Steer-by-Wire Rotation-Limiting Assembly Soft Stop Mechanism
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Solution Overview
Problem
Conventional rotation-limiting assemblies in steer-by-wire steering systems often surprise drivers with a hard stop when reaching the maximum rotation angle, leading to discomfort due to the sudden loss of rotation capability without warning.
Innovation Solution
A rotation-limiting assembly that uses a threaded pair, sliding guide, and force fit or further sliding guide sequentially arranged in the radial direction to convert rotational movement into axial movement, with stop disks to limit rotation, providing a predefined breakaway torque that allows further rotation if exceeded, thus avoiding a hard stop and enhancing user comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hard stop is used to limit rotation at the maximum angle, then the rotation limitation is reliable and clear, but the driver experiences surprise and discomfort due to the sudden stop without warning
Solution Approach 1:
The patent introduces a soft stop mechanism using spring elements that gradually increase resistance as the steering wheel approaches the maximum rotation angle. This cushioning effect occurs before the hard stop is engaged, allowing the driver to anticipate the rotation limit through progressively increasing resistance rather than sudden cessation. The spring elements absorb the shock and provide a smooth transition, eliminating the surprising hard stop while maintaining reliable rotation limitation.
2Ease of operation
If a soft stop mechanism is introduced to improve comfort, then the driver experience is enhanced, but the device complexity increases
Solution Approach 1:
The patent combines the soft stop and hard stop mechanisms into a single integrated rotation-limiting assembly. The spring elements for the soft stop are positioned to work in conjunction with the hard stop structure, sharing common mounting points and spatial arrangement. This merging approach allows both comfort-enhancing soft stop functionality and reliable hard stop limitation to coexist without requiring entirely separate systems, thereby limiting the increase in device complexity.
Solution Approach 2:
The housing structure serves multiple functions: it provides the mounting framework for both the spring elements and the hard stop mechanism, acts as the structural boundary for the entire assembly, and facilitates the sequential engagement of soft stop followed by hard stop. This multi-functionality reduces the need for additional dedicated components, keeping the overall device complexity manageable while achieving enhanced driver comfort.
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 provides a comfortable and non-surprising rotation limitation by increasing resistance when the maximum angle is approached, allowing drivers to anticipate the limit without sudden stops, while maintaining a compact and cost-effective design.
Implementation Method 1
The threaded pair serves to convert a rotational movement of the shaft portion into a translational movement. The translational movement takes place along the center axis, i.e. axially.
Implementation Method 2
The sliding guide serves to support the torque introduced by rotation of the shaft portion and to ensure movability in the axial direction.
Implementation Method 3
the force fit couples the shaft portion to the housing in such a manner that, when a predefined breakaway torque is exceeded, the shaft portion is rotatable in relation to the housing
Data Source
AI summary
A rotation-limiting assembly for a steer-by-wire steering system is described. The rotation-limiting assembly comprises a housing, in which a shaft portion rotatable about a center axis is accommodated, wherein the shaft portion is coupled to the housing via a threaded pair, a sliding guide, and a force fit or a further sliding guide. The force fit couples the shaft portion to the housing in such a manner that, when a predefined breakaway torque is exceeded, the shaft portion is rotatable in relation to the housing. Furthermore, a first stop disk is provided on a first axial side of a sliding guide external contour of the sliding guide and a second stop disk is provided on a second axial side. Moreover, a steering wheel assembly for a steer-by-wire steering system, having such a rotation-limiting assembly is presented.