JP4185690B2 - Metal vacuum structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal vacuum structure such as a vacuum heat insulating pipe .
[0002]
[Prior art]
A conventional vacuum structure such as a metal thermos evacuates a space closed by a constituent member composed of a first metal member located on the inner side and a second metal member located on the outer side. And the outside of the second metal member are insulated. And in order to hold | maintain this heat insulation over a long period, the getter which absorbs the gas discharge | released and liberated from a metal member is installed in the vacuum space between a 1st metal member and a 2nd metal member. .
[0003]
The getter has a pellet shape, a linear shape, or a plate shape, and is fixed to a surface located in the space of the first metal member or the second metal member with a fastener, or pressed with copper or aluminum foil for preventing heat radiation. It is designed to be attached or engulfed.
[0004]
[Problems to be solved by the invention]
However, the metal vacuum structure has a problem that usable applications are limited by the performance of the getter used. That is, when the metal member provided with the getter becomes higher than the activation temperature of the getter, the getter releases the adsorbed gas by the heat transfer. If it does so, the vacuum degree of space will fall with the emitted gas, and heat insulation performance will fall. For this reason, this type of metal vacuum structure needs to use a getter having an activation temperature corresponding to the environment (temperature) to be used. However, a getter that can be used under conditions of high temperature (800 to 900 ° C.) needs to apply a high heating temperature in the step of activating, and it takes time, so that the vacuum structure is expensive. There is.
[0005]
Therefore, the present invention provides a metal vacuum structure that can withstand a high temperature environment without using an expensive getter having a high activation temperature.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, a metal vacuum structure according to the present invention includes a getter that absorbs a gas released in the space in a space closed by an inner cylinder and an outer cylinder , after evacuating the exhaust hole, it seals the exhaust pores of the inner tube and the outer tube, the lower the low temperature thereof than the activation temperature of the getter is Shokusetsu one, activation of said the other getter In the metal vacuum structure in which a high-temperature object higher than the temperature comes into contact , the getters are arranged at substantially the center in the longitudinal direction of both the inner cylinder and the outer cylinder .
[0007]
In the metal vacuum structure, since a low-temperature object lower than the activation temperature of the getter is in contact with either side of the inner cylinder and the outer cylinder, a high-temperature object higher than the activation temperature of the getter is in contact with the opposite side , Even if the inner cylinder or outer cylinder on the high temperature side or the getter releases a gas such as hydrogen, the gas can be absorbed by the getter on the low temperature side. Therefore, it can prevent that the vacuum degree of the space between an inner cylinder and an outer cylinder falls, and can prevent that heat insulation performance falls. Further, since it is not necessary to use a getter having a high activation temperature according to the environment in which it is used, it is possible to prevent the vacuum structure itself from increasing in cost.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a vacuum heat insulating pipe 1 which is a metal vacuum structure according to the first embodiment of the present invention. The vacuum heat insulating pipe 1 includes an inner cylinder 2 that is a first metal member, an outer cylinder 3 that is a second metal member in which the inner cylinder 2 is disposed, and a connecting member 5 that connects them. In this embodiment, getters 10 </ b> A and 10 </ b> B are disposed on the outer surface of the inner cylinder 2 and the inner surface of the outer cylinder 3 in the space 6 closed by these components.
[0010]
The inner cylinder 2 and the outer cylinder 3 are made of a metal material having heat resistance that can withstand the environment (temperature) to be used, and stainless steel (SUS304) is used in this embodiment. In addition, the connection flange 4 which provided the attachment hole 4a with the predetermined space | interval is fixed to the both ends edge of the said outer cylinder 3 by welding.
[0011]
The connecting member 5 is an annular ring having a J-shaped cross section formed of the same metal material as the inner cylinder 2 and the outer cylinder 3. The connecting member 5 has an inner surface welded to the outer surface of the inner cylinder 2 and an outer surface welded to the inner surface of the outer cylinder 3. And it sets so that the difference amount of the elongation by the difference in the temperature added to the inner cylinder 2 and the outer cylinder 3 may be absorbed.
[0012]
The space 6 closed by the inner cylinder 2, the outer cylinder 3 and the connecting member 5 is evacuated to a vacuum state via the tip tube 7, and the tip tube 7 is sealed off. The tip tube 7 is fixed to an exhaust hole 3 a provided in the outer cylinder 3 via a base member 8. A cover 9 is attached to the base member 8.
[0013]
The getters 10A and 10B absorb the gas released from the metallic component members 2, 3, and 5 and released into the space 6, and the outer surface of the inner cylinder 2 by the fastener 11 similar to the conventional one. And, it is fixed at a substantially central position in the longitudinal direction on the inner surface of the outer cylinder 3. Here, this center position is the position where the heat is most distant and the lowest temperature is reached by heat conduction .
[0014]
Specifically, the getters 10A and 10B of the present embodiment are activated at a temperature of 400 ° C. to 500 ° C. and melted at a temperature of 900 ° C. or higher. As the getters 10A and 10B having such characteristics, for example, those obtained by hydrocrushing zirconium or titanium having a purity of 90% or more, preferably 99% or more, and containing 10,000 ppm or more of hydrogen are applied.
[0015]
Here, the zirconium or titanium is finely pulverized in an inert gas atmosphere such as Ar or He by mechanical means such as a stamp mill or a ball mill, so that the particle size of the powder is 30 to 250 mesh. In addition, if it is 30 mesh or less, the fluidity | liquidity of powder will be bad and shaping | molding will become difficult, and if it is 250 mesh or more, a specific surface area will become small and getter performance will fall remarkably. The finely pulverized zirconium powder or titanium powder is added with 0.5 to 1.0% of carbon as a lubricant , pressed in a die having a desired shape, or packed in a mold, and Ar, He, etc. Are molded into a desired shape under an inert gas atmosphere and sintered. The bulk specific gravity after molding is preferably 4 to 5.
[0016]
Next, the manufacturing method of the said vacuum heat insulation pipe 1 is demonstrated. Note that the getters 10A and 10B absorb sufficient hydrogen of 10,000 ppm or more due to hydrogenation in the manufacturing process, so that they accept free gas such as hydrogen released from the inner cylinder 2 and the outer cylinder 3 as they are. I can't. Therefore, dehydrogenation of the getters 10A and 10B is performed during the manufacturing process of the vacuum heat insulating pipe 1.
[0017]
Specifically, first, the outer cylinder 3 to which the inner cylinder 2 and the tip tube 7 are fixed is formed, respectively, and getters 10A and 10B are placed at predetermined positions on the outer surface of the inner cylinder 2 and the inner surface of the outer cylinder 3 via fasteners 11. To fix. And after arrange | positioning the connection member 5 to the outer surface of both ends of the inner cylinder 2, and joining these, the joined inner cylinder 2 and the connection member 5 are inserted in the outer cylinder 3, and it connects with the inner surface of both ends of the outer cylinder 3. The member 5 is joined to form a double-structured cylinder.
[0018]
Next, air is heated from the space 6 to be evacuated between the inner cylinder 2 and the outer cylinder 3 through the exhaust hole 3 a fixed to the outer cylinder 3 while heating the double cylinder at 250 to 600 ° C. for 3 minutes or more. The getters 10A and 10B are dehydrogenated while being discharged and decompressed. At this time, hydrogen (H), carbon monoxide (CO), and water (H ₂ O) are released from the inner cylinder 2, the outer cylinder 3, the connecting member 5, and the fastener 11. The contained hydrogen is released from the getters 10A and 10B.
[0019]
The getters 10A and 10B are activated when heated to 400 to 600 ° C. with a slight delay. Thereafter, the exhaust hole 3a (chip tube 7) is sealed, and after this sealing, hydrogen, carbon monoxide and water remaining in the space 6 between the inner cylinder 2 and the outer cylinder 3 are released. Absorbed by the activated getters 10A and 10B. As a result, the space 6 between the inner cylinder 2 and the outer cylinder 3 is maintained in a vacuum, and a high vacuum heat insulating pipe 1 is obtained.
[0020]
Next, use of the manufactured vacuum heat insulation pipe 1 is demonstrated. The vacuum heat insulating pipe 1 is used, for example, as an exhaust pipe for exhaust gas exhausted from an internal combustion engine such as an automobile or a motorcycle, or as a pipe for introducing cooling water to a predetermined part in a heating furnace.
[0021]
When used as an exhaust pipe of an internal combustion engine, high-temperature exhaust gas passes through the inside of the inner cylinder 2 through the vacuum insulation pipe 1, while low-temperature outside air comes into contact with the outside of the outer cylinder 3 and is applied to these temperatures. The difference is 400 ° C. or higher. The temperatures (heat) of the exhaust gas and the outside air are transmitted to the inner cylinder 2 and the outer cylinder 3, respectively, and are transmitted to the getters 10A and 10B disposed on them.
[0022]
Here, the temperature of the exhaust gas is higher than the activation temperature of the getters 10A and 10B and the heating temperature during manufacture. Therefore, the inner cylinder 2 releases further contained hydrogen, carbon monoxide and water, and the getter 10A further releases hydrogen contained therein as well as hydrogen absorbed after sealing.
[0023]
However, in the vacuum heat insulating pipe 1 of the present embodiment, another getter 10B is disposed in the outer cylinder 3 in contact with the outside air lower than the activation temperature of the getters 10A and 10B, so that the inner cylinder 2 and the getter 10A are released. The obtained hydrogen is absorbed by the getter 10B. Further, the carbon monoxide and water released by the inner cylinder 2 are absorbed by both getters 10A and 10B.
[0024]
On the other hand, when used as the cooling water introduction pipe of the heating furnace, the vacuum heat insulation pipe 1 is in contact with the high temperature atmosphere gas in the furnace outside the outer cylinder 3, while low temperature cooling water is inside the inner cylinder 2. The temperature difference which passes and is added to these is 400 degreeC or more like the above.
[0025]
When the temperature in the furnace is higher than the temperature at which the getters 10A and 10B are activated, the outer cylinder 3 releases further contained hydrogen, carbon monoxide and water, and the getter 10B absorbs hydrogen absorbed after sealing. Of course, the hydrogen contained therein is further released.
[0026]
However, since cooling water lower than the activation temperature of the getters 10A and 10B comes into contact with the inside of the inner cylinder 2, hydrogen released from the outer cylinder 3 and the getter 10B is absorbed by the getter 10A disposed in the inner cylinder 2. To do. Further, both the getters 10A and 10B absorb the carbon monoxide and water released by the outer cylinder 3.
[0027]
Thus, in the vacuum heat insulation pipe 1 of the present invention, since the getters 10A and 10B are arranged in both the inner cylinder 2 and the outer cylinder 3, the activation temperature of the getters 10A and 10B to be used is low. Even when used in an environment where the temperature is higher than the activation temperature, the getters 10A and 10B disposed on the low temperature side release the gas such as hydrogen released from the metal member on the high temperature side and the getters 10A and 10B disposed on the metal member. Can be absorbed. As a result, it is possible to prevent the vacuum degree of the space 6 between the inner cylinder 2 and the outer cylinder 3 from being lowered, and to prevent the heat insulation performance from being lowered. Specifically, in the vacuum heat insulating pipe 1 of this embodiment, the activation temperature of the getters 10A and 10B is 400 ° C. to 500 ° C., but the vacuum is reduced to a temperature of 900 ° C. at which the getters 10A and 10B on the high temperature side melt. It can be used while maintaining the state.
[0028]
Further, in the vacuum heat insulating pipe 1 of the present embodiment, the heat insulating performance is not deteriorated even when either the inside or the outside becomes a high temperature environment. For this reason, the single pipe 1 can cope with any use environment.
[0029]
The high temperature heat applied to the inner cylinder 2 or the outer cylinder 3 is transmitted from the inner cylinder 2 or the outer cylinder 3 to the outer cylinder 3 or the inner cylinder 2 on the low temperature side via the connecting member 5. However, in the vacuum heat insulating pipe 1 of the present embodiment, the getters 10A and 10B are disposed in the central portion farthest from the heat source, so that it is long for heat to be transmitted to the getters 10A and 10B disposed on the low temperature side. It takes time. Therefore, it is possible to suppress the situation where the low-temperature getters 10A and 10B cannot absorb the hydrogen released by the high-temperature getters 10A and 10B.
[0030]
The metal vacuum structure of the present invention is not limited to the configuration of the above embodiment .
[0031]
【The invention's effect】
As apparent from the above description, the metallic vacuum structure of the present invention, in those on either side of the inner cylinder and the outer cylinder is a low low-temperature material than the activation temperature of the getter is Shokusetsu, the getter both It is arranged. Therefore, while the use in environments where high hot product than the activation temperature of the getter is Shokusetsu, the hot side of the inner cylinder or the outer cylinder, and, getter disposed in the inner cylinder or the outer cylinder is a gas such as hydrogen Even when released, the gas can be absorbed by the low-temperature getter. Therefore, it can prevent that the vacuum degree of the space between an inner cylinder and an outer cylinder falls, and can prevent that heat insulation performance falls. Further, since it is not necessary to use a getter having a high activation temperature according to the environment in which it is used, it is possible to prevent the vacuum structure itself from increasing in cost.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a vacuum heat insulating pipe which is a metal vacuum structure of the present invention.
FIG. 2 is an exploded perspective view of the main part of FIG.
[Explanation of symbols]
1 ... Vacuum insulation pipe (metal vacuum structure)
2 ... Inner cylinder (first metal member)
3 ... Outer cylinder (second metal member)
3a ... exhaust hole 5 ... connecting member 6 ... space 7 ... tip tubes 10A, 10B ... getter 11 ... fastener

Claims (1)

In the space closed by the inner cylinder and the outer cylinder, a getter that absorbs the gas liberated in the space is disposed, and after exhausting the space from the exhaust hole, the exhaust hole is sealed, In the metal vacuum structure in which one of the inner cylinder and the outer cylinder is in contact with a low temperature object lower than the activation temperature of the getter, and the other is in contact with a high temperature object higher than the activation temperature of the getter ,
A metal vacuum structure characterized in that each of the getters is disposed at substantially the center in the longitudinal direction of both the inner cylinder and the outer cylinder .

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