Rotary shaft control apparatus
OwnerBernard Stiffinventor
Life of this patent
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Abstract
Apparatus for controlling a rotary shaft relative to a reference includes a strain wave drive having a specially shaped deformable ring gear for minimum stress. The wave generator part of the drive is normally caused to rotate with the input and output shafts connected to the drive's ring gears so that the two shafts are effectively keyed together. A tractive-type clutch assembly permits the wave generator to be rotated in one direction or the other relative to the deformable gear shaft so that the phase angle of the two shafts can be adjusted at a slow rate of speed dependent on the gear ratio of the drive. Also a tractive-type planetary assembly may be coupled between the clutch assembly and the wave generator so that the phase change may be accomplished at a plurality of speeds.
Claims8
In a strain wave drive apparatus of the type including a rigid ring gear, a deformable ring gear juxtaposed with the rigid gear and a wave generator engaging the deformable gear and deflecting at least a portion of it into engagement with the rigid gear for use particularly in rotary shaft control apparatus the improvement wherein the deformable gear is formed as an annular noncylindrical body of revolution, one end portion of the body in toothed engagement with the rigid gear being generally conical with a first selected maximum diameter, and tapering to a second diameter less than said first diameter, said second diameter defining a first plane through the gear, the portion of the gear beyond said first plane flaring outwardly with a smooth shape transition to a third diameter greater than the second diameter, said third diameter defining a second plane through the gear where radial and axial gear motions are minimal when the wave generator is rotated relative to the deformable gear.
In a strain wave drive apparatus of the type including a rigid toothed ring gear, a deformable toothed ring gear juxtaposed with the rigid gear and a rotary strain wave generator engaging the deformable gear and deflecting at least the toothed portion of it into engagement with the rigid gear so that when the wave generator is rotated relative to the deformable gear, that gear tends to rotate relative to the rigid gear, the improvement wherein the deformable gear is formed as an annular noncylindrical body of revolution, said gear having a frustoconical axial segment which carries the teeth that mesh with the rigid gear, a cylindrical axial segment for mounting the gear to a rotary member and a third axial segment connecting the frustoconical and cylindrical segments which forms a smooth constricted transition therebetween so as to permit the first segment to angulate about the polar axis of the gear.
Dependencies are inferred from the claim text.