PLANETARY ROLLER BEARING

Abstract

A Planetary roller bearing having an outer ring with a tooth profile formed on the inner circumference by grooves, an inner ring with a tooth profile formed on the outer circumference by grooves, and a plurality of planetary rolling elements which are accommodated on the end side in cage disks and have a tooth profile formed by grooves. The tooth profiles of the planetary rolling elements engage in the tooth profiles of the rings, wherein a height, viewed axially, of at least one first tooth of the planetary rolling elements or of the outer or inner ring is less than that of the following second tooth, or that an axial distance (d1), viewed axially, of at least one first tooth to the following second tooth less than a distance of the second tooth to the third tooth.

Claims

1. A planetary roller bearing comprising an outer ring with a tooth profile defining teeth formed on an inner circumference by first grooves, an inner ring with a tooth profile defining teeth formed on an outer circumference by second grooves, and multiple planetary rolling elements with a tooth profile defining teeth formed by third grooves, wherein the tooth profiles of the planetary rolling elements engage in the tooth profiles of the inner and outer rings, a height of at least one first tooth, viewed axially, of the planetary rolling elements or of the outer or inner ring is less than a height of a following second one of the teeth and a height of a last one of the teeth, viewed axially, is less than that of a following next-to-last one of the teeth.

2. The planetary roller bearing according to claim 1, wherein a height of more than two of the teeth arranged one behind the other in an axial direction increases from both sides toward a middle.

3. (canceled)

4. The planetary roller bearing according to claim 1, wherein a distance (d1-d7) between several successive ones of the teeth becomes steadily larger.

5. The planetary roller bearing according to claim 4, wherein the distance (d1-d7) between adjacent ones of the teeth increases continuously up to the last one of the teeth.

6. The planetary roller bearing according to claim 4, wherein the distance between adjacent ones of the teeth remains constant after multiple increases.

7. The planetary roller bearing according to claim 1, wherein the planetary roller elements are held on an end side in cage disks.

8. The planetary roller bearing according to claim 2, wherein the middle teeth have diameters that are a same size.

9. The planetary roller bearing according to claim 1, wherein an axial distance (d1) of the at least one first tooth, viewed axially, to the following second one of the teeth is less than a distance of the second one of the teeth to a third one of the teeth.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] An embodiment of the invention is shown in the drawing and is described in more detail below. Shown are:

[0018] FIG. 1 a basic diagram of a planetary roller bearing in a sectioned part view,

[0019] FIG. 2 a basic diagram of a planetary rolling element profiled according to the invention of a first embodiment,

[0020] FIG. 3 a basic diagram of a planetary rolling element profiled according to the invention of a second embodiment,

[0021] FIG. 4 a basic diagram of a planetary rolling element profiled according to the invention of a third embodiment, and

[0022] FIG. 5 a basic diagram of an outer and inner ring with a profiling according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] FIG. 1 shows, in the form of a basic diagram, a planetary roller bearing 1 according to the invention, comprising an outer ring 2, an inner ring 3, and planetary rolling elements 4 that are arranged between these rings and of which only one is shown in this view. Typically, there are multiple, for example, six, eight, or more such planetary rolling elements 4 arranged distributed equidistantly around the circumference. The planetary rolling elements 4 are held so that they can rotate in two cage disks 5 that are provided on the ends and have corresponding bearing holes 6 in which non-profiled, cylindrical end journals 7 of the planetary rolling elements 4 engage. The cage disks 5 are connected to each other by means of connecting bars that are not shown in more detail and run axially and adjacent to the planetary rolling elements 4.

[0024] On the outer ring 2 there is a first tooth profile 8 comprising teeth 9 and circumferential grooves 10 formed between these teeth. Correspondingly, a tooth profile 11 is formed on the outside on the inner ring comprising teeth 12 and circumferential grooves 13 formed between these teeth. The tooth profiles 8 and 11 have an identical design, consequently also the corresponding groove construction.

[0025] Each planetary rolling element 4 is provided with a tooth profile 14 comprising teeth 15 and circumferential grooves 16 formed between these teeth. The tooth profile 14 engages in the tooth profiles 8 and 11 although a narrow gap is drawn for reasons of clarity. This means that the flanks of the teeth 15 roll on the flanks of the teeth 9 and 12, that is, a corresponding rolling contact is given.

[0026] For making the load distribution more uniform over the contact surfaces of the intermeshing teeth it should be assumed here that the tooth profile 14 of the planetary rolling elements 4 is profiled in a special way and is asymmetrical either with respect to the tooth height or the axial tooth distance, that is, the teeth do not all have the same height or the same distance to each other. In the following FIGS. 2-4, different embodiments for such a specific tooth profiling are given. The different embodiments make it possible to take the first tooth, viewed in the load direction, and optionally also subsequent teeth, somewhat from the load, that is, the load applied there is somewhat reduced and distributed more uniformly to the subsequent teeth.

[0027] In this context, FIG. 2 shows a first alternative construction of a planetary rolling element 4. In the shown embodiment, this has a total of eight teeth 15a, 15b, 15c, . . . 15h. As can be seen from FIG. 2, the respective teeth height or diameter of the individual teeth is not equal. In the illustrated example, the two end teeth 15a and 15h have the smallest diameter D.sub.1. The following teeth 15b and 15g, respectively, have somewhat larger diameter D.sub.2 accordingly. The following teeth 15c and 15f, in turn, have an even somewhat larger diameter D3, while the two middle teeth 15d and 15e have the largest diameter D4. Thus, overall a crowned outer shape is produced. Due to the reduced diameter and, in particular, its smallest diameter at the two outermost teeth 15a and 15h, these two teeth are loaded less, because the contact surface or the engagement in the tooth profile 8 and 11, respectively, is reduced. If, for example, the tooth 15a is the first tooth, viewed in the load direction, then it is loaded less than the following tooth 15b that is somewhat larger in diameter and consequently engages farther into the tooth profiles 8, 11, consequently is loaded somewhat stronger, which in turn is relevant for the somewhat larger dimension for the following teeth 15c, 15d. A load-dependent stress spike, consequently the greatest load, is no longer on the first tooth 15a, but is instead distributed more uniformly to all teeth. The loading on the outermost teeth is consequently reduced, resulting from the radial diameter variation of the teeth.

[0028] While FIG. 2 shows a crowned base shape of the planetary rolling element 4, FIG. 3 shows an embodiment in which the planetary rolling element 4 is likewise asymmetrical with respect to the tooth height, but is changed only on one side, so that consequently only a quasi one-sided crown shape is produced. It is assumed, in turn, that eight teeth 15a-15h are provided. Only the teeth 15a, 15b, and 15c have a reduced tooth diameter or tooth height, which increases from outside to inside, with the diameters D1 on tooth 15a, D2 on tooth 15b, and D3 on tooth 15c. The following teeth 15d-15h all have the same diameter D4. Obviously, the load is also made more uniform here, because, in particular, the tooth 15a, but also the teeth 15b and 15c are taken somewhat out from the load. However, here the offset inclination of the planets is minimized because the other teeth 15d-15h all have the same height.

[0029] Although multiple teeth have different heights in the shown embodiments, it is obviously also conceivable to somewhat reduce only the outermost tooth or the two outermost teeth in height. This can already provide an improvement in the load distribution.

[0030] FIG. 4 shows an embodiment of a planetary rolling element 4, in turn, comprising eight teeth 15a-15h, which all have the same diameter D, but in which the distance from tooth to tooth is not equal, that is, a varying pitch of the rows of teeth is given. The distances of the teeth to each other are indicated in FIG. 4 with d1 (distance from tooth 15a to tooth 15b), d2 (distance from tooth 15b to tooth 15c), . . . d7 (distance from tooth 15g to tooth 15h).

[0031] It should be assumed that the load is introduced, with respect to FIG. 4, from the left, that is, the load is first applied on the tooth 15d. The distance can then continuously increase, e.g., from left to right, that is: d1<d2<d3<d4<d5<d6<d7. Due to this continuously increasing tooth distance, it is also achieved that the recorded load is distributed more uniformly over the tooth contacts, consequently, load is removed, in particular, from the first tooth 15a.

[0032] As an alternative to the progressive pitch of the rows of teeth with increasing distance over all of the tooth distances, it is naturally also conceivable for only the first, the first two, or the first three tooth distances to have a reduced design and then to keep the tooth distances constant. In other words, for example, the following distance relationships could be given: d1<d2=d3=d4=d5=d6=d7 or d1<d2<d3=d4=d5=d6=d7 or d1<d2<d3<d4=d5=d6=d7. Also here, different construction variants are conceivable, like also for height or diameter variation.

[0033] It is understood that the corresponding diameter or distance variations equal a few hundredths or tenths of millimeters, wherein the actual changes are obviously oriented to the structural size and the load relationships to be expected.

[0034] FIG. 5 finally shows a partial view of a planetary roller bearing 1 in whichdifferently than in the previously described embodimentsthe tooth profiles 8 and 11 of the outer ring 2 and the inner ring 3 were changed. In the shown example it is assumed that the height of the teeth was varied. That is, the teeth 9a and 12awith reference to their respective groove baseboth have the same height, but are somewhat lower than the adjacent second teeth 9b and 12b, which are, in turn, somewhat lower than the teeth 9c and 12c. The respective tooth profile 8 or 11 can vary in height on both sidescomparable with the tooth profile of the planetary rolling element 4 according to FIG. 2so that a crowned structure is produced. Alternatively, the tooth profile 8 or 11 could also be structured as is shown for the planetary rolling element 4 according to FIG. 3. The curved structure is indicated by the dashed line.

[0035] The tooth profile of the respective profiled rolling element 4 would not be changed in this case, that is, all teeth would have the same height and all distances between two teeth would be equal. This is because the respective teeth of the two rings 2 are taken somewhat out of the loading.

[0036] As an alternative to the shown variation of the tooth height on the outer ring 2 and on the inner ring 3, there is naturally the option of varying the respective tooth distance, comparable with the planetary rolling element 4 from FIG. 4, that is, the distance of the tooth 9a to the tooth 9b or the tooth 12a to the tooth 12b is somewhat smaller than the distance of the tooth 9b to the tooth 9c or the tooth 12b to the tooth 12c, etc. The profiling can be changed similarly, as described with respect to the planetary rolling element 4 according to FIG. 4.

LIST OF REFERENCE NUMBERS

[0037] 1 Planetary roller bearing [0038] 2 Outer ring [0039] 3 Inner ring [0040] 4 Planetary rolling element [0041] 5 Cage disk [0042] 6 Bearing holes [0043] 7 End journal [0044] 8 Tooth profile [0045] 9 Tooth [0046] 10 Groove [0047] 11 Tooth profile [0048] 12 Tooth [0049] 13 Groove [0050] 14 Tooth profile [0051] 15 Tooth [0052] 16 Groove [0053] D Diameter [0054] d Distance