Disc Brake Rotor Evaluation Using Angular Interpolation
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Solution Overview
Problem
Current methods for evaluating dimensional variations on brake rotors provide limited information, lacking specific high and low value data and angular location, and are not capable of performing comprehensive rotor analyses and diagnostics effectively.
Innovation Solution
A method that converts chronologically spaced samples into equiangularly spaced samples by measuring rotor variations as a function of time and angular location, using non-contact displacement capacitive sensors and signal processing to display and record these variations, and performing harmonic analysis and spline-based interpolation to account for rotor speed variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chronologically spaced samples are taken during rotor rotation, then measurement process is simple and fast, but measurement precision is insufficient due to rotor speed variations
Solution Approach 1:
The system uses a reference marker detected by a sensor to provide feedback on rotor angular position. This feedback enables the processor to determine the actual angular displacement between samples and compensate for speed variations, thereby maintaining measurement precision while allowing continuous rotation without speed control.
Solution Approach 2:
The system transforms the measurement parameter from time-based sampling to angular-position-based sampling. By using the reference marker to establish angular positions and interpolating dimensional variations as a function of angular position rather than time, the system compensates for speed variations and achieves precise dimensional measurement during continuous rotation.
2Measurement precision
If rotor speed is controlled to ensure constant rotation, then measurement precision improves, but device complexity increases
Solution Approach 1:
The system replaces the mechanical speed control system with an electronic/software-based compensation method. Instead of using mechanical devices to maintain constant rotational speed, the patent uses a processor to detect reference markers and mathematically interpolate dimensional variations based on angular position, eliminating complex mechanical speed control mechanisms.
3Loss of information
If comprehensive rotor analysis with harmonic analysis and interpolation is performed, then measurement precision and diagnostic capability improve, but device complexity increases
Solution Approach 1:
The processor automatically performs harmonic analysis and spline-based interpolation on the collected dimensional variation data. The system self-processes the raw measurements to extract meaningful diagnostic information such as runout values, thickness variations, and patterns indicating manufacturing defects, eliminating the need for manual analysis while providing comprehensive rotor evaluation.
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 method allows for accurate pinpointing of rotor irregularities, wheel speed compensation, and presentation of results in a three-dimensional view, enabling detailed analysis of rotor geometry and identifying causes of wear, such as cast cooling issues or die imperfections.
Implementation Method 1
non-contact displacement capacitive sensors
Data Source
AI summary
A method for determining local departures of opposed friction surfaces that are spaced apart in parallel planes normal to the axis of the rotor. Displacement sensing probes are placed in opposing alignment adjacent the friction surfaces and rotor is spun. Instantaneous distances from each probe to the friction surfaces is made by repetitively sampling and converting the sample distances into digital form. The differences between contemporaneous sample distances are computed to determine rotor thicknesses and displayed. An analog measure of the instantaneous angular rotor position is provided for each instantaneous angular position. The angular rotor position and distance measures are correlated and the angular rotor position sample converted to digital form. While the time interval between successive distance samples is constant the rotor angular velocity may vary during a revolution and spline-based interpolation between successive distance samples is performed to obtain to obtain a representation of equiangularly spaced sample values.