JPH0718092U - Double pipe - Google Patents

Abstract

(57) [Summary] [Purpose] A double tube formed by bending a predetermined part can be manufactured by a simple method, and the quality of the double tube is improved. [Structure] The outer pipe 21 is formed of a cylindrical pipe, the inner pipe 22 is formed of a spiral pipe, and a first fluid is allowed to pass through the inner pipe 22, and a second fluid is formed between the outer pipe 21 and the inner pipe. Pass it through the pipe 22. When bending such a double pipe at a desired portion, if the outer pipe 21 is bent,
As the distance between the ridges on the inside of the bent portion of the inner pipe 22 decreases, the distance between the ridges on the outside of the bent portion increases.
The ridge does not deviate to one side due to the contact of the mountain portion with the inner peripheral surface of the outer pipe 21. Further, even in the use state, many peaks of the inner pipe 22 come into contact with the inner peripheral surface of the outer pipe 21,
Since the inner pipe 22 is supported on the inner circumference of the outer pipe 21 by a number of places, the inner pipe 22 is not easily damaged.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a double tube formed by coaxially inserting an inner tube into an outer tube.

[0002]

[Prior art]

 2. Description of the Related Art Conventionally, as shown in FIG. 2, an inner pipe 12 is coaxially inserted in an outer pipe 11, a first fluid is allowed to flow in the inner pipe 12, and a space between the inner pipe 12 and the outer pipe 11 is provided. A double tube for flowing a second fluid different from the above is well known. Then, when bending is provided at a predetermined portion of such a double pipe, the outer pipe 11 and the inner pipe 12 interfere with each other (see FIG. 3A), and the inner pipe 12 becomes flat, or In order to prevent the tube from being damaged, the outer tube 11 is bent by filling the inside tube 12 and the space between the inner tube 12 and the outer tube 11 with sand or ice.

[0003]

[Problems to be solved by the device]

 However, the above-mentioned conventional manufacturing method has a problem that a large-scale facility for packing sand, ice, etc. in the pipe is required, and the manufacturing cost of the double pipe increases. Even in the double pipe constructed in this way, the inner pipe 12 is supported by the outer pipe 11 only at its both ends (see FIG. 2B), and therefore is damaged by vibration at a portion near the supporting portion. There are also things to do.

The present invention has been made to solve the above problems, and an object thereof is to provide a double tube which can be manufactured by a simple method and has good quality.

[0005]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, a structural feature of the present invention is a double pipe in which an inner pipe is coaxially inserted in an outer pipe and bending is performed at a predetermined portion. The outer tube is a cylindrical tube and the inner tube is a spiral tube.

[0006]

[Operation and effect of the device]

 With the above configuration, when the outer pipe is bent, the inner pipe is made up of a spiral pipe, so the distance between the ridges on the inside of the bend becomes smaller and the distance between the ridges on the outside of the bend becomes larger. Therefore, the inner pipe is prevented from being biased to one side by the contact of the mountain portion with the inner peripheral surface of the outer pipe. As a result, even if the outer pipe is bent without filling the pipe with sand or ice, the outer pipe and the inner pipe may interfere with each other and the inner pipe may become flat or one of the pipes may be damaged. There is no. Therefore, according to the present invention, a good quality double tube can be easily manufactured. Even after the double pipe is manufactured, many crests of the inner pipe made of spiral pipe abut on the inner peripheral surface of the outer pipe, and the inner pipe is supported on the inner periphery of the outer pipe by many points. Therefore, even if the double pipe vibrates, the inner pipe will not be easily damaged.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a part of the double pipe according to the embodiment in a cutaway manner. This double pipe is an inner pipe composed of an outer pipe 21 made of a metal cylindrical pipe and a metal spiral pipe coaxially inserted into the outer pipe 21 (a pipe having a spiral wall surface). And a tube 22. An inflow pipe 24 and an outflow pipe 25 are fixed to the inner circumferences of both ends of the inner pipe 22 via an annular spacer 23 (only one of which is shown), and the first fluid (for example, gas ) Flows out from the outflow pipe 25 through the inside of the inner pipe 22. On the other hand, an inflow pipe 26 and an outflow pipe 27, which communicate with the inside of the outer pipe 21 through through holes provided in the outer pipe 21, are fixed to the outer peripheral surfaces of both ends of the outer pipe 21, and the inflow pipe 26 flows in. The second fluid (for example, hot water) flows out from the outflow pipe 27 through the passage between the outer pipe 21 and the inner pipe 22.

When the double pipe having the above-described structure is bent at a predetermined portion, if the outer pipe 21 is bent, the inner pipe 22 is composed of a spiral pipe, so that the distance between the ridges inside the bent portion is small. As it becomes smaller, the distance between the peaks outside the bent portion becomes larger (see C in FIG. 1), and the inner tube 22 is prevented from being biased to one side due to the contact of the peak with the inner peripheral surface of the outer tube 21. As a result, even if the outer pipe is bent without filling the pipe with sand or ice, the outer pipe 21 and the inner pipe 22 interfere with each other to flatten the inner pipe 22, or Since it will not be damaged, a good quality double tube can be manufactured by a simple method. Even after the double pipe is manufactured, many crests of the inner pipe 22 are in contact with the inner peripheral surface of the outer pipe 21 so that the inner pipe 22 is supported on the inner periphery of the outer pipe 21 by a large number of places. Therefore, even if the double pipe vibrates, the inner pipe 22 is not easily damaged.

[Brief description of drawings]

FIG. 1 is a partially cutaway view of a double pipe showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional double pipe.

FIG. 3 is an explanatory diagram for explaining a problem of a conventional double pipe.

[Explanation of symbols]

21 ... Outer pipe, 22 ... Inner pipe, 24, 26 ... Inflow pipe, 25, 27 ... Outflow pipe.

Claims (1)

[Scope of utility model registration request] 1. A double pipe formed by coaxially inserting an inner pipe into an outer pipe and bending it at a predetermined portion, wherein the outer pipe is a cylindrical pipe and the inner pipe is spiral. A double tube characterized by being composed of tubes.