Brake Pad Clearance Control Using Sensor Delay Correction
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Solution Overview
Problem
Existing brake systems face challenges in accurately detecting the contact position between a brake pad and a disc due to sensor noise and delay time differences, leading to inaccurate clearance control, which results in increased drag during non-braking and reduced responsiveness during braking.
Innovation Solution
A brake system that includes a brake disc, a brake pad, a piston, a position sensor, a thrust sensor, and a brake control unit with a contact position computation unit, position error computation unit, and contact position correction unit to accurately compute and correct the contact position, accounting for delay time differences between sensor signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the detection threshold value of the thrust sensor is reduced to improve contact position detection accuracy, then measurement precision improves, but reliability deteriorates due to sensor noise and characteristics that cause rapid deterioration near thrust of 0
Solution Approach 1:
The system performs preliminary action by detecting the rate of change of thrust sensor output before actual contact occurs. By monitoring how quickly the thrust changes as the brake pad approaches the disc, the system can predict the contact moment in advance, allowing for more accurate contact position detection without relying on threshold values near zero where sensor reliability is poor.
Solution Approach 2:
The system uses feedback by continuously monitoring the rate of change of the thrust sensor output and comparing it against expected patterns. This feedback mechanism allows the system to distinguish between actual contact events and sensor noise, improving both measurement precision and reliability by validating detections against physical expectations of the braking process.
2Use of energy by moving object
If the gap between brake pad and disc is increased during non-braking to reduce drag and improve fuel efficiency, then fuel efficiency improves, but braking response deteriorates due to longer distance for the brake pad to reach the disc
Solution Approach 1:
The system performs preliminary action by detecting the approach of the brake pad toward the disc through monitoring the rate of change of thrust. This early detection allows the control system to prepare for braking in advance, compensating for any increased initial gap by anticipating the contact moment and initiating control actions before actual contact occurs, thereby maintaining fast braking response despite larger non-braking gaps.
3Speed
If clearance control is optimized to maintain narrow gap during non-braking to improve braking response, then braking response improves, but fuel efficiency deteriorates due to increased drag of the brake pad
Solution Approach 1:
The system applies dynamics by dynamically adjusting the clearance based on detected braking intent. During non-braking periods, the system maintains larger clearance to reduce drag and improve fuel efficiency. When braking is detected through thrust sensor monitoring, the system dynamically reduces the gap to ensure rapid brake pad-disc contact, thus optimizing both fuel efficiency and braking response through time-varying clearance control.
Data Source
AI summary
An object of the present invention is to appropriately control a clearance amount by correcting an estimation error of a contact position caused by a delay time difference between output signals of sensors, and to establish both improvement of fuel efficiency due to prevention of drag of a brake pad during non-braking and reduction in response time during braking.A brake system includes a brake disc, a brake pad, a piston, a drive mechanism, a position sensor that detects a position of the piston, a thrust sensor that detects a thrust by which the brake pad presses the brake disc, and a brake control unit that adjusts a braking force by controlling the drive mechanism. The brake control unit includes a contact position computation unit that computes a contact position at which the brake pad and the brake disc come in contact with each other based on output signals of the position sensor and the thrust sensor, a position error computation unit that computes a position error of the contact position based on a delay time difference between the output signals of the position sensor and the thrust sensor, and a contact position correction unit that corrects the contact position obtained by the contact position computation unit by using the position error.