The invention concerns a plain bearing composite material comprising a carrier layer made from steel and a sliding layer which is disposed thereon in such a manner that it cannot be removed, the sliding layer being made from an aluminium bearing alloy.
Plain bearing composite materials of this type are conventionally known and are used, in particular, for producing plain bearing shells for connecting rod bearings and for crankshaft bearings in the crankcase of a combustion engine of a vehicle. The use of such a plain bearing composite material for producing rolled bearing bushings, e.g. connecting rod bearing bushings or piston pin bushings which bear the piston pin in the piston, is also known in the art.
DE 198 00 433 C2 does not describe plain bearing composite materials comprising a carrier layer made from steel, but deals with a continuous casting method for casting an aluminium plain bearing alloy comprising 3 to 6 weight % of zinc, 0.3 to 2.0 weight % of copper, 0.2 to 1.0 weight % of magnesium, 0.3 to 2.0 weight % of silicon and 2 to 4.5 weight % of lead. Finely distributed drop-shaped lead precipitations are thereby formed in the continuous casting piece with the drops having dimensions of less than 10 μm. When this aluminium alloy is used as a plain bearing alloy, the lead acts as finely and homogeneously distributed lubricant.
EP 0 440 275 B1 also relates to casting of monotectic aluminium bearing alloys. This document discusses aluminium bearing alloys for producing plain bearing materials comprising one or more of the components: 1 to 50 weight %, preferably 5 to 30 weight % of lead, 3 to 50 weight %, preferably 5 to 30 weight % of bismuth, and 15 to 50 weight % indium and additionally one or more of the following components: 0.1 to 20 weight % of silicon, 0.1 to 20 weight % of tin, 0.1 to 10 weight % of zinc, 0.1 to 5 weight % of magnesium, 0.1 to 5 weight % of copper, 0.05 to 3 weight % of iron, 0.05 to 3 weight % of manganese, 0.05 to 3 weight % of nickel and 0.001 to 0.30 weight % of titanium. This document does not give any further information about the exact composition of an aluminium alloy.
EP 0 190 691 A1 discloses a plain bearing composite material comprising a carrier layer made from steel and a sliding layer which is disposed thereon in such a manner that it cannot be removed and consists of an aluminium bearing alloy composed substantially of 4 to 9 weight % of bismuth, 1 to 4.5 weight % of silicon, 0 to 1.7 weight % of copper, 0 to 2.5 weight % of lead, the rest being aluminium, in accordance with claim 1 of this document. Claim 3 of this document mentions one or more of the materials selected from the group consisting of nickel, manganese, chromium, tin, antimony and zinc as further additives, wherein the portion of zinc may amount to up to 5 weight %. The compositions of the aluminium bearing alloy precisely disclosed in this document suggest that the combined use of bismuth and lead is advantageous.
A plain bearing composite material comprising a carrier layer of steel and a sliding layer disposed thereon in an irremovable fashion and consisting of AlZn5Pb4Si1.5Cu1Mg has been disclosed under the trade name KS R41.
It is the object of the present invention to provide an environment-friendly plain bearing composite material of the above-mentioned type, comprising an aluminium bearing alloy which is easy to cast and shape and at the same time has excellent tribological properties.
This object is achieved in accordance with the invention by a plain bearing composite material comprising the features of the independent claim.