Dual-Disk Rotor Stroke Sensor for Compact Rack-Shaft Detection
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Solution Overview
Problem
The challenge in steer-by-wire systems is to accurately detect the stroke position of a rack shaft with high precision in a compact form factor, given the limited space within the housing.
Innovation Solution
A stroke sensor is designed with two disk-shaped rotors that rotate in conjunction with the rack shaft, where at least one rotor is in direct contact with the shaft, and are arranged perpendicular to its axial direction, with inclined rotation axes to minimize size and enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional stroke sensor design is used, then the detection accuracy may be sufficient, but the sensor size becomes too large to fit in the limited housing space
Solution Approach 1:
The patent applies dimensional change by arranging two rotors side by side in the radial direction (perpendicular to the axial direction of the rack shaft) rather than stacking them axially. This radial arrangement, combined with inclining the rotation axes at 45 degrees to the radial direction, allows the rotors to be compact in the axial direction while maintaining sufficient detection accuracy through the dual-rotor configuration.
2Volume of moving object
If the rotors are arranged radially to reduce axial length, then the sensor becomes more compact, but the rotors may interfere with each other or require complex support structures
Solution Approach 1:
The patent employs asymmetry by inclining the rotation axes of the two rotors at 45 degrees to the radial direction, rather than arranging them orthogonally or parallel to the radial direction. This asymmetric angular arrangement allows the rotors to be positioned side by side in the radial direction with their planes substantially perpendicular to each other, reducing axial length while avoiding interference between the rotors and simplifying the support structure.
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 sensor achieves high-precision stroke position detection while maintaining a compact design, unaffected by housing conditions such as grease, and reduces the overall size by suppressing rotor projection.
Implementation Method 1
at least one of the two rotors is provided in direct contact with the measuring object
Data Source
AI summary
A stroke sensor is provided with two disk-shaped rotors configured to rotate with a stroke of a measuring object, a rotation detecting unit that detects rotations of the two rotors, respectively, and a stroke position detecting unit that detects the stroke position of the measuring object based on the rotations of the two rotors detected by the rotation detecting unit. At least one of the two rotors is in direct contact with the measuring object. The two rotors are provided side by side in an arrangement direction perpendicular to an axial direction of the measuring object and are provided so as to be adjacent to the measuring object in an arrangement perpendicular direction perpendicular to the axial direction and the arrangement direction. Each of the two rotors is provided in such a manner that its rotation axis direction is inclined with respect to the arrangement direction.