Patent ID: 7526978
Filing Date: 2009-05-05
Classification: F16C,F16D

Abstract:
1. A device for coupling an inner shaft and a concentrically arranged tubular outer shaft sliding one within the other in the direction of a common axis, said inner and outer shafts having adjacent peripheral surface containing axially extending concave portion, said coupling device including a plurality of balls, each of said balls being disposed between a concave portion of the inner shaft and a concave portion of the outer shaft and moving on two rolling tracks disposed one on each side of a median plane passing through the common axis and through centers of said balls; each of the two rolling tracks cooperating with the concave portion of one of the shafts and pivots about an articulation axis parallel to the common axis, said articulation axis being situated between a sliding face and the concave portion of one of said inner shaft and outer shaft, so that each rolling track pivots at a junction of the sliding face and the concave portion; each of the two rolling tracks being pushed against each of said balls by a spring member disposed in and bearing on said concave portion of the inner shaft; each of said balls rolling directly against the concave portion of the outer shaft, wherein the balls are arranged in a plurality of axial rows: each row of balls being disposed in a concave portion of the outer shaft in the form of an axial groove whose section includes two concave faces inclined to each other which come into contact with the balls of said each row: each row of balls being disposed in a concave portion of the inner shaft in the form of an axial groove whose section includes a bottom and two flanks, the bottom being substantially perpendicular to the median plane passing through the common axis and through the axis of the centers of the balls of said each row; two rolling tracks for each row of balls being disposed one on each side of the median plane and cooperate with the concave portion in the form of the axial groove of the inner shaft and each rolling track takes the form of an axial bar whose section has: a bearing portion with a face adapted to come into contact with the balls of said each row: a pivot portion in the form of a fork with a concave face that cooperates with a conjugate convex shape of a junction face disposed between the face of the inner shaft and the corresponding flank of the axial groove, the concave face and the junction face having a substantially cylindrical shape whose axis is the articulation axis; and each of the two rolling tracks is pushed by a spring member that bears on said bottom of the axial groove of the inner shaft, so that: at rest, when there is no transmission of torque, and when active, when there is transmission of torque, each of said balls is always in contact on each side of the median plane, via one bearing area, with the corresponding rolling track disposed in one of the two shafts, and through another bearing area with the concave portion of the other shaft, and the center of each of said balls, a &enter of the bearing area with the rolling track, and a corresponding center of the articulation axis of said rolling track are always aligned.