Machinery Brake Control via Inductance Estimation
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Solution Overview
Problem
Normally-closed machinery brakes used in elevators experience wear-related issues with position sensors and produce disturbing noise during opening and closing, which existing solutions fail to adequately address in terms of wear-resistance and noise reduction.
Innovation Solution
A system comprising an estimation and control loop that uses the inductance of a magnetizing coil to estimate the air gap and adjust the current, allowing for indirect measurement and control of the brake without direct feedback from a potentiometer, and adjusts the voltage connected to the magnetizing coil to dampen noise by controlling the air gap values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a potentiometer is used to detect the position of the brake shoe, then the control precision is improved, but the wear resistance deteriorates due to continuous contact and wear
Solution Approach 1:
The patent replaces the mechanical potentiometer-based position detection system with an inductance-based electrical measurement system. The inductance of the magnetizing coil changes with the air gap distance, allowing contactless measurement of the brake shoe position. This substitution eliminates mechanical wear while maintaining measurement precision.
Solution Approach 2:
The patent introduces the inductance of the magnetizing coil as an intermediary parameter to indirectly measure the air gap distance. Instead of directly measuring position with a potentiometer, the system measures the inductance change caused by the varying air gap, which then serves as a proxy for position detection.
2Speed
If a powerful closing spring is used to quickly close the brake shoe, then the response speed is improved, but the noise level increases due to impact noise during closing
Solution Approach 1:
The patent implements a feedback control system that continuously monitors the inductance (and thus the air gap distance) and adjusts the magnetizing coil current accordingly. During closing, the system detects the approaching brake shoe through inductance changes and reduces the closing force before contact, preventing impact noise while maintaining quick response.
Solution Approach 2:
The patent dynamically adjusts the magnetizing coil current based on the real-time air gap distance. Instead of using a fixed powerful closing spring force, the system varies the electromagnetic force dynamically during the closing process, reducing force as the brake shoe approaches the drum to eliminate impact while maintaining speed.
3Object-generated harmful factors
If the magnetizing coil current is reduced to lessen impact sound, then the noise level is improved, but the response time increases due to slower brake shoe movement
Solution Approach 1:
The patent performs preliminary action by using the inductance feedback to anticipate the brake shoe position and pre-adjust the magnetizing coil current before the brake shoe makes contact. This allows the system to prepare the optimal current level in advance, ensuring both quick response and minimal impact noise.
Solution Approach 2:
The patent employs dynamic current adjustment where the magnetizing coil current is continuously optimized based on the real-time air gap measurement. The system applies high current when the air gap is large for quick movement, then smoothly reduces current as the brake shoe approaches, maintaining both speed and noise reduction.
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 solution improves wear-resistance and diversifies control of the machinery brake, reducing noise during normal operation without the need for a wearing potentiometer and allows for soft opening and closing, while maintaining quick closure in emergency situations.
Implementation Method 1
A normally-closed machinery brake refers to the type of machinery brake that has at least one magnetizing coil, which when it is energized the closed machinery brake opens
Implementation Method 2
when it is de-energized the opened machinery brake closes and remains closed, usually when forced by the spring force bringing about the closing
Implementation Method 3
at least one air gap estimator, which is configured to produce an estimated air gap value on the basis of an input by measuring the inductance of a magnetizing coil
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The system (20, 30) for controlling the opening and/or closing of a normally-closed machinery brake (1) opening by means of at least one magnetizing coil (9) and closing by means of at least one closing spring (3) comprises: at least one estimation and control loop (20) according to the invention and at least one measuring and control circuit (30) according to the invention, which are connected or can be connected to each other, and of which a) the estimation and control loop (20) is configured to use an input (I (t) ) produced by the measuring and control circuit (30), and b) the measuring and control circuit (30) is configured to use the modulation reference (U3B) produced by the estimation and control loop (20) for connecting the voltage (U9) to be connected over the magnetizing coil (9).