Pivoting ball bearing system

A pivoting ball bearing. The ball bearing includes a first race and a second race and one or more rows of balls disposed therebetween. The first race includes a groove configured to have at least one row of balls track therein at a continuously variable circumferential tracking path while the first race rotates with respect to the second race. Pivoting of the first race with respect to the second race can occur by the balls shifting their circumferential tracking path within the groove of the first race. A collar on either the first race or the second race limits pivoting of the first race with respect to the second race.

FIELD OF THE INVENTION

The invention generally relates to ball bearing systems and specifically relates to pivoting ball bearing systems.

BACKGROUND

Conventional ball bearings typically include an outer race, an inner race, and balls interposed between the outer and inner races in a configuration that permits each race to rotate about a rotational axis. Conventional ball bearings are pivotally fixed such that the rotational axis of the outer race is collinear with the rotational axis of the inner race. Pivoting of the outer race with respect to the inner race, i.e., angling of the rotational axis of the outer race with respect to the rotational axis of the inner race, cannot occur without damaging the bearing. While the pivotal rigidity of conventional ball bearings is beneficial for many applications, it can also be limiting.

SUMMARY OF THE INVENTION

The present invention is directed to ball bearing systems that permit pivoting between races without damaging the ball bearing.

One version includes a ball bearing system comprising a first race having a first circumferential surface and a first groove spanning a circumference of the first circumferential surface, a second race having a second circumferential surface and at least one second groove spanning a circumference of the second circumference surface, and at least one row of balls disposed between the first race and the second race. The first groove is configured to have one of the at least one row of balls track therein at a continuously variable circumferential tracking path. Each of the at least one second groove is configured to have the one of the at least one row of balls track therein at a single circumferential tracking path. The first race defines a first rotational axis, the second race defines a second rotational axis, and pivoting of the first rotational axis with respect to the second rotational axis is accompanied by a compensating shift in tracking path of the at least one row of balls within the first race.

In preferred versions, the first groove has a width greater than a distance spanning the at least one second groove, the groove of the first race has a radius of curvature substantially greater than a radius of curvature of the balls tracking therein, and/or the at least one second groove has a radius of curvature substantially equal to a radius of curvature of the balls tracking therein.

In some versions, the first race is an outer race, and the first circumferential surface is an inwardly facing circumferential surface. In addition, the second race is an inner race, and the second circumferential surface is an outwardly facing circumferential surface.

In other versions, the first race is an inner race, and the first circumferential surface is an outwardly facing circumferential surface. In addition, the second race is an outer race, and the second circumferential surface is an inwardly facing circumferential surface.

The ball bearing preferably further includes at least one collar extending from a race toward an opposing race, wherein the race is selected from the group consisting of the first race and the second race. If the race is the first race the opposing race is the second race, and if the race is the second race the opposing race is the first race. The collar is configured to limit pivoting of the first rotational axis with respect to the second rotational axis at a predefined angle by contacting the opposing race or component connected thereto when the first rotational axis is pivoted with respect to the second rotational axis at the predefined angle.

In preferred versions, the collar defines a gap between itself and the opposing race when the first rotational axis and the second rotational axis are co-aligned. The collar preferably spans an entire circumference of a surface selected from the group consisting of the first circumferential surface and the second circumferential surface. The collar may comprise a continuous extension spanning an entire circumference of the surface. Alternatively, the collar may comprise individual extensions periodically disposed about an entire circumference of the surface. In some versions, the collar spans only a portion of a circumference of the surface. In one version, the collar limits pivoting of the first rotational axis with respect to the second rotational axis to an angle between about 0.25° and 5°.

Some versions further comprise at least one shield spanning an entire circumference of a surface selected from the group consisting of the first circumferential surface and the second circumferential surface, wherein the at least one collar, the at least one shield, and the at least one row of balls do not contact each other or the row of balls when the first rotational axis and the second rotational axis are co-aligned and also when the first rotational axis and the second rotational axis are angled at a maximum angle permitted by the at least one collar.

Some versions further comprise at least one shield spanning an entire circumference of a surface and extending toward an opposing surface. The surface is selected from the group consisting of the first circumferential surface and the second circumferential surface. If the surface is the first circumferential surface, the opposing surface is the second circumferential surface. If the surface is the second circumferential surface, the opposing surface is the first circumferential surface. At least one shield defines a gap between itself and the opposing surface when the first rotational axis and the second rotational axis are co-aligned and also when the first rotational axis and the second rotational axis are angled at a maximum angle permitted by the at least one collar.

Some versions comprise a first shield spanning the circumferential surface of the first race and a second shield spanning the circumferential surface of the second race. The first and second shields are both disposed beside one of two sides of the at least one row of balls. The first shield defines a gap between itself and the second race when the first rotational axis and the second rotational axis are co-aligned and also when the first rotational axis and the second rotational axis are angled at a maximum angle permitted by the at least one collar. The second shield defines a gap between itself and the first race when the first rotational axis and the second rotational axis are co-aligned and also when the first rotational axis and the second rotational axis are angled at a maximum angle permitted by the at least one collar.

In a specific version of the invention, the at least one second groove comprises two parallel grooves spanning the circumference of the second circumferential surface, and the at least one row of balls comprises two rows of balls. The first groove is configured to have both of the two rows of balls track therein at continuously variable circumferential tracking paths, and each of the two parallel grooves is configured to have each of the two rows of balls track therein at a single circumferential tracking path. The two parallel grooves are preferably mutually offset so that balls in a first of the two parallel grooves do not touch balls in a second of the two parallel grooves. The first groove preferably has a width greater than a distance spanning the two parallel grooves. In this version, pivoting of the first rotational axis with respect to the second rotational axis is accompanied by a compensating shift in tracking paths of each of the two rows of balls within the groove of the first race.

In some versions, the ball bearing system further comprises a ball spring plunger configured to insert within a connecting race selected from the group consisting of the first race or the second race and to exert a pressure on a device intended to be rotated. The pressure is sufficient to substantially prevent rotation between the device and the connecting race while allowing linear movement of the device through the connecting race.

The system may also further comprise a floating end and fixed end, wherein the device comprises an inner axle, the floating end comprises the connecting race, and the fixed end comprises a ball bearing linearly fixed to the inner axle.

The objects and advantages of the invention will appear more fully from the following detailed description of the preferred embodiment of the invention made in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to bearings20that permit both rotating and pivoting of an outer race24with respect to an inner race22. “Rotation” and grammatical variants thereof refer to movement of a first race with respect to a second race about a rotational axis. As shown inFIGS. 1-2, for example, inner race22rotates with respect to outer race24about rotational axis42, and outer race24rotates with respect to inner race22about rotational axis44. “Pivoting” and grammatical variants thereof refer to angling of the rotational axis of a first race with respect to the rotational axis of a second race. As shown inFIG. 1A, for example, inner race22is in a neutral position (e.g. concentric alignment) with respect to outer race24when the respective rotational axes42,44are collinear. As shown inFIGS. 1B and 2, by contrast, inner race22is pivoted with respect to outer race24when the respective rotational axes42,44are angled with respect to each other.

Exemplary bearings20of the present invention are shown inFIGS. 1A-2. The bearings20each include an inner race22and an outer race24. The inner race22and the outer race24each comprise a circumferential surface disposed about a rotational axis42,44, with the inner race22comprising an outwardly facing surface and the outer race24comprising an inwardly facing surface. In the exemplary bearings20, the inner race22and the outer race24both have substantially circumferential surfaces generally defining cylindrical shapes. However, other configurations, such as circumferential surfaces generally defining cone or other shapes, are possible.

The exemplary ball bearings20have two rows of balls26A,26B disposed between and in contact with the outwardly facing surface of the inner race22and the inwardly facing surface of the outer race24. The balls26A,26B facilitate rotation of the inner race22with respect to the outer race24. Each row of balls26A,26B preferably includes a sufficient number of balls to span the circumference of the outwardly facing surface of the inner race22and the circumference of the inwardly facing surface of the outer race24without touching other balls within the same row.

In the exemplary ball bearings20, the inner race22defines two parallel grooves23A,23B spanning the circumference of the outwardly facing surface of the inner race22. Each groove23A,23B defined by the inner race22is configured to have one of the two rows of balls26A,26B track therein as the inner race22rotates with respect to the outer race24. Each groove23A,23B defines a single tracking path in which each row of balls26A,26B contacts the outwardly facing surface of the inner race22while the inner race22rotates with respect to the outer race24. Each groove23A,23B preferably defines a perpendicular path with respect to the rotational axis42. The grooves23A,23B are preferably mutually offset to that the balls26A in the first groove23A do not contact the balls26B in the second groove23B. The grooves23A,23B may take a variety of configurations provided that they each define a single tracking path for the balls26A,26B. In a preferred version of the invention, each groove23A,23B comprises a rounded, concave indentation in the outwardly facing surface and further comprises a radius of curvature substantially equal to the radius of curvature of the balls26A,26B tracking therein. Other configurations, including a pair of rails that extend from the surface, V-shaped indentations in the surface, U-shaped indentations in the surface, and squared indentations in the surface, among others, are suitable.

The outer race24, by contrast, defines only one groove25spanning the circumference of its inwardly facing surface. The groove25has a width greater than the distance spanning the placement of the grooves23A,23B on the opposing surface. The groove25is configured to have both rows of balls26A,26B track therein as the inner race22rotates with respect to the outer race24. The groove25preferably permits the balls26A,26B to track at continuously variable tracking paths within the groove25as the inner race22rotates and pivots with respect to the outer race24. A preferred configuration of the groove25of the outer race24includes a rounded, concave shape with a radius of curvature substantially greater than the radius of curvature of the balls26A,26B tracking therein.

A ball bearing20with the structure and elements as described above permits pivoting of the inner race22with respect to the outer race24without damaging the ball bearing20. Such pivoting is depicted inFIGS. 1A and 1B.FIG. 1Ashows a ball bearing20with the inner race22and the outer race24concentrically aligned and, therefore, with rotational axes42,44aligned in a collinear manner. In this neutral position, each row of balls26A,26B tracks in a path on either side of the deepest part of the groove25in a shallower region thereof.

FIG. 1Bshows the same ball bearing20with the inner race22pivoted with respect to the outer race24. The pivoting is reflected in the rotational axis42of the inner race22being offset at a 2° angle with respect to the rotational axis44of the outer race24. The ball bearing20accommodates the pivoting by the two rows of balls26A,26B taking a different tracking path within the groove25defined by the outer race24while maintaining the same tracking path in the grooves23A,23B defined by the inner race22. Specifically, balls26A,26B closest to a portion of the ball bearing20in which the distance between the races24,26increases tracks away from a deeper part of the groove25and toward a shallower part of the groove25to compensate for the increased distance between the races24,26in that particular portion. Conversely, balls26A,26B closest to a portion of the ball bearing20in which the distance between the races24,26decreases tracks toward a deeper part of the groove25and away from a shallower part of the groove25to compensate for the decreased distance between the races24,26on that particular side. This shift in tracking paths results in side-to-side movement of the balls26A,26B with respect to the outer race24as they track about the circumference of the inwardly facing surface while maintaining a single path about the circumference of the outwardly facing surface of the inner race22(i.e., within each groove23A,23B). The shift in tracking paths upon pivoting is shown inFIG. 1Bwherein the tracking paths of the balls26A,26B on the top portion of the depicted bearing20shift from right to left with respect to the outer race24, and the tracking paths of the balls26A,26B on the bottom portion of the depicted bearing20shift from left to right with respect to the outer race24. Even in this pivoted position, each race22,24can rotate with respect to the other race about its own rotational axis42,44.

As described above, the exemplary bearings20shown inFIGS. 1A-2include two parallel grooves23A,23B defined in the inner race22a single groove25defined in the outer race24. A suitable variation comprises a ball bearing with the opposite configuration, i.e., in which the inner race defines a single groove on its outwardly facing surface and the outer race comprises two parallel grooves in its inwardly facing surface. The configurations and functioning of the elements and bearing as a whole in such a variation are identical to the exemplary bearing20except for the opposite placement of the respective grooves.

Yet other variations include only one row of balls disposed between the outer race24and the inner race22. In such a version, a single grove in the surface of one race provides a single circumferential tracking path for the single row of balls in the manner described above for either of groves23A or23B. A single groove in the surface of an opposed race is configured to have the single row of balls track therein at continuously variable circumferential tracking paths, preferably by being a rounded groove having a radius of curvature substantially greater than the radius of curvature of the balls tracking therein. A bearing comprising two rows of balls, however, is preferred as it provides for a stronger bearing upon pivoting.

Some versions of the invention comprise a rigid collar that limits pivoting of the inner race22with respect to the outer race24. The collar31limits the degree to which the inner race22pivots with respect to the outer race24by contacting the opposing race or a component connected thereto and “bottoming-out” at a pre-defined angle. An exemplary version is shown inFIG. 2, wherein a collar31is disposed on the inner race22and spans its entire circumference. In other versions, a collar31is disposed on the outer race24. In yet other versions, a collar31is disposed on each of the inner race22and the outer race24. The collar31may span the entire circumference of a race22,24or may be span only a portion thereof. Collars31spanning the entire circumference of a race22,24are preferred in bearings20contained in devices in which pivoting in all degrees of freedom can be expected. Collars31spanning only a portion of the circumference of a race22,24may be included in bearings20in devices in which pivoting in only certain directions is expected. The collar31in such versions is accordingly placed on a race22,24in fixed relation to the anticipated pivoting and is placed on a portion of the race22,24aligned with the direction of anticipated pivoting to oppose and limit pivoting in that direction. In versions in which the collar31spans the entire circumference of a race22,24, the collar31may comprise a continuous extension from the race22,24. Alternatively, the collar31may comprise individual extensions periodically disposed about the circumference of the race. In versions in which the collar31spans only a portion of the circumference of a race22,24, the collar31may include one or more discontinuous extensions from the race22,24.

The collar31may be configured to limit pivoting of the bearing20at an angle between respective rotational axes42,44of no greater than about 0.25°, 0.5°, 0.75°, 1°, 1.25°, 1.5°, 1.75°, 2°, 2.5°, 3°, 3.5°, 4°, 4.5°, 5° or more. The collar31is preferably configured to limit pivoting of the bearing20at an angle between respective rotational axes42,44between about 0.25° and 5°, more preferably between about 0.5° and 4°, and most preferably between about 1° and 3°. The collar31is preferably a steel collar. However, other hard, rigid materials are also suitable. In some versions of the invention, as shown inFIG. 2, a collar is disposed on only one side of the rows of balls26A,26B. In other versions of the invention, a collar is disposed on both sides of the rows of balls26A,26B. The collar31is preferably disposed on the race at a position such that the collar31contacts only the surface of the opposing race without contacting any other part of the race or the balls26A,26B between the races, whether in a neutral or pivoted position.

In some versions of the invention, the ball bearing20may comprise one or more shields27A,27B,28A,28B to protect the rows of balls26A,26B from dust or other contaminants. The shield27A,27B,28A,28B is an extension from the surface of a race that spans the circumference of the surface. The shield27A,27B,28A,28B preferably extends toward but does not contact the opposing race when the bearing20is in a neutral position (i.e., the axes of rotation42,44are in alignment), thereby defining a gap between itself and the opposing race. Each shield27A,27B,28A,28B also preferably defines a gap between itself and any neighboring element, such as another shield27A,27B,28A,28B, a collar31, or balls26A,26B, when in a neutral position. Such a configuration permits free rotation and a certain degree of pivoting of the inner race22with respect to the outer race24without undue friction or destruction of the shield27A,27B,28A,28B. The shields27A,27B,28A,28B may be made of a flexible material such as a plastic or rubber or may also be made of a rigid material such as a metal. A difference between a collar31and a shield27A,27B,28A,28B is that the collar31has a rigidity and strength to limit pivoting of the bearing20, whereas the shield27A,27B,28A,28B does not.

The exemplary versions of the bearing20shown inFIGS. 1A and 1Binclude shields27A,27B,28A,28B extending alongside each side of the rows of balls26A,26B from each of the inwardly facing surface of the outer race24and the outwardly facing surface of the inner race22. In the exemplary versions, the shields27A,27B extending from the inner race22are disposed in an exterior position with respect to the shields28A,28B extending from the outer race24. However, the relative positions of these shields may be reversed, wherein the shields27A,27B extending from the inner race22are disposed in an interior position with respect to the shields28A,28B extending from the outer race24. Furthermore, the bearing20may include only shields27A,27B extending from the inner race22or only shields28A,28B extending from the outer race24. The shown version with two sets of shields27A,27B,28A,28B on either side of the balls26A,26B and extending from opposing surfaces is preferred as it provides the greatest protection from contamination.

In some versions of the bearings20, the shields27A,27B,28A,28B may be included with one or more collars31. In other versions, one or more of the shields27A,27B,28A,28B may be replaced by one or more collars31. Such a version is shown inFIG. 2, wherein a collar31is included in place of a shield27B. Inclusion of a collar31with one or more shields27A,27B,28A,28B helps to protect the shields27A,27B,28A,28B from being damaged during pivoting. When a collar31is included with shields27A,27B,28A,28B, the shields27A,27B,28A,28B are preferably positioned and configured not to contact the opposing race, even when the bearing20is in a maximally pivoted position allowed by the collar31. Each shield27A,27B,28A,28B also still preferably defines a gap between itself and any neighboring element, such as another shield, a collar31, or balls26A,26B, when the bearing20is in a maximally pivoted position allowed by the collar31. In other versions, however, a shield27A,27B,28A,28B may be configured to contact neighboring elements when pivoted, particularly if they are comprised of a flexible material.

As shown inFIGS. 1A-2, the exemplary ball bearings20further comprise a lubrication port29and a connecting flange21. The lubrication port29comprises a hole through the outer race24that provides for injection of oil or grease. The connecting flange21provides for connecting the outer race24to devices intended to be rotated with respect to the inner race22, such as an outer axle44(seeFIG. 3). The connecting flange21preferably comprises an extension from a surface on a side of the outer race24opposite the inwardly facing face thereof. The connecting flange21is preferably continuously extends in a circumferential manner from the outer race24, but it may also include individual extensions periodically placed about the circumference of the outer race24. Other mechanisms or elements for connecting the outer race24to devices intended to be rotated with respect to the inner race22, or for connecting the inner race22to devices intended to be rotated with respect to the outer race24, are acceptable.

The bearings20may include at least one of several types of fasteners for attaching the races to devices to be rotated. One type of fastener is a set screw46. As shown inFIG. 3, the set screw46connects the inner race22to an inner axle42, the latter of which is intended to be rotated with respect to the outer race24and the attached outer axle44. The set screw46may comprise outer threads that mate with inner threads bored into the inner race22, such that the set screw46can be screwed into the inner race22to exert a pressure on a surface of the inner axle42and fix the inner race22with respect thereto. In some versions, the inner axle42may also have inner threads that mate with the outer threads of the set screw46so that the set screw46can screw through both the inner race22and the inner axle42. The inner axle42may also or additionally have an indentation configured to accept the set screw46therein.

Another type of fastener is a ball spring plunger50, which is shown inFIGS. 3 and 4. The exemplary ball spring plunger50shown inFIG. 4includes a threaded portion52and a spring53-loaded ball54extending from one of two ends. The threaded portion52screws into complimentary threads in the inner race22to a position such that only the spring53-loaded ball54contacts and exerts pressure on the inner axle42. The pressure of the spring53-loaded ball54secures the inner race22to the inner axle42to prevent rotation therebetween during normal usage while still providing some linear movement to accommodate linear expansion and contraction43of the inner axle42due to heat or misalignment. The inner axle42may comprise one or more indentations to accept the spring53-loaded ball54therein.

The bearings20described herein can be paired and employed in various rotational systems60. As shown inFIG. 3, a bearing20with a ball spring plunger50as a fastener is paired with a bearing20with a set screw46as a fastener. The fasteners connect the inner races22of the bearings20to an inner axle42. The outer races24are connected to an outer axle44, in part, via the connecting flange21. The bearing20fastened to the inner axle42with the set screw46constitutes a fixed end of the rotational system60, wherein the inner axle42, bearing20, and outer axle44are in fixed relation linearly (but not pivotally). The bearing20fastened to the inner axle42with the ball spring plunger50constitutes a floating end of the rotational system60, wherein the inner axle42can move linearly with respect to the bearing20. Bowing48of the inner axle42is accommodated by pivoting of the inner race22with respect to the outer race44, and linear expansion and contraction43is accommodated by linear movement of the inner axle42with respect to both the inner race22and the bearing20as a whole at the floating end. If bearings20with collars31are used, the collars31help prevent damage to the inner axle42and the bearing20due to bowing48.

In some versions, the rotational system60may include two fixed ends, with each bearing20being fastened with a set screw46. In other versions, the rotational system60may include two floating ends, with each bearing20being fastened with a ball spring plunger50.

In the exemplary rotational system60, the inner axle42comprises a single linear axle extending through both bearings20. In alternative versions, the inner axle42comprises two stub shafts (each ending at the dotted lines shown inFIG. 3), with each stub shaft extending through one of the two respective bearings20. Bowing48(or pivoting) of each of the stub shafts can be independently accommodated by the bearings20.

The elements and method steps described herein can be used in any combination whether explicitly described or not.

All patents, patent publications, and peer-reviewed publications (i.e., “references”) cited herein are expressly incorporated by reference to the same extent as if each individual reference were specifically and individually indicated as being incorporated by reference. In case of conflict between the present disclosure and the incorporated references, the present disclosure controls.

It is understood that the invention is not confined to the particular construction and arrangement of parts herein illustrated and described, but embraces such modified forms thereof as come within the scope of the following claims.