Brake Fluid Pressure Filtering for Rotor Thickness Oscillations
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Solution Overview
Problem
The variation in brake rotor thickness due to unintended contact between brake pads and the rotor causes oscillations in brake fluid pressure, leading to unstable control of brake fluid flow and inaccuracy in achieving target pressure, which affects the stability and accuracy of the braking system.
Innovation Solution
A filtering system that uses a pressure sensor to measure brake fluid pressure and applies filters based on the rotational frequency of the wheel, such as a two-pole resonator or notch filters, to attenuate these oscillations and maintain a stable brake fluid pressure, thereby improving control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If brake fluid pressure is measured directly without filtering, then the measurement reflects real-time pressure changes, but rotor thickness variations cause oscillations that reduce measurement accuracy and control stability
Solution Approach 1:
The patent extracts and removes the oscillatory components from the brake fluid pressure signal by identifying frequency bands associated with rotor thickness variations (typically around the rotational frequency of the wheel) and eliminating these specific frequency components through filtering, while preserving the overall pressure measurement
Solution Approach 2:
The system uses feedback control by continuously monitoring the filtered brake fluid pressure and adjusting the brake fluid delivery accordingly, comparing the measured pressure against target pressure values and making real-time adjustments to maintain stable braking force application
2Measurement precision
If filtering is applied to remove oscillations, then pressure measurement accuracy improves, but system complexity increases due to additional filtering components
Solution Approach 1:
The patent replaces complex mechanical filtering components with electronic or computational filtering methods that can be implemented through software algorithms or electronic circuitry, reducing mechanical complexity while achieving the same oscillation removal effect
Solution Approach 2:
The system changes the parameter being measured from raw pressure to filtered pressure by applying transformation algorithms that modify the signal characteristics, effectively removing oscillations through mathematical operations rather than physical filtration
Data Source
AI summary
A braking control system of a vehicle includes a pressure control device that regulates brake fluid flow to a brake caliper of a wheel from a brake fluid cylinder. A pressure sensor measures a pressure of the brake fluid applied to the brake caliper. A filter module filters the measured pressure based on a rotational frequency of the wheel. The filtering produces a filtered pressure of the brake fluid applied to the brake caliper. A target pressure module sets a target pressure for the brake fluid for application to the brake caliper. A difference module determines a pressure difference between the filtered pressure and the target pressure. A pressure control module actuates the pressure control device based on the pressure difference.