Title: Shallow metallic s-seal
Abstract: A metallic seal is provided that concentrates the available load over a narrow band to produce a sealing dam over a sufficient width to minimize leakage on a molecular level. The metallic seal has a first annular end section with has a first annular sealing surface, a second annular end section with a second annular sealing surface and an annular center section extending between the first and second annular end sections to form a ring having a central passageway with a center longitudinal axis. The third annular section is frustoconical tube with the first and second annular end sections being contiguously arranged at opposite ends of the annular center section such that sealing loads applied substantially perpendicularly on the first and second annular sealing surfaces primarily deform due to torsional stress of the metallic seal.
Patent Number: 7,004,478 Issued on 02/28/2006 to Spence, et al.
| Inventors:
|
Spence; John Loyd (Severna Park, MD);
Rowland; Stephen B. (Laurel, MD)
|
| Assignee:
|
PerkinElmer Inc. (Wellesley, MA)
|
| Appl. No.:
|
005178 |
| Filed:
|
December 7, 2001 |
| Current U.S. Class: |
277/644; 277/626 |
| Current Intern'l Class: |
F16J 15/02 (20060101) |
| Field of Search: |
277/644,648,649,650,626
|
References Cited [Referenced By]
U.S. Patent Documents
| 3285632 | Nov., 1966 | Dunkle.
| |
| 3537733 | Nov., 1970 | Martin.
| |
| 3602532 | Aug., 1971 | Ehrenberg.
| |
| 3630553 | Dec., 1971 | Foulger.
| |
| 3754766 | Aug., 1973 | Asplund.
| |
| 3767216 | Oct., 1973 | Martin.
| |
| 4039741 | Aug., 1977 | Havens.
| |
| 4056682 | Nov., 1977 | Havens et al.
| |
| 4121843 | Oct., 1978 | Halling.
| |
| 4282643 | Aug., 1981 | Yamasaki et al.
| |
| 4395049 | Jul., 1983 | Schertler.
| |
| 4457523 | Jul., 1984 | Halling et al.
| |
| 4779901 | Oct., 1988 | Halling.
| |
| 4813692 | Mar., 1989 | Halling et al.
| |
| 4819973 | Apr., 1989 | Pegon.
| |
| 4854600 | Aug., 1989 | Halling et al.
| |
| 5176413 | Jan., 1993 | Westman.
| |
| 5222744 | Jun., 1993 | Dennys.
| |
| 5706787 | Jan., 1998 | Fujikawa.
| |
| 5716052 | Feb., 1998 | Swensen et al.
| |
| 5730445 | Mar., 1998 | Swensen et al.
| |
| 5954343 | Sep., 1999 | Sumida et al.
| |
| 6209884 | Apr., 2001 | Taudt.
| |
| 6619668 | Sep., 2003 | Pyre.
| |
| Foreign Patent Documents |
| 2036502 | Dec., 1970 | FR.
| |
| 2800147 | Apr., 2001 | FR.
| |
Primary Examiner: Pickard; Alison K.
Attorney, Agent or Firm: Shinjyu Global IP Counselors, LLP
Claims
What is claimed is:
1. A metallic seal comprising:
a first annular end section having a first annular sealing surface facing in
a first direction and lying in a first contact plane to contact a first member
for creating a first annular sealing dent therebetween, said first annular sealing
surface being formed on a convexly curved surface;
a second annular end section having a second annular sealing surface facing in
a second direction that is opposite to said first direction, and lying in a second
contact plane that is substantially parallel to said first contact plane to contact
a second member for creating a second annular sealing dam therebetween, said second
annular sealing surface being formed on a convexly curved surface; and
an annular center section extending between said first and second annular end
sections to form a ring having a central passageway with a center longitudinal
axis, said annular center section being frustoconically shaped with said first
and second annular end sections being contiguously arranged at opposite ends of
said annular center section such that sealing loads applied substantially perpendicularly
an said first and second annular sealing surfaces primarily deform said metallic
seal due to torsional stress of said metallic seal, said first and second annular
end sections and said annular center section being arranged to form an S-shaped
cross sectional profile,
said first and second sealing surfaces being spaced apart by a first distance
measured parallel to said center longitudinal axis that is substantially equal
to a second distance measured perpendicular to said center longitudinal axis between
said first and second sealing surfaces.
2. A metallic seal comprising:
a first annular end section having a first annular sealing surface facing in
a first direction and lying in a first contact plane to contact a first member
for creating a first annular sealing dam therebetween, said first annular sealing
surface being formed on a convexly curved surface;
a second annular end section having a second annular sealing surface facing in
a second direction that is opposite to said first direction, and lying in a second
contact plane that is substantially parallel to said first contact plane to contact
a second member for creating a second annular sealing dam therebetween, said second
annular sealing surface being formed on a convexly curved surface, each of said
convexly curved surfaces extending through an arc of about 60°; and
an annular center section extending between said first and second annular end
sections to form a ring having a central passageway with a center longitudinal
axis, said annular center section being frustoconically shaped with said first
and second annular end sections being contiguously arranged at opposite ends of
said annular center section such that sealing loads applied substantially perpendicularly
on said first and second annular sealing surfaces primarily deform said metallic
seal due to torsional stress of said metallic seal, said first and second annular
end sections and said annular center section being arranged to font an S-shaped
cross sectional profile.
3. The metallic seal according to claim 2, wherein
said annular center section has a slope of about 45° with respect to said
center longitudinal axis.
4. The metallic seal according to claim 3, wherein
said first and second sealing surfaces are spaced apart by a first distance measured
parallel to said center longitudinal axis that is substantially equal to a second
distance measured perpendicular to said center longitudinal axis between said first
and second sealing surfaces.
5. The metallic seal according to claim 2, wherein
said convexly curved surfaces extend from a free end of said seal to said annular
center section.
6. The metallic seal according to claim 5, wherein
said annular center section has a slope of about 45° with respect to said
center longitudinal axis.
7. The metallic seal according to claim 6, wherein said annular center section
has a straight cross-sectional profile.
8. A metallic seal comprising:
a first annular end section having a first annular sealing surface facing in
a first axial direction and lying in a first contact plane to contact a first member
for creating a first annular sealing dam therebetween, said first annular sealing
surface being formed on a first convexly curved surface at a location that is spaced
from a first free end of said first annular end section;
a second annular end section having a second annular sealing surface facing in
a second axial direction that is opposite to said first axial direction, and lying
in a second contact plane that is substantially parallel to said first contact
plane to contact a second member for creating a second annular sealing dam therebetween,
said second annular sealing surface being formed on a second convexly curved surface
at a location that is spaced from a second free end of said second annular end
section; and
an annular center section extending between said first and second annular end
sections to form a ring having a central passageway with a center longitudinal
axis, said annular center section being frustoconically shaped with said first
and second annular end sections being contiguously arranged at opposite ends of
said annular center section such that sealing loads applied substantially perpendicularly
on said first and second annular sealing surfaces primarily deform said metallic
seal due to torsional stress of said metallic seal, said first and second annular
end sections and said annular center section being arranged to form an S-shaped
cross sectional profile with said first and second annular sealing surfaces being
located closer to midpoints of said first and second convexly curved surfaces than
to said opposite ends of said annular center section and said first and second
free ends, respectively,
said first and second sealing surfaces being spaced apart by a first: distance
measured parallel to said center longitudinal axis that is substantially equal
to a second distance measured perpendicular to said center longitudinal axis between
said first and second sealing surfaces, said first and second contact planes of
said first and second sealing surfaces being arranged substantially perpendicular
to said center longitudinal axis.
9. A metallic seal comprising:
a first annular end section having a first annular sealing surface facing in
a first radial direction and lying in a first contact plane to contact a first
member for creating a first annular sealing dam therebetween, said first annular
sealing surface being formed on a first convexly curved surface at a location that
is spaced from a first free end of said first annular end section;
a second annular end section having a second annular sealing surface facing in
a second radial direction that is opposite to said first direction, and lying in
a second contact plane that is substantially parallel to said first contact plane
to contact a second member for creating a second annular sealing dam therebetween,
said second annular sealing surface being farmed on a second convexly curved surface
at a location that is spaced from a second free end of said second annular end
section, each of said first and second convexly curved surfaces extending through
an arc of about 60°; and
an annular center section extending between said first and second annular end
sections to form a ring having a central passageway with a center longitudinal
axis, said annular center section being frustoconically shaped with said first
and second annular end sections being contiguously arranged at opposite ends of
said annular center section such that sealing loads applied substantially perpendicularly
on said first and second annular sealing surfaces primarily deform said metallic
seal due to torsional stress of said metallic seal, said first and second annular
end sections and said annular center section being arranged to form an S-shaped
cross sectional profile with said first and second annular sealing surfaces being
located closer to midpoints of said first and second convexly curved surfaces than
to said opposite ends of said annular center section and said first and second
free ends, respectively,
said first and second contact planes of said first and second sealing surfaces
being arranged substantially parallel to said center longitudinal axis.
10. A metallic seal comprising:
a first annular end section having a first annular sealing surface facing in
a first direction and lying in a first contact plane to contact a first member
for creating a first annular sealing dam therebetween, said first annular sealing
surface being formed on a convexly curved surface;
a second annular end section having a second annular sealing surface facing in
a second direction that is opposite to said first direction, and lying in a second
contact plane that is substantially parallel to said first contact plane to contact
a second member for creating a second annular scaling dam therebetween, said second
annular sealing surface being formed on a convexly curved surface; and
an annular center section extending between said first and second annular end
sections to form a ring having a central passageway with a center longitudinal
axis, said annular center section having a slope of about 45° with respect
to said center longitudinal axis, said annular center section being frustoconically
shaped with said first and second annular end sections being contiguously arranged
at opposite ends of said annular center section such that sealing loads applied
substantially perpendicularly on said first and second annular sealing surfaces
primarily deform said metallic seal due to torsional stress of said metallic seal,
said first and second annular end sections and said annular center section being
arranged to form an S-shaped cross sectional profile.
11. The metallic seal according to claim 10, wherein said first and second directions
of said first and second sealing surfaces are arranged substantially parallel to
said center longitudinal axis.
12. The metallic seal according to claim 10, wherein said first and second directions
of said first and second sealing surfaces are arranged to face substantially radially
relative to said center longitudinal axis.
13. The metallic seal according to claim 10, wherein
said seal is formed of a corrosion resistant alloy.
14. The metallic seal according to claim 10, wherein
said seal is formed of a material selected from the group of nickel based alloys,
copper based alloys, tin, aluminum based alloys and stainless steel.
15. The metallic seal according to claim 10, wherein
said first and second annular end sections have substantially identical cross
sectional profiles that are inverted.
16. A metallic seal comprising:
a first annular end section having a first annular sealing surface facing in
a first direction and lying in a first contact plane to contact a first member
for creating a first annular sealing dam therebetween, said first annular sealing
surface being formed on a first convexly curved surface at a location that is spaced
from a first free end of said first annular end section;
a second annular end section having a second annular sealing surface facing in
a second direction that is opposite to said first direction, and lying in a second
contact plane that is substantially parallel to said first contact plane to contact
a second member for creating a second annular sealing dam therebetween, said second
annular sealing surface being formed on a second convexly curved surface at a location
that is spaced from a second free end of said second annular end section, each
of said first and second convexly curved surfaces extending through an arc of about
60°; and
an annular center section extending between said first and second annular end
sections to form a ring having a central passageway with a center longitudinal
axis, said annular center section being frustoconically shaped with said first
and second annular end sections being contiguously arranged at opposite ends of
said annular center section such that sealing loads applied substantially perpendicularly
on said first and second annular sealing surfaces primarily deform said metallic
seal due to torsional stress of said metallic seal, said first and second annular
end sections and said annular center section being arranged to form an S-shaped
cross sectional profile with said first and second annular sealing surfaces being
located closer to midpoints of said first and second convexly curved surfaces than
to said first and second free ends, respectively.
17. A metallic seal comprising:
a first annular end section having a first annular sealing surface facing in
a first direction and lying in a first contact plane to contact a first member
for creating a first annular sealing dam therebetween, said first annular sealing
surface being formed on a first convexly curved surface at a location that is spaced
from a first free end of said first annular end section;
a second annular end section having a second annular sealing surface facing in
a second direction that is opposite to said first direction, and lying in a second
contact plane that is substantially parallel to said first contact plane to contact
a second member for creating a second annular sealing dam therebetween, said second
annular sealing surface being formed on a second convexly curved surface at a location
that is spaced from a second free end of said second annular end section; and
an annular center section extending between said first and second annular end
sections to form a ring having a central passageway with a center longitudinal
axis, said annular center section having a slope of about 45° with respect
to said center longitudinal axis, said annular center section being frustoconically
shaped with said first and second annular end sections being contiguously arranged
at opposite ends of said annular center section such that sealing loads applied
substantially perpendicularly on said first and second annular sealing surfaces
primarily deform said metallic seal due to torsional stress of said metallic seal,
said first and second annular end sections and said annular center section being
arranged to form an S-shaped cross sectional profile with said first and second
annular sealing surfaces being located closer to midpoints of said first and second
convexly curved surfaces than to said first and second free ends, respectively.
18. A metallic seal comprising:
a first annular end section having a first annular sealing surface facing in
a first direction and lying in a first contact plane to contact a first member
for creating a first annular sealing dam therebetween, said first annular sealing
surface being formed on a first convexly curved surface at a location that is spaced
from a first fret end of said first annular end section;
a second annular end section having a second annular sealing surface facing in
a second direction that is opposite to said first direction, and lying in a second
contact plane that is substantially parallel to said first contact plane to contact
a second member for creating a second annular sealing dam therebetween, said second
annular sealing surface being formed on a second convexly curved surface at a location
chat is spaced from a second free end of said second annular end section; and
an annular center section extending between said first and second annular end
sections to form a ring having a central passageway with a center longitudinal
axis, said annular center section being frustoconically shaped with said first
and second annular end sections being contiguously arranged at opposite ends of
said annular center section such that sealing loads applied substantially perpendicularly
on said first and second annular sealing surfaces primarily deform said metallic
seal due to torsional stress of said metallic seal, said first and second annular
end sections and said annular center section being arranged to form an S-shaped
cross sectional profile with said first and second annular sealing surfaces being
located closer to midpoints of said first and second convexly curved surfaces than
to said first and second free ends, respectively,
said first and second sealing surfaces being spaced apart by a first distance
measured parallel to said center longitudinal axis that is substantially equal
to a second distance measured perpendicular to said center longitudinal axis between
said first and second sealing surfaces.
19. An axial metallic face seal comprising:
a first annular end section having a first annular sealing surface facing in
a first direction and lying in a first contact plane to contact a first member
for creating a first annular sealing dam therebetween, said first annular sealing
surface being formed on a convexly curved surface extending through an arc to form
a first free end that is spaced from said first annular scaling surface;
a second annular end section having a second annular sealing surface facing in
a second direction that is opposite to said first direction, and lying in a second
contact plane that is substantially parallel to said first contact plane to contact
a second member for creating a second annular sealing dam therebetween, said second
annular sealing surface being formed on a convexly curved surface extending through
an arc to form a second free end that is spaced from said second annular sealing
surface; and
an annular center section extending between said first and second annular end
sections to form a ring having a central passageway with a center longitudinal
axis that is substantially perpendicular to said first and second annular scaling
surfaces, said annular center section being frustoconically shaped with said first
and second annular end sections being contiguously arranged at opposite ends of
said annular center section such that sealing loads applied substantially perpendicularly
on said first and second annular sealing surfaces primarily deform said metallic
seal due to torsional stress of said metallic seal,
said first and second annular end sections and said annular center section being
arranged to form an S-shaped cross sectional profile with said annular center section
having a slope that is not greater than 45° with respect to said first and
second contact planes.
20. The axial metallic face seal according to claim 19, wherein
said first and second annular end sections have substantially identical cross
sectional profiles that are inverted.
21. The axial metallic face seal according to claim 19, wherein
said annular center section has a straight cross-sectional profile.
22. An axial metallic face seal comprising:
a first annular end section having a first annular sealing surface facing in
a first direction and lying in a first contact plane to contact a first member
for creating a first annular sealing dam therebetween, said first annular sealing
surface being formed on a convexly curved surface extending through an arc to form
a first free end that is spaced from said first annular scaling surface;
a second annular end section having a second annular sealing surface facing in
a second direction that is opposite to said first direction, and lying in a second
contact plane that is substantially parallel to said first contact plane to contact
a second member for creating a second annular sealing dam therebetween, said second
annular sealing surface being formed an a convexly curved surface extending through
an arc to form a second free end that is spaced from said second annular sealing
surface; and
an annular center section extending between said first and second annular end
sections to form a ring having a central passageway with a center longitudinal
axis that is substantially perpendicular to said first and second annular sealing
surfaces, said annular center section being frustoconically shaped with said first
and second annular end sections being contiguously arranged at opposite ends of
said annular center section such that sealing loads applied substantially perpendicularly
on said first and second annular sealing surfaces primarily deform said metallic
seal due to torsional stress of said metallic seal,
said first and second annular end sections and said annular center section being
arranged to form an S-shaped cross sectional profile with said first and second
sealing surfaces being spaced apart by a first axial distance measured parallel
to said center longitudinal axis that is smaller than a second radial distance
measured perpendicular to said center longitudinal axis between said first and
second sealing surfaces.
23. The axial metallic face seal according to claim 22, wherein
said first and second annular end sections have substantially identical cross
sectional profiles that are inverted.
24. The axial metallic face seal according to claim 22, wherein
said annular center section has a straight cross-sectional profile.
25. A metallic seal comprising:
a first annular end section having a first annular sealing surface facing in
a first direction to contact a first member for creating a first annular sealing
dam therebetween, said first annular sealing surface being formed on a convexly
curved surface extending through an arc to form a first free end that is spaced
from said first annular sealing surface;
a second annular end section having a second annular sealing surface facing in
a second direction that is opposite to said first direction to contact a second
member for creating a second annular sealing dam therebetween that is substantially
parallel to said first annular sealing dam, said second annular sealing surface
being formed on a convexly curved surface extending through an arc to form a second
free end that is spaced from said second annular sealing surface; and
an annular center section extending between said first and second annular end
sections to form a ring having a central passageway with a center longitudinal
axis, said annular center section being frustoconically shaped with said first
and second annular end sections being contiguously arranged at opposite ends of
said annular center section such that sealing loads applied substantially perpendicularly
on said first and second annular sealing surfaces primarily deform said metallic
seal due to torsional stress of said metallic seal,
said first and second annular end sections and said annular center section being
arranged to form an S-shaped cross sectional profile with said first and second
sealing surfaces being spaced apart by a first distance measured along said first
and second directions that is smaller than a second distance measured perpendicular
to said first and second directions, said annular center section being inclined
at an angle relative to said first and second sealing dams, with said angle being
closer to forty-five degrees than zero degrees.
26. The metallic seal according to claim 25, wherein
said first and second annular end sections have substantially identical cross
sectional profiles that are inverted.
27. The metallic seal according to claim 25, wherein
said annular center section has a straight cross-sectional profile.
28. The metallic seal according to claim 25, wherein
said first and second directions are substantially parallel to said center longitudinal
axis such that said metallic scal is an axial face seal.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to a metallic seal for creating a seal between
a pair of members. More specifically, the present invention relates to a seal that
provides a highly reliable seal by concentrating the available load over a narrow
band (small sealing area equaling high contact stress) to produce a high quality
sealing dam over a sufficient width to minimize leakage on a molecular level.
2. Background Information
A typical static seal assembly has a first member with a first mating surface,
an annular seal of suitable sealing material (e.g., metal O-ring), and a second
member with a second mating surface. A mechanical load is applied to the seal through
the first and second mating surfaces of the members. Typically, the mechanical
load is created by torquing down a multitude of fasteners such that a displacement,
also known as compression, occurs between the sealing surfaces. The net loading
of the contact surfaces creates the two sealing dams.
The low leakage requirement can be achieved by compressing a solid metal ring
of rectangular cross-section with a sufficient force. One problem with a solid
metal ring is that the force created could be of sufficient magnitude to cause
plastic deformation of the mating surfaces of the members. This plastic deformation
of the mating surface is called brinelling. Once brinelled, the probability of
proper resealing is drastically reduced without first repairing the damaged sealing surfaces.
The design requirements for static sealing therefore requires an optimum load
level and flexibility. A good static seal when compressed must be able to generate
load levels large enough to seal, but not large enough to brinell the cavity surfaces.
Currently, there are many types of metallic seals in the prior art.
The metallic "O" rings were an early effort to meet these conflicting design
requirements. However, the resiliency of this type of seal is rather limited because
the "O" ring, whether solid or hollow, is usually too stiff, and is inherently
expensive. The development of the C-shaped seal was an improvement to the "O" ring.
In particular, by simply discarding a portion of the "O", the hoop restraint of
the seal is greatly reduced and the seal becomes more flexible. However, the basic
"C" seals typically cannot reach the desirable standard vacuum level of 1×10e
-9
cc/sec He leakage rate or better without modification and without being coated
with very soft plating materials. Some previous C-shaped seals have been designed
to provide this level of seal integrity.
In addition to typical "C" seals, other prior seals include spring-energized
"C"
seals, spring-energized "C" seals with triangular feature (Delta-seal), deformable
metallic gaskets, E-seals with single or multiple convolutions. Some of these previous
designs can provide the level of seal integrity provided by the disclosed device
at comparable load levels or physical restraints.
Examples of these prior sealing rings are disclosed in U.S. Pat. No. 4,813,692
and U.S. Pat. No. 4,854,600. However, the seals of these two patent address semi-dynamic
applications where the two sealing surfaces are moving relative to each other.
These patents are associated with larger cross sections and the method of deformation
uses both axial bending and torsion.
In view of the above, it will be apparent to those skilled in the art that there
exists a need for improved metallic sealing rings with optimized sealing areas
that can be used at high temperatures and pressures while providing high reliability
and pressure tight sealing. This invention addresses this need in the art as well
as other needs, which will become apparent to those skilled in the art once given
this disclosure.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a highly reliable metallic
seal that is relatively inexpensive to manufacture.
Another object of the present invention is to provide a metallic seal, which
has geometrically simple cross sections, and can be manufactured with existing
equipment in large quantities with tight tolerances.
Still another object of the present invention is to provide a highly reliable
metallic seal, which concentrates the available load over a narrow band which minimizes
the required load to compress the seal by optimizing the sealing dam width.
Yet another object of the present invention is to provide a metallic seal in
which the seal dam does not significantly shift during compression of the seal.
Another object of the present invention is to provide a metallic seal which
has a leakage rate of less than 1×10e
-9 cc/sec He leakage rate
or better.
The foregoing objects can basically be attained by providing a metallic seal
that concentrates the available load over a narrow band to produce a sealing dam
over a sufficient width to minimize leakage while optimizing the load required
to compress the seal. The metallic seal comprises a first annular end section,
a second annular end section and an annular center section. The first annular end
section has a first annular sealing surface facing in a first direction and lying
in a first plane to contact a first member for creating a first annular sealing
dam therebetween. The second annular end section has a second annular sealing surface
facing in a second direction that is opposite to the first axial direction, and
lying in a second plane that is substantially parallel to the first plane to contact
a second member for creating a second annular sealing dam therebetween. The annular
center section extends between the first and second annular end sections to form
a ring having a central passageway with a center longitudinal axis. The third annular
section is frustoconical tube with the first and second annular end sections being
contiguously arranged at opposite ends of the annular center section such that
sealing loads applied substantially perpendicularly on the first and second annular
sealing surfaces primarily deform due to torsional stress of the metallic seal.
These and other objects, features, aspects and advantages of the present invention
will become apparent to those skilled in the art from the following detailed description,
which, taken in conjunction with the annexed drawings, discloses a preferred embodiment
of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to the attached drawings which form a part of this original disclosure:
FIG. 1 is a side elevational view of a shallow metallic seal in accordance with
a first embodiment of the present invention, with the thickness of the seal exaggerated
for purposes of illustration;
FIG. 2 is a top plan view of the shallow metallic seal illustrated in FIG. 1;
FIG. 3 is a cross-sectional view of the shallow metallic seal illustrated in
FIGS. 1 and 2, as seen along section line 3—3 of FIG. 2;
FIG. 4 is an enlarged cross-sectional profile of the shallow metallic seal illustrated
in FIGS. 1-3 prior to compression of the metallic seal, i.e., unloaded;
FIG. 5 is an exploded, longitudinal cross-sectional view of the shallow metallic
seal illustrated in FIGS. 1-4 together with a seal assembly having a pair of mating
members which are coupled together by fasteners to axially compress the metallic
seal for creating an annular seal therebetween;
FIG. 6 is a longitudinal cross-sectional view, similar to FIG. 5, of the mating
members and the metallic seal, but after the mating members have been coupled together
by the fasteners to compress the metallic seal for creating an annular seal therebetween; and
FIG. 7 is a longitudinal cross-sectional view of a shallow metallic seal according
to a second embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Initially referring to FIGS. 1-4, a shallow metallic seal
10 in
accordance with a first embodiment of the present invention is illustrated. The
shallow metallic seal
10 is illustrated as being circular. However, it will
be apparent to those skilled in the art from this disclosure that the shallow metallic
seal
10 could have other types of non-circular ring shapes and can also
be produced in a variety of heights. Moreover, the thickness of the metallic seal
10 in the attached drawings has been exaggerated for purposes of illustration.
The purpose of the metallic seal
10 is to provide a seal between two opposing
members, e.g., either metal to metal, metal to ceramic, ceramic to ceramic, or
any appropriate combination of materials commonly used in critical fluid and/or
gas sealing. Additionally, the metallic seal
10 can be used between flanges
or components for any fluid control or pneumatic application. The metallic seal
10 will most typically be used in a groove, counterbore or between relatively
flat surfaces providing a fixed separation of the components to be sealed. The
metallic seal
10 can be produced in circular or non-circular configurations
and may also be produced in a variety of heights.
As explained below in more detail, the shallow metallic seal
10 of the
present invention provides highly reliable sealing between two members by concentrating
the available load over a narrow band (small surface area equaling high contact
stress). Theses narrow sealing bands or surfaces produce a high quality sealing
dam over a sufficient width to minimize leakage on a molecular level. By minimizing
the seal dam widths over which the intimate contact between seal and mating surfaces
is needed, a high performance seal can be achieved without high compression loads.
In other words, the shallow metallic seal
10 of the present invention allows
its substantially parallel surfaces of the seal
10 to be in intimate contact
with the two cavity faces, resulting in a controlled contact stress (load divided
by the area of the annulus).
The shallow metallic seal
10 of the present invention is designed to be
used in to a wide range of sealing performance. The shallow metallic seal
10
of the present invention is especially applicable to the semiconductor equipment
industry, the vacuum equipment industry, the data storage device industry, or any
other industry where high reliability and/or extremely tight sealing (1×10e
-9
cc/sec He leakage rate or better) is required. The shallow metallic seal
10 of the present invention is also applicable anywhere that the basic configuration
lends itself to the sealing gland dimensions or the available bolt loading. For
example, the shallow metallic seal
10 can be used in a wide variety of applications
required in the Ultra High Vacuum (UHV) industry, the Aerospace, the Power Generation
industry and any other industry that requires the above stated functionality.
In particular, the shallow metallic seal
10 provides high pressure, high
temperature sealing with rates of 0.01 SCFM per inch of diameter to high reliability
and pressure tight with rates less than 1×10e
-9 cc/sec. The shallow
metallic seal
10 of the present invention is designed to perform at wide
range of force to compression or pounds per circumferential inch (PCI).
The shallow metallic seal
10 has a uniform cross sectional profile as
seen in FIG. 4. The term "cross-sectional profile" as used herein and in the claims
refers to a partial cross sectional shape of a portion of an annular seal as defined
by a longitudinal plane passing through only one point of the annular seal.
The shallow metallic seal
10 is constructed of a ductile alloy that is
pressed worked to form an annular member that has a cross sectional profile as
seen in FIG. 4. For example, the base material of the seal
10 is constructed
of a ductile alloy or metallic element such as tin, nickel, aluminum, copper, stainless
steel, Inconel and other nickel based alloys that improve seal integrity. Preferably,
the base material of the seal
10 is formed of a corrosion resistant alloy
that is selected from the group of nickel based alloys, copper based alloys, tin,
aluminum based alloys and stainless steel. Optionally, a softer ductile coating
could also be employed over the base material (ductile alloy). Examples of such
ductile coatings include, but not limited to, tin, aluminum, nickel indium, silver,
PFA, PTFE, etc. The ductile coating preferably has a thickness between about 0.001
inch and 0.006 inch. This ductile coating can cover the entire seal surfaces or
can be located only at the sealing surfaces. Other metal elements and non-metallic
compounds can be employed as well for the coating.
The shallow metallic seal
10 allows for seal cavity tolerances by designing
the seal stiffness to be acceptable over the combined tolerance range of the cavity
plus the seal. By designing the seal's cross-sectional profile as shown in FIG.
4, the deflection of the section is controlled. By varying the cross section (thickness,
radius of curvature at the seal interface, angle, height and radial width) the
load can be designed such that the seal will function in a variety of seal gland
depths, and with different coatings, each with their own specific yield strengths,
i.e. requiring more or less load to create a condition whereby the coating plastically
deforms over a given width.
As seen in FIGS. 5 and 6, a sealing assembly
12 in accordance with a first
embodiment of the present invention is diagrammatically illustrated to show the
metallic seal
10 being used. More specifically, the seal assembly
12
includes a first member
14, with a first mating or contact surface
16
and a second member
18 having a second mating or contact surface
20
for contacting the seal
10. The first and second members
14 and
18
are coupled together by a plurality of fasteners or bolts
22. The first
and second members
14 and
18 can be any two members or devices that
need a seal there between. Thus, the first and second members
14 and
18
are not illustrated with any particular structure.
For example, a variant of the metallic seal
10 can be constructed such
that an effective, low cost seal can be achieved for high temperature and/or high
pressure pneumatic applications. This variant can be constructed in a similar manner
as the high leak integrity version illustrated herewith.
The shallow metallic seal
10 is a one-piece, unitary member formed from
a single sheet material. Optionally, the metallic seal
10 can have a soft
coating over lying the base material. Basically, the cross-sectional profile of
the shallow metallic seal
10 can be divided into three annular sections
three annular section, i.e., a first annular end section
31, a second annular
end section
32 and a third annular center section
33. In the illustrated
embodiment, the first and second annular end sections
31 and
32 have
curved cross-sectional profiles, while the third annular center section
33
has a straight cross-sectional profile. Thus, the annular sections
31-
33
are configured to form a somewhat S-shaped cross section. This S-shaped cross section
is preferably uniform along the entire circumference of the metallic seal
10.
In the illustrated embodiment, the third annular center section
33 is a
frustoconical section. However, the third annular center section
33 can
have a curved cross-sectional profile and be a non-circular section viewed in the
axial direction. In any event, the third annular center section
33 is frustoconically
shaped. The term "frustoconically shaped" as used herein and in the claims refers
to an annular section having first and second annular ends with one of the ends
having a diameter or transverse dimension that is larger than the diameter or transverse
dimension of the other end and the annular section between the first and second
annular ends be non-undulated.
The first annular end section
31 has a first annular sealing surface
34
facing in a first axial direction A
1 and lying in a first flat contact
plane P
1. The first annular sealing surface
34 contacts the first
contact surface
16 of the first member
14 for creating a first annular
sealing dam D
1 therebetween. The second annular end section
32
has a second annular sealing surface
36 facing in a second axial direction
A
2 that is opposite to the first axial direction A
1, and
lies in a second flat contact plane P
2 that is substantially parallel
to the first flat contact plane P
1. The second annular sealing surface
36 contacts the second contact surface
20 of the second member
18
for creating a second annular sealing dam D
2 therebetween. The annular
center section
33 extends between the first and second annular end sections
31 and
32 to form a ring having a central passageway
38 with
a center longitudinal axis C.
The first and second sealing surfaces
34 and
36 are preferably
convexly curved surfaces with identical curvatures that extend through an arc α
of about 60° as seen in FIG. 4. In other words, the first and second sealing
surfaces
34 and
36 are basically annular sealing lines S
1
and S
2 with no radial width prior to compression of the seal
10.
As seen in FIG. 4. the annular sealing lines S
1 and S
2 are
located closer to midpoints M
1 and M
2 of the first and second
sealing surfaces
34 and
36, respectively, than to either of the end
points of the first and second sealing surfaces
34 and
36. By tightening
the fasteners
22, the metallic seal
10 is loaded, and thus, compressed
to plastically deform the seal primarily through torsion and create the pair of
annular seal dams D
1 and D
2 between the metallic seal
10
and the first and second members
14 and
18. Deformation of the metallic
seal
10 is about 10% to 25% of the axial height of the seal
10 between
its sealing surfaces
34 and
36. Once the seal
10 is compressed,
the first and second sealing surfaces
34 and
36 are deformed to form
flat sealing surfaces that correspond to the first and second annular sealing dams
D
1 and D
2. The minimum effective widths of first and second
annular sealing dams D
1 and D
2 of the first and second sealing
surfaces
34 and
36 lies within the range of about 0.005 inch to about
0.040 inch.
The first and second sealing surfaces
34 and
36 are spaced apart
by a first distance or height d
1 measured parallel to the center longitudinal
axis C that is smaller than a second distance (d
2) measured perpendicular
to the center longitudinal axis C between the first and second sealing surfaces
34 and
36. Thus, the annular center section
33 has a slope
that is not greater than 45° with respect to the first and second contact
planes P
1 and P
2 based on the geometry of right triangles
(i.e., the Pythagorean theorem). However, in the illustrated embodiment, the first
distance d
1 is substantially equal to a second distance d
2as
best seen in FIG. 4. Accordingly, the slope or incline of the annular center section
33 with respect to the first and second contact planes P
1 and
P
2 is closer to forty-five derees than zero degrees, as seen in FIGS. 3-6.
The third annular section
33 is a frustoconical tube. The first and second
annular end sections
31 and
32 are contiguously arranged at opposite
axial ends of the annular center section
33 such that sealing loads applied
substantially perpendicularly on the first and second annular sealing surfaces
34 and
36 primarily deform due to torsional stress of the metallic
seal
10. In other words, the metallic seal
10 is deform less than
50% by collapsing or axial being such as in the S-shaped seals disclosed in U.S.
Pat. Nos. 4,813,692 and 4,854,600. Preferably, the metallic seal
10 only
collapses or bends axially by about 20%. The annular center section
33 preferably
slopes about 45° relative to the first and second planes Pand P
2
in the illustrated embodiment, as best seen in FIG. 6.
The geometric and dimensional characteristics of seal
10 can be particularly
seen in FIG. 4. Referring initially to FIG. 2, the outer diameter of seal
10
can be any desired shape depending upon the application of seal
10, i.e.,
there is no limit to its outer diameter. The inner diameter of seal
10 should
be at least about 0.150 inch or greater. The free axial height d
1 of
seal
10 is typically between about 0.030 inch to about 0.250 inch. In one
example of the seal
10, the height d
1 is 0.035 inch, the outer
diameter is 0.315 inch, and the inner diameter is 0.245 inch.
In this embodiment, the first and second directions A
1 and A
2
of the first and second sealing surfaces
34 and
36 face in
directions that are substantially parallel to the center longitudinal axis C. Alternatively,
as seen in FIG. 7, a seal
110 is illustrated having the first and second
sealing surfaces
134 and
136 facing substantially perpendicular to
the center longitudinal axis C. In other words, the first and second sealing surfaces
134 and
136 are concentric sealing surfaces that face either towards
or away from the center longitudinal axis C. The metallic seal
110 is nearly
identical to seal
10, discussed above, except that for the cross section
as been rotated. In view of the similarities between seal
110 and seal
10,
discussed above, seal
110 will not be discussed or illustrated in detail
herein. Basically, the metallic seal
110 has a first annular end section
131, a second annular end section
132 and an annular center section
133.
Although only a portion of metallic seal
110 is illustrated herein,
it will be apparent to those skilled in the art from this disclosure that seal
110 is a continuous ring which can be either circular or non-circular. Preferably,
the cross-section of the seal
110 is uniform.
The terms of degree such as "substantially", "about" and "approximately" as used
herein mean a reasonable amount of deviation of the modified term such that the
end result is not significantly changed. These terms should be construed as including
a deviation of at least ±5% of the modified term if this deviation would not
negate the meaning of the word it modifies.
While only selected embodiments have been chosen to illustrate the present
invention, it will be apparent to those skilled in the art from this disclosure
that various changes and modifications can be made herein without departing from
the scope of the invention as defined in the appended claims. Possible variations
of the illustrated the seal
10 include a range of diameters, shapes, heights,
coatings, base materials chosen for coefficient of thermal expansion matches, pressure
or vacuum sealing, sealing any fluid by choosing compatible materials, or any other
variation typically used to configure the seal
10 for a given application.
Another advantage of the cross section is the ability to seal on the inner and
outer diameters and may be extended to other uses and industries. Furthermore,
the foregoing description of the embodiments according to the present invention
are provided for illustration only, and not for the purpose of limiting the invention
as defined by the appended claims and their equivalents.
*
