Steering Column Anti-Rotation Feature Prevents Slot Deformation
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Solution Overview
Problem
Existing steering column assemblies face challenges in adjusting rake and reach without causing permanent deformation of the support bracket's slots due to excessive clamp forces, leading to rough user experience and potential damage.
Innovation Solution
The anti-rotation feature, comprising a sintered metal block with contact portions and a spring means, is designed to deform preferentially instead of the slot walls, using materials with different coefficients of friction to absorb energy and reduce wear, ensuring smooth adjustment and preventing permanent deformation of the slot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clamp mechanism applies high clamping force to fix the steering column shroud, then the locking reliability is improved, but the slot walls of the support bracket undergo permanent deformation
Solution Approach 1:
The anti-rotation feature acts as an intermediary between the clamp mechanism and the slot walls. It includes a contact portion that preferentially deforms under clamping force, absorbing the harmful effects that would otherwise be transmitted to the slot walls. This mediator protects the slot walls from permanent deformation while still allowing the clamp to apply sufficient force for reliable locking.
Solution Approach 2:
The contact portion of the anti-rotation feature is designed with different material properties (softer material) compared to the slot walls. This parameter change in material hardness allows the contact portion to deform preferentially under load, protecting the harder slot walls from permanent deformation while maintaining effective clamping.
2Duration of action of stationary object
If the anti-rotation feature is made of hard material to prevent wear, then the durability is improved, but it causes permanent deformation of the slot walls due to excessive clamp forces
Solution Approach 1:
The contact portion uses a softer material parameter compared to the slot walls, allowing it to deform preferentially and protect the slot walls from permanent deformation. The anti-rotation feature as a whole maintains durability through its structural design and the protective function of the deformable contact portion.
Solution Approach 2:
The contact portion serves as a sacrificial intermediary that absorbs excessive clamp forces through preferential deformation. This mediator protects the slot walls from damage while the overall anti-rotation feature maintains its durability and functional life.
3Ease of operation
If the clamp mechanism is allowed to rotate freely during adjustment, then the ease of operation is improved, but unwanted rotation causes misalignment and improper clamping
Solution Approach 1:
The anti-rotation feature introduces asymmetric geometry into the otherwise symmetric clamp mechanism. The block shape with specific contact portions creates a geometric constraint that prevents rotation while maintaining ease of linear adjustment. The asymmetric shape of the anti-rotation feature fits within the slot geometry to prevent unwanted rotation.
Solution Approach 2:
The anti-rotation feature acts as an intermediary element that mediates between the need for easy operation and the need for alignment stability. It allows the clamp mechanism to move freely along the slot for adjustment while preventing rotation through its geometric constraints, thus maintaining both ease of operation and alignment stability.
4Manufacturing precision
If the contact portions are made rigid to maintain precise alignment, then the manufacturing precision is improved, but they cause permanent deformation of the slot walls under excessive clamp forces
Solution Approach 1:
The contact portion uses a softer material parameter that allows controlled deformation under excessive clamp forces. This material parameter change enables the contact portion to maintain alignment precision during normal operation while deforming preferentially to protect the slot walls from permanent deformation under abnormal high loads.
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 solution allows for smooth and precise adjustment of the steering column assembly while preventing permanent deformation of the support bracket's slots, enhancing user experience and extending the assembly's operational life by distributing forces effectively.
Implementation Method 1
the spring means and the part of the contact portion that contacts the adjacent side wall are integrally formed as two-shot moulding
Data Source
Figure 1
Figure 2
Figure 3(a)~4(b)
AI summary
An adjustable steering column assembly comprises a steering column shroud (1, 2), a support bracket (4), and a clamp mechanism. The support bracket comprises two arms (5, 6) having a portion of the column shroud located therebetween. The clamp mechanism comprises a pin (8) that passes through slots (5a) in the arms and carries a fixed cam portion (10) and moving cam portion (11), relative rotation of the fixed cam portion and moving cam portion causing the clamp mechanism to move between a locked position and an unlocked position. The fixed cam portion has an anti-rotation feature that sits at least partially within one of the slots in one of the arms and which cooperates with the side walls (16a, 16b) of the slot to substantially prevent unwanted rotation of the fixed portion of the cam mechanism. The anti-rotation feature carries at least one contact portion (15; 24a, 25a; 36, 41) that in use contacts the side walls of the slot as the steering column is adjusted and the contact portion and side walls are configured such that in use the anti-rotation feature does not cause any significant permanent deformation of the side walls due to preferential deformation of the contact portion.