JP2911094B2 - Vacuum double tube joint structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double vacuum system applicable to the prevention of freezing of water pipes and house pipes bridged between river banks in a cold region, transportation of liquid nitrogen, etc., and hot water supply pipes of buildings and the like. The present invention relates to a pipe joint structure.

[0002]

2. Description of the Related Art In recent years, for example, when a water pipe is bridged between river banks in a cold region, a vacuum double pipe made of stainless steel is used as a water pipe so as to prevent freezing of water inside due to the influence of outside air. It is becoming. Since such a vacuum double tube cannot be made longer than a predetermined length due to manufacturing restrictions, a method of connecting a plurality of such tubes by a joint is adopted. In this case, since the heat insulating performance at the joint portion is inferior to other portions, when the outside air temperature becomes extremely low, there is a problem that water inside freezes.

For this reason, conventionally, as a joint structure for a vacuum double tube, for example, those disclosed in Japanese Utility Model Publication No. 1-43595 or Japanese Utility Model Application Laid-Open No. 2-80295 have been devised.

In the former joint structure, as shown in FIGS. 7 and 8, the closed end of the vacuum double tube 40 is a small-diameter tube 41, and a vacuum double tube 42 connected to the vacuum double tube 40. By forming a relief recess 43 in which the small-diameter pipe 41 is positioned at the closed end of the inner pipe 40, the distance of the air layer formed between the inner pipe 40a and the outer pipe 40b is increased, and the heat insulation performance is increased. It was done.

In the latter joint structure, as shown in FIG. 9, a heat insulating material 46 is filled in an outer peripheral space formed by an inner tube 44a and a vacuum projection 45 of both vacuum double tubes 44, and furthermore, Double pipes 47 and 48 are provided on the outer circumference,
The space formed by these is evacuated.

[0006]

However, in the former joint structure, it is necessary to position the outer surface of the small-diameter pipe 41 and the inner surface of the relief recess 43 in a non-contact manner.
Since there is a limit in manufacturing to increase the size of the small-diameter tube 41, there is a problem that desired heat insulation performance cannot be obtained.

Further, since the pipes forming the small diameter pipe 41 and the relief recess 43 have the same thickness as the inner pipe 40a of the vacuum double pipe 40, heat is easily transmitted, which causes the heat insulation performance to deteriorate. ing.

Further, if the fluid has a very low temperature, such as liquid nitrogen, the sealed state between the inside of the inner tube and the outside air is released by the heat shrinkage of the inner tube 40a, as shown in FIG. Innovative structural measures are required. That is, a tapered surface is formed on the inner surface of one of the pipes, a step is formed on the outer circumference of the other pipe inserted into the pipe, and an annular seal ring having a substantially U-shaped cross section is attached to the step. However, there is a problem that the structure is complicated and the manufacturing cost is increased.

On the other hand, in the latter joint structure, after the heat insulating material 46 is filled, the pipes 47 and 48 must be further provided in two layers and evacuated, so that the number of processing steps is large, and the processing time and the processing cost are reduced. There is a problem. In view of the above problems, an object of the present invention is to provide a joint structure for a vacuum double tube that can be manufactured at a low cost with a simple structure and has high heat insulation performance.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a joint structure for a vacuum double pipe connecting closed ends, wherein a connecting end of one vacuum double pipe has an annular vacuum. At least one or more protrusions are formed, and at least two or more annular vacuum protrusions are formed at the connection end of the other vacuum double tube, and the one vacuum protrusion is in non-contact between the vacuum protrusions. The relief recess and the vacuum projection located in the relief recess are formed by connecting the outer tube and the inner tube of each vacuum double tube facing each other via a sealing member. A pipe forming an adiabatic air layer between the pipes and forming the vacuum protrusion is thinner, preferably 0.1 mm thick, as compared with the inner pipe of the vacuum double pipe.
〜0.5 mm.

[0011] A radiation layer may be formed on at least the pipe of the vacuum double pipe in a range where the vacuum projection is located.

[0012]

According to the above construction, if a vacuum double tube is joined,
One of the vacuum projections is positioned in the escape recess in a non-contact manner, and when the outer tubes are joined to each other, the sealing member is in a compressed state, and an adiabatic air layer is formed between the inner tube and the outer tube. .

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a joint structure of the vacuum double tubes 1 and 2, and a closed end of the vacuum double tube 1 on the left side is formed with one annular vacuum protrusion 3. This vacuum projection 3 is provided with an annular packing 5 (FIG. 4) at one end of cylindrical thin pipes 4a and 4b.
4 (a)) or a seal ring 6 (see FIG. 4 (b)) to form a double pipe, and the other end is connected to the closed end of the vacuum double pipe 1 by inner and outer seal rings 7. , 8. In this case, while the thickness of the inner pipe 1a and the outer pipe 1b forming the vacuum double pipe 1 is about 1 mm, the thickness of the thin pipes 4a and 4b forming the vacuum projection 3 is, for example, 0.5 mm. , Preferably 0.1 mm to 0.5 mm. That is, the thickness of the thin pipes 4a and 4b is set to 50 with respect to the inner pipe 1a and the outer pipe 1b.
% Or less, it is possible to effectively prevent heat conduction from the inner pipe 1a to the thin pipe 4a.

The vacuum double tube 1 is provided with a chip tube 9 in the middle of the outer tube 1b. This tip tube 9
Is a cover 10 made of silicon rubber whose outer peripheral portion is covered with a cylindrical body 10a made of stainless steel and provided in the opening thereof.
By solidifying b, it is sealed.
Reference numeral 11 denotes a getter which maintains the degree of vacuum in the vacuum double tube 1 after the sealing for a long time.

Further, the vacuum double tube 1 has an outer tube 1b.
A thick flange 12 is formed at an end of the flange 12. An annular seal groove 13 is formed in the flange 12, and a packing 14 as a seal member is provided therein.

On the other hand, at the closed end of the other vacuum double tube 2, two vacuum projections 15, 16 are formed. The two vacuum projections 15 and 16 are formed by inserting a double pipe formed of thin-walled pipes 17a and 17b and a seal ring 18 inward from the ends, and welding the outer and inner peripheral sides of the seal rings 19 and 20 to each other. It is formed by fixing with, for example. A relief recess 21 is located between the vacuum projections 15 and 16 where the vacuum projection 3 is located.

The seal ring 20 on the inner peripheral side of the vacuum double tube 2 is provided at a position slightly depressed from the end face of the vacuum double tube 2, and has an annular positioning groove 22 (FIG.
(See (a)). An annular packing 23 positioned in the positioning groove 22 is provided on the outer peripheral end of the inner tube 2 a of the vacuum double tube 2.
The packing 23 slightly protrudes from the end face of the thick flange 24 formed at the edge of the outer tube 2b. In addition, a seal groove 25 is formed in the flange 24, and the packing 14 is held by the seal groove 13 of the flange 12.

Further, an anti-vibration ring 26 is provided on the outer peripheral portion of the inner tube 2a of the vacuum double tube 2 so that the thin-walled pipe 17a does not come into contact with the inner tube 2a. The copper foil constituting the radiation layer 27 is wound. The radiant layer 27 is for preventing heat radiation when a liquid having a temperature higher than the outside air temperature flows in the inside, and for preventing heat absorption in the reverse case, the outer circumference of the inner pipe 1a and the thin pipe 4a. It is also formed on the surface. Note that the radiation layer 27 may be made of metal foil such as copper or aluminum, metal plating, or the like.

Incidentally, the dimension between the inner and outer peripheral surfaces of the relief recess 21 is slightly larger than the dimension between the inner and outer peripheral surfaces of the vacuum projecting portion 3, and when the two vacuum double tubes 1 and 2 are connected. A gap that does not contact each other can be formed. However, this gap is preferably set to 1 mm or less so that the air does not flow.

As described above, the vacuum double tubes 1 and 2 provided with the vacuum projection 3 and the relief recess 21 are connected as follows. That is, first, the vacuum projecting portion 3 is released and the concave portion 2 is released.
1, the packing 23 comes into contact with the seal ring 7.
2 and 24 are brought into contact with each other. Thereby, the inner tubes 1a, 2
It is possible to surely shut off the fluid inside a from the outside air at the position closest to the inner tubes 1a and 2a.

The packing 14 provided on the flanges 12 and 24 of the outer tubes 1b and 2b shuts off the space formed by the vacuum projecting portion 3 and the relief recess 22 from the outside air, thereby forming the inner tube 1a. , 2a and the outer tubes 1b, 2b are formed with a heat insulating air layer, and the flanges 12, 24 are connected to each other by bolts or the like, as shown in FIG.

The holding fitting 28 shown in FIG. 5 has a pair of semicircular members 30a and 30
b is inserted through a cutout (not shown) formed in the other end of the other semicircular member 30b with a screw portion 31 rotatably attached to the other end of one semicircular member 30a. Screw part 31
The nut 32 is screwed into the nut 32. However, the connection state is more stable when the flanges 12 and 24 are connected by bolts, but the holding fitting 28 shown in FIG. 5 is lighter.

As described above, the heat-insulating air layer formed between the inner tubes 1a and 2a and the outside air can be about twice as large as the protrusion size of the vacuum protrusion 3, and the heat insulation performance is improved. Very good. As shown in FIGS. 1 and 2, this air layer is formed by a packing 23 provided on the vacuum projection 3.
The heat insulation performance may be further improved by dividing the airflow to prevent the flow of air. Further, if the air layer has a small gap through which air does not easily flow as described above, it is possible to further enhance the heat insulating performance.

In the above embodiment, the packing 23 is
Although the seal ring 7 formed to be perpendicular to the axial direction of the vacuum double tubes 1 and 2 is pressed, the seal ring 7 may have an inclined structure as shown in FIG. . According to this, without forming the positioning groove 22 in the seal ring 20, the packing 23 can be positioned and the sealing state can be made more reliable.

In the above-described embodiment, the vacuum projection 3 is formed on one vacuum double tube 1 and the relief recess 21 where the vacuum projection 3 is located is formed on the other vacuum double tube 2. However, as shown in FIG. 6, two or more vacuum projections 29 are provided on both vacuum double tubes 1 and 2, and a vacuum projection 29 formed on one vacuum double tube 1 or 2 is formed on the other. The inner tubes 1a,
If the distance between the air layers formed between the outer tube 2a and the outer tubes 1b, 2b is made longer, such as 3X, 4X, etc., the heat insulation performance can be further enhanced.

Further, when the temperature difference between the fluid to be conveyed and the outside air temperature is very large, for example, when liquid nitrogen is caused to flow, the outer tubes 1b and 2b are indicated by two-dot chain lines in FIG.
The bellows-shaped expansion / contraction absorber 30 may be formed in b.
According to this, even if the inner tubes 1a, 2a are shorter than the outer tubes 1b, 2b due to thermal shrinkage, the shrinkage absorbing portion 3
The length of the outer tubes 1b and 2b is adjusted by 0, and the load applied to the closed end face is reduced.

[0027]

As is apparent from the above description, according to the joint structure for a vacuum double tube according to the present invention, a vacuum projection is formed at the closed end of the vacuum double tube while the vacuum double tube is formed. At the closed end of the vacuum double tube to be joined to the tube, not only is a relief recess in which the vacuum protrusion is positioned at least on the inner and outer circumferences in a non-contact manner, but also a pipe constituting the vacuum protrusion and the relief recess. Since the pipe is made thin, the amount of heat transmitted through the pipe itself is reduced, and the heat insulation performance can be improved.

Further, if a radiation layer is formed on the pipe at the connection portion of the vacuum double pipe, when it is necessary to maintain the fluid temperature higher than the outside air temperature, it is necessary to release heat and keep it low. In this case, heat absorption is prevented, and the heat insulation performance can be further improved.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a state before connection of a joint structure for a vacuum double pipe according to the present embodiment.

FIG. 2 is a front sectional view showing a connection state of FIG. 1;

FIG. 3 is a partial cross-sectional view showing a mounting structure of a packing in a seal ring on an inner peripheral side in FIG. 2;

FIG. 4 is a partial cross-sectional view showing a packing mounting structure at a distal end portion of a vacuum protrusion of FIG. 2;

FIG. 5 is a front view of a holding bracket for fixing a flange portion of the vacuum double tube of FIG. 2;

FIG. 6 is a partial sectional view showing a joint structure of a vacuum double tube according to another embodiment.

FIG. 7 is a front sectional view showing a joint structure of a vacuum double tube according to a conventional example.

FIG. 8 is a partially enlarged view of FIG. 7;

FIG. 9 is a front sectional view showing a joint structure of a vacuum double tube according to another conventional example.

[Explanation of symbols]

1,2 ... Vacuum double tube, 1a, 2a ... Inner tube, 1b, 2b ...
Outer tube, 3, 15, 16: vacuum projection, 21: relief recess, 23: packing (seal member).

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16L 59/18 E03B 7/10 F16L 59/06

Claims (2)

(57) [Claims] 1. A vacuum double pipe joint structure for connecting closed ends, wherein at least one annular vacuum projection is formed at a connection end of one vacuum double pipe, and the other vacuum double pipe is formed. At least two or more annular vacuum projections are formed at the connection end of the vacuum projection, and between the vacuum projections, a relief recess is formed in which the one vacuum projection is positioned in a non-contact manner. By connecting the outer tube and the inner tube facing each other via a seal member, a heat insulating air layer is formed between the relief concave portion and the vacuum protrusion portion located in the relief concave portion to constitute the vacuum protrusion portion. A joint structure for a vacuum double pipe, wherein a pipe to be formed is thinner than an inner pipe of the vacuum double pipe. 2. The joint structure for a vacuum double pipe according to claim 1, wherein a radiation layer is formed on at least a pipe of the vacuum double pipe in a range where the vacuum protrusion is located.