Low load seal

Details Low load seal Low load seal

2000-04-11

2003-02-25

Browne, Lynne H. (Department: 3677)

Seal for a joint or juncture

Seal between fixed parts or static contact against...

Contact seal for other than internal combustion engine, or...

C277S644000, C277S641000, C277S549000, C277S551000, C277S552000, C277S560000, C277S566000, C277S626000

Reexamination Certificate

active

06523833

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a low load seal used for sealing of fluid.
2. Description of the Related Art
As a seal attached to a dovetail groove
31
of a trapezoid cross sectional configuration among various conventional seals, an O ring
30
, as shown in
FIGS. 9A through 9C
, is generally used.
A seal
35
(disclosed in Japanese Utility Model provisional publication No. 3-127866) as shown in
FIGS. 10A and 10B
is known.
In the present invention, as shown in
FIGS. 9A through 9C
, the diameter of the O ring
30
is larger than depth of the dovetail groove
31
on a member
32
, and a part of the O ring
30
protrudes from an opening portion of the dovetail groove
31
. As shown in
FIG. 9A
, the O ring
30
does not fall out of the dovetail groove
31
because the diameter of the O ring
30
is larger than width of the opening portion of the dovetail groove
31
. As shown in
FIG. 9A
,
30
a
is a parting line (flash) in forming to which the member
32
and member
33
come relatively close, as shown in FIG.
9
B. The O ring
30
is pressed by a facing surface
34
of the member
33
to be squeezed and given a predetermined squeeze amount (rate), and fluid is sealed inside and outside of the O ring as a border.
As shown in
FIG. 10A
, the seal
35
disclosed in Japanese Utility Model provisional publication No. 3-127866 is formed in a cross-sectional configuration composed of a large arc portion
36
attached to the dovetail groove
31
, and a pair of extruding portions
37
, formed as to branch and extrude from the large arc portion
36
to the opening portion side of the dovetail groove
31
. A sucker portion
39
is formed with the pair of extruding portions
37
and the concave portion
38
. As shown in
FIG. 10B
, the member
32
and the member
33
come close to each other to press the sucker portion
39
onto the facing surface
34
, and the sucker portion
39
adheres to the facing surface
34
by absorption to seal the fluid.
In the O ring
30
, described with reference to
FIG. 9
, a large compression load is required to give the predetermined squeeze amount (which amount is distributed equally between the member
32
, the member
33
, and the O ring
30
), sealing ability is decreased for deformation of mating faces of the members
32
and
33
(or permanent deformation of the O ring
30
), and life of equipment (a semiconductor apparatus, for example) is shortened thereby. Further, the O ring
30
is difficult to attach because the diameter of the O ring
30
is larger than the width of the opening portion of the dovetail groove
31
. The O ring
30
may be twisted in attachment, the parting line
30
a
may become the sealing face (the parting line
30
a
may contact the facing surface
34
of the member
33
), and sealing ability may be spoiled.
In case of a gate valve in which the member
32
is a gate and the member
33
is a valve seat, a large difference is generated in the compression amount of the O ring
30
for dimensional tolerance of each part. Because the valve is composed of many parts, load excessively changes, and the mechanism is overplanned to resist the load. Further, insufficient compression amount in an assembled state may cause leaks, problems of increasing compression permanent deformation and dust, and generation of cracks due to excessive load, which works on the O ring
30
. In the event that, both sides of the gate valve are atmosphere and vacuum or vacuum and vacuum, the position of the gate is changed by flection of the mechanism caused by pressure difference, compression amount of the O ring
30
is changed, and it is difficult to obtain an appropriate sealed state.
In the seal
35
, described with reference to
FIG. 10
, it is necessary to elastically deform the large arc portion
36
significantly; namely, to give large squeeze amount because the sucker portion
39
is strongly pressed to the facing surface
34
by the elasticity of the large arc portion
36
, as in FIG.
10
B. Therefore, there is a problem in that the life of the equipment is shortened by high compression loads. Thus, the seal
35
can be easily damaged due to the strong force of members
32
and
33
, between which extruding portions
37
are sandwiched.
A seal
40
shown in
FIG. 11
(disclosed in Japanese Patent Provisional Publication Number 10-311430), which is fitted into a groove
41
, of which a cross-sectional configuration is a rectangle having a shallow concave portion
42
on a bottom wall face side of the groove
41
, and a half-circular protruding portion
43
on an opening portion side of the groove
41
. The seal
40
, of which the width on the opening portion side is set to be larger than the width of the groove
41
in unattached state, is compressed into the groove
41
to be prevented from falling off. With regard to the seal
40
, pressing deformation of the half-circular protruding portion
43
is released by the concave portion
42
. When the half-circular protruding portion
43
is pressed by the facing surface
34
of the member
33
, a relatively large compression load is required to give the predetermined squeeze amount (rate). This is because the rate of width dimension w
1
of the half-circular protruding portion
43
, when compared to the width dimension w of the groove
41
, is large and the rate of the protruding dimension h
1
of the half-circular protruding portion
43
from the opening portion to depth dimension of the groove
41
is small.
It is therefore an object of the present invention, solving the problems above, to provide a low load seal having excellent attachability to a dovetail groove, prevented from being twisted when attached into the dovetail groove, and extending life of the equipment by demonstration of good sealing ability with low load.


REFERENCES:
patent: 3214182 (1965-10-01), Herbruggen
patent: 3575431 (1971-04-01), Bryant
patent: 4123068 (1978-10-01), Van Gorder
patent: 4921258 (1990-05-01), Fournier et al.
patent: 5180008 (1993-01-01), Aldridge et al.
patent: 5328178 (1994-07-01), Nies
patent: 5445393 (1995-08-01), Ramberg
patent: 5482297 (1996-01-01), Burns et al.
patent: 6129358 (2000-10-01), Kiesel et al.
patent: 6264206 (2001-07-01), Hashizawa et al.
patent: 6273231 (2001-08-01), Koschmieder et al.
patent: 3-127866 (1991-12-01), None
patent: 10-311430 (1998-11-01), None

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