Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Reexamination Certificate
2000-09-08
2002-07-02
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C049S336000
Reexamination Certificate
active
06412785
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oil seal for a door closing device that has a longer longevity.
2. Description of the Related Art
Taiwan Utility Model Publication No. 342025, issued on Oct. 1, 1998 and entitled “BASE STRUCTURE FOR A DUAL-FUNCTION DOOR CLOSING DEVICE”, as illustrated in
FIGS. 1 and 2
of the drawings, discloses an automatic door closing device
9
that is mounted to a door. When the door is opened, a shaft
91
is turned, a movable plug
93
, via transmission by a gear
92
on the shaft
91
and a rack (not labeled) that is formed on the movable plug
93
and meshed with the gear
92
, is moved to compress an elastic element
94
and make working fluid to flow. When the force that opens the door vanishes, the door is automatically closed under the action of the return force of the elastic element
94
and back flow of the working fluid. An oil seal
95
is mounted to the shaft
91
to avoid leakage of the working fluid via a gap between the cover
96
and the shaft
91
. Nevertheless, during flow, the working fluid exerts a force on the oil seal
95
and thus makes the oil seat
95
press against a peripheral edge
97
defining a central annular hole of the cover
96
. After a term of usage, the oil seal
95
deforms. Or, an annular recess is generated due to friction between the oil seal
95
and the peripheral edge
97
of the cover
96
. Leakage occurs accordingly, as the oil seal
95
no longer provides the required sealing effect.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a door closing device with an oil seal that is not easy to deform and damage and is thus durable.
A door closing device in accordance with the present invention comprises a main body, a shaft, an annular cover mounted in the main body, and a planar gasket. Two ends of the shaft are rotatably supported in the annular cover by a collar. The planar gasket is mounted around the shaft and between the collar and a peripheral edge defining a central annular hole of the annular cover. The planar gasket includes an inner diameter approximately the same as an outer diameter of the shaft and an outer diameter approximately the same as an inner diameter of the annular cover. The planar gasket further includes two opposed planar surfaces.
The planar gasket is made from an oil-resisting material, such as tetrafluoro-ethane resin.
Other objects, specific advantages, and novel features of the invention will become more apparent from the following detailed description and preferable embodiments when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4220051 (1980-09-01), Catlett
patent: 4293291 (1981-10-01), Link
patent: 4333270 (1982-06-01), Catlett
patent: 4998932 (1991-03-01), Rosen et al.
patent: 5036620 (1991-08-01), Beran et al.
patent: 5586724 (1996-12-01), Allen
patent: 342025 (1998-10-01), None
Bacon & Thomas PLLC
Beres John L.
Knight Anthony
Taiwan Fu Hsing Industrial Co., Ltd.
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