FI74786C - Sliding bearing. - Google Patents

Description

74786

SLIDING BEARING - GLIDLAGER

The invention relates to a multilayer plain bearing according to the preamble of claim 1.

The stresses on connecting rods and crankshaft bearings are very high in large piston internal combustion engines, especially diesel engines with high maximum pressures in the cylinders. The main bearing Reina of modern motors is mostly layered bearings. Thus, the aim is to take advantage of the good surface properties of some bearing metals and to avoid their mechanically weak properties by using them as relatively thin surface layers. The so-called trimetallic bearings have a high-load-bearing bearing metal with good thermal conductivity, either lead bronze or light metal, on top of the steel support strip of the bearing. At the top is a thin sliding layer of white metal with a galvanically obtained thickness of between 0.02 and 0.06 mm in the most loaded bearings. In addition, there may be thin anti-diffusion or bonding metal layers between the three material layers. Such bearings have good fatigue strength and thermal conductivity, but they have little chance of adapting to small installation errors or dirt particles penetrating inside the bearing metal.

In prior art plain bearings, the uppermost sliding layer consists of a single layer of alloy or synthetic material. The sliding layer must then be thin, mainly for strength reasons. This has a number of disadvantages, in particular the susceptibility of such a solution to damage during use. When the clearance between the plain bearing and the shaft is small, there is very little play when the bearing heats up, which can cause the bearing to cut. Such a situation may arise when abnormal lubrication of the bearing occurs, for example, so that dirt particles that are not buried 2,74786 break the bearing oil film. The sliding layer consists of a softer material with a lower melting point, so that the greater thickness of the layer as the bearing heats up also provides an advantage in view of a possible clogging situation. On the other hand, it is not possible to implement a thicker sliding layer with the prior art, because the resistance of the surface pressure with respect to fatigue then deteriorates decisively.

The object of the invention is to provide an operationally reliable layered internal and crankshaft bearing for internal combustion engines which has an even better adaptability and burial ability without, however, impairing the load-bearing capacity of the bearing. It is a further object to provide a sliding bearing which allows the use of thicker sliding layers in the bearings, in particular so that a sliding layer component with a low melting point and hardness can be added.

The object of the invention is achieved by a solution according to claim 1. The sliding layer of the plain bearing consists of two or more metal or alloy layers. Thus, the thickness of the sliding layer can be increased without impairing the load-bearing capacity of the bearing, i.e. the ability to withstand the surface pressure. At the same time, the adaptability and burial ability of the sliding layer are advantageously improved, so that the reliability of the bearings is significantly increased. In the preferred solution, two metal or metal alloys with different hardness and melting temperature are used, the material layers formed in which are alternately superimposed on the bearing sliding layer. In such a structure, the harder material layer with its high yield point gives the bearing sliding layer surface pressure resistance properties, while the softer material layers give the sliding layer a favorable thickness.

Alternatively, the different layers of material may consist of metals or alloys of equivalent hardness,

II

3 74786 if the interaction based on different crystal structures of different material layers synergistically provides higher strength. Also, not all the different material layers of the sliding layer need to be completely comprehensive, but different reticulated or lattice-like intermediate layers are also conceivable.

In the preparation of the sliding layer, it is preferable to use a physical gas phase coating method. Such known methods, which as such are not included in the scope of the invention, are e.g. the sputter coating method included in patent publication FI 63600 and various ion coating methods. The desired structure of the sliding layer is obtained by alternately evaporating a different metal or alloy. Other coating methods can also be used to make the sliding layer, e.g. chemical gas phase reaction methods or metal spraying. However, these methods make it more difficult to achieve the sliding layer properties of the invention. For example, in metal spraying, the thicknesses of the different layers of material often become too large, with the additional disadvantage of a porous surface.

The total thickness of the sliding layer should be at least 0.03 mm, preferably at least 0.05 mm, i.e. the thickness of the bearing layer can be increased at least three times compared to known methods without compromising the strength requirements.

The invention will now be described in more detail with reference to the accompanying drawing, in which - Figure 1 shows a perspective view of an embodiment of the invention, and Figure 2 shows the plain bearing according to Figure 1 in section in plane II-II.

In the drawing, reference 1 means a steel shell part or a support strip of a plain bearing. On top of this, an intermediate layer 2 of tin-4,74786 or lead-dominated white metal or bronze is arranged, which is resistant to high loads and has good thermal conductivity. A diffusion barrier layer 3 consisting of e.g. nickel is arranged between the intermediate layer 2 and the actual sliding layer 4.

The actual sliding layer 4 according to the invention is multilayer, and consists of two different metal or metal alloys A and B. Material layers A consist of metals with low hardness and low melting point, e.g. tin-antimony, while material layers B, e.g. aluminum-tin, have a higher content. hardness. By superimposing the material layers A and B on top of each other, the total thickness of the sliding layer can be expanded and the amount of the softer metal alloy A can be considerably increased without compromising the bearing properties of the bearing.

. ··. The various material layers of the sliding layer are formed by a known gas-phase coating method in which, e.g., the desired result is obtained by alternately changing the evaporating substance or source.

The sliding layer is coated with a thin corrosion protection 5, which preferably consists of lead or tin. Such a protective layer also facilitates the running-in of the bearing. The protective layer wears off the sliding surface in a very short period of use.

The invention is not limited to the embodiment shown, but several variations are conceivable within the scope of the appended claims. The number and mutual thickness of the layers of material included in the sliding layer may vary, and it is also possible within the scope of the invention to use more than two different layers of metal or alloy.

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Claims (6)

5,74786 1. A plain bearing for a reciprocating internal combustion engine, in particular a frame or crankshaft bearing for a large diesel engine, which has a so-called three-metal bearing consisting of a steel support strip (1), a light metal or similar intermediate layer (2) and an uppermost sliding layer (4), characterized in that the bearing sliding layer (4) is multilayer consisting of two or more different metal or metal layers A, alternately superimposed ), of which at least two of the metals or alloys have different hardness and melting temperature properties or crystal structure. Plain bearing according to Claim 1, characterized in that the softer material layers (A) are an tin-anti-multi-alloy and the harder material layers (B) are an aluminum-tin alloy. Sliding bearing according to Claim 1 or 2, characterized in that a diffusion barrier layer (3) consisting of nickel is preferably provided between the intermediate layer (2) and the sliding layer (4). Sliding bearing according to one of the preceding claims, characterized in that the sliding layer (4) is coated with a very thin drive-in and anti-corrosion layer (5). Sliding bearing according to one of the preceding claims, characterized in that a physical gas phase coating method, preferably a sputtering or ion coating method, is used to provide said sliding layer (4). Sliding bearing according to one of the preceding claims, characterized in that said sliding layer (4) of the bearing has a total thickness of at least 0.03 mm, preferably at least 0.05 mm. 6 74786