Steer-by-Wire Rack Stability via Rotatable Supporting Element
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Solution Overview
Problem
Steer-by-wire steering systems in modern vehicles face challenges with high shear forces and torsional forces, leading to undesired rack rotation and increased friction, which complicates the guidance and mounting of the rack.
Innovation Solution
A steering system with a rotatably mounted supporting element, such as a pinion, that engages toothedly with the rack to transmit shear forces while blocking torque and providing stable support, combined with a recirculating ball mechanism and sensors for precise control and low-friction operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the rack is guided using conventional mounting methods in a steer-by-wire system, then the mechanical connection is simplified, but high shear forces cause undesired rack rotation and instability
Solution Approach 1:
A supporting element is introduced as an intermediary component between the rack and the housing. This supporting element receives shear forces from the rack through toothed engagement while being rotatably mounted to accommodate the forces without causing rack rotation, thus stabilizing the rack under high shear force conditions
2Stability of the object's composition
If the rack is guided with tight fitting components to prevent rotation, then rack stability improves, but friction increases and smooth movement is compromised
Solution Approach 1:
The supporting element acts as a mediator that allows the rack to move smoothly through toothed engagement while its rotatable mounting prevents excessive friction. The supporting element rotates to accommodate rack movement, maintaining low friction while the toothed engagement prevents rack rotation, achieving both stability and smooth operation
3Area of stationary object
If the supporting element is positioned close to the electric drive, then the installation space is reduced, but rack deflection occurs under high shear forces
Solution Approach 1:
The supporting element is positioned at a distance from the electric drive along the longitudinal axis of the rack, utilizing the longitudinal dimension to provide adequate support spacing. This spacing prevents rack deflection under shear forces while the overall compact design maintains space efficiency through optimized arrangement of other components
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 results in a robust, low-friction, and cost-effective steering system that maintains rack stability, reduces friction, and enhances the overall guidance of the rack, ensuring smooth operation and precise control.
Implementation Method 1
a recirculating ball mechanism (30) which interacts with the electric drive (16), the recirculating ball mechanism (30) being connected to the belt drive (18)
Implementation Method 2
a rotatably mounted supporting element (20) which is spaced apart from the electric drive (16) along a longitudinal axis of the rack (14), the rotatably mounted supporting element (20) being in toothed engagement with the rack (14)
Data Source
AI summary
A steering system (10) for a motor vehicle, which steering system (10) is configured as a steer-by-wire steering system, comprises a rack (14), an electric drive (16) for the longitudinal displacement of the rack (14), and a rotatably mounted supporting element (20) which is spaced apart from the electric drive (16) along the longitudinal axis of the rack (14), and the rotatably mounted supporting element (20) being in toothed engagement with the rack (14).