WO2010116730A1

WO2010116730A1 - Heat exchanger and method for producing the same

Info

Publication number: WO2010116730A1
Application number: PCT/JP2010/002523
Authority: WO
Inventors: 加藤功; 真崎武
Original assignee: サンデン株式会社
Priority date: 2009-04-07
Filing date: 2010-04-07
Publication date: 2010-10-14
Also published as: JP2010243078A

Abstract

Provided are a heat exchanger and a method for producing the same, wherein the pressure resistance of the heat exchanger can be improved, while the cost of producing the heat exchanger can be reduced. A heat exchanger (1) in which heat-transfer pipes (4) inserted through laminated fins (2) are connected together by an angled pipe (6), wherein the heat-transfer pipes are provided with a bonding part (10) which is bonded with respect to the laminated fins after insertion through the laminated fins; and a junction part (12) which is formed at one end (4a) of the heat-transfer pipe, and inserted into the angled pipe and joined by brazing. The outer peripheral surface (12a) of the junction part is substantially flush with the outer peripheral surface (10a) of the bonding part.

Description

Heat exchanger and manufacturing method thereof

The present invention relates to a heat exchanger and a manufacturing method thereof, and more particularly, to a heat exchanger suitable for use in a heat pump water heater and a manufacturing method thereof.

This type of heat exchanger is known in which heat transfer tubes inserted through laminated fins are connected by a bend tube, and the heat transfer tubes are in close contact with the laminated fins after being inserted through the laminated fins. A close contact portion and a joint portion formed at an end portion of the heat transfer tube, to which a bend tube is inserted and brazed are provided.
The joint portion is formed by expanding the end portion of the heat transfer tube at a relatively large tube expansion rate to form a tube expansion portion in the heat transfer tube, and then inserting a bend tube into the tube expansion portion and brazing and joining. Is known (see, for example, Patent Document 1).

Also, a tube expansion device for forming the tube expansion portion is disclosed (for example, see Patent Document 2).

JP 2001-56165 A JP 2008-1000025 A

However, in each of the above-described conventional techniques, the pressure resistance of the heat transfer tube is reduced due to the thinning of the end portion accompanying the expansion of the end portion of the heat transfer tube. In particular, when a natural refrigerant such as carbon dioxide that is in a supercritical state is used as the refrigerant of the heat exchanger, there is a problem that the pressure resistance performance of the heat exchanger cannot be ensured because high pressure acts on the heat transfer tubes.

Moreover, in each said prior art, in the manufacturing process of a heat exchanger, between the adhesion process for forming the said contact part in a heat exchanger tube, and the joining process for forming the said junction part in a heat exchanger tube, Since the pipe expansion process for forming the said pipe expansion part using the pipe expansion apparatus which is disclosed by patent document 2 is required, there exists a problem that the manufacturing cost of a heat exchanger increases.
The present invention has been made in view of such problems, and provides a heat exchanger that can improve the pressure resistance performance of the heat exchanger and reduce the manufacturing cost of the heat exchanger, and a method for manufacturing the heat exchanger. The purpose is to do.

In order to achieve the above object, the heat exchanger according to claim 1 is a heat exchanger in which heat transfer tubes inserted through the laminated fins are connected by a bend tube, and the heat transfer tubes are inserted through the laminated fins. A contact portion that is in close contact with the laminated fin later, and a joint portion that is formed at an end portion of the heat transfer tube and is brazed and joined, and the outer peripheral surface of the joint portion is the outer peripheral surface of the close contact portion It is characterized by the fact that they are almost flush with each other.

The invention of claim 2 is characterized in that, in claim 1, carbon dioxide refrigerant is circulated in the heat transfer tube.
Furthermore, the heat exchanger manufacturing method according to claim 3 is a heat exchanger manufacturing method in which heat transfer tubes inserted through the laminated fins are connected to each other by a bend tube, and the heat transfer tubes are inserted into the laminated fins and then laminated fins. A close contact process for forming a contact portion on the heat transfer tube, and after the close contact step, a bend tube is inserted into the end portion of the heat transfer tube and brazed and joined to the outer peripheral surface of the close contact portion. And a bonding step of forming a bonding portion having a flush outer peripheral surface.

According to the heat exchanger of the present invention of claim 1, the outer peripheral surface of the joint portion of the bend tube in the heat transfer tube is substantially flush with the outer peripheral surface of the close contact portion of the heat transfer tube, so that the joint portion is formed of the heat transfer tube. Heat exchange is possible because the end is formed without being expanded, and the heat transfer tube can be prevented from rupturing due to refrigerant pressure due to the reduced pressure strength of the heat transfer tube due to thinning of the end of the heat transfer tube accompanying expansion. The pressure resistance performance of the vessel can be improved.

According to the invention of claim 2, since the carbon dioxide refrigerant is circulated through the heat transfer tube, the high pressure of the carbon dioxide refrigerant that is in a supercritical state acts on the heat transfer tube. Therefore, it is possible to more effectively prevent the heat transfer tube from rupturing due to a decrease in pressure resistance of the heat transfer tube.
Furthermore, according to the manufacturing method of the heat exchanger of this invention of Claim 3, the adhesion process which makes a heat transfer tube closely_contact | adhere to a lamination fin after inserting a heat transfer tube into a lamination fin, and an adhesion process Thereafter, a bending step is inserted into the end portion of the heat transfer tube and brazed and joined to form a joint portion having an outer peripheral surface substantially flush with the outer peripheral surface of the close contact portion at the end portion. Thereby, since the pipe expansion process which expands the edge part of a heat exchanger tube becomes unnecessary, and the number of processes in the manufacturing process of a heat exchanger can be reduced, the manufacturing cost of a heat exchanger can be reduced.

It is the figure which showed roughly the principal part of the heat exchanger which concerns on one Embodiment of this invention. (a) The figure which showed the insertion process of the heat exchanger tube in the manufacturing process of a heat exchanger, (b) The figure which expanded and showed the principal part of Fig.2 (a). (a) The figure which showed the state which the insertion process of the heat exchanger tube among the manufacturing processes of a heat exchanger was completed, (b) The figure which expanded and showed the principal part of Fig.3 (a). (a) The figure which showed the adhesion process of the heat exchanger tube in the manufacturing process of a heat exchanger, (b) The principal part of FIG. 2 (a) was expanded and the state in which the heat exchanger tube was adhered was shown. FIG. (a) Diagram showing the process of joining the bend pipe to the heat transfer pipe in the manufacturing process of the heat exchanger, (b) Enlarging the main part of FIG. 2 (a) and joining the bend pipe to the heat transfer pipe FIG. 3C is a diagram showing a state in which the bend pipe is joined to the heat transfer pipe from the state of FIG. 2B. It is the characteristic figure which compared the pressure loss with respect to the component ratio of a refrigerant | coolant and a circulation flow rate with a carbon dioxide refrigerant | coolant and a fluorocarbon refrigerant | coolant (Source: C.Y.Park, P.S.Hrnjak / International Journalourof Refrigeration 30 (2007) 166-178).

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows the main part of the finned tube heat exchanger of the present invention.
For example, the heat exchanger 1 is inserted in a heat pump circuit in which a carbon dioxide refrigerant circulates in a heat pump water heater, and includes a laminated fin 2, a plurality of heat transfer tubes 4, and a plurality of bend tubes 6.

The laminated fin 2 is configured by laminating a plurality of plate-like fins 2 a at a predetermined interval, and has a plurality of insertion tubes 8 through which the heat transfer tubes 4 are inserted. The fins 2 a are outer peripheral surfaces 8 a of the insertion tubes 8. Is erected.
The heat transfer tube 4 is a so-called hairpin tube formed by bending a copper tube or the like into a substantially U shape, and has an outer diameter D _{OUT1 of} about 5 mm and a wall thickness t ₁ of about 0.32 mm. The refrigerant flows in the direction of the arrow in FIG.

On the other hand, the bend tube 6 is a so-called U-bend that connects adjacent end portions 4 a of different heat transfer tubes 4, and is about 4.6 mm to about 4.7 mm slightly smaller than the heat transfer tube 4. It has an outer diameter D _OUT2 and a wall thickness t ₂ of about 0.32 mm.
Further, the heat transfer tube 4 includes a contact portion 10 that is a portion that is in close contact with the inner peripheral surface 8 b of the insertion tube 8 after being inserted into the laminated fin 2, that is, the insertion tube 8, and an end portion of the heat transfer tube 4. 4a, the joint 12 is formed by inserting the bend pipe 6 into the joint, and the joint 12 is bent by the brazing part 14 formed by brazing the open end surface of the end 4a to the vent pipe 6. Joined to the tube 6.

Hereinafter, the manufacturing process of the heat exchanger 1 will be described with reference to the manufacturing process diagrams of the heat exchanger 1 of FIGS. 2 (a), 2 (b) to 5 (a), (b), (c). Note that the heat exchanger 1 is illustrated by omitting a part of the fins 2a constituting the laminated fins 2 for easy understanding of the drawing.
First, as shown in FIGS. 2 (a) and 2 (b), a plurality of heat transfer tubes 4 are inserted into the corresponding insertion tubes 8 from the end 4a side, and the state shown in FIG. 3 (a) is obtained. (Insertion process). In this state, as shown in FIG. 3 (b), the outer peripheral surface 4 b of the heat transfer tube 4 and the inner peripheral surface 8 b of the insertion tube 8 are spaced apart with a gap G.

Next, as shown in FIGS. 4 (a) and 4 (b), a plurality of drill-like tube expansion jigs 16 are expanded by screwing them into the heat transfer tubes 4 from the end portions 4a side (first). 1 tube expansion).
Specifically, as shown in FIG. 4B, the outer peripheral surface 4b of the heat transfer tube 4 is pressed and brought into close contact with the inner peripheral surface 8b of the insertion tube 8, and the heat transfer tube 4 is inserted into the heat transfer tube 4 from the end 4a. 8 is expanded substantially uniformly to the extent that the gap G disappears over the portion facing 8, and the contact portion 10 is formed in the heat transfer tube 4. The heat transfer tube 4 is tightly fixed to the insertion tube 8 and eventually the laminated fin 2 by the formation of the close contact portion 10 (contact step).

The first expanded pipe is expanded at a relatively small expansion ratio of about 106%, and the decrease in the wall thickness t ₁ of the heat transfer tube 4 due to the first expanded tube is so small that it does not affect the pressure resistance of the heat transfer tube 4. Is. In the first tube expansion, the inner diameter D _IN1 of the heat transfer tube 4 is expanded tube to be substantially equal to the outer diameter D _OUT2 of the bent pipe 6, i.e., the end portion 4a of the bent pipe 6 is heat transfer tubes 4 after adhesion step The outer diameter D _OUT2 is formed in advance so that it can be inserted with an intermediate fit that is intermediate between the clearance fit and the fit fit (see FIG. 1).

Next, as shown in FIG. 5 (a), the respective bend pipes 6 are sequentially brazed and joined so as to connect the adjacent end portions 4a of different heat transfer pipes 4 (joining step).
Here, as shown in FIGS. 5 (b) and 5 (c), the heat transfer tube 4 has a gap G from the end portion 4a to the portion of the heat transfer tube 4 that faces the insertion tube 8 in the contact process. Since the pipes are expanded substantially uniformly, the joint portion 12 and the close contact portion 10 of the heat transfer tube 4 in the joining step have substantially the same inner diameter, in other words, the outer peripheral surface 12a of the joint portion 12 in the heat transfer tube 4 and The contact portion 10 is substantially flush with the outer peripheral surface 10a. In addition, since the bend pipe 6 is formed in advance at the outer diameter _DOUT2 that can be inserted into the end 4a with a fit of about an intermediate fit, the bend pipe 6 can be connected to the heat transfer pipe 4a without further expanding the end 4a. It is inserted as it is.

Also, a ring-shaped brazing member 18 is mounted in advance on the end portion 6a of the bend tube 6, and the brazing member 18 is provided at a position that defines an insertion distance d of the bend tube 6 into the heat transfer tube 4. That is, the insertion allowance d is managed according to the mounting position of the brazing member 18, and the brazing member 14, and thus the joining portion 12, is formed by melting the brazing member 18 in contact with the opening end surface of the end portion 4a. The tube 6 is fixed to the heat transfer tube 4 in an airtight manner.

Thus, through the insertion process, the adhesion process, and the bonding process as described above, a refrigerant communication path that is continuous in a bellows shape is formed in the heat exchanger 1, and the manufacturing process of the heat exchanger 1 is completed.
As described above, in the present embodiment, the outer peripheral surface 12a of the joint portion 12 is substantially flush with the outer peripheral surface 10a of the close-contact portion 10, and the end portion 4a of the heat transfer tube 4 does not need to be expanded. With the accompanying reduction in the thickness of the end 4a, the pressure resistance of the heat transfer tube 4 can be reduced, the heat transfer tube 4 can be prevented from rupturing due to the refrigerant pressure, and the pressure resistance of the heat exchanger 1 can be improved.

Specifically, in the prior art, generally, after the adhesion step, a tube expansion jig such as that used in the first tube expansion is screwed into only the end portion 4a of the heat transfer tube 4 to expand the end portion 4a. 2 Tube expansion is performed.
Here, in the joining step, a bend pipe 6 having substantially the same outer diameter as that of the heat transfer pipe 4 is inserted into the end portion 4a expanded by the second pipe expansion and brazed, so that the expansion ratio of the second expansion pipe is the above-mentioned first expansion ratio. becomes larger than the expansion ratio of the expanded pipe, than this very reduced wall thickness t ₁ of the end portion 4a of the heat transfer tube 4 due to the second tube expansion, pressure resistance of the heat transfer tube 4 is significantly decreased by thinning of the end 4a . Conventionally, a refrigerant pipe used for a refrigerant circuit of an air conditioner is often diverted to a heat pump circuit, and the outer diameter D _OUT1 of the heat transfer pipe 4 and the outer diameter D _OUT2 of the bend pipe 6 are both about 7 mm.

However, in this embodiment, since the junction part 12 can be formed in the heat exchanger tube 4 without performing a 2nd pipe expansion, the thickness reduction of the edge part 4a can be prevented and the pressure resistance strength of the heat exchanger tube 4 can be raised. .
In addition, since the outer diameter D _OUT1 of the heat transfer tube 4 and the outer diameter D _OUT2 of the bend tube 6 are both about 5 mm, there is an advantage that the weight of the heat exchanger 1 can be reduced.

Furthermore, the manufacturing process of the heat exchanger 1 mainly includes an adhesion process and a bonding process for forming the joint portion 12 having the outer circumferential surface 12a substantially flush with the outer circumferential surface 10a after the adhesion process. Thereby, since the 2nd pipe expansion process (tube expansion process) which expands the edge part 4a becomes unnecessary, and the number of processes in the manufacturing process of the heat exchanger 1 can be reduced, the manufacturing cost of the heat exchanger 1 is reduced. Can do.

The description of one embodiment of the present invention is finished above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the said embodiment, although the heat exchanger 1 is inserted in the heat pump circuit through which a carbon dioxide refrigerant circulates, and the carbon dioxide refrigerant distribute | circulates to the heat exchanger tube 4, a refrigerant | coolant is not limited to this. However, since the high pressure of the carbon dioxide refrigerant that is in a supercritical state acts on the heat transfer tube 4 by using the carbon dioxide refrigerant, the pressure resistance of the heat transfer tube 4 decreases due to the thinning of the end 4a of the heat transfer tube 4. Thus, the heat transfer tube 4 can be more effectively prevented from bursting.

Here, it is generally known that the pressure loss of the refrigerant greatly depends on the state of the refrigerant (ratio of gas / liquid) and the circulation flow rate of the refrigerant, and the pressure loss of the refrigerant increases as the circulation flow rate of the refrigerant increases. ing.
In addition, since carbon dioxide refrigerant has lower viscosity resistance than chlorofluorocarbon refrigerant, it is considered that pressure loss is small compared to chlorofluorocarbon refrigerant.

As shown in Fig. 6 (Source: CYPark, PSHrnjak / International Journal of Refrigeration 30 (2007) 166-178), the characteristic ratio of the refrigerant component ratio and the pressure loss with respect to the circulation flow rate, the carbon dioxide refrigerant is compared to the chlorofluorocarbon refrigerant. It can be seen that the pressure loss is actually 1/5 (20%) or more. Therefore, even when the outer diameter D _OUT2 of the bend pipe 6 is reduced from about 7 mm to about 5 mm, when carbon dioxide refrigerant is used as the refrigerant, the influence of the pressure loss of the refrigerant flowing through the heat exchanger 1 is Since it is considered that there is little, in the present invention, it is possible to effectively prevent the heat transfer tube 4 from bursting without worrying about an increase in the pressure loss of the refrigerant.

The outer peripheral surface of the joint portion of the bend tube in the heat transfer tube is substantially flush with the outer peripheral surface of the close contact portion of the heat transfer tube, so that the end portion of the heat transfer tube is not expanded, and the heat transfer tube accompanying the heat transfer is expanded It is possible to prevent the heat transfer tube from rupturing due to the reduced pressure resistance of the heat transfer tube due to the thinning of the end of the heat tube, and can be applied to applications that require an improvement in the pressure resistance of the heat exchanger. .

DESCRIPTION OF SYMBOLS 1 Heat exchanger 2 Laminated fin 4 Heat transfer tube 4a End part 6 Bend pipe 10 Contact | adherence part 10a Outer peripheral surface 12 Joining part 12a Outer peripheral surface

Claims

A heat exchanger in which the heat transfer tubes inserted through the laminated fins are connected by a bend tube,
The heat transfer tube is formed at an end portion of the heat transfer tube, which is in close contact with the stacked fin after being inserted into the multilayer fin, and a joint portion where the bend tube is inserted and brazed. And
The heat exchanger according to claim 1, wherein an outer peripheral surface of the joint portion is substantially flush with an outer peripheral surface of the contact portion.
The heat exchanger according to claim 1, wherein a carbon dioxide refrigerant is circulated through the heat transfer tube.
A heat exchanger manufacturing method for connecting heat transfer tubes inserted through laminated fins with a bend tube,
An adhesion process in which the heat transfer tube is inserted into the laminated fin and then closely adhered to the laminated fin to form an adhesion portion on the heat transfer tube;
After the contact step, the bend tube is inserted into the end portion of the heat transfer tube and brazed and joined to form a joint portion having an outer peripheral surface substantially flush with the outer peripheral surface of the close contact portion at the end portion. The manufacturing method of the heat exchanger characterized by consisting of a process.