JP3290860B2 - Heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger used for a water heater or the like, and more particularly, to a heat exchanger in which heat collecting fins arranged in a flow passage for a heat medium such as combustion gas are stacked in a line. The present invention relates to a brazing structure for a heat exchanger brazed to a casing constituting a main body.

[0002]

2. Description of the Related Art Conventionally, as this type of heat exchanger, FIG.
Are well known. This figure 5
The heat exchanger 50 shown in FIG. 3 has a direction intersecting (perpendicular to) the direction of the flow of the combustion gas flowing through the casing 52 from the bottom to the top at a position near the upper end opening in the casing 52 having the upper and lower ends open. Many fins 54, 5
4 are lined up, and the water supply pipe 56 through which water flows
Heat collecting fins 54, 54 arranged in a row from one side wall 2
Are drawn out from the opposite wall of the casing 52 so as to penetrate through the heat collecting fins 54, 54... By repeating this process several times and arranged in a zigzag manner.

According to the heat exchanger having such a structure, the heat of the combustion gas flowing through the casing 52 is transferred to the heat collecting fins 5.
The water flowing through the water supply pipe 56 is heated by the recovered heat through the wall of the water supply pipe 56, so that tap water with a desired hot water temperature can be obtained.

Thus, in the heat exchanger having such an external appearance, the heat collecting fins 54, 54, and the inner wall surface of the casing 52 are generally formed of a metallic material (such as a copper plate). This brazing structure is generally known to have a structure as shown in FIG. That is, in the one shown in FIG. 6, bent pieces 58 are formed at both end edges of the heat collecting fins 54, 54.
8 and the inner wall surface of the casing 52 are brazed over the entire surface of the bent piece 58.

[0005]

However, in the structure shown in FIG. 6, not only the wall surface of the casing 52 near the upper end opening, but also the lower opening side of the casing 52, that is, upstream of the combustion gas. The heat collecting fins 54, 5 are provided up to the skirt 60 side of the casing 52 located on the side.
4, and the casing 52
On the skirt 60 side, the heat collecting fins 54 themselves are heated to a high temperature due to the high temperature of the combustion gas, and the heat transfer fins 54 are brazed to the casing 52 to improve the heat transfer. The temperature on the side became high and durability was concerned.

[0006] As means for solving this,
The structure shown in FIG. 7A is also conceivable. This is because the bent pieces formed at both end edges of the heat collecting fin 54 are formed into upper half bent pieces 64a and lower half bent pieces 64b, and the upper half bent pieces 64a are formed on the inner wall surface of the casing 52. And the lower half bent piece 64b is provided in a non-contact state separated from the casing 12.

However, with the structure shown in FIG. 7A, the skirt 60 side of the casing 52 is not in contact with the lower half-bent piece 64b which is the high-temperature side of the heat collecting fin 54, so that the temperature is low. However, the brazed portion above the boundary (point A in the figure) between the upper half-folded piece 64a and the lower half-folded piece 64b, that is, the upper half-folded piece 64a side, does not rise so much. In order to be displaced outward and to be displaced inward at the lower non-contact portion, that is, the lower half-bent piece 64b side, an extremely bent state as shown in FIG. Deform. As a result, stress concentration occurs at point A of the casing 12, which is a boundary between the upper half-folded piece 64a and the lower half-folded piece 64b, and cracks and thermal strains particularly occur on the skirt side of the casing exposed to the high temperature of the combustion gas. Alternatively, dents and the like may be formed on the inside, and in this case, durability is also concerned.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to suppress a rise in temperature of a casing through which a heat medium such as combustion gas flows, particularly on a skirt side. Another object of the present invention is to provide a heat exchanger excellent in durability, in which the concentration of thermal stress generated in a casing is reduced.

[0009]

In order to achieve this object, a heat exchanger according to the present invention is provided in a casing through which a heat medium such as a combustion gas flows, at regular intervals in a direction intersecting the flow direction of the heat medium. In a structure in which a large number of heat collecting fins are arranged in a stack in a stack and the edges of these heat collecting fins are brazed to the inner wall surface of the casing, the heat collecting fins are bent at the edges thereof. To the middle of the end face
-A notch is provided to prevent the flow of material, and the notch
The end face where the flow is blocked is brought into contact with the inner wall of the casing.
The gist of the invention is to gradually separate from the inner wall surface .

[0010]

According to the heat exchanger of the present invention having such a configuration, the heat medium such as combustion gas flows through the casing, so that the heat of the heat medium is recovered by the heat collecting fins. Part of the heat recovered from the fins is also transmitted to the casing, but if a notch is formed in the middle of the edge of the heat collecting fin to prevent the flow of the brazing material when brazing, The edge of the fin is divided into a brazed portion and a non-braded portion (an end face whose flow is blocked by the notch) by the “notch”. Non-brazing part
Of the parts that contact the inner wall surface of the casing,
Heat transfer to the casing is suppressed compared to the
The rise is suppressed. This prevents overheating of the casing.
It is. The non-brazed part is also the inner wall of the casing.
By gradually separating them, it is not
The difference between the temperature distribution and the
Cracking, thermal distortion, or
Avoids sinking due to thermal deformation
can do. That is, thermal stress concentration is reduced
Will be.

[0011]

[0012]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a heat exchanger according to a first embodiment of the present invention. FIG. 2 also shows FIG.
3 is an external perspective view of the heat collecting fin, and FIG. 3 is an enlarged view of a main part of the heat exchanger shown in FIG.

As shown in the figure, a heat exchanger 10 according to the first embodiment has a large number of copper heat collecting fins inside a rectangular box-shaped copper casing 12 having upper and lower ends opened near the upper edge of an opening edge. Are arranged in a laminating manner. The heat collecting fins 14, 14,... Are bent at both end edges joined to the casing 12, and are provided with cutouts 16 in the middle of the bent pieces to prevent the flow of the brazing material.
The upper half bent piece 18a and the lower half bent piece 18b are formed on both end edges of the heat collecting fin 14, respectively.

When the heat collecting fins 14 are brazed to the casing 12, the low bar materials 20 (in FIG. 1, phantom lines) are formed along the contact edge of the heat collecting fins 14 with the casing 12 on the upper half-bent piece 18 a. Are inserted in a brazing furnace, and the heat collecting fins 14, 14,... Are melted in the brazing furnace. It is brazed to the inner wall surface of the casing 12. At this time, the brazing material flows into the contact surface between the upper half bent piece 18a of the heat collecting fin 14 and the casing 12,
Since the flow stops at the notch 16, the upper half-folded piece 18a is brazed to the surface of the casing 12, but the lower half-folded piece 18a is
b is not brazed because the brazing material does not flow, and only contacts the inner wall surface of the casing 12 on the skirt 22 side.

In FIGS. 1 to 3, a through hole 26 of a water supply pipe 24 is formed by punching in the plate surface of the heat collecting fin 14.
An upright edge 28 for joining with the water supply pipe 24 by the brazing material is provided around the inner periphery of the inner surface, and a spacer piece 30 for maintaining a space interval between the heat collecting fins 14, 14,. Are formed in an appropriate number. Further, the insertion hole 26
The brazing rod material is also formed with a through hole 32, and the brazing rod material inserted into the through hole 32 during the brazing operation in the brazing furnace is melted, so that the water supply pipe 24 and the heat collecting fins are formed. The brazing material also flows between the through-hole 26 and the rising edge 28 of the insertion hole 26, and the heat collecting fins 14 are brazed around the water supply pipe 24.

According to the heat exchanger thus constructed, the combustion gas of the combustion burner is supplied from the casing 12 through the opening of the casing 12 shown in FIG.
The heat of the combustion gas is recovered by the heat collecting fins 14 when the gas is introduced into the inside and flows toward the upper opening, and the recovered heat heats the water flowing through the water supply pipe 24. A part of the heat is also transmitted to the casing 12 through the upper half bent pieces 18a and the lower half bent pieces 18b of the heat collecting fins 14, 14,. At this time, since the upper half bent piece 18a of the heat collecting fin 14 is brazed to the casing 12, a relatively large amount of heat is transmitted, but the lower half bent piece 18b and the casing 12 are only in contact with each other. The heat transfer is poor because it is not brazed, and the temperature does not rise so much. Therefore, the temperature rise on the skirt 22 side of the casing 12 is smaller than that in the upper half of the casing 12.

The upper half bent piece 18a of the heat collecting fin 14
Attempts to displace the casing 12 outward due to the temperature rise, and also attempts to displace the casing 12 outward since the lower half-bent piece 18b is also in contact with the casing 12, and the displacement direction of the casing 12 is Upper half folded piece 18a
Is in the same direction as the lower half-bent piece 18b, so that the thermal stress concentration at the boundary between the brazed portion and the non-braded portion of the casing 12 is reduced.

FIG. 4 is a sectional view of a heat exchanger according to a second embodiment of the present invention. In the heat exchanger 40 of this embodiment, lower half-folded pieces 44b formed by bending both ends of the heat collecting fins 42 together with upper half-folded pieces 44a are formed in an inwardly tapered shape gradually separated from the skirt 22 of the casing 12. Is formed.

With this configuration, when the heat collecting fins 42 are brazed to the casing 12, the upper half bent piece 44 a of the heat collecting fins 42 and the inner wall surface of the casing 12 are in contact with each other. The flow of the brazing material is at the boundary between the upper half-bent piece 44a of the heat collecting fin 42 and the lower half-bent piece 44b separated from the inner wall surface of the casing 12 (point B in the figure). Stop at.

Therefore, according to the heat exchanger 40 configured as described above, the combustion gas flowing through the casing 12 is recovered by the heat collecting fins 42, and a part of the recovered heat is in the upper half of the heat collecting fins 42. The casing 12 is provided via the bent piece 44a.
However, since the heat collecting fins 42 and the casing 12 are in contact only with the upper half-folded piece 44a and are separated from the lower half-folded piece 44b, the contact area is not large. The amount of heat transferred from the heat fins 42 to the casing 12 is not large, and the casing 12, especially the skirt 22 side, is not heated to a very high temperature.

The upper half bent piece 44a of the heat collecting fin 42
Is joined to the casing 12 so that the casing 12
Is applied to move the casing 12 inward, and the lower half-bent piece 44b of the heat collecting fin 42 is separated from the casing 12, so that a force acts to displace the casing 12 inward. The lower half-bent piece 44b of the heat collecting fin 42 is formed in a tapered shape that is gradually separated from the lower end edge of the upper half-fold piece 44a, so that the casing 12 may be deformed but along the tapered surface. It will be gently deformed.
Therefore, no extreme bending occurs at the boundary (point B in FIG. 4) between the upper half-folded piece 44a and the lower half-folded piece 44b of the heat collecting fin 42, and the thermal stress concentration at that portion is reduced. Since the mitigation is alleviated, it is possible to prevent the casing 12, particularly the skirt 22 side, which is easily affected by the heat of the high-temperature combustion gas, from being subjected to cracks, extreme thermal distortion, and the like. It should be noted that the present invention is not limited to the above-described embodiment at all, and it is needless to say that various modifications and improvements can be made without departing from the spirit of the present invention.

[0022]

As is apparent from the above description,
ADVANTAGE OF THE INVENTION According to the heat exchanger of this invention, in the structure in which the heat collecting fin was brazed to the casing, it bent to the edge of the heat collecting fin.
The flow of the brazing material when brazing is applied to the middle of the formed end face
A notch is provided to prevent flow.
The contacted end face gradually contacts the inner wall surface of the casing.
Because it is separated from the inner wall, it stops the flow
The temperature rise of the casing can be suppressed by
The temperature distribution is moderated by gradually separating
Thermal stress concentration on the casing can be reduced.
You. Therefore, the heat exchanger of the present invention has excellent durability.
Become.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a joint portion between a heat collecting fin and a skirt of a heat exchanger according to one embodiment of the present invention.

FIG. 2 is an external perspective view of a heat collecting fin in the heat exchanger shown in FIG.

FIG. 3 is an enlarged sectional view of a main part of the heat exchanger.

FIG. 4 is a cross-sectional view showing a joint between a heat collecting fin and a skirt of a heat exchanger according to another embodiment of the present invention.

FIG. 5 is an external perspective view of a heat exchanger of this type, which is conventionally generally known.

FIG. 6 is a cross-sectional view showing one example of a joint portion between a heat collecting fin and a skirt of a conventional heat exchanger.

FIG. 7 is a cross-sectional view showing another example of a joining portion between a heat collecting fin and a skirt of a conventional heat exchanger.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Heat exchanger 12 Casing 14 Heat collecting fin 16 Notch 18a Upper half bent piece 18b Lower half bent piece 20 Row bar 22 Skirt 24 Water pipe 40 Heat exchanger 42 Heat collecting fin 44a Upper half bent piece 44b Lower Half-folded piece

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) F28F 1/00-1/44 B23K 1/00 330 F24H 9/00

Claims (1)

(57) [Claims] To 1. A direction thermal medium such as a combustion gas intersects the flow direction of the heat medium in the casing to flow through a large number of sheets of the heat collecting fins at a constant interval is arrayed arranged in layers,
In a heat exchanger in which the edges of these heat collecting fins are brazed to the inner wall surface of the casing, the edge of the heat collecting fins
Of brazing material when brazing to the middle part of the bent end face
Provide a notch to block the flow, and the notch
The blocked end surface gradually contacts the inner wall surface of the casing.
Next , a heat exchanger characterized by being separated from the inner wall surface .