Steering Column Jacket Stiffening Sleeve for Natural Frequency
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Solution Overview
Problem
Steering column jackets face a challenge in increasing their natural frequency without significantly increasing mass, as thicker materials lead to higher natural frequencies but also add unnecessary weight.
Innovation Solution
A stiffening sleeve is introduced, with a radially outer surface fixed to the inner surface of the upper jacket, providing localized stiffness to the steering column while maintaining a reduced mass by being press-fitted within the jacket, thereby enhancing the natural frequency without thickening the entire jacket.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the material thickness of the upper jacket is increased, then the vertical and lateral natural frequency increases, but the upper jacket mass increases
Solution Approach 1:
The patent applies local quality by inserting a stiffening sleeve only in specific regions where additional stiffness is needed, rather than uniformly thickening the entire upper jacket. This localized reinforcement increases the natural frequency while minimizing the added mass, as the stiffening effect is concentrated where most beneficial.
Solution Approach 2:
The patent uses composite materials by combining the upper jacket material with a stiffening sleeve material having different mechanical properties. The stiffening sleeve is made of a material with higher stiffness-to-weight ratio, creating a composite structure that achieves improved natural frequency with minimal mass increase.
2Strength
If the material thickness of the upper jacket is increased, then the stiffness increases, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent applies segmentation by dividing the stiffening function into a separate component (the stiffening sleeve) rather than incorporating it into the main upper jacket structure. This allows the stiffening functionality to be added as a modular element, simplifying manufacturing and assembly while achieving the required stiffness.
Solution Approach 2:
The patent uses the nested doll principle by placing the stiffening sleeve inside the upper jacket structure. The sleeve is inserted into the hollow interior of the upper jacket, creating a nested configuration where the inner sleeve reinforces the outer jacket without requiring modification of the jacket's external dimensions or complex multi-layer construction.
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
The solution effectively increases the natural frequency of the steering column by adding stiffness without substantially increasing the mass, meeting the requirements of OEMs for both natural frequency and mass targets.
Implementation Method 1
A stiffening sleeve is introduced, with a radially outer surface fixed to the inner surface of the upper jacket, providing localized stiffness to the steering column while maintaining a reduced mass
Implementation Method 2
The radially outer surface of the stiffening sleeve is fixed to the inner surface of the jacket
Data Source
AI summary
A steering column assembly includes a jacket having a first end, a second end, a jacket length, and an inner surface defining a bore. The steering column assembly also includes a steering shaft having an outer surface and a shaft length, at least a portion of the steering shaft located within the bore defined by the inner surface of the jacket. The steering column assembly further includes a stiffening sleeve having a radially inner surface, a radially outer surface, and a sleeve length, wherein the radially outer surface of the stiffening sleeve is fixed to the inner surface of the jacket.