Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2000-03-07
2001-12-25
Footland, Lenard A. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C384S484000, C029S898110
Reexamination Certificate
active
06332718
ABSTRACT:
The present invention relates to the field of rolling bearings, for example ball, roller or needle bearings, etc., equipped with at least one sealing member mounted on one of the rings of the bearing, preferably the outer ring.
The bearing is lubricated using grease packed inside the said bearing before the seals are fitted. The sealing members are intended, on the one hand, to hold the lubricant inside the bearing and, on the other hand, to prevent contaminants from entering the bearing. The outer ring of the bearing has two lateral annular grooves, in each of which a sealing member is mounted. The sealing member may be in the form of a seal or a cheek. The seal is made up of a disc-shaped annular metal reinforcement intended to give it sufficient rigidity. Overmoulded onto this reinforcement is an elastic material (rubber, nitrile, etc.) which provides:
a static seal with the ring on which the seal is fixed in the form of an annular bulge projecting radially from the periphery of the reinforcement,
a dynamic seal with the other ring of the bearing, in the form of an annular lip which rubs against the said other ring.
A seal of this kind is force-fitted into the groove, the elastic material thus being prestressed inside the groove and at the same time centring and holding the seal in the groove while also providing a static seal.
The cheek is a simple metal washer fixed by some appropriate means to the outer ring of the bearing. It is possible, for example, to crimp the periphery of the cheek into an annular groove in the outer ring of the bearing.
The static seal is achieved at the region where the cheek is crimped to the outer ring.
The dynamic seal is achieved in this case without friction by the narrow passage formed between the cheek and the other ring of the bearing.
In this case, the metal reinforcement and the cheek are just one and the same part.
While such seals are satisfactory in most cases, there are applications in which the inner ring is stationary and the outer ring rotates at high speed. The grease is thus centrifuged towards the outside and the resulting pressure tends to cause it to seep through the static seal as grease gradually makes it way between the groove in the outer ring and the periphery of the seal or of the cheek. This phenomenon is aggravated when the bearing operates at a high temperature. The grease then becomes more fluid, and this further encourages leaks through the static seal.
What is more, in the case of the use of a seal, gradual ageing of the elastic material causes it to harden. This phenomenon is an additional cause of lubricant leakage at the static seal. The result of these leaks is that the amount of grease present inside the bearing, that is to say radially between the rings and axially between the seals gradually decreases and the bearing experiences premature failure through lack of lubrication.
This type of problem is encountered, for example, in bearings used in motor vehicle combustion engine belt tensioner rollers.
The outer ring of the bearing rotates at high speed because of the small diameter of the roller and the unit as a whole operates in a hot and confined space.
The object of the invention is to overcome this problem.
The object of the invention is to propose a rolling bearing with an extended life and better lubrication.
The rolling bearing device according to the invention is of the type comprising an outer ring provided with an internal raceway formed on its bore, and at least one groove also formed on its bore and adjacent to a radial face, an inner ring provided with an external raceway formed on its cylindrical exterior surface, at least one row of rolling bodies arranged between the two raceways and at least one sealing member secured to one of the rings. The sealing member comprises an annular metal reinforcement. The device comprises a part for connecting between the reinforcement and the ring which supports it, the connecting part being formed by a filler metal which, after melting and cooling, provides attachment and sealing by moulding to the shapes of the said reinforcement and the said ring. The connecting part is placed in the said groove.
Thus, the reinforcement is secured to the ring by moulding to, and interference of, shapes and not only by the adhesion of the weld. In other words, the connecting part acts like a key or wedge between the reinforcement and the ring. The said groove is of the type which is standard in bearings intended to take seals, and this means that no additional cost is involved.
Advantageously, the reinforcement is in contact with the said groove.
The filler metal may be based on tin, silver or a silver and tin alloy.
Advantageously, the connecting part is formed in an annular groove of the said ring.
The sealing member may comprise just a metal cheek which makes a narrow passage with the other ring, or an annular flexible lip capable of coming into rubbing contact with the other ring.
Another object of the present invention is a method for attaching a sealing member to a rolling bearing ring, of the type comprising an outer ring provided with an internal raceway formed on its bore, and at least one groove also formed on its bore and adjacent to a radial face, an inner ring provided with an external raceway formed on its cylindrical exterior surface, at least one row of rolling bodies arranged between the two raceways, and at least one sealing member secured to one of the rings. The sealing member comprises a rigid metal reinforcement and a flexible lip capable of coming into rubbing contact with the other ring. The said method comprises the formation of a connecting part by melting and cooling a filler metal placed between the reinforcement and the ring which supports it.
In one embodiment of the invention, the filler metal is placed on one edge of the reinforcement, the sealing member is placed on the said ring, the filler metal is heated until it melts, the filler metal spreading between the reinforcement and the said ring, then cooling. The filler metal may be arranged in the form of a coating on the periphery of the reinforcement.
In another embodiment of the invention, with the filler metal in the form of a rod, an appropriate length of rod is cut, the rod and then the sealing member are placed on the said ring, the filler metal is heated until it melts, the filler metal spreading between the reinforcement and the said ring, then cooling. The filler metal may also be in the form of a continuous annulus.
The means for heating the filler metal may be a laser beam or an electron beam.
This then yields a seal-attachment method which is economical and suited to mass production while at the same time allowing a reduction in the amount of elastic material used in so far as this elastic material no longer covers the entire reinforcement but simply forms the sealing lip and a part which has sufficient surface area that it can be fixed conveniently, for example by overmoulding, onto the reinforcement.
The method makes it possible to obtain an extremely effective static seal which does not age in time between the reinforcement of the sealing member and the ring which supports it.
REFERENCES:
patent: 3627391 (1971-12-01), Bingle
patent: 4578848 (1986-04-01), Dickson
patent: 4632401 (1986-12-01), Kar et al.
patent: 5862592 (1999-01-01), Harimoto et al.
patent: 2 261 459 (1974-02-01), None
patent: 1342239 (1974-01-01), None
patent: 2000-291786 (2000-10-01), None
patent: WO 98/34053 (1998-08-01), None
Brandenstein Manfred
Tadic Vedran
Van De Sanden Johannes Franciscus
Footland Lenard A.
SKF France
Smith , Gambrell & Russell, LLP
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