[0001] LOW MOMENT SELF-ALIGNING BEARING ASSEMBLY

[0002] This application claims the benefit of the earlier filing date of U.S.

Provisional Application No. 61/063,793, filed on February 4, 2008, which is incorporated by reference herein in its entirety.

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to a bearing and bearing pocket and, more particularly, to a self-aligning bearing assembly that prevents bearing rotation about a bearing bore axis when assembled with very low retainer force.

[0005] BACKGROUND OF THE INVENTION

[0006] The purpose of a self-aligning bearing assembly is to minimize the amount of bearing torque about its center of gravity and to prevent bearing rotation around its bore axis. Current assemblies with similar functionality rely on friction forces generated by a retainer, bearing and bearing pocket mating surfaces. The function of these assemblies is to prevent the bearing from spinning, however, if the bearing is allowed to spin, eventual lock up a motor can occur. In addition, a higher bearing moment is produced by these conventional assemblies that can have an adverse effect on motor performance when the bearing cannot self-align easily.

[0007] SUMMARY OF THE INVENTION

[0008] There is a need to provide a self-aligning bearing and housing bearing pocket that prevents bearing rotation about a bearing bore axis when assembled with very low retainer force.

[0009] An object of the invention is to fulfill the need referred to above. In accordance with the principles of an embodiment of the present invention, a bearing assembly includes a housing having a surface defining a bearing pocket. The housing includes at least a pair of ribs extending in the bearing pocket from the surface and towards a central axis of the bearing pocket, each rib defining rib edges. A bearing has a bore there-through and defines a bore axis. At least a portion of the bearing is received in the bearing pocket. The bearing has an outer surface and includes a plurality of pads extending outwardly from the outer surface. Each pad defines pad edges. A space is defined between adjacent pads. Each rib is disposed in a certain one of the spaces. Each space has a central portion of a certain width and each space tapers from the central portion to opposing end portions of the bearing such that a width of the space at the end portions is greater than the certain width so that the bearing can tilt with respect to the housing, with tilting of the bearing being limited upon engagement of certain pad edges with associated rib edges, while the bearing is substantially prevented from rotating about the bore axis due to the rib edges engaging associated pad edges near the central portion of the certain spaces. A retainer engages the housing so as to maintain the bearing in the bearing pocket without obstructing tilting of the bearing.

[0010] In accordance with another aspect of an embodiment, a self-aligning bearing assembly includes a housing having a surface defining a bearing pocket. The housing has housing surface features extending in the bearing pocket from the surface and towards a central axis of the bearing

pocket. A bearing has a bore there-through defining a bore axis. At least a portion of the bearing is received in the bearing pocket. The bearing has an outer surface and includes a plurality of bearing surface features extending outwardly from the outer surface. A space of varying width is defined between adjacent bearing surface features. Each housing surface feature is disposed in a certain one of the spaces. Each space is constructed and arranged such that the bearing can tilt with respect to the housing with tilting of the bearing being limited upon engagement of certain of the bearing surface features with associated housing surface features while the bearing is substantially prevented from rotating about the bore axis due to housing surface features engaging associated bearing surface features. A retainer engages with the housing so as to maintain the bearing in the bearing pocket without obstructing tilting of the bearing

[0011] Advantages, embodiments and further developments of the present invention can be found in the further subclaims and in the following description, referring to the drawings specification.

[0012] Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.

[0013] BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For a more complete understanding of the present invention and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings. The invention is explained in more detail below using exemplary embodiments which are specified in the schematic figures of the drawings, in which:

[0015] FIG. 1 is a sectional view of a self-aligning bearing assembly provided in accordance with an embodiment of the invention.

[0016] FIG. 2 is a view of a housing of the bearing assembly of FIG. 1 that includes a bearing pocket.

[0017] FIG. 3 is a view of the bearing of the bearing assembly of FIG. 1.

[0018] FIG. 4 is a view of the retainer of the bearing assembly of FIG. 1.

[0019] FIG. 5 is a transverse sectional view of the bearing received in the bearing pocket of the bearing assembly of FIG. 1.

[0020] FIG. 6 is a sectional view of the bearing assembly of the embodiment shown with the bearing at maximum tilt from a neutral position.

[0021] In all figures of the drawings elements, features and signals which are the same or at least have the same functionality have been provided with the same reference symbols, descriptions and abbreviations unless explicitly stated otherwise

[0022] DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT OF

THE PRESENT INVENTION

[0023] With reference to FIG. 1 a self-aligning bearing assembly is shown, generally indicated at 10, in accordance with the principles of an embodiment of the invention. The assembly 10 includes a housing 12 having a bearing pocket 14 therein. The assembly 10 also includes a retainer 18 for retaining the bearing 16 within the bearing pocket 14. The bearing assembly 10 is assembled in the same manner as prior art assemblies in that the bearing 16 is inserted into the bearing pocket 14

and the retainer 18 is pressed fit with respect to the housing 12 to capture the bearing 16.

[0024] With reference to FIG. 1 a self-aligning bearing assembly is shown, generally indicated at 10, in accordance with the principles of an embodiment of the invention. The assembly 10 includes a housing 12 having a bearing pocket 14 therein. The assembly 10 also includes a retainer 18 for retaining the bearing 16 within the bearing pocket 14. The bearing assembly 10 is assembled in the same manner as prior art assemblies in that the bearing 16 is inserted into the bearing pocket 14 and the retainer 18 is pressed fit with respect to the housing 12 to capture the bearing 16.

[0025] With reference to FIG. 2, the bearing pocket 14 is defined by a surface

20 ensuring that the bearing pocket 14 is a generally spherically-shaped cutout so as to receive at least a portion of the generally spherical bearing 16. Thus housing 12 includes housing surface features preferably in the form of at least a pair of ribs 22 extending in the bearing pocket from the surface 20 and towards a central axis A of the bearing pocket 14. In the embodiment, the two ribs 22 are disposed about 180° apart and have a length that extends substantially the entire depth of the bearing pocket 14. The proximal end of each rib 22 includes a radius portion 24 and each rib 22 has generally a constant width W (FIG. 6). The function of the ribs 22 will be explained below.

[0026] As shown in FIG. 2, the housing 12 includes a wall 26 that defines a generally cylindrical recess 28 generally adjacent to the bearing pocket 14. As shown in FIG. 1 , the retainer 18, in the form of a ring, is press fitted into the engagement with the wall 26 to maintain the bearing 16 in the bearing pocket 14, while permitting tilting of the bearing 16 with respect to the housing 12, as will be explained below.

[0027] With reference to FIG. 3, the bearing 16 has an outer spherical surface

30 and includes a bore 32 there-through that is constructed and

arranged to receive a shaft (not shown). The bearing 16 includes bearing surface features preferably in the form of a plurality of pads 34, extending outwardly from the outer spherical surface 30. Each pad 34 has a radius feature 36 at each opposing end. Features 36 and the radius portions 24 of the ribs 22 facilitate assembly, realigning the bearing 16 radially so it can be fully inserted inside the bearing pocket 14. Each pad 34 has a curved outer surface 35 that permits tilting of the bearing 16 within the generally spherically-shaped bearing pocket 14, as will be explained more fully below.

[0028] Pad edges 33 of adjacent pads 34 are separated by spaces 38 and each pad extends generally the entire height H (FIG. 1 ) of the bearing 16. In other words, the pads 34 extend in the direction of axis B. In the embodiment, four pads 34 are provided. As shown in FIG. 3, the width D of the spaces 38 are narrow near a central portion thereof and the width of the spaces 38 taper to a larger width dimension E near each opposing end of the bearing 16. This permits tilting of the bearing 16 with respect to the ribs 22 that are disposed in two of the spaces 38, yet prevents rotation of the bearing about the bore axis C, due to contact with the ribs 22 in the bearing pocket 14 near width D of the spaces 38 of the bearing 16.

[0029] FIG. 4 is a view of the retainer 18 that is ring-shaped and preferably generally U-shaped in cross-section (FIG. 1). The retainer 18 has a bore 39 there-through for receiving a shaft (not shown).

[0030] The components are assembled as shown in FIG. 1 , with the two ribs 22 being disposed in spaces 38 of the bearing 16 that are 180° apart. There are fours spaces 38 in the embodiment, but the ribs 22 are disposed in only two of the spaces 38. The bearing 16 thus has limited tilting motion inside the bearing pocket 14, limited only by the angle between the bearing pads 34. Pad edges 33 engage rib edges 40 to limit the tilting of the bearing 16. The amount of angular tilt exceeds the maximum

misalignment required by a motor shaft associated with the bearing 16. Therefore, the shaft and bearing bore axes will remain aligned. Thus, the shape of the pads 34 and the cooperation with the ribs 22 freely allow the bearing 16 to assume any position within the angle defined between pads 34 and yet prevent the bearing 16 from rotating about its bearing bore axis C. This allows the assembly of the bearing retainer 18 with minimal to zero pressure on the bearing 16. Due to this configuration, a very low torque is needed to self-align the bearing 16 when the shaft axis deviates from its initial position, decreasing drag on, for example, a motor armature employing the shaft.

[0031] FIG. 5 shows the ribs 22 in transverse section and with the bearing 16 in a neutral position.

[0032] FIG. 6 is a sectional view showing the bearing 16 at maximum tilt from the neutral position thereof.

[0033] The self-aligning bearing assembly 10 prevents bearing rotation about the bearing bore axis C when assembled with very low retainer force. This allows the bearing 16 to self-align with minimal amount of bearing rotational moment and yet, not spin in its bearing pocket 14 while a motor that employs the bearing assembly 10 is operational.

[0034] The bearing assembly 10 can be used in any application involving support of rotating elements that can produce some amount of lateral movement (misalignment) due to internal or external forces. Examples of some of the uses include motors, pulleys, and transmissions.

[0035] While embodiments and applications of this invention have been shown and described above, it should be apparent to those skilled in the art, that many more modifications (than mentioned above) are possible without departing from the inventive concept described herein. The invention, therefore, is not restricted except in the spirit of the appending claims. It is therefore intended that the foregoing detailed description is

to be regarded as illustrative rather than limiting and that it is understood that it is the following claims including all equivalents described in these claims that are intended to define the spirit and the scope of this invention. Nor is anything in the foregoing description intended to disavow the scope of the invention as claimed or any equivalents thereof.