BALL BEARING CAM FOLLOWER FOR AN ADJUSTABLE AIRCRAFT SEAT

Abstract

A cam follower assembly includes a ball bearing having an outer ring and an inner assembly which includes two or more segments. The inner assembly is disposed in the outer ring with a full complement of balls disposed therebetween. The outer ring and inner assembly each include a race having a gothic arch cross sectional configuration that causes the balls to roll on two portions of each race.

Claims

1. A cam follower assembly comprising: a ball bearing comprising: an outer ring having an interior area, the interior area being defined by an inner surface extending between a first axial end and a second axial end of the outer ring, the inner surface having a first radially inward facing bearing surface and a second radially inward facing bearing surface and a radially outward extending and inwardly facing first recessed surface therebetween; an inner assembly extending into the interior area, the inner assembly comprising a first inner segment extending from a third axial end to a fourth axial end thereof and a second inner segment extending from a fifth axial end to a sixth axial end thereof, the first inner segment having a first radially outward facing bearing surface and the second inner segment having a second radially outward facing bearing surface, the fourth axial end and the fifth axial end being abutted against each other and a radially inward extending and radially outward facing second recessed surface between the first radially outward facing bearing surface and the second radially outward facing bearing surface; and a plurality of balls positioned in the interior area between the outer ring and the inner assembly and in rolling engagement with the first radially inward facing bearing surface and the second radially inward facing bearing surface and the first radially outward facing bearing surface and the second radially outward facing bearing surface, the plurality of balls rollingly engaging each other and being spaced apart from the first recessed surface and the second recessed surface; a shaft having a bearing receiving portion and a mounting portion extending from the bearing receiving portion; and the ball bearing being disposed on the bearing receiving portion such that the inner assembly is secured to the shaft.

2. The cam follower assembly of claim 1, further comprising a shoulder positioned between the bearing receiving portion and the mounting portion, the shoulder extending radially outward from and circumferentially around the shaft and the second inner segment abutting an axial face of the shoulder.

3. The cam follower assembly of claim 1, wherein the first inner segment is secured to the shaft.

4. The cam follower assembly of claim 3, wherein the first inner segment is secured to the shaft by at least one of swaging, staking, pinning, a thermal fit and an interference press fit.

5. The cam follower assembly of claim 4, wherein the first inner segment is secured to the shaft by staking, wherein an axial looseness of the first inner segment relative to the outer ring is between about 0.0002 inches and about 0.0020 inches.

6. The cam follower assembly of claim 1, wherein the outer ring comprises a crowned exterior surface.

7. The cam follower assembly of claim 6, wherein the crowned surface comprises an arcuate shape having a radius of curvature.

8. The cam follower assembly of claim 1, further comprising at least one seal extending between the outer ring and the inner assembly.

9. The cam follower assembly of claim 1, wherein the mounting portion comprises a threaded area.

10. The cam follower assembly of claim 1, wherein each of the plurality of balls has a radius extending from a center of the ball, the centers of the plurality of balls tracing a reference circle around the inner assembly, the centers of the balls being aligned along a common radially extending reference plane; the first radially inward facing bearing surface having a first radius of curvature extending from a first origin located radially inward from the reference circle and axially offset from the reference plane towards the second inner segment, the second radially inward facing bearing surface having a second radius of curvature extending from a second origin located radially inward from the reference circle and axially offset from the reference plane towards the first inner segment, such that the first recessed surface, the first radially inward facing bearing surface and the second radially inward facing bearing surface form a first gothic arch cross sectional configuration; the first radially outward facing bearing surface having a third radius of curvature extending from a third origin located radially outward from the reference circle and axially offset from the reference plane towards the second inner segment, the second radially outward facing bearing surface having a fourth radius of curvature extending from a fourth origin located radially outward from the reference circle and axially offset from the reference plane towards the first inner segment, such that the second recessed surface, the first radially outward facing bearing surface and the second radially outward facing bearing surface form a second gothic arch cross section configuration; and wherein the first gothic arch and the second gothic arch are configured to accommodate external loads applied to the ball bearing due to misalignment.

11. A track roller bearing assembly comprising: a frame comprising: a base section having a first side and a second side opposite the first side; a connection section extending outwardly from the first side, the connection section having at least one first leg; a track extending from the second side, the track having a first bearing containment member and a second bearing containment member extending outwardly from the second side, the first bearing containment member and the second bearing containment member being spaced apart from one another, the first bearing containment member has a second leg extending therefrom, the second leg having a rolling engagement surface extending therefrom, the rolling engagement surface being substantially parallel to and facing the second side, the second bearing containment member having an opening extending therethrough; a cam follower assembly comprising: a ball bearing comprising: an outer ring having an exterior surface and an interior area, the interior area being defined by an inner surface extending between a first axial end and a second axial end of the outer ring, the inner surface having a first radially inward facing bearing surface and a second radially inward facing bearing surface and a radially outward extending and inwardly facing first recessed surface therebetween; an inner assembly extending into the interior area, the inner assembly comprising a first inner segment extending from a third axial end to a fourth axial end thereof and a second inner segment extending from a fifth axial end to a sixth axial end thereof, the first inner segment having a first radially outward facing bearing surface and the second inner segment having a second radially outward facing bearing surface, the fourth axial end and the fifth axial end being abutted against each other and a radially inward extending and radially outward facing second recessed surface between the first radially outward facing bearing surface and the second radially outward facing bearing surface; and a plurality of balls positioned in the interior area between and in rolling engagement with the first radially inward facing bearing surface and the second radially inward facing bearing surface and the first radially outward facing bearing surface and the second radially outward facing bearing surface, the plurality of balls rollingly engaging each other and being spaced apart from the first recessed surface and the second recessed surface; a shaft having a bearing receiving portion and a mounting portion extending from the bearing receiving portion; and the ball bearing being disposed on the bearing receiving area such that the inner assembly is secured to the shaft; the mounting portion extending through the opening in the second containment member such that the exterior surface of the outer ring rollingly engages the rolling engagement surface, the exterior surface being configured to accommodate misalignment of the frame relative to the ball bearing by maintaining rolling engagement of the exterior surface with the rolling engagement surface during such misalignment.

12. The track roller bearing assembly of claim 11, further comprising a shoulder positioned between the bearing receiving portion and the mounting portion, the shoulder extending radially outward from and circumferentially around the shaft and the second inner segment abutting an axial face of the shoulder.

13. The track roller bearing assembly of claim 11, wherein the first inner segment is secured to the shaft.

14. The track roller bearing assembly of claim 13, wherein the first inner segment is secured to the shaft by at least one of swaging, staking, pinning, a thermal fit and an interference press fit.

15. The track roller bearing assembly of claim 11, wherein the exterior surface of the outer ring is crowned.

16. The track roller bearing assembly of claim 15, wherein the crowned surface comprises an arcuate shape having a radius of curvature.

17. The track roller bearing assembly of claim 11, further comprising at least one seal extending between the outer ring and the inner assembly.

18. The track roller bearing assembly of claim 11, wherein the mounting portion comprises a threaded area.

19. The track roller bearing assembly of claim 11, wherein each of the plurality of balls has a radius extending from a center of the ball, the centers of the plurality of balls tracing a reference circle around the inner assembly, the centers of the balls being aligned along a common radially extending reference plane; the first radially inward facing bearing surface having a first radius of curvature extending from a first origin located radially inward from the reference circle and axially offset from the reference plane towards the second inner segment, the second radially inward facing bearing surface having a second radius of curvature extending from a second origin located radially inward from the reference circle and axially offset from the reference plane towards the first inner segment, such that the first recessed surface, the first radially inward facing bearing surface and the second radially inward facing bearing surface form a first gothic arch cross sectional configuration; the first radially outward facing bearing surface having a third radius of curvature extending from a third origin located radially outward from the reference circle and axially offset from the reference plane towards the second inner segment, the second radially outward facing bearing surface having a fourth radius of curvature extending from a fourth origin located radially outward from the reference circle and axially offset from the reference plane towards the first inner segment, such that the second recessed surface, the first radially outward facing bearing surface and the second radially outward facing bearing surface form a second gothic arch cross section configuration; and wherein the first gothic arch and the second gothic arch are configured to accommodate external loads applied to the ball bearing due to misalignment of the frame relative to the ball bearing.

20. A method for assembling a cam follower assembly, the method comprising: providing an outer ring, an inner assembly having at least two inner segments, a plurality of balls and a shaft having a shoulder formed thereon, each of the outer ring and at least two inner segments having a gothic arch shaped bearing surface therein; disposing a first of the at least two inner segments in the outer ring; installing a full complement of balls between the outer ring and a first of the at least two inner segments so that the balls engage a portion of the bearing surface; disposing a second of the at least two inner segments in the outer ring so that the balls are retained between the outer ring and the inner assembly; disposing the outer ring and inner assembly with the full complement of balls therein on the shaft such that one of the at least two inner segments engages the shoulder; and securing at least one of the at least two inner segments to the shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a split cross sectional and front view of the cam follower assembly of the present invention;

[0021] FIG. 2 is a perspective view of the cam follower assembly of FIG. 1 with a portion cut away to show a plurality of balls therein;

[0022] FIG. 3 is an enlarged view of an outer ring and a portion of a ball of a ball bearing employed in the cam follower assembly of the present invention;

[0023] FIG. 4 is an enlarged view of an inner assembly and a portion of a ball of a ball bearing employed in the cam follower assembly of the present invention;

[0024] FIG. 5 is a cross sectional view of the cam follower assembly of the present invention shown installed in an aircraft seat structure and track for a seat of an aircraft, shown in an unloaded state;

[0025] FIG. 6 is a cross sectional view of the cam follower assembly of the present invention shown installed in an aircraft structure and track for a seat of an aircraft, shown in an asymmetrically loaded state with the track misaligned relative to the ball bearing;

[0026] FIG. 7 is a perspective view of the cam follower assembly of FIG. 2 rollingly engaged with a surface of a track for a seat of an aircraft; and

[0027] FIG. 8 is partial split cross sectional and front view of the cam follower assembly of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0028] Referring to FIGS. 1 and 2, a cam follower assembly is generally designated by the numeral 10. The cam follower assembly 10 includes a ball bearing 20. The ball bearing 20 includes an outer ring 22 having an interior area 23. The interior area 23 is defined by an inner surface 24 extending between a first axial end 22A and a second axial end 22B of the outer ring 22. As best shown in FIG. 3, the inner surface 24 has a first radially inward facing bearing surface 26A and a second radially inward facing bearing surface 26B and a radially outward extending and inwardly facing first recessed surface 26C therebetween.

[0029] As shown in FIG. 1 the ball bearing 20 includes an inner assembly 50 that extends into (e.g., is disposed in) the interior area 23 of the outer ring 22. As best shown in FIG. 4, the inner assembly 50 includes a first inner segment 30 that extends from a third axial end 30A to a fourth axial end 30B thereof. The inner assembly 50 also includes a second inner segment 40 that extends from a fifth axial end 40A to a sixth axial end 40B thereof. The first inner segment 30 has a first radially outward facing bearing surface 32 and the second inner segment 40 has a second radially outward facing bearing surface 42. The fourth axial end 30B and the fifth axial end 40A are abutted against each other and form a juncture 34. A radially inward extending and radially outward facing second recessed surface 50C, 50C are formed between the first radially outward facing bearing surface 32 and the second radially outward facing bearing surface 42.

[0030] As shown in FIGS. 1, 3 and 4, in one embodiment, the ball bearing 20 includes a seal 29 that extends between the outer ring 22 and the inner assembly 50. As best seen in FIG. 1, the seal 29 includes an anchor portion 29A that is secured to the outer ring 22 and a sealing portion 29B that slidingly engages the inner assembly 50.

[0031] As shown in FIGS. 1 and 2, a plurality of balls 60 (i.e., a full complement of spherical balls) is positioned in the interior area 23 in rolling engagement with the first radially inward facing bearing surface 26A and the second radially inward facing bearing surface 26B and the first radially outward facing bearing surface 32 and the second radially outward facing bearing surface 42. The plurality of balls 60 are positioned between the outer ring 22 and the inner assembly 50. The plurality of balls 60 rollingly engage each other to form the full complement of balls with no spacers or gaps between the balls 60 to increase load capacity of the ball bearing 20 compared to other ball bearings having less than a full complement of balls. The balls 60 are spaced apart from the first recessed surface 26C and the second recessed surface 50C, 50C such that rolling of the balls 60 is not interrupted or otherwise disturbed by the juncture 34.

[0032] As shown in FIGS. 1 and 2, the cam follower assembly 10 includes a shaft 70 having a bearing receiving portion 72 and a mounting portion 74 extending from the bearing receiving portion 72. In one embodiment the mounting portion 74 includes a threaded area 74T (e.g., male thread as shown or a female thread, not shown, inside the mounting portion 74). The ball bearing 20 is disposed on the bearing receiving portion 72 such that the inner assembly 50 is secured to the shaft 70. The shaft 70 includes a shoulder 76 positioned between the bearing receiving portion 72 and the mounting portion 74. The shoulder 76 extends radially outward from and circumferentially around the shaft 70. The sixth axial end 40B of the second inner segment 40 abuts an axial face 78 of the shoulder 76.

[0033] As shown in FIG. 1, the first inner segment 30 is secured to the shaft 70 proximate a distal end 70D thereof, by staking. The second inner segment 40 is secured against the axial face 78 of the shoulder 76 by the first inner segment 30 being abutted against the second inner segment 40. While the first inner segment 30 is shown and described as being secured to the shaft 70 by staking, the present invention is not limited in this regard as the first inner segment 30 may be secured to the shaft 70 by swaging, staking, pinning, a thermal fit and/or an interference press fit.

[0034] As shown in FIG. 8 the first inner segment 30 is secured to the shaft 70 by staking at a staking area 80. If the first inner segment 30 is under staked (i.e., staked too loosely), it will result in separation of the first inner segment 30 and the second inner segment 40. In particular, if under staked, separation of the first inner segment 30 and the second inner segment 40 from one another occurs in directions D.sub.3 and D.sub.4, respectively. Directions D.sub.3 and D.sub.4 are parallel relative to the centerline C of the bearing 10. If the first inner segment 30 is over staked (i.e., staked too tightly), it will result in the first inner segment 30 and the second inner segment 40 moving towards each other in directions opposite of directions D.sub.3 and D.sub.4. It is preferred that the first inner segment 30 is secured to the shaft 70 by staking to create an axial looseness between the inner segments 30, 40 and the outer ring 22, as shown by distances D.sub.4 and D.sub.5. In one embodiment, the sum of distance D.sub.4 and distance D.sub.5 is between about 0.0002 inches to about 0.0020 inches. In one embodiment, a staking groove 20G is provided in the distal end 70D so that a portion 20Q of the distal end 70D is plastically deformed into the staking area 80 as indicated by the arrow Q10 in FIG. 8.

[0035] As best shown in FIG. 3, the outer ring 22 has a crowned exterior surface 22E, for example, an arcuate surface having a radius of curvature.

[0036] As best shown in FIG. 3, each of the plurality of balls 60 has a radius R1 extending from a center 60C of the ball 60. The centers 60C of the plurality of balls 60 trace a reference circle around the inner assembly 50. The centers 60C of the balls 60 are aligned along a common radially extending reference plane P1. The first radially inward facing bearing surface 26A has a first radius of curvature R2 that extends from a first origin C2 located radially inward from the reference circle and axially offset (i.e., in the direction of the arrow K1) from the reference plane P1 towards the second inner segment 40. The second radially inward facing bearing surface 26B has a second radius of curvature R3 that extends from a second origin C3 located radially inward from the reference circle and axially offset (i.e., in the direction of the arrow K2) from the reference plane P1 towards the first inner segment 30, such that the first recessed surface 26C, the first radially inward facing bearing surface 26A and the second radially inward facing bearing surface 26B form a first gothic arch cross sectional configuration.

[0037] As shown in FIG. 4, the first radially outward facing bearing surface 32 has a third radius of curvature R4 that extends from a third origin C4 located radially outward from the reference circle and axially offset (i.e., in the direction of the arrow K1) from the reference plane P1 towards the second inner segment 40. The second radially outward facing bearing surface 42 has a fourth radius of curvature R5 that extends from a fourth origin C5 located radially outward from the reference circle and axially offset (i.e., in the direction of the arrow K2) from the reference plane P1 towards the first inner segment 30, such that the second recessed surface 50C, 50C, the first radially outward facing bearing surface 32 and the second radially outward facing bearing surface 42 form a second gothic arch cross section configuration. The first gothic arch and the second gothic arch are configured to accommodate external loads applied to the ball bearing 20 due to misalignment as described herein.

[0038] As shown in FIG. 5, a track roller bearing assembly 100 includes a frame 90. The frame 90 has a base section 91 having a first side 91A and a second side 91B opposite the first side 91A. A connection section 92 extends outwardly from the first side 91A and has two legs 92A and 92B that form a channel 92C therebetween. The connection section 92 is secured to a seat rail 99 (e.g., a seat rail of a slidable aircraft seat) with fasteners 93. A track 94 extends from the second side 91B. The second side 91B is spaced apart from the exterior surface 22E of the outer ring 22 by a gap G5. The track 94 has a first bearing containment member 95A and a second bearing containment member 95B that extends outwardly from the second side 91B. The first bearing containment member 95A and the second bearing containment member 95B are spaced apart from one another. The first bearing containment member 95A has a leg 96 extending therefrom. The leg 96 has a rolling engagement surface 96E thereon. The rolling engagement surface 96E is substantially parallel to and faces the second side 91B. A portion of the second containment member 95B includes a lip 95B that extends away from the leg 96, towards the second side 91B. The second bearing containment member 95B has an opening 95C between the second bearing containment member 95B and the lip 95B.

[0039] As shown in FIGS. 5 and 6, the mounting portion 74 of the cam follower assembly 10 is secured to a structural seat member 98 of the aircraft. The track 94 guides the outer ring 22 of the cam follower assembly 10 as the ball bearing 20 rolls in the track 94 (i.e., the exterior surface 22E of the outer ring 22 in rolling contact with the rolling engagement surface 96E) when the structural seat member 98 moves during adjustment of the position of the aircraft seat. If loads on the seat are below a predetermined threshold, the rolling contact between the exterior surface 22E of the outer ring 22 and the rolling engagement surface 96E are aligned along the reference plane P1. The mounting portion 72 of the shaft 70 extends through the opening 95C between the second containment member 95B and the lip 95B, such that the exterior surface 22E of the outer ring 22 rollingly engages the rolling engagement surface 96E.

[0040] As shown in FIG. 6, the exterior surface 22E is configured to accommodate misalignment of the frame 90 relative to the ball bearing 20 by maintaining rolling engagement of the exterior surface 22E with the rolling engagement surface 96E during such misalignment. For example, as shown in FIG. 6, when a load is applied to the seat, a torque T1 is applied to the structural seat member 98 so that the frame 90 is misaligned relative to the ball bearing 20 such that a central plane P2 of the frame 90 is angularly displaced by an angle relative to the reference plane P1. With a load applied to the seat, rolling contact between the exterior surface 22E of the outer ring 22 and rolling engagement surface 96E are aligned along the reference plane P2. In the misaligned configuration or upon application of axial loads to the structural seat member 98, the axial ends 22A and 22B of the outer ring 22 slidingly engage and are retained by inside surfaces of the first bearing containment member 95A, the first bearing containment member 95B and the lip 95B. In one embodiment, one or more spacers (e.g., metal discs or rings or lubricious pads, rings or discs) are disposed between: 1) the axial end 22A and the inside surface of the first bearing containment member 95A; and/or 2) the axial end 22B and the inside surface of the second bearing containment member 95B and/or the lip 95B.

[0041] The ball bearing 20 accommodates the misalignment of the frame 90 relative to the ball bearing 20 by transferring load applied to the outer ring 22 by the seat rail 99 to a two point contact with the balls 60 and the outer ring 22 at circumferential lines of contact X1 and X2 and from the balls 60 and the inner assembly 50 at circumferential lines of contact Y1 and Y2 (shown in FIGS. 3 and 4).

[0042] The ball bearing 20 facilitates movement of the cam follower assembly 10 a distance along the rolling engagement surface 96E of the track 94. As shown in FIG. 7, the cam roller assembly 10 can move in a first direction D.sub.1 and a second direction D.sub.2 along the rolling engagement surface 96E. In one embodiment, the cam follower assembly 10 moves a distance between about 2.0 inches to about 3.0 inches in either first direction D.sub.1 or second direction D.sub.2. In another embodiment, the cam follower assembly 10 moves a distance between about 2.5 inches to about 3.0 inches in either first direction D.sub.1 or second direction D.sub.2. The ball bearing 20 is subject to multiple revolutions during use of the cam follower assembly 10. When the cam follower assembly 10 moves a distance between about 2.5 inches to about 3.0 inches, the outer ring 22 undergoes between about 1 to about 1.5 revolutions.

[0043] The present invention also includes a method for assembling a cam follower assembly 10. The method includes providing an outer ring 22, an inner assembly 50 having at least two inner segments 30, 40, a plurality of balls 60 and a shaft 70 having a shoulder 76 formed thereon. Each of the outer ring 22 and at least two inner segments 30, 40 has a gothic arch shaped bearing surface (i.e., the first gothic arch configuration including the first recessed surface 26C, the first radially inward facing bearing surface 26A and the second radially inward facing bearing surface 26B, as shown in FIG. 3; and the second gothic arch configuration including the second recessed surface 50C, 50C, the first radially outward facing bearing surface 32 and the second radially outward facing bearing surface 42, as shown in FIG. 4) therein. The method includes disposing the second inner segment 40 in the outer ring 22. The method includes installing a full complement of balls 60 between the outer ring 22 and the second inner segment 40 so that the balls 60 engage a portion of the bearing surface (e.g., the second radially outward facing bearing surface 42, the first radially inward facing bearing surface 26A and the second radially inward facing bearing surface 26B). The method includes disposing the first inner segment 30 in the outer ring 22 so that the balls 60 are retained between the outer ring 22 and the inner assembly 50 and so that the balls engage the first radially outward facing bearing surface 32. The method includes disposing the outer ring 22 and inner assembly 50 with the full complement of balls 60 therein on the shaft 70 such that the second inner segment 40 engages the shoulder 76 and the first inner segment and the second inner segment abut against each other. The method includes securing first inner segment 30 to the shaft 70.

[0044] Although the invention has been described with reference to particular embodiments thereof, it will be understood by one of ordinary skill in the art, upon a reading and understanding of the foregoing disclosure that numerous variations and alterations to the disclosed embodiments will fall within the scope of this invention and of the appended claims.