Steering Column Coupling Rod Deflection Limiting Guide
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Solution Overview
Problem
Existing motor-adjustable steering columns face safety issues during crashes due to the risk of the coupling rod deflecting and bending under high axial compressive forces, which can lead to steering column malfunction, especially with longer coupling rods that increase the risk of buckling stress and transverse forces.
Innovation Solution
A deflection limiting device with a guide opening that surrounds the coupling rod, providing a loose positive connection to prevent lateral deflection and support the coupling rod, ensuring it can move axially with minimal friction, thereby limiting deflection and preventing bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the coupling rod is made longer to increase the adjustment range of the steering column, then the adjustment range is improved, but the risk of buckling stress and transverse forces increases
Solution Approach 1:
The patent introduces guide openings in the casing tubes as intermediary structures that constrain the coupling rod. These guide openings act as mediators between the coupling rod and the casing, providing lateral support and preventing buckling while allowing the coupling rod to maintain its necessary length for adjustment range.
2Adaptability or versatility
If the coupling rod is made longer to increase the adjustment range, then the adjustment range is improved, but the coupling rod may deflect sideways and become bent under axial compressive force
Solution Approach 1:
The guide openings serve as intermediary constraint structures that prevent lateral deflection of the coupling rod. By introducing these guide structures, the patent maintains the coupling rod's length for adjustment purposes while preventing it from bending under compressive loads.
Solution Approach 2:
The patent adds a dimensional constraint by introducing guide openings that restrict movement in the lateral dimension while allowing axial movement. This dimensional control prevents deflection perpendicular to the coupling axis while maintaining the necessary adjustment range along the axial direction.
3Reliability
If a deflection limiting device is added to prevent coupling rod buckling, then the safety is improved, but the device complexity increases
Solution Approach 1:
The guide openings serve multiple functions: they constrain the coupling rod laterally to prevent buckling, guide the coupling rod during adjustment movements, and provide structural integration with the casing tubes. By making the guide openings multi-functional, the patent improves safety without adding separate dedicated components.
Solution Approach 2:
The deflection limiting function is merged with the existing casing tube structure by forming guide openings directly in the casing tubes. This integration combines the structural support function of the casing with the deflection limiting function, eliminating the need for separate deflection limiting components.
Data Source
Figure 1
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AI summary
The present invention relates to a motor-adjustable steering column (1) for a motor vehicle, comprising a mounting unit (5), which can be connected to a vehicle body and retains an actuating unit (2), which comprises a steering spindle (4) mounted for rotation about a longitudinal axis (L) in a sleeve unit (3), wherein the sleeve unit (3) has at least two steering column tubes (31, 32, 33) which are adjustable relative to one another and are connected to an adjustment drive (6), which has a coupling rod (62) extending along the coupling axis (S) thereof, which coupling rod engages on steering column tubes (31, 32, 33) that are adjustable relative to one another, is operatively connected to a motorized drive unit (63) and can be adjusted by the drive unit (63) relative to at least one of the steering column tubes (31, 32, 33). According to the invention, in order to allow increased permissible loads and vehicle safety, a deflection limiting device (7) is arranged between the sleeve unit (3) and the coupling rod (62), which limits deflection of the coupling rod (63) transverse to the coupling axis (S).