Adjustment drive for a steering column, motor-adjustable steering column for a motor vehicle, and method for adjusting a bearing assembly of an adjustment drive

An adjustment drive for a steering column that is adjustable by motor for a motor vehicle, comprising:

• a spindle nut,
• a threaded spindle with an axis, said threaded spindle engaging in the spindle nut,
• a drive unit, and
• a gear wheel connected to the spindle nut or the threaded spindle for rotation therewith, the gear wheel configured to be rotated about the axis by the drive unit and which is rotatably mounted about the axis in a bearing housing in a bearing arrangement between two outer bearing rings that are axially supported at the bearing housing,
• wherein the outer bearing rings each have, on their sides facing one another, a circumferential outer bearing face that is coaxial to the axis, each said outer bearing face positioned opposite a bearing face formed on the end side at the gear wheel, wherein at least one of the outer bearing rings is supported in an axially resilient manner at the bearing housing by way of an elastic preloading element configured to exert a preloading force that axially biases the two outer bearing rings against one another.

A steering column that is adjustable by motor for a motor vehicle, comprising

• a carrying unit configured to attach to a vehicle body,
• an actuating unit held by the carrying unit,
• a steering spindle rotatably mounted about a longitudinal axis in the carrying unit, and
• an adjustment drive connected to the carrying unit and to the actuating unit, via which the actuating unit is adjustable relative to the carrying unit,
• wherein the adjustment drive comprises:
• a spindle nut,
• a threaded spindle with an axis, said threaded spindle engaging in the spindle nut,
• a drive unit, and
• a gear wheel connected to the spindle nut or the threaded spindle for rotation therewith, the gear wheel configured to be rotated about the axis by the drive unit and which is rotatably mounted about the axis in a bearing housing in a bearing arrangement between two outer bearing rings that are axially supported at the bearing housing,
• wherein the outer bearing rings each have, on their sides facing one another, a circumferential outer bearing face that is coaxial to the axis, each said outer bearing face positioned opposite a bearing face formed on the end side at the gear wheel, wherein at least one of the outer bearing rings is supported in an axially resilient manner at the bearing housing by way of an elastic preloading element configured to exert a preloading force that axially biases the two outer bearing rings against one another.

A method for setting a bearing arrangement of an adjustment drive for a steering column that is adjustable by motor for a motor vehicle, comprising a threaded spindle with an axis, said threaded spindle engaging in a spindle nut, and a gear wheel which is connected to the spindle nut or the threaded spindle for rotation therewith and which is rotatably mounted about the axis in a bearing housing in a bearing arrangement between two outer bearing rings that are axially supported at the bearing housing, wherein an outer bearing ring is supported in an axially resilient manner at the bearing housing by way of an elastic preloading element, the method comprising:

• applying an axial preloading force to the preloading element,
• applying a load moment to the gear wheel and measuring the load moment,
• measuring a bearing state variable that is correlated with the load moment,
• comparing the measured bearing state variable with a predetermined state target value,
• when the measured bearing state variable deviates from the state target value:
• modifying the axial preloading force, and
• when the measured bearing state variable attains the state target value:
• affixing the preloading element in an axial preloading position at the bearing housing and completing the setting process.

A method for setting a bearing arrangement of an adjustment drive for a steering column that is adjustable by motor for a motor vehicle, comprising a threaded spindle with an axis, said threaded spindle engaging in a spindle nut, and a gear wheel which is connected to the spindle nut or the threaded spindle for rotation therewith and which is rotatably mounted about the axis in a bearing housing in a bearing arrangement between two outer bearing rings that are axially supported at the bearing housing, wherein an outer bearing ring is supported in an axially resilient manner at the bearing housing by way of an elastic preloading element, comprising the steps of:

• applying an axial preloading force to the preloading element,
• measuring the axial preloading force,
• comparing the measured preloading force with a predetermined target preloading force,
• when the measured preloading force deviates from the predetermined target preloading force:
• modifying the axial preloading force, and
• when the measured preloading force attains the predetermined target preloading force:
• affixing the preloading element in an axial preloading position at the bearing housing and completing the setting process.