Rear-Axle Steering Actuator With Dual-Slider Anti-Rotation
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Solution Overview
Problem
Existing steering actuators for rear-axle steering systems face challenges in achieving a compact, robust, and production-friendly anti-rotation mechanism that effectively prevents the push rod from rotating while allowing for efficient displacement.
Innovation Solution
The steering actuator incorporates an anti-rotation mechanism with two sliding elements arranged on opposite circumferential sides of the push rod, which contact the inner wall of the housing, providing double support and minimizing radial space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anti-rotation mechanisms with protruding elements are used, then the push rod is effectively prevented from rotating, but the radial space requirement increases
Solution Approach 1:
Instead of having the anti-rotation elements protrude outward from the push rod (conventional approach), the patent inverts the arrangement by positioning the sliding elements laterally adjacent to the push rod, contacting the inner wall of the actuator housing. This inversion reduces the radial space requirement while maintaining anti-rotation effectiveness through the dual support configuration.
Solution Approach 2:
The patent transitions from a single-point or single-line anti-rotation support to a distributed two-dimensional arrangement with two sliding elements positioned on opposite circumferential sides. This dimensional change allows the anti-rotation function to be achieved with elements closer to the central axis, reducing radial protrusion while providing robust rotational constraint through the combined effect of both sliding elements.
2Volume of moving object
If sliding elements are arranged close to the central axis of the push rod, then radial space is minimized, but larger forces occur within the anti-rotation mechanism for a given torque
Solution Approach 1:
The patent applies the counterweight principle by positioning two sliding elements in diametrically opposite regions around the push rod. This symmetrical arrangement creates a balanced force distribution where the forces generated by each sliding element counterbalance each other, preventing net displacement of the push rod's central axis while managing the increased local forces through dual support.
Solution Approach 2:
The patent combines the anti-rotation function with a dual support system, where both sliding elements work together not only to prevent rotation but also to provide redundant load bearing. This merging of functions allows the system to handle the increased forces more effectively by distributing them across two contact points rather than relying on a single element further from the axis.
3Reliability
If polygon profiles or eccentric contours are used for anti-rotation, then the anti-rotation function is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the anti-rotation mechanism into two separate, simple sliding elements rather than using a single complex polygonal or eccentric component. This segmentation allows each sliding element to have a straightforward geometry that is easy to manufacture, while the combination of two such elements achieves the anti-rotation function that would otherwise require complex profiles.
Solution Approach 2:
The sliding elements act as intermediaries between the push rod and the actuator housing, providing the anti-rotation function through simple lateral contact rather than requiring complex form-fitting interlocking profiles. This intermediary approach simplifies the geometry of individual components while maintaining the functional effectiveness of the anti-rotation mechanism.
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 enhances the anti-rotation mechanism's robustness and compactness, allowing for larger forces to be handled within the mechanism while reducing manufacturing complexity and maintaining smooth operation.
Implementation Method 1
two sliding elements arranged on opposite circumferential sides of the push rod, i.e. positioned in mirror image to each other, each contacting an inner wall of the actuator housing
Data Source
AI summary
The invention relates to a steering actuator, in particular of a rear-axle steering system, comprising a housing and a push rod guided therein, with an anti-rotation mechanism being active between the housing and the push rod. The anti-rotation mechanism comprises two sliding elements which are disposed on opposite circumferential sides of the push rod and each contact an inner wall of the housing. The inner wall of the housing is axially parallel with the abutment faces. The sliding elements are connected to the push rod so as to be immobile in the circumferential direction and in the axial directions.