WO2010032415A1

WO2010032415A1 - Refrigerant heating apparatus manufacturing method

Info

Publication number: WO2010032415A1
Application number: PCT/JP2009/004556
Authority: WO
Inventors: 若嶋真博; 下田順一
Original assignee: ダイキン工業株式会社
Priority date: 2008-09-17
Filing date: 2009-09-14
Publication date: 2010-03-25
Also published as: JP2011247429A

Abstract

Disclosed is a refrigerant heating apparatus manufacturing method that makes it possible to improve heat transfer from an outer tube to an inner tube. Said manufacturing method equips a refrigerant heating apparatus (30) with an inner tube (31) through which refrigerant flows, an outer tube (32), and an induction heating coil (33). The outer tube (32) is wrapped around the circumference of the inner tube (31) and made from a magnetic material. The induction heating coil (33) is wrapped around the circumference of the outer tube (32) and inductively heats the outer tube (32). This manufacturing method comprises an insertion step and a tube expansion step. In the insertion step, the inner tube (31), the outside diameter of which is smaller than the inside diameter of the outer tube (32), is inserted into the outer tube (32). In the tube expansion step, after the insertion step, the inner tube (31) is expanded so that the outer circumferential surface of the inner tube (31) is tightly compacted against the inner circumferential surface of the outer tube (32).

Description

Method for manufacturing refrigerant heating device

The present invention relates to a method for manufacturing a refrigerant heating device that heats a refrigerant flowing through a refrigerant pipe.

Conventionally, there are various methods for heating the refrigerant in the refrigerant circuit, but an induction heater (hereinafter referred to as IH heater) is convenient in that the refrigerant can be rapidly heated using induction heating.
Such an IH heater for heating a refrigerant can induce induction heating by exciting a pipe through which the refrigerant flows or a magnetic material inside and outside the pipe by an induction heating coil, thereby heating the refrigerant in the pipe. It is.

Here, copper is usually adopted as the material of the piping constituting the refrigerant circuit in consideration of aspects such as thermal conductivity, workability, or material cost. However, as the material of the pipe heated by the IH heater, it is preferable to employ a magnetic material such as stainless steel in order to efficiently perform electromagnetic induction heating.
Therefore, like the IH heater described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-174054), magnetic coating or powder is coated on the outer periphery of the copper tube so that induction heating can be efficiently performed even for the copper tube. I have to.

Here, in order to further improve the efficiency of induction heating, it is conceivable to employ a stainless steel pipe as a pipe through which the refrigerant flows inside the IH heater. In this case, the stainless steel pipe heated by the IH heater and other refrigerant circuits are considered. Since the material is different from that of the copper pipe constituting the wire, it is necessary to braze different pipes, and there is a possibility that defects (such as cracks) occur in the manufacturing cost and the brazed part.
It is also possible to insert a copper tube inside the stainless steel tube to make a double tube, but even if a copper tube having the same outer diameter is inserted into the inner diameter of the stainless steel tube, the stainless steel tube and the copper tube are good. There is a problem that it is difficult to obtain a proper contact state. For this reason, it is also difficult to improve the heat transfer from the stainless steel tube heated by induction to the copper tube.
The subject of this invention is providing the manufacturing method of the refrigerant | coolant heating apparatus which can improve the heat transfer from an outer tube | pipe to an inner tube | pipe.

The method for manufacturing a refrigerant heating device of the first invention is a method for manufacturing a refrigerant heating device including an inner tube through which a refrigerant flows, an outer tube, and an induction heating coil. The outer tube surrounds the inner tube and is made of a magnetic material. The induction heating coil surrounds the periphery of the outer tube and induction-heats the outer tube. This manufacturing method includes an insertion step and a tube expansion step. In the insertion step, an inner tube having an outer diameter smaller than the inner diameter of the outer tube is inserted into the outer tube. In the tube expanding step, after the inserting step, the inner tube is expanded to bring the outer peripheral surface of the inner tube into close contact with the inner peripheral surface of the outer tube.
Here, after the inner tube is inserted into the outer tube, the inner tube is expanded and the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube are brought into close contact with each other, so that the adhesion between the inner tube and the outer tube is improved. Further, the expansion of the inner tube can prevent the outer tube and the induction heating coil from falling. Moreover, it is easy to manufacture.

The manufacturing method of the refrigerant heating device of the second invention is the manufacturing method of the first invention, wherein the outer peripheral surface of the inner tube is provided with positioning means that protrudes outward of the inner tube. In the insertion step, the inner tube is arranged at a predetermined position inside the outer tube by bringing the positioning means into contact with the outer tube.
Here, in the insertion step, the positioning means is brought into contact with the outer tube to place the inner tube at a predetermined position inside the outer tube, so that the positioning of the inner tube within the outer tube is accurately performed by the positioning means. Is possible.

The manufacturing method of the refrigerant heating device of the third invention is the manufacturing method of the first invention or the second invention, wherein irregularities are formed on the outer peripheral surface of the inner tube and / or the inner peripheral surface of the outer tube. In the tube expanding step, the inner tube is expanded so that the unevenness is filled without any gaps, and the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube are brought into close contact with each other.
Here, in the tube expanding step, the inner tube is expanded so that the irregularities formed on the outer peripheral surface of the inner tube and / or the inner peripheral surface of the outer tube are filled without any gaps, and the outer peripheral surface of the inner tube and the inner periphery of the outer tube. Since the surfaces are brought into close contact with each other, the contact area between the inner tube and the outer tube is increased by the unevenness, and the adhesion is improved. As a result, heat transfer from the outer tube to the inner tube, which is heated by induction, and thus heat transfer to the refrigerant is improved.

The manufacturing method of the refrigerant heating device of the fourth invention is the manufacturing method of the first invention, wherein the inner tube is made of copper.
Here, since the inner tube is made of copper, it has good thermal conductivity and is easy to expand.

The manufacturing method of the refrigerant heating apparatus of the 5th invention is a manufacturing method of the refrigerant heating apparatus of the 1st invention, Comprising: The outer tube is manufactured with stainless steel.
Here, since the outer tube is made of stainless steel, induction heating can be performed efficiently, and the inner tube surface is uneven because the outer tube is harder than the inner tube such as copper having good thermal conductivity. Easy to adhere to.

The manufacturing method of the refrigerant heating device of the sixth invention is the manufacturing method of the refrigerant heating device of the third invention, wherein the irregularities are formed on either the outer peripheral surface of the inner tube or the inner peripheral surface of the outer tube. And a protrusion formed on the other side. The groove and the ridge extend in a spiral shape.
Here, since the spirally extending grooves and ridges are formed on the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube, the contact area between both the tubes increases, and the induction tube is heated from the outer tube to the inner tube. Heat transfer, and thus heat transfer to the refrigerant.

According to the first invention, the adhesion between the inner tube and the outer tube is improved. Moreover, the outer tube and the induction heating coil can be prevented from falling. Moreover, it is easy to manufacture.
According to the second aspect of the invention, the positioning of the inner tube within the outer tube can be accurately performed by the positioning means.
According to the third aspect of the invention, the contact area between the inner tube and the outer tube is increased by the unevenness, and the adhesion is improved. As a result, heat transfer from the outer tube to the inner tube, which is heated by induction, and thus heat transfer to the refrigerant is improved.
According to the fourth aspect of the invention, the thermal conductivity is good and the tube is easy to expand.
According to the fifth aspect of the invention, induction heating can be performed efficiently and is harder than the inner tube made of copper or the like having good thermal conductivity, so that the irregularities on the inner peripheral surface of the outer tube are easily adhered to the inner tube surface.
According to the sixth aspect of the invention, the contact area between the inner tube and the outer tube is increased, and the heat transfer from the outer tube to the inner tube that is induction-heated, and thus the heat transfer to the refrigerant is improved. Moreover, compared with the case where a point-shaped convex part, a recessed part, etc. are formed, the direction of a groove | channel or a protrusion can ensure sufficient contact area. Moreover, since the grooves and ridges extend spirally, the contact area is further increased compared to the linear grooves and ridges, so heat transfer from the outer tube to the inner tube that is induction-heated, As a result, the heat transfer performance of heat transfer to the refrigerant is further improved.

The circuit diagram of the air conditioner to which the IH heater assembly concerning the embodiment of the present invention was attached. The expansion perspective view of the machine room part of the outdoor unit of FIG. FIG. 2 is a front view of the IH heater assembly of FIG. 1. FIG. 2 is a cross-sectional view of the IH heater assembly of FIG. 1. Cross-sectional explanatory drawing which shows the insertion process in the manufacturing method of the IH heater assembly of FIG. Cross-sectional explanatory drawing which shows the pipe expansion process in the manufacturing method of the IH heater assembly of FIG. Sectional explanatory drawing which shows the bobbin mounting process in the manufacturing method of the IH heater assembly of FIG. FIG. 2 is an enlarged perspective view showing linear grooves and ridges formed on a contact surface between an inner tube and an outer tube in FIG. 1. The perspective enlarged view which shows the helical groove | channel and protrusion which were formed in the contact surface of the inner tube and outer tube concerning the modification of this invention.

Next, an embodiment of a method for manufacturing a refrigerant heating device of the present invention will be described with reference to the drawings.
Embodiment
<Basic configuration of the air conditioner 1>
In the air conditioner 1 including the refrigerant heating device 30 (hereinafter referred to as the IH heater assembly 30) shown in FIG. 1, the outdoor unit 2 and the indoor unit 4 are connected to the liquid refrigerant communication pipe 6 and the gas refrigerant as shown in FIG. A refrigerant circuit 11 configured to be connected by a communication pipe 7 is provided. Each refrigerant pipe of the refrigerant circuit 11 is usually made of copper.
As shown in FIGS. 1 and 2, the refrigerant circuit 11 includes, in the outdoor unit 2, a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23, an expansion valve 24 including an electronic expansion valve with adjustable throttle, An IH heater assembly 30 and an accumulator 25 are provided. In addition, the refrigerant circuit 11 includes an indoor heat exchanger 26 and the like inside the indoor unit 4 as shown in FIG. In addition, the four-way selector valve 22 has shown the switching connection state in the case of performing heating operation in FIG.

Here, the refrigerant flowing in the refrigerant circuit 11 is not particularly limited in the present invention, and is, for example, HFC (R410A or the like), carbon dioxide refrigerant, or the like.
As shown in FIG. 1, the refrigerant circuit 11 includes a discharge pipe A, an indoor gas pipe B, an indoor liquid pipe C, an outdoor liquid pipe D, an outdoor gas pipe E, an accumulator pipe F, and a suction pipe G. ing.
Hereinafter, the connection state of each refrigerant pipe will be described in the order of the flow path where the refrigerant discharged from the compressor 21 flows out and is sucked into the compressor 21 again.
The discharge pipe A connects the discharge side of the compressor 21 and the four-way switching valve 22.
The indoor side gas pipe B connects the four-way switching valve 22 and the gas side of the indoor heat exchanger 26.
The indoor side liquid pipe C connects the liquid side of the indoor heat exchanger 26 and the expansion valve 24. Here, the indoor side liquid pipe C includes a liquid communication pipe 6 that connects the outdoor unit 2 and the indoor unit 4.

The outdoor liquid pipe D connects the expansion valve 24 and the liquid side of the outdoor heat exchanger 23.
The outdoor gas pipe E connects the gas side of the outdoor heat exchanger 23 and the four-way switching valve 22.
The accumulator pipe F connects the four-way switching valve 22 and the accumulator 25.
The suction pipe G connects the accumulator 25 and the suction side of the compressor 21.
In this way, the refrigerant circuit 11 is configured, and heating operation can be performed by circulating the refrigerant in the above-described direction. The cooling operation can also be performed by switching the connection state of the four-way switching valve 22.
In the middle of the accumulator tube F, an IH heater assembly 30 described later is connected by brazing.

<Configuration of IH heater assembly 30>
As shown in FIGS. 3 and 4, the IH heater assembly 30 is an IH heater composed of a double tube, and includes an inner tube 31, an outer tube 32, an induction heating coil 33, a bobbin 34, and a pair of lids. 35, a pair of nuts 36, a plurality of ferrite blocks 37, a ferrite holder 38, and a sheet metal cover 39.

The inner pipe 31 is made of copper, which is the same material as the refrigerant pipe 5, and the refrigerant flows through the inner pipe 31.
A positioning rib 42 is provided on the outer peripheral surface 45 of the inner tube 31 so as to protrude outward from the inner tube 31. The positioning rib 42 contacts the opening edge 32b of the outer tube 32 when the inner tube 31 is inserted into the outer tube 32 when the IH heater assembly 30 is manufactured. Position to.
The positioning rib 42 is one aspect of the positioning means of the present invention, and may be any protrusion that protrudes outward of the inner tube 31 and can hit the opening edge 32b of the outer tube 32. It is formed by expanding a part of the inner tube 31 outward.
The outer tube 32 is made of stainless steel, which is a magnetic material, and is disposed around the inner tube 31. Specifically, by expanding the inner tube 31, the outer peripheral surface of the inner tube 31 and the inner peripheral surface of the outer tube are in close contact with each other. The positioning means of the present invention may be a band-shaped member such as a tie wrap or a rubber band.

As shown in FIG. 8, a plurality of linear grooves 44 are formed at equal intervals along the inner peripheral surface 43 on the inner peripheral surface 43 of the outer tube 32. On the other hand, linear protrusions 46 are formed on the outer peripheral surface 45 of the inner tube 31 so as to fit into the grooves 44 of the outer tube 32, respectively.
As will be described later, when the inner tube 31 is expanded, the protrusion 46 is pressed against the inner peripheral surface 43 of the outer tube 32 in which the groove 44 is formed in the inner peripheral surface 43 in advance. Formed on surface 45. Since the copper inner tube 31 is softer than the stainless steel outer tube 32, the protrusion 46 can be easily and reliably formed on the outer peripheral surface of the inner tube 31.
Thus, the area where the outer peripheral surface 45 of the inner tube 31 and the inner peripheral surface 43 of the outer tube 32 are in contact with each other by the groove 44 formed inside the outer tube 32 and the protrusion 46 formed outside the inner tube 31. Is expanding.

The induction heating coil 33 surrounds the outer tube 32 and induction-heats the outer tube 32. The induction heating coil 33 is arranged so as to surround the outer periphery of the outer tube 32 in a state of being wound around a bobbin 34 which is a separate member from the outer tube 32.
The bobbin 34 is a cylindrical member whose both ends are open, and the induction heating coil 33 is wound around the side peripheral surface thereof.
The pair of lids 35 has an opening 35 a at the center and is fitted to the outer periphery of the outer tube 32. In addition, the pair of lids 35 is fixed from both the upper and lower sides by a C-shaped ferrite holder 38 to be described later while being attached to the bobbin 34.
The pair of nuts 36 is a combination of the bobbin 34, the lid 35, the ferrite holder 38, and the nut 36 of the IH heater assembly 30 in advance by being screwed into male screw portions 32a formed on the outer periphery near both ends of the outer tube 32. Is fixed to the outer periphery of the outer tube 32.

The plurality of ferrite blocks 37 are mounted side by side on a C-shaped ferrite holder 38 in order to reduce leakage magnetic flux to the outside of the sheet metal cover 39 of the IH heater assembly 30. The ferrite holder 38 is attached from the outside of the induction heating coil 33 from the four sides of the bobbin 34.
As shown in FIGS. 2 and 4, the sheet metal cover 39 is a cover made of a thin metal plate and is screwed to the outside of the ferrite holder 38. The sheet metal cover 39 has a cylindrical shape or a polygonal shape so as to surround the cylindrical bobbin 34, and has an integrated shape or a shape divided into two or more.
Thereby, since the inner pipe 31 is made of the same kind of copper as the other refrigerant pipes F, the inner pipe 31 and the refrigerant pipe F can be easily joined (manufactured easily). Moreover, efficient induction heating is possible by the outer tube 32 made of a magnetic material such as stainless steel.

The material of the outer tube 32 covering the periphery of the copper inner tube 31 is not limited to stainless steel, and for example, at least 2 selected from conductors such as iron, copper, aluminum, chromium, nickel, and the like. An alloy containing more than one kind of metal can be used. Examples of stainless steel include at least one of ferrite and martensite, or a combination thereof.
Moreover, since the structure which supports the bobbin 34 with the induction heating coil 33 wound around the thick outer tube 32 is adopted, the overall strength of the IH heater assembly 30 is improved.
As described above, the IH heater assembly 30 is provided in the middle of the portion of the accumulator pipe F that connects the four-way switching valve 22 and the accumulator 25, so that as shown in FIG. By the IH heater assembly 30 that receives the high-frequency alternating current from the high-frequency power source 60 via the intake air, the intake gas refrigerant that is directed from the four-way switching valve 22 to the accumulator 25 can be warmed, and the heating capacity can be improved.

In addition, when the heating operation is started, the compressor 21 may not be sufficiently warmed. Here, the IH heater assembly 30 generates heat, so that the gas from the four-way switching valve 22 toward the accumulator 25 is generated. The refrigerant can be heated, and the lack of capacity at the start-up can be compensated.
Further, when the four-way switching valve 22 is switched to the state for cooling operation and the defrost operation for removing the frost attached to the outdoor heat exchanger 23 is performed, the gas refrigerant heated through the IH heater assembly 30 is used. Can be further compressed by the compressor 21, so that the temperature of the hot gas discharged from the compressor 21 can be increased. Thereby, the time required to thaw frost by defrost operation can be shortened. Thereby, even if it is necessary to perform a defrost operation in a timely manner during the heating operation, the operation can be returned to the heating operation as soon as possible, and the user's comfort can be improved.

<Method for Manufacturing IH Heater Assembly 30>
When manufacturing the IH heater assembly 30 of the present embodiment, first, as shown in FIG. 5, the inner tube 31 having an outer diameter smaller than the inner diameter of the outer tube 32 is inserted into the outer tube 32. Specifically, the copper inner pipe 31 constituting a part of the refrigerant pipe of the refrigerant circuit 11 is inserted into the stainless steel outer pipe 32 made of a magnetic material (insertion step).

In this insertion step, the inner tube 31 can be disposed at a predetermined position inside the outer tube 32 by bringing the positioning rib 42 protruding outward from the inner tube 31 into contact with the opening edge 32b of the outer tube 32. is there.
Then, after the insertion step, the inner tube 31 is expanded to bring the outer peripheral surface 45 of the inner tube 31 and the inner peripheral surface 43 of the outer tube 32 into close contact. Specifically, as shown in FIG. 6, by pressing-in a tube expansion billet 41 having an outer diameter that is slightly larger than the inner diameter of the inner tube 31, the inner tube 31 moves in a direction in which the outer diameter increases. By being enlarged, it fits inside the outer pipe 32 (pipe expansion process). At this time, when the inner tube 31 is expanded, the inner tube 31 is expanded so that the unevenness is filled without any gaps by being pressed against the inner peripheral surface 43 of the outer tube 32 in which the groove 44 is formed in the inner peripheral surface 43 in advance. Thus, the outer peripheral surface 45 of the inner tube 31 and the inner peripheral surface 43 of the outer tube 32 are brought into close contact with each other. As a result, the protrusion 46 is formed on the outer peripheral surface 45 of the inner tube 31.

Thereafter, as shown in FIG. 7, a combination of the bobbin 34, the lid 35, the ferrite holder 38 and the nut 36 of the IH heater assembly 30 in advance is inserted into the outer periphery of the outer tube 32 with the nut 36 loosened, After that, the nut 36 is fastened to the outer tube 32 and is pressed against the C-shaped ring 43 in the inner diameter direction, whereby the bobbin 34 and other main parts are mounted (bobbin mounting step). Thereby, the manufacture of the IH heater assembly 30 is completed.

<Features of the embodiment>
(1)
The manufacturing method of the IH heater assembly 30 according to the embodiment includes an insertion step of inserting the inner tube 31 having an outer diameter smaller than the inner diameter of the outer tube 32 into the outer tube 32, and then expanding the inner tube 31 to expand the inner tube. 31 includes a tube expansion step for bringing the outer peripheral surface 45 of the outer tube 31 and the inner peripheral surface 43 of the outer tube 32 into close contact with each other. Heat transfer to the inner pipe 31 and thus heat transfer to the refrigerant is improved.

Further, by expanding the inner tube 31, the components of the IH heater assembly 30 other than the inner tube 31 (that is, the outer tube 32 and the induction heating coil 33, other bobbins 34, a pair of lids 35, a pair of nuts 36, a plurality of ferrites) The block 37, the ferrite holder 38, and the sheet metal cover 39) can be prevented from falling.
In addition, since the adhesion with the outer tube 32 is improved simply by expanding the inner tube 31, the IH heater assembly 30 can be easily manufactured.
(2)
In the manufacturing method of the IH heater assembly 30 according to the embodiment, the outer peripheral surface 45 of the inner tube 31 is provided with positioning ribs 42 that protrude outward from the inner tube 31. Since the inner tube 31 is arranged at a predetermined position inside the outer tube 32 by contacting the tube 32, the inner tube 31 can be easily and accurately positioned inside the outer tube 32.
(3)
In the manufacturing method of the IH heater assembly 30 according to the embodiment, the outer peripheral surface 45 of the inner tube 31 and / or the inner peripheral surface 43 of the outer tube 32 are formed with irregularities such as grooves 44 and ridges 46, The inner tube 31 is expanded so that the unevenness is filled without a gap, and the outer peripheral surface 45 of the inner tube 31 and the inner peripheral surface 43 of the outer tube 32 are brought into close contact with each other. The unevenness increases the contact area between the inner tube 31 and the outer tube 32 and improves the adhesion. As a result, heat transfer from the outer tube 32 to the inner tube 31 that is induction-heated, and thus heat transfer to the refrigerant is improved.
(4)
In the manufacturing method of the IH heater assembly 30 of the embodiment, since the inner pipe 31 is made of copper, it has good thermal conductivity and is easy to expand.
(5)
In the method of manufacturing the IH heater assembly 30 according to the embodiment, the outer tube 32 is made of stainless steel, so that induction heating is performed more efficiently than a tube made of other magnetic material, such as an iron tube. In addition, it has advantages such as high strength and long life.

<Modification>
(A)
In the above-described embodiment, as shown in FIG. 8, linear grooves 44 and ridges 46 are respectively formed on the contact surfaces of the inner tube 31 and the outer tube 32 as an example of unevenness. However, the present invention is not limited to this, and other uneven forms, for example, spiral grooves and protrusions, or combinations of scattered protrusions and depressions may be used.
(B)
For example, as shown in FIG. 9, the grooves 47 and the protrusions 48 may extend spirally. In this case, the contact area between the inner tube 31 and the outer tube 32 is increased, and heat transfer from the outer tube 32 that is induction-heated to the inner tube 31, and hence heat transfer to the refrigerant, is improved. Moreover, in the case of the spiral groove 47 and the ridge 48 shown in FIG. 9, the length is longer than that of the linear groove 44 and the ridge 46 shown in FIG. The contact area between the outer tube 32 and the outer tube 32 is increased, and heat transfer performance is improved.

When the inner tube 31 is expanded, the spiral protrusion 48 is pressed against the inner peripheral surface 43 of the outer tube 32 in which the spiral groove 47 is formed in the inner peripheral surface 43 in advance. It is formed on the outer peripheral surface 45 of the tube 31.

The present invention can be variously applied to the field of manufacturing methods of refrigerant heating devices.

DESCRIPTION OF SYMBOLS 1 Air conditioner 2 Outdoor unit 4 Indoor unit 6 Liquid refrigerant communication piping 7 Gas refrigerant communication piping 11 Refrigerant circuit 21 Compressor 22 Four-way switching valve 23 Outdoor heat exchanger 24 Expansion valve 25 Accumulator 26 Indoor heat exchanger 30 IH heater assembly (Refrigerant heating device)
31 Inner tube 32 Outer tube 33 Induction heating coil 34 Bobbin 35 Lid 36 Nut 37 Ferrite block 38 Ferrite holder 39 Sheet metal cover 41 Expanded billet 42 Positioning rib (positioning means)
43 (outer tube 32) inner peripheral surface 44 (linear) groove 45 (inner tube 31) outer peripheral surface 46 ridge 47 (spiral) groove 48 (spiral) ridge A discharge tube B indoor side Gas pipe C indoor side liquid pipe D outdoor side liquid pipe E outdoor side gas pipe F accumulator pipe G suction pipe

Japanese Patent Laid-Open No. 2001-174054

Claims

An inner pipe (31) through which the refrigerant flows;
Surrounding the inner pipe (31), and an outer pipe (32) made of a magnetic material;
A method of manufacturing a refrigerant heating device (30) including an induction heating coil (33) surrounding the outer tube (32) and induction heating the outer tube (32),
An insertion step of inserting the inner tube (31) having an outer diameter smaller than the inner diameter of the outer tube (32) into the outer tube (32);
After the inserting step, the refrigerant heating device (30) includes a tube expanding step of expanding the inner tube (31) and bringing the outer peripheral surface of the inner tube (31) into close contact with the inner peripheral surface of the outer tube (32). ) Manufacturing method.
Positioning means (42) projecting outward of the inner pipe (31) is provided on the outer peripheral surface of the inner pipe (31),
In the insertion step, the inner pipe (31) is disposed at a predetermined position inside the outer pipe (32) by bringing the positioning means (42) into contact with the outer pipe (32).
The manufacturing method of the refrigerant | coolant heating apparatus (30) of Claim 1.
Concavities and convexities are formed on the outer peripheral surface of the inner tube (31) and / or the inner peripheral surface of the outer tube (32),
In the tube expanding step, the inner tube (31) is expanded so that the unevenness (44, 46, 47, 48) is filled without a gap, and the outer peripheral surface of the inner tube (31) and the outer tube (32) are expanded. Close contact with the inner surface,
The manufacturing method of the refrigerant | coolant heating apparatus (30) of Claim 1 or 2.
The inner pipe (31) is made of copper,
The manufacturing method of the refrigerant | coolant heating apparatus (30) of Claim 1.
The outer tube (32) is made of stainless steel,
The manufacturing method of the refrigerant | coolant heating apparatus (30) of Claim 1.
The irregularities (47, 48) are formed on the groove (47) formed on one of the outer peripheral surface of the inner tube (31) and the inner peripheral surface of the outer tube (32) and on the other. Consists of ridges (48),
The groove (47) and the ridge (48) extend spirally,
The manufacturing method of the refrigerant | coolant heating apparatus (30) of Claim 3.