JP2020180767A - Double pipe joint structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joint structure with a connecting pipe capable of obtaining sufficient heat exchange performance for the entire double pipe and increasing the degree of freedom in layout. SOLUTION: In a joint structure of a heat exchanger double pipe composed of an inner pipe 1 and an outer pipe 2 provided with a plurality of spiral uneven portions 11 and a connecting pipe 3, the inner pipe 1 has an annular seal. The expansion portion 13 and the end portion 11b of the uneven portion 11 are provided close to each other. At the end 2b of the outer pipe 2, a fitting connection portion 21 that surrounds the connection terminal of the connection pipe 3 and the sealing expansion portion 13 of the inner pipe 1, and the wall surface of the inner pipe 1 and the outer pipe from the center of the inner pipe 1 are provided. A fluid guiding portion 22 for guiding the fluid from the end port 3b of the connecting pipe 3 to each swirling flow path is provided so as to surround the difference in the distance to the wall surface of the connecting pipe 3 so as to gradually increase toward the connecting pipe 3. The fluid guide portion 22 is provided with a tapered main wall portion 24 connected to the outer pipe 2 outside the fluid guide portion 22 from the maximum diameter portion 24a having the maximum cross-sectional area on one side, and is connected to the other side. A fluid wall portion connected to the pipe 3 is arranged. [Selection diagram] Fig. 1

Description

The present invention relates to a joint structure of a double pipe and a connecting pipe used as a heat exchanger in which a spiral heat exchange passage is formed between an inner pipe and an outer pipe.

In the heat exchange system of an automobile air conditioner, as a small heat exchanger with high heat exchange efficiency, one fluid for heat exchange is circulated in the spiral heat exchange passage between the inner pipe and the outer pipe, and the other. Double pipes are often used to exchange heat between the two fluids by circulating the fluids in the inner pipe.
The spiral heat exchange passage is formed by spiral uneven portions provided in the inner pipe, and connecting pipes for inlet and outlet of the fluid flowing through the heat exchange passage are connected to both ends of the double pipe. Helix.
The joint connecting the double pipe and the connecting pipe generally has a structure in which the connecting pipe is connected upright to the connecting hole drilled at the end of the outer pipe, and has a spiral heat exchange passage. There is a problem that the flow of the fluid is hindered by the sudden change of direction of the connecting portion between the inlet and the outlet of the fluid swirled in, and the heat exchange performance is deteriorated.

As a technique for improving this problem, a technique is known in which an annular groove is provided on the peripheral surface of the inner pipe at a position facing the end port of the connecting pipe to avoid a sudden change of direction of the fluid. However, even with this technology, since the basic structure that the connecting pipes are orthogonal is maintained, a sudden change of direction of the fluid is unavoidable, and not only is it not a fundamental improvement, but also a sudden change of direction is avoided. Therefore, the wider the width of the annular groove, the lower the strength, and a new problem arises in which the pipe wall in the groove is easily deformed by the flow pressure received from the fluid.

On the other hand, the inventor of the present application previously proposed the joint structure of the double pipe of Patent Document 1 below, connected the connecting pipe to the end of the outer pipe of the double pipe in parallel in the axial direction, and connected the connecting pipe to the connecting pipe. By providing a connected tubular flow guide, the obstacles to the flowability due to the sudden change of direction of the flow path are eliminated, the fluid flowability is improved, and sufficient heat exchange performance can be obtained.
Further, since it is no longer necessary to provide the annular groove in the conventional joint structure, the problem due to the decrease in the strength of the inner pipe has been solved.

However, in the technique of Patent Document 1, since the tubular flow guide portion is formed long in the axial direction so as to surely reach the swirling flow path between the spiral concave-convex portions, the number of concave-convex portions is large. The longer it becomes, the longer the length of the distribution guide that covers each uneven part must be increased, and if the length of the distribution guide is increased, the increased amount within the limited length of the double pipe. There is a problem that the range in which the double pipe can be freely bent is narrowed, and the freedom of layout when assembling to an air conditioner or the like is lost.
In addition, since the end of the swirling flow path is closed by the expansion portion for sealing, a dead space is partially created on the back side of the distribution guide portion, where the heat exchange function is impaired and the heat exchange efficiency is lowered. was there.

Japanese Unexamined Patent Publication No. 2013-124854

The present invention improves the problem of the joint structure of the double pipe of Patent Document 1 and obtains sufficient heat exchange performance by allowing the fluid to flow through the joint with the connecting pipe to the end of the double pipe. An object of the present invention is to provide a double pipe joint structure capable of increasing the degree of freedom in assembly layout at the place of use without causing a decrease in the strength of the inner pipe.

In order to solve the above problems, in the invention of claim 1 in the double pipe joint structure of the present invention, a heat exchange passage is formed between the inner pipe and the outer pipe having a plurality of spiral uneven portions. In the joint structure of the double pipe in which the inlet and the outlet of the fluid flowing through the heat exchange passage are connected to the double pipe for the heat exchanger, the inner pipe has an inner wall of the outer pipe end. A sealing expansion portion is provided in which the facing portion of the pipe is bulged in an annular shape, the uneven portion thereof is provided with its end portion close to the sealing expansion portion, and the connecting pipe is provided with an outer portion at the end portion. A substantially D-shaped irregularly shaped connecting terminal surrounded by the inner shape of the pipe end and the outer shape of the sealing expansion portion of the inner pipe is provided, and the outer pipe is provided with the connecting pipe at the end thereof. The Dharma-shaped fitting connection portion that surrounds the connection terminal and the expansion portion for sealing of the inner pipe, and the outside of the end portion of the connection pipe and the end portion of the uneven portion of the inner pipe are covered from the end opening of the connection pipe. A fluid guiding portion for forming a guiding passage for guiding the fluid to each swirling flow path formed between the uneven portions is provided, and the fluid guiding portion has a maximum diameter portion with an circumscribing circle at the top of the uneven portion of the inner pipe. It has a substantially circular shape with a cross-sectional area larger than the total cross-sectional area of multiple swirling flow paths, and the difference in the distance from the center of the inner pipe to the wall surface of the inner pipe and the wall surface of the outer pipe gradually increases toward the connecting pipe. A guide passage is formed by surrounding each swirl flow path, and a tapered main wall portion connected to an outer pipe outside the fluid guide portion is arranged on one side from the maximum diameter portion, and a connection pipe is arranged on the other side. It is characterized by arranging a sub-wall part that connects to.

The invention of claim 2 is characterized in that, in the above invention, the maximum diameter of the main wall portion is smaller than the total value of the outer diameters of the expansion portion for sealing and the connecting pipe.

The invention of claim 3 is characterized in that, in the above invention, the end portion of the uneven portion of the inner pipe and the expansion portion for sealing are brought close to each other via an annular groove.

The invention of claim 4 is characterized in that, in the above invention, the diameter of the inner wall of the main wall portion near the uneven portion of the inner pipe is enlarged.

The present invention has the above configuration, and the fluid in the fluid guide provided at the end of the outer pipe flows from the connecting pipe inserted at the end of the outer pipe in the same axial direction as the double pipe, and at that time, the main wall. Since the portion has a diameter larger than the outer circumference of the inner pipe over the entire length, it passes through a wide guide passage in front of the connecting pipe, is guided to the tapered main wall portion, and is divided into each swirling flow path for distribution. Therefore, it is possible to smoothly distribute the product without causing a sudden change of direction.
Then, in the fluid guiding portion, a guiding passage surrounding each swirling flow path is formed so that the difference in distance from the center of the inner pipe to the wall surface of the inner pipe and the wall surface of the outer pipe gradually increases toward the connecting pipe.
For this reason, a sufficient amount of fluid is supplied while maintaining a gradually increasing wide space to the end ports of a plurality of swirling flow paths located closer to the connection pipe where the end port of the swirling flow path serving as the fluid intake is present. It will be possible. On the other hand, since the width of the guide passage gradually narrows with respect to the end ports of the plurality of swirl passages located farther from the tangent pipe, the width of the guide passage gradually narrows, so that the guide passage is guided by the circular main wall and converges to the narrow side so as to go around. While circulating in the circumferential direction. That is, the fluid is smoothly guided by the guide passage surrounding each swirling flow path, and it is possible to accurately supply the required amount of fluid according to the required amount.
At that time, since the fluid circulates around the end of the uneven portion located at a position away from the end opening of the connecting portion in the circumferential direction, no dead space for the fluid to stay is generated in all the swirling flow paths.
Further, in the fluid guide portion, all swirling flow paths are provided with a substantially circular maximum diameter portion guide passage between the tapered main wall portion connected to the outer pipe outside the fluid guide portion and the slave wall portion connected to the connecting pipe. Since the cross-sectional area is larger than the total cross-sectional area of the guide passage, the cross-sectional area of the guide passage is once increased at the maximum diameter portion directly flowing from the connecting pipe, and is required in all the swivel flow paths in the guide passage. A sufficient amount of fluid can be circulated. The fluid passes through the increased guidance passage, is guided by the tapered slope of the main wall that gradually narrows, converges in the axial direction, and finally splits from the end of the main wall into all the swirling flow paths. It will be distributed smoothly.

In addition, since the guide passage has a margin for circulation in the wide space on the front side of the connecting pipe, the flow rate to each swirling flow path away from the front side of the connecting pipe in the circumferential direction can be small. By forming the connection pipe side that requires a large flow rate to be wider and the side far from the connection pipe that requires a small flow rate to be gradually narrowed, it is possible to reduce the outer diameter of the maximum diameter portion.
Therefore, the outer diameter of the joint portion can be made compact, and the degree of freedom in the assembly layout at the place of use can be increased.
Then, the guidance passage having the guidance function for smoothly guiding the flow to each swirl flow path as described above generates a large flow resistance in the joint between the swirl flow path and the flow path due to a sudden change of direction. It is possible to smoothly circulate the fluid throughout the double pipe without causing it.

In addition, since the main wall portion allows the required amount of fluid to flow with a margin in the wide maximum diameter portion, the amount of fluid flowing into each swirling flow path is small on the tapered end side of the main wall portion. No need to lengthen the main wall unnecessarily.
Therefore, even if the number of spiral concavo-convex portions is increased, it is not necessary to extend the main wall portion in the axial direction according to the increased number, and the volume of the maximum diameter portion of the guide passage is increased. , The fluid guide can be shortened.
By shortening the area of the joint part in the axial direction, it is possible to bend it near the end of the main wall part according to the shape of the space of the place of use, and the degree of freedom of assembly layout is increased so that it can be used even in a narrow place. It becomes possible to increase.

Further, since the end of the uneven portion of the inner pipe is close to the expanding portion for sealing, a wide flat portion that becomes fragile is not formed in the inner pipe of the joint between the double pipe and the connecting pipe, and it is thin and soft. Even if a large pressure is applied from the fluid to the inner tube made of aluminum, it will not be deformed or damaged.

In the invention of claim 2, the maximum diameter of the main wall portion is set to a diameter smaller than the total value of the expansion portion for sealing and the outer diameter of the connecting pipe, so that the axial length of the fluid guiding portion is shortened to form a joint. Not only can the whole be shortened, but the outer diameter of the maximum diameter portion of the joint portion can be set to be small so that the diameter can be made compact, and the degree of freedom in layout can be further increased.

According to the third aspect of the present invention, the end of the uneven portion of the inner pipe and the expansion portion for sealing are brought close to each other through the annular groove, so that the end of the uneven portion of the inner pipe is also from the annular groove. It is possible to distribute more to the end of the swirling flow path between the parts.
As a result, the axial length of the fluid guide portion can be further shortened to make the entire joint more compact, and the degree of freedom in layout can be further increased.

According to the fourth aspect of the present invention, the diameter of the inner wall of the main wall portion close to the uneven portion of the inner pipe is enlarged, so that the enlarged portion also covers each swirling flow path between the ends of the uneven portion of the inner pipe. It will be possible to distribute more.
As a result, the axial length of the fluid guide portion can be further shortened to make the entire joint more compact, and the degree of freedom in layout can be further increased.

It is a vertical section side view which shows the state which traversed the outer tube by the line AA of FIG. 3 of the 1st example of this invention. It is a cross-sectional plan view which shows the state which crossed the outer pipe by the line BB of FIG. 3 of the 1st example. It is a front surface which saw the joint of 1st example and 2nd example from the end direction of the outer pipe. It is a perspective view seen obliquely from the end side of the 1st example. It is a top view seen from the side which connected the connection pipe of 1st example. In FIG. 1 of the first example, (a) is cut by the CC line, (b) is cut by the DD line, (c) is cut by the EE line, and (2) is the FF. It is a circular cross-sectional view which shows the cross section of each part cut by a line. It is a vertical section side view which shows the state which traversed the outer tube by the line AA of FIG. 3 of the 2nd example of this invention. It is a cross-sectional plan view which shows the state which crossed the outer pipe by the line BB of FIG. 3 of the 2nd example. FIG. 7 (a) of FIG. 7 of the second example is a circular cross-sectional view showing a cross section of each portion cut along the GG line and (b) is a cross-sectional view of each portion cut along the HH line. It is a vertical section side view which shows the state which traversed the outer tube by the line I-I of FIG. 11 of the 3rd example of this invention. This is the front surface of the joint of the third example as viewed from the end direction of the outer pipe. FIG. 10A of FIG. 10 of the third example is a circular cross-sectional view showing a cross section of each portion cut along the JJ line and (b).

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
First, the joint structure will be described in the first example, which is the basic embodiment of the present invention.
1 to 6 show a first example thereof.
Originally, the use of the double pipe is not limited to the top, bottom, left and right, but below, based on FIG. 1 which is a side view, the upper side to which the connecting pipe is connected is the upper side and the lower side is the lower side, and the front surface. Based on FIG. 3, the left side when the connecting pipe is connected to the upper side is the left side, the right side is the right side, and the direction b of the center line of the double pipe shown in FIG. 4 is the axial direction. I will explain it.

As shown in FIGS. 1 and 2, the present invention is inserted and fixed to the outer tube 2, the inner tube 1 inserted into the outer tube 2, and the extended end 2b of the outer tube 2. It is a double pipe joint structure composed of a connecting pipe 3.
The connecting pipe 3 is connected to the inlet side and the outlet side in order to allow fluid to flow through the heat exchange passage 5 formed between the outer pipe 2 and the inner pipe 1, and the shaft of the end portion 3a of the connecting pipe 3 is connected. The direction a is fixed so as to be parallel to the axial direction b of the double pipe.
As the raw material to be used, an aluminum tube having a high thermal conductivity is used.
And for example, the thickness of the wall surface is 1.5 mm for the outer pipe and the inner pipe, and 1 mm for the connecting pipe. The diameter of the outer pipe is 19 mm, that of the inner pipe is 12 mm, and that of the connecting pipe is 6 mm. In this case, the cross-sectional area of the inner diameter of the connecting pipe is about 28 mm ² .

As shown in FIGS. 1 and 2, the inner pipe 1 has a plurality of spiral concavo-convex portions 11 in which the wall surface 1a of the raw pipe is raised toward the outer circumference in parallel, and the length between both end portions 2b of the outer pipe 2. It is provided so as to continuously swivel the pipe wall to a very slightly shorter length without breaking in the middle.
Then, the raw pipe portion connected to the end portion 11b of the uneven portion 11 of the inner pipe 1 is used for an annular seal in which the pipe wall is bulged once in a state of being close to both end portions 11b of the uneven portion 11. The expansion portion 13 is formed, and at that time, the expansion portion 13 for sealing is formed at a portion facing the inner wall surface of the end portion 2b of the outer pipe 2.
It should be noted that FIGS. 1 and 2 show only one side of the double pipe, and each of the following figures also shows only one side of the double pipe. Both sides of the double pipe are the inlet side and the outlet side of the outer pipe 2, and both sides have the same structure. Therefore, the structure on one side will be described below as shown in FIGS. 1 and 2.

Both ends 11b of the uneven portion 11 of the inner pipe 1 and the sealing expansion portion 13 are brought close to each other, but the approaching state is either in a state of being in contact with each other or in a state of being slightly separated from each other. ..
The first example is an example of a state of contact, and the state of no contact will be described later in the second example.
In this first example, there is no raw pipe portion between the end portion 11b of the uneven portion 11 and the side portion of the sealing expansion portion 13, and the end portion 11b of the uneven portion 11 and the side portion of the sealing expansion portion 13 are in contact with each other. It is a structure that rises from the pipe wall.
For this reason, the structure is reinforced by the rising portions on both sides thereof, and the wall surface is reinforced, and deformation due to pressurization does not occur at the contacted portions.

The method of forming the uneven portion 11 and the expanding portion 13 for sealing is, for example, to insert the uneven portion 11 into a mold in which the uneven portion corresponding to each uneven portion 11 is formed, and apply pressure to the inside of the inner pipe 1 to form a pipe wall. A method of swelling or the like is possible.
The uneven portion 11 has, for example, three uneven portions 11 bulged in parallel in a spiral shape at a pitch of 38 mm, the width of the uneven portion 11 is 9 mm, the height is 2 mm, and the uneven portion 11 is not bulged. The bottom width of the recess 12 between the remaining uneven portions 11 is 4 mm. If the total cross-sectional area between the uneven portions 11 is 28 mm ² , it is the same as the cross-sectional area of the inner diameter of the connecting pipe 3. The sealing expansion portion 13 forms a tube wall in an annular shape with a width of 15 mm and a height of 2 mm, which is the same as the protrusion height of the uneven portion 11.

As shown in FIG. 1 and FIG. 6 (2), the outer pipe 2 uses a raw pipe having a diameter capable of contacting the top portion 11a of the uneven portion 11 of the inner pipe 1 inserted therein with the inner wall surface. ..
For example, when the outer diameter of the top portion 11a of the uneven portion 11 of the inner pipe 1 is 19 mm, the diameter of the outer pipe 2 is also 19 mm. That is, the inner diameter of the outer pipe 2 and the outer diameter of the top portion 11a of the uneven portion 11 of the inner pipe are made to match.
As a result, when the inner pipe 1 is fitted into the outer pipe 2, a plurality of independent swirling flow paths are provided between the spiral uneven portions 11 of the inner pipe 1 and the inner wall 2a of the outer pipe 2. A heat exchange passage 5 having 51a, 51b, and 51c is formed.
(2) of FIGS. 1, 2 and 6 shows an embodiment in which three swirling flow paths 51a, 51b and 51c are formed between the three uneven portions 11. The number of uneven portions 11 is a plurality, but the practical range is about 2 to 5.

The end portion 2b of the outer pipe 2 has a tapered diameter, and as shown in FIGS. 1 and 2, the end portion 3a of the connecting pipe 3 is inserted between the end portion 2b and the sealing expansion portion 13 of the inner pipe 1. A fitting connection portion 21 having a possible width and a fluid guiding portion 22 that allows fluid to flow from the end portion 3a of the connecting pipe 3 to the plurality of swirling flow paths 51a, 51b, 51c following the fitting connection portion 21. Form.

The connecting pipe 3 forms a connecting terminal 31 at its end 3a for inserting into the end 2b of the expanded outer pipe 2.
FIG. 4 shows a state before the connection terminal 31 of the connection pipe 3 is inserted. The connection terminal 31 is deformed into a deformed shape (D shape) surrounded by the inner shape of the fitting connection portion 21 of the end portion 1b of the outer pipe 2 and the outer shape of the sealing expansion portion 13 of the inner pipe 1. The irregularly shaped portion 31a is formed with a concave surface portion 31b that can be brought into close contact with the outer peripheral surface of the sealing expansion portion 13.
The irregularly shaped portion 31a is expanded so that both sides of the concave surface portion 31b protrude downward to eliminate the decrease in volume due to deformation, and the concave surface portion 31b can be stably joined to the sealing expansion portion 13 of the inner pipe 1. To do so.
Further, since the concave surface portion 31b of the irregularly shaped portion 31a is widely in contact with the expanded end portion 2b of the outer pipe 2, there is a defect in brazing (the brazing material is indicated by reference numeral 6 in FIG. 1) when fixing each pipe. It does not occur, and the sealing property of each connecting portion of the inner pipe 1, the outer pipe 2 and the connecting pipe 3 is improved.

As shown in FIG. 6A, the connection terminal 31 of the connection pipe 3 is inserted into the fitting connection portion 21 of the outer pipe 2 and has a concave surface on the outer peripheral surface 13a of the sealing expansion portion 13 of the inner pipe 1. The portion 31b is brought into contact with each other, and at that time, as shown in FIG. 4, the center line a of the connected connecting pipe 3 is substantially parallel to the center line b of the inner pipe 1 of the double pipe.
Therefore, since the connecting pipe 3 is closely connected to the inner pipe 1, the circumference of the joint can be made compact.
Further, by connecting the connecting pipe 3 to the end 2b of the outer pipe 2 substantially parallel to the inner pipe 1, the fluid can flow smoothly without causing a sudden change of direction.

As shown in FIG. 1, the end portion 2b of the outer pipe 2 has a wide side into which the connection terminal 31 of the connection pipe 3 is inserted when expanded in a tapered shape, and the seal expansion portion 13 into which the connection terminal 31 is not inserted. The center line of the tapered pipe is inclined toward the upper connecting pipe 3 side so that the side surrounding the pipe is narrowed.
Then, a fitting connection portion 21 that can be in close contact with both outer wall surfaces of the sealing expansion portion 13 and the connection pipe 3 is formed on the end opening 2c side of the expansion portion of the outer pipe 2.

The method of forming the fitting connection portion 21 is to insert a mold corresponding to the connection pipe 3 and the expansion portion 13 for sealing into the expansion portion of the outer pipe, pressurize the outer peripheral side of the end portion 2b of the outer pipe 2, and press the metal. It is possible to dent it so that it fits the outer shape of the mold.
Then, a narrowing portion 26 that is largely narrowed with respect to the expansion portion 13 for sealing is formed on one side, and a narrowing portion 27 that is largely narrowed with respect to the connecting terminal 31 is formed on the other side. The inner wall is surrounded so as to be in contact with the sealing expansion portion 13 of the inner pipe 1, and the end opening 2c of the expanded outer pipe 2 has a Dharma shape.
As shown in (a) of FIGS. 3 and 6, the Dharma type means that the lower sealing expansion portion 13 has a semicircular shape and the upper connecting pipe 3 has a semicircular diameter and both semicircular diameters. It is a shape like the outer shape of a snowman in which the left and right side surfaces of the irregularly shaped portion 31a of the connecting pipe 3 connecting the two are continuous.

After the connecting pipe 3 is inserted into the end portion 2b of the outer pipe 2, the gap formed between the connecting terminal 31 and the sealing expansion portion 13 and the inner surface of the mating connecting portion 21 is brazed to the gap. Prevents the leakage of the fluid, and firmly fixes the outer pipe 2, the inner pipe 1, and the connecting pipe 3.

Further, the fluid guiding portion 22 surrounds the swirling flow paths 51a, 51b, and 51c, and as shown in FIGS. 1 and 2, each swivel between the end port 3b of the connecting pipe 3 and the top portion 11a of the uneven portion 11. A guide passage 53 for flowing a fluid is formed between the flow paths 51a, 51b, and 51c.
The guide passage 53 guides the fluid from the end port 3b of the connecting pipe 3 to the swirling passages 51a, 51b, 51c between the uneven portions 11 on the inlet side, and is uneven on the outlet side, contrary to the inlet side. It guides the swirling flow paths 51a, 51b, 51c between the portions 11 to the end port 3b of the connecting pipe 3.

The fluid guide portion 22 is in contact with the slave wall portion 23 in which the guide passage 53 extends inward in the axial direction from the fitting connection portion 21 and the top portion 11a of the uneven portion 11 of the inner pipe 1 from the slave wall portion 23. It is composed of a main wall portion 24 whose diameter gradually decreases in a tapered shape.
Then, as shown in FIG. 2, the base end of the main wall portion 24 connected to the secondary wall portion 23 has a maximum diameter α, and in the vicinity of the maximum diameter portion 24a, a curved surface in which peripheral wall surfaces are gently continuous on both sides in the axial direction. It is formed so as to be.

As shown in FIG. 4, the secondary wall portion 23 is circular when the raw pipe is once expanded into a conical tubular bottom-side shape and the fitting connection portion 21 of the end portion 2b is deformed into a Dharma shape. It is formed on a curved surface that transitions until the portion is pressurized and becomes a Dharma shape.
At that time, since the left and right sides of the end port 2c side of the outer pipe 2 are depressed, the area inside the wall surface is reduced toward the fitting connection portion 21, and the portion that remains circular without being depressed is connected to the main wall portion 24 next. It becomes the maximum diameter portion 24a of the base end of.
That is, the left and right cross-sectional areas of the lower half of the narrowed portion 26 decrease toward the sealing expansion portion 13, and the left and right cross-sectional areas of the upper half of the narrowed portion 27 decrease toward the end port 31b of the connection terminal 31.

As shown in FIG. 1, the end port 3b of the connecting pipe 3 facing the secondary wall portion 23 is arranged so as to be slightly retracted from the inner side wall of the sealing expansion portion 13 so as not to protrude into the guide passage 53. By doing so, when the fluid circulates here, it can smoothly circulate to the guide passage 53 without generating a large turbulent flow at the pipe mouth portion of the connecting pipe 3.

As shown in FIG. 4, the main wall portion 24 has a base end having a maximum diameter α and is connected to the slave wall portion 23, and the end is tapered in a tapered shape to form the top of the uneven portion 11 of the inner pipe 1. The minimum diameter β is the same as the circle in contact with 11a.
The main wall portion 24 is inclined so that the center line of the tapered pipe is inclined toward the upper connecting pipe 3 side, so that the maximum diameter portion 24a shown in the circular cross section of FIG. The upper side of the passage 53 near the connecting pipe 3 is wide, and the lower side away from the connecting pipe 3 is narrow.
Further, even in the intermediate portion of the main wall portion 24, as shown in FIG. 6 (c), a guide passage 53 having a small diameter but a wide upper side and a narrow lower side is formed between the inner pipe 1 and the uneven portion 11. Will be done.

In the first example, as shown in FIG. 6B, the inner wall 28 on the side of the expanding portion for sealing on the lower side of the main wall portion 24 is in contact with the top portion 11a of the uneven portion 11 of the inner pipe 1 at the lowermost portion. Therefore, there is no difference between the distance L of the wall surface of the main wall portion 24 from the center P of the inner pipe 1 and the radius R of the inner pipe 1.
Then, the difference between the distance L of the wall surface of the main wall portion 24 from the center P of the inner pipe 1 and the radius R of the inner pipe 1 from the lowermost portion of the inner wall 28 on the expansion portion side for sealing to the upper left and right sides. Becomes larger. Then, on the uppermost side, the difference in distance between the two becomes maximum.
Therefore, the fluid guiding portion 22 has a maximum diameter α at a close position in front of the end port 3 of the connecting pipe 3 into which the fluid directly flows, and the difference in the distances is maximized, and the connecting pipe 3 is in the widened space. The required flow rate can be smoothly distributed according to the size of the diameter.
Then, the end port 52c of the swirling flow path of the swirling flow path 51c farthest downward from the end port 3b of the connecting pipe 33 narrows as it goes downward from the end port 52c of the swirling flow path, but the flow of the swirling flow path 51c. Since the middle of the road turns to the left and right and continues to the space in the open circle on the left and right, even if the end 52c portion of the swirling flow path of the lower swivel flow path 51c is blocked by the sealing expansion portion 13. There is no dead space where the flow is stagnant, and the fluid can flow up to the end 52c of the swirling flow path.

Further, in the axial direction, the difference between the distance L of the wall surface of the main wall portion 24 and the radius R of the inner pipe 1 gradually decreases from the maximum diameter portion 24a toward the end, and the minimum diameter portion 24b at the end thereof. The diameter is the same as the circle in contact with the top portion 11a of the uneven portion 11 from the center P of the inner pipe 1, and there is no difference in the distance as shown in (2) of FIG.
Then, over the entire length of the main wall portion 24, the fluid is narrowed down to the tapered wall surface from the wide left and right guidance passages of the maximum diameter portion 24a in the lower swirling passages 51b and 51c facing the guidance passage 53. It is guided by and distributed.

In the above-mentioned Patent Document 1, a complicated direction change occurs by hitting the tip of the distribution guide portion or refracting diagonally to generate turbulent flow in various places. On the other hand, in the present invention, the guide passage 53 The fluid guiding unit 22 surrounds the entire circumference of the swirling flow path in a substantially circular shape until the fluid flows in from the wide connecting pipe side and flows out to the swirling flow path between the uneven portions, and the fluid guides the wide left and right sides of the maximum diameter portion 24a. It is converged so as to be narrowed down by a tapered wall surface in which the gap gradually decreases from the passage, and during that time, it can be smoothly circulated with almost no turbulence.

Then, in order to prevent the space on the left and right of the guiding passage 53 from becoming excessively narrow, the fluid guiding portion 22 uses the maximum diameter portion 24a as the circumscribed circle of the top portion 11a of the uneven portion 11 of the inner pipe 1 and a plurality of swirling flow paths. It is a substantially circular shape having a cross-sectional area larger than the total cross-sectional area of 51.
Therefore, a certain volume required for smooth flow of the fluid is maintained in the guide passage 53 inside the secondary wall portion 23 and the main wall portion 24.
The lower side of the guide passage 53 in the main wall portion 24 gradually narrows as it goes down, but the axial portion of the inner wall of the main wall portion 24 is aligned with the top portion 11a of each uneven portion 11 of the inner pipe 2. Even if it is in contact with the connecting pipe 3, the fluid in front of the connecting pipe 3 is supplied to the lower side through the space on the left and right of the circularly bulging guide passage 53 from the wide upper side, and the guide passage for receiving the fluid. Since the swirling flow path 51 that opens facing the 53 spirally swirls and opens diagonally from the bottom to the upper left and right spaces, the lower side requires a smaller inflow amount than the upper side, and is guided. The passage 53 can be made narrower.
In this way, the guide passage 53 is formed so that the upper connecting pipe 3 side, which requires a large flow rate, is wider and the side far from the lower connecting pipe 3 requiring a small flow rate is gradually narrowed. It is possible to make the outer diameter of the joint portion smaller and more compact. Then, it is possible to increase the degree of freedom in the layout of the assembly at the place of use.

For example, if the diameter of the maximum diameter α portion, which is the maximum diameter portion 24a, of the main wall portion 24 is 22 mm, the circular cross-sectional area thereof is about 414 mm ² .
Since the cross-sectional area of the outer diameter of the inner pipe having the uneven portion 11 is 238 mm ² , a guide passage 53 having a cross-sectional area of 176 mm ² is formed at the maximum diameter α portion.
This cross-sectional area is about 6 times the total cross-sectional area of each swirling flow path 51a, 51b, 51c between each uneven portion with respect to 28 mm ² , and is sufficient for smooth flow of fluid. is there.
In FIG. 3, the outline of the main wall portion 24 is substantially circular, but the substantially circular shape includes a perfect circle, an ellipse, an oval, and the like that are close to a circle.

Further, as shown in FIG. 3, the portion having the maximum diameter α, which is the boundary between the secondary wall portion 23 and the main wall portion 24, has a diameter smaller than the total value of the outer diameters of the sealing expansion portion 13 and the connecting pipe 3. If so, the outer diameter can be made compact by fitting all of the outer pipe 2 and the connecting pipe 3 in a circular shape that is in contact with the outer circumference, and the degree of freedom in layout is increased so that the piping at the place of use can be used in severe situations. It becomes possible to increase.

In the vicinity of the minimum diameter portion 24b at the end of the main wall portion 24 of the fluid guiding portion 22, the guiding passage 53 gradually narrows. Therefore, when the minimum diameter portion 24b is close to the fitting connection portion 21, the main wall portion 24 is excessively short, and the volume of the guide passage 53 formed inside is excessively small, a part of the swirling flow flows. The flow path connected to the path 51c becomes extremely narrow, and it becomes difficult for the fluid to flow in the swirling flow path 51c, which is not preferable.
For example, when the width of the uneven portion 11 is 9 mm and the axial length of the fluid guiding portion 22 is shortened to about 4 mm, the horizontal cross-sectional area becomes extremely small even if the round-cut cross-sectional area of that portion is large. The guide passage 53 is flattened in the vertical direction and the volume of this portion becomes excessively small, and the wall surface of the main wall portion 24 is steeply inclined so that the fluid traveling straight through the connecting pipe 3 becomes the steeply inclined wall. At the end, a sudden change in the direction of flow hinders smooth flow, which is not preferable.
Further, when the minimum diameter portion 24b at the end of the main wall portion is far away from the fitting connection portion 21 and the guided passage 53 formed is unnecessarily long, the fluid flow is not obstructed, but the processing range is wide. Not only is it difficult, but the range that can be bent when laying out becomes narrower as the distance from the fitting connection portion 21 increases, and a long lateral gap is formed between the top portion 11a of the uneven portion 11 and the outer pipe 2. This is not preferable because the independence of each swirling flow path is impaired and the heat exchange efficiency is lowered.
That is, even if the length of the main wall portion 24 in the axial direction is short, the flowability is sufficient, so that it is not necessary to lengthen it unnecessarily, and the length of the fitting connection portion 21 is spirally uneven from the fitting connection portion 21. It is preferable that the range exceeds at least one and does not exceed three.

The position of the minimum diameter portion 24b of the main wall portion 24 is, for example, when each portion has three uneven portions 11 at 38 pitches as in the above example, the position of the minimum diameter portion α portion of the guide passage 53 is as described above. is the cross-sectional area of 176 mm ^2, each swirl channel 51a, 51b, the total 28mm ² cross-sectional area of 51c, the cross-sectional area of the guide channel 53 in the intermediate portion of the main wall portion 24, half of the maximum aperture α portion It becomes about 88 mm ² . Therefore, the position of the minimum diameter portion 24b of the main wall portion 24 is 9 mm to 27 mm, which is a numerical value when at least one spiral uneven portion 11 is exceeded from the fitting connection portion 21 and when not exceeding three. It can be extremely short.
FIG. 1 of the first example shows an embodiment in which the minimum diameter portion 24b at the end of the main wall portion 24 does not exceed two of the fitting connection portion 21 and the uneven portion 11, and the length of the main wall portion 24 is longer than this. In FIG. 7 of the second example, the position of the minimum diameter portion 24b at the end of the main wall portion of the main wall portion 24 is such that the position of the minimum diameter portion 24b exceeds one of the uneven portions 11 from the fitting connection portion 21. ing.
In this way, the position of the minimum diameter portion 24b, which is the minimum diameter β of the main wall portion 24, is such that the fluid is guided from the end port 3b of the connecting pipe 3 to the swirling flow paths 51a, 51b, 51c forming the heat exchange passage 5. It can be adjusted and determined so that the position can be smoothly distributed without excess or deficiency via 53.

The fluid can swirl in the swirling flow path 51 between the spiral concavo-convex portions 11 in the main wall portion 24, and the swirling flow path 51 between the concavo-convex portions 11 is widely wide in the circumferential direction on the maximum diameter portion 24a side. It faces the space in the guide passage 53, and the space becomes narrower on the side of the minimum diameter portion 24b at the end.
The guide passage 53 has the maximum cross-sectional area at the maximum diameter portion 24a, but the main wall portion 24 is not unnecessarily long because there is a margin in the capacity of the fluid there.
Further, even if the narrow end portion is short in the axial direction, the fluid flows through all of the swirling flow paths 51a, 51b, and 51c, so that the position of the minimum diameter portion 24b has the same width between the top portions 11a of the uneven portion 11. If there is, it does not change even if the number of uneven portions is 3 or more.

In this respect, in the above-mentioned Patent Document 1 which is the object of improvement of the present invention, it is necessary to increase the length of the tubular distribution guide portion so as to reach each uneven portion as the number of uneven portions increases. In the present invention, this is not necessary, and by expanding the diameter of the base end of the tapered main wall portion 24 to the maximum circular shape, smooth flowability to all the plurality of swirling flow paths 51 is ensured. Therefore, contrary to the above-mentioned Patent Document 1, it is possible to shorten the axial length of the joint portion.
And, for example, in the use of automobile air conditioners, the design of heat exchange piping is usually a lower priority than other devices, and it is narrow and complicated left after the layout of various devices such as engines is decided. Piping routes are often determined in various spaces, so double pipes for heat exchange may not fit unless they are bent to the limit of a few millimeters.
In such a situation, in the present invention, the bendable range is widened by shortening the fluid guide portion 22 of the joint portion that cannot be bent, and the outer diameter of the joint portion is reduced to provide a limited space. It is possible to have a layout that can be used in a variety of ways.

In the fluid in the fluid guiding portion 22, the flow in the inlet direction and the flow in the outlet direction flow in opposite directions.
In the inlet direction, as shown in FIGS. 1 and 2, on the upper side, the fluid travels in the axial direction from the connection pipe 3 end port 3b, and all swirling flows from the minimum diameter portion 24b at the end so as to be throttled by the main wall portion 24. It will proceed in the road 51. On the other hand, on the lower side, as shown by the arrows (b) and (c) in FIG. 6, the fluid entering from the connection pipe 3 end port 3b divides the guide passage 53 into left and right, which gradually narrows toward the lower side. It wraps around to the lower side, divides into each swirling flow path 51b and 51c, and gradually converges.
As a result, as shown in FIG. 6 (2), all of the swirling passages 51a, 51b, and 51c smoothly flow out through the guidance passage 53.
In the outlet direction, the fluid traveling while swirling each swirling flow path 51 between the spiral concavo-convex portions 11 flows out into the induction passage 53 opened facing the swirling flow paths 51a, 51b, 51c. ..
Further, the guide passage 53 extending in the circumferential direction is advanced toward the end port 3b of the connecting pipe 3 while turning the wall portion 24, and is guided to the gradually closing surface of the slave wall portion 23 to the end opening 3b of the connecting pipe 3. It is converged and goes out.
Therefore, it can be smoothly distributed in both the inlet and outlet directions.

The above is the first example of the present invention, and next, a second example which is a form different from the first example will be described.
7 to 9 show a second example.
In the second example, the basic joint structure is the same as in the first example, but in the first example, the end portion 11b of the spiral uneven portion 11 of the inner pipe 1 is in contact with the sealing expansion portion 13. However, in the second example, as shown in FIGS. 7 and 8, the sealing expansion portion 13 of the inner pipe 1 and the end portion 11b of the uneven portion 11 are slightly separated from each other. An annular groove 4 in which the groove bottom is connected to the bottom surface of the recess 12 of the uneven portion 11 is formed in the separated portion, and an annular space 55 forming a part of the guide passage 53 is formed inside the annular groove 4. ..
In the second example, as shown in FIGS. 7 and 9 (b), the top 11a of the uneven portion 11 of the inner pipe 2 is aligned in the axial direction on the inner wall of the main wall portion 24 of the outer pipe 2. This point is the same as that of the first example.

As shown in FIGS. 7 and 8, the bottom of the annular groove 4 and the bottom of the recess 12 between the spiral concave-convex portion 11 are connected without a step as the wall surface of the raw pipe. Therefore, the end port 52 of the swirling flow path between the end portions 11b of the uneven portion 11 comes into contact with the groove bottom of the annular groove 4, and the fluid flow path is directly connected from the annular space 55 into the guide passage 53 as it is.

As the groove width of the annular groove 4 is increased, the capacity of the annular space 55 in the annular groove 4 increases, and the fluid easily flows.
However, since the groove bottom of the annular groove 4 is flat, the larger the groove width, the lower the strength of the pipe wall against the pressure from the fluid, and the more easily it is deformed or crushed. If it is deformed, the passage of the fluid in the inner pipe 1 is narrowed, which makes it difficult for the fluid to flow.
Therefore, in the present invention, it is preferable that the annular groove 4 has an extremely narrow width, and the groove width is narrower than the groove width between one uneven portion 11 of the inner pipe 1 at the maximum. With such a narrow groove width, the end portion 11b of the uneven portion 11 and the side portion of the sealing expansion portion 13 approach each other and rise to both sides of the annular groove 4, and the rising surface acts like a rib structure to form a groove. The strength of the bottom does not decrease.
For example, when the width of the bottom of the concave portion 12 between the uneven portions 11 is 4 mm, the groove bottom width of the annular groove 4 is up to about 4 mm, the height of the uneven portion 11 is 2 mm, and the height of the expansion portion 13 for sealing is set. When is 2 mm, the annular groove 4 is reinforced by the rising wall surfaces of 2 mm formed on both sides.

The reason for providing such an annular groove 4 is to shorten the main wall portion 24 so that the degree of freedom in the layout of the double pipe is further increased.
The end port 52c of the swirling flow path that opens downward facing the guide passage 53 tends to be inferior in flowability because the guide passage 53 is narrower than the end port 52a of the swirl flow path that opens upward. Therefore, in order to shorten the length of the main wall portion 24, it is effective to improve the flowability toward the end port 52c of the swirling flow path that opens downward, which is inferior in flowability.
In the second example, as shown by the arrows in (a) and (b) of FIG. 9, the fluid descends from the connecting pipe 3 side to the lower side of the annular space 55 in the annular groove 4, and the fluid wraps around. Passes from the annular space 55 through the end port 52c of the lower swirling flow path 51c, and a considerable flow rate flows into the swirling flow path 51c.
If the flow rate to the lower swirl flow path 51c flowing through the annular space 55 and the amount flowing into the swirl flow path from the upper top 11a side of the uneven portion 11 facing the guide passage 53 are totaled, all swivel. A larger flow rate of fluid can flow through the flow paths 51a, 51b, 51c.

For example, in the first example, if there is no annular groove 4 and the end of the main wall portion 24 is located at a position about 15 mm away from the fitting connection portion 21, a third example can obtain the same level of distribution performance. In the example, when the groove width of the annular groove 4 is 4 mm, which is the same as the bottom width of the recess 12 of the concave-convex portion 11, the minimum diameter portion 24b at the end of the main wall portion 24 is swirled from the fitting connection portion 21. It is possible to shorten the position to about 9 mm, which is separated by the width of the road 51.

Next, a third example, which is a form different from the first and second examples, will be described.
10 to 12 show a third example.
In the third example, as shown in FIG. 10, the pipe diameter is tapered so that the lower inner wall between the maximum diameter portion 24a and the minimum diameter portion 24b of the main wall portion 24 is separated from the top portion 11a of the uneven portion 11. An expansion portion 25 is formed by expanding to the lower side, and an expansion space 55 forming a part of the guide passage 53 is formed inside the expansion portion 25.
The open space 54 allows the fluid to flow by increasing the flow rate between the inner wall of the main wall portion 24 and the top portion 11a of the uneven portion 11 of the inner pipe 1.
In the first and second examples, the top 11a of the uneven portion 11 of the inner pipe 1 is in contact with the lower wall surface of the main wall portion 24 so as to be aligned in the axial direction. Although different from the first and second examples, the other basic joint structure is the same as that of the first example.

Further, in the first example, since the space becomes narrower as the guide passage 53 goes downward, the amount of flow over the top 11a of the uneven portion 11 decreases, and the lowermost side is the lower side of the main wall portion 24. When the wall surface comes into contact with the top portion 11a of the uneven portion 11, the gap in the guide passage 53 is almost eliminated.
However, since the swirling flow path 51c itself between the tops 11a of the uneven portion 11 communicates diagonally with both sides of the contact portion without reducing the cross-sectional area of the flow path at all, the fluid of the swirling flow path 51c sufficiently flows. Can be made to.
In the third example, an enlarged portion 25 is provided by expanding the lower portion of the guide passage 53. As a result, the fluid can flow from the lowest side in the main wall portion 24 beyond the top portion 11a of the uneven portion 11 into the open space 54.
In this third example, since a large amount of fluid can flow from the open expansion space 54 formed under the guide passage 53, the main wall portion 24 is larger than the first example depending on the size of the expansion of the expansion portion 25. It is possible to shorten the axial length of.
Then, by making the entire joint portion shorter, it is possible to increase the degree of freedom in the layout of the double pipe assembly.
As shown in (a) and (b) of FIG. 12, the cross section of the guide passage 53 having the expansion space 54 in the expansion portion 25 is basically circular in total length, but the lower side is Since it is expanded, it can be a circle that is not a perfect circle, such as an ellipse that is close to a circle or an oval.

The enlarged portion 25 is provided with an open / expanded space 54 on the lower side of the main wall portion 24 so that the lower swirling flow path 51c and the fluid can easily flow, and as shown in FIG. 11, the enlarged portion 25 of the enlarged portion 25. The range is about the lower half.
The height from the expanding inner pipe 1 is sufficient at a small distance equal to or less than the height from the recess 12 to the top 11a of the uneven portion 11 where the cross-sectional area of the lower swirl flow path 51c can be obtained. .. At this height, the cross-sectional area of the guide passage 53 having the expansion space 54 in the expansion portion 25 is larger than the total cross-sectional area of the swirling passages 51b and 51c, so that sufficient fluid flowability can be ensured.

In the third example, as shown in (a) of FIG. 12, both ends of the expansion base end portion 25a and the expansion end portion 25b on both sides of the expansion portion 25 gently incline the stepped portion due to expansion to generate turbulence. Make it difficult.
As a result, the flowability of the lower fluid is improved, and the length of the main wall portion 24 can be further shortened as compared with the first example.
Even if the diameter of the joint increases slightly downward due to the expansion of the diameter, the increase in the diameter is extremely small, so there is almost no effect on the degree of freedom in layout in the radial direction, and the joint portion is the axis. By shortening the length depending on the direction, it is possible to further expand the degree of freedom in the assembly layout of the double pipe.
For example, the height of the uneven portion 11 is 2 mm, and the width of the expansion space 54 is the same 2 mm. Assuming that the diameter of the maximum diameter portion 24a of the main wall portion 24 is 22 mm in the first example, in this third example, the maximum diameter portion 24a is expanded downward by 2 mm and slightly expanded to 24 mm. Assuming that the distance from the fitting connection portion 21 to the end of the main wall portion 24 is 15 mm in the first example, in this third example, the distance from the fitting connection portion 21 by the width of one swirling flow path 51 is about 9 mm. It is possible to shorten it to the position of.

INDUSTRIAL APPLICABILITY The present invention can be used as a heat exchanger for various heat exchangers for home and industrial use, in addition to the heat exchanger for an automobile air conditioner.

1 Inner pipe 1a Outer wall 11 Concavo-convex part 11a Top 11b End part 12 Recessed part 13 Inflatable part for sealing 2 Outer pipe 2a Inner wall 2b End part 2c End mouth 21 Fitting connection part 22 Fluid guidance part 23 Sub-wall part 24 Main wall part 24a Maximum diameter Part 24b Minimum diameter part 25 Enlarged part 25a Enlarged base end part 25b Enlarged end part 26 Squeezed part 27 Squeezed part 28 Inner wall on the expansion part side for sealing 3 Connection pipe 3a End 3b End mouth 31 Connection terminal 31a Deformed part 31b Concave part 4 Circular groove 5 Heat exchange passage 51 Swirling flow path 51a, 51b, 51c Swirling flow path 52 Swirling flow path end port 52a, 52b, 52c Swirling flow path end port 53 Guide passage 54 Opening space 55 Circular space 6 Wax material a Connection pipe Axial direction of the end b Axial direction of the double pipe α Maximum diameter β Minimum diameter P Center of the inner pipe R Radius of the circle in contact with the top of the uneven part of the inner pipe L Distance from the center of the inner pipe of the wall surface of the fluid guide

Claims (4)

For a double pipe for a heat exchanger in which a heat exchange passage is formed between an inner pipe and an outer pipe having a plurality of spiral uneven portions, an inlet and an outlet of a fluid flowing through the heat exchange passage are used. In the joint structure of the double pipe connecting the connecting pipes
The inner pipe is provided with a sealing expansion portion in which the facing portion of the inner wall of the outer pipe end portion is bulged in an annular shape, and the uneven portion is provided with the end portion approaching the sealing expansion portion. The connecting pipe is provided with a substantially D-shaped irregularly shaped connecting terminal surrounded by the inner shape of the outer pipe end and the outer shape of the sealing expansion portion of the inner pipe at the end thereof.
The outer pipe has a Dharma-shaped fitting connection portion that surrounds the connection terminal of the connection pipe and the expansion portion for sealing of the inner pipe, and the end opening of the connection pipe and the uneven portion of the inner pipe. A fluid guiding portion is provided so as to cover the outside of the end portion and form a guiding passage for guiding the fluid from the end opening of the connecting pipe to each swirling flow path formed between the uneven portions.
The maximum diameter portion of the fluid guide portion is a substantially circular shape having a cross-sectional area larger than the sum of the circumscribed circle at the top of the uneven portion of the inner pipe and the cross-sectional area of a plurality of swirling flow paths, and from the center of the inner pipe. A guide passage is formed by surrounding each swirl flow path so that the difference in distance between the wall surface of the inner pipe and the wall surface of the outer pipe gradually increases toward the connecting pipe, and the outside of the fluid guide portion is on one side from the maximum diameter portion. A double pipe joint structure characterized in that a tapered main wall part connected to the outer pipe of the pipe is arranged, and a secondary wall part connected to the connecting pipe is arranged on the other side. The maximum diameter of the main wall is a double pipe joint structure that is smaller than the total diameter of the expansion part for sealing and the outer diameter of the connecting pipe. A double pipe joint structure characterized in that the end of the uneven portion of the inner pipe and the expansion portion for sealing are brought close to each other through an annular groove. A double pipe joint structure characterized by enlarging the diameter of the inner wall of the main wall near the uneven part of the inner pipe.

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