Motor-Adjustable Steering Column Drive for Tolerance Compensation
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Solution Overview
Problem
Existing motor-adjustable steering columns face challenges in achieving high rigidity while minimizing tolerance requirements, leading to undesirable lateral forces and increased wear due to manufacturing tolerances and misalignment issues.
Innovation Solution
The steering column design incorporates a drive unit that is linearly displaceable and pivotable relative to the threaded spindle axis, allowing for telescopic adjustment and compensation of misalignments through a combination of sliding bearings and spring-loaded components, which enhances rigidity and reduces vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the threaded spindle is rigidly fixed between the support unit and actuating unit, then high rigidity and natural frequency are achieved, but manufacturing tolerances cause constraint conditions leading to lateral forces and increased wear
Solution Approach 1:
The drive unit is made dynamically adjustable in the transverse direction through a sliding bearing, allowing it to adapt its position to compensate for manufacturing tolerances while maintaining rigid connection during operation. This dynamic adjustment capability resolves the contradiction by enabling both high rigidity during use and tolerance compensation during positioning.
Solution Approach 2:
The transverse position of the drive unit is made variable through the sliding bearing mechanism, allowing the system to change its geometric parameters to accommodate manufacturing tolerances. This parameter change capability enables the system to maintain optimal engagement conditions between the threaded spindle and spindle nut, reducing lateral forces and wear.
2Strength
If the drive unit is fixed rigidly, then high rigidity is achieved, but tolerance deviations cause constraint conditions and reduced running smoothness
Solution Approach 1:
The sliding bearing enables the drive unit to dynamically adjust its transverse position, transforming the rigid fixed connection into a dynamically adaptable connection. This allows the system to maintain high rigidity during operation while automatically compensating for misalignments, thereby ensuring smooth running without constraint conditions.
3Manufacturing precision
If resilient clamping is used to compensate for angular errors, then tolerance compensation is achieved, but rigidity and natural frequency are reduced in an unacceptable manner
Solution Approach 1:
Instead of using resilient clamping that continuously reduces rigidity, the invention employs a sliding bearing that provides dynamic adjustability. This allows tolerance compensation only during positioning, while maintaining full rigid connection during operation, thus achieving both tolerance compensation and high rigidity without the trade-off present in resilient clamping solutions.
Solution Approach 2:
The sliding bearing acts as an intermediary element between the drive unit and the support unit/casing unit. It provides the necessary adjustability for tolerance compensation while maintaining a rigid load-bearing connection, serving as a mediator that reconciles the conflicting requirements of tolerance compensation and rigidity.
4Strength
If high tolerance requirements are imposed, then rigidity can be maintained, but manufacturing complexity and cost increase
Solution Approach 1:
The sliding bearing introduces dynamic adjustability that compensates for manufacturing tolerances, allowing the system to achieve high rigidity with relaxed tolerance requirements. The drive unit can be positioned to accommodate tolerance variations, eliminating the need for high-precision manufacturing while maintaining rigid operation.
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 achieves improved rigidity and reduced wear by allowing for precise adjustment and compensation of manufacturing tolerances, resulting in smoother operation and extended component lifespan.
Implementation Method 1
The drive unit is linearly displaceable relative to the component substantially perpendicularly transversely to the threaded spindle axis and transversely to the longitudinal axis
Implementation Method 2
a spring element which is supported on the component to which the drive unit is connected or on an abutment connected to the component and which exerts a spring force on the drive unit in the direction of its mobility according to the invention transverse to the threaded spindle axis
Data Source
Figure 1~3
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Figure 7~10
AI summary
The invention relates to a motor-adjustable steering column (1) for a motor vehicle, comprising a support unit (3), which can be attached to a vehicle body and by which an actuator unit (4) is held, in which a steering spindle (42) is rotatably mounted about a longitudinal axis (L), and having an adjusting drive (5), which is connected to the support unit (3) and to the actuator unit (4), and by which the actuating unit (4) can be adjusted relative to the support unit (3), wherein the adjusting drive (5) has a drive unit (51) and a threaded spindle (55) engaging in a spindle nut (56) and having a threaded spindle axis (R), wherein the threaded spindle (55) can be driven rotationally or translationally by the drive unit (51). In order to provide a steering column (1) having an improved adjusting drive (51), which ensures the highest possible rigidity with low tolerance requirements, the drive unit (51), according to the invention, is movably connected to a component (2, 3, 4) of the steering column (1) in a transverse direction (Q) transverse to the threaded spindle axis (R).