Toroidal separator with lubricant channels for ball bearings

Abstract

A separator is provided for a 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, opposing first and second axial ends spaced apart along the centerline, an inner circumferential surface defining a central pocket sized to receive one of the plurality of balls, and an outer circumferential surface defining an outer periphery. A plurality of inner axial channels extend radially outward from the inner circumferential surface and a plurality of outer axial channels extend radially inward from the outer circumferential surface, each inner axial channel and each outer axial channel being configured to contain lubricant.Preferably, both the inner and outer axial channels are circumferentially spaced about the centerline and each channel extends fully axially between the first and second axial ends of the annular body.

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 the bodies as the bodies traverse a pitch circle defined between the inner and outer races of the bearing. In certain applications, particularly ball bearings, 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 all the balls.

[0003] Because end users often use significantly less lubricant than recommended by bearing manufacturers to avoid contamination from lubricant leakage, certain separators have been provided that are formed from a material, such as polytetrafluoroethylene ("PTFE"), which has inherent lubricating properties. However, such lubricious materials have relatively low wear resistance, leading to failure of separators formed from these materials. In contrast, separators formed from materials with higher wear resistance, such as polyetheretherketone ("PEEK"), are provided with satisfactory wear resistance but have increased friction and require a larger amount of lubricant to avoid failure. 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, first and second axial ends spaced apart along the centerline, an inner circumferential surface defining a central pocket sized to receive one of the plurality of balls, and an outer circumferential surface defining an outer periphery. A plurality of axial channels extend radially outward from the inner circumferential surface and / or extend radially inward from the outer circumferential surface, each axial channel configured to contain lubricant.

[0005] In yet another 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, first and second axial ends spaced apart along the centerline, an inner circumferential surface defining a central pocket sized to receive one of the plurality of balls, and an outer circumferential surface defining an outer periphery. A plurality of inner axial channels extend radially outward from the inner circumferential surface and a plurality of outer axial channels extend radially inward from the outer circumferential surface, each inner axial channel and each outer axial channel being 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, the number X being equal to half a value of N. Each separator comprises an annular body having a centerline, opposite first and second axial ends spaced apart along the centerline, an inner peripheral surface defining a central pocket sized to receive one of the balls, and an outer peripheral surface defining an outer periphery.A plurality of axial channels extend radially outward from the inner peripheral surface and / or extend radially inward from the outer peripheral surface, each axial channel being 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 an end elevational view of a bearing inner ring and three balls installed on the inner ring, showing a separator installed on one ball and disposed between two adjacent balls; Fig. 4 is a perspective view of the separator; Fig. 5 is a plan view of the separator; Fig. 6 is a side view of the separator; and Fig. Figure 7 is an exploded, enlarged view of a section of Fig. 5, which shows the lubricant arranged in axial channels of the separator. 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. 1-7 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 separators 10, the number X being equal to half a value of N and the separators 10 being arranged around every second ball 4 in the ball set 5.

[0010] The separator 10 essentially comprises a toroidal or annular body 12 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 further includes a plurality of axial channels 18 extending radially outward from the inner peripheral surface 14 and / or extending radially inward from the outer peripheral surface 16, each axial channel 18 being configured to contain lubricant L, as explained below.

[0011] As used herein, the term "axial channel" includes a channel 18 that extends entirely axially so as to be generally perpendicular to the first and second axial ends 12a, 12b of the body 12, or both partially axially and partially circumferentially so as to be generally inclined with respect to the first and second axial ends 12a, 12b (e.g., at a forty-five degree angle). Furthermore, the plurality of axial channels 18 may all be inclined or extend circumferentially in the same direction or may be arranged to extend in opposite circumferential directions such that each channel 18 may intersect one or more adjacent channels 18 or be separated by a circumferential gap (no alternative structure shown). Further, the plurality of axial channels 18 define a plurality of axial teeth 22, each axial tooth 22 being defined between two adjacent axial channels 18.Therefore, the annular body 12 preferably has the general appearance of a spur gear.

[0012] In addition, the inner peripheral surface 14 defines a central pocket 20 sized to receive one of the plurality of balls 4 and having an inner diameter ID ( Fig. 5) which is approximately equal to or slightly larger than the diameter of each ball 4. Thus, each ball 4 disposed in a separator 10 is retained therein, but is free to roll or rotate within the pocket 20. In addition, the outer peripheral surface 16 defines an outer periphery of the separator 10 and has an outer diameter OD ( Fig. 6), which is dimensioned so that a desired distance SD ( Fig. 2) between adjacent spheres 4. In other words, the ring-shaped body 12 has a radius R B , which extends from the center line L Cextends to the outer peripheral surface 16, thereby determining the minimum distance SD between the ball 4 arranged in the central pocket 20 and each of the two adjacent balls 4, as shown in Fig. 2 is specified.

[0013] As in Fig. 2, the first axial end 12a of the annular body 12 is adapted to be slidably disposed on an outer peripheral surface 2a of the bearing inner ring 2, and / or the second axial end 12b of the annular body 12 is adapted to be slidably disposed against an inner peripheral surface 3a of the bearing outer ring 3. Such contact with the annular surfaces 2a, 3a holds each separator 10, centrally disposed around the respective ball 4, in the pocket. 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.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.

[0014] Due to the guide surfaces 2a, 3a supporting either one or preferably both the inner and outer axial ends 12a, 12b, the separator 10 is held centrally around the respective ball 4 disposed in the pocket 20 when the ball 4 traverses the pitch circle PC. Preferably, the at least one guide surface 2a is provided by at least one and preferably two shoulders 2b of the inner ring 2, each providing one of two guide surfaces 2a and located adjacent to the bearing inner raceway R I Similarly, the at least one guide surface 4a is provided by at least one and preferably two shoulders 3b (only one shown) of the outer ring 3, which are located adjacent to the bearing outer raceway R OHowever, one or both of the guide surfaces 2a, 3a may be provided by another portion of the inner or outer bearing rings 2, 3, such as a single circumferentially extending guide projection (not shown) of the inner ring 2 axially projecting from the inner race R I spaced apart, and / or by a single guide projection (not shown) of the outer ring 3, which is axially separated from the outer race R O is spaced apart.

[0015] Preferably, the annular body 12 is formed from a molded polymeric material, most preferably comprising polyetheretherketone ("PEEK") and reinforcing fibers (e.g., glass fibers). As such, the separator 10 has a relatively high degree of wear resistance, and the lubricant L contained in the channels 18 more than compensates for the lack of inherent lubricating properties provided by other separator materials, such as polytetrafluoroethylene ("PTFE"). However, the body 12 may be formed from any other suitable polymeric materials, such as PTFE, nylon, etc., a ceramic material, or even a metallic material, such as aluminum.

[0016] With reference to the Fig. 4-6, the multiple axial channels 18 are circumferentially arranged around the center line L Cspaced around and preferably each have a first open end 18a at the first axial end 12a of the annular body 12 and a second open end 18b at the second axial end 12b of the annular body 12, as in Fig. 6. However, each channel 18 may alternatively be "closed" at one or both ends 18a, 18b, such that the channel(s) 18 extend only partially between the two ends 12a, 12b of the body 12 (structure not shown). Furthermore, the channels 18 preferably extend substantially axially, such that they are at least generally parallel to the centerline L C of the body and perpendicular to the axial ends 12a, 12b of the body, but may, as explained above, be angled, curved, or oriented in any desired configuration (no alternatives shown).

[0017] Preferably, the separator 10 includes axial channels 18 on both the inner peripheral surface 14 and the outer peripheral surface 16. In particular, the plurality of axial channels 18 includes a first set of inner axial channels 24 extending radially outward from the inner peripheral surface 14 and defining a set of inner axial teeth 25, and a second set of outer axial channels 26 extending radially inward from the outer peripheral surface 16 and defining a set of outer axial teeth 27.

[0018] As in Fig.7, a lubricant L, such as grease, heavy oil, etc., is preferably disposed in at least a portion of the inner axial channels 24 and in at least a portion of the outer axial channels 26 and is held in each of the channels 18 by surface tension. Therefore, the separator 10 preferably further comprises a quantity of lubricant L disposed in at least a portion of the axial channels 18 and preferably in all of the axial channels 18. By providing lubricant L in the channels 18, the lubricant L is transferred to all of the balls 4 during normal operation of the ball bearing 1.

[0019] In particular, the lubricant L within the inner axial channels 24 is distributed to the ball 4 arranged in the pocket 20, and the lubricant L within the outer axial channels 26 is transferred to each of the "loose" balls 4 adjacent to the respective separator 10 during the temporary contact between the ball 4 and the outer surface 16 of the separator. Due to the circumferential clearance between each "loose" ball 4 and the adjacent separators 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, although the direction can change, the circumferential play causes the loose balls 4 to temporarily contact both adjacent separators 10, creating a “pumping” effect that tends to pump lubricant from the separator channels 18 onto the loose balls 4 and subsequently onto the raceways R. I , R O to distribute.

[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 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 and spaced apart along the centerline, an inner peripheral surface defining a central pocket sized to receive one of the plurality of balls, an outer peripheral surface defining an outer periphery, and a plurality of axial channels extending radially outward from the inner peripheral surface and / or extending radially inward from the outer peripheral surface, each axial channel configured to contain lubricant. [2] The separator of claim 1, further comprising a lubricant contained in one or more of the axial channels. [3] The separator of claim 1, wherein the plurality of axial channels are circumferentially spaced about the centerline. [4] The separator of claim 1, wherein the plurality of axial channels comprises a first set of axial channels extending radially outward from the inner peripheral surface and a second set of axial channels extending radially inward from the outer peripheral surface. [5] The separator of claim 1, wherein each of the plurality of axial channels has a first open end at the first axial end of the annular body and a second open end at the second axial end of the annular body. [6] The separator of claim 1, wherein the plurality of axial channels define a plurality of axial teeth, each axial tooth being defined between two adjacent axial channels. [7] The separator of claim 1, wherein the annular body has a radius extending from the centerline to the outer peripheral surface, the radius defining a minimum spacing distance between the ball disposed in the central pocket and each of the two adjacent balls. [8] Separator according to claim 1, wherein the first axial end is configured to be slidably disposed on an outer peripheral surface of the bearing inner ring, and / or the second axial end 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 pocket. [9] The separator of claim 1, wherein the annular body is formed from a molded polymer material. [10] 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 and spaced apart along the centerline, an inner peripheral surface defining a central pocket sized to receive one of the plurality of balls, an outer peripheral surface defining an outer periphery, a plurality of inner axial channels extending radially outward from the inner peripheral surface, and a plurality of outer axial channels extending radially inward from the outer peripheral surface, each inner axial channel and each outer axial channel being configured to contain lubricant. [11] The separator of claim 10, wherein the plurality of inner axial channels are circumferentially spaced about the centerline and the plurality of outer axial channels are circumferentially spaced about the centerline. [12] The separator of claim 10, wherein each of the inner axial channels and each of the outer axial channels has a first open end at the first axial end of the annular body and a second open end at the second axial end of the annular body. [13] Separator according to claim 10, wherein: the plurality of inner axial channels define a plurality of inner axial teeth, each inner axial tooth being defined between two adjacent inner axial channels; and the plurality of outer axial channels define a plurality of outer axial teeth, each outer axial tooth being defined between two adjacent outer axial channels. [14] A separator according to claim 10, wherein the annular body has a radius extending from the center line to the outer peripheral surface, the radius defining a minimum spacing distance between the ball disposed in the central pocket and each of the two adjacent balls. [15] Separator according to claim 10, the first axial end is adapted to be slidably disposed on an outer peripheral surface of the bearing inner ring, and / or the second axial end is adapted 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 pocket. [16] A separator according to claim 10, wherein the annular body is formed from a molded polymer material. [17] Camp, including: 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, opposite first and second axial ends spaced apart along the centerline, an inner peripheral surface defining a central pocket sized to receive one of the balls, an outer peripheral surface defining an outer periphery, and a plurality of axial channels extending radially outward from the inner peripheral surface and / or extending radially inward from the outer peripheral surface, each axial channel being configured to contain lubricant. [18] A bearing according to claim 17, wherein the N separators are arranged around every second of the X balls.

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