Steer-by-Wire Bar Anti-Rotation Sleeve
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Solution Overview
Problem
Steer by wire vehicle steering systems require an alternative means to prevent rotation of the bar about the actuation axis, as traditional components like gear teeth and pinion gears are not needed in steer by wire systems.
Innovation Solution
A vehicle steering system that includes a bar with threads, an actuator with a ball nut, and a sleeve that engages the threads of the bar to prevent rotation about the actuation axis. The sleeve is designed to clamp onto the threads, ensuring the bar does not rotate, and is constructed from plastic with a hinged design for easy installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional gear teeth and pinion gears are used to prevent bar rotation, then the bar is effectively constrained from rotating about the actuation axis, but the device complexity increases and the steering system becomes less suitable for steer-by-wire applications
Solution Approach 1:
The patent removes traditional gear teeth and pinion gears from the bar, extracting the unnecessary rotational constraint mechanism. Instead, a separate sleeve component is introduced that engages with the bar's external threads to prevent rotation, simplifying the bar's structure while maintaining the rotation prevention function.
Solution Approach 2:
The patent introduces a sleeve as an intermediary component between the bar and the housing. This sleeve engages with the bar's threads and provides the rotational constraint function, separating the actuation function (ball nut engagement) from the anti-rotation function (sleeve engagement).
2Reliability
If the sleeve is designed to clamp onto the threads of the bar, then the bar is prevented from rotating about the actuation axis, but the manufacturing precision requirements increase to ensure proper engagement
Solution Approach 1:
The bar's external threads serve multiple functions: they enable actuation through ball nut engagement for linear movement, and they provide the engagement surface for the sleeve to prevent rotation. This multi-functionality reduces the need for separate precision-critical features.
Solution Approach 2:
The sleeve is designed with features such as resilient arms and engagement protrusions that preliminarily establish proper engagement with the bar's threads during assembly. This preliminary action ensures correct positioning and reduces the need for high manufacturing precision during final operation.
3Measurement precision
If the sleeve and anti-rotation section move in unison within the housing, then the steering control precision is improved, but the device complexity increases due to the additional constraint mechanism
Solution Approach 1:
The patent combines the anti-rotation section and the sleeve into a unified moving assembly that travels together within the housing. This merging ensures they move in unison, maintaining precise steering control while reducing the number of independent components compared to separate anti-rotation and actuation mechanisms.
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 prevents the bar from rotating about the actuation axis, ensuring precise control and movement of the wheels in steer by wire vehicles, without the need for traditional gear-based mechanisms.
Implementation Method 1
The actuator has a ball nut configured to engage threads of the bar such that rotation of the ball nut moves the bar longitudinally along an actuation axis via the threads
Implementation Method 2
The sleeve can be constructed from plastic and include a flat that slidably engages a flat of the housing to prevent rotation of: i) the sleeve relative to the housing, or ii) the sleeve relative to actuation axis
Data Source
AI summary
A vehicle steering system is provided that includes a bar with threads and an anti-rotation section. An actuator having a ball nut configured to engage the threads of the bar such that the rotation of the ball nut moves the bar longitudinally along a bar axis to move one or more wheels of a vehicle. A sleeve is disposed on the anti-rotation section of the bar and non-rotatably engages the threads of the bar such that the bar is prevented from rotating about the bar axis.