CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No.

61/902,390, filed November 11, 2013, the entire contents of which are incorporated by reference herein.

BACKGROUND

[0002] The present invention relates to bearing assemblies, and more particularly to a bearing assembly including a bearing cage configured to collect lubricant and distribute the lubricant to a desired area during operation.

[0003] The majority of bearings have no means to direct lubricant flow to critical areas such as the rib-roller contact area. For some special applications, a system of manifolds and oil holes in the bearing inner or outer rings are used to direct the flow of lubricant to critical locations. This requires not only the addition of costly manufacturing processes to the bearing rings, but that special oil circulating systems be added to the shaft and/ or housings in the application.

SUMMARY

[0004] In one aspect, the invention provides a bearing assembly including an inner ring, an outer ring, and a plurality of rolling elements situated between the inner and outer rings. The plurality of rolling elements facilitates relative rotation between the inner and outer rings about an axis, and each rolling element has opposing axial end faces. A cage is situated between the inner and outer rings, the cage including a pair of axial end flanges and a plurality of bridges extending between the axial end flanges. At least one of the pair of axial end flanges of the cage includes at least one lubrication unit including an enclosed chamber, an inlet in fluid communication with the chamber, and an outlet in fluid communication with the chamber. The inlet is configured to take in liquid lubricant upon rotation of the cage and to direct the lubricant along a predominantly tangential path into the chamber. The outlet is configured to dispense the liquid lubricant from the chamber to one of the axial end faces of at least one of the plurality of rolling elements. [0005] In another aspect, the invention provides a cage for use in a rolling element bearing assembly. The cage includes a pair of ring-shaped axial end flanges and a plurality of bridges extending between the pair of axial end flanges. Rolling element pockets are defined between each adjacent pair of bridges. At least one of the pair of axial end flanges includes at least one lubrication unit including an enclosed chamber, an inlet in fluid communication with the chamber, and an outlet in fluid communication with the chamber. The inlet is configured to take in liquid lubricant upon rotation of the cage and to direct the lubricant along a predominantly tangential path into the chamber. The outlet is configured to dispense the liquid lubricant from the chamber to an interior axial end face of the axial end flange that at least partially defines one of the rolling element pockets.

[0006] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Fig. 1 is a front view of a bearing assembly according to one aspect of the invention.

[0008] Fig. 2 is a cross-sectional view, taken along line 2-2 of the bearing assembly of Fig. 1.

[0009] Fig. 3 is a front view of a bearing cage of the bearing assembly of Fig. 1.

[0010] Fig. 4 is a cross-sectional view, taken along line 4-4 of the bearing cage of Fig. 3.

[0011] Fig. 5 is a side view of the bearing cage of Fig. 3.

[0012] Fig. 6 is a cross-sectional view, taken along line 6-6 of the bearing cage of Fig. 5. [0013] Fig. 7 is a cross-sectional view, taken along line 7-7 of the bearing cage of Fig. 5. [0014] Fig. 8 is a cross-sectional view, taken along line 8-8 of the bearing cage of Fig. 6. DETAILED DESCRIPTION

[0015] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.

[0016] A bearing assembly 20 includes an inner ring 24, and outer ring 28, and a plurality of circumferentially-distributed rolling elements 32 positioned between the inner and outer rings 24, 28. The inner and outer rings 24, 28 share a common bearing axis A. Although a variety of applications are possible, the bearing assembly 20 provides low friction (i.e., rolling) support of a first component (e.g., a rotating shaft) within a second component (e.g., a stationary housing). The inner ring 24 includes a radially inner surface 26 secured with the first component, and the outer ring 28 includes a radially outer surface 30 secured with the second component. Each of the rolling elements 32 defines a rolling surface in contact with raceway surfaces of both the inner and outer rings 24, 28. In the illustrated construction, the rolling elements 32 have cylindrical rolling surfaces, but other constructions (i.e., tapered, spherical) are optional. A cage 36 extends circumferentially around the bearing axis A at a radial position that is between the inner ring 24 and the outer ring 28. The cage 36 includes a pair of opposed axial end flanges 38 and a plurality of bridges 40 extending generally axially between the two end flanges 38 (Fig. 2). A roller pocket is defined between each adjacent pair of bridges 40, and thus, the cage 36 maintains a predetermined spacing between all of the rolling elements 32. In one example, the bearing assembly 20 can be configured to accommodate a 60mm diameter shaft, to be accommodated in a 1 10mm housing aperture, and to have an axial depth of about 22mm, but alternate configurations are optional.

[0017] One or both of the inner and outer rings 24, 28 can include one or two ribs to retain the rolling elements 32 therein. For example, in the illustrated construction, the inner ring 24 includes a single rib 42 that extends radially outward to overlap with the axial end faces of the plurality of rolling elements 32 on a first axial end of the bearing assembly 20. Also, the outer ring 28 includes a pair of ribs 46 that extend radially inward to overlap with the axial end faces of the plurality of rolling elements 32 on both axial ends of the bearing assembly 20. One of skill in the art will recognize that a variety of different rib

configurations are optional. Wherever a rib-roller interface exists, a potential for wear (e.g., metal-on-metal) exists as the bearing assembly 20 is in operation and the rolling elements 32 travel circumferentially with respect to the inner and outer rings 24, 28. These interfaces can be a difficult location to ensure adequate lubrication during use. However, the cage 36 is provided with a lubrication collection and distribution system as described in further detail below.

[0018] A chamber 50 or series of chambers in one or both of the flanges 38 of the cage 36 are provided to store a supply of lubricant (e.g., liquid oil). An inlet orifice 54 in fluid communication with the chamber 50 has a geometry designed to promote accumulation of lubricant in the chamber 50 and a series of outlet orifices 58 are designed to allow

distribution of lubricant to a desired location (e.g., the rib-roller interfaces). The chamber 50 can be hollow, using only the geometry of the chamber 50, the inlet orifice 54, and the outlet orifices 58 to control the flow of lubricant, or alternately, the chambers 50 can be partially filled such that lubricant is forced to flow around and between obstacles, with the general size and placement of the obstacles being designed to control the lubricant flow. In any case, each chamber 50 can be an enclosed chamber (i.e., enclosed from the surroundings except for the respective inlet orifice 54 and outlet orifices 58, in contrast to an open channel or trough). The chamber 50 can be distinguished from the inlet orifice 54 and the outlet orifices 58 by having a larger cross-section than the inlet orifice 54 and the outlet orifices 58.

[0019] In the illustrated construction, the lubrication collection and distribution system of the cage 36 includes an independent inlet orifice 54, chamber 50, and series of outlet orifices 58 (i.e., a "lubrication unit") for each roller pocket of the cage 36. However, alternate arrangements are possible, such as a chamber and outlet orifices that extend along and are shared among a plurality of roller pockets, supplied by one or more inlet orifices, or the lubrication units can be provided at spaced intervals in a number less than the total number of roller pockets. The lubrication units can be provided in one or both of the cage flanges 38. As shown in Fig. 7, the inlet orifice 54 can be positioned at a radially outer circumferential surface of the cage flange 38. The inlet orifice 54 can be oriented at or adjacent the location of a bridge 40. However, in other constructions, the inlet orifice 54 can be arranged on another exterior cage surface (e.g., radially inner circumferential surface) and/or can be oriented at or adjacent the location of a roller pocket. The inlet orifice 54 can open radially inwardly into a passage with increasing cross-sectional area, such as a cone before connecting to the chamber 50. Thus, the inlet orifice 54 and the passage make up a tapered inlet, which takes lubricant in more readily than it allows lubricant to escape. The passage between the inlet orifice 54 and the chamber 50 can be arranged to extend along a direction that is neither purely radial nor purely tangential, but is predominantly tangential. [0020] In communication with the chamber 50, the outlet orifices 58 are arranged to extend generally axially toward a centerline of the bearing so that the lubricant is dispersed onto the axial end face(s) of the rolling elements 32. In other words, the outlet orifices 58 are provided in interior or inward-facing axial end surfaces 62 that at least partially define the rolling element pockets. This is best shown in Fig. 8. It can also be seen that each outlet orifice 58 is coupled to the chamber 50 via a tapered passage (i.e., tapering down in cross- sectional area toward the outlet orifice 58), making a tapered outlet. The shape can be conical, like that of the inlet. As shown, each tapered outlet defines an angle of about 10 degrees in cross-section. The tapering down toward the outlet orifice 58 can automatically meter the distribution rate of oil from the chamber 50. As shown, the chamber 50 can have a generally cylindrical shape (e.g., having a length of about 12.5mm for the 60mm inner diameter bearing described above). Such a chamber 50 can also have a diameter of about 2.0mm, and the end of the tapered inlet coupled to the chamber 50 can have a diameter of about 1.2mm. Thus, in this and other constructions, the cross-section of the chamber 50 can be larger than the cross section of the inlet passage from the inlet orifice 54 at any point along the length of the inlet passage from the inlet orifice 54 to the chamber 50. The length of the inlet passage between the inlet orifice 54 and the chamber 50 can be more than 30 percent of the chamber length and less than 50 percent of the chamber length.

[0021] It should be noted that the cage 36 is designed with an intended direction of rotation R (Figs. 6 and 7) within the outer ring 28. The direction of rotation R is defined as the direction in which rotation of the cage 36 results in the inlet orifice 54 leading the chamber 50. Thus, in a lubricated environment in which a sump of liquid oil at least partially bathes a lower portion of the bearing assembly 20 (Fig. 1), lubricant is automatically collected or scooped into all the inlet orifices 54 as they pass through the lubricant in the sump.

[0022] The chamber 50 and the orifices 54, 58 in the illustrated construction may be difficult or impossible to be created using conventional cage manufacturing techniques such as stamping, machining or molding. On the other hand, the geometry making up the chamber 50 and the orifices 54, 58 can be readily constructed using additive manufacturing techniques, in which the cage 36 is built by sequential layering of material. The layering material can include one or more polymers. The additive manufacturing process can create the voids including the inlet orifices 54, the chambers 50, and the outlet orifices 58 by leaving voids in the layers as laid, or by including an alternate, dissolvable (e.g., chemically dissolvable) material that is subsequently dissolved away after completion of the layering process.

[0023] Conventional bearing cages have no design features specifically to accumulate, transport, and deliver lubricant to a specific location within the bearing. By incorporating this capability into the cage 36, no expensive modifications to the bearing inner and/or outer rings 24, 28 or the shaft and/or housing are required.