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1. (WO2016181341) LINEAR DRIVE MECHANISM OF THE SCREW AND NUT TYPE WITH PERFECT ROLLING CONTACT

Pub. No.:    WO/2016/181341    International Application No.:    PCT/IB2016/052739
Publication Date: Fri Nov 18 00:59:59 CET 2016 International Filing Date: Fri May 13 01:59:59 CEST 2016
IPC: F16H 25/22
Applicants: FONDAZIONE ISTITUTO ITALIANO DI TECNOLOGIA
Inventors: FEATHERSTONE, Roy
Title: LINEAR DRIVE MECHANISM OF THE SCREW AND NUT TYPE WITH PERFECT ROLLING CONTACT
Abstract:
The mechanism (10) comprises a threaded shaft (12) extending along a longitudinal axis (z); a nut (14) arranged coaxially with the threaded shaft (12); a plurality of a plurality of rolling bearings (18) interposed between the threaded shaft (12) and the nut (14), each of the bearings (18) comprising an outer race (22) fixed to the nut (14), an inner race (20) which is arranged coaxially with the outer race (22) and is rotatable relative to the outer race (22) about an axis of rotation (z'), and a plurality of rolling members (24) interposed between the outer race (22) and the inner race (20); and a corresponding plurality of rings (16), each of which is fixed to the inner race (20) of a respective bearing (18) so as to rotate therewith about the same axis of rotation (z'), and is interposed between the inner race (20) of the bearing (18) and the threaded shaft (12) in such a manner that an inner surface (16a) of the ring is in contact with a screw thread (12a) of the threaded shaft (12). The rings (16) and the bearings (18) are arranged in such a manner that their respective axes of rotation (z') are both inclined by a first angle (α) and positioned at a first distance (α) with respect to the longitudinal axis (z) of the threaded shaft (12), said first angle (α) and said first distance (α) being the same for all the rings (16). The shape of the screw thread (12a) of the threaded shaft (12) and the shape of the inner surface (16a) of each ring (16) are configured in such a manner that each ring (16) is in perfect rolling contact with the threaded shaft (12) along a respective contact line (v) that is fixed relative to the nut (14) and is both inclined by a second angle (β) and positioned at a second distance (b) with respect to the longitudinal axis (z) of the threaded shaft (12).