Motor-Adjustable Steering Column Drive With Transverse Compliance
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Solution Overview
Problem
Existing motor-adjustable steering columns face challenges in achieving maximum rigidity while accommodating manufacturing tolerances, leading to constrained states that result in noise and increased wear due to transverse forces and vibrations.
Innovation Solution
The steering column design incorporates a drive unit that is movable transversely to the threaded spindle axis, allowing for linear displacement and swiveling about a transverse axis, which compensates for deviations caused by tolerances and constraining forces, thereby enhancing rigidity and reducing vibrations through the use of spring-loaded components and sliding bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the actuator unit is force-guided by the support unit with little play to achieve maximum rigidity, then rigidity and eigenfrequency are improved, but manufacturing tolerances cannot be balanced and constrained states occur leading to noise and wear
Solution Approach 1:
The drive unit is made movable relative to the actuator unit through a guiding device with sliding bearings, allowing dynamic adjustment to compensate for manufacturing tolerances while maintaining rigidity. The system transitions from a static force-guided connection to a dynamic adjustable connection that adapts to tolerance variations.
Solution Approach 2:
The connection between the drive unit and actuator unit is segmented into movable and fixed parts. The drive unit can move independently within the guiding device, separating the function of force transmission (maintained by the support unit) from the function of tolerance compensation (performed by the movable drive unit).
2Device complexity
If the drive unit is fixed to maintain structural simplicity, then device complexity is reduced, but manufacturing tolerances cause constrained states and increased wear
Solution Approach 1:
The guiding device acts as an intermediary between the drive unit and actuator unit. It provides a controlled movement path with sliding bearings that allows the drive unit to adjust for tolerances without requiring complete redesign of the connection system, thus maintaining relative structural simplicity while improving reliability.
3Manufacturing precision
If spring-loaded clamping is used to balance manufacturing tolerances, then tolerance compensation is improved, but rigidity and eigenfrequency of the telescopic assembly are decreased
Solution Approach 1:
Instead of using spring-loaded clamping that continuously applies force and reduces rigidity, the invention uses a guiding device that allows controlled movement of the drive unit. This dynamic adjustment compensates for tolerances only when needed, maintaining maximum rigidity during normal operation.
Solution Approach 2:
The solution moves from a one-dimensional spring compression approach to a two-dimensional approach combining rigid support with controlled linear movement along the guiding device axis. This allows tolerance compensation in the movement direction while maintaining rigidity in all other directions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design increases the quiet running and reduces wear by allowing the drive unit to adjust relative to the actuator and support units, maintaining high rigidity and eigenfrequency while balancing manufacturing tolerances, thus avoiding constrained states and noise production.
Implementation Method 1
a spring element (81, 82) which exerts a spring force (F) on the drive unit (51) in the transverse direction (Q)
Implementation Method 2
sliding bearings
Data Source
AI summary
A motor-adjustable steering column for a motor vehicle, includes a support unit, which can be mounted on a vehicle body, and by which an actuator unit is held, in which a steering spindle is rotatably mounted about a longitudinal axis. An adjusting drive is connected to the support unit and to the actuator unit, and by which the actuator unit can be adjusted relative to the support unit. The adjusting drive includes a drive unit and a threaded spindle engaging in a spindle nut with a threaded spindle axis, wherein the threaded spindle can be driven in rotation or in translation by the drive unit. The drive unit is connected to a component of the steering column such that it is movable in a transverse direction transversely to the threaded spindle axis.