Telescopic Steering Shaft Backup Locking for Torque Reliability
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Solution Overview
Problem
Existing steering shafts face challenges in maintaining smooth adjustment and safety during emergencies when rolling bodies fail, leading to increased friction and potential loss of steering function.
Innovation Solution
A steering shaft design featuring a securing element with supporting bodies that are spaced apart from the inner and outer shafts in normal operation, allowing for frictionless movement but engaging to form a positive locking connection in emergencies to transmit torque, ensuring continued steering functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a securing element with supporting bodies is provided to ensure basic steering function when rolling bodies fail, then reliability is improved, but friction increases and adjusting force becomes too high
Solution Approach 1:
The supporting bodies are designed to be movable relative to the rolling bodies, allowing them to dynamically engage when rolling bodies fail. The supporting bodies can move in the longitudinal direction and rotate about the longitudinal axis, transitioning from a non-engaged state during normal operation to an engaged state when needed, thus providing reliability without increasing normal operating force.
Solution Approach 2:
The securing element with supporting bodies is extracted as a separate, independent component from the main rolling body system. This allows the supporting bodies to function as a backup system that only activates when needed, rather than being permanently engaged and causing continuous friction during normal steering operation.
2Reliability
If supporting bodies are arranged to engage in rolling body raceways for torque transmission, then reliability is improved, but device complexity increases
Solution Approach 1:
The supporting bodies are designed to serve multiple functions: they can transmit torque when engaged, guide the movement of rolling bodies, and provide structural support for the securing element. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while still improving reliability.
Solution Approach 2:
The supporting bodies are nested within the securing element structure, with each supporting body positioned to engage with the rolling body raceways. This nested arrangement allows the supporting bodies to be integrated into the existing steering shaft structure without requiring completely separate external components, thus managing device complexity.
3Reliability
If supporting bodies are fixed in position to ensure positive locking, then torque transmission is reliable, but manufacturing precision requirements increase
Solution Approach 1:
Instead of fixing supporting bodies in rigid positions, the invention allows them to move dynamically to achieve engagement. The supporting bodies can adjust their position in the longitudinal direction and rotate, which compensates for manufacturing tolerances and reduces the precision required during manufacturing while still ensuring reliable positive locking when engaged.
Solution Approach 2:
The invention changes the positional parameters of the supporting bodies from fixed to variable. By allowing the supporting bodies to move and adjust their position, the system can accommodate variations in manufacturing precision while still achieving the required engagement and torque transmission reliability.
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 design prevents undesired force adjustments and ensures reliable torque transmission during failures, providing increased safety and redundancy without impairing normal operation.
Implementation Method 1
the rolling bodies roll with low rolling friction, with the result that they can be inserted virtually without play between the rolling body raceways
Implementation Method 2
At the same time, the rolling bodies serve as positively locking elements for the transmission of the torque which is introduced for steering purposes from the inner shaft to the outer shaft
Data Source
AI summary
A steering shaft for a motor vehicle includes a hollow outer shaft with a longitudinal axis. An inner shaft is arranged coaxially within the outer shaft. The inner shaft telescopes longitudinally relative to the outer shaft and is connected in a torque-transmitting manner to the outer shaft via a rolling body. The rolling body can roll in the direction of the longitudinal axis and the rolling body bearing in a positively locking manner in the circumferential direction about the longitudinal axis between rolling body raceways on the inner and outer shaft. The steering shaft includes a securing element with a supporting body arranged between supporting faces configured on the inner shaft and on the outer shaft, which at least one supporting body can be supported in a positively locking manner in the circumferential direction. The supporting body is spaced apart in the circumferential direction from the supporting faces.