A ballscrew actuator comprises a ballnut (6) having at least one first helical groove (10) formed on a radially inner surface (8) and defining an axis (X), a ballscrew (4) disposed along the axis (X) within the ballnut (6), the ballscrew (4) having at least one second helical groove (12) formed on a radially outer surface (14) and opposed to the first helical groove (10) so as to form at least one helical raceway (16) and a plurality of balls or rolling elements (18) disposed in the at least one helical raceway (12). The ballscrew (4) is movable relative to the ballnut (6) between a stowed position and a deployed position. The ballscrew (4) comprises a ballscrew bore (40) extending axially therein. A lubrication piston (42) is mounted for sliding movement within the ballscrew bore (40) and divides the ballscrew bore (40) axially into a lubricant receiving portion (44) and a pressurising portion (46). At least one lubrication passage (48) extends between the lubricant receiving portion (44) of the ballscrew bore (40) and an interface (38) between the ballscrew (4) and the ballnut (6). The actuator (2) further comprises a pump (60). The pump (60) comprises a pump chamber (62) having an outlet (64) in fluid communication with the pressurising portion (46) of the ballscrew bore (40), an air inlet passage (68) for admitting air into the pump chamber (62) and a pumping piston (66) movable in a pumping direction for pressurising air in the pump chamber (62). The pumping piston (66) is configured and arranged such that it is moved in the pumping direction as the ballscrew (4) moves axially relative to the ballnut (6) by engagement with an opposing structure of the actuator (2) during movement of the ballscrew (4) between its stowed and deployed positions. The pressurised air moves into the pressurising portion of the ballscrew bore (40) through the outlet (64) so as to move the lubrication piston (42) therein, thereby to move lubricant (20) through the lubrication passage (48).
BALLSCREW ACTUATORS
ACTIONNEURS DE VIS A BILLES
2020-11-29
Patent
Elektronische Ressource
Englisch
BALL NUT AND BALLSCREW ABSOLUTE POSITION SENSOR FOR VEHICLE STEERING SYSTEM
Europäisches Patentamt | 2023
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