Machine element or mechanism – Mechanical movements – Reciprocating or oscillating to or from alternating rotary
Patent
1998-05-13
2000-02-22
Herrmann, Allan D.
Machine element or mechanism
Mechanical movements
Reciprocating or oscillating to or from alternating rotary
74411, 744248C, 74459, F16H 2522
Patent
active
060266961
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
The present application claims the priority of German Patent Application 195 42 453, filed on Nov. 14, 1995, the disclosure of which is herewith also explicitly made the subject matter of the present application.
TECHNICAL FIELD
The invention concerns a device for converting a rotary motion into an axial motion, the device including: an outer tube with internal contours; an inner shaft having a head including external contours, the inner shaft having a central axis; an inner chamber formed between the tube and the shaft; and several roller elements arranged in the inner chamber and around the head of the shaft, each roller element including at least one contour in active engagement with the internal contour of the tube and the external contour of the head, wherein the position of the head is axially adjustable essentially by rotation of the head relative to the roller elements.
PRIOR ART
Such a device is, for example, known from CH 290 685 within the meaning of a planetary-rolling-threaded-spindle drive. Planets, which are substantially axially fixed and into which a threaded spindle lying inside plunges, act together with a tubular nut in a rolling manner relative to the nut. This device for converting a rotary motion into an axial motion works very effectively and is long lasting due to the fact that the planets roll off in the manner of roller elements, and since no threads or contours are arranged on the outside. Dirt accumulation can be avoided in this way, so that the working life of the whole drive is increased. The use of a tube, compared with a solid spindle, reduces the masses to be moved. The motion essentially is effected inside the tube, so that the tube itself constitutes a protection for the parts moved relative to each other. However, this protective function is lessened by the fact that the shaft bearing the threaded spindle rotates relative to the tubular nut in the sealing region, so that not only the sealing is subject to an additional wear, but also dirt particles cannot be reliably kept away from the inner chamber over the long term (See DE AS 1 043 743).
DE-A 44 07 537 discloses the use of roller elements with different contours, in which each roller element meshes into the interior contour of the tubular nut or into the exterior contour of the spindle.
From AT-E 0 843 it is known to position the roller elements in an axial direction counter to a force of elastic elements to safeguard against shock. However, it is not intended to uncouple the drive from the force flow by use of these elastic elements.
SUMMARY OF THE INVENTION
Based on this state of the art, it is an object of the invention to provide a device of the type first mentioned above for converting a rotary motion into an axial so a protection against exterior influences is afforded in an easy manner.
The above and other objects are accomplished according to the invention by the provision of a device for converting a rotary motion into an axial motion, comprising: an outer tube with internal contours; an inner shaft having a head including external contours, the inner shaft having a central axis; an inner chamber formed between the tube and the shaft; several roller elements arranged in the inner chamber and around the head of the shaft, each roller element including at least one contour in active engagement with at least one of the internal contour of the tube and the external contour of the head, wherein the head and roller elements are axially displaceable relative to the tube essentially by rotation of the head relative to the roller elements during which the head remains essentially axially non-displaceable relative to the roller elements; a tubular element arranged coaxially with respect to the central axis of the shaft and being axially translational relative to the outer tube; and an elastic mechanism presenting a preset axial force biasing the shaft in a direction of the central axis relative to the tubular element such that when the device is actuated for rotating t
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Herrmann Allan D.
Kinberg Robert
Spencer George H.
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