Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal for a pipe – conduit – or cable
Reexamination Certificate
2000-02-11
2002-03-19
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal for a pipe, conduit, or cable
C277S608000, C277S611000, C277S612000, C277S626000, C277S647000
Reexamination Certificate
active
06357759
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to jacket seals, and in particularly to seals (gaskets) suitably used with pipes or containers which are internally evacuated of air.
In the field of semiconductor, it is desired to completely eliminate any foreign materials present in a product, to enhance vacuum and to make the inside of pipes for vacuum drawing to be cleaner in order to manufacture high-performance products capable of performing advanced technology functions. Accordingly, even in the case of seals for use in joints of pipes or the like for vacuum drawing, such a seal is required not to give off, from itself, gas or particles into the pipe.
In the case of using an O ring of rubber as a seal, the components of the rubber ring are emitted, by vacuum drawing, into a pipe in a gaseous form or in a particle form. Also, a gas outside the pipe permeates through the rubber and enters into the pipe. Accordingly, rubber O rings are unfit for vacuum seals. The rubber O ring is not suitably used where a fluid, which attacks rubber, flows through the pipe, either. On the other hand, an O ring of metal emits no foreign materials of the type described above. The metal O rings however, requires heavier clamping pressure to perform an effective seal function. It is therefore essential to provide a mechanism capable of achieving a heavy clamping pressure at joint portions of a vacuum apparatus. This, however, produces the problem that the apparatus itself increases in size. In order to enhance the clamping pressure, for example, the number of clamping bolts must be increased, which may cause some problems in construction that layout space for bolts cannot be reserved and that members being sealed hardly sustains the clamping pressure. Thus, the apparatus increases in size.
To cope with such a problem, as shown in
FIGS. 13 and 14
, a jacket seal, which emits no foreign material into a space
30
being sealed, which involves no gas permeation and which requires no heavy seal clamping pressure, is employed. In the jacket seal, an elastic member
1
having a cross section of circular shape is accommodated in a metal jacket
2
which has, at its outer peripheral surface, an opening portion
23
, and projections
25
and
25
having a cross section of triangular shape are annularly formed on surfaces
21
and
21
being squeezingly compressed (exterior surfaces of flange portions) of the metal jacket
2
, these surfaces
21
and
21
being in opposite relationship with seal surfaces of members being. sealed.
In such a jacket seal, an inner peripheral surface
24
and the being-compressed surfaces
21
and
21
are all formed of metal, so that inclusion of foreign materials into the being-sealed space
30
is unlikely to occur. Furthermore, the projection
25
of the being-compressed surface
21
has a vertex point which abuts against the seal surface of the being-sealed member and which is then crushed by seal clamping pressure to come into close contact with the seal surface of the being-sealed member. Meanwhile, the metal jacket
2
is deflected by seal clamping pressure such that the opening portion
23
is made narrower. At the same time, the elastic member
1
held in the metal jacket
2
also undergoes compressive deformation, as a result of which reaction force against the seal clamping pressure can be obtained from the metal jacket
2
and from the elastic member
1
. Accordingly, such a jacket seal makes it possible to obtain sufficient seal effects without the necessity of achieving a heavy clamping pressure.
In a conventional jacket seal, in order to obtain high seal performance with small clamping pressure, it is arranged such that the projection
25
having a cross section of triangular shape has a vertex point which is finished relatively sharp so that the projection
25
is easily crushed and small clamping pressure is concentrated on the vertex point to improve sealability. In addition, in order to hold down costs, an O ring of rubber superior in versatility is also used as the elastic member
1
that is accommodated in the metal jacket.
However, the performance of jacket seals may vary depending on the machining accuracy of the metal jacket
2
. For example, as shown in FIG.
16
(
a
), if the position of a vertex point T of the projection
25
formed on the being-compressed surface
21
of the metal jacket
2
in opposing relationship with the seal surface
32
of the being-sealed member, deviates from a centerline m in a cross section of the elastic member
1
accommodated in the metal jacket
2
, then proper reaction force will not be obtained from the elastic member
1
upon application of clamping pressure, so that a flange portion of the metal jacket
2
itself may distort to undergo plastic deformation, as shown in FIG.
16
(
b
). Accordingly, in some cases, a desired seal performance is not obtained. Moreover, once a jacket seal has undergone plastic deformation, it is impossible to reuse such a plastically-deformed seal, which means that when disassembling a pipe joint for the purpose of maintenance/inspection or the like, there is produced the problem that a new jacket seal must be prepared, which is uneconomical.
Moreover, the projection
25
, formed on the being-compressed surface
21
of the metal jacket
2
, is finished sharp pointed for the purpose of improving sealability. However, when the projection
25
is finished sharp pointed, a burr or a flash is created at an endmost portion of the projection
25
, which results in poor machining accuracy. Accordingly, when clamped, the projection
25
will not be crushed uniformly over its full length, and, as shown in
FIG. 15
, in the projection thus crushed, two sections are mixedly present. More specifically, one of the sections (indicated by solid line) results from the collapse of the end T of the projection
25
from its original position T′ prior to the crush toward P (the inside (central side) of the seal), while the other of the sections (indicated by broken line) results from the collapse of T from T′ toward R (the outside of the seal). Therefore a target seal performance cannot be achieved at a point of inflection where the direction, in which the projection
25
collapses, changes from the side P to the side R, and a phenomenon, in which there occurred a drop in the seal performance, was observed.
Accordingly, an object of the present invention is to provide solutions to these problems.
Moreover, another object of the present invention is to constantly achieve high seal performance without requiring high machining accuracy.
Furthermore, still another object of the present invention is to provide a jacket seal which is stable in quality and which can be reused.
SUMMARY OF THE INVENTION
In order to solve the above-described problem, the present invention discloses a jacket seal comprising (a) a metal jacket having an annular web portion and a pair of flange portions projecting outward from sides of the web portion, respectively, and (b) an elastic member accommodated in the metal jacket,
wherein the metal jacket includes a projection which is annularly formed at an exterior surface of each of the flange portions and which abuts against a seal surface of a member being sealed (i.e., a pipe or a container to be sealed), and
the elastic member includes a flat portion which abuts against an interior surface of each of the flange portions of the metal jacket.
In the jacket seal of the present invention, the flat portion is in surface-to-surface contact with a position of the interior surface of each of the flange portions of the metal jacket corresponding to the projection.
In the jacket seal of the present invention, the projection has a cross section of approximately triangular shape whose vertex angle is 50 degrees or more.
The present invention discloses a jacket seal comprising (a) a metal jacket having an annular web portion and a pair of flange portions projecting outward from sides of the web portion, respectively, and (b) an elastic member accommodated in the metal jac
Azuma Yoshio
Kariya Takahiro
Mitsui Takayoshi
Knight Anthony
Mitsubishi Cable Industries Ltd.
Nixon & Peabody LLP
Robinson Eric J.
Rodgers Matthew E.
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