Elevator Brake Safety Circuit for In-Motion Partial Stroke Testing
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Solution Overview
Problem
Conventional elevator systems face challenges in testing the operation of safety actuators, such as relays and transistors, which either introduce noise during stationary tests or require elevator motion interruption for functional verification.
Innovation Solution
An elevator safety circuit using transistors, particularly MOSFETs, is designed to perform a partial stroke test while the elevator is in motion, ensuring the safety circuit's functionality without interrupting operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional relay-based safety actuators are tested while the elevator is stationary, then the testing can be performed without motion interruption, but noise is introduced during the test
Solution Approach 1:
The patent replaces mechanical relay actuators with electronic transistor-based actuators in the safety circuit. This substitution eliminates the mechanical switching noise inherent in relay-based systems while maintaining the safety function. The transistor-based actuators can be tested without introducing noise, resolving the contradiction between continuous operation and noise-free testing.
Solution Approach 2:
The patent implements periodic testing of the safety actuators during normal elevator operation rather than requiring stationary testing. By conducting tests periodically during motion, the system maintains operational continuity while avoiding the noise issues associated with stationary relay testing. The controller selectively activates actuators at appropriate intervals to verify safety circuit functionality.
2Object-affected harmful factors
If transistor-based actuators are used in the safety circuit, then noise during operation is eliminated, but testing requires elevator motion which interrupts operation
Solution Approach 1:
The controller is configured to periodically test the transistor-based actuators during normal elevator operation. By conducting tests during motion rather than requiring stationary conditions, the system maintains operational continuity while verifying safety circuit functionality. This periodic testing approach eliminates the need to interrupt service for safety verification.
Solution Approach 2:
The safety circuit testing is integrated into the normal operation of the elevator system. The controller automatically performs tests during regular operation without requiring external intervention or service interruption. The system serves itself by continuously verifying safety actuator functionality as part of normal operation, eliminating dedicated testing downtime.
3Reliability
If full brake application testing is performed, then complete safety functionality is verified, but elevator motion must be interrupted
Solution Approach 1:
The patent implements partial stroke testing of the brake actuator during normal operation, where the actuator is activated partially to verify functionality without applying full brake force. This partial action approach verifies safety circuit operation while maintaining elevator motion, avoiding complete motion interruption. The controller monitors the partial activation to ensure proper actuator response without requiring full safety brake application.
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
The solution allows for reliable testing of safety actuators without noise interference and operational disruption, enhancing safety and user experience by ensuring the brake system operates correctly without full application.
Implementation Method 1
an electromagnet-based device. When the electromagnet is engaged (i.e. when the coil of the electromagnet is supplied with a current), the electromagnet separates the frictional brake mechanism
Data Source
Figure 1~2B
Figure 3
Figure 4
AI summary
An elevator safety circuit (24) for an elevator system in which an output is arranged to selectively provide an electrical current from an input to an electromagnetic brake coil (18) via a current flow path. An actuator transistor (34, 36) is arranged in series along the current flow path between the input and the output, the actuator transistor being arranged to selectively allow passage of the electrical current. A controller (38) is arranged to carry out a test operation when the braking element (14) is in the open position. The test operation comprises operating the actuator transistor (34, 36) in its disabled mode for a time period, monitoring the electrical current through the brake coil (18), and determining whether the magnitude of the electrical current reduces during said time period, the time period being selected such that the magnitude of the electrical current remains sufficient for keeping the braking element (14) in the open position during the test.