Three-ring needle bearing

Details Three-ring needle bearing Three-ring needle bearing

1999-07-12

2001-04-24

Hannon, Thomas R. (Department: 3682)

Bearings

Rotary bearing

Antifriction bearing

C384S461000, C074S570200

Reexamination Certificate

active

06220760

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a three-ring needle bearing having two concentric, radially separated arrays of bearing needles.
A particular application for the three-ring bearing is to convert concentric rotation of a shaft into eccentric orbital motion of a mounting. This has particular application for use in a pump but is not limited for use only in a pump. The eccentric motion is produced by an eccentric ring between the two concentric arrays of needles.
Three-ring bearings are known from DE 196 32 167. However, that bearing unit is highly complex. It is necessary to incorporate a groove in the hole or bore in the eccentric center ring in order to fix the inner needle array axially in the groove.
Furthermore, the axial guides for the needle arrays may present problems. For example, the projection/groove connection between the cage for the inner needle array and the eccentric center ring may be worn. As a result, the inner array cage makes sliding contact on the sickle-shaped free space of the eccentrically designed molding on the outer race. In addition, the outer ring together with the outer needle array are secured axially only in one direction, so that the three-ring bearing can come apart during its installation.
Furthermore, the eccentric center ring must be provided with a threaded section for securing the torque transmission sleeve. The latter sleeve, as well as the mating piece, are equipped with a complex multiple tooth system, which does not axially fix the three-ring bearing with the electric motor.
SUMMARY OF THE INVENTION
The object of the invention is thus to provide a three-ring bearing which does not have the above disadvantages and, in particular, which is comprised of parts which can be manufactured easily, can be assembled easily, and which form a unit.
This object is achieved by producing the three-ring bearing using parts which block undesired axial motion of the bearing ring and the two bearing needle arrays. The bearing includes a central support shaft which is usually stationary. An inner annular needle array of axially extending bearing needles is around the central shaft and uses the central support shaft as an inner race. A rotatable eccentric center ring with a hole or bore through it defines the outer race for the inner needle array and it is also shaped for engaging the drive shaft of a motor, so that the eccentric center ring is rotated to provide orbital motion. An outer annular needle array of axially extending bearing needles is disposed outside the center ring and uses the exterior of the center ring as its inner race. An outer ring which is usually nonrotating is disposed outside the outer needle array and defines the outer ring. That outer ring has moldings at its axial ends for holding the outer needle array axially. Rotation of the drive shaft rotates the center ring, and the bearings enable the center ring to rotate with respect to the stationary central shaft and with respect to the nonrotating outer ring, and the outer ring moves in orbital eccentric motion.
A unit comprised of a plurality of parts is obtained simply by providing a U-shaped axial disk on that axial side of the three-ring bearing that faces away from the drive shaft from the electric motor. The U-shaped center part of the axial disk is seated with a push fit on the eccentric center ring of the bearing. It can thus be easily pushed on axially during assembly. That push fit prevents the parts from becoming loose. The outer ring of the three-ring needle bearing is fixed axially because after the radial projection of the axial disk has been installed, a molding on the outer ring is subsequently bent around, radially inwardly by plastic deformation. The outer ring, the outer needle array and the eccentric center ring thus form a unit which is easy to handle.
To fix the inner needle array axially, the axial disk also has a projection that projects radially inwardly. The cage of the inner needle array makes sliding contact with this projection. The axial disk causes the respective cages of the two needle arrays to make good, wear-free contact with the projections on this disk.


REFERENCES:
patent: 4861234 (1989-08-01), Joy et al.
patent: 5234270 (1993-08-01), Mathes
patent: 5632560 (1997-05-01), Dittenhofer
patent: 6078118 (2000-06-01), Reinartz et al.
patent: 19632167 (1998-02-01), None

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