Steering Shaft Telescopic Locking Device Anti-Pullout
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Solution Overview
Problem
Existing safety devices for telescopic steering shafts in motor vehicles are complex to produce and assemble, making them inconvenient and prone to accidental dismantling, which compromises safety.
Innovation Solution
A simple and secure safety device is implemented using a stop element with a locking element that fits into a recess in the hollow shaft, providing positive fixation and preventing unintentional separation of the shafts, with a design that includes a radially slotted spring or locking ring for easy installation and secure attachment from the inside of the hollow shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety device with a stop element is provided to prevent accidental dismantling of the steering column, then the reliability of the steering shaft is improved, but the device complexity and manufacturing complexity increase
Solution Approach 1:
The safety device is segmented into distinct functional components: a stop element with stop surface for limiting pull-out distance, and a separate connecting means with fastening elements for securing the stop element to the hollow shaft. This segmentation allows each component to be optimized independently and simplifies manufacturing and assembly.
Solution Approach 2:
The stop element is extracted as a separate, removable component from the hollow shaft, rather than being integrated into the shaft structure. This allows the stop element to be independently manufactured, inspected, and replaced if necessary, reducing overall device complexity while maintaining safety functionality.
2Reliability
If a cap-like safety device is used to limit the pull-out path of the inner shaft, then the reliability is improved, but the ease of manufacture deteriorates due to complex multi-part structure and protruding design
Solution Approach 1:
Instead of having the safety device protrude outward from the hollow shaft (cap-like design), the stop element is inverted to be received within the hollow shaft's opening cross-section. The stop surface faces the hollow shaft in the longitudinal direction, and the fastening elements secure it from the inside, eliminating the need for external caps and simplifying the overall structure.
Solution Approach 2:
The stop element and its connecting means are merged into a single integrated component that can be manufactured as one piece. The fastening elements are directly formed on the stop element, eliminating the need for separate caps, retaining rings, or multiple fastening components, thereby simplifying manufacturing and assembly.
3Ease of operation
If the stop element is fixed from the outside of the hollow shaft, then the assembly is simplified, but the reliability deteriorates due to risk of accidental dismantling
Solution Approach 1:
The stop element and its connecting means are nested within the hollow shaft's opening cross-section, with the fastening elements secured from the inside. This nested configuration provides inherent security against accidental dismantling, as the fastening elements are protected within the hollow shaft structure rather than being exposed on the outside.
Solution Approach 2:
The connecting means with fastening elements acts as an intermediary between the stop element and the hollow shaft, providing a secure mechanical connection from the inside. This intermediary structure ensures that the stop element cannot be accidentally removed while still allowing controlled assembly during manufacturing.
Data Source
Figure 1~5
Figure 6~10
AI summary
The present invention relates to a steering shaft (10) for a motor vehicle, said steering shaft comprising: an outer shaft designed as a hollow shaft (20); an inner shaft (30) which is coaxially arranged in the hollow shaft (20), is telescopic relative to hollow shaft (20) in the direction of the longitudinal axis of the steering shaft (10), and which is torque-transmittingly connected to the hollow shaft (20) via at least one positively-locking element (40); and comprising a locking device having at least one stop element (70, 700) which is fitted to the end region, facing the inner shaft (30, 300), of the hollow shaft (20, 200) and which has a stop face (78, 780) that is arranged in the opening cross section of the hollow shaft (20, 200) and that faces the hollow shaft (20, 200) in the direction of the longitudinal axis. In order provide an improved steering shaft which comprises a simple and easily mountable locking device for preventing pulling-out, the stop element (70, 700) according to the invention has at least one connecting means (74, 75, 76, 740, 741 ) which can be secured from the inside to the inner lateral surface (23) of the outer hollow shaft (20, 200) in the opening cross section.