Electric Braking Apparatus Pad Contact Detection

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Solution Overview

Problem

Existing electric braking systems face challenges in accurately detecting the pad contacting position without influencing vehicle behavior, particularly when the pad thermally expands or the detection method requires generating a certain thrust, which can affect vehicle behavior.

Innovation Solution

The electric braking apparatus detects the pad contacting position by temporarily detaching the brake pad from the rotor at a predetermined timing and using sensor signals when the pad or piston moves away, allowing for accurate positioning without generating thrust that affects vehicle behavior.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the pad contacting position is detected by bringing the pad into contact at a constant speed, then the pad contacting position can be detected, but a clearance must be constantly secured which deteriorates the response during thrust generation and may fail to detect the position when thermal expansion occurs

Engineering Contradiction:

Improvepad contacting position detection accuracyVSAvoiddetection reliability under thermal expansion

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

Instead of detecting pad contacting position by approaching the pad from a detached state (conventional method), the invention detects the position by moving the pad from a contacted state to a detached state. The detection is performed when the pad moves away from the rotor, reversing the detection sequence and eliminating the need to maintain a clearance.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The system preliminarily brings the pad into contact with the rotor before detection, ensuring that the pad is in a contacted state during detection. This preliminary contact action allows accurate detection of the contacting position without needing to maintain a clearance, and the detection is performed during the process of moving away from contact.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If a certain thrust is generated to detect the pad contacting position, then the position can be detected, but the vehicle behavior is influenced during detection

Engineering Contradiction:

Improvepad contacting position detection accuracyVSAvoidvehicle behavior influence during detection

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The invention applies only the necessary amount of thrust required to bring the pad into contact with the rotor, rather than generating excessive thrust. This partial action is sufficient for detection purposes and minimizes the influence on vehicle behavior while still enabling accurate detection of the pad contacting position.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentEP1894804B1Electric braking apparatus and vehicle provided therewith

Publication Date: 2013.06.12 HITACHI LTD

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AI summary

An electric braking apparatus (101) which first moves a piston in a detaching direction or passes a current to move the piston in the detaching direction in order to detect a pad contacting position. Furthermore, while the piston moves in the detaching direction, pad non-contact judgment is performed. After a pad non-contact state is confirmed, the piston is moved in a pressing direction to detect the pad contacting position. When the piston does not move in the detaching direction it is judged that a parking brake has an ON-state, and it is waited until a host system instructs parking brake release.