Bearings – Rotary bearing – Plain bearing
Patent
1995-06-28
1998-01-13
Footland, Lenard A.
Bearings
Rotary bearing
Plain bearing
384276, 384294, F16C 3306
Patent
active
057071551
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a multilayer sliding bearing, which is mainly used in internal combustion engines. More specifically, the present invention relates to a bearing having properties of load capacity and wear resistance.
BACKGROUND OF THE INVENTION
The conventional multilayer sliding bearings are made up of a backing layer, usually of steel, an intermediate layer, which is attached onto the backing layer and which is generally made of copper-based alloy, and a sliding layer, which is disposed on the intermediate layer and which is generally obtained from a copper-tin-lead alloy. In some constructions, between the intermediate layer and the sliding layer, there is disposed a barrier, usually of copper or nickel, in order to avoid the diffusion of tin from the sliding layer to the intermediate layer. Between the intermediate layer and the sliding layer there can also exist a bonding layer.
In this prior art bearings, the shaft is supported only on the sliding layer, which is thus subjected to a substantial wear, thereby reducing its embeddability of foreign particles that may penetrate into the bearing during the operation thereof and reducing the useful life of said bearing. Thus, these known bearings present during a first initial phase of their service life good embeddability properties, but a limited load capacity, due to the fact that the efforts to which the shaft is submitted are transmitted integrally and exclusively to the sliding layer made of a softer material. In a second phase of their service life, these prior art bearings present their sliding layers extremely worn out, as no elements were provided to resist to such wear, besides presenting less embeddability caused by the reduction of their thickness. The wear of the sliding layer when the shaft is submitted to high loads, as it occurs in certain high stroke engines, is substantially accelerated, thereby abbreviating the service life of said bearings.
In order to solve these problems, it has been provided solutions where the sliding layers of the bearings present strips of harder material at the radially internal face of the sliding layer of said bearings, said strips being spaced one from the other by grooves filled with softer material, so as to alternate strips or regions of harder material and softer material on said sliding layer, with the aim of improving the properties of resistance to wear and fatigue. In these solutions, the bearing is provided with grooves having a uniform depth and presenting an equal spacing one from the other provided by identical strips of the same harder material at the radially internal face of the sliding layer and that define contact areas with the shaft. This construction of the bearing allows an even distribution of harder material and softer material on said bearing radially internal face that supports the shaft, resulting in uniform properties to the bearing, regardless of particular requirements of every region of said bearing.
A solution for this problem is described in the U.S. Pat. No. 5,000,586 of the same applicant, where the regions alternating harder material and softer material are presented aligned according to a predetermined angle relative the bearing edges, the softer material regions being disposed according to a variable spacing and/or depth, in order to provide a certain preferred distribution of alternated regions with materials of different hardness on the bearing, thus making the latter a bearing presenting variable properties according to a particular load requirement to which said bearing will be submitted.
Nevertheless, it has been observed that, even in this solution that solves the above mentioned problems, the shaft is still subjected to a substantial wear due to friction, caused by the long time of frictional contact between each point of a circumferential alignment of the lateral surface of the shaft portion that is supported on the bearing during each rotation of said shaft, with some regions of the bearing presenting a certain circumfer
REFERENCES:
patent: 1637317 (1927-07-01), Shoemaker
patent: 2187755 (1940-01-01), Ryder
patent: 2648580 (1953-08-01), Lignian
Banfield Robert Richard
Carubelli Ademir
Simao JoseRoberto
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