Flexible pivot with internal pivoting axis

Details Flexible pivot with internal pivoting axis Flexible pivot with internal pivoting axis

1999-07-16

2001-07-31

Oberleitner, Robert J. (Department: 3613)

Spring devices

Bendable along flat surface

Ring or annular spider

C267S160000, C464S091000, C248S567000

Reexamination Certificate

active

06267363

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flexible pivot with internal pivoting axis. It also relates to an assembly of a plurality of such pivots.
The term “flexible pivot with internal pivoting axis” pertains to a centered pivot corresponding to a kinematic pivot with a real pivoting axis that is located within the structure, as opposed to off-centered pivots corresponding to a kinematic pivot with a virtual pivoting axis located outside the structure, possibly at infinity, the motion then amounting to the motion of translation.
2. Description of the Prior Art
In the prior art, there is a known flexible pivot with internal pivoting axis, known as a cross-band pivot because the pivoting motion is obtained by flexible band-shaped elements positioned in orthogonal planes. However, this type of centered pivot is asymmetrical, which complicates its manufacture and raises problems of internal hyperstaticity. Another drawback lies in the structure of the added-on bands.
A second known centered pivot consists of a plurality of bands extending radially from the pivoting axis, a first set of bands being fixed while a second set is related to the object which is mobile in pivoting. Although it is monolithic and seamless, this other type of known centered pivot however has a structure that remains asymmetrical with all the negative consequences of such a structure on the load and the space requirement. Furthermore, the center of the pivot is completely occupied by material, and this may be a drawback, for example for the passage of an optical beam.
SUMMARY OF THE INVENTION
Thus, the technical problem to be resolved by the present invention is to propose a monolithic flexible pivot with internal pivoting axis that is seamless and without internal joints, leaving free the central passage and having maximum stability under load stresses for minimum space requirement.
The solution to the technical problem raised, according to the present invention, lies in the fact that the pivot has two stages that are symmetrical with respect to a median plane perpendicular to the pivoting axis and separated by an external circular recess containing the median plane, each stage comprising an annular interface connected by a plurality of radial, flexible guiding arms to a common intermediate cylinder having an axis that is the same as the internal pivoting axis.
Thus, the structure of the flexible pivot according to the invention is monolithic, symmetrical by its principle, stable and compact. Furthermore, the central part of the pivot, constituted by the interior of the intermediate cylinder, is unoccupied. In particular, it allows the passage of an optical beam in an application of the flexible pivot of the invention to a telescope.
The rotational travel of the flexible pivot that is an object of the invention is limited to a few degrees. It may be observed that, advantageously, the off-centering remains zero during rotation.
In order to increase the rotational travel of the pivot, it is provided according to the invention that the intermediate cylinder will be radially flexible. This arrangement indeed makes it possible to keep the distance between the internal pivoting axis and the annular interface constant over a greater range of travel, through the radial deformation of the intermediate cylinder.
According to one particular embodiment of the invention, the radial flexibility desired is obtained by the fact that the intermediate cylinder has annular undulations.
It is also possible to increase the rotational travel of the flexible pivot according to the invention by assembling several pivots so as to add up the intermediate distances of travel of each pivot. To this end, the invention proposes two types of assembling.
According to a first embodiment, the assembling is obtained by the stacking of flexible pivots, an annular interface of a pivot being fixed to the contiguous annular interface of a neighboring pivot.
According to a second embodiment, the assembling is obtained by the monolithic stacking of the flexible pivot, an annular interface of a pivot forming one piece with a contiguous annular interface of a neighboring pivot while the guiding arms and the intermediate cylinder of a pivot are separated from the contiguous guiding arm and intermediate cylinder of a neighboring pivot by an internal circular slot.


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