Adjustable Steering Shaft Sleeve Mounting for Low-Friction Assembly
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Solution Overview
Problem
The existing steering shaft systems require precise manufacturing and assembly to minimize friction and angular clearance, leading to high production and assembly costs due to the external fastening of the profiled sleeve, which can be influenced by slight deformations or tolerances.
Innovation Solution
The fastening portion of the profiled sleeve is connected internally to the inner shaft, eliminating the need for external fixing elements and allowing for a longer bearing region, thus reducing the impact of manufacturing tolerances on friction and enabling deeper insertion of the inner shaft into the outer shaft, enhancing energy absorption without compromising bearing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the profiled sleeve is fixed externally on the inner shaft, then the sleeve can be securely attached, but the friction during axial adjustment increases and manufacturing precision requirements become more stringent
Solution Approach 1:
The patent inverts the conventional external fastening approach by implementing internal fastening. The fastening portion of the profiled sleeve extends into the hollow interior of the inner shaft and connects to the inner surface, reversing the traditional outside-to-inside fastening logic. This internal connection eliminates the need for external fastening elements that interfere with functional surfaces, thereby reducing friction during axial adjustment while maintaining secure attachment.
2Manufacturing precision
If narrow tolerances are observed in manufacture and assembly, then angular clearance is minimized, but production and assembly costs increase
Solution Approach 1:
The patent extracts the fastening function from the external surface of the inner shaft and relocates it to the internal hollow space. By taking out the external fastening elements and implementing internal fastening through the hollow interior, the design eliminates the need for precise external positioning and alignment, thereby reducing manufacturing tolerances requirements and associated costs while maintaining angular clearance minimization.
3Manufacturing precision
If the profiled sleeve is positioned precisely, then friction during adjustment is reduced, but assembly complexity increases
Solution Approach 1:
The patent merges the fastening function and the positioning function into a single integrated internal structure. The fastening portion that extends into the hollow interior simultaneously provides both secure attachment and precise positioning, eliminating the need for separate external fastening elements and complex alignment procedures. This integration reduces assembly complexity while maintaining positioning precision and minimizing friction during adjustment.
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 internal connection reduces the complexity and cost of assembly, allows for greater tolerances, and enhances energy absorption during crashes without affecting the torque transmission, thereby simplifying the manufacturing process and improving the steering shaft's performance.
Implementation Method 1
The profiled sleeve is manufactured from or coated with a material that is readily slidable on steel, preferably a plastics material such as polypropylene (PP), polytetrafluoroethylene (PTFE) or the like
Data Source
AI summary
A length-adjustable steering shaft for a motor vehicle may include a hollow outer shaft with an unround inner cross section, in which an inner shaft is received in a torque-locked and axially movable manner. A profiled sleeve may be arranged between the inner shaft and the outer shaft, and the profiled sleeve may have a fastening portion connected to the inner shaft. The inner shaft may be configured at least in part as a hollow shaft that has an interior that is open towards the end that is inserted into the outer shaft. To reduce the outlay in terms of production and assembly, the fastening portion may extend from the end into the interior of the inner shaft and is connected to an inner surface of the interior.