JP2005172195A - 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. The inner pipe 2 is previously formed into a non-circular cross section (for example, an elliptical cross section) with a protruded portion 2A protruded outward in the radial direction, and the outer pipe 1 is formed into a cross section approximately similar to that of the inner pipe 2. Then, the inner pipe 2 is inserted into the outer pipe 1 and the outer pipe 2 is deformed into a circular cross section in such a state, that the outer pipe 2 is put in pressure contact with the protruded portion 2A of the inner pipe. Thus, the outer pipe 1 is fixed to the inner pipe 2 while securing a flow path between the outer pipe 1 and the inner pipe 2. <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. 11, a conventional double pipe is provided with 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. 12, when the double pipe is bent into a shape corresponding to the required piping layout with the inner pipe 2 inserted into the outer pipe 1, the inner pipe 2 and the outer pipe 1 come into 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 eliminate this, if the bending curvature is reduced as shown in FIG. 13 (that is, tight bending) and the inner tube 2 is strongly in contact with the inner wall of the outer tube 1 at the contact points A and B, the chatter noise is generated. 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. 14, the contact part A will be 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 according to the first aspect of the present invention is the double pipe in which the inner pipe for flowing the second fluid is disposed inside the outer pipe for flowing the first fluid, wherein the inner pipe is protruded radially outward. The first fluid is inserted between the outer tube and the inner tube by inserting the outer tube into the outer tube and pressing the outer tube against the protruding portion of the inner tube. The outer pipe and the inner pipe are fixed while securing the flow passage.

  A double tube according to a second aspect of the present invention is the double tube according to the first aspect, wherein the outer tube has a circular cross section.

  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 non-circular cross section is formed continuously over substantially the entire length of the inner pipe. To do.

  A double pipe according to a fourth aspect of the invention is the double pipe according to the first or second aspect, wherein the non-circular cross-sectional portions are formed at intervals in the length direction of the inner pipe. And

  A double tube according to a fifth aspect of the present invention is the double tube according to any one of the first to fourth aspects, wherein the inner tube has an elliptical cross section having two protrusions, or three or more protrusions. It has a polygonal cross section having a portion.

  According to a sixth aspect of the present invention, there is provided a double pipe manufacturing method in which 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, the inner pipe is arranged in a radial direction. The outer tube is formed with a non-circular cross section having an outward projecting portion, and is inserted into the outer tube, and the outer tube is deformed in this state to deform the outer tube with respect to the projecting portion of the inner tube. And the outer tube and the inner tube are fixed while securing the flow path of the first fluid between the outer tube and the inner tube.

  A method of manufacturing a double pipe according to a seventh aspect of the invention is the method of manufacturing a double pipe according to claim 6, wherein the outer pipe is formed in a cross-section substantially similar to the inner pipe in advance. The inner tube is inserted into the outer tube, and in this state, the outer tube is deformed into a circular cross section, whereby the outer tube is pressed against the protruding portion of the inner tube.

  The method for manufacturing a double pipe according to an eighth aspect of the present invention is the method for manufacturing a double pipe in which an inner pipe for flowing a second fluid is disposed inside an outer pipe for flowing a first fluid. After forming an outward projecting portion and a non-circular cross section having a maximum diameter larger than the inner diameter of the outer tube, the inner tube is inserted into the projecting portion of the inner tube. The outer tube is pressed against the outer tube, thereby fixing the outer tube and the inner tube while securing the flow path of the first fluid between the outer tube and the inner tube.

  According to the first aspect of the present invention, the inner tube is formed in a non-circular cross section having a radially outward projecting portion, inserted into the outer tube, and the outer tube is pressed against the projecting portion of the inner tube. As a result, the outer tube and the inner tube are fixed while securing a flow path between the outer tube and the inner tube, so that the inner tube and the outer tube can be securely pressed against each other even when the outer tube is gently bent. It is possible to effectively prevent the occurrence of chatter noise during vehicle vibration. Also, the inner pipe and outer pipe can be combined as independent pipes, and since there are no extra connecting ribs between the inner pipe and outer pipe, manufacturing is easy and the end of the pipe is processed. It does not take time and effort.

  According to the invention of claim 2, since the outer tube has a circular cross section, it can be easily bent in any direction, and workability at the time of bending is improved. Further, wrinkles and crushing are less likely to occur in the bent portion.

  According to the invention of claim 3, since the non-circular cross-sectional portion is formed continuously over substantially the entire length of the inner tube, the inner tube and the outer tube are continuously pressed over the entire length, and the rigidity is increased. Rise.

  According to invention of Claim 4, since the said non-circular cross-section part is formed at intervals in the length direction of an inner tube, the press-contact location of an inner tube and an outer tube exists at intervals. Therefore, by bending at a non-pressure contact portion with low rigidity, the bending can be easily performed regardless of the bending direction.

  According to the invention of claim 5, since the inner tube has an elliptical cross section having two protrusions or a polygonal cross section having three or more protrusions, the inner tube is processed into a non-circular cross section. Is easy to do.

  According to the invention of claim 6, the inner tube is formed in a non-circular cross section having a radially outward projecting portion, inserted into the outer tube, and the cross section of the outer tube is deformed in this state, The outer tube is pressed against the projecting part of the tube, thereby securing the flow path between the outer tube and the inner tube, and fixing the outer tube and the inner tube. However, the inner tube and the outer tube can be securely brought into pressure contact with each other, and chatter noise during vehicle vibration can be effectively prevented. In addition, after the inner tube is inserted, the outer tube and the inner tube are pressed together by deforming the cross section of the outer tube, so that the inner tube can be inserted into the outer tube in a loose state with a gap. Manufacture is easy without the need to apply extra force. In addition, the inner tube and the outer tube can be combined after being manufactured as independent tubes, and the connecting rib provided between the inner tube and the outer tube is unnecessary, so that the processing of the tube end does not take time. .

  According to the invention of claim 7, the outer tube is formed in a cross-section substantially similar to the inner tube in advance, the inner tube is inserted into the outer tube, and the outer tube is deformed into a circular cross section in that state. Since the outer tube is pressed against the protruding portion of the inner tube, the inner tube can be easily inserted into the outer tube and the final outer tube has a circular cross section. Bending can be easily performed in the direction, workability during bending is improved, and wrinkles and crushing are less likely to occur in the bent portion.

  According to the invention of claim 8, the inner tube is inserted into the outer tube after being formed in a non-circular cross section having a radially outward projecting portion and having a maximum diameter dimension larger than the inner diameter of the outer tube. As a result, the outer tube is pressed against the protruding portion of the inner tube, thereby securing the flow path between the outer tube and the inner tube, thereby fixing the outer tube and the inner tube. Although there is resistance when the tube is inserted, there is no need to perform a process of deforming the cross section of the outer tube later, so that the processing process can be simplified. In addition, it is possible to achieve strong pressure contact between the inner and outer pipes by simply combining the inner and outer pipes formed as independent pipes, so that it is possible to effectively prevent chatter noise during vehicle vibrations. Can do. In addition, since no extra connecting rib is required between the inner tube and the outer tube, it does not take time to process the tube end.

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

  FIG. 1 is an explanatory diagram of a double tube and a method for manufacturing the same according to the first embodiment of the present invention. As shown in FIG. 1 (d), 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. It is a structure which does not have a connection rib which keeps the clearance gap between both constant.

  To obtain the double pipe of FIG. 1D, first, as shown in FIG. 1A, a small-diameter inner pipe 2 and a large-diameter outer pipe 1 are prepared as independent pipes each having a circular cross section. Next, by applying a force in the direction shown by the hollow arrow F in (a) to the inner tube 2 and the outer tube 1 having a circular cross section, as shown in (b), the inner tube 2 and the outer tube 1 are connected. These are deformed into elliptic cross sections (non-circular cross sections) that are substantially similar to each other.

  As a method of deforming the cross section into an ellipse, a method of crushing with a pair of rollers 101 as shown in FIG. 2 can be employed. According to this method, the inner tube 2 and the outer tube 1 can be easily processed into a continuous elliptical cross section (non-circular cross section) over the entire length. By processing into an elliptical cross-section in this way, the inner tube 2 has two ridge-line-shaped protruding portions 2A protruding outward in the radial direction.

  Next, the inner tube 2 is inserted concentrically into the outer tube 1 to create the state (c). In this state, by applying a force in the direction shown by the white arrow F in (c) to the outer tube 1, the cross section of the outer tube 1 is deformed into a circular shape as shown in (d). The inner wall of the outer tube 1 is pressed against the two protruding portions 2A. As a result, a double pipe is obtained in which the outer pipe 1 and the inner pipe 2 are fixed while securing a flow path between the outer pipe 1 and the inner pipe 2.

  As a method of reworking the outer tube 1 formed into an elliptical cross section into a circular cross section, as shown in FIG. 3, it is possible to reduce the diameter using a swaging tool 102, or as shown in FIG. The pressing process using the roller 103 may be used. In this case, it is not necessary to return to a complete circular cross section, but it is preferable that the cross section has no corners connected by arcs as large as possible.

  Thus, by forming the inner tube 2 and the outer tube 1 in an elliptical cross section, the inner tube 2 is inserted into the outer tube 1 and the cross section of the outer tube 1 is processed into a circular shape in that state. Since the inner wall of the outer tube 1 is pressed against the protruding portion 2A of the tube 2, for example, the inner tube 2 and the outer tube 1 can be firmly pressed firmly even at a location where the outer tube 1 is gently bent. In addition, it is possible to effectively prevent chatter noise during vehicle vibration.

  Further, since the inner pipe 2 and the outer pipe 1 are manufactured as independent pipes and combined, it is not necessary to provide an extra connecting rib between the inner pipe 2 and the outer pipe 1, and the manufacturing is easy. There is no need for troublesome processing. In addition, since the outer tube 1 is finally returned to a circular cross section, it does not have directionality when bending the finished double tube, and can be easily bent in any direction. In addition to being improved, wrinkles and crushing are less likely to occur in the bent portion. In addition, since the elliptical cross-sectional portion is continuous over substantially the entire length of the inner tube 2, the inner tube 2 and the outer tube 1 are continuously pressed over the entire length, and high rigidity can be exhibited.

  Also, as a manufacturing method, the outer tube 1 and the inner tube 2 are brought into pressure contact by deforming the cross section of the outer tube 1 after inserting the inner tube 2 (returning to a circular cross section). The inner tube 2 can be inserted into the outer tube 1 in a loose state with a gap, and there is no need to apply an extra force when inserting, and the manufacture is easy.

  In the first embodiment, the inner tube 2 and the outer tube 1 are both processed into an elliptical cross section and combined. However, the inner tube 2 and the outer tube 1 are polygons having three or more protrusions. It can also be combined by processing into a cross section. Even if it is a polygonal cross section having three or more protrusions, a triangular cross section or a quadrangular cross section is preferable from the viewpoint of securing a flow path between the inner tube 2 and the outer tube 1.

  FIG. 5 shows a case where the inner tube 2 and the outer tube 1 are combined into a triangular cross section as a second embodiment.

  Also in this case, in obtaining the double pipe of FIG. 5 (d), first, as shown in FIG. 5 (a), a small-diameter inner pipe 2 and a large-diameter outer pipe 1 are prepared as independent pipes each having a circular cross section. Next, as shown in (b), the inner tube 2 and the outer tube 1 are each deformed into a substantially similar triangular cross section (non-circular cross section). By deforming into a triangular cross section, the inner tube 2 has three ridge-shaped protruding portions 2A protruding outward in the radial direction. Here, the projecting portion 2A is processed into an arc shape having a corner as much as possible.

  Next, the inner tube 2 is inserted concentrically into the outer tube 1 to create the state (c), and in that state, the cross section of the outer tube 1 is deformed into a substantially circular shape as shown in (d), The inner wall of the outer tube 1 is pressed against the protruding portion 2A of the inner tube 2. As a result, a double pipe is obtained in which the outer pipe 1 and the inner pipe 2 are fixed while securing a flow path between the outer pipe 1 and the inner pipe 2. In the case of this double tube, the same effect as in the first embodiment can be obtained.

  In the first and second embodiments, the inner tube 2 is continuously processed into a noncircular cross section (elliptical cross section or triangular cross section) over the entire length and combined with the outer tube 1. You may combine with the outer tube | pipe 1 after forming a part at intervals in the length direction of an inner tube | pipe.

  FIG. 6 shows a case where an elliptical cross-section portion (non-circular cross-section portion) 20 is formed in the longitudinal direction of the inner tube 2 and is combined with the outer tube 1 as a third embodiment.

  To obtain the double pipe of FIG. 6D, first, as shown in FIG. 6A, a small-diameter inner pipe 2 and a large-diameter outer pipe 1 are prepared as independent pipes each having a circular cross section. Next, as shown in (b), the inner tube 2 is partially spaced with an interval, and the outer tube 1 is continuously over the entire length, each having an elliptical cross section (non-circular cross section) that is substantially similar to each other. To deform.

  FIG. 7 is a perspective view of the inner tube 2 after deformation. As shown in this figure, the deformed inner tube 2 has elliptical cross-section portions 20 at regular intervals while leaving a circular cross-section portion. The cross section of the transition portion from the circular cross section to the elliptic cross section is smoothly changed. Thus, by processing into an elliptical cross section at intervals, the inner tube 2 can have two ridge-shaped protruding portions 2A protruding outward in the radial direction.

  Next, the inner tube 2 processed in this way is inserted concentrically into the outer tube 1 to create the state (c). In this state, as shown in (d), the cross section of the outer tube 1 is deformed into a circular shape, and the inner wall of the outer tube 1 is pressed against the protruding portion 2A of the inner tube 2. As a result, a double pipe is obtained in which the outer pipe 1 and the inner pipe 2 are fixed while securing a flow path between the outer pipe 1 and the inner pipe 2.

  In the case of this double tube, the same effect as in the first embodiment can be obtained. However, in this double pipe, since the press contact portions of the inner tube 2 and the outer tube 1 exist at intervals, it is easy to bend at a non-pressure contact portion with low rigidity regardless of the bending direction. The advantage that bending can be performed is obtained.

  Moreover, in the said embodiment, although the inner pipe 2 was inserted in the outer pipe 1, the case where the outer pipe 1 was press-contacted to the protrusion part 2A of the inner pipe 2 by changing the cross section of the outer pipe 1 was demonstrated. You can also do the following:

  That is, as shown in each embodiment (fourth to sixth embodiments) of FIGS. 8, 9, and 10, when the inner tube 2 is formed in a non-circular cross section (full length or partial), the maximum diameter dimension is obtained. The inner tube 2 is processed into a non-circular cross section in which the major axis dimension in the case of an ellipse and the diameter of a circumscribed circle in the case of a triangle is larger than the inner diameter D1 of the outer tube 1. Then, the inner tube 2 is inserted into the outer tube 1 that has been left in a circular cross section. Then, the inner wall of the outer tube 1 can be pressed against the protruding portion 2A of the inner tube 2.

  That is, in order to insert the inner tube 2 into the outer tube 1, the inner tube 2 must be pushed into the outer tube 1 while utilizing the spring property of the outer tube 1 or the inner tube 2. In this state, the inner tube 2 and the outer tube 1 can be strongly pressed by the spring reaction force. That is, the dimensional difference between D1 and D2 is like a fitting allowance, and the inner tube 2 and the outer tube 1 can be brought into pressure contact with a force corresponding to this dimensional difference, whereby the outer tube 1 and the inner tube 2 are brought into contact with each other. A double pipe in which the outer pipe 1 and the inner pipe 2 are fixed is completed while securing a flow path between the two.

  When such a manufacturing method is adopted, there is resistance when the inner tube 2 is inserted into the outer tube 1, but there is no need to perform a process of deforming the cross section of the outer tube 1 later. It can be simplified. Other effects are the same as in the above embodiment.

It is sectional drawing used for description of the double tube and manufacturing method of 1st Embodiment of this invention, (a)-(d) is each process drawing. It is a figure which shows the Example of the process of (b) of FIG. It is a figure which shows the Example of the process of (d) of FIG. It is a figure which shows another Example of the process of (d) of FIG. It is sectional drawing used for description of the double tube and manufacturing method of 2nd Embodiment of this invention, (a)-(d) is each process drawing. It is sectional drawing used for description of the double tube and manufacturing method of 3rd Embodiment of this invention, (a)-(d) is each process drawing. It is a perspective view of the inner tube | pipe obtained at the process of (b) of FIG. It is sectional drawing used for description of the double tube and manufacturing method of 4th Embodiment of this invention, (a)-(c) is each process drawing. It is sectional drawing used for description of the double tube and manufacturing method of 5th Embodiment of this invention, (a)-(c) is each process drawing. It is sectional drawing used for description of the double tube and manufacturing method of 6th Embodiment of this invention, (a)-(c) is each process drawing. 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

DESCRIPTION OF SYMBOLS 1 Outer tube 2 Inner tube 2A Protrusion part 20 Oval cross section (non-circular cross section)
D1 Inner diameter of outer tube D2 Maximum diameter of inner tube

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 formed in a non-circular cross section having a radially outward projecting portion (2A) and then inserted into the outer tube (1), and the inner tube projecting portion (2A) ) With the outer pipe (1) being pressed against the outer pipe (1) and the inner pipe (2) while securing the flow path of the first fluid between the outer pipe (1) and the inner pipe ( A double pipe characterized by fixing 2). The double pipe according to claim 1,
A double pipe characterized in that the outer pipe (1) has a circular cross section. The double pipe according to claim 1 or 2,
The non-circular cross section is formed continuously over substantially the entire length of the inner pipe (2). The double pipe according to claim 1 or 2,
The double pipe according to claim 1, wherein the non-circular cross section (20) is formed at intervals in the length direction of the inner pipe (2). The double pipe according to any one of claims 1 to 4,
The double pipe, wherein the inner pipe (2) has an elliptical cross section having two protrusions (2A) or a polygonal cross section having three or more protrusions (2A). 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 formed in a non-circular cross section having a radially outward projecting portion (2A), and then inserted into the outer tube (1), and in that state, the outer tube (1) The outer tube (1) is pressed against the protruding portion (2A) of the inner tube by deforming the cross section of the inner tube, and thereby the first tube is placed between the outer tube (1) and the inner tube (2). A method of manufacturing a double pipe, wherein the outer pipe (1) and the inner pipe (2) are fixed while securing a fluid flow passage. It is a manufacturing method of the double pipe according to claim 6,
The outer tube (1) is formed in a cross section substantially similar to the inner tube (2) in advance, and then the inner tube (2) is inserted into the outer tube (1). A method of manufacturing a double pipe, wherein the outer pipe (1) is pressed against the protrusion (2A) of the inner pipe by deforming 1) into a circular cross section. 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 pipe (2) is formed in a non-circular cross section having a radially outward projecting portion (2A) and having a maximum diameter dimension (D2) larger than the inner diameter (D1) of the outer pipe (1). After that, the outer tube (1) is inserted into the outer tube (1) to bring the outer tube (1) into pressure contact with the protruding portion (2A) of the inner tube, thereby the outer tube (1) and the inner tube. A method of manufacturing a double pipe, wherein the outer pipe (1) and the inner pipe (2) are fixed while securing the flow path of the first fluid between (2) and (2).

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