Steering Column Actuating Lever Torque Limit
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Solution Overview
Problem
Existing adjustable steering columns fail to effectively protect the driver from impacts on the actuating lever during a crash, as they either deform excessively during normal operation or detach unintentionally under improper forces.
Innovation Solution
A steering column design where the actuating lever is connected torsion-tightly with the clamp element, allowing it to rotate out of position when a torque limit is exceeded, ensuring a secure connection during normal operation and controlled detachment during a crash, with a preferred torque limit of at least 7.5 Nm to absorb energy and prevent unintended detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the actuating lever is made deformable to protect the driver during a crash, then driver protection is improved, but the lever may deform excessively during normal operation
Solution Approach 1:
The patent applies parameter changes by defining a specific torque threshold (limit value) that distinguishes between normal operation and crash conditions. The torsion-tight connection maintains high stiffness below this threshold to prevent unintended deformation, while allowing controlled rotation above it to absorb crash energy and protect the driver.
Solution Approach 2:
The connection between the actuating lever and clamp element transitions from a static rigid connection to a dynamic system with two distinct states: a torsion-tight state for normal operation and a rotatable state for crash protection. This dynamic behavior allows the system to adapt its mechanical properties based on the applied torque level.
2Object-affected harmful factors
If the actuating lever is made detachable to protect the driver during a crash, then driver protection is improved, but the lever may detach unintentionally under improper forces
Solution Approach 1:
The patent uses parameter changes by establishing a specific torque limit value that serves as a threshold for detachment. The torsion-tight connection maintains reliable attachment below this threshold to prevent unintended detachment, while enabling controlled separation above it to protect the driver during a crash.
Solution Approach 2:
The connection system transitions from a static permanently fixed state to a dynamic system with two states: a torsion-tight attached state for normal operation and a rotatable/detached state for crash protection. This allows the system to maintain reliability during normal use while providing protection when needed.
3Stability of the object's composition
If the actuating lever is rigidly connected to the clamp element, then connection stability is improved, but driver protection during crash is worsened
Solution Approach 1:
The patent applies parameter changes by introducing a torque threshold that controls the mechanical behavior of the connection. Below this threshold, the connection behaves rigidly to maintain stability; above it, the connection allows rotation to absorb impact energy and reduce force transmission to the driver.
Solution Approach 2:
The system transitions from a static rigid connection to a dynamic connection that can switch between torsion-tight and rotatable states. This dynamic capability allows the system to maintain connection stability during normal operation while providing crash protection through controlled rotation when the torque limit is exceeded.
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 provides enhanced protection for the driver during a crash by maintaining the steering column's position and ensuring proper airbag function while preventing unintended detachment under normal or improper forces, thus enhancing safety and responsiveness.
Implementation Method 1
the operating lever is preferably provided with a specified buckling point. The force leading to the deformation of the operating lever must herein be selected of adequate magnitude in order to exclude deformation during normal operation
Implementation Method 2
the actuating lever is connected torsion-tightly with the clamp element, allowing it to rotate out of position when a torque limit is exceeded
Data Source
AI summary
An adjustable steering column for a motor vehicle includes a clamping device, in the opened state of which the steering column is adjustable and in the closed state of which the set position of the steering column is fixed. The clamping device comprises an actuating lever and a clamping piece, which can be rotated about an axis of rotation by the actuating lever in order to open and close the clamping device. The actuating lever can be twisted about the axis of rotation at least in one direction of rotation with respect to the clamping piece when a limit of a torque acting between the actuating lever and the clamping piece is exceeded.