Stock material or miscellaneous articles – Sheet including cover or casing – Filled with gas other than air; or under vacuum
Reexamination Certificate
2002-04-19
2004-12-07
Thomas, Alexander S. (Department: 1772)
Stock material or miscellaneous articles
Sheet including cover or casing
Filled with gas other than air; or under vacuum
C428S073000, C428S116000
Reexamination Certificate
active
06828001
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a vacuum heat-insulating panel having heat insulating and sound blocking features, and a method of manufacturing the same.
DESCRIPTION OF THE RELATED ART
Conventionally, there have been developed various panels and blocks having their respective inner spaces retained in vacuum to attain enhanced heat insulating capability. A vacuum heat-insulating block has its surface covered with flexible substance and its inside depressurized to provide a vacuum pack configuration, and such a configuration leaves the block unsatisfied in strength. To overcome this disadvantage, an improved vacuum block has its surface bonded with a rigid surface material to enhance its heat insulating property and rigidity. An improved heat-insulating panel is designed in a sandwich-like multi-layered configuration with a core element having a surface element superposed at its front and rear surfaces, retaining the inside of the core element in vacuum condition to attain enhanced properties of thermal break and strength.
A vacuum heat-insulating block or a vacuum panel does not transmit sound and thus advantageously has a sound blocking property and a heat insulating property. However, in an exemplary panel with the core element formed of continuous foam material which transmits sound, it has been found that heat and sound transmissibility levels are raised depending on the density of the core element, and therefore, it is desired to develop the core element for the vacuum heat-insulating panel that is reduced in density but enhanced in strength.
In view of obtaining the heat insulating and sound blocking features, the core element is desirably fabricated of a substance of low density. On the contrary, the core element must be sufficiently strong especially against compression and shearing forces, and for that purpose, it should desirably be fabricated of a substance of high density. It has long been desired to selectively obtain substances for the core element (e.g., continuous foam material) that meet such contradictory requirements.
Thus, a honeycomb core of assembled basaltiform or cylindrical cells is devised, which is suitable to be used as the core element of the vacuum heat-insulating panel because of its high compression and shearing strengths in contrast with relatively low density. The multi-layered panel having the core element in honeycomb structure and surface materials superposed at its front and rear sides is generally known as “honeycomb panel”, and especially, for such honeycomb panel used for structures, the honeycomb core serving as a core element is fabricated of a selected material excellent in shearing strength and shearing rigidity while the surface element is made of a material superior in tensile stress and compression strength, so as to implement increased flexural strength and rigidity.
In order to further add a heat insulating property to such structural honeycomb panel, the honeycomb core serving as the core element has its in side cells retained in vacuum condition and has its opposite sides superposed with surface materials into a multi-layered configuration so as to accomplish the improved vacuum heat-insulating panel.
Thus, the vacuum heat-insulating panel inherits the strength and rigidity from the honeycomb panel while retaining the inside of the honeycomb core in a vacuum condition.
This type of honeycomb cores can be roughly classified into those having air-permeable cells and those having non-permeable cells, depending on the material of which they are made.
With the air-permeable honeycomb core, all the cells in the panel serve as spaces defined separately but communicating with one another, and thus, a panel can be easily manufactured which has all the inside cells of the honeycomb core in vacuum condition.
With reference to
FIG. 12
, a method of manufacturing the vacuum heat-insulating honeycomb panel incorporated with an air-permeable honeycomb core will now be described.
Referring to FIG.
12
(
a
) illustrating a set-up procedure, an air-permeable honeycomb core
11
is mounted on a work table
20
, having its upper and lower surfaces superposed with bonding films
13
and surface materials
15
in this order. Simultaneously, edge columns
17
are positioned to prevent the ends of the honeycomb core from collapsing.
Referring to FIG.
12
(
b
) illustrating a heating, pressing, and bonding procedure, the upper and lower surfaces of the layered panel element are heated and pressed by a hot press
25
to fuse the bonding films
13
and consequently bond the surface materials to the honeycomb core
11
.
Referring to FIG.
12
(
c
) illustrating a depressurizing and sealing procedure, air is pumped out of the inside space of the honeycomb core
11
through a vacuum port
19
connected to a vacuum pump to depressurize the space. After the evacuation of air, the vacuum port
19
is sealed.
In an embodiment disclosed in Japanese Patent Unexamined Publication No. H11-280199 where an air-permeable honeycomb core has its opposite sides bonded to the surface material with the bonding films to depressurize the inside space into a vacuum condition, after air in the inside space of the core is pumped out into vacuum, the edge columns
17
support the honeycomb structure at the opposite edges to prevent the ends of the core from collapsing by the atmospheric pressure.
An example of depressurizing performed before the bonding procedure is shown in FIG.
13
.
Both the upper and lower ends
11
a
of the honeycomb core
11
sufficiently withstand compression by the atmospheric pressure, but lateral ends
11
b
of the honeycomb core collapse by the atmospheric pressure.
As has been described, the air-permeable design of honeycomb core and the process of developing a vacuum condition after bonding the surface materials thereto advantageously enable the whole core to be evacuated into vacuum, but due to the air-permeability of the cells, the vacuum condition of the whole panel is lost when even a part of the panel loses its air-tight seal, which results in the panel losing the heat insulating and sound blocking features. Additionally, after the layered elements are integrated into a panel, it is impossible to cut it into various shapes or to punch a hole there through. Thus, the panel must be created into a wide variety of dimensions and designs depending on various applications.
An embodiment incorporated with the non-permeable honeycomb core will now be described.
It is a basic requirement that the honeycomb core used for structural members should be rigid. However, if a heat insulating property is especially required, a non-metallic honeycomb is used due to its poor heat conductivity. Particularly, the non-metallic honeycomb core, when used for manufacturing a high-strength panel, is first bonded to other elements into a multi-layered panel element, and thereafter impregnated with fused resin solution while being under spreading and tensile forces to gain increased shearing rigidity, and hence, during such manufacturing procedure, the honeycomb core loses air-permeability.
In the vacuum heat-insulating panel incorporated with the non-permeable honeycomb core, the honeycomb core has its cells defined independent of one another, so the resultant panel would not lose its heat insulating and sound blocking properties even if apart of the panel is damaged to degrade air-tight sealing. Cutting the panel or punching a hole thereto causes the panel to merely locally lose its inherent properties, but advantageously, the panel, as a whole, still retains the preferable properties.
This enables the vacuum heat-insulating high-strength panel to be manufactured in large dimensions and then cut into pieces of required dimensions or to be provided with a hole, depending on applications.
However, there arises some problem with the procedure of evacuating the whole non-permeable honeycomb core into vacuum. Specifically, since the cells of the honeycomb configuration are defined independently, when pumping air out of all the cells to leave the in
Tokonabe Hideo
Umeda Katsuhiko
Jamco Corporation
Thomas Alexander S.
Westerman, Hattori, Daniels & Adrian , LLP.
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