Self-adjusting ball bearing cage

A ball bearing assembly comprising first and second race members 4 and 6 formed with concave ball engaging surfaces 22 and 24 cooperating to define a path of movement 26 for balls 16, 18 and 20 located therebetween and a cage member 8 interposed between said race members 4 and 6 having a plurality of apertures 42, 44 and 46 formed therein, each containing a respective one of said balls 16, 18 and 20 and configured to engage said balls 16, 18 and 20 at an angle to said path of movement 26.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to ball bearings and is particularly directed to 
means for reducing friction and wear resulting from ball migration. 
2. Description of the Prior Art 
Ball bearings have been in use for many years to reduce friction between a 
first rotating member, such as a wheel, and a second member, such as a 
shaft, which may be stationary or may be rotating at a different rate than 
the first member. Ball bearings generally comprise inner and outer 
concentric race, each connected to a respective one of the members, and a 
plurality of balls, interposed between the race and maintained in place by 
a bearing cage, which is a strip of metal or other suitable material 
formed with a plurality of apertures of slightly greater diameter than the 
balls, with each of the.balls being positioned in a respective one of the 
apertures. 
In use, the motion of the rotating member is applied, through the adjacent 
race, to cause the balls to roll between the race, and the cage is carried 
with the balls. Unfortunately, due to individual differences, the balls 
tend to migrate in the cage apertures and will rub against the cage, 
causing increased friction and wear on the cage. Thus, especially in 
high-speed, high-load bearing packages, cage life presents a continuing 
problem. Numerous techniques have been proposed, heretofore, to reduce or 
eliminate cage wear. However, none of the prior art techniques have been 
entirely satisfactory. 
BRIEF SUMMARY AND OBJECTS OF INVENTION 
These disadvantages of the prior art are overcome with the present 
invention and a bearing cage is presented which counteracts migration of 
the balls and greatly reduces friction and cage wear. 
The advantages of the present invention are preferably attained by 
providing a bearing cage having apertures formed to engage the balls at an 
angle to the path of movement of the balls. This angular engagement causes 
a migrating ball to be forced slightly off its rolling path, which creates 
redundant opposed torques between the ball and the race requiring one of 
the ball-race contact points to slip torsionally. The ball-cage force 
vector passes through the geometric center of the ball, which is not in 
the same plane as the ball-race contact points. This causes additional 
torque which produces a preferential slip that relieves the ball-cage 
force and allows the ball to return to a neutral rolling condition, 
thereby relieving rubbing and wear between the ball and cage. 
Accordingly, it is an object of the present invention to provide improved 
ball bearings. 
Another object of the present invention is to provide ball bearing 
assemblies having reduced friction. 
A further object of the present invention is to provide ball bearing 
assemblies having prolonged cage life. 
A specific object of the present invention is to provide ball bearing 
asseablies wherein the cage apertures are formed to engage the balls at an 
angle to the path of movement of the balls. 
These and other objects and features of the present invention will be 
apparent from the following detailed description, taken with reference to 
the figures of the accompanying drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
A typical, prior-art ball bearing assembly is shown in FIG. 1, indicated 
generally at 2, having an outer race 4, an inner race 6, a bearing cage 8 
formed with a plurality of apertures, as seen at 10, 12 and 14, and a 
plurality of ball bearings, shown at 16, 18 and 20, each positioned in a 
respective one of the apertures 10, 12 and 14 of the cage 8. As best seen 
in FIG. 2, the race 4 and 6 are formed with concave ball-engaging surfaces 
22 and 24, which urge the balls 16, 18 and 20 into alignment with the 
rolling axis of the bearing, indicated at 26 in FIG. 3. With this aligning 
action, it will be seen that load forces from the race 4 and 6 will be 
applied through the center 28 of the ball, as indicated by arrows 30 and 
32 in FIGS. 1 and 2. When one of the races is moved, as represented by 
arrow 34 extending from race 4 in FIG. 1, this causes the balls 16, 18 and 
20 to roll and engage the cage 8. Due to individual differences, the balls 
16, 18 and 20 tend to migrate within their respective apertures 10, 12 and 
14, with some tending to engage the cage 8 at the forward edge of the 
aperture, as shown by ball 16 in FIGS. 1 and 3, and some to engage cage 8 
at the rearward edge of the aperture as shown by ball 18. In either case, 
however, the aligning action of the race surfaces 22 and 24 causes the 
balls 16 and 18 to engage the cage 8 at a constant point, as seen at 
points 36 and 38 in FIGS. 1 and 3, and this force is also applied through 
the center 28 of the ball, as indicated by arrow 40 in FIG. 1. 
Furthermore, as seen in FIG. 3, it is conventional for the apertures 10, 
12 and 14 of the cage 8 to be formed circular, with the centers of the 
apertures 10, 12 and 14 coinciding with the rolling axis 26 of the cage 8. 
This tends to reinforce the aligning of the balls 16, 18 and 20 and 
increases the friction and wear at the ball-cage contact points 36 and 38. 
As wearing of the cage 8 and balls 16, 18 and 20 occurs, the balls 16 and 
18 tend to bind against the ball-cage contact points 36 and 38 and cease 
rolling, which causes further increase in friction and wear at the points 
36 and 39 until the forces tending to roll the balls 16 and 18 exceed the 
friction at points 36 and 38, causing the balls 16 and 18 to slide. 
To overcome this problem, the present invention proposes to modify the cage 
8, as shown in FIG. 4 and 7, so that the cage apertures engage the balls 
at an angle to the rolling axis. As seen in FIG. 4, the cage 8 is formed 
with a plurality of alternately inverted triangular apertures 42, 44 and 
46, each receiving a respective one of the balls 16, 18 and 20. As seen in 
FIGS. 4, 5 and 6, when ball 16 migrates forward, it engages wall 48 of 
triangular aperture 42, which applies a force 50 through the center 28 of 
ball at an angle to the roll axis 26, tending to laterally displace ball 
16. This causes the race load forces 30 and 32 to be applied off-center of 
ball 16, as seen at 52 in FIGS. 4, 5 and 6. This off-center force 52 
produces a torque about the center 28 of ball 16, causing the ball 16 to 
rotate away from wall 48 and, thereby, relieving the friction between ball 
16 and cage 8. This rotation also serves to alter the orientation of ball 
16 which reduces the likelihood that ball 16 will re-engage wall 48 of 
aperture 42 at precisely the same contact point. Hence, wear will be 
distributed along wall 48 and the service life of cage 8 and ball 16 will 
be greatly extended. It will be seen from FIG. 5 that as the wall 48 
drives ball 16 laterally away from the roll axis 26, the application point 
52 of the race load forces will be moved farther away from the center 28 
of the ball 16 and, hence, the stronger will be the torque tending to 
rotate ball 16 away from wall 48. 
FIG. 7 shows an alternative form of the present invention. In this form, 
cage 8 is formed with a plurality of circular apertures 56, 58 and 60, 
each having its center laterally offset from the roll axis 26, as seen at 
62, 64 and 66. It will be apparent that walls of the eccentric apertures 
56, 58 and 60 will engage balls 16, 18 and 20 at an angle to the roll axis 
26 and will serve to cause a rotating torque to be developed in the balls 
16, 18 and 20, in the manner described above with respect to the 
triangular apertures of FIG. 4. 
Obviously, numerous variations and modifications can be made without 
departing from the present invention. Accordingly, it should be clearly 
understood that the forms of the present invention described above and 
shown in the accompanying drawings are illustrative only and are not 
intended to limit the scope of the invention.