Machine element or mechanism – Gearing – Directly cooperating gears
Patent
1999-02-17
2000-08-15
Estremsky, Sherry L.
Machine element or mechanism
Gearing
Directly cooperating gears
F16H 1902
Patent
active
061018910
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to an apparatus for converting a rotational motion into an axial motion, including a threaded spindle, a sleeve in concentric surrounding relationship to the spindle at a spacing thereto, and a plurality of axis parallel rollers arranged in the spacing, with each of the rollers being provided with a circumferential profile and meshing with the threaded spindle.
BACKGROUND OF THE INVENTION
A conventional apparatus of this type is disclosed in European Pat. No. 0 320 621 and includes a sleeve formed as spindle nut. The rollers have not only a fine groove profiling for engagement with a fine screw thread of the threaded spindle but have in addition a coarse profiling for engagement in coarse guide grooves of the sleeve. During rotation of the threaded spindle, the rollers thus roll within the sleeve in a planetary motion on the threaded spindle as well as on the sleeve. This construction is complex and has the drawback that the sleeve as nut must be designed with a great inner profiling and each of the rollers must be designed with a fine profiling and an additional coarse profiling.
SUMMARY OF THE INVENTION
The invention is based on the object to create a threaded drive which is easier to manufacture and to assemble, while improving the attainable efficiency and reducing the manufacturing costs.
This object is attained in accordance with the invention by providing housing plates arranged in fixed rotative engagement within the sleeve for supporting each roller on both its end faces via a rolling bodies. The rolling bodies for support of the rollers may be balls disposed in bearing tracks of the housing plates. The rollers provided with the track profile thus are supported at their end faces by the sleeve via the balls. The rollers are acted upon not only by an axial force but also by a radial force. As the support is realized by two hardened housing plates, the sleeve itself may be a soft component. This design eliminates the need for an expensive roller cage and affords sufficiently great grease spaces even for a great number of rollers. Thus, the maintenance periods can be extended. A particular advantage resides in the capability to make the rollers geometrically completely identical and to mount them in random sequence. The sleeve and both housing plates can be made in a particularly economical fashion through deep-drawing, punching and embossing.
On their sides distant to the rolling bodies, the housing plates may have flat ring surfaces which extend at a right angle to the longitudinal axis of the threaded spindle. The flat ring surfaces of the housing plates may be axially supported by the end face regions of the sleeve. The necessary pretension for the axial bearings of the rollers may be realized by arranging a disk spring between a sleeve collar on one end face and the adjoining housing plate.
The track depth of the bearing tracks for the balls of the rollers arranged sequentially in circumferential direction of the threaded spindle may change on the housing plates in correspondence to the pitch of the thread of the threaded spindle. Thus, both housing plates which are secured against rotation have ball bearing races which are embossed at different depths.
Unlike conventional roller-type threaded drives, the construction according to the invention has profiled rollers which are fixedly supported in the sleeve, i.e. the rollers do not orbit around the spindle during rotation of the threaded spindle and of the rollers in rolling contact therewith. The thread pitch of this threaded drive depends only on the threaded spindle.
BRIEF DESCRIPTION OF THE DRAWINGS
An exemplified embodiment of the invention will now be described in more detail with reference to the drawing, in which:
FIG. 1 is a longitudinal section through a roller-type threaded drive;
FIG. 2 the cutaway view Z of FIG. 1 of the engagement zone of a threaded spindle and a profiled roller, on an enlarged scale;
FIG. 3 a cross-section through the roller-type threaded drive, taken along the
REFERENCES:
patent: 511679 (1893-12-01), Buckley
patent: 2488256 (1949-11-01), Anderson
patent: 3744332 (1973-07-01), Nilsson
patent: 4074586 (1978-02-01), Nussbaum
patent: 4884466 (1989-12-01), Duruisseau
Estremsky Sherry L.
Feiereisen Henry M.
Ina Walzlager Schaeffler OHG
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