Steering Shaft Redundant Torque via Nested Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing steering shafts lack reliable redundant torque transmission mechanisms in case the primary rolling elements fail, leading to potential loss of steering functionality during extreme overload conditions.
Innovation Solution
Incorporating a coupling section with transmission bodies that engage in a loose form fit with the rolling element raceways, which transitions to a real form fit and acts as a secondary torque transmission element when the rolling elements fail, ensuring continued steering functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking element with a coupling section is provided to ensure redundant torque transmission, then reliability is improved, but device complexity increases
Solution Approach 1:
The coupling section is inserted into the hollow cross-section of the outer shaft, nesting the locking element within the existing shaft structure. This integrated design adds the redundant torque transmission function without requiring separate external components, thereby improving reliability while minimizing the increase in device complexity.
Solution Approach 2:
The coupling section serves multiple functions: it provides redundant torque transmission capability, maintains structural integrity during telescopic movement, and engages with rolling element raceways for force transmission. This multi-functionality allows a single component to address multiple requirements, improving reliability without proportionally increasing complexity.
2Ease of operation
If transmission elements engage in loose form fit with rolling element raceways, then ease of operation is improved, but torque transmission capacity deteriorates
Solution Approach 1:
The transmission elements dynamically transition between two engagement states: during normal telescopic operation, they engage in loose form fit allowing smooth movement; during emergency torque transmission, they transition to tight form fit engagement. This dynamic behavior resolves the contradiction by adapting the engagement characteristics to the operational requirements.
Solution Approach 2:
The transmission elements are pre-positioned within the rolling element raceways in a loose engagement state, ready to transition to tight engagement if needed. This preliminary positioning allows smooth telescopic adjustment while maintaining the capability for high-torque transmission when required, effectively preparing the system for both operational modes.
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 solution provides reliable and redundant torque transmission with minimal mechanical friction and wear during normal operation, maintaining steering precision and safety even if the primary rolling elements fail, and allows for increased torque transmission capacity in emergency scenarios.
Implementation Method 1
at least one, and usually several, rolling elements, such as balls, form a low-friction linear rolling bearing. This ensures smooth and continuous adjustment of the inner shaft within the outer shaft along the longitudinal axis
Implementation Method 2
the coupling section has at least one transmission element which engages in a loose form fit with respect to a rotation about the longitudinal axis between the rolling element raceways of the inner shaft and the outer shaft
Data Source
Figure 1~3
Figure 4~5
Figure 6~8
AI summary
The invention relates to a steering shaft (10) for a motor vehicle, comprising a hollow outer shaft (20) in which an inner shaft (30) is coaxially and telescopically arranged and which is torque-transmittingly connected to the outer shaft (20) via at least one rolling element (40), wherein in the circumferential direction relative to a rotation about the longitudinal axis (L) the rolling element (40) interlockingly contacts the inner shaft (30) and the outer shaft (20) between rolling element races (22, 32). The steering shaft comprises a securing element (70), which is fixed on the outer shaft (20) and has a coupling section (72), via which the inner shaft (30) and the outer shaft (20) can be torque-transmittingly connected. For improved redundant torque transmission in the event of a failure of rolling elements (40), the coupling section (72) has at least one transmission element (8) which loosely interlockingly engages between the rolling element races (22, 32) of the inner shaft (30) and the outer shaft (20) in relation to a rotation about the longitudinal axis (L).