low and the effect as an enlarged heat transfer surface is small. . Further, the heat transfer coefficient on the surface of the rib 101 is smaller than that of the base surface, and especially when the dryness of the refrigerant is high, the rib 101
It has been clarified that the heat transfer coefficient on the surface is remarkably reduced with respect to the basal surface ("Refrigerant flow and evaporation heat transfer in a ribbed flat flow path": Japan Society of Mechanical Engineers paper No. 90-0.
983B [1991, 4], and "Promotion of heat transfer on refrigerant side of plate fin evaporator for car air conditioner": Paper No. 910-62-1537 [199
1, 10, 17 Nagoya])).

Therefore, it is considered to improve the overall heat transfer coefficient by reducing the width b of the rib 101 to reduce the surface area of the rib 101 while maintaining the heat transfer promotion effect on the base surface by the rib 101. To be However, rib 10
When the width of 1 is reduced, the current pressing technology
There is a limit to creating a rib shape with good brazing,
It is difficult to form a flat surface on the head of the rib 101. As a result, there arises a problem that the brazing property between the facing ribs 101 is deteriorated. The present invention has been made based on the above circumstances, and an object thereof is to form a narrow rib that cannot be formed by the current press working technology, thereby improving the heat transfer coefficient on the fluid side. In the provision of exchangers.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a laminated heat exchange system in which flat tubes forming fluid passages for heat exchange and fins for heat transfer are alternately laminated. In the container, the flat tube is provided with a flat cross-sectional shape, and a flat tube in which a fluid flows in the longitudinal direction, and an inner fin that is inserted into the flat tube to disturb the flow of the fluid in the flat tube The inner fin comprises a pair of rib bodies composed of a plurality of ribs arranged obliquely parallel to the longitudinal direction of the flat tube, and the ribs are superposed so that the ribs intersect each other,
Technical means is that a flat surface portion is formed on each rib on both sides of each rib body. Further, the inner fin is formed by cutting or punching a metal flat plate to form the pair of rib bodies, and temporarily stacking the rib bodies so that the ribs intersect each other, and then the flat plate It is manufactured by inserting into a pipe and brazing.

[0006]

The laminated heat exchanger of the present invention having the above structure is
The inner fin inserted into the flat tube has a flat surface on each rib on both sides of each rib body. Therefore, when the inner fins are formed by stacking the rib bodies, ribs that intersect with each other are joined together. Will be easier. For example, in the case of brazing and joining each rib body, good brazing properties can be obtained by using the plane portions of the ribs that intersect with each other as brazing surfaces.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment in which the laminated heat exchanger of the present invention is used as a refrigerant evaporator will be described with reference to FIGS. As shown in FIG. 6, the refrigerant evaporator 1 of the present embodiment is a drone cup type in which a large number of flat tubes 2 and fins 3 for heat transfer are alternately laminated, and heat exchange between the refrigerant and blown air. Heat exchange section 4, a pair of refrigerant tanks 5 and 6 provided above and below the heat exchange section 4, an inlet pipe 7 communicating with the upper refrigerant tank 5, and an outlet pipe communicating with the lower refrigerant tank 6. Have eight. The flat tube 2 includes a flat tube 9 (see FIG. 2) formed by joining a pair of flat metal forming plates 9a and 9b to each other, and an inner fin 10 (see FIG. 3) arranged in the flat tube 9. Composed. The flat tube 9 forms a refrigerant flow path through which the refrigerant flows in the longitudinal direction (vertical direction in FIG. 6), and communicates with the refrigerant flow path to form an upper tank portion that forms part of the refrigerant tanks 5 and 6. 5a and the lower tank portion 6a are integrally formed.

As shown in FIGS. 4 and 5, the inner fin 10 has two vertical ribs 11a arranged in parallel with each other at a predetermined interval (a width that allows the flat tube 9 to be inserted into the flat tube 9 without any gap), and these two ribs.
Each of the vertical ribs 11a is formed of a pair of rib bodies 11 composed of a plurality of diagonal ribs 11b which are diagonally arranged in parallel with each other at a fixed interval. They are formed so as to overlap each other (see FIG. 3). The rib body 11 is made of aluminum clad material so that the ribs 11a and 11b have a rectangular cross-sectional shape (see FIGS. 4 and 5), that is, on the front side and the back side of the rib body 11. Ribs 11a, 11
It is manufactured by processing such as cutting or punching so that a flat portion exists on b.

Now, a method of manufacturing the flat tube 2 will be described. First, the flat tube 9 is assembled by facing a pair of metal forming plates 9a and 9b clad with a brazing material. Next, after forming the pair of rib bodies 11 by processing such as cutting or punching as described above, as shown in FIG. 3, the rib bodies 11 are stacked so that the diagonal ribs 11b of the rib body 11 intersect with each other. In addition, the appropriate places are temporarily attached by welding or the like. Then, the temporarily attached inner fins 10 are inserted into the flat tubes 9, and the rib bodies 11 are brazed by integral brazing, and the inner fins 10 and the flat tubes 9 are brazed.

In the flat tube 2 in which the inner fins 10 are arranged in the flat tubes 9, the liquid refrigerant flowing in the flat tubes 9 flows along the respective oblique ribs 11b of the inner fins 10, so that the inner wall surface of the flat tubes 9 is made. A thin liquid film spreads evenly on top,
As a result, the heat transfer coefficient on the refrigerant side is improved. The effect of promoting heat transfer by the oblique ribs 11b is great on the base surface (flat surface portion without ribs) of the flat tube 9, but the heat transfer coefficient on the surface of the oblique ribs 11b is smaller than that on the base surface. Further, since the heat transfer coefficient of the surface itself of the oblique rib 11b is low, the effect as an enlarged heat transfer surface by providing the oblique rib 11b is small. Therefore, the heat transfer coefficient on the refrigerant side can be further increased by reducing the surface area of the oblique rib 11b, that is, by reducing the rib width a (see FIGS. 4 and 5).
In view of this, in this embodiment, the flat tube 9 and the inner fin 10 are formed separately, so that the inner fin 10 can be manufactured by cutting or punching, and as a result, the rib width a is reduced (for example, 2 mm or less). It is possible. Further, even if the rib width a is reduced, a flat portion can be left on the heads of the ribs 11a and 11b to be the brazing surface, so that good brazing performance can be secured even if the rib width a is small. You can In this way, by reducing the rib width a without deteriorating the brazing property, the diagonal rib 1
Since the surface areas of 1a and 11b can be reduced, the heat transfer coefficient on the refrigerant side can be further improved while the effect of promoting heat transfer at the base bottom surface of the flat tube 9 by the inner fins 10 is maintained.

Further, in the conventional flat tube 100 shown in FIG. 10, a large flow of turbulence disturbed by the ribs 101 (shown by a broken line A in FIG. 10) and the flat tube 10 are shown.
Flow with little turbulence along both ends in 0 (broken line B in FIG. 10)
, And the heat transfer performance deteriorates on both end sides with little turbulence. On the other hand, in the present embodiment, the vertical ribs 11a and the slanted ribs 11b are integrally formed, and the vertical ribs 11a are brazed to both ends of the flat tube 9 without any gaps, whereby the flat tube All of the refrigerant flowing in 9 becomes a turbulent flow, and the heat transfer performance is not deteriorated. Even in the conventional flat tube 100, the rib 1 is formed by connecting the ribs 101 to both ends of the flat tube 100.
It is possible to eliminate the gap with 01, but when the rib 101 is formed in this way, the metal forming plates 102, 1
Since there is a possibility that warp will occur in 03 and it will be impossible to braze,
In reality, as described above, a large turbulence flow and a small turbulence flow occur. Further, when the ribs 101 are provided on the metal forming plates 102 and 103 by press working, the depressions of the ribs 101 are formed on the outer wall surface of the flat tube 100, so that the contact area with the heat transfer fins 3 is reduced. On the other hand, in the present embodiment, since the outer wall surface of the flat tube 9 is a flat surface without any depression, it is advantageous in maintaining the heat transfer area on the air side. Then, as in this embodiment,
By forming the flat tube 9 and the inner fin 10 as separate bodies, various pressing dies that have been used conventionally are not required.

FIG. 7 shows a second embodiment of the present invention. FIG. 7 is a plan view of the inner fin 10. The inner fin 10 of this embodiment is composed of only the diagonal ribs 11b (a shape in which the left and right vertical ribs 11a of the inner fin 10 shown in the first embodiment are scraped off). The cross-sectional area of the refrigerant flow path of the tube 2 can be increased. [Modification] In the above-described embodiment, the ribs 11a and 11b are formed so that the cross-sectional shape is rectangular. However, the ribs 11a and 11b are trapezoidal as shown in FIG. 8 or the side surfaces are curved as shown in FIG. It may be a cross-sectional shape. Further, although the refrigerant evaporator 1 of the drone cup type in which the flat tube 9 and the upper and lower tank portions 5a and 5b are integrated is shown, a pair of tanks provided separately from the flat tube 2 are provided at both ends of each flat tube 2. It may be a multi-flow type arranged in the section.

[0013]

In the laminated heat exchanger of the present invention, the flat tubes and the inner fins are formed as separate members, so that the width of the ribs forming the inner fins can be reduced in the state where the rib head has a flat portion. It becomes possible. As a result, the surface area of the rib can be reduced and the heat transfer coefficient on the fluid side can be further improved without deteriorating the brazing property.

[Brief description of drawings]

FIG. 1 is a perspective view of a flat tube according to a first embodiment of the present invention.

2 is a perspective view of a flat tube forming the flat tube of FIG. 1. FIG.

FIG. 3 is a perspective view of inner fins forming a flat tube together with the flat tube of FIG.

FIG. 4 is a plan view of a rib body forming the inner fin of FIG.

5 is a plan view of a rib body forming the inner fin of FIG. 3. FIG.

FIG. 6 is a front view of the refrigerant evaporator according to the first embodiment.

FIG. 7 is a plan view of an inner fin according to a second embodiment of the present invention.

FIG. 8 is a cross-sectional view of a rib according to a modified example of this embodiment.

FIG. 9 is a cross-sectional view of a rib according to a modified example of this embodiment.

FIG. 10 is a perspective view of a flat tube according to a conventional technique.

[Explanation of symbols]

 1 Refrigerant evaporator (laminated heat exchanger) 2 Flat tube 3 Fin 9 Flat tube 10 Inner fin 11 Rib body 11a Vertical rib (rib) 11b Oblique rib (rib)

Claims (2)

[Claims] 1. A laminated heat exchanger in which flat tubes forming heat exchange fluid passages and fins for heat transfer are alternately laminated, wherein the flat tubes have a flat cross-sectional shape. , A flat tube in which a fluid flows in the longitudinal direction, and an inner fin inserted in the flat tube to disturb the flow of the fluid in the flat tube, the inner fin being in the longitudinal direction of the flat tube. A pair of rib bodies, each of which is composed of a plurality of ribs arranged diagonally parallel to each other, are stacked so that the ribs intersect each other, and a flat surface portion is formed on each rib on both surface sides of the rib body. The laminated heat exchanger characterized in that 2. The inner fin is formed by cutting or punching a metal flat plate to form the pair of rib bodies, and the rib bodies are superposed and temporarily attached so that the ribs intersect each other. 2. The flat tube is manufactured by being integrally brazed by being inserted into the flat tube.
A method for manufacturing the laminated heat exchanger described.