Telescopic Steering Shaft Pull-Out Protection
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Solution Overview
Problem
Telescoping steering shafts for motor vehicles face challenges in providing a simplified structure that ensures secure assembly and prevents unintended disassembly, while maintaining low-friction and noise-free operation to compensate for dynamic changes and enhance crash safety and ergonomics.
Innovation Solution
A shaft design featuring an inner tube with a resilient blocking element for pull-out protection, which is integrated within the inner tube and engages behind an undercut in the outer tube, providing a self-locking mechanism to prevent pull-out and allowing for easy assembly by compressing and expanding to form a barb, thus ensuring secure attachment without additional complex assembly steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pull-out safeguard is provided to prevent the inner tube from slipping out of the outer tube during transport and assembly, then the reliability of the shaft is improved, but the device complexity increases due to additional components and assembly steps
Solution Approach 1:
The pull-out safeguard is integrated into the inner tube itself by forming the resilient blocking element as a one-piece component with the inner tube. This merging of the safeguard function into the existing inner tube structure eliminates the need for separate pull-out protection components and reduces assembly steps, thereby improving reliability without significantly increasing device complexity.
Solution Approach 2:
The resilient blocking element automatically engages with the undercut on the outer tube during the normal assembly process. When the inner tube is inserted into the outer tube, the blocking element is compressed and then springs back to engage behind the undercut, providing self-locking protection against pull-out without requiring additional assembly operations. This self-service mechanism ensures reliable pull-out protection while maintaining simple assembly procedures.
2Reliability
If a resilient blocking element is used to limit pull-out of the inner tube, then the reliability is improved, but the ease of manufacture deteriorates due to the need for additional forming operations
Solution Approach 1:
The resilient blocking element is formed as an integral part of the inner tube in a one-piece manufacturing process. By combining the inner tube and blocking element into a single component, the patent eliminates the need for separate manufacturing and assembly operations for the safeguard element. This integration maintains manufacturing simplicity while ensuring reliable assembly security through the self-engaging blocking mechanism.
3Strength
If the inner tube is guided in a rotationally fixed manner to transmit torque, then the strength of torque transmission is improved, but the ease of operation worsens due to increased friction and potential noise during telescoping
Solution Approach 1:
The shaft is divided into functionally distinct segments: the inner tube with the resilient blocking element handles axial telescoping movements, while the outer tube with the undercut provides rotational guidance and torque transmission. This segmentation allows each component to optimize its specific function - the inner tube can telescope smoothly with minimal friction, while the outer tube ensures rotationally fixed guidance for reliable torque transmission, thereby resolving the contradiction between strength and ease of operation.
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 enables a simple and secure assembly process, provides high resistance against unintended pull-out, and maintains low-friction operation by using resilient locking elements that only engage when necessary, ensuring the telescoping shaft functions smoothly and quietly, even under dynamic conditions.
Implementation Method 1
the pull-out safeguard has at least one resilient blocking element for positively limiting the pull-out of the inner tube from the outer tube
Data Source
Figure 1~3
AI summary
The present invention relates to a shaft (1) for steering a motor vehicle, comprising an outer tube (3) and an inner tube (2) telescopic relative to the outer tube (3), wherein the inner tube (2) is guided in a rotationally fixed manner in the outer tube (3) in order to transfer a torque, and an innerlying end (26) of the inner tube (2) is received in the outer tube (3). A withdrawal safeguard mechanism (5) is provided on the innerlying end (26) of the inner tube (2) to limit the withdrawal of the inner tube (2) out of the outer tube (3) and said withdrawal safeguard mechanism (5) has at least one resilient blocking element (54) for interlockingly limiting the withdrawal of the inner tube (2) from the outer tube (3).