Patent ID: 8834311
Filing Date: 2014-09-16
Classification: F16H,H02K

Abstract:
1. A drive system with a central longitudinal axis, comprising: a brushless DC servomotor having a stator with a stator housing and stator motor windings and a rotor disposed radially interior of the stator motor windings, the rotor having a hollow cylindrical base and a plurality of magnets fixed to a radially exterior surface of the base, the hollow cylindrical base defining a central void space, the stator and rotor being coaxial with the central longitudinal axis; a first rotor flange coaxially fixed to one end of the rotor, the first rotor flange defining a central opening coaxial with the central longitudinal axis, the first rotor flange including a first portion of a two-portion torque transfer mechanism; an input shaft disposed coaxially with the brushless DC servomotor, the input shaft including a second portion of the two-portion torque transfer mechanism, the second portion being in engagement with the first portion on the first rotor flange; a first stator flange fixed to one end of the stator housing and coaxial with the central longitudinal axis, the first rotor flange being concentrically disposed within the first stator flange; a roller bearing interposed between the first stator flange and the first rotor flange to support the one end of the rotor; a second rotor flange coaxially fixed to another end of the rotor, the second rotor flange defining a central opening coaxial with the central longitudinal axis; a second stator flange fixed to another end of the stator housing and coaxial with the central longitudinal axis, the second rotor flange being concentrically disposed within the second stator flange; a second roller bearing disposed between the second stator flange and the second rotor flange to support the other end of the rotor; a planetary gear assembly fixed to the second stator flange and concentric with the central longitudinal axis, the planetary gear assembly including a housing with a ring gear on an interior of the housing, the housing being disposed in the central void space of the rotor, the input shaft extending into the housing and being rotatable with respect to the housing, the planetary gear assembly further including a sun gear fixed to and rotatable with the input shaft and a plurality of planet gears that simultaneously mesh with both the ring gear and the sun gear, the planetary gear assembly further including a carrier rotatably fixed to each of the planet gears; and an output shaft rotatably fixed to the carrier and coaxial with the central longitudinal axis, the output shaft extending through the planetary gear housing; wherein the drive system has an overall length L and an external diameter d and L/d is about one or less than one.