WO2017038962A1

WO2017038962A1 - Method for manufacturing double pipe

Info

Publication number: WO2017038962A1
Application number: PCT/JP2016/075757
Authority: WO
Inventors: 飯島　健次; 林　直人
Original assignee: 株式会社ヴァレオジャパン
Priority date: 2015-09-04
Filing date: 2016-09-02
Publication date: 2017-03-09
Also published as: JP2016053469A

Abstract

To provide a method for manufacturing a double pipe where it is possible to easily insert an inner pipe into an outer pipe, and to easily and reliably secure the outer pipe and the inner pipe irrespective of the extension-direction dimensions of straight parts or curved parts. The steps for manufacturing a double pipe (7) used as an internal heat exchanger in a refrigeration cycle mounted in a vehicle comprise an insertion step for inserting an inner pipe (11) having a smaller outer diameter than the inner diameter of an outer pipe (12) into the outer pipe (12), and a securing step for securing the outer pipe (12) and the inner pipe (11) by indenting a portion of the outer pipe (12) until contact is made with the outer circumference of the inner pipe (11), said securing step being performed after the insertion step. In the securing step, e.g., the outer pipe (12) is indented so as to have a plurality of bottomed holes (22) present therein in various locations.

Description

Manufacturing method of double pipe

The present invention relates to a method for easily manufacturing a double pipe used as an internal heat exchanger of a refrigeration cycle mounted on a vehicle.

In order to improve the refrigeration efficiency of the refrigeration cycle, for example, a double pipe disclosed in Patent Document 1, Patent Document 2, etc. is used as an internal heat exchanger for exchanging heat between the medium on the high pressure side and the medium on the low pressure side. Is known.

These double pipes disclosed in Patent Document 1 and Patent Document 2 include a first medium that includes an outer pipe and an inner pipe inserted into the outer pipe, and flows between the outer pipe and the inner pipe. And a heat exchange between the second medium flowing through the inner pipe.

Thus, since the double pipe has a gap through which the first medium flows between the outer pipe and the inner pipe, when the vibration of the vehicle is transmitted to the double pipe, the outer pipe and the inner pipe May vibrate and the outer tube and the inner tube come into contact with each other, generating abnormal noise and damaging the outer tube and the inner tube.

Therefore, in Patent Document 1, the double pipe is configured to have a straight pipe part and bent parts arranged on both sides of the straight pipe part. In the straight pipe part, the outer surface (outer circumference) of the inner pipe does not contact the inner surface (inner circumference) of the outer pipe, or the outer surface of the inner pipe contacts only one of the inner surfaces of the outer pipe, while in the bent part, the outer surface of the inner pipe And the inner surface of the outer tube are in contact in a plurality of radial directions. By adopting such a double pipe configuration, the outer pipe and the inner pipe are fixed, and even if vibration is transmitted to the double pipe, generation of abnormal noise and damage to the inner pipe and outer pipe are prevented. It can be done.

In addition, the double pipe disclosed in Patent Document 2 is provided with a spiral concavo-convex part in the straight pipe part of the inner pipe, and the convex part of the convex concave part is the inner surface of the outer pipe. It is the structure which contact | abutted.

JP 2006-162241 A JP 2013-113525 A

However, in the structure and manufacturing method of the double pipe disclosed in Patent Document 1, when vibration is transmitted to the double pipe, generation of abnormal noise due to contact of the inner pipe and the outer pipe, and the inner pipe and the outer pipe It is difficult to reliably prevent damage to the

An outline of the manufacturing method of the double pipe of Patent Document 1 will be described. An insertion process for inserting an inner pipe formed with a spiral groove into an outer pipe is performed, and then a bending process for bending the inner pipe and the outer pipe at the same time is performed. The bent portion is formed by performing the operation, and the inner tube is brought into contact with the outer tube at a plurality of positions only at the formed bent portion.

By configuring the bending portion in this way, the outer tube and the inner tube are fixed in the bending portion, but the outer tube and the inner tube are not fixed in the vicinity of the bending portion in the straight tube portion. In other words, the inner surface of the outer tube and the outer surface of the inner tube are close to each other, and there is a risk of contact when vibration is transmitted to the double tube. Also, if the distance between one bent part and the other bent part is long (the dimension of the straight pipe part is long in the extending direction of the pipe), when vibration is transmitted to the double pipe, the outer pipe and the inner pipe May be bent, and the inner surface of the outer tube may come into contact with the outer surface of the inner tube. In the first place, if two bent portions are always provided as in Patent Document 1, the degree of freedom in design of the double pipe is significantly limited.

In this regard, the double pipe disclosed in Patent Document 2 is inserted into the outer pipe so that the convex part of the inner pipe in which the spiral convex concave part is formed is in contact with the inner surface of the outer pipe that is a straight pipe. Therefore, it is foreseen that when the vibration from the vehicle is transmitted, the generation of noise in the straight pipe portion and the damage of the inner pipe and the outer pipe are prevented. However, the outer tube and the inner tube are not fixed at the bent portion, and the outer tube and the inner tube may be bent, and the inner surface of the outer tube and the outer surface of the inner tube may come into contact with each other. In particular, the larger the bend R of the bent portion, the higher the risk of contact. In addition, regarding the straight pipe portion to which the inner pipe and the outer pipe are fixed, in Patent Document 2, how to fix the inner pipe in which the spiral convex and concave portions are formed in advance to the inner surface of the outer pipe is two. The fixing process of the manufacturing method of a heavy pipe is not disclosed.

Accordingly, an object of the present invention is to provide a method of manufacturing a double tube that can fix an outer tube and an inner tube regardless of the presence or absence of a bending portion and can easily manufacture a double tube having high vibration resistance. Yes.

A manufacturing method of a double pipe according to the present invention is a manufacturing method of a double pipe used as an internal heat exchanger of a refrigeration cycle mounted on a vehicle, and the outer pipe has an outer diameter that is larger than the inner diameter of the outer pipe. An insertion step of inserting a small inner tube, and a step performed after the insertion step, in which a part of the outer tube is recessed until it comes into contact with the outer periphery of the inner tube, and the outer tube and the inner tube are And a fixing step for fixing. (Claim 1) As will be described below, the medium that flows between the inner tube and the outer tube is the first medium, and the medium that flows in the inner tube is the second medium. These media are, for example, refrigerants.

As a result, a step of inserting an inner tube having an outer diameter smaller than the inner diameter of the outer tube into the outer tube, and a part of the outer tube with the inner tube inserted therein are recessed, and Since the outer tube and the inner tube are fixed by the step of contacting the tube, the outer tube and the inner tube can be easily fixed regardless of the presence or absence of the bent portion.

In the method for manufacturing a double pipe according to the invention described in claim 2, the fixing step is a step of denting the outer pipe along the extending direction of the outer pipe.

Thereby, since the outer tube is recessed from a certain direction, the step of rotating the outer tube or the jig becomes unnecessary, and thus the double tube can be easily manufactured.

In the double pipe manufacturing method according to the invention of claim 3, the fixing step is a step of denting the outer pipe so that a plurality of bottomed holes are scattered.

This allows the outer tube to be recessed at an arbitrary position, so that the productivity of the double tube can be improved and the design freedom of the recess can be improved.

In the method for manufacturing a double tube according to the invention described in claim 4, the fixing step is a step of recessing the outer tube in a spiral shape. The number of spiral dents may be one or two or more.

As a result, the first medium flowing between the outer tube and the inner tube is caused to flow spirally using the spiral recess formed in the outer tube as a guide, and the second medium flows through the inner tube. A double tube with improved heat exchange rate with the medium can be provided by an easy manufacturing method.

In the method of manufacturing a double pipe according to the invention described in claim 5, when the fixing step causes the outer pipe to be helically recessed, the top surface of the portion of the outer pipe that is helically recessed is It is a process of continuously contacting the inner pipe.

As a result, the top surface of the spirally recessed portion of the outer tube continuously contacts the inner tube, so that the first medium flowing between the outer tube and the inner tube is an extension of the double tube. Since a short circuit in the direction is prevented and the spiral flow is ensured, the heat exchange rate with the second medium flowing through the inner tube can be easily improved.

In the method for manufacturing a double pipe according to the invention described in claim 6, the inner pipe has a recess whose outer periphery is recessed spirally.

As a result, the first medium flowing between the outer tube and the inner tube is spirally passed through the inner tube through the inner tube, with the outer periphery of the inner tube serving as a guide. A double tube with an improved heat exchange rate with the second medium can be provided by an easy manufacturing method.

In the method of manufacturing a double pipe according to the invention of claim 7, as the process performed between the insertion process and the fixing process, the outer pipe in which the inner pipe is inserted is bent to a predetermined angle, or A bending process for bending is provided, and the fixing step is performed on a portion of the outer tube that is bent or bent by the bending process.

Thereby, even after the outer tube into which the inner tube is inserted is bent or bent by bending, the outer tube and the inner tube can be easily fixed at the bent or bent portion. it can.

In the method of manufacturing a double pipe according to the invention described in claim 8, the fixing step causes the part of the outer pipe to be recessed until a part of the outer pipe reaches the inner side of the outer periphery of the inner pipe. It is a process.

Thereby, when a part of the outer tube is recessed as a fixing step, the outer tube and the inner tube are fitted by being recessed until a part of the outer tube reaches the inner side of the outer periphery of the inner tube. The outer tube and the inner tube can be easily and firmly fixed.

In the method for manufacturing a double pipe according to the invention described in claim 9, the outer pipe and the inner pipe are made of aluminum. Thereby, since plastic deformation of a pipe can be performed comparatively easily, it is suitable for manufacture of a double pipe.

As described above, according to the present invention, the step of inserting an inner tube having an outer diameter smaller than the inner diameter of the outer tube into the outer tube, and a part of the outer tube with the inner tube inserted therein The outer tube and the inner tube are fixed by the step of making the dent and the inner tube are brought into contact with the inner tube, so that the outer tube and the inner tube can be easily fixed regardless of the presence or absence of the bent portion. be able to.

FIG. 1 is a schematic view of a refrigeration cycle provided with a double pipe as an internal heat exchanger. 2A and 2B are explanatory views showing an outline of the double tube in Example 1. FIG. 2A is a perspective view of the double tube, and FIG. 2B is a cross-sectional view of the double tube. . 3A is an enlarged view of the cross-sectional view taken along the line AA in FIG. 2B, and FIG. 3B is an enlarged view of the cross-sectional view taken along the line BB of FIG. 2B. 4A and 4B are explanatory views showing an outline of a double tube in Example 2. FIG. 4A is a perspective view of the double tube, and FIG. 4B is a cross-sectional view of the double tube. . 5A is an enlarged view of the cross-sectional view taken along the line CC of FIG. 4B, and FIG. 5B is an enlarged view of the cross-sectional view taken along the line DD of FIG. 4B. 6A and 6B are explanatory views showing an outline of a double tube in Example 3. FIG. 6A is a perspective view of the double tube, and FIG. 6B is a cross-sectional view of the double tube. Fig. 6 (c) is a cross-sectional view of a double pipe, and shows an embodiment using an inner tube having a dent whose outer periphery is spirally recessed. Show. 7A is an enlarged view of the cross-sectional view taken along the line EE of FIG. 6B, and FIG. 7B is an enlarged view of the cross-sectional view taken along the line FF of FIG. 6C. 8A and 8B are explanatory views showing an outline of a double pipe according to a modification of the third embodiment. FIG. 8A is a perspective view of the double pipe, and FIG. It is sectional drawing. FIG. 9 is a cross-sectional view showing a mode in which a fixing process is performed after bending based on the dent of Example 2, FIG. 9 (a) shows a state before the fixing process, and FIG. 9 (b) shows a fixing process. It shows after the process. FIG. 10 is a cross-sectional view showing a double tube after a step of denting a part of the inner surface of the outer tube to the inside of the outer periphery of the inner tube in the fixing step as a modification of the second embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an example of a refrigeration cycle 1 having a double pipe 7 described below. The refrigeration cycle 1 is mounted on a vehicle and constitutes a part of a vehicle air conditioner (not shown).

The refrigeration cycle 1 includes a compressor 2 that compresses the refrigerant, a radiator 3 that cools the refrigerant compressed by the compressor 2, and an expansion device that expands the refrigerant cooled by the radiator 3 by decompressing the refrigerant. 4, an evaporator 5 that evaporates the refrigerant decompressed by the expansion device 4, and an accumulator that separates the refrigerant flowing out of the evaporator 5 into a gas layer and a liquid layer and sends the refrigerant in the gas layer to the compressor 2 6 and a double pipe 7 used as an internal heat exchanger for exchanging heat between the low-pressure refrigerant led from the accumulator 6 to the compressor 2 and the high-pressure refrigerant led from the radiator 3 to the expansion device 4. .

The compressor 2 and the radiator 3, the pipe through which the high-pressure refrigerant of the radiator 3 and the double pipe 7 flows, the pipe through which the high-pressure refrigerant of the double pipe 7 flows and the expansion device 4, the expansion device 4 and the evaporator 5, The evaporator 5 and the accumulator 6, the pipe through which the low-pressure refrigerant flows through the accumulator 6 and the double pipe 7, and the pipe through which the low-pressure refrigerant flows through the double pipe 7 and the compressor 2 are appropriately connected via the pipe 8. It is connected. Note that a portion of the pipe 8 from the discharge port of the compressor 2 to the inlet of the expansion device 4 forms a high-pressure side piping portion 8A, and of the pipe 8, the outlet from the expansion device 4 to the suction port of the compressor 2. The site | part has comprised the low voltage | pressure side piping part 8B.

2 and 3 show the first embodiment of the present invention, FIGS. 4 and 5 show the second embodiment of the present invention, and FIGS. 6 to 8 show the embodiment of the present invention. Example 3 and its variations are shown. Hereinafter, the first embodiment, the second embodiment, the third embodiment, and modifications thereof will be described.

As shown in FIGS. 2 and 3, the double pipe 7 of the first embodiment has an aluminum inner pipe 11 and an outer pipe 12, and the inner pipe 11 is inserted into the outer pipe 12. . The double pipe 7 may have a straight pipe portion 7A (FIG. 2) and a bent portion 7B (FIG. 9). And as FIG.2 and FIG.3 shows, the inner tube | pipe 11 of Example 1 is not formed in the outer periphery, but the outer periphery is circular in the cross section of any location. However, if the outer diameter of the inner tube 11 is smaller than the inner diameter of the outer tube 12, the inner tube 11 is similar to the inner tube 11 shown in FIGS. 6 (c), 7 (b) and 8 (b) described below. The outer periphery may have a dent that is spirally recessed.

In the first embodiment, the inner pipe 11 is connected to the low-pressure side pipe portion 8B on both sides in the extending direction, and the outer pipe 12 is connected to the high-pressure side via holes 12a formed on the outer surfaces near both ends in the extending direction. It is connected to the piping part 8A. Here, the connection method is not particularly limited as long as the inner pipe 11 is connected to the low-pressure side piping part 8B and the outer pipe 12 is connected to the high-pressure side piping part 8A. In the first embodiment, both sides of the outer tube 12 in the extending direction are closed by the inner tube 11, but if the refrigerant does not leak from both ends in the extending direction of the outer tube 12, the outer tube 12. The method of closing both sides in the extending direction is not particularly limited.

Thereby, the low-pressure refrigerant (second medium) flows through the inner pipe 11 of the double pipe 7, and the high-pressure refrigerant (first medium) flows between the outer pipe 12 and the inner pipe 11, Heat can be exchanged between the low-pressure refrigerant and the high-pressure refrigerant.

The inner tube 11 and the outer tube 12 of the double tube 7 are fixed by the following manufacturing method. A method of manufacturing the double pipe 7, in particular, a fixing process for fixing the inner pipe 11 and the outer pipe 12 by forming the recess 21 in the outer pipe 12 will be described below with reference to FIGS. 2 and 3.

First, in the insertion step, the inner tube 11 having an outer diameter smaller than the inner diameter of the outer tube 12 is inserted into the outer tube 12.

Next, in the fixing step, as shown in FIG. 2A, the dent forming tool 50 in which the rotating plate 52 is rotatably supported by the shaft portion 51 is moved upward with respect to the outer tube 12 in which the inner tube 11 is inserted. Then, a part of the outer tube 12 is further pushed into the inner tube 11. Then, the rotary plate 52 is pushed and moved along the extending direction of the outer tube 12. In this fixing step, even if the top surface 21a of the recess 21 of the outer tube 12 comes into contact with the outer periphery of the inner tube 11, the inner tube 11 is further pushed, and the inner tube 11 is pressed against the inner surface of the outer tube 12 opposite to the recess 21. Until the outer surface comes into contact, a part of the outer tube 12 is recessed with the rotating plate 52 of the recess forming device 50.

As a result, as shown in FIGS. 2 and 3, a recess 21 extending linearly along the extending direction of the outer tube 12 is formed above the outer tube 12, and the top surface 21a of the recess 21 and the outer tube Of the inner surface of 12, the opposite side of the recess 21 (below the inner surface of the outer tube 12) is in continuous contact with the outer surface of the inner tube 11 along the extending direction of the pipe. Therefore, at least in the straight pipe portion 7A of the double pipe 7, the inner pipe 11 is sandwiched from above and below between the top surface 21a of the recess 21 of the outer pipe 12 and the inner surface opposite to the recess 21 of the outer pipe 12. Therefore, it is fixed to the outer tube 12.

As described above, the insertion of the inner tube 11 into the outer tube 12 inserts the inner tube 11 having an inner diameter smaller than the inner diameter of the outer tube 12, so that the insertion process can be smoothly performed. Since the inner tube 11 and the outer tube 12 can be fixed by the fixing step for forming the recess 21, the double tube 7 can be easily manufactured. In addition, the inner tube 11 and the outer tube 12 can be fixed by the straight tube portion 7A of the double tube 7 regardless of the presence or absence of the bent portion.

In the fixing step, when forming the recess 21 in the outer tube 12, it is only necessary to form a recess 21 by recessing a part of the outer tube 12 from a certain direction. Thus, the present invention is not limited to the step of forming the recess 21. Although not shown, the recess 21 may be formed by indenting from a diagonally upper side, from the side, or from the lower side using a device such as the recess forming device 50. Furthermore, you may make it form the dent 21 with respect to the outer tube | pipe 12 from several directions. In this case, the inner tube 11 is fixed to the outer tube 12 in contact with the

top surfaces

21 a and 21 a of the plurality of recesses 21.

As shown in FIGS. 4 and 5, the double pipe 7 of the second embodiment has an inner pipe 11 and an outer pipe 12 made of aluminum, a straight pipe portion 7 </ b> A (FIG. 2), and a bent portion 7 </ b> B. The inner tube 11 may have a circular shape on the outer periphery of the inner tube 11 or the outer periphery of the inner tube 11 or may be the following FIG. 6 (c), FIG. 7 (b), FIG. The outer tube 12 may be connected to the low-pressure side piping portion 8B, and the outer tube 12 may be connected to the high-pressure side piping portion 8A. It is common with the double pipe 7 of Example 1 by the point which was made the structure. Therefore, about the structure and function similar to the double tube 7 of Example 1 among the double tubes 7 of Example 2, the description is abbreviate | omitted by attaching | subjecting the same code | symbol as the double tube 7 of Example 1. FIG.

The manufacturing method of the double pipe 7 of Example 2 also includes an insertion process and a fixing process. The insertion process is the same as that of the first embodiment, but the fixing process is different from that of the first embodiment. The manufacturing method of this double pipe 7, especially the fixing process different from the fixing process of the double pipe 7 of Example 1 is demonstrated below using FIG.4 and FIG.5.

Next, in the fixing step, a dent forming tool (not shown) suitable for forming a bottomed hole such as a rod with a sharp tip is not attached to the outer tube 12 into which the inner tube 11 is inserted. A plurality of bottomed holes 22 are formed in the outer tube 12 by pressing the outer tube 12 so that a part of the outer tube 12 is recessed from the outer surface of the tube 12 toward the center. In this fixing step, a part of the outer tube 12 is recessed until the top surface 22a of the bottomed hole 22 of the outer tube 12 contacts the outer periphery of the inner tube 11.

At this time, at least in the straight pipe portion 7A of the double pipe 7, for example, as shown in FIG. 4B, a plurality of bottomed holes 22 are arranged in two rows along the extending direction of the outer pipe 12. It forms so that it may become a shape. For example, one row of the outer tubes 12 is defined as one of the radial directions of the outer tube 12 (upward in the drawing), and the other row of the outer tubes 12 is defined as the other of the radial directions of the outer tube 12 (lower in the drawing). Two rows of bottomed holes 22 face each other.

As a result, as shown in FIGS. 4 and 5, the top surface 22 a of the bottomed hole 22 disposed in one of the radial directions of the outer tube 12 (upward in the drawing) and the other radial direction of the outer tube 12 ( The top surface 22a of the bottomed hole 22 disposed in the lower part of the drawing intermittently contacts the outer surface of the inner tube 11. Therefore, at least in the straight pipe portion 7A of the double pipe 7, the inner pipe 11 is sandwiched from both sides in the radial direction of the inner pipe 11 by the top surface 22a of the opposed bottomed hole 22, and thus is fixed to the outer pipe 12. Is done.

It should be noted that the intervals between the bottomed holes 22 arranged in a row in the outer tube 12 may be uniform or irregular. Further, the bottomed holes 22 provided on one side in the radial direction of the outer tube 12 and the bottomed holes 22 provided on the other side in the radial direction of the outer tube 12 may be shifted in the extending direction of the pipe. Further, a plurality of bottomed holes 22 may be formed in portions other than the upper and lower sides of the outer surface of the outer tube 12, and these bottomed holes 22 are irregularly scattered in the circumferential direction of the outer tube 12. You may do it. Even in such an arrangement of the bottomed hole 22, at least in the straight pipe portion 7 </ b> A of the double pipe 7, the inner pipe 11 is arranged in the radial direction of the inner pipe 11 by the top surface 22 a of the bottomed hole 22 of the outer pipe 12. Since it is sandwiched from at least both sides, it can be fixed to the outer tube 12. Moreover, since the top surface 22a of the bottomed hole 22 of the outer tube 12 contacts the outer surface of the inner tube 11 at a plurality of locations, the inner tube 11 can be fixed to the outer tube 12 more reliably. In particular, the bottomed hole 22 has three or more locations in the circumferential direction of the outer tube 12, and the angle formed by the intersection of the virtual line connecting the center of the outer tube 12 and each bottomed hole 22 is less than 180 °. For example, the inner tube 11 can be sandwiched by the top surfaces 22 a of the three or more bottomed holes 22, and the inner tube 11 can be more stably fixed to the outer tube 12. Further, since the inner tube 11 can be positioned substantially at the center of the outer tube 12 (the axial center point of the inner tube 11 can be positioned in the vicinity of the axial center point of the outer tube 12), the outer tube 12 can be positioned. A flow path 35 of a high-pressure refrigerant (first medium) formed between the inner pipe 11 and the inner pipe 11 can be formed around the inner pipe 11, and a high-pressure refrigerant (first medium) and a low-pressure refrigerant (second medium) The efficiency of heat exchange with the medium) can be improved.

As shown in FIGS. 6, 7, and 8, the double pipe 7 according to the third embodiment and the modified example has an aluminum inner pipe 11 and an outer pipe 12. 2) and a bent portion 7B (FIG. 9), the inner tube 11 may have a circular cross section at any point, or the outer periphery may be circular, or FIG. 6 (c) and FIG. b) As in the case of the inner tube 11 in FIG. 8B, the outer tube may have a recess with a spiral recess, the inner tube 11 is connected to the low-pressure side pipe 8B, and the outer tube 12 is connected to the high-pressure side. It is common with the double pipe 7 of Example 1 and Example 2 by the point connected to 8 A of piping parts. Therefore, about the structure and function similar to the double pipe 7 of Example 1 or Example 2 among the double pipes 7 of Example 3 and its modification, it is the same as that of the double pipe 7 of Example 1 and Example 2. The description is abbreviate | omitted by attaching | subjecting the same code | symbol.

The manufacturing method of the double pipe 7 of Example 3 and its modification also has an insertion process and a fixing process. The insertion process is the same as in Example 1 and Example 2, but the fixing process is different from Example 1 and Example 2. The manufacturing method of this double pipe 7, especially the fixing process different from the fixing process of the double pipe 7 of Example 1 or Example 2 is demonstrated below using FIG.6, FIG.7 and FIG.8.

As shown in FIGS. 6B and 7A, the inner tube 11 of the double tube 7 of the third embodiment has a circular outer periphery and has no recess, or FIG. ) And FIG. 7B, an inner tube 11 having a recess 31 whose outer periphery is recessed spirally is used. In the inner tube 11 having the recess 31, the recess 31 is formed in advance before being inserted into the outer tube 12. The formation of the recess 31 of the inner tube 11 is performed by, for example, mounting a spiral recess forming device that forms a spiral recess on the outer periphery of the inner tube 11 and rotating the periphery of the inner tube 11 in the axial direction of the inner tube 11. Is done. Then, by forming a spiral recess 31 on the outer periphery of the inner tube 11, the inner tube 11 has a concave portion 31a and a convex portion 31b on the outer periphery, as shown in FIGS. 6 (c) and 7 (b). Are alternately formed along the extending direction of the inner tube 11. Since the helical dent forming device is a known device shown in FIG. 7 of the cited document 1, for example, the description of the configuration is omitted.

First, in the insertion step, the inner tube 11 having an outer diameter smaller than the inner diameter of the outer tube 12 is inserted into the outer tube 12. Even if the inner tube 11 has or does not have the recess 31 whose outer periphery is spirally recessed, the outer diameter of the inner tube 11 is smaller than the inner diameter of the outer tube 12.

Next, in the fixing step, for example, the above-described helical dent forming device (not shown) is mounted on the outer periphery of the outer tube 12 into which the inner tube 11 is inserted, and the outer tube 12 is rotated while rotating around the outer tube 12. By displacing in the axial direction, the outer tube 12 is formed with a recess 23 that is spirally recessed. In this fixing step, a part of the outer tube 12 is recessed so that the top surface 23 a of the recess 23 that is recessed in the spiral shape of the outer tube 12 continuously contacts the outer surface of the inner tube 11.

Thereby, as shown in FIGS. 6B and 7A, the top surface 23a of the recess 23 of the outer tube 12 continuously contacts the outer surface of the inner tube 11, and the inner tube 11 is in contact with the outer tube 12. Fixed to. Moreover, a flow path 35 extending in a spiral shape is formed between the inner tube 11 and the outer tube 12 on the inner surface other than the top surface 23a of the recess 23 of the outer tube 12 and the outer surface of the inner tube 11, and this spiral shape is formed. The high-pressure refrigerant (first medium) flows along the flow path 35.

Even when using the inner tube 11 having the recess 31 whose outer periphery is spirally recessed, first, an insertion step of inserting the inner tube 11 into the outer tube 12 is performed. Next, in the fixing step, for example, the above-described helical recessing device (not shown) is mounted on the outer periphery of the outer tube 12 in which the inner tube 11 is inserted, and the outer tube 12 is rotated while rotating around the outer tube 12. Is formed in the outer tube 12 to form a recess 23 that is spirally recessed. In this fixing step, the top surface 23a of the recess 23 recessed in the spiral shape of the outer tube 12 continuously abuts on the outer surface of the inner tube 11, and the pitch of the recess 23 formed in the outer tube 12 and the inner tube 11 are preliminarily set. The pitch of the provided spiral recesses 31 is adjusted to be substantially the same so that the top surface 23a of the spiral recess 23 of the outer tube 12 continuously contacts the spiral convex portion 31b of the inner tube 11. The outer tube 12 is recessed in a spiral shape.

Accordingly, as shown in FIGS. 6C and 7B, the top surface 23a of the recess 23 of the outer tube 12 continuously contacts the convex portion 31b of the inner tube 11 (the outer surface of the inner tube 11). Because of the contact, the inner tube 11 is fixed to the outer tube 12. Moreover, a spirally extending flow path 35 is formed between the inner tube 11 and the outer tube 12 on the inner surface other than the top surface 23 a of the recess 23 of the outer tube 12 and the outer surface of the recessed portion 31 a of the inner tube 11. The high-pressure refrigerant (first medium) flows along the spiral flow path 35.

However, as shown in a modification of the third embodiment shown in FIG. 8, even when the inner tube 11 having the recess 31 whose outer periphery is spirally recessed is inserted into the outer tube 12, The pitch of the spiral recesses 23 to be formed is not necessarily the same as the interval of the spiral recesses 31 of the inner tube 11 by making the pitch larger (longer) than the interval of the spiral recesses 31 of the inner tube 11. . By making the pitch larger (longer), the processing length of the spiral recess 23 formed in the outer tube 12 can be shortened, and productivity can be improved. Conversely, the pitch of the spiral recesses 23 formed in the outer tube 12 may be made smaller (shorter) than the interval between the spiral recesses 31 of the inner tube 11. The first medium that flows between the outer tube 12 and the inner tube 11 by reducing (shortening) the pitch is secured for a longer period of time in contact with the outer surface of the inner tube 11, and the first medium that flows through the inner tube 11. Exchange of heat with the second medium is promoted, and the heat exchange performance of the double pipe 7 can be improved.

Also in the configuration of the modified example of Example 3 as described above, as shown in FIG. 8B, the top surface 23 a of the recess 23 of the outer tube 12 is a part of the plurality of convex portions 31 b of the inner tube 11. The inner tube 11 is fixed to the outer tube 12 by abutting against the convex portion 31b. In addition, the spiral recess 23 of the outer tube 12 and the spiral recess 31 of the inner tube 11 serve as a guide for refrigerant flow, and the high-pressure refrigerant (first medium) flows between the inner tube 11 and the outer tube 12. It becomes easy to flow in a spiral.

As the first embodiment, the second embodiment, the third embodiment, and the modification thereof, the straight pipe portion 7A of the double pipe 7 is illustrated, and the method of fixing the inner pipe 11 and the outer pipe 12 has been described. Even if the heavy pipe 7 has the bent portion 7B, the inner pipe 11 and the outer pipe 12 can be fixed using the insertion process and the fixing process described so far. A method of fixing the inner tube 11 and the outer tube 12 in the bent portion 7B of the double tube 7 will be described below with an example in which the bottomed hole 22 is formed in the outer tube 12. In addition, as for the inner tube | pipe 11, even if it sees the cross section of any location, the outer tube | pipe 11 whose outer periphery is circular shape is illustrated.

First, an insertion step of inserting the inner tube 11 having an outer diameter smaller than the inner diameter of the outer tube 12 into the outer tube 12 is performed. Next, as shown in FIG. 9A, a bending process is performed in which the outer tube 12 in which the inner tube 11 is inserted is bent or curved at a predetermined angle. When the bottomed hole 22 is formed in the outer tube 12, for example, as shown in FIG. 9B, the inner peripheral side of the outer tube 12 (the portion bent or curved at a predetermined angle). A bottomed hole 22 is formed at a predetermined location on the side relatively closer to the bending center, and the outer peripheral side of the outer tube 12 (a side far from the bending center of a portion bent or curved at a predetermined angle) And a fixing step of forming the bottomed holes 22 at two predetermined positions on both sides in the extending direction of the outer tube 12 with respect to the bottomed holes 22 on the inner peripheral side of the outer tube 12 is performed. Even in this fixing step, the bottomed hole 22 is formed by denting a part of the outer tube 12 until the top surface 22a of the bottomed hole 22 of the outer tube 12 contacts the outer periphery of the inner tube 11.

9B, the inner tube 11 is supported by the top surfaces 22a of the plurality of bottomed holes 22 from the outer peripheral side and the inner peripheral side of the outer tube 12, so that the inner tube 11 is It is fixed to the outer tube 12. Therefore, even after the outer tube 12 into which the inner tube 11 is inserted is bent or bent by a bending process, the outer tube 12 and the inner tube 11 can be easily fixed by the fixing process.

In addition, although the aspect which forms the bottomed hole 22 in the outer pipe | tube 12 was shown as a fixing process which fixes the outer pipe | tube 12 and the inner pipe | tube 11, it is not necessarily limited to this aspect. Although not shown, a fixing step of forming the recess 21 by denting the outer tube 12 along the extending direction of the outer tube 12 and a fixing step of forming the recess 23 by spirally denting the outer tube 12. It may be performed after bending.

In FIG. 10, as a modification of the second embodiment, a part of the outer tube 12 is recessed so that the top surface 22 a of the bottomed hole 22 of the outer tube 12 reaches the inner side of the outer periphery of the inner tube 11. Thus, a state is shown in which a recess 32 is formed also in the inner tube 11 and the top surface 22a of the bottomed hole 22 and the recess 32 of the inner tube 11 are fitted. Thereby, the outer tube | pipe 12 and the inner tube | pipe 11 can be fixed easily and firmly.

Although not shown, a part of the outer tube 12 is recessed in the extending direction of the outer tube 12 such that the top surface 21 a of the recess 21 reaches the inner side of the outer periphery of the inner tube 11, or the top surface of the recess 23. The outer tube 12 may be helically recessed so that 23a reaches the inner side of the outer periphery of the inner tube 11. Also according to these aspects, the recess 32 is formed in the inner tube 11, and the outer tube 12 and the inner tube 11 are fitted by the recess 32 and the top surface 21 a of the recess 21 or the recess 32 and the top surface 23 a of the recess 23. Therefore, the outer tube 12 and the inner tube 11 can be easily and firmly fixed.

In addition, in the fixing process in which a part of the outer tube 12 is pushed into the inner tube 11 so far, a mode in which the outer tube 12 is recessed along the extending direction of the outer tube and a mode in which a plurality of bottomed holes are scattered are formed. In addition, although the spirally recessed mode has been described, a plurality of modes may be applied to one double pipe 7 as necessary.

For example, in the straight pipe portion 7A, a spiral recess 23 is formed by using a spiral recess forming device, while a plurality of bottomed

holes

22 and 22 are formed in a bent portion 7B that is bent or curved at a predetermined angle. To do. In this way, an appropriate fixing method can be selected according to the shape of the double pipe 7.

In addition, for example, in the fixing step, after first performing the step of firmly fixing the outer tube 12 and the inner tube 11 as shown in FIG. May be implemented. Since the position of the inner tube 11 can be firmly fixed to the outer tube 12 at an early stage, unintentional displacement between the outer tube 12 and the inner tube 11 in the subsequent fixing process can be prevented.

DESCRIPTION OF SYMBOLS 1 Refrigeration cycle 7 Double pipe 7A Straight pipe part 7B Bending part 8 Piping 8A High pressure side piping part 8B Low pressure side piping part 11 Inner pipe 12 Outer pipe 21 Outer pipe dent 21a Depressed top surface 22 Bottom hole 22a of outer pipe Top surface 23 of the bottomed hole Depression 23a of the outer tube Top surface 31 of the recess Inner tube recess 32 Inner tube recess

Claims

A method of manufacturing a double pipe used as an internal heat exchanger of a refrigeration cycle mounted on a vehicle,
An insertion step of inserting an inner tube having an outer diameter smaller than the inner diameter of the outer tube into the outer tube;
A fixing step of fixing the outer tube and the inner tube by recessing a part of the outer tube until coming into contact with the outer periphery of the inner tube;
A method for producing a double pipe, comprising:
The method for manufacturing a double pipe according to claim 1, wherein the fixing step is a step of denting the outer pipe along an extending direction of the outer pipe.
The method for manufacturing a double tube according to claim 1, wherein the fixing step is a step of denting the outer tube so that a plurality of bottomed holes are scattered.
The method for manufacturing a double pipe according to claim 1, wherein the fixing step is a step of concavely forming the outer tube in a spiral shape.
The fixing step is a step of continuously abutting the top surface of the spirally recessed portion of the outer tube against the inner tube when the outer tube is recessed helically. The method for producing a double pipe according to claim 4.
The method for manufacturing a double pipe according to any one of claims 1 to 5, wherein the inner pipe has a recess whose outer periphery is spirally recessed.
As a step performed between the insertion step and the fixing step, a bending process for bending or bending the outer tube into which the inner tube is inserted at a predetermined angle,
The method for manufacturing a double pipe according to any one of claims 1 to 6, wherein the fixing step is performed on a portion of the outer pipe bent or bent by the bending process.
8. The fixing step according to claim 1, wherein a part of the outer tube is recessed until a part of the outer tube reaches the inside of the outer periphery of the inner tube. A method for producing a double pipe according to claim 1.
The method for manufacturing a double pipe according to any one of claims 1 to 8, wherein the outer pipe and the inner pipe are made of aluminum.