PLANETARY ROLLER-SCREW DRIVE Russian patent published in 2003 - IPC

FIELD: mechanical engineering. SUBSTANCE: proposed planetary roller-screw drive consists of control system with unit to supply and control operation of piezoceramic rings, base with straight and return travel limiters and support members in which screw with motor and build up nut. Nut consists of body 13 with covers 14. Piezoceramic ring 16, half-nut 17 and ring 18 with internal gear rim 19 are installed between each base end face surface of ring step 15 and cover 14. Threaded rollers 22 engage with screw 6 and half nuts 17 by turns of thread. Threaded rollers are brought into meshing by their gear rims 24 with rims 19 of rings 18 for synchronization. With planetary roller-screw drive operating, voltage is applied to piezoceramic rings which expand and shift half-nuts to take up clearance between turns of half-nuts and threaded rollers and turns of threaded rollers and screw, thus building preliminary compressive force. Nut shifts slave mechanism to required point in space definitely at high rigidity. At return travel, piezoceramic rings contract and assume their initial shape and size. EFFECT: increased efficiency and longevity of drive. 2 dwg