Steering Rod Damping Element for Axial Stroke Control
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Solution Overview
Problem
Standardized motor vehicle steering systems face challenges in adapting to different vehicle types and models, as existing mechanical and software end stops either impose uniform axial stroke limitations or fail to prevent wheel collisions with the wheel arch, especially when de-energized.
Innovation Solution
An electromechanical motor vehicle steering system with a damping element made of elastomeric material, which is compressible by the electric motor during operation to limit axial stroke and provide a larger turning circle, while maintaining sufficient resistance in the de-energized state to prevent wheel collisions, allowing for standardization across various vehicle types and models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical end stop is provided to limit axial stroke, then the turning circle is restricted, but the wheel collision problem is prevented
Solution Approach 1:
The patent applies a dynamic damping element that changes its mechanical properties based on the operational state. During powered operation, the damping element is compressed and becomes less rigid, allowing larger axial stroke for smaller turning circles. During de-energized state, the damping element returns to its original rigid state, providing mechanical end stop to prevent wheel collisions. This dynamic behavior resolves the contradiction between turning circle size and collision prevention.
Solution Approach 2:
The damping element's stiffness parameter changes dynamically based on compression state. When compressed during powered operation, the element exhibits lower stiffness allowing extended axial travel. When uncompressed during de-energized state, the element exhibits high stiffness providing mechanical limitation. This parameter change enables the system to adapt axial stroke limits based on operational conditions, resolving the contradiction between turning circle size and wheel collision prevention.
2Ease of manufacture
If a standardized steering system is used across different vehicle types, then manufacturing costs are reduced, but adaptation to different vehicle requirements becomes difficult
Solution Approach 1:
The damping element serves multiple functions: during powered operation it enables extended axial stroke for compact turning circles, during de-energized state it provides mechanical end stop to prevent wheel collisions. This multi-functionality allows a single standardized component to address different vehicle requirements without hardware changes, resolving the contradiction between standardization and adaptability.
Solution Approach 2:
The dynamic characteristics of the damping element allow the same standardized steering system to adapt to different vehicle types. The element's state-dependent stiffness automatically adjusts the effective axial stroke limit based on operational conditions, enabling a universal design to meet both compact turning circle requirements and wheel collision prevention needs across different vehicle platforms.
3Ease of operation
If software end stop is used to limit axial stroke, then the turning circle is not restricted, but the system fails when de-energized
Solution Approach 1:
The damping element acts as a mechanical intermediary that bridges the powered and de-energized states. During powered operation, it works with the electric motor to enable extended axial stroke. During de-energized state, it provides passive mechanical end stop without requiring electrical power. This intermediary component ensures continuous reliability of the end stop function across all operational states, resolving the contradiction between turning circle size and system 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
The system achieves reliable axial stroke limitation and prevents wheel collisions with the wheel arch across different vehicle types and models, enabling the largest possible turning circles during normal operation and accommodating varying vehicle requirements without hardware changes.
Implementation Method 1
a damping element (8) is provided on the motor vehicle steering system (1). Its elasticity is matched to the axial forces acting on the steering rod (3) in such a way as to form an axial end stop for an axial force applied, for example, by the driver via the steering handle (4) when the motor vehicle steering system (1) is deenergized
Implementation Method 2
the elasticity of the damping element (8) is selected such that, when the motor vehicle steering system (1) is de-energized, it can be oversteered by the axial force applied by the driver via the steering handle (4) and preferably remains largely uncompressed
Data Source
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AI summary
An electromechanical motor vehicle steering system (1) comprises a steering gear housing (2), a steering rod (3) which is arranged in axially movable fashion in the steering gear housing (2) and which is axially displaceable by means of a steering handle at the driver, and an electric motor which is coupled to the steering rod (3) for the axial displacement thereof, wherein the axial travel of the steering rod (3) is limited. For limitation of the axial travel, a damping element (8) is provided, the elasticity of which is configured so as to form an axial end stop, which opposes an axial force, in an electrically deenergized state of the motor vehicle steering system (1), but, in the electrically energized state of the motor vehicle steering system, can be overridden by the axial force imparted by the electric motor, such that, in the electrically deenergized state, the limitation of the axial travel of the steering rod (3) occurs at a smaller axial travel than in the electrically energized state of the motor vehicle steering system (1).