Adjustable Steering Shaft Stop Layer for Quiet Pull-Out Protection
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Solution Overview
Problem
Existing length-adjustable steering shafts face issues with noise and risk of damage due to metal-to-metal contact during steering column adjustment, restricting design freedom and causing unpleasant tactile feedback.
Innovation Solution
A non-metallic layer is applied to at least one stop element, which is connected to the metallic surface, ensuring that when the end position is reached, a metallic surface strikes a non-metallic surface instead of another metallic one, reducing noise and impact harshness, and the layer can be made from materials like thermoplastics for optimal damping properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic stop surfaces are used in the pull-out protection device, then the steering shaft can reliably absorb maximum pull-out forces, but noise and unpleasant tactile feedback occur during steering column adjustment
Solution Approach 1:
The patent applies a non-metallic layer (such as plastic or polymer coating) to the metallic stop surfaces of the inner and/or outer stops. This composite structure combines the high strength and load-bearing capacity of metal with the noise-dampening and tactile-soothing properties of non-metallic materials, thereby resolving the contradiction between force absorption and noise reduction.
Solution Approach 2:
The non-metallic layer acts as an intermediary substance between the metallic stop surfaces. It mediates the contact interaction during pull-out operations, preventing direct metal-to-metal contact that causes noise and harsh tactile feedback, while still allowing the underlying metallic structure to provide the necessary mechanical strength.
2Object-affected harmful factors
If a non-metallic layer is applied to stop elements, then noise and impact harshness are reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The non-metallic layer is applied to the stop elements during the manufacturing process, before final assembly. This preliminary action allows the coating to be integrated into the production workflow, potentially reducing overall manufacturing complexity compared to post-assembly modifications.
Solution Approach 2:
The patent specifies that the non-metallic layer should have particular properties (thickness, material composition, bonding characteristics) to optimize both noise reduction and manufacturability. By defining specific parameter ranges, the invention balances performance improvement with manufacturing feasibility.
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 reduces noise and tactile harshness by introducing a non-metallic layer between stop surfaces, enhancing the damping effect and minimizing the risk of damage while maintaining the structural integrity of the steering shaft.
Implementation Method 1
a layer of non-metallic material is applied at least partially in the area of the stop surface to at least one of the stop elements... effectively reduces noise and tactile harshness by introducing a non-metallic layer between stop surfaces, enhancing the damping effect
Data Source
Figure 1
Figure 2~3
Figure 4~7
AI summary
The present invention relates to a length-adjustable steering shaft (2) comprising a hollow shaft (21) made of metallic material with an opening, in which an inner shaft (23) made of metallic material is accommodated torque-transmittingly and axially-movably and comprises an anti-withdrawal device with stop elements (6, 7) which include at least one outer stop (6) that protrudes into the opening (26) of the hollow shaft (21) and an inner stop (7) that protrudes outward from the inner shaft (23), wherein the stop elements (6, 7) are formed from the metallic material of the hollow shaft (21) or the inner shaft (23) and comprise stop surfaces (61, 71), which face one another in the axial direction. In order to improve the noise behavior upon impact and to achieve improved haptics, a layer (5) of non-metallic material is attached to at least part of the region of the stop surface (61, 71) of at least one of the stop elements (6, 7).