Bearing cage of a rolling-element bearing

Abstract

A bearing cage includes a circumferential ring element and an axial bridge that meet in a connection region, and the connection region includes a recess formed such that a thickness of the ring element in the connection region is less than a thickness of the ring element outside the connection region and such that a thickness of the bridge in the connection region is not less than a thickness of the bridge outside the connection region.

Claims

1. A bearing cage configured for use in a rolling-element bearing, the bearing cage comprising: a first ring element extending in a circumferential direction of the bearing cage, and a first bridge extending substantially in an axial direction of the bearing cage, wherein the first bridge is connected to the first ring element at a first connection region, wherein the first bridge has a first bridge first width in the circumferential direction of the bearing cage at a location outside the first connection region and a first bridge second width in the circumferential direction of the bearing at a location in the first connection region, wherein the first ring element has a first ring element first thickness in the axial direction of the bearing cage at a location outside the first connection region and a first ring element second thickness in the axial direction of the bearing cage at a location in the first connection region, and wherein the first connection region includes a recess, the recess being located in the first connection region relative to the first ring element and the first bridge such that the first ring element second thickness is less than the first ring element first thickness and such that the first bridge second width is not less than the first bridge first width.

2. The bearing cage according to claim 1, including a second ring element and a second bridge, the first bridge and the second bridge extending from the first ring element to the second element and defining a pocket configured to receive a rolling element, the first bridge being connected to the second ring element at a second connection region, wherein the first bridge has a first bridge third width in the circumferential direction of the bearing cage at a location in the second connection region, wherein the second ring element has a second ring element first thickness in the axial direction of the bearing cage at a location outside the second connection region and a second ring element second thickness in the axial direction of the bearing cage at a location in the second connection region, wherein the second ring element second thickness is less than the second ring element first thickness and the first bridge third width is not less than the first bridge first width.

3. The bearing cage according to claim 1, wherein the first ring element has a minimum ring element thickness at a recess location in the first connection region and wherein the first bridge has a maximum bridge width at the recess location.

4. The bearing cage according to claim 1, wherein the recess of the first connection region has a circumferential recess length and an axial recess depth, and wherein a ratio of the recess length to the recess depth is from 2 to 10.

5. The bearing cage according to claim 4, wherein the recess length extends over a substantially straight-extending recess base.

6. The bearing cage according to claim 1, wherein a ratio of a minimum bridge width outside the first connection region, to a maximum bridge width in the first connection region is from 0.5 to 0.9.

7. The bearing cage according to claim 1, wherein the first ring element has a first ring element maximum thickness at the location outside the first connection region and a first ring element minimum thickness at the location in the first connection region and wherein a ratio between the first ring element maximum thickness and the first ring element minimum thickness is from 1.05 to 1.4.

8. The bearing cage according to claim 1, wherein an enlargement of the bridge width in the first connection region is continuous and occurs along a curvature having a radius.

9. The bearing cage according to claim 8, wherein the bearing cage has a radially inner side and a radially outer side, wherein a radius of curvature located on the radially outer side is greater than a radius of curvature located on the radially inner side, and wherein the radius of curvature located on the radially outer side is formed by an application of a punching tool and the radius of curvature located on the radially inner side is formed by an application of a second stamping tool.

10. The bearing cage according to claim 8, wherein the bearing cage is manufactured from a metal plate having a metal-plate thickness (t), and wherein a radius of the curvature (r) of a radially outer side of the bearing cage is dependent on the metal plate thickness, and wherein the radius of curvature (r) satisfies the inequality: 0.2.Math.t+0.5r0.2.Math.t+0.9, wherein t and r are in measurements of a distance.

11. The bearing cage according to claim 1, wherein the bearing cage is manufactured from a metal plate.

12. A rolling-element bearing comprising: at least one inner ring, one outer ring, and roller elements disposed between the at least one inner ring and the outer ring, wherein the rolling elements are received in the bearing cage according to claim 1.

13. A rolling-element bearing according to claim 12, wherein the roller elements have a running surface configured to roll on the inner ring and the outer ring and to at least partially contact the first bridge, and a first and a second end surface, wherein the first end surface faces the first ring element and the second end surface faces the second ring element, wherein at a transition region between first end surface and the running surface an edge reduction is provided so that the first end surface is offset radially inward by an edge reduction value (k) of the running surface, and such that the running surface is shorter by the edge reduction value (k) than a total longitudinal extension of the roller elements between first and second end surface, wherein a recess depth of the recess on the bearing cage is defined by the edge reduction value (k), and wherein a ratio of the edge reduction value (k) to a recess depth is from 1.2 to 1.8.

14. The rolling-element bearing according to claim 13, wherein the cage is formed from a metal plate, wherein a curvature of the first bridge enlargement in the first connection region has a radius (r) defined by the edge reduction value (k), and wherein the inequality: 1.1.Math.kr1.4.Math.k is satisfied.

15. A bearing cage configured for use in a rolling-element bearing, the bearing cage comprising: a ring element extending in a circumferential direction of the bearing cage, a bridge extending substantially in an axial direction of the bearing cage, a recess extending into the ring element at a junction of the ring element and the bridge, wherein the recess does not extend into the bridge, wherein a width of a first portion of the bridge at the recess is greater than a width of a second portion the bridge at a location axially spaced from the recess.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 presents a schematic sectional view through a first exemplary embodiment of a bearing cage according to the disclosure;

(2) FIG. 2 presents a schematic sectional view through a bearing cage that includes a roller received therein;

(3) FIG. 3 presents a detailed view of a pocket of the cage of FIG. 1;

(4) FIG. 3a presents a detailed view of a radius of curvature of a recess of the pocket of the cage of FIG. 1, the detail being identified as detail section 3A of FIG. 3;

(5) FIG. 4 presents a detailed view of a pocket of a second exemplary embodiment of a cage according to the present disclosure; and

(6) FIGS. 5A and 5B are detail views of the pocket depicted in FIG. 4 with a roller received therein.

DETAILED DESCRIPTION

(7) In the following, identical or functionally equivalent elements are designated by the same reference numbers.

(8) A sectional view through a bearing cage 1 of a tapered roller bearing, including a first ring element 2 and a second ring element 4 that are connected to each other by a plurality of bridges 6 is illustrated in FIG. 1. Pockets 8 are thereby formed between first ring element 2, second ring element 4, and the bridges 6, in which pockets roller-shaped rolling elements (shown in FIGS. 2 and 5) are receivable. The receiving of a rolling element 10 is depicted in FIG. 2, wherein in addition the ring element 2 and, in sectional view, the bridges 6 are visible. As can further be seen in FIG. 2, the rolling element 10 is received in the pocket 8. Even though a tapered roller bearing is depicted in the figures, other rolling-element bearings can be equipped with a cage that is similarly equipped in the transition region between bridge and ring. The bearing cage itself is usually manufactured from a metal plate or plastic.

(9) Furthermore, as can be seen in the sectional view of FIG. 1 the bearing cage 1 has a metal-plate thickness t. Due to the novel design of the bearing cage 1 described below this metal-plate thickness t can be reduced without the structural load-bearing capacity of the bearing cage 1 being impaired.

(10) For this purpose the bearing cage 1 further includes a recess 14-1, 14-2 in a connection region 12 between the bridge 6 and the first and/or second ring element 2; 4. This recess 14-1, 14-2 is configured here such that in this region a reduction of the ring element thickness R is effected specifically to a minimum ring element thickness R.sub.min, but an enlargement of the bridge thickness S is effected specifically to a maximum bridge width S.sub.max. Here a ring element thickness in the axial direction is measured with respect to an axis of rotation A of the bearing cage 1, while a bridge width is measured in the circumferential direction U of the bearing cage. As can further be seen in FIG. 1 the recess 14-1, 14-2 is configured such that a maximum bridge widening S.sub.max is formed at the location at which the ring element thickness R.sub.min is minimal.

(11) Here it has proven particularly advantageous if a ratio between maximum ring element thickness R.sub.max and minimum ring element thickness R.sub.min falls in the range between 1.05 and 1.4:
1.05R.sub.max/R.sub.min1.4

(12) Furthermore it is advantageous if the ratio of the minimum bridge width S.sub.min to the maximum bridge width S.sub.max falls between 0.5 and 0.9:
0.5S.sub.min/S.sub.max0.9

(13) In the depicted bearing cage of a tapered roller bearing, the minimum bridge width S.sub.min and the maximum ring element thickness R.sub.max are preferably measured in the center of the pocket 8. With cages of other rolling-element bearings the values can be determined at other points.

(14) Since in the transition region between the bridge 6 and the first or second ring element 2; 4 no tapering of the bridge width but rather an enlargement of the bridge width occurs, the weakening of the bearing cage 1 that occurs due to the introduction of the recess into the ring element thickness can be compensated for.

(15) Two different designs for the pocket shape 8 are shown respectively in FIGS. 3 and 4. Only one pocket is respectively depicted here. The bridge and ring element are depicted only in section and each show their inner edges 18-1, 18-2 (ring element) or 16-1, 16-2 (bridges) so that no ring element thickness or bridge width is visible here. Furthermore, FIGS. 3 and 4 show in particular in the enlarged cutouts that the recess 14-1 or 14-2 respectively has a certain recess length x in the circumferential direction and a recess depth y. It has further proven here that is advantageous if the ratio between recess length x and recess depth y falls in the range from 2 to 10:
2x/y10

(16) In order to provide a particularly large ratio between recess length x and recess depth y, as further depicted in FIG. 4 the recess 14 can include a recess base 20 that extends essentially parallel to the inner edge 18 of the ring element 2, 4. Due to this straight-extending recess base 20 the recess length x can be increased in order to adapt the bearing cage to the requirements of the rolling-element bearing. Such an enlargement of the recess length x is advantageous in particular with larger metal-plate thicknesses t. Furthermore the enlarged cutouts show that the transition from the recess 14 to the inner edge 18 of the pocket is effected via an essentially straight section 22 that is angled at an angle with respect to the inner edge 18. The angle preferably falls in the range of 10-25.

(17) Furthermore it can be seen in FIGS. 3 and 4 that the transition from minimum ring element thickness R.sub.min to maximum bridge width S.sub.max occurs continuously and along a curvature having radius r.

(18) Here the inventors have further recognized that a particularly stable cage can be obtained if the metal-plate thickness t is set in relation to the radius r such that it is true that:
0.2.Math.t+0.5r0.2.Math.t+0.9

(19) wherein t represents a thickness, measured in units of a dimension and

(20) wherein r represents a radius, measured in units of a dimension.

(21) Furthermore FIG. 5A shows an exemplary embodiment of the cage as in FIG. 4 with roller 10 received therein. As can further be seen in FIGS. 5A and 5B, the roller 10 includes a running surface 24, via which the roller 10 rolls along on the inner or outer ring of the rolling-element bearing (not depicted) and is guided by the bridge 6. Furthermore the roller 10 includes a first end surface 26 that is associated with the first ring element 2, and a second end surface 28 that is associated with the second ring element 4. Both end surfaces 26, 28 interact with the inner side 18 of the ring elements 2, 4. As can further be seen from FIGS. 5A and 5B, each roller 10 includes an edge reduction 30-1, 30-2, 30-3, 30-4 at the transition region between running surface 24 and the end surfaces 26, 28. One of these edge reductions 30-1 is depicted enlarged in FIG. 5. Here the running surface or the first or second end surface is respectively reduced by an edge reduction value k. As depicted, the edge reduction is preferably symmetrical.

(22) The edge reduction value k in turn determines the recess depth y, wherein a ratio of edge reduction value k to recess depth y falls in the range between 1.2 and 1.8.
1.2k/y1.8

(23) It can be ensured by this relationship that an optimal balance is achieved between the edge reduction k and the recess y, so that no interference arises between roller 10 and cage 1. It can thereby also be ensured that a sufficiently large curvature angle r or an enlargement of the bridge widths S can be effected without the roller 10 jamming in the cage 1. For the ratio between edge reduction value and radius the following relationships have been recognized as advantageous:
1.1.Math.kr1.4.Math.k

(24) Furthermore it can be advantageous if the cage has a different radius on its radially outer surface 32 (see FIG. 1) than on its radially inner surface 34 (see FIG. 1). These different radii r.sub.i, r.sub.a are identified in an enlarged section of FIG. 3 illustrated in FIG. 3A. However, it is advantageous if the outer radius r.sub.a of the curvature is greater than the inner radius r.sub.i of the curvature, and the outer radius r.sub.a is usually provided by a first tool and the inner radius r.sub.i is provided by a second tool. More specifically, the bearing cage 1 has a radially inner side 34 and a radially outer side 32, wherein a radius of curvature r.sub.a located on the radially outer side 32 is greater than a radius of curvature r.sub.i, located on the radially inner side 34 and wherein the radius of curvature r.sub.a located on the radially outer side 32 is formed by an application of a punching tool and the radius of curvature r.sub.a located on the radially inner side 34 is formed by an application of a second stamping tool. Thus it is advantageous; for example, if the outer radius r.sub.a is provided by punching of a metal plate, while the inner radius r.sub.i is formed by a subsequent stamping treatment of the bearing cage. The inner or outer radius r.sub.a, r.sub.i are also preferably determined via the edge reduction value k of the roller 10 to be received, wherein in particular the following relationships have proven as advantageous:
1.1r.sub.a1.4.Math.k or 0.8.Math.kr.sub.i1.0.Math.k

(25) Overall, using the disclosed bearing cage design a bearing cage can be provided whose structural load capacity is increased such that even a reduction of the metal-plate thickness t of the cage 1 is possible with identical load values compared to a standard design. In addition, interference and thus jamming of the rollers 10 in the cage pockets 8 can be reliably prevented despite increased radius of curvature r between bridge 6 and ring element 2, 4. At the same time, by adapting the recess length x and recess depth y the cage 1 can be optimally adapted to the desired properties.

REFERENCE NUMBER LIST

(26) Ref No. Description

(27) 1 Bearing cage 2 First ring element 4 Second ring element 6 Bridge 8 Pocket 10 Roller 12 Connection region 14-1 Recess 14-2 Recess 16-1 Bridge inner edge (bearing cage inner surface) 16-1a Bridge inner edge (bearing cage outer surface) 16-2 Bridge inner edge 18 Ring element inner edge 18-1 Ring element inner edge (bearing cage inner surface) 18-2 Ring element inner edge 18-2a Ring element inner edge (bearing cage outer surface) 20 Recess base 22 Transition between recess and inner edge of the ring element 24 Running surface of the roller 26, 28 End surface of the roller 30-1 Edge reduction 30-2 Edge reduction 30-3 Edge reduction 30-4 Edge reduction 32 Radially outer side/edge 34 Radially inner side angle r Radius of curvature r.sub.a radius of curvature (bearing cage outer surface) r.sub.i radius of curvature (bearing cage inner surface) k Edge reduction value t Metal-plate thickness S Bridge width S.sub.min Bridge width (minimum) S.sub.max Bridge width (maximum) R Ring element thickness R.sub.min Ring element thickness (minimum) R.sub.max Ring element thickness (maximum) x Recess length y Recess depth u Circumferential direction A Axial direction