Electric power steering system with a ball-screw assembly
AssigneeZF Friedrichshafen AG
InventorsBenjamin Warren Schoon, Caleb Seth Crum
Life of this patent
Estimating the term…
Abstract
An electric power steering assembly includes an electric motor, a gearset, and a ball-screw assembly. The gearset couples the electric motor and a ball nut of the ball-screw assembly such that the electric motor is operable to rotate the ball nut relative to the ball shaft. A plurality of bearings are circulatable through a helical track, which is defined between the ball nut and a ball shaft of the ball-screw assembly, when the ball nut rotates relative to the ball shaft in order to translate the ball shaft relative to the ball nut.
Claims19
An electric power steering assembly, comprising:
- a ball-screw assembly comprising
- a ball nut and a ball shaft collectively defining a helical track, the ball nut rotatable relative to the ball shaft, and
- a plurality of bearings circulatable through the helical track when the ball nut rotates relative to the ball shaft in order to translate the ball shaft relative to the ball nut;
- an electric motor;
- a gearset coupling the electric motor and the ball nut such that the electric motor is operable to rotate the ball nut relative to the ball shaft, the gearset comprising a first gearwheel, a second gearwheel, and a third gearwheel, the first gearwheel coupled to a rotor of the electric motor, the third gearwheel meshed with a gear toothing of the ball nut, the second gearwheel disposed between the first and third gearwheels in a power flow path between the first and third gearwheels;
- and
- a bevel gearbox, an input of the bevel gearbox connectable to a steering wheel column, an output of the bevel gearbox connected to the second gearwheel of the gearset,
- wherein the output of the bevel gearbox is connected to the second gearwheel of the gearset such that rotation of output of the bevel gearbox is transferred to gearset via the second gearwheel.
An electric power steering assembly, comprising:
- a ball-screw assembly comprising
- a ball nut and a ball shaft collectively defining a helical track, the ball nut rotatable relative to the ball shaft, and
- a plurality of bearings circulatable through the helical track when the ball nut rotates relative to the ball shaft in order to translate the ball shaft relative to the ball nut;
- an electric motor;
- a gearset coupling the electric motor and the ball nut such that the electric motor is operable to rotate the ball nut relative to the ball shaft, the gearset comprising a first gearwheel, a second gearwheel, and a third gearwheel, the first gearwheel coupled to a rotor of the electric motor, the third gearwheel meshed with a gear toothing of the ball nut, the second gearwheel meshed with the first and third gearwheels;
- a planetary gear set, one of a sun gear, a carrier, and a ring gear of the planetary gear set connected to the rotor of the electric motor, another one of the sun gear, the carrier, and the ring gear of the planetary gear set connected to the first gearwheel of the gearset;
- and
- a bevel gearbox, an input of the bevel gearbox connectable to a steering wheel column, an output of the bevel gearbox connected to the second gearwheel of the gearset,
- wherein the output of the bevel gearbox is connected to the second gearwheel of the gearset such that rotation of output of the bevel gearbox is transferred to gearset via the second gearwheel.
Dependencies are inferred from the claim text.