JP2003340568A - Brazing method, multilayer heat-exchanger and latent heat recovery type heat source machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the strength and corrosion resistance or the like of a bonding portion which bonds the outer peripheral edges of a pair of plate members (sheet members) together, and particularly to improve the durability of a multilayer heat-exchanger for latent heat recovery, in a brazing method, a multilayer-exchanger and a latent heat recovery type heat source machine. <P>SOLUTION: Each channel forming body 10 for a second heat exchanger 5 has a pair of plate members 20, 21 in which a channel 10a is formed. The outer peripheral edges 20a, 21a of the plate members 20, 21 are bonded together, while the peripheral edge 20a of the plate member 20 is turned into substantially a U-shape and the outer peripheral edge 21a of the plate member 21 is clamped. The first bonding portion 51 facing to the channel 40 of the bonding portion 50 is brazed with a copper-based brazing filler metal, while the second bonding portion 52 facing to the outside is brazed with a nickel-based filler metal different from the nickel-based filler metal. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a first outer peripheral edge portion inside a predetermined plate member, by bending an outer peripheral edge portion of a predetermined plate member and sandwiching an outer peripheral edge portion of another plate member with the outer peripheral edge portion. A brazing method for brazing the outer peripheral edge portions of the outer and outer sides to the outer peripheral edge portions of other plate members with different kinds of brazing materials, and a plurality of plate members each brazed by this brazing method And a latent heat recovery type heat source device using the laminated heat exchanger.

[0002]

2. Description of the Related Art Hitherto, various laminated heat exchangers each having a plurality of flow passage forming bodies each having a flat flow passage formed therein have been put to practical use. In this type of laminated heat exchanger, each flow passage forming body has a pair of plate members that form a flow passage therein, and these plate members are superposed and their outer peripheral edge portions are joined together.

When the outer peripheral edge portions of a pair of plate members are joined together, these outer peripheral edge portions are brazed with one type of brazing material such as a copper brazing material or a nickel brazing material. The copper brazing material is a brazing material having a higher strength than the nickel brazing material (for example, the withstanding voltage value of the copper brazing material is about 230 Kgf / cm ² while the withstanding voltage value of the nickel brazing material is about 155 Kgf / cm ² ). The nickel brazing material is a brazing material having higher corrosion resistance than the copper brazing material.

A conventional gas hot water supply apparatus is provided with a burner, a first heat exchanger arranged above the burner, and a laminated second heat exchanger arranged above the first heat exchanger. There is. In this gas water heater, when the burner burns the fuel gas, the combustion gas passes through the first heat exchanger and then through the second heat exchanger, and at that time, sensible heat is passed through the first heat exchanger. To give latent heat to the second heat exchanger.

In particular, the combustion gas gives latent heat to the second heat exchanger and condenses when the temperature falls below the dew point to generate drain water near the second heat exchanger. Since this drain water is strongly acidic and adheres to the second heat exchanger, it is necessary to use a second heat exchanger that is resistant to corrosion by the drain water. Further, since the fluid in the second heat exchanger has a high pressure, the second heat exchanger has a strength that can withstand this high pressure.
It also needs to be a heat exchanger.

In the laminated heat exchanger described in Japanese Patent Laid-Open No. 10-17966, a sacrificial corrosion layer is formed on one surface of each of the pair of plate members of the flow path forming member, and the pair of plate members are The sacrificial corrosion layers are superposed so as to face outward, and the surfaces opposite to the sacrificial corrosion layer are brazed, so that the joint faces both the flow path and the outside.

[0007]

In the conventional laminated heat exchanger, when the outer peripheral edge portions of the pair of plate members of the flow path forming member are brazed to each other, when a nickel brazing material is applied as the brazing material. The strength of the joint portion (the brazing material) between these outer peripheral edge portions is lower than that in the case where the copper brazing material is applied, and when the fluid in the flow passage forming body has a high pressure, the joint portion is peeled off and the flow passage is formed. The body may burst.

On the other hand, when the outer peripheral edge portions of the pair of plate members of the flow path forming body are brazed to each other, and when a copper brazing material is applied as the brazing material, the joint portion (the brazing material) between the outer peripheral edge portions is brazed. ) Is less corrosive than when nickel brazing material is applied. Especially when this laminated heat exchanger is a heat exchanger for recovering latent heat, it is necessary to use the strongly acidic drain water generated during latent heat recovery to perform the above-mentioned joining. The part is easily corroded.

As described above, when brazing the outer peripheral edge portions of the pair of plate members of the flow path forming body to each other, if only one kind of brazing material is applied, the brazing material (bonding portion) ) Has advantages such as high strength or high corrosion resistance, but has disadvantages such as low corrosion resistance or low strength, and it is difficult to improve this disadvantage.
There is a limit to increasing the durability of this heat exchanger.

In the laminated heat exchanger described in Japanese Unexamined Patent Publication No. 10-17966, the sacrificial corrosion layer is formed on one surface of each of the pair of plate members of the flow path forming member. It is not a brazing material for brazing members. When brazing the outer peripheral edge portions of the pair of plate members, only one type of brazing material is used as the brazing material, and therefore there is the same problem as described above.

A high-strength copper brazing material is used as a brazing material for brazing the outer peripheral edge portions, and it may be possible to separately coat the brazing material from the outside in order to improve corrosion resistance. Therefore, it is unavoidable that pinholes are formed, and it is difficult to improve corrosion resistance. It is also possible to braze the outer peripheral edge portions to each other on a single surface with a copper brazing material and a nickel brazing material, but the copper brazing material and the nickel brazing material are mixed, and it is difficult to obtain a remarkable effect of increasing strength and corrosion resistance. Become.

An object of the present invention is to provide a brazing method, a laminated heat exchanger, and a latent heat recovery type heat source machine, in which strength and corrosiveness of a joint portion for joining outer peripheral edge portions of a pair of plate members (plate members) to each other. Etc. to improve the durability of the laminated heat exchanger for recovering latent heat.

[0013]

A brazing method according to claim 1, wherein two or more metal plate members are superposed, and an outer peripheral edge portion of a predetermined plate member among these plate members is substantially U-shaped. A first outer peripheral edge portion inside the bent portion of the outer peripheral edge portion of the predetermined plate member and a second outer peripheral edge outer than the bent portion. The part is brazed to the outer peripheral edge of the other plate member with a different brazing material.

In this brazing method, first, two or more metal plate members are superposed on each other, and an outer peripheral edge portion of a predetermined plate member among these plate members is bent into a substantially U shape, and the outer peripheral edge portion is bent. The outer peripheral edge of the other plate member is sandwiched by. Next, the first outer peripheral edge portion inside the bent portion of the outer peripheral edge portion of the predetermined plate member and the second outer peripheral edge portion outside the bent portion are brazed to the outer peripheral edge portions of other plate members with different kinds of brazing materials. Then, these outer peripheral edge portions are joined together.

When brazing the outer peripheral edge portion of a predetermined plate member to the outer peripheral edge portions of other plate members, between the first outer peripheral edge portion of the predetermined plate member and the outer peripheral edge portion of the other plate member, and A plate-shaped brazing material may be interposed between the second outer peripheral edge portion of a predetermined plate member and the outer peripheral edge portion of another plate member, or a brazing material may be applied by spraying and interposed. You may go. The different kinds of brazing materials include copper-based brazing materials, nickel-based brazing materials,
Two types of brazing materials, such as an aluminum brazing material and a silver brazing material, may be applied.

According to this brazing method, it is possible to prevent different kinds of brazing materials from being mixed with each other, so that the joining portion between the outer peripheral edge of a predetermined plate member and the outer peripheral edge of another plate member is made of different kinds of brazing material. The material can have all the advantages (high strength (pressure resistance), high corrosion resistance, high heat resistance, etc.).
In particular, in a laminated heat exchanger for recovering latent heat, when it is applied to braze the outer peripheral edge portions of a pair of plate members of a flow path forming body, a brazing material having high strength as the different brazing material. By applying a brazing material with high corrosion resistance,
It is possible to sufficiently withstand the high pressure of the fluid in the flow path forming body and to prevent corrosion due to the strongly acidic drain water generated during the latent heat recovery as much as possible.

A brazing method according to a second aspect is the brazing method according to the first aspect, wherein one of the two different kinds of brazing materials is a brazing material having a higher strength than the other brazing material. As the other brazing material, a brazing material having a higher corrosion resistance than the one brazing material is used. A joint portion in which the outer peripheral edge portion of a predetermined plate member and the outer peripheral edge portion of another plate member are joined by brazing can have high strength and high corrosion resistance. In a laminated heat exchanger for recovering latent heat, when applied to braze the outer peripheral edge portions of a pair of plate members of the flow path forming body, the joint portion inside the bent portion has a high strength brazing material. Brazed with
The joint portion outside the bent portion is brazed with a brazing material having high corrosion resistance.

A laminated heat exchanger according to a third aspect of the present invention is a laminated heat exchanger in which a plurality of flow passage forming bodies each having a flat flow passage formed therein are laminated, wherein each flow passage forming body is a flow passage. It has a pair of plate members forming a passage therein, and an outer peripheral edge portion of one plate member of the pair of plate members is bent into a substantially U shape so that an outer peripheral edge portion of the other plate member is formed. The outer peripheral edge portions are joined together in a sandwiched state, and of the joint portions between the outer peripheral edge portions, the first joint portion facing the flow path is brazed with the first brazing material and the second outer joint portion is exposed to the outside.
The joining portion is brazed with a second brazing material different from the first brazing material.

This laminated heat exchanger is formed by laminating a plurality of flow passage forming bodies each having a flat flow passage formed therein, and each flow passage forming body forms a flow passage therein. The pair of plate members have a pair of plate members, and one plate member of the pair of plate members has an outer peripheral edge portion bent in a substantially U shape and sandwiching the other plate member outer peripheral edge portions. The parts are joined together. Of the joints between the outer peripheral edge portions, the first joint portion facing the flow path is brazed with the first brazing material, and the second joint portion facing the outside is brazing with the second brazing material different from the first brazing material. However, it is possible to prevent different kinds of brazing materials from being mixed with each other, and the first brazing material is a high-strength brazing material and the second brazing material is a brazing material having high corrosion resistance. It is possible to sufficiently withstand the high pressure of the fluid in the flow path forming body and to prevent corrosion due to the strongly acidic drain water generated during the latent heat recovery as much as possible.

In the laminated heat exchanger of claim 4, in the invention of claim 3, the first brazing material is a brazing material having a higher strength than the second brazing material, and the second brazing material is the first brazing material. It is characterized by being a brazing material having higher corrosion resistance than that of the above. 1
The joint portion between the outer peripheral edge portions of the pair of plate members can sufficiently withstand the high pressure of the fluid in the flow path forming body and can prevent the corrosion due to the strongly acidic drain water generated during the latent heat recovery as much as possible. .

According to a fifth aspect of the present invention, in the laminated heat exchanger of the fourth aspect, a copper brazing material is applied as the first brazing material and a nickel brazing material is applied as the second brazing material. It is characterized by. The first brazing material may be a brazing material having higher strength than the second brazing material, and the second brazing material may be a brazing material having higher corrosion resistance than the first brazing material.

A latent heat recovery type heat source machine according to a sixth aspect is the third aspect.
The laminated heat exchanger according to any one of 1 to 5 is used. In other words, with the laminated heat exchanger used in this latent heat recovery type heat source machine, it is possible to sufficiently withstand the high pressure of the fluid in the flow path forming body and prevent corrosion due to the strongly acidic drain water generated during latent heat recovery as much as possible. It becomes possible to remarkably improve the durability.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is an example of a case in which the present invention is applied to a gas water heater which is a latent heat recovery type heat source machine. As shown in FIGS. 1 and 2, a gas water heater 1
Includes a burner 2, a fan 3, a first heat exchanger 4 and a second heat exchanger 5, a fan 3 is arranged below the burner 2, and a first heat exchanger 4 is arranged above the burner 2. The second heat exchanger 5 is provided above the first heat exchanger 4.

A water inlet pipe 6 and a hot water outlet pipe 7 are connected to the gas water heater 1, and the water supplied from the water supply or the like through the water inlet pipe 6 is first introduced into the second heat exchanger 5 to generate the second heat. It is introduced into the first heat exchanger 4 from the exchanger 5 via the relay pipe 8, and is led out to the outside from the first heat exchanger 4 via the tap pipe 7.

Fuel gas is supplied to the burner 2 from the gas supply pipe 9, and when the fuel gas is burned in the burner 2, the combustion gas passes through the first heat exchanger 4 and then the second heat exchange. After passing through the heat exchanger 5, the sensible heat and latent heat of the combustion gas are given to the first and second heat exchangers 4 and 5, and the inside of the first and second heat exchangers 4 and 5 is thereby given. The water passing through is heated and hot water is discharged from the hot water discharge pipe 7 to the outside.

In this embodiment, the present invention is applied to the second heat exchanger 5. However, the present invention may be applied to the first heat exchanger 4. Hereinafter, the second heat exchanger 5 will be described in detail. The front and left sides of FIGS. 2 and 3 will be described as the front and left sides.

As shown in FIGS. 2 to 7, the second heat exchanger 5
Includes a plurality of flow path forming bodies 10 each having a flat flow path 10a formed therein and a plurality of external fins 11, and the plurality of flow path forming bodies 10 and the plurality of external fins 11 are alternated in the left-right direction. Is a laminated heat exchanger laminated on the
A passage 13 for the combustion gas is formed between the two flow passage forming bodies 10 that are adjacent to each other via 1. The second heat exchanger 5 is arranged inside the heat exchanger case 12, and the second heat exchanger 5 is provided.
The end plates 28 and 29 are fixed to the side wall 12a of the heat exchanger case 12 with screws.

As shown by the arrow in FIG. 4, the combustion gas is introduced laterally inward from the opening 12c formed in the rear wall 12b of the heat exchanger case 12, and the combustion gas is guided by the partition plate 14. And flows downward and passes through the plurality of passages 13 of the second heat exchanger 5 from the upper side to the lower side.
The combustion gas that has passed through the passage 13 passes through the front side of the second heat exchanger 5 and is discharged to the outside from the opening 12e formed in the front wall 12d of the heat exchanger case 12.

While the combustion gas mainly passes through the passage 13, the latent heat of the combustion gas is given to the flow passage forming body 10 directly or via the external fin 11. The combustion gas gives latent heat to the second heat exchanger 5 to condense when the temperature becomes below the dew point, and drain water is generated in the vicinity of the second heat exchanger 5. Heat exchanger case 1
The drain water generated inside 2 adheres to the second heat exchanger 5, falls on the bottom wall 12f inclined downward to the front of the heat exchanger case 12, flows along the bottom wall 12f, and from the discharge port 15 It flows down to a neutralizer (not shown).

As shown in FIGS. 4 to 8, the second heat exchanger 5
Each of the flow path forming bodies 10 is fixedly provided in the flow path 10a between the pair of plate members 20 and 21 made of stainless steel, which forms the flow path 10a therein, and between the pair of plate members 20 and 21. And an inner fin 30 made of stainless steel. The outer peripheral edge portions 20a of the plate member 20 are bent into a substantially U shape and sandwich the outer peripheral edge portion 21a of the plate member 21, and the outer peripheral edge portions 20a and 21a are joined to each other.

A hot water outlet 23 and a water inlet 22 are vertically formed at the front end portions of the plate members 20 and 21, and a flow channel 10a is formed between the plate members 20 and 21 on the rear side. The water inflow part 22 and the hot water outflow part 23 are respectively in the flow path 10a.
And the water inlet portions 22 of the adjacent flow passage forming bodies 10 are fluid-tightly communicated with each other, and the hot water outlet portions 2 of the adjacent flow passage forming bodies 10 are communicated with each other.
The three are fluid-tightly connected to each other. The water inlet port 2 in which the end plate 28 is fixed to the flow path forming body 10 at the left end of the second heat exchanger 5 and is fixed to the left end side of the end plate 28
6 and the hot water outlet port 27 are fluid-tightly connected to the water inlet portion 22 and the hot water outlet portion 23 via end plates 28, respectively.
The water inlet port 26 is connected to the water inlet pipe 6, and the hot water outlet port 27 is connected to the relay pipe 8.

The left and right sides of each of the water inlet 22 and the hot water outlet 23 are open for connection between the adjoining water inlet 22 and the hot water outlet 23, but a flow path is formed at the right end of the second heat exchanger 5. End plates 29 are fixed in contact with the water inlet 22 and the hot water outlet 23 of the body 10 to close their openings. In this way, the water supplied to the water inlet port 26 is introduced into the plurality of flow path forming bodies 10 from the water inlet portion 22, heated, and then led out of the hot water outlet portion 23, and led out of the hot water outlet port 27 to the relay pipe 8.

As shown in FIGS. 6 to 8, each flow path forming member 5
The inner fins 30 include a partition plate 31, a plurality of partition pieces 3
2. A plurality of vertical piece portions 33 and 34 are integrally formed. The inner fin 30 is, for example, a rectangular shape having a thickness substantially equal to the width between the pair of plate members 20 and 21 and slightly longer in the front-back direction in a side view when the plate-shaped base material is press-molded with a large number of cuts. And is housed in almost the entire flow path 10a.

The partition wall 31 is formed in a strip shape that is long in the front-rear direction at the central portion in the up-down direction, and the inner fin 3 is formed.
It is formed substantially parallel to the horizontal plane in the front-rear length 3/4 portion from the front end of 0. The partition wall 31 separates a wide straight rectilinear flow passage 41 from a similar wide straight rectilinear flow passage 42 adjacent to the flow passage 41, and also the U-turn portion 43.
Are formed, and the flow paths 41, 42 and the U-turn portion 43 form a flat U-shaped flow path 40. A substantially V-shaped partition portion 24 is integrally formed on the plate member 21 at the front end boundary portion of the flow channel 10a, and a corner portion of the partition portion 24 is brought into close contact with the partition wall 31 to form the flow channels 41 and 42. It is completely partitioned.

The plurality of partitions 32 partition the pair of plate members 20, 21 intermittently, and are arranged in multiple rows intermittently in the front-back direction (flow direction). Multiple vertical strips 3
3, 34 are formed so as to be continuous with the partition wall 31 and the plurality of partition pieces 32, the vertical piece portion 33 is closely attached to the plate member 20 and fixed by brazing, and the vertical piece portion 34 is closely attached to the plate member 21 and brazed. It is fixed by. A pair of strip-shaped contact portions 35 and 36 forming a part of the vertical piece portions 33 and 34 that are in close contact with the plate members 20 and 21 are integrally formed on both left and right edges of the partition wall 31 of the inner fin 30.

Now, as shown in FIG. 9, each flow path forming body 1
At 0, the outer peripheral edge portion 20a of the plate member 20 is bent into a substantially U-shape and sandwiches the outer peripheral edge portion 21a of the plate member 21.
a is joined to each other. These outer peripheral edge portions 20a, 21
Of the joint portions 50 of a, the first joint portion 51 facing the flow path 40 is brazed with the copper brazing material which is the first brazing material, and the second joint portion 52 facing the outside is different from the copper brazing material. Second
It is brazed with a nickel brazing material which is a brazing material. The copper brazing material has a higher strength than the nickel brazing material, and the nickel brazing material has a higher corrosion resistance than the copper brazing material.

Next, a brazing method for brazing the outer peripheral edge portions 20a, 21a of the pair of plate members 20, 21 of each flow path forming member will be described. First, a pair of plate members 20 and 21 are superposed, the outer peripheral edge portion 20a of the plate member 20 is bent into a substantially U shape by a press machine or the like, and the outer peripheral edge portion 21a of the plate member 21 is separated by the outer peripheral edge portion 20a. Sandwich it.

At this stage, copper brazing is performed between the first outer peripheral edge portion 20c (facing the flow path 40) inside the bent portion 20b of the outer peripheral edge portion 20a of the plate member 20 and the outer peripheral edge portion 21a of the plate member 21. A second outer peripheral edge portion 20d outside the bent portion 20b of the outer peripheral edge portion 20a of the plate member 20 (facing the outside) and the plate member 21
The nickel brazing material is interposed between the outer peripheral edge portion 21a and the outer peripheral edge portion 21a.

Here, the outer peripheral edge portion 20 of the plate member 20.
Before bending a into a substantially U shape, the first outer peripheral edge portion 20c
A plate-shaped copper brazing material may be disposed on one of the outer peripheral edge portion 21a and the copper brazing material may be applied by spraying. Further, a plate-shaped nickel brazing material may be arranged on one of the second outer peripheral edge portion 20d and the outer peripheral edge portion 21a, or a nickel copper brazing material may be applied by spraying. Then, when the brazing material is melted and then the brazing material is solidified, the first outer peripheral edge portion 20c and the outer peripheral edge portion 21a are bonded to each other, and
The outer peripheral edge portion 20d and the outer peripheral edge portion 21a are joined together.

The brazing method and the second heat exchanger 5
The action and effect of will be described. According to this brazing method, the pair of plate members 20 and 21 of each flow path forming body 10 of the second heat exchanger 5 are overlapped with each other, and the outer peripheral edge portion 20a of the plate member 20 is bent into a substantially U shape. The outer peripheral edge portion 20a sandwiches the outer peripheral edge portion 21a of the plate member 21, and the first inner portion of the outer peripheral edge portion 20a is located inside the bent portion 20b.
The outer peripheral edge portion 20c and the second outer peripheral edge portion 20d outside the bent portion 20b are brazed to the outer peripheral edge portion 21a of the plate member 21 with different kinds of copper brazing material and nickel brazing material.

1 brazed by this brazing method
According to the second heat exchanger 5 in which the plurality of flow path forming bodies 10 each having the pair of plate members 20 and 21 are laminated, the outer peripheral edge portions 20a and 21a of the pair of plate members 20 and 21 are joined to each other. Of the portion 50, the first joint portion 51 facing the flow path 40
Is brazed with copper brazing material and faces the outside
Is brazed with a nickel brazing material different from the copper brazing material, and the copper brazing material and the nickel brazing material are rarely mixed.

The copper brazing material in the first joint portion 51 has a higher strength than the nickel brazing material in the second joint portion 52, and the nickel brazing material in the second joint portion 52 is the first brazing material.
It is a brazing material having higher corrosion resistance than the copper brazing material in the joint portion 51. Therefore, the joint portion 50 including the first and second joint portions 51 and 52 can withstand the high pressure of the fluid in the flow path forming body 10 sufficiently, and the corrosion due to the strongly acidic drain water generated during the latent heat recovery is minimized. Therefore, the durability of the flow path forming body 10, that is, the second heat exchanger 5 can be significantly improved.

Regarding the brazing method, the pair of plate members 2 of each flow path forming body 10 of the second heat exchanger 5 is used.
The present invention was applied to the case where the outer peripheral edge portions 20a and 21a of 0 and 21 are joined to each other, but not limited to the flow path forming body of the heat exchanger. When the outer peripheral edge of a predetermined plate member among these plate members is bent into a substantially U shape and the outer peripheral edge of another plate member is sandwiched by the outer peripheral edge, and when these outer peripheral edge parts are brazed to each other, This may be applied, and in this case, the first outer peripheral edge portion inside the bent portion of the outer peripheral edge portion of the predetermined plate member and the second outer peripheral edge portion outside the bent portion are made of different brazing materials from other plate members. Be brazed to the outer edge.

As a result, the joint between the outer peripheral edge of a predetermined plate member and the outer peripheral edge of another plate member is made of at least two different types.
It is possible to have all of the advantages (high strength (pressure resistance), high corrosion resistance, high heat resistance, etc.) of all kinds of brazing materials. In the second heat exchanger 5 of the above embodiment, a brazing material different from the copper brazing material as the first brazing material,
A brazing material other than the nickel brazing material may be applied as the second brazing material. It should be noted that various modifications can be added and implemented without departing from the spirit of the present invention. Further, the second heat exchanger 5 may be used for a latent heat recovery type heat source device such as a floor heating device or a hot water fan heater other than the hot water supply device.

[0045]

According to the brazing method of claim 1, 2
One or more metal plate members are superposed, the outer peripheral edge of a predetermined plate member among these plate members is bent into a substantially U shape, and the outer peripheral edge part sandwiches the outer peripheral edge part of the other plate member, Since the first outer peripheral edge portion on the inner side of the bent portion and the second outer peripheral edge portion on the outer side of the folded portion of the outer peripheral edge portion of the predetermined plate member are brazed to the outer peripheral edge portions of the other plate members by different kinds of brazing materials, It is possible to prevent different kinds of brazing materials from being mixed with each other, and at the joint portion between the outer peripheral edge portion of a predetermined plate member and the outer peripheral edge portion of another plate member, the advantage (strength (pressure resistance) High performance), high corrosion resistance, high heat resistance, etc.), resulting in significantly improved durability of components such as heat exchangers having two or more plate members. It will be possible to improve.

According to the brazing method of the second aspect, one of the two different kinds of brazing materials has a strength higher than that of the other brazing material, and the other brazing material has one strength. Since a brazing material having a higher corrosion resistance than that of a brazing material is used, a joint part in which the outer peripheral edge portion of a predetermined plate member and the outer peripheral edge portion of another plate member are joined by brazing has high strength and high corrosion resistance. Can be

According to the laminated heat exchanger of the third aspect, each flow path forming member has a pair of plate members for forming a flow path therein, and one plate member of the pair of plate members is provided. The outer peripheral edge portions of the other plate member are bent in a substantially U shape and the outer peripheral edge portions of the other plate member are sandwiched, and these outer peripheral edge portions are joined to each other. Since the first joining portion is brazed with the first brazing material and the second joining portion facing the outside is brazing with the second brazing material different from the first brazing material, different kinds of brazing materials are mixed. The first brazing material is a high-strength brazing material,
By using a brazing material having a high corrosion resistance, it is possible to sufficiently withstand the high pressure of the fluid in the flow passage forming body, and to prevent corrosion due to the strongly acidic drain water generated during latent heat recovery as much as possible. As a result, the durability of the flow path forming body, that is, the laminated heat exchanger can be significantly improved.

According to the laminated heat exchanger of claim 4,
The brazing material has a higher strength than the second brazing material,
Since the brazing material is a brazing material having a higher corrosion resistance than the first brazing material, the joint between the outer peripheral edge portions of the pair of plate members can sufficiently withstand the high pressure of the fluid in the flow path forming body, and also recover the latent heat. It is possible to prevent the corrosion caused by the strongly acidic drain water which occurs occasionally.

According to the laminated heat exchanger of claim 5,
Since the copper brazing material is applied as the brazing material and the nickel brazing material is applied as the second brazing material, the first brazing material has a higher strength than the second brazing material, and the second brazing material is A brazing material having higher corrosion resistance than the first brazing material can be obtained.

According to the latent heat recovery type heat source machine of claim 6, since the laminated heat exchanger according to any one of claims 3 to 5 is used, the laminated heat exchanger used in this latent heat recovery type heat source machine is used. By the exchanger, it is possible to sufficiently withstand the high pressure of the fluid in the flow path forming body and prevent the corrosion due to the strongly acidic drain water generated during the recovery of latent heat as much as possible, and it is possible to remarkably improve the durability.

[Brief description of drawings]

FIG. 1 is a schematic view of a hot water supply device.

FIG. 2 is a side view of a main part including first and second heat exchangers.

FIG. 3 is a front view of a main part including a second heat exchanger.

FIG. 4 is a side view of a second heat exchanger.

FIG. 5 is a front view of a second heat exchanger.

6 is a sectional view taken along line VI-VI of FIG.

7 is a sectional view taken along line VII-VII of FIG.

FIG. 8 is a perspective view of inner fins of the second heat exchanger.

FIG. 9 is a vertical cross-sectional view of a joint portion between outer peripheral edge portions of a pair of plate members.

[Explanation of symbols]

1 gas water heater 5 Second heat exchanger 10 Flow path forming body 20,21 Plate member 20a, 21a outer peripheral edge 20b bent part 20c, 20d First and second outer peripheral edge portions 40 channels 50 joints 51, 52 First and second joints

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Claims (6)

[Claims] 1. A stack of two or more metal plate members, a predetermined plate member of these plate members having an outer peripheral edge portion bent into a substantially U-shape, and the outer peripheral edge portion of the other plate member having the outer peripheral edge portion. The outer peripheral edge portion is sandwiched, and the first outer peripheral edge portion inside the bent portion of the outer peripheral edge portion of the predetermined plate member and the second outer peripheral edge portion outside the bent portion are made of different kinds of brazing material from the other plate member. A brazing method characterized by brazing to the outer peripheral edge. 2. A brazing material having a higher strength than the other brazing material is used as one brazing material of the two different kinds of brazing materials, and a corrosion resistance higher than that of one brazing material is used as the other brazing material. The brazing method according to claim 1, wherein a brazing material is used. 3. A laminated heat exchanger comprising a plurality of flow passage forming members each having a flat flow passage formed therein, wherein each of the flow passage forming members forms a pair of flow passages therein. A plate member, and one plate member of the pair of plate members has an outer peripheral edge portion bent into a substantially U shape and sandwiching the outer peripheral edge portion of the other plate member. Of the outer peripheral edge portions, the first joining portion facing the flow path is brazed with the first brazing material, and the second joining portion facing the outside is different from the first brazing material. A laminated heat exchanger characterized by being brazed with a second brazing material. 4. The first brazing material is a brazing material having a higher strength than the second brazing material, and the second brazing material is a brazing material having a higher corrosion resistance than the first brazing material. 3. The laminated heat exchanger according to item 3. 5. The laminated heat exchanger according to claim 4, wherein a copper brazing material is applied as the first brazing material, and a nickel brazing material is applied as the second brazing material. 6. A latent heat recovery type heat source machine, characterized by using the laminated heat exchanger according to any one of claims 3 to 5.