WO2005038277A1

WO2005038277A1 - Friction bearing for a shaft

Info

Publication number: WO2005038277A1
Application number: PCT/DE2004/001693
Authority: WO
Inventors: Martin Huber
Original assignee: Robert Bosch Gmbh
Priority date: 2003-09-25
Filing date: 2004-07-28
Publication date: 2005-04-28
Also published as: DE10344589A1

Abstract

The invention relates to a friction bearing (1), with at least one bearing point (9), for a shaft (2). According to the invention, the bearing point (9) is connected by means of at least one capillary (15) to at least one lubricant reservoir (14), embodied as a cavity (24) in the bearing body (3), which does not have a capillary effect due to the size thereof.

Description

Plain bearing for a shaft

The invention relates to a plain bearing for a shaft with at least one bearing.

State of the art

Plain bearings for shafts are known. Sintered plain bearings are used in particular for DC motors and for high-speed AC motors, i.e. those made of sintered iron or sintered bronze, the material structure of which, due to the manufacturing process, has a large number of pores and cavities into which a lubricant, such as oil, is incorporated in the course of an impregnation process. is brought, which serves to lubricate the bearing.

A disadvantage of these oil-impregnated sintered bearings is that there is no defined lubricant delivery, but rather the lubricant delivery depends on the surface condition of the bearing point and the shaft, the thoroughness of the lubricant dipping process during manufacture, the concentricity of the shaft within the plain bearing, the temperature of the bearing point and the viscosity of the Lubricant depends. Furthermore, the release of lubricant from the sintered material onto the sliding point depends on the speed of the shaft. Another disadvantage is that the amount of lubricant that is made available to the bearing point depends on the absorption capacity of the sintered material. Another disadvantage is that the lubricating properties are inadequate when the shaft starts to cold, because of the viscosity the one in the sintered material! The lubricant introduced does not guarantee uniform wetting of the bearing point and the shaft at very low temperatures. It is also disadvantageous that the lubricant introduced into the sintered material tends to paste over time, as a result of which an adequate amount of lubricant is no longer provided at the bearing point.

Advantages of the invention

In contrast, the plain bearing according to the invention offers the advantage that at least one lubricant depot designed as a cavity is provided inside the bearing body, which allows the absorption of a larger amount of lubricant, it being provided that due to its size, this lubricant depot does not act capillary with regard to the lubricant introduced , As a result, a sufficiently large amount of lubricant can be made available over a long period of time and under different operating conditions.

In a further development of the invention, it is provided that the slide bearing consists of at least two bearing body parts which touch one another in a sectional plane running through the slide bearing, the surfaces of the bearing body parts facing one another being designed as contact surfaces.

In a preferred development, it is provided that the contact surfaces of the at least two bearing body parts are flat surfaces that face each other and that are perpendicular to the longitudinal axis of the shafts. The bearing can therefore be easily assembled from the two bearing body parts. Of course, it is also possible not to make the contact surfaces flat, but rather to consist of several planes or of a surface that is curved in itself, provided that the contact surfaces of the two bearing body parts are mirror images of each other so that they can be assembled into a bearing body that has no unwanted joints. This is particularly the case when the contours of the two contact surfaces are mirror-symmetrical about a point lying in the shaft axis and the section plane between the two bearing body parts.

In a development of the invention it is provided that at least one capillary and / or the lubricant depot is formed in the area of the contact surfaces. In this way, an easy manufacture of the capillary and / or the lubricant depot is achieved, since the contact surfaces are easily accessible as surfaces of the bearing body part before the assembly of the at least two bearing body parts, and therefore the formation of these elements can be carried out in a simple manner, for example by simple surface machining - such as drilling, grinding, milling or by spark erosion. It is also possible to design these elements in the manufacture of the bearing body parts.

In a particularly preferred development of the invention, it is provided that the lubricant depot is formed by at least one first depression in at least one of the contact surfaces. The lubricant depot is formed by simple surface processing, namely the application of at least one recess by any suitable processing method.

In a further development of the invention, it is provided that the capillary is formed by at least one further, second depression in at least one of the contact surfaces. When the two bearing body parts are assembled, the depression or the depressions become self-contained volumes. However, it is provided that the lubricant depot and the capillary are connected to one another, so that the capillary opens into the lubricant depot. A further development of the invention provides that the capillary is formed between the lubricant depot and the shaft or bearing point, so that between the lubricant depot and the shaft or the bearing point there is a connection which acts capillary with respect to the lubricant and which supplies the lubricant for Deposit allowed.

In a further development of the invention it is provided that the capillary is arranged radially to the shaft axis.

In a further development of the invention, it is provided that a lubricant depot is assigned to each capillary in the case of a plurality of capillaries. This ensures that even if a lubricant depot or a capillary fails, the bearing point is supplied with lubricant from other capillaries and / or other lubricant depots of the same bearing.

According to a development of the invention, it is provided that the capillary leads to the shaft or to a lubricant cavity assigned to the shaft. In this way, it can be achieved that lubricant is supplied to the bearing point over a larger area, so that sufficient wetting of a sufficiently large bearing point area with lubricant is ensured, in particular when the cold starts up or at high speeds.

According to a further development of the invention, it is provided that a lubricant depot is assigned to several capillaries. A rather large-volume lubricant depot therefore interacts with a large number of capillaries, preferably independently of position and in terms of volume.

In a further development of the invention, it is provided that the lubricant depot is designed as a depression which surrounds the shaft in an annular manner in at least one of the bearing body parts. This forms, for example, a circumferential channel or a half torus, the equatorial plane of which is formed by the contact surface. It is precisely in this way that a particularly position-independent supply of lubricant is achieved if the capillaries are arranged radially to the shaft axis and are evenly spaced around them, since a lubricant supply takes place in every position which the plain bearing can assume in space and in particular around the shaft axis.

One embodiment of the invention provides that in addition to the presence of the lubricant reservoir and the capillaries, the bearing body part material itself is impregnated with lubricant.

A preferred embodiment of the invention provides that the bearing body parts have rotary aligning means for their relative position to one another, so that not only easier, precise fitting can take place, but also ensures that, for example, half-formed recess contours form a whole in each bearing body part put together in alignment. For example, fitting lugs and / or fitting types can be provided on the circumference of the bearing body parts, which result in an unmistakable, form-fitting fit. As a result, the bearing body parts can be clearly aligned with one another.

In order to avoid loss or loss of lubricant after filling, it is further provided that the slide bearing material as a whole is soaked with the lubricant. The lubricant depot can also be easily filled by vacuum-soaking the entire plain bearing with the lubricant in a conventional manner. Not only are the pores of the material filled with the lubricant, but also larger cavities within the bearing body, in particular namely the lubricant depot and the capillary. Advantageous embodiments are mentioned in the subclaims.

DRAWINGS The invention is explained in more detail in several exemplary embodiments below with reference to drawings.

Show it:

Figure 1 is a slide bearing consisting of two bearing body parts in longitudinal section through the axis of a shaft;

Figure 2 shows a contact surface of a bearing body part in supervision;

Figure 3 shows another contact surface of another bearing body part in supervision and

Figure 4 shows another contact surface of another bearing body part in supervision.

Description of the embodiments

FIG. 1 shows a plain bearing 1 for a shaft 2, with a bearing body 3 which consists of two bearing body parts, namely the upper bearing body part 4 and the lower bearing body part 5.

The bearing body parts 4 and 5 each have a surface 6 which is opposite to the other bearing body part and which - lying one on top of the other - in the state shown in FIG. 1 forms a contact surface 7 in a sectional plane 8 of the plain bearing 1. The bearing body parts 4, 5 face each other in such a way that they touch areas of the surface and outside edge-tight with the contact surfaces 7. Each bearing body part 4, 5 has at least one bearing point 9. The bearing point 9 is in direct contact with the shaft surface 10 of the shaft 2. The shaft axis 11 of the shaft 2 is also shown.

The following description relates to a left or right side of a bearing body part 4, 5 in FIG. 1 with respect to the shaft axis 11.

Each surface 6 of a bearing body part 4, 5 forming a contact surface 7 has a first depression 12 and a second depression 13. The second depression 13 is connected to the first depression 12. The first depression 12 and the second depression 13 are ring contours around the shaft axis 11. The bearing body parts 4, 5 are opposite to the cutting plane 8 with the contact surfaces 7 in mirror image. As a result, the first depression 12 of the lower bearing body part 5 and the first depression 12 of the upper bearing body part 4 are also mirror images of the sectional plane 8. The same applies to the second recess 13 of the bearing body parts 4, 5.

In the assembled state, as shown in FIG. 1, the first depression 12 of the upper bearing body part 4 forms a cavity 24 with the first depression 12 of the lower bearing body part 5, namely the lubricant reservoir 14. The second depression 13 of the upper bearing body part 4, together with the second depression 13 of the lower bearing body part 5, accordingly forms the capillary 15.

Both the lubricant reservoir 14 and the capillary 15 are accordingly designed as ring contours around the shaft axis 11. The lubricant depot 14 thus has a toroidal or approximately toroidal cross section. The capillary 15 is designed as a very flat ring contour, so the distance from its inner to its outer diameter is considerably greater than its clear height. With its end facing the shaft 2, the capillary 15 opens into a lubricant cavity 16 formed along the shaft 2 up to the bearing point 9, the mouth 17 resulting.

In each end region 18 of each bearing body part 4, 5, an annular tapping 19 is formed, which surrounds the shaft 2 and forms a lubricant volume 20.

The bearing point 9 surrounds the shaft 2 in a ring shape, so that it touches the shaft surface 10 with only slight play.

The bearing body parts 4, 5 also have rotary alignment means 21, which are formed opposite one another either as a fitting nose 22 or as a receptacle 23. In the unmounted state of the two bearing body parts 4, 5, the fitting lug 22 and the receptacle 23 can still be moved freely with respect to one another. The area shown on the left in FIG. 1 shows this state of the rotary alignment means 21 before final assembly. In the final assembled state, as it is shown as a rotating alignment means 21 on the right in FIG. 1, the receptacle 23 is positively connected to the fitting nose 22, which can be done, for example, by a shaping or pressing process. The manner in which the rotary alignment means 21 is designed and whether or in what way a final fixation takes place is not important for the function of the invention. Any suitable rotary alignment tool can be considered. It is also conceivable to provide either a releasable or no fixed connection of the bearing body parts 4, 5 via the rotary alignment means 21. In the latter case, the plain bearing 1 can then be easily dismantled again, for example for revision purposes.

The required concentricity of the bearing body parts 4, 5 with respect to one another can also be produced after the positive connection by means of a calibration process or another suitable method. The slide bearing 1 is completely filled with a lubricant, not shown, for example with an oil, by vacuum soaking.

In this case, all cavities are filled, apart from the pores of the material, in particular also the lubricant reservoir 14, the capillary 15, the lubricant cavity 16 and the lubricant volume 20.

As a result, there is already a lubricant supply at the bearing point 9 as soon as the shaft 2 starts up for the first time. When the shaft is in operation, however, lubricant can be tracked out of the lubricant reservoir 14 via the capillary 15 and the lubricant cavity 16 via the mouth 17. This ensures that even in long-term operation, when the lubricant is reduced by the action of heat or by expulsion from the bearing 9 at the bearing 9, there is always an afterflow, which is a constant film of lubricant between the bearing 9 and the shaft surface 10 ensures that, for example, hot running or excessive noise is avoided.

It is particularly advantageous that the lubricant is fed from the lubricant depot 14 to the bearing point 9 due to the capillary action of the capillary 15 without further action, in particular without external intervention. Lubricant is available via the lubricant cavity 16 over a large area of the shaft surface 10 facing the capillaries 15, so that large-area prewetting already takes place and the lubricant film between the bearing point 9 and the shaft surface 10 is prevented from tearing off.

Lubricant expelled from the bearing point 9 during the operation of the shaft 2 in the direction of the end region 18 of the slide bearing 1 collects in the ring tapping 19 designed as a lubricant volume 20 in the end region 18 of the bearing body part 4, 5 prevents the lubricant from being finally lost through expulsion from the slide bearing 1 along the shaft surface 10 beyond the end region 18 of the slide bearing 1. Sufficient lubrication is also ensured between the end region 18 of the sliding bearing 1 and the shaft surface 10.

It is more important, however, that there is an interaction between the lubricant depot 14 and the capillary 15 assigned to it and the lubricant cavity 16 on the one hand and the lubricant volume 20 on the other hand via the bearing point 9: With changing pressure and temperature conditions inside and outside the plain bearing 1, lubricant becomes once preferably driven from the inside to the outside, ie from the lubricant cavity 16 via the bearing point 9 to the lubricant volume 20, but once inside, ie from the lubricant volume 20 to the lubricant cavity 16 and also back into the lubricant depot 14. This is particularly the case when the warm slide bearing 1 cools, which leads to a reduction in pressure within the cavities 24 arranged in the slide bearing 1, as a result of which the lubricant expelled into the lubricant volume 20 is pushed back inwards by the external pressure, in particular the air pressure, acting from outside. This not only prevents premature loss of lubricant, but also reduces the risk of the lubricant becoming contaminated because the lubricant is kept in constant motion and cannot settle at one point on the plain bearing 1.

FIG. 2 shows a plan view of a lower bearing body part 5 at the level of a contact surface 7 or cutting plane 8.

In this embodiment it is provided that a shaft 2 shown here in cross section is assigned a plurality, namely two lubricant depots 14, each with its own capillary 15 and its own lubricant cavity 16. Both the lubricant depot 14 and the capillary 15 and the lubricant cavity 16 can advantageously by means of a suitable machining process, for example by machining a surface 6 of the bearing body part 5 such as drilling, milling, spark eroding or a combination thereof, or already during the forming process of the bearing body part 5 are formed as a first depression 12 and a second depression 13.

The respective cavity 24 of the lubricant depots 14 and the capillaries 15 is created when the bearing is assembled by placing an upper bearing body part 4 of mirror-image design, which has corresponding first depressions 12 and second depressions 13.

As a further embodiment, provision is made for only one of the two bearing body parts 4, 5 to be provided with depressions 12, 13 and for the respective opposite bearing body part to be provided with a smooth surface 6; In this case, the lubricant depot 14 and the capillary 15 are only formed as half a volume, but the plain bearing 1 is once again simplified and cheaper to produce.

The lubricant, not shown in more detail, is supplied to the shaft surface 10 and the bearing point 9 via the capillary 15 and the lubricant cavity 16.

In this embodiment, the mirror-symmetrical arrangement of the cavities containing lubricant, namely in particular the lubricant deposits 14, the capillaries 15 and the lubricant cavities 16, is advantageous since the shaft surface 10 not only once but twice on the lubricant cavity 16 with each revolution of the shaft 2 the lubricant is wetted. FIG. 3 shows a plan view of a lower bearing body part 5 with a shaft 2, at the level of a contact surface 7 or cutting plane 8.

In this embodiment, it is provided that the lubricant reservoir 14 is designed as a first depression 12 of the surface 6, the first depression 12 being arranged essentially concentrically around the shaft axis 11 in the bearing body part 5, that is to say forming an annular contour with an at least approximately half-toroidal cross section. The capillaries 15 are each arranged as second recesses 13 radially towards the shaft axis 11 towards the lubricant reservoir 14. The capillaries 15 are evenly spaced from one another, so they each enclose the same angle α. Small deviations in the size of the angle α are insignificant for the function of the exemplary embodiment.

This embodiment provides a particularly position-independent and reliable supply of the bearing 9 and the shaft surface 10 with the lubricant, not shown in detail, since the lubricant, not shown in detail, is constant regardless of the position that the plain bearing 1 or the shaft 2 can assume in space reaches the bearing point 9 from the rather large-volume lubricant depot 14 via at least one but usually several capillaries. A reduced inflow from a capillary 15 is easily compensated for by an increased inflow from another capillary 15, since there is a self-contained pressure system between the lubricant reservoir 14, all the capillaries 15 emanating therefrom and the bearing point 9.

The respective cavity 24 of the lubricant depots 14 and the capillaries 15 is created, as before during assembly of the bearing, by placing an upper bearing body part 4 which is embodied as a mirror image and has corresponding first depressions 12 and second depressions 13. As a further embodiment, provision is also made here for only one of the two bearing body parts 4, 5 to be provided with depressions 12, 13 and for the respective opposite bearing body part to be provided with a smooth surface 6; In this case, the lubricant depot 14 and the capillary 15 are only formed as half a volume, but the plain bearing 1 is once again simplified and cheaper to produce.

FIG. 4 shows a lower bearing body part 5 with a shaft 2 as well as lubricant depots 14 and capillaries 15, which are produced as above, and which are not arranged symmetrically and non-uniformly on the surface 6 of the bearing body part 5 or around the shaft 2. Depending on the intended use of the plain bearing 1, an embodiment which is particularly suitable for reliable lubricant supply can be formed by capillaries 15 and lubricant deposits 14 which differ in number and shape. The advantages according to the invention are common to all these embodiments, in particular the large-volume supply of lubricant in the lubricant depot 14, the defined supply of the lubricant to the bearing point 9 and to the shaft surface 10 via the capillaries 12 and the easy manufacture by simple surface treatment of the surfaces 6 of the bearing body parts 4, 5th

Claims

claims

1. plain bearing with a bearing body and at least one bearing point for a shaft, characterized in that the bearing point (9) via at least one capillary (15) with at least one in the bearing body (3), due to its size not acting as a cavity, as a cavity ( 24) trained lubricant depot (14) is connected.

2. plain bearing according to claim 1, characterized in that the bearing body (3) consists of at least two contacting bearing body parts (4, 5).

3. plain bearing according to claim 2, characterized in that the contact surfaces (7) of the bearing body parts (4, 5) facing each other, flat surfaces (6), which are _t perpendicular to the shaft axis (11) of the shaft (2).

4. Plain bearing according to claim 3, characterized in that the capillary (15) and / or the lubricant reservoir (14) is formed in the region of the contact surface (7).

5. Slide bearing according to one of the preceding claims, characterized in that the lubricant reservoir (14) is formed by at least a first recess (12) in at least one of the contact surfaces (7).

6. Plain bearing according to one of the preceding claims, characterized in that the capillary (15) is formed by at least one further, second depression (13) in at least one of the contact surfaces (7).

7. Plain bearing according to one of the preceding claims, characterized in that the capillary (15) is formed between the at least one lubricant reservoir (14) and the shaft (2) or the bearing point (9).

8. plain bearing according to one of the preceding claims, characterized in that the capillary (15) to the shaft axis (11) is arranged radially.

9. plain bearing according to one of the preceding claims, characterized in that each capillary (15) is assigned a lubricant reservoir (14).

10. Plain bearing according to one of the preceding claims, characterized in that the capillary (15) to the shaft (2) or one of the

Lubricant cavity (16) assigned to shaft (2).

1 1. Slide bearing according to one of the preceding claims, characterized in that a lubricant depot (14) is assigned to several capillaries (15).

12. plain bearing according to claim 11, characterized by an annular, the shaft (2) completely or partially enclosing lubricant reservoir (14).

13. Plain bearing according to one of the preceding claims, characterized in that the material of the bearing body (3) is soaked with lubricant.

14. Plain bearing according to one of the preceding claims, characterized in that the bearing body parts (4, 5) have at least one rotary alignment means (21) for their relative position to one another.