Elevator Brake Control Circuit Isolation for Contact Adhesion
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Solution Overview
Problem
The adhesion of contacts in existing elevator braking systems' contracting brake circuits leads to safety issues due to excessive current flowing through the contacts, causing brake failure and potential accidents.
Innovation Solution
A control circuit and method that separates the brake excitation coil from the contracting brake circuit, using a contracting brake signal generating circuit, a level conversion circuit, and an isolation control switch to control the brake excitation coil directly through a braking controller, reducing the current flowing through the contacts to several tens of milliamperes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the brake excitation coil is series connected in the contracting brake circuit, then the brake can be controlled to contract and release, but the current flowing through the contacts becomes excessively large causing contact adhesion
Solution Approach 1:
The brake excitation coil is extracted from the contracting brake control circuit. The control circuit now only handles signal generation and logic control, while the excitation coil is directly controlled by the braking controller based on signals from the control circuit. This separation removes the high current load from the control contacts, eliminating contact adhesion while preserving brake control functionality.
Solution Approach 2:
A braking controller is introduced as an intermediary device between the contracting brake circuit and the brake excitation coil. The controller receives control signals from the circuit and independently manages the high current required by the excitation coil. This intermediary protects the control contacts from excessive current while maintaining the control-coil relationship.
2Ease of operation
If the switch contacts carry both excitation current and continuous coil current, then the brake control function is maintained, but the contacts experience severe arcing and adhesion
Solution Approach 1:
The continuous coil current path is extracted from the control circuit. The control circuit switches only generate low-current logic signals, while the braking controller separately manages the continuous high current to the excitation coil. This eliminates the叠加 effect of excitation current plus continuous current on the contacts, preventing severe arcing.
Solution Approach 2:
The braking controller serves as an intermediary that handles the continuous current load, isolating it from the control circuit's switch contacts. The controller maintains the brake's operational state through continuous low-current signaling while managing the high current separately, thus preventing contact arcing.
3Power
If high current flows through the contracting brake circuit contacts, then the brake excitation coil can be activated, but the contacts suffer from adhesion leading to brake failure
Solution Approach 1:
The high power excitation coil circuit is extracted from the low-power control circuit. The control circuit maintains full brake control capability through signal generation, while the excitation coil receives high current directly from the power supply through the braking controller. This separation allows high power delivery without compromising control circuit reliability.
Solution Approach 2:
The braking controller acts as a power intermediary that decouples the high power requirement from the control circuit. It receives low-power control signals and converts them into high-current excitation output, enabling the system to deliver necessary brake power while protecting the control circuit from power-related reliability issues.
Data Source
AI summary
Circuits and methods for controlling an elevator braking system are provided. A circuit for controlling an elevator braking system includes a contracting brake signal generating circuit, wherein a door lock relay DJ and a contracting brake contractor ZJ are series connected; a contracting brake signal processing circuit, for converting between high and low level to trigger a braking controller; and an isolation control switch CK jointly connected in the contracting brake signal generating circuit and the contracting brake signal processing circuit.