Machine element or mechanism – Mechanical movements – Reciprocating or oscillating to or from alternating rotary
Patent
1997-12-03
1999-09-28
Graysay, Tamara L.
Machine element or mechanism
Mechanical movements
Reciprocating or oscillating to or from alternating rotary
74459, 744248R, F16H 2524, F16H 2702
Patent
active
059569972
DESCRIPTION:
BRIEF SUMMARY
FIELD 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 on at least one needle roller bearing in a gear ring nut which functions as a housing, a profiled gear ring engaging a thread of the spindle at one peripheral point for axially displacing the gear ring nut, the gear ring which surrounds the threaded spindle being arranged eccentric to the spindle axis while being surrounded by a radial rolling bearing on which the gear ring is rotatably mounted in the housing.
BACKGROUND OF THE INVENTION
A worm gear of this type is known from EP-PS 0 122 596 and comprises two gear rings arranged with ball bearings in a housing, the outer rings of the ball bearings being arranged in special rolling bearing receiving elements which surround the threaded spindle. The needle roller bearings which serve as radial supports for the gear ring nut likewise have separate outer or gear rings. This makes the structure 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 the housing is composed of rotationally symmetrical sheet metal parts made by chipless deep drawing, the inner surfaces of which sheet metal parts directly comprise the outer rolling element raceways for the bearings. The housing can therefore be assembled from hardened, drawn parts which at the same time serve as bearing raceways. This results in a compact structure of the worm gear which thus comprises only a few individual parts.
At its end remote from the gear ring, the housing can be configured in the direction of the spindle axis as a pot-shaped piston. Thus, it is closed at one end and the threaded spindle is protected from damage and pollution. Besides this, lubricant cannot be lost and thus remains inside the gear ring nut.
The housing comprises an outer bearing ring for the needle roller bearing of the threaded spindle and, connected thereto, an outer bearing ring for the radial rolling bearing of the gear ring. The bearing ring for the needle roller bearing and the bearing ring for the radial rolling bearing can be made together in one piece as a sheet metal part so that a particularly simple embodiment results.
The radial rolling bearing for the gear ring can be configured as a ball bearing transmitting both axial and radial forces. It is, however, also possible to configure the radial rolling bearing for the gear ring as a needle roller bearing in which case the gear ring is rotatably mounted in the housing on two additional axial needle roller bearings. Such a construction offers the advantage of higher axial rigidity and higher basic load ratings than obtained by using a ball bearing because needle roller bearings usually have higher load ratings and stiffness. Besides this, the design space requirement is smaller in the case of needle roller bearings.
The raceways for the rolling bearings of the gear ring are constituted directly by the surfaces of the gear ring. The gear ring can be retained axially in the housing by an inwardly bent edge of the housing. It is possible to arrange two needle roller bearings for the threaded spindle in the housing, one of said two needle roller bearings being arranged on each side of the gear ring. In this case, the housing can comprise an additional bearing ring for the second needle roller bearing of the threaded spindle, said additional bearing ring being axially retained on the bent-over edge of the housing by an adjoining flange.
BRIEF DESCRIPTION OF THE DRAWINGS
Examples of embodiment of the invention are represented in the drawings and will be described more closely below. In the drawings
FIG. 1 is a longitudinal section through a worm gear whose gear ring is mounted in the housing on two axial needle roller bearings and one radial needle roller bearing;
FIG. 2 is a longitudinal section through a worm gear comprising
REFERENCES:
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Oetjen Jurgen
Zernickel Alexander
Belles Debra A.
Feiereisen Henry M.
Graysay Tamara L.
Ina Walzlager Schaeffler OHG
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