Steer-by-Wire Steering Rotation Limiter With Leadscrew Nut Stops
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Solution Overview
Problem
Existing steer-by-wire steering apparatuses face challenges in fabricating, machining, and assembling parts for rotation limiting devices, which complicates the design and packaging, and can damage clock springs due to excessive steering wheel rotation.
Innovation Solution
A steer-by-wire steering apparatus featuring a leadscrew with a first and second stopper, a nut with triangular screws, and a hollow guide ring that limits steering wheel rotation by axial sliding of the nut, allowing for easier fabrication and reduced interference with surrounding components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotation limiting device is added to prevent excessive steering wheel rotation, then driver safety and clock spring protection are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent combines the rotation limiting function with the existing leadscrew and nut mechanism. The stoppers are integrated into the leadscrew structure, and the nut incorporates both the screw thread for motion conversion and the rotation limiting feature through protrusions that interact with the stoppers. This merging eliminates the need for a separate rotation limiting device, reducing overall complexity while maintaining protective functionality.
Solution Approach 2:
The leadscrew and nut assembly serves multiple functions: it converts rotational motion to linear motion for steering control, limits rotation through the stopper-nut interaction, and provides structural support. The stoppers serve dual purposes by both limiting rotation and guiding the linear motion of the nut. This multi-functionality reduces the number of separate components needed.
2Reliability
If complex rotation limiting parts are used, then steering wheel rotation can be limited, but fabrication and machining become more difficult
Solution Approach 1:
The rotation limiting function is segmented into discrete, simple components: stoppers attached to the leadscrew and protrusions on the nut. These segmented elements are easier to manufacture individually using standard machining operations compared to a complex integrated mechanism. The segmentation allows for modular assembly and simplifies quality control during manufacturing.
Solution Approach 2:
The patent uses standard screw thread forms (first screw on the leadscrew outer circumference, second screw on the nut inner circumference) that can be produced using conventional threading operations. These standardized geometric forms are easily replicated through copying processes, ensuring consistency and ease of manufacture while maintaining the rotation limiting function.
3Reliability
If more components are added for rotation control, then steering wheel rotation is limited, but interference with surrounding components increases
Solution Approach 1:
The rotation limiting components are nested within the existing leadscrew and nut assembly. The stoppers are positioned on the leadscrew, and the nut's protrusions interact with these stoppers within the same spatial envelope. This nesting approach allows the rotation limiting function to be achieved without adding external components that would increase the overall footprint or interfere with surrounding parts.
Solution Approach 2:
The rotation limiting mechanism operates in the axial dimension of the leadscrew rather than requiring additional radial or lateral space. The stoppers extend axially from the leadscrew, and the nut's protrusions engage with them through axial movement. This dimensional approach allows rotation control without increasing the lateral footprint of the steering apparatus.
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 effectively limits steering wheel rotation, improves driver feedback, prevents clock spring damage, simplifies part assembly, and allows for versatile design and packaging of the steering apparatus.
Implementation Method 1
a leadscrew (134) coupled to a steering shaft (120) and having a first screw (201) provided on an outer circumferential portion thereof; a nut (132) having a second screw (202) provided on an inner circumferential portion thereof to engage with the first screw (201)
Data Source
AI summary
According to the present embodiments, it is possible to provide a steer-by-wire type steering apparatus which: limits a steering wheel operation of a driver within a maximum rotation angle, thereby increasing steering feel for the driver; prevents a clock spring installed on a steering wheel from being damaged, and enables parts to be manufactured and processed more easily; enables simple assembly; has small interference with surrounding parts, and thus the apparatus can be designed in various structures; and is advantageous in terms of packaging.