Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Reexamination Certificate
1999-10-18
2002-11-05
Sandy, Robert J. (Department: 3677)
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
C277S361000, C277S375000, C277S399000
Reexamination Certificate
active
06474652
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a shaft seal device, and more particularly to a shaft seal device for use in a bearing unit such as a plummer block used in iron and steel equipment and the like.
2. Prior Art
A conventional shaft seal device of a bearing unit used in iron and steel equipment and the like, such as an oil seal, requires applying lubricant to sliding parts (lips) thereof. To this end, in steel works, usually an operation of supplying lubricant to lips of oil seals is periodically carried out, which costs time and labor. Further, the conventional shaft seal device has a problem that excess lubricant leaking from lips of oil seals splashes with rotation of the rotary shaft to contaminate or stain its environment, rolled plates produced, etc. To solve this problem, a shaft seal device as shown in
FIG. 13
has been proposed by Japanese Laid-Open Utility Model Publication (Kokai) No. 6-32837.
The proposed shaft seal device
101
is comprised of a pair of core metal members
102
and
103
with fitting collars
109
and
110
integrally fitted one upon another, and seal members
104
and
105
mounted on inner peripheral edges of main bodies
107
and
108
of the core metal members
102
,
103
. The seal members
104
,
105
have flexible lips which are suitably deflected and urged against an outer peripheral surface of a rotary shaft
111
to be sealed, in operation. A clip
115
is fitted on an outer peripheral surface of the lip of the seal member
105
so as to obtain a sufficient urging force of the lip. A lubricant-bearing polymer which is so-called “plastic grease”
106
″ is filled in a gap between the opposed main bodies
107
,
108
of the core metal members
102
,
103
.
Lubricant continuously exudes or oozes from the lubricant-bearing polymer contained in the oil seal is led to the lips of the seal members
104
,
105
to lubricate the same. This can dispense with the periodical operation of supplying lubricant to the lips. Besides, the amount of lubricant exuding from the polymer is so small as to solve the above-mentioned problem of environmental contamination.
According to the conventional arrangement, however, since the exudation amount of lubricant is very small, a sufficient amount of lubricant cannot reach the lips of the seal members
104
,
105
. Further, even if the exudation amount of lubricant is sufficient, the lubricant flows along the inner peripheral portion of the lubricant-bearing polymer and stays at the lowermost inner peripheral portion of the polymer but does not reach the lips.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a shaft seal device which is capable of sealing a rotary shaft in a positive and reliable manner without requiring a periodical lubricant-supplying operation, and is free from contamination of its environment, products, etc. by splashing of excess lubricant leaking from the oil seal lip.
To attain the above object, the present invention provides a shaft seal device for a bearing unit having a bearing fitted on a rotary shaft, and a housing accommodating the rotary shaft extending therethrough, the housing having opposite ends, comprising:
an annular sealing channel formed in at least one of the opposite ends of the housing, the annular sealing channel having opposite lateral wall surfaces; and
an annular lubricant-bearing polymer member accommodated in the annular sealing channel and fitted on the rotary shaft, the polymer member having opposite end surfaces, and an outer peripheral portion;
wherein the polymer member has an inside diameter substantially equal to an outer diameter of the rotary shaft at an initial stage of rotation of the rotary shaft; and
wherein at least part of the opposite end surfaces or the outer peripheral portion of the polymer member is disposed substantially in contact with the opposite lateral wall surfaces of the annular sealing channel.
With the above arrangement, at an initial stage of rotation of the rotary shaft, the inside diameter of the annular lubricant-bearing polymer member is substantially equal to the outer diameter of the rotary shaft so that the polymer member closely contacts the rotary shaft at its inner peripheral surface or is rotated by the rotating rotary shaft while sliding thereon, while at the same time at least part of the opposite end surfaces or the outer peripheral portion of the polymer member substantially contacts the opposite lateral wall surfaces of the sealing channel. As a result, the surfaces of the polymer member in contact with its counterpart function as sealing surfaces to prevent dust and splashed water droplets from entering the bearing unit from the outside of the housing.
The lubricant-bearing polymer member has a function of exuding lubricant from its surfaces and has a nature that its inside diameter and outside diameter become reduced depending upon the exudation amount of lubricant. Therefore, when the inside diameter of the polymer member which initially closely contacts the rotary shaft or slides thereon becomes smaller than the outside diameter of the rotary shaft with exudation of the lubricant from the polymer member as the rotation of the rotary shaft continues, the polymer member becomes tightly fitted on the rotary shaft, whereby the former rotates together with the latter. Thereafter, the rotation of the polymer member is maintained with at least part of the opposite end surfaces or the outer peripheral portion of the polymer member in sliding contact with the opposite lateral wall surfaces of the sealing channel, or the polymer member rotates with delay relative to the rotation of the rotary shaft due to the sliding resistance of the sliding surfaces between the polymer member and the sealing channel. As a result, the surfaces of the polymer member in contact with its counterpart function as sealing surfaces to prevent dust and splashed water droplets from entering the bearing unit from the outside of the housing, as is the case with the initial stage of rotation of the rotary shaft.
In other words, the shaft seal device assumes an initial state in which the inside diameter of the lubricant-bearing polymer member is substantially equal to the outside diameter of the rotary shaft, and a state in which the inside diameter of the polymer member is smaller than the outside diameter of the rotary shaft such that the polymer member is tightly fitted on the rotary shaft. Between the two states, however, no change occurs in the position of the sealing surfaces, though the state of the sealing surfaces changes, and in the both states, it is possible to dust and splashed water droplets from entering the bearing unit.
Further, since the lubricant continuously exudes from the sliding surfaces of the lubricant-bearing polymer member to well lubricate the sliding surfaces, which prevents wear of the polymer member due to the friction between the polymer member and its counterpart as well as formation of a gap between the two members, whereby dust and splashed water droplets can be prevented from entering the bearing unit. The lubricant can exude from the polymer member over a long time, making it unnecessary to periodically supply lubricant. Besides, the exudation amount of lubricant is very small but equal to the minimum amount required for lubrication such that the exuded lubricant will not be splashed with rotation of the rotary shaft, and therefore the environment and the products cannot be contaminated by the lubricant.
Preferably, the shaft seal device according to the present invention includes an annular covering member formed of an elastic material with an inner peripheral channel formed therein. The annular covering member is fitted in the annular sealing channel in an elastically compressed fashion, and the lubricant-bearing polymer member is accommodated in the inner peripheral channel of the covering member. With this arrangement, the lubricant-bearing polymer member will not directly slide on the associated end portion of the hous
Hosoya Masachi
Konishi Kazuaki
Yabe Toshikazu
Frishauf Holtz Goodman & Chick P.C.
NSK Ltd.
Rodgers Matthew E.
Sandy Robert J.
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