Machine element or mechanism – Mechanical movements – Reciprocating or oscillating to or from alternating rotary
Patent
1998-01-15
2000-04-25
Bucci, David A.
Machine element or mechanism
Mechanical movements
Reciprocating or oscillating to or from alternating rotary
744248R, 74459, F16H 2702, F16H 118, F16H 5517
Patent
active
060530634
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns a worm gear for transforming a rotary motion into a reciprocating (linear) motion, comprising a threaded spindle which is mounted for rotation in a gear ring nut, a profiled gear ring engaging into a screw thread of the threaded spindle at one peripheral point, which gear ring surrounds the threaded spindle, is arranged eccentric to a spindle axis and fixed on an inner ring of a ball bearing which surrounds the gear ring.
A worm gear of this type is known from EP-PS 0 122 596 and comprises two gear rings with ball bearings whose outer rings are arranged in special rolling bearing receiving elements within a housing. The gear rings surround the threaded spindle. The bearings which serve as a radial support for the gear ring nut on the threaded spindle are needle bearings. The necessity of using a housing and arranging the ball bearings and the rolling bearing receiving elements in the housing results in a structure which is rather complicated on the whole.
SUMMARY OF THE INVENTION
The object of the invention is to create an easy-to-mount worm gear with a simplified structure.
The invention achieves this object by the fact that, within the gear ring nut, bearings for rotatably mounting the threaded spindle abut against both end faces of the gear ring which are situated within the gear ring nut. Thus, the ball bearing which surrounds the gear ring is not arranged in a housing but, rather, the inner ring of the ball bearing can be slipped axially onto the gear ring nut and retained there by two locking rings which engage into outer peripheral grooves of the gear ring nut. By these measures, the overall dimensions of the worm gear and its manufacturing costs are substantially reduced.
The threaded spindle can be mounted for rotation in the gear ring nut with needle bearings. Both the needle bearings which support the gear ring nut in radial direction on the threaded spindle can be mounted directly in the gear ring nut which can comprise special axial bores starting from its end faces for receiving the needle bearings. The implementation of this embodiment is possible using three standard rolling bearings, viz., the ball bearing for the gear ring and the two needle bearings for the threaded spindle.
However, it is also possible to use sliding bearings in place of the needle bearings for rotatably mounting the threaded spindle in the gear ring nut. Such an embodiment is suitable for use with small spindle diameters under 8 mm and low spindle forces under 100 N. The gear ring nut is then shorter and cheaper. The sliding bearings can be made, for example, of a sintered bronze. The gear ring nut and the gear ring can be made of a polymeric material or of a metallic material such as a bronze.
A further embodiment of the worm gear is characterized in that the gear ring nut, the gear ring and the inner ring of the ball bearing are made together as a one-piece component which can be a hardened steel component. In this case, the gear ring nut is integral not only to the gear ring but also to the inner ring of the ball bearing so that a further reduction of manufacturing costs is achieved.
An additional pre-stress of the gear ring can be obtained by making two separate profiled sections on the bore of the gear ring and arranging them at a slight distance to each other in axial direction. This distance can correspond to the displacement path resulting from the pre-stress.
BRIEF DESCRIPTION OF THE DRAWINGS
Examples of embodiment of the invention are represented in the drawings and will be described more closely below. The drawings show:
FIG. 1, a longitudinal section through a worm gear in which the gear ring and the gear ring nut are made together as a one-piece component;
FIG. 2, a longitudinal section through a further worm gear in which the gear ring, the gear ring nut and the inner ring of the ball bearing are made together as a one-piece component.
DETAILED DESCRIPTION OF THE DRAWINGS
A worm gear of the invention shown in FIG. 1 comprises a gear ring nut 1 w
REFERENCES:
patent: 2556572 (1951-06-01), Brinkhurst
patent: 3975968 (1976-08-01), Chaffin
patent: 4743493 (1988-05-01), Sioshansi et al.
patent: 4887479 (1989-12-01), Griffey
patent: 4921403 (1990-05-01), Poucher et al.
Bucci David A.
Ina Walzlager Schaeffler OHG
Stallman Brandon C.
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