DE9300397U1 - bearings - Google Patents

Description

Description:

The invention relates to plain bearings which are manufactured using plastic materials.

Plain bearings of this type are made of nylon, Teflon and other suitable materials, to which fillers such as graphite or molybdenum disulfide are sometimes added in order to improve the sliding properties of the bearing.

A very common problem with plain bearings made of plastic materials is that they can only be used within a relatively small temperature range, since the thermal expansion coefficients of plastic materials are usually much higher than those of metallic or ceramic materials.

Although plain bearings generate significantly less running noise than roller or ball bearings, it is a constant problem to provide plain bearings with the lowest possible running noise.

It is the object of the invention to provide a plain bearing which is characterized by good noise behavior and can serve as a cost-effective replacement, in particular for metallic sintered bearings. It is a further object of the invention to provide such a plain bearing for use in an electric motor or in a motor vehicle.

These objects are solved by the specification of claim 1.

Further embodiments of the invention emerge from the subclaims and the drawing.

It shows:

Fig. 1 shows a cross section through a first plain bearing according to the invention.

A rotatable shaft 11 is located both within a porous plastic molded body 14 and in the central area of a bearing ring 13 or a bearing ring 15. The shaft 11 is preferably made of a metallic or ceramic material. (In the sense of the so-called kinematic reversal familiar to the expert, the shaft can also be designed as a fixed axis). To reduce the bearing friction between the plastic molded body 14 and the shaft 11, the latter preferably has a proportion of solid lubricant such as graphite on the common contact surface. The solid lubricant can also be homogeneously mixed into the plastic material of the molded body. In addition, the molded body serves as a reservoir for an essentially liquid lubricant such as grease or oil. It is suitable for this due to its porous structure. This structure can be advantageously produced by a sintering process of powdered plastic starting materials in a suitable form. A particularly suitable material is the polyethylene material ¹¹ GUR" from Hoechst.

Although the molded body 14 partially takes on the functions of a plain bearing, its main function is the storage of a liquid lubricant, which is required at the precisely dimensioned bearing points 16 and 17.

These only have the thermal expansion coefficient of the intended bearing rings 13 or 17, which are made of metal or ceramic, for example, preferably steel. The bearing rings are preferably sintered onto the molded body 14 during the sintering process, so that a mechanically resilient connecting surface is created between the two materials.

When the bearing is in operation, the shaft 11 is constantly wetted with liquid lubricant (not shown), which reaches the lubrication gaps (16 and 17) of the bearing rings 13 and 15 in particular. Depending on the speed of the shaft and the surface tension of the liquid lubricant, this flows outwards in a radial direction via the bearing ring 13 or 15. In a special embodiment of the invention, this is taken into account in that a protruding edge or, more generally, a projection takes up radially flowing lubricant and in this way feeds it into a circuit.

Fig. 2 shows a further embodiment of the invention. There is also a molded body 14 made of essentially porous plastic material, which either encloses a hollow cylindrical bearing ring 13 or is inserted into a drilled, egg-shaped bearing ring 21, preferably by a sintering process. The latter bearing ring has the advantage that a precise, temperature-stable outer diameter is specified over a more or less large part of the bearing, while at the same time a re-greasable sliding surface 23 is specified for a snap ring or a locking washer 22. In this way,

ensures the lubrication of the bearing acting in the axial direction.

A further embodiment of the invention is shown in Fig. 3.

which also shows the cross-section of a bearing.

Bearing ring 31 acts like a combination of bearing rings 13 and 15. It defines a lubrication gap or running surface 34.

Bearing ring 32 can be manufactured relatively inexpensively by a pressing or stamping process, provided it is made of metal. It defines a lubrication gap 3 3.

Another cross-section through a similar bearing according to the invention is shown in Fig. 4.

Bearing ring 41 defines a lubrication gap 42 for radial loading of the bearing. At the same time, a lubrication gap is defined for axial loading of the bearing. The axial load is transferred to the molded body 14 via shaft 11 and locking washer 43. Radially flowing lubricant is collected in the notch 45 and fed to a lubricant circuit.

A further embodiment of a bearing according to the invention is shown in Fig. 5, which also shows a cross section. The essentially porous molded body 14 is sintered or glued to the end piece 51, which supports the shaft 11 both axially and radially. The individual design of an end 52 of the end piece 51 results in a variety of possibilities for designing the connecting surface between the molded body 14 and the end piece to be sufficiently large.

Greasing of the shaft II occurs along the lubrication gap 53. Capillary forces also transport the lubricant to surface areas of the shaft that are not directly in contact with the lubrication gap 53.

Fig. 6 shows another bearing arrangement according to the invention. A bearing bolt 68 is embedded in a fixed base 67. It is surrounded by a molded body made of porous plastic material 62. This supplies lubrication gaps 63, 64, 65 and 66 with lubricant. This bearing is suitable for shafts (alternatively axles) with a comparatively large diameter.

Claims (1)

bearings Expectations: Plain bearings for rotary or linear movement with at least one fixed and at least one movable bearing part, characterized by the following features: there are surfaces for sliding movements which consist of metal or a compact plastic material or a ceramic material, there is a lubricant supply which is embedded in a molded body (14, 62) made of porous plastic material, the molded body being arranged relative to the surfaces for sliding movements in such a way that a continuous wetting of the surfaces with lubricant from the lubricant supply takes place. Plain bearing according to claim 1, characterized in that the shaped body (14, 62) and the surface are arranged so close to one another that both have at least one common contact line or a common contact surface. Plain bearing according to claim 1 or 2, characterized in that the molded body consists essentially of a high or ultra-high molecular weight polyethylene material. Plain bearing according to claim 3, characterized in that the polyethylene material is produced as a sintered material to which a solid lubricant content of 0 to about 30 vol.% is added. Plain bearing according to one of the preceding claims, characterized in that a surface for sliding movements is formed by an inner cylindrical surface of a substantially hollow cylinder-like body. Plain bearing according to one of the preceding claims, characterized in that a surface for sliding movements is formed by a substantially circular end face of a cylinder. Plain bearing according to one of the preceding claims, characterized in that a surface for sliding movements is formed by an external cylindrical surface of a substantially cylinder-like body · · I Plain bearing according to one of the preceding claims, characterized in that a surface for sliding movements is defined by a molded part which is embedded in the molded body made of porous plastic material Plain bearing according to claim 8, characterized in that the molded part has surface portions which, on the one hand, represent a bearing for radial loads and, on the other hand, a bearing for axially directed loads of the bearing. Plain bearing according to one of the preceding claims, characterized in that the molded body made of porous plastic material has a protruding region or projection which serves to absorb lubricant flowing away in the radial direction so that a lubricant circuit is created. Plain bearing according to one of the preceding claims, characterized in that the surfaces for sliding movements are essentially formed by a metallic material or by a liquid crystal polyester material or by a ceramic material. Internal combustion engine with associated transmission, characterized in that the engine or transmission has a plain bearing according to claim 4. Electric motor, characterized in that one or more plain bearings according to claim 4 are present for supporting its shaft. Plain bearing according to claim 4 for use in an engine, in particular an internal combustion engine or an electric motor.