Low-wear toroidal separator for ball bearings

Abstract

A separator for a ball bearing comprises an annular body having a centerline, first and second opposing axial ends, and an inner peripheral surface defining a central pocket sized to receive one of the plurality of balls. Preferably, the annular body has a concave outer peripheral surface defining an annular channel and configured to contact at least one adjacent one of the balls along a curved line extending at least partially between the first and second axial ends or at a plurality of axially spaced contact portions. The outer peripheral surface has a radius of curvature approximately equal to the radius of curvature of an outer surface of each of the balls.Further, the annular body preferably also comprises a plurality of annular grooves axially spaced from one another, each annular groove extending radially inwardly from the concave outer peripheral surface and circumferentially around the centerline.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to bearings and, in particular, to separators for ball bearings.

[0002] Cages for ball bearings are well known and typically comprise an annular body with multiple circumferentially spaced pockets, each pocket housing a separate bearing ball. The cage establishes a desired spacing between adjacent balls and guides them as they traverse a pitch circle defined between the inner and outer races of the bearing. In certain applications, spacers are used instead of cages and typically comprise an annular body with a single pocket that fits around a single ball. Generally, multiple spacers are mounted around half the balls in a ball set, with every other ball contacting only two adjacent spacers, so that the spacers establish a desired spacing between the balls.

[0003] Typically, such separators have an outer circumferential surface that is either cylindrical or partially spherical. As a result, the "loose" balls interposed between each pair of adjacent separators tend to contact the outer surface of each separator at a specific point, concentrating the contact pressure and stress exerted on the separator and potentially leading to its eventual failure. Since end users often apply insufficient lubricant to bearings to prevent contamination from lubricant leaking from the bearing, separators can also fail due to insufficient lubrication. SUMMARY OF THE INVENTION

[0004] In one aspect, the present invention is a separator for a ball bearing, the ball bearing comprising inner and outer rings and a plurality of balls disposed between the inner and outer rings. The separator comprises an annular body having a centerline, opposite first and second axial ends, an inner peripheral surface defining a central pocket sized to receive one of the plurality of balls, and a concave outer peripheral surface. The concave outer peripheral surface defines an annular channel and is configured to contact at least one adjacent one of the balls at a plurality of contact portions spaced axially between the axial ends or along a curved line extending at least partially between the first and second axial ends.

[0005] In another aspect, the present invention is yet another separator for a ball bearing, the ball bearing comprising inner and outer races and a plurality of balls disposed between the inner and outer races. The separator comprises an annular body having a centerline, opposing first and second axial ends, an inner circumferential surface defining a central pocket sized to receive one of the plurality of balls, and an outer circumferential surface. A plurality of axially spaced annular grooves extend radially inwardly from the outer circumferential surface and circumferentially around the centerline, each groove configured to contain lubricant.

[0006] In another aspect, the present invention is a bearing assembly comprising an inner ring having a centerline, an outer ring disposed around the inner ring, a number N of balls disposed between the inner and outer rings and circumferentially spaced about the centerline to define a pitch circle, and a number X of separators, wherein the number X is equal to half a value of N. Each separator has an annular body having a centerline, opposite first and second axial ends, an inner circumferential surface defining a central pocket sized to receive one of the plurality of balls, and an outer circumferential surface.The outer peripheral surface is concave, defines an annular channel, and is configured to contact at least one adjacent one of the balls at a plurality of contact portions spaced axially from each other or along a curved line extending at least partially between the first and second axial ends, and / or a plurality of axially spaced annular grooves extend radially inwardly from the outer peripheral surface and circumferentially about the centerline, each groove configured to contain lubricant. BRIEF DESCRIPTION OF THE DIFFERENT VIEWS OF THE DRAWINGS

[0007] The foregoing summary, as well as the detailed description of the preferred embodiments of the present invention, will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the invention, there is shown in the drawings, which are schematically illustrated, embodiments that are presently preferred. It should be understood, however, that the present invention is not limited to the precise arrangements and instrumentalities shown. In the drawings: Fig. 1 is a radial cross-sectional view through a multi-separator bearing of the present invention, the bearing coupling a shaft to an outer member of a machine; Fig. 2 is an enlarged view of a section of Fig. 1; Fig. 3 is a plan view of a separator formed according to a first embodiment of the present invention; Fig. 4 is a side view of the separator of the first embodiment; Fig. 5 is a cross-sectional view through the separator of Fig. 4; Fig. 6 is an exploded, enlarged view of a portion of Fig. 4; Fig. 7 is a cross-sectional view of a separator formed according to a second embodiment of the present invention; and Fig. 8 is a side view of a separator formed according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] Certain terminology is used in the following description for convenience only and is not limiting. The words "inside," "inward," and "outside," "outward" refer to directions toward or away from a particular centerline or geometric center of a described element, respectively, the meaning of each being readily apparent from the context of the description. Further, the words "connected" and "coupled," as used herein, are intended to include direct connections between two elements with no other elements interposed therebetween and indirect connections between elements with one or more other elements interposed therebetween, respectively. The terminology includes the words specifically mentioned above, their derivatives, and words of similar import.

[0009] Referring now to the drawings in detail, wherein like numbers are used to designate like elements throughout, in Fig. 1-8 a toroidal separator 10 for a ball bearing 1 is shown, wherein the bearing 1 has an inner ring 2 with an inner race R I , an outer ring 3 with an outer race R O and a plurality of balls 4 arranged between the inner and outer rings 2, 3, forming a ball set 5. The ball bearing 1 has the function of rotatably coupling an inner element 6, e.g. a shaft, to an outer element 7, e.g. a housing or a hub, so that an element 6 or 7 can rotate about a central axis A C rotates when the balls 4 have a pitch circle PC defined between the rings 2, 3 ( Fig. 1). Preferably, the inner and outer elements 6, 7 are components or structural elements of a machine or element of a device E used in any suitable application. Furthermore, the bearing 1 preferably comprises a number N of balls 4 circumferentially arranged around the central axis A C spaced apart to define the pitch circle PC, and a number X of spacers 10, the number X being equal to half a value of N, and the spacers 10 being arranged around every other ball 4 in the ball set 5. For example, if the ball set 5 comprises twenty balls 4, the bearing 1 comprises ten spacers 10.

[0010] The separator 10 essentially comprises an annular body 12 or “toroid” with a center line L C , opposite first and second axial ends 12a, 12b, which extend axially along the center line L Cspaced apart, an inner peripheral surface 14 and an outer peripheral surface 16. The annular body 12 has a diametrical size to provide a spacing distance between adjacent balls 4, as further explained below. Preferably, the annular body 12 is formed from a molded polymeric material, preferably comprising polyetheretherketone ("PEEK") and reinforcing fibers (e.g., glass fibers), but may also be formed from any other suitable material.

[0011] Further, the inner circumferential surface 14 defines a central pocket 18 sized to receive one of the plurality of balls 4 and is preferably cylindrical. However, the inner surface 14 may alternatively be generally concave and extend radially outward into the body 12 to generally conform to the profile of the balls 4, or have any other suitable shape or contour. Furthermore, the first axial end 12a of the annular body 12 is configured to be slidably disposed on an outer circumferential surface 2a of the bearing inner ring 2, and / or the second axial end 12b of the annular body 12 is configured to be slidably disposed against an inner circumferential surface 3a of the bearing outer ring 3. Such contact with the surfaces 2a, 3a of the rings 2, 3 retains each separator 10, centrally disposed around the respective ball 4, in the pocket 18.

[0012] More specifically, the first axial end 12a provides an inner retaining surface adapted to be slidably disposed on at least one inner guide surface 2a of the bearing inner ring 2, and the second axial end 12b provides an outer retaining surface adapted to be slidably disposed on at least one outer guide surface 3a of the bearing outer ring 3. Such guide surfaces 2a, 3a are typically defined by a pair of annular shoulders 2b, 3b adjacent to the inner race R I or the outer race R O provided as in Fig. 2. In a typical application in which the axial ends of the bearing rings 2, 3 lie within vertical planes, the first axial end 12a slides against the outer guide surface 2a of the inner ring 2 when a separator 10 is arranged within the upper quadrants of the bearing 1, and the second axial end 12b slides against the inner guide surface 3a of the outer ring 3 when the separator 10 is arranged within the lower quadrants of the bearing 1. In either case, the separator 10 is held centrally around the respective ball 4 arranged in the pocket 18 as the ball 4 traverses the pitch circle PC due to the guide surfaces 2a, 3a supporting either the inner or outer axial ends 12a, 12b, and preferably both.

[0013] Referring to the Fig. 4-7, the outer peripheral surface 16 is preferably concave and extends radially inwardly into the annular body 12. The concave outer peripheral surface 16 defines an annular channel 20 extending circumferentially about the centerline L C As in Fig. 5, the annular body 12 has a radius R B , which extends from the center line L C extends to a radially innermost surface portion 17 of the concave outer peripheral surface 16, wherein the radius R B a minimum distance SD ( Fig. 2) between the ball 4 arranged in the central pocket 18 and each of the adjacent balls 4. Furthermore, the outer peripheral surface 16 is designed with such a concave contour to contact at least one adjacent one of the balls 4, preferably at a plurality of contact sections CS ( Fig. 4) arranged axially between the axial ends 12a, 12b or alternatively along a curved line CL ( Fig. 7) which extends at least partially between the first and second axial ends 12a, 12b.

[0014] More specifically, the concave outer peripheral surface 16 has a radius of curvature RC S ( Fig. 6), which is approximately equal to a radius of curvature RC B ( Fig. 5) an outer surface 4a of each of the spheres 4 which is equal to half the diameter (not specified) of each sphere 4. As used herein, “approximately equal” means a surface radius of curvature RC B , which either exactly corresponds to the radius of curvature RC B of the sphere or has a value that is not more than three percent greater than the radius of curvature RC Bof the ball. Due to this configuration, an adjacent ball 4 can contact the concave outer peripheral surface 16 along a curved line CL that extends at least partially, preferably almost completely, between the axial ends 12a, 12b of the annular body 12.

[0015] However, the annular body 12 preferably further comprises a plurality of annular grooves 22 spaced axially apart from one another, each annular groove 22 extending radially inwardly from the concave outer peripheral surface 16 and circumferentially about the center line L C Preferably, each groove 22 extends completely around the body centerline L C, so that it is continuous, but may alternatively be discontinuous and arcuate and either axially aligned or axially staggered. In any event, the annular body 12 with the grooves 22 thus also includes a plurality of annular ribs 24 that are axially spaced from one another, each groove 22 being defined between a separate pair of adjacent ribs 24. As best shown in Fig. 6, each of the plurality of axial ribs 24 has an outer peripheral surface 24a that is concave, the surfaces 24a collectively defining or providing the outer peripheral surface 16.

[0016] With particular reference to Fig. 5, each annular rib 24 provides a separate one of the axially spaced contact portions CS, as described above. Thus, when the annular body 12 includes the grooves 22, contact with each adjacent ball 4 occurs along one or more discrete contact portions CS, rather than along a curved line CL. Furthermore, due to the preferred concave outer surfaces 24a of the ribs 24, each contact portion CS is formed as an arcuate line segment, but may alternatively be formed as a separate point (not shown), for example, where the rib outer surfaces 24a are convex or partially spherical (not shown).

[0017] Furthermore, each of the plurality of annular grooves 22 is adapted to contain lubricants such as grease, heavy oil, etc., and as such, the separator 10 preferably further comprises a quantity of lubricant L disposed in at least one and preferably all of the annular grooves 22, such lubricant L being disposed in Fig. 6 is contained in a single groove 22. By providing lubricant L in the grooves 22, lubricant is transferred to each adjacent ball 4 during normal operation of the ball bearing 1.

[0018] More specifically, due to the circumferential play between each “loose” ball 4, i.e. a ball 4 not located in the pocket 18 of a separator 10, and each adjacent separator 10, the loose balls 4 alternately contact both adjacent separators 10 during the rotation of the ball set 5. That is, although the entire ball set 5 rolls around the bearing pitch circle PC in a single angular direction, the circumferential play causes the loose balls 4 to intermittently contact both adjacent separators 10, thereby creating a “pumping effect” that tends to pump lubricant from the separator grooves 22 to the loose balls 4 and thereafter to the raceways R I , R O and to distribute it to the balls 4 contained in the separator pockets 18.

[0019] With reference to Fig. 7-8, although the present separator 10 preferably includes both a concave outer peripheral surface 16 and a plurality of axially spaced annular grooves 22, the separator 10 may alternatively be provided with a “smooth” concave outer peripheral surface 16 without any grooves, as in Fig. 7, or with a cylindrical outer surface 16 with a plurality of axially spaced grooves 22, as in Fig. 8. As further alternatives, the separator 10 may be formed with only a single groove 22, with a plurality of circumferentially spaced arcuate grooves or discrete pockets, or with any other suitable configuration of recesses for receiving lubricants (no alternatives shown).

[0020] Representative, non-limiting examples of the present invention have been described in detail above with reference to the accompanying drawings. This detailed description is intended merely to provide those skilled in the art with further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention.

[0021] Furthermore, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in its broadest sense, and are instead taught only to particularly describe representative examples of the invention. Furthermore, various features of the representative examples described above, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated to provide additional useful embodiments of the present teachings.

[0022] All features disclosed in the description and / or claims are intended to be disclosed separately and independently of each other for the purpose of original written disclosure and for the purpose of limiting the claimed subject matter, regardless of the combinations of features in the embodiments and / or the claims. Furthermore, all ranges of values or indications of groups of entities are intended to disclose every possible intermediate value or entity for the purpose of original written disclosure and for the purpose of limiting the claimed subject matter. The invention is not limited to the embodiments described above, but may be varied within the scope of the following claims.

Claims

[1] A separator for a ball bearing, the ball bearing comprising an inner ring and an outer ring and a plurality of balls arranged between the inner ring and the outer ring, the separator comprising: an annular body having a centerline, first and second axial ends opposite each other, an inner circumferential surface defining a central pocket sized to receive one of the plurality of balls, and a concave outer peripheral surface defining an annular channel and is configured to contact at least one adjacent one of the balls at a plurality of contact portions spaced axially between the first and second axial ends or along a curved line extending at least partially between the first and second axial ends. [2] The separator according to claim 1, wherein the concave outer peripheral surface has a radius of curvature approximately equal to a radius of curvature of an outer surface of each of the balls. [3] The separator of claim 1, wherein the annular body further comprises a plurality of annular grooves axially spaced from one another, each annular groove extending radially inwardly from the concave outer peripheral surface and circumferentially about the centerline. [4] The separator according to claim 3, wherein each of the plurality of annular grooves is configured to contain lubricant. [5] The separator of claim 4, further comprising lubricant disposed in at least one of the annular grooves. [6] The separator of claim 3, wherein the annular body comprises a plurality of annular ribs axially spaced from one another, each groove being defined between a separate pair of adjacent ribs, each rib providing a separate one of the axially spaced contact portions. [7] The separator according to claim 1, wherein the inner peripheral surface is cylindrical. [8] The separator of claim 1, wherein the annular body has a radius extending from the centerline to a radially innermost surface portion of the concave outer peripheral surface, the radius defining a minimum spacing distance between the ball disposed in the central pocket and each of the adjacent balls. [9] Separator according to claim 1, wherein the first axial end of the annular body is formed to be slidably disposed on an outer peripheral surface of the bearing inner ring, and / or the second axial end of the annular body is formed to be slidably disposed on an inner peripheral surface of the bearing outer ring to hold the separator centrally around the ball disposed in the central pocket. [10] The separator of claim 1, wherein the annular body is formed from a molded polymer material. [11] A separator for a ball bearing, the ball bearing having an inner and an outer ring and a plurality of balls arranged between the inner and outer rings, the separator comprising: an annular body having a centerline, first and second axial ends opposite each other, an inner circumferential surface defining a central pocket sized to receive one of the plurality of balls, an outer peripheral surface and a plurality of axially spaced annular grooves, extending radially inwardly from the outer peripheral surface and circumferentially around the centerline, each groove being adapted to contain lubricant. [12] The separator of claim 11, wherein the outer peripheral surface is concave, defines an annular channel, and is configured to contact at least one adjacent one of the balls along a plurality of axially spaced contact portions. [13] The separator according to claim 12, wherein the concave outer peripheral surface has a radius of curvature approximately equal to a radius of curvature of an outer surface of each of the balls. [14] The separator of claim 12, wherein the annular body has a radius extending from the centerline to a radially innermost surface portion of the concave outer peripheral surface, the radius defining a minimum spacing distance between the ball disposed in the central pocket and each of the adjacent balls. [15] The separator of claim 11, further comprising lubricant disposed in at least one of the annular grooves. [16] The separator of claim 11, wherein the annular body comprises a plurality of annular ribs axially spaced from one another, each groove being defined between a separate pair of adjacent ribs, each rib providing a separate one of the axially spaced contact portions. [17] Separator according to claim 11, wherein the inner peripheral surface is cylindrical. [18] Separator according to claim 11, wherein the first axial end of the annular body is configured to be slidably disposed on an outer peripheral surface of the bearing inner ring, and / or the second axial end of the annular body is configured to be slidably disposed on an inner peripheral surface of the bearing outer ring to hold the separator centrally around the ball disposed in the central pocket. [19] The separator of claim 11, wherein the annular body is formed from a molded polymer material. [20] Ball bearings, comprising: an inner ring with a central axis; an outer ring arranged around the inner ring; a number N of balls arranged between the inner and outer rings and spaced circumferentially around the central axis to define a pitch circle; and a number X of separators, the number X being equal to half a value of N, each separator comprising an annular body with a center line, a first and a second axial end opposite each other, an inner peripheral surface defining a central pocket sized to receive one of the plurality of balls, and an outer peripheral surface; where at least one of the following : the outer peripheral surface is concave, defines an annular channel, and is configured to contact at least one adjacent one of the balls at a plurality of contact portions spaced axially from each other or along a curved line extending at least partially between the first and second axial ends; and a plurality of axially spaced annular grooves extending radially inwardly and circumferentially from the outer peripheral surface around the centerline, each groove being adapted to contain lubricant.

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