Brake Clearance Detection via Wear Sensor Oscillation Analysis
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Solution Overview
Problem
Existing methods for detecting brake clearance in motor vehicles, such as EP 2 520 817 A1, face challenges in accurately determining clearance due to disruptive influences like elastic caliper expansion, making it difficult to measure wear accurately without auxiliary variables, especially when the clearance is below 1 mm.
Innovation Solution
A method that involves reading measurement signals from a wear sensor, identifying a characteristic oscillation in the signal profile when the brake lining contacts the counterpart, and determining the clearance by calculating the difference between the event signal value and the output signal value, which is representative of the non-actuated state, allowing for high accuracy and reliability without accounting for disturbance variables like elastic caliper expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the wear sensor measures the displacement of the feed unit to determine clearance, then the detection method is simple and low-cost, but the measurement accuracy deteriorates due to disruptive influences like elastic caliper expansion
Solution Approach 1:
The patent utilizes the characteristic signal oscillation (mechanical vibration) that occurs when the brake lining contacts the brake disk/drum. This vibration signature serves as a precise indicator of the clearance state, allowing accurate measurement without being affected by elastic caliper expansion or other disturbance variables. The oscillation detection transforms an otherwise noisy displacement signal into a reliable clearance measurement.
2Ease of manufacture
If the wear sensor measures displacement without considering disturbance variables, then the equipment costs remain low, but the reliability of clearance detection deteriorates
Solution Approach 1:
The patent converts the harmful effect of elastic caliper expansion and other disturbance variables into a beneficial signal. By analyzing the characteristic oscillation that occurs during brake lining contact, the system transforms what would otherwise be noise and errors into a reliable indicator of clearance state. This approach maintains low equipment costs while significantly improving detection reliability.
3Productivity
If the clearance is below 1 mm, then the brake system operates efficiently, but the measurement becomes increasingly difficult due to elastic caliper expansion
Solution Approach 1:
For small clearances below 1 mm, the patent relies on detecting the characteristic mechanical vibration signal that occurs when the brake lining makes contact with the brake disk or drum. This vibration-based approach provides sufficient signal amplitude and clarity even for sub-millimeter clearances, overcoming the difficulty of measuring such small distances in the presence of elastic caliper expansion.
Data Source
AI summary
A method (200) for detecting the clearance of a brake (100) of a motor vehicle, in particular a utility motor vehicle, includes the following steps: reading measurement signals of a wear sensor (115) disposed on the brake (100), determining an output signal value that is representative of the non-actuated state of the brake from the measurement signals, determining an event signal value that is representative of the braking state of the brake from the measurement signals, and determining the clearance from the difference between the event signal value and the output signal value, wherein the measurement signals of the wear sensor are examined for the presence of a characteristic signal oscillation that arises as a result of bringing into contact the brake lining with the counterpart thereof that is to be braked. A controller (10) carries out the method on a brake (100).