JPH04149328A - Double vacuum pipe - Google Patents

Abstract

PURPOSE:To facilitate the manufacture of a double vacuum pipe by defining a vacuum space between an inner pipe composed of a curved part fitted thereon with a spacer and straight parts on both sides of the curved part, and an outer pipe composed of an elbow through which the straight parts of the inner pipe can pass, and straight pipe starts joined to both ends of the elbow. CONSTITUTION:A spacer 6 is fitted on and welded to a curved part 6 of an inner pipe 2 which is formed by bending. Then, an elbow 9 is inserted onto the inner pipe 2 from the free end of a straight pipe part 8 thereof, and is positioned on the curved part 6. Further, coupling members 4 are seal-welded to the inner peripheries of first and second straight pipe parts 10, 11 which are part of an outer pipe 3 at one end thereof, and a tip pipe 12 is attached to either one thereof. Then, the first and second straight pipes 10, 11 are inserted into the inner pipe 2 from both ends of the latter, and the coupling members 4, 4 are welded thereto. Then, evacuation is made so as to form a vacuum space S. Thereby it is possible to facilitate the manufacture of the double vacuum pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vacuum double pipe having a vacuum double structure used for preventing freezing of water pipes, keeping heat of transfer pipes for various fluids, and the like.

(Prior Art) Conventionally, in order to increase insulation by making not only the straight portions of pipes such as water pipes but also the curved portions a vacuum double structure, methods have been proposed in Japanese Patent Application Laid-Open No. 214625/1999 and Japanese Patent Application Laid-Open No. 1-214626.
Vacuum double bend joints have been proposed in publications such as No.

The former involves inserting an inner tube having the same radius of curvature as the outer tube into a curved outer tube from one end along the curved axis;
After both ends of the outer tube are made to protrude to seal the space between both ends of the outer tube and the inner tube, the air between the inner tube and the outer tube is evacuated to form a vacuum space.

In the latter case, a bellows-like flexible part is formed at the center of the inner tube and the outer tube, a vacuum space is formed between them in the same way as the former, and then the flexible parts are bent at the same time. It is.

(Problem to be Solved by the Invention) However, in the former case, if the inner tube or the outer tube has a long straight portion continuous to the curved part, the inner tube cannot be inserted into the outer tube. , it has a knot structure consisting only of curved parts. Therefore, in order to connect this vacuum bending joint and a vacuum double pipe, it is necessary to first connect the inner pipes and cover the surrounding area with a heat insulating material, etc., and only this connection part has a vacuum double structure. This has the disadvantage that the heat insulation properties are impaired.

On the other hand, the latter method has the problem that processing to form the bellows-like flexible portion is difficult and costs are considerable.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vacuum double tube that can be easily manufactured even if the inner tube has a continuous straight portion in the curved portion.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an inner tube having a straight portion on both sides of a curved portion, and an elbow that is sheathed on the inner tube and allows the straight portion of the inner tube to be inserted. and an outer tube with straight pipe sections joined to both ends, and a vacuum space is formed between the inner tube and the outer tube.

Further, a spacer may be provided on at least one of the outer surface of the curved portion of the inner tube or the inner surface of the elbow of the outer tube, and faces the other with a small gap.

(Function) According to the above configuration, the elbow of the outer tube can be inserted through the straight portion of the inner tube.After inserting the elbow from the end of the straight portion of the inner tube and positioning it at the curved portion, An outer tube can be formed by joining straight parts to both ends of the elbow.

In addition, the spacer placed between the curved part of the inner tube and the elbow of the outer tube prevents mutually symmetrical thermal deformation of the bent part due to the temperature difference between the inner tube and outer tube that occurs during exhaust treatment in the heating furnace. Prevented. As a result, the difference in thermal expansion appears exclusively as a difference in expansion between the straight portions of the inner tube and the outer tube, so a vacuum space with a uniform gap is formed between the inner tube and the outer tube.

(Example) Next, one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a vacuum double tube 1 according to the present invention, which is composed of an inner tube 2, an outer tube 3, a connecting member 4, and a spacer 5.

The inner tube 2 is formed by bending with a predetermined radius of curvature to form a curved portion 6 and straight portions 7.8 at both ends thereof.

The outer tube 3 has a larger diameter than the inner tube 2 and has approximately the same radius of curvature as the curved portion 6, and includes an elbow 9 through which the straight portion 7 or 8 of the inner tube 2 can be inserted. a first welded to one end;
It consists of a straight pipe part 0 and a second straight pipe part 11 welded to the other end, and is sheathed on the outside of the inner pipe 2. In addition, a tip tube 12 that serves as an exhaust tube during vacuum evacuation processing, which will be described later, protrudes from the outer surface of the No. It is covered and protected by a chip cover 14.

The connecting member 4 has a ring shape with a U-shaped cross section, and is connected to the first connecting member 4 of the outer tube 3. It is installed between the tip of the second straight tube section 10 and the inner tube 2 to seal the vacuum space S between the inner tube 2 and the outer tube 3.

The spacer 5 is made of a ring-shaped plate material, and is
It is inserted through the center of the curved part 6 and fixed appropriately. The outer peripheral end of this spacer 5 faces the inner peripheral surface of the elbow 9 of the outer tube 3 with a slight gap.

The vacuum double tube having the above configuration is manufactured as follows.

First, the inner tube 2 is bent to form a curved portion 6, and the spacer 5 is inserted into the curved portion 6 and fixed by welding. next,
As shown in FIG. 2, the elbow 9 is inserted from the tip of the straight pipe N8 of the inner pipe 2 and positioned in the curved part 6. On the other hand, outer tube 3
The connecting member 4 is fixed to the inner peripheries of the ends of the first straight pipe part 10 and the second straight pipe part II, which are part of the first straight pipe part 10, by knot welding.
The tip tube 12 is attached in advance. And the first
Insert the straight pipe part 10 from one side of the inner pipe 2, and insert the straight pipe part 10 into the second straight pipe part 11.
Insert from the other side of the inner tube 2. Next, elbow 9 and 1
．． Contact portion of second straight pipe portions 10, 11 and connecting member 4.4
and the inner tube 2 are joined by welding the entire circumference.

Here, since the spacer 5 is interposed between the curved part 6 of the inner tube 2 and the elbow 9 of the outer tube 3, the inner tube 2 is displaced in the direction perpendicular to the plane of the paper in FIG. 1 and comes into contact with the outer tube 3. A space S' with a uniform gap is created between the inner tube 2 and the outer tube 3.
is formed.

Next, the structure assembled in this way is placed in a vacuum heating furnace, the air in the space S° between the inner tube 2 and the outer tube 3 is evacuated, and the tip of the tip tube 12 is crushed and vacuum sealed. .

As a result, a vacuum space S is formed between the inner tube 2 and the outer tube 3.

During this vacuum evacuation process, the outer tube 3 is directly exposed to the furnace heat.
A difference in thermal expansion occurs due to the temperature difference between the inner tube 2 and the inner tube 2, which does not directly receive furnace heat except for both ends.

However, due to the spacer 5 disposed between the curved portion 6 of the inner tube 2 and the elbow 9 of the outer tube 3, the inner tube 2 at the bent portion
Since relative thermal deformation between the inner tube 2 and the outer tube 3 is prevented,
The difference in thermal expansion between the outer tube 3 and the outer tube 3 appears as a difference in axial expansion of the straight sections, which is absorbed by the connecting member 4.4. Therefore, even after this evacuation process, a uniform gap is maintained in the space between the inner tube 2 and the outer tube 3.

Finally, the tip of the tip tube 12 is protected by covering it with a cap I4 filled with a sealing material 13.

FIG. 3 shows an example in which the vacuum double pipe 1 manufactured as described above is applied as an antifreeze device for water pipes. In this example, one end of the vacuum double pipe I is buried underground and connected to a drain valve 22 connected to the end of a water pipe 21.
The other end side is raised from the ground to the outdoors 102 along the outer wall 101 of the building 100, is bent horizontally, penetrates the outer wall +01, is guided indoors 103, and has a faucet 25 connected to the tip. In addition, 23 is a protection pipe of the valve stem of the water drain valve 22,
24 is a cook.

Snake c72 with the cock 24 of the water drain valve 22 closed.
5, tap water is discharged from the water pipe 21 via the vacuum duplex W1. 1 double vacuum tube installed outdoors 102
A vacuum space S is formed between the inner tube 2 and the outer tube 3, and the outer tube 3
The vacuum space S insulates the outside air outside the pipe 2 and the tap water inside the inner pipe 2. Therefore, the tap water will not freeze even if the outer tube 3 is exposed to cold air.

In addition, even if the outer peripheral end of the spacer 5 provided between the curved part 6 of the inner tube 2 and the elbow 9 of the outer tube 3 remains in contact with each other due to thermal deformation during the exhaust treatment, ,
Since it is in a point or line contact state, there is little heat conduction from the inner tube 2 to the outer tube 3 side via the spacer 5, and the heat insulation performance is not impaired.

In this antifreeze device, the vacuum double pipe l is connected from the ground to the outer wall +
01 and has no joints, a continuous vacuum space S is obtained and excellent heat insulation properties are obtained.

In the above embodiment, the spacer 5 is connected to the curved portion 6 of the inner tube 2.
Although it is fixed to the outer circumferential surface of the elbow 9 of the outer tube 3, it may be fixed to the inner circumferential surface of the elbow 9 of the outer tube 3, or may be provided to both the inner tube 2 and the outer tube 3. Further, the shape of the spacer 5 is not limited to a ring, but may be simply a protrusion fixed at a plurality of locations along the outer periphery.

Furthermore, the vacuum double pipe according to the present invention can be applied not only to preventing water pipes from freezing, but also as a heat retention device for various fluids such as fluids in food-related manufacturing processes.

(Effect of the invention) As is clear from the above explanation, according to the invention according to claim 1, the elbow of the outer tube can be inserted into the straight part of the inner tube, so that the straight part of the inner tube can be Even if it is long, it can be manufactured into a container. Therefore, for example, when used as a water pipe that rises from the ground and is piped indoors,
It is sufficient to use one of these vacuum double tubes, and an excellent antifreeze effect can be obtained.

Further, according to the invention according to claim 2, the spacer provided between the curved portion of the inner tube and the elbow of the outer tube prevents misalignment between the inner tube and the outer tube at the bent portion due to thermal deformation when forming a vacuum space. As a result, a vacuum space with uniform gaps is formed.
High insulation properties are maintained.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of the vacuum double pipe according to the present invention, Fig. 2 is a front view showing the state when the elbow is attached, and Fig. 3 is a cross section of a water pipe antifreeze device using the vacuum double pipe. It is a diagram. 1. Vacuum double tube, 2. Inner tube, 3. Outer tube,
5... Spacer, 6... Curved part, 8... Straight part, 9... Elbow, 10.11... First and second straight pipe part. Patent applicant Zojirushi Mahobin Co., Ltd. Agent Patent attorney Aoyama Aoyama and one other person Figure 1

Claims (2)

[Claims] (1) Consisting of an inner tube that has straight sections on both sides of the curved section, and an outer tube that is attached to the inner tube and has straight sections joined to both ends of an elbow that can be inserted through the straight section of the inner tube. A vacuum double tube characterized by forming a vacuum space between an inner tube and an outer tube. (2) A vacuum double tube, characterized in that a spacer is disposed on at least one of the outer surface of the curved portion of the inner tube or the inner surface of the elbow of the outer tube, and faces the other with a small gap.