JP2005172196A - Double pipe and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double pipe easy to manufacture for preventing the generation of chattering noises by putting an outer pipe in strong contact with an inner pipe, independently of bending curvature. <P>SOLUTION: The double pipe comprises the outer pipe 1 for first fluid to flow and the inner pipe 2 arranged therein for second fluid to flow. In the state that the inner pipe 2 is inserted into the outer pipe 1, the pipe wall of the outer pipe 1 is crushed to be flat from two directions across the pipe, thereby putting the inner pipe 2 in pressure contact therewith. Outer pipe crushing places 20 are located in the longitudinal direction of the outer pipe 1 in spaced relation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a double pipe used for a refrigerant pipe of a vehicle air conditioner and a manufacturing method thereof.

  As a piping member for circulating the refrigerant, an attempt has been made to use a double pipe in which an inner pipe is provided inside the outer pipe so that a double flow path can be obtained.

  When such a double pipe is used, the piping members can be routed simply and compactly. This is especially true when the piping layout is greatly limited by the structure of the vehicle body or the like, such as a vehicle air conditioner. It is advantageous. Further, by using the double pipe, the assembling work of the air conditioner is also simplified, and the manufacturing cost can be reduced.

  As shown in FIG. 2, a conventional double pipe includes an inner pipe 2 for flowing a second fluid inside an outer pipe 1 for flowing a first fluid, and between the outer pipe 1 and the inner pipe 2. The thing of the structure which connected both the pipes 1 and 2 by providing the connection rib 3 is known (for example, refer patent document 1).

Such a double tube is generally manufactured by integrally forming the outer tube 1, the inner tube 2, and the connecting rib 3 by extrusion or drawing from an aluminum material.
JP-A-2001-341027

  However, since the double pipe provided with the conventional connecting rib 3 needs to be manufactured by extrusion or drawing, the cost is high. Further, when processing the pipe end, a cutting process of the connecting rib 3 is necessary, and there is a problem that the number of man-hours during the piping work increases.

  Therefore, it is conceivable to construct a double pipe by inserting a small-diameter inner pipe into a large-diameter outer pipe later. If so, the outer pipe and the inner pipe can be manufactured as independent pipes, which reduces the cost. However, if the inner tube is simply inserted into the outer tube, no matter how firmly the ends of the outer tube and inner tube are fixed, if the inner tube and outer tube come into contact with each other, There may be a chatter noise.

  For example, as shown in FIG. 3, when the double pipe is bent into a shape corresponding to the required piping layout in a state where the inner pipe 2 is inserted into the outer pipe 1, the inner pipe 2 and the outer pipe 1 are in contact with each other. A, B, C, and D are generated, and chatter noise may be generated due to vehicle vibrations at that location. In particular, when the length of the pipe is long, a portion E in which the inner tube 2 sags in the outer tube 1 is generated, and thus a large chatter noise may occur at the contact point C in the sag portion E.

  In order to solve this problem, as shown in FIG. 4, if the curvature of bending is reduced (that is, tight bending) and the inner tube 2 strongly hits the inner wall of the outer tube 1 at the contact points A and B, the chatter sound Can be suppressed. However, not all parts are necessarily bent with a small curvature, and if there is a loosely bent part as shown in FIG. 5, the contact part A becomes weak and the occurrence of chatter noise is inevitable. there is a possibility.

  In consideration of the above circumstances, the present invention is capable of strengthening the contact between the outer tube and the inner tube regardless of the curvature of bending, and a double tube that can be easily manufactured and capable of preventing the chatter noise. An object is to provide a manufacturing method.

  The double pipe of the invention of claim 1 is a double pipe in which an inner pipe for flowing a second fluid is disposed inside an outer pipe for flowing a first fluid, and the inner pipe is inserted into the outer pipe. The tube wall of the outer tube is crushed inward to be brought into pressure contact with the inner tube.

  A double pipe according to a second aspect of the present invention is the double pipe according to the first aspect, wherein the wall of the outer pipe is brought into pressure contact with the inner pipe by flattening from two directions sandwiching the pipe. It is characterized by that.

  A double pipe according to a third aspect of the present invention is the double pipe according to the first or second aspect, wherein the crushed portions of the outer pipe are arranged at intervals in the length direction of the outer pipe. To do.

  According to a fourth aspect of the present invention, there is provided a double pipe manufacturing method in which an inner pipe for flowing a second fluid is disposed inside an outer pipe for flowing a first fluid. A tube is inserted, and the tube wall of the outer tube is crushed inward to be brought into pressure contact with the inner tube.

  According to a fifth aspect of the present invention, there is provided a double pipe manufacturing method in which an inner pipe for flowing a second fluid is disposed inside an outer pipe for flowing a first fluid, wherein the inner pipe is disposed inside the outer pipe. Inserting the tube, bending the outer tube and the inner tube along the length direction at a predetermined location in that state, and then pressing the inner wall into the inner tube by crushing the tube wall of the outer tube Features.

  According to a sixth aspect of the present invention, there is provided a double pipe manufacturing method in which an inner pipe through which a second fluid flows is disposed inside an outer pipe through which a first fluid flows. After the tube is inserted and the end treatment of the outer tube and the inner tube is performed in that state, both the outer tube and the inner tube are bent along the length direction at predetermined locations, and then the tube wall of the outer tube is It is characterized in that it is pressed against the inner tube by crushing inward.

  The manufacturing method of the double pipe of the invention of claim 7 is the manufacturing method of the double pipe according to any one of claims 4 to 6, wherein the pipe wall of the outer pipe is sandwiched between two directions. It is characterized in that it is pressed against the inner tube by crushing it flat.

  The manufacturing method of the double pipe of the invention of claim 8 is the manufacturing method of the double pipe according to any one of claims 4 to 6, wherein the crushed portion of the outer pipe is set to the length of the outer pipe. It is characterized by being arranged at intervals in the direction.

  According to the invention of claim 1, since the inner tube is inserted into the outer tube, the outer tube is crushed inward so that the inner tube is pressed against the inner tube, so that the outer tube is gently bent. Even in such a place, the inner tube and the outer tube can be securely pressed against each other, and chatter noise during vehicle vibration can be effectively prevented.

  According to the invention of claim 2, since the tube wall of the outer tube is flattened from two directions sandwiching the tube and pressed against the inner tube, a simple method of crushing the outer tube with a pair of pressing members is used. The inner and outer tubes can be fixed.

  According to invention of Claim 3, since the crushing location of the outer tube was arrange | positioned at intervals in the length direction of the outer tube, compared with the case where the full length is crushed, processing becomes easy.

  According to the invention of claim 4, since the inner tube is inserted inside the outer tube, the outer tube is crushed inward so that it is pressed against the inner tube, so that the outer tube is gently bent. Even in such a place, the inner tube and the outer tube can be securely pressed against each other, and chatter noise during vehicle vibration can be effectively prevented.

  According to invention of Claim 5, since a bending process is performed before the crushing process of an outer tube | pipe, a bending process can be performed with sufficient workability | operativity, without minding a crushing part.

  According to the invention of claim 6, since the end treatment of the outer tube and the inner tube is performed before the bending process and the crushing process of the outer pipe, the bending process is performed with good workability without worrying about the bent part and the crushing part. be able to.

  According to the seventh aspect of the present invention, since the tube wall of the outer tube is flattened from two directions sandwiching the tube and pressed against the inner tube, a simple method of crushing the outer tube with a pair of pressing members is used. The inner and outer tubes can be fixed.

  According to the invention of claim 8, since the crushed portions of the outer tube are arranged at intervals in the length direction of the outer tube, the processing is simpler than the case where the entire length is crushed. In addition, when bending the double pipe after crushing the outer pipe, the inner pipe and the outer pipe are already in strong pressure contact at the part where the outer pipe is crushed, so there is no concern about the generation of chatter noise. It can be bent freely with any curvature. In addition, the portion where the outer tube is crushed has a weak bending rigidity in the crushing direction due to the relation of the section modulus. Therefore, bending at the portion facilitates bending.

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

  FIG. 1 is an explanatory view of a double tube and a method for manufacturing the same according to an embodiment of the present invention. As shown in FIGS. 1C, 1D, and 1E, this double pipe is provided with an inner pipe 2 for flowing a second fluid inside an outer pipe 1 for flowing a first fluid. The outer tube 1 and the inner tube 2 have a structure without a connecting rib that keeps the gap between them constant.

  In order to obtain the double pipe shown in FIGS. 1 (c), (d), (e), first, as shown in FIG. 1 (a), a small diameter inner pipe 2 and a large diameter are used as independent pipes each having a circular cross section. The outer tube 1 is prepared, and the inner tube 2 is inserted into the outer tube 1 as shown in FIG. In this state, the tube wall of the outer tube 1 is flattened by applying force as indicated by an arrow F from two directions sandwiching the tube at predetermined locations set at intervals in the length direction. c) As shown in (d) and (e), the tube wall of the outer tube 1 is brought into pressure contact with the inner tube 2. In this way, the outer tube 1 and the inner tube 2 can be crushed and fixed at the crushing location 20 while ensuring a continuous flow path between the outer tube 1 and the inner tube 2 over the entire length. Here, as a method of crushing the outer tube 1 from two directions, a simple method of crushing the outer tube 1 with a pair of pressing members (not shown) can be employed. Although the crushing direction is not limited to two directions, it can be said that crushing in two directions is the easiest to work.

  In this way, the inner tube 2 and the outer tube 1 can be surely secured even in a place where the outer tube 1 is gently bent by crushing the tube wall of the outer tube 1 inward and press-contacting it with the inner tube 2. Can be strongly pressed against each other, and chatter noise can be effectively prevented during vehicle vibrations. Further, the inner tube 2 and the outer tube 1 can be combined after being manufactured as independent tubes, and since there is no need to provide an extra connecting rib between the inner tube 2 and the outer tube 1, the manufacturing is easy. Moreover, it does not take time and effort to process the pipe end.

  In addition, by arranging the crushing portions 20 of the outer tube 1 at intervals in the length direction of the outer tube 1, the processing becomes easier compared to the case of crushing the entire length. In this case, since the portion where the outer tube 1 is not crushed remains as a circular tube, the existing circular tube support mechanism can be used as it is for supporting the completed double tube. Further, since the inner tube 2 and the outer tube 1 are already in strong contact with each other at the portion where the outer tube 1 is crushed, it can be freely bent with an arbitrary curvature without worrying about the occurrence of chatter noise. . Further, the portion 20 where the outer tube 1 is crushed has a weak bending rigidity in the crushing direction due to the relation of the section modulus. Therefore, bending at the portion makes it easier to bend.

  In addition, when bending a completed double pipe along a length direction in this way, it is good to crush the outer pipe | tube 1 after bending first beforehand. That is, the inner tube 2 is inserted into the outer tube 1, and in this state, both the outer tube 1 and the inner tube 2 are bent along the length direction at predetermined locations, and then the tube wall of the outer tube 1 is moved into the inner tube. It is better to press the inner tube 2 by crushing in the direction. This is because bending can be performed with good workability without worrying about the crushed portion.

  Similarly, terminal processing should be performed first. That is, with the inner tube 2 inserted into the outer tube 1, the terminal treatment of the outer tube 1 and the inner tube 2 is performed first, and then both the outer tube 1 and the inner tube 2 are moved in the longitudinal direction at predetermined locations. It is preferable that the inner tube 2 and the outer tube 1 are fixed by bending along the outer tube 1 and then crushing the outer tube 1. This is because the bending process can be performed with good workability without worrying about the bent part or the crushed part.

It is sectional drawing used for description of the double tube and manufacturing method of embodiment of this invention, (a)-(c) is each process drawing, (d) is an Id-Id arrow view of (c), (e). FIG. 6 is a cross-sectional view taken along the line Id-Id of (c). It is a perspective view which shows the structure of the conventional double tube. It is explanatory drawing of the problem at the time of inserting an inner tube | pipe simply in the inside of an outer tube | pipe. It is explanatory drawing of the problem at the time of inserting an inner tube in the inside of an outer tube, and bending the outer tube tightly. It is explanatory drawing of the problem at the time of inserting an inner pipe | tube in an outer pipe | tube and bending an outer pipe | tube loosely.

Explanation of symbols

1 Outer tube 2 Inner tube 20 Crushing location

Claims (8)

In the double pipe in which the inner pipe (2) for flowing the second fluid is disposed inside the outer pipe (1) for flowing the first fluid,
The inner tube (2) is inserted into the outer tube (1) and the inner tube (2) is pressed against the inner tube (2) by crushing the tube wall of the outer tube (1) inward. Heavy pipe. The double pipe according to claim 1,
A double pipe characterized in that the outer wall (1) is pressed against the inner pipe (2) by flattening the wall of the pipe from two directions sandwiching the pipe. The double pipe according to claim 1 or 2,
A double pipe characterized in that the crushed portions (20) of the outer pipe are arranged at intervals in the length direction of the outer pipe (1). In the manufacturing method of the double pipe in which the inner pipe (2) for flowing the second fluid is disposed inside the outer pipe (1) for flowing the first fluid,
A double pipe characterized in that the inner pipe (2) is inserted into the outer pipe (1) and the inner wall (2) is pressed against the inner pipe (2) by crushing the wall of the outer pipe (1) inward. Manufacturing method. In the manufacturing method of the double pipe in which the inner pipe (2) for flowing the second fluid is disposed inside the outer pipe (1) for flowing the first fluid,
The inner tube (2) is inserted into the outer tube (1), and in this state, the outer tube (1) and the inner tube (2) are both bent along the length direction at predetermined locations, A method of manufacturing a double pipe, wherein the inner pipe (2) is pressed by crushing the pipe wall of the outer pipe (1) inward. In the manufacturing method of the double pipe in which the inner pipe (2) for flowing the second fluid is disposed inside the outer pipe (1) for flowing the first fluid,
After the inner tube (2) is inserted into the outer tube (1) and the outer tube (1) and the inner tube (2) are end-treated in this state, the outer tube (1) and the inner tube (2 ) Are bent along the length direction at predetermined locations, and then the inner wall (2) is pressed against the inner tube (2) by crushing the tube wall of the outer tube (1) inward. Manufacturing method of heavy pipe. It is a manufacturing method of the double pipe given in any 1 paragraph of Claims 4-6,
A method of manufacturing a double pipe, wherein the pipe wall of the outer pipe (1) is pressed against the inner pipe (2) by flattening it from two directions sandwiching the pipe. It is a manufacturing method of the double pipe given in any 1 paragraph of Claims 4-6,
A method for manufacturing a double pipe, wherein the crushed portions (20) of the outer pipe are arranged at intervals in the length direction of the outer pipe (1).

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