Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Reexamination Certificate
1999-05-19
2001-04-17
Melius, Terry Lee (Department: 3628)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C277S500000
Reexamination Certificate
active
06217031
ABSTRACT:
The present invention relates to a sealing arrangement for a rolling bearing exhibiting at least one row of rolling elements between a first ring and a second ring which are concentric and radially separated from one another by an annular space, at least on one side of the row of rolling elements.
According to an arrangement of this type known from document DE-A-3435437, an elastic seal is fixed, on one side of the row of rolling elements, to the inner ring of the bearing, which ring is extended on this side axially beyond the outer ring. The seal is fixed by a heel engaged in a groove formed in the outer surface of the inner ring, beyond the annular space between the two rings. This known seal comprises two lips of which the first, lying in the annular space between the two rings, presses against the cylindrical inner surface of the outer ring and of which the second, lying outside the bearing, presses against the radial front surface of the outer ring. The first lip is formed at the free end of a substantially axial part of the seal which extends from the zone of attachment of the seal towards the inside of the bearing towards the row of rolling elements, pressing against the cylindrical outer surface of the inner ring, the lip itself being orientated outwards, that is to say making an angle of more than 90° with the said axial part. In this known seal, the second lip which lies outside the bearing has the function of preventing the ingress of dust, moisture and other foreign bodies into the bearing, and the first lip lying inside the rolling bearing supplements the action of the outer lip, that is to say improves the protection against the ingress of moisture and other foreign bodies into the bearing from the outside.
It is emphasized in this document that when the bearing is being lubricated, the first lip of the seal lying inside the rolling bearing allows, on account of its shape, grease to pass from inside the bearing into the space that lies between the two lips so that this space becomes filled with grease, with a view to improving the sealing effect.
Now, in the case of rolling bearings in general, but more specifically in the case of large sized rolling bearings, each time the bearing is lubricated, there is an increase in the pressure inside the bearing, under the effect of which there is a risk that the surplus grease will be ejected from the bearing at the location of the seal. In the case of large-sized rolling bearings, relief valves are provided to allow this surplus grease to be ejected. Nonetheless, the surplus grease does sometimes escape from the bearing via the seals rather than through these valves.
Now, there are numerous applications in which an escape of grease through the bearing seals must be reliably avoided, both during the lubricating of the bearings, therefore while the interior of the bearings is being pressurized, and during normal running of the bearings, during which the rings may effect relative movements, in addition to the rotational movements, under the action of the loads on the bearing.
The present invention envisages a sealing arrangement which prevents grease from escaping from the seal of a bearing, even under the effect of a raised pressure inside the bearing.
The invention furthermore envisages an arrangement which also presents the ingress of moisture, dust and other bodies into the bearing.
The sealing arrangement that is the subject of the invention is intended for a rolling bearing exhibiting at least one row of rolling bodies between a first ring and a second ring which are concentric and radially separated from one another by an annular space, at least on one side of the row of rolling elements. This arrangement comprises, on the said side of the bearing, a single elastic seal fixed to the first ring and exhibiting a first lip pressing against a bearing surface situated on the second ring inside the said annular space. The said first bearing surface exhibits the overall shape of a cone frustum orientated in such a way that its extension towards the aforementioned side of the bearing approaches the said first ring. The first lip of the seal is shaped in such a way that the force with which it presses against the said first bearing surface increases if the pressure inside the bearing increases.
In the sealing arrangement according to the invention, the said first lip, because of its particular shape and the way in which it cooperates with a specially shaped bearing surface, opposes effectively any escape of grease, not only during normal running of the bearing, but also during lubrication, that is to say when the inner space of the bearing is pressurized, and in the case of relative movements that the two rings may effect in addition to the rotational movements, under the action of the loads to which the bearing is subjected during running.
As a preference, the seal may be fixed in a way known per se to the first ring outside the annular space between the two rings and may exhibit, between its zone of attachment and the said first lip, a substantially axial part pressing against a substantially cylindrical surface of the first ring. The said first lip may therefore lie in the extension of the said axial part of the seal, making, with the said axial part, an angle of 90° at the most, preferably an angle smaller than 90°.
However, as a preference, the said axial part of the seal may exhibit a (radial) thickness which increases from the zone of attachment towards the row of rolling elements, and the maximum-thickness free end part of which directly constitutes the said first lip. The first lip is thus directly incorporated into the axial part, the two parts forming a unitary and preferably solid assembly.
In this case, the said axial part of the seal advantageously exhibits, on the side facing towards the second ring, a flank which, at least in line with the said first bearing surface makes, with the axis of the bearing, an angle of inclination that is greater than the angle of inclination of the first generally frustoconical bearing surface.
According to a preferred embodiment, the said flank of the axial part of the seal exhibits a curved profile of which the angle of inclination, with respect to the axis of the bearing, increases from the zone of attachment of the seal towards the free end of the said part, constituting the first lip.
The first bearing surface advantageously makes an angle of between about 30 and 60° and preferably an angle of the order of about 45° with the axis of the bearing.
To protect the bearing against the ingress of moisture, dust or other foreign bodies from the outside, the seal may, in a way known per se, exhibit a second lip which, lying outside the bearing, is pressed against a second substantially radial bearing surface of the second ring of the bearing. The two lips of the seal are therefore preferably dimensioned and shaped in such a way that their lines of pressing against the second ring lie on a frustoconical surface which makes, with the axis of the bearing, an angle of about 30 to 60°, preferably an angle of the order of about 45°. The two lips which act in opposite directions against their bearing surfaces lying on the same ring of the bearing, are thus able in an optimal manner to follow the relative movements that the two rings of the bearing may effect under the effect of the loads (axial, radial, tipping moments) to which the bearing may be subjected during running, without the seal losing its sealing functions.
To make the seal easier to install on the bearing, and improve its retention on the bearing, the seal may advantageously comprise, beyond its zone of attachment, that is to say, with respect to this zone, on the opposite side to the axial part bearing the first lip, an annular heel pressing against the first ring.
REFERENCES:
patent: 2276225 (1942-03-01), Carter
patent: 3203740 (1965-08-01), Peickii et al.
patent: 3245735 (1966-04-01), Dusseldorf
patent: 3594050 (1971-07-01), Guthberg
patent: 4605318 (1986-08-01), Kaiser
patent: 4991982 (1991-02-01), Colanzi et al.
patent:
Bourchois-Jacqurt Pierre
Catalano Denis
Jorrot Franqois-Xavier
Conley Fredrick
Melius Terry Lee
RKS S.A.
Smith , Gambrell & Russell, LLP
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