Elevator Emergency Stop Reset During Power Outage Recovery
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Solution Overview
Problem
Existing elevator systems with electric actuators face challenges in operating during power outages, as the loss of power supply can activate the emergency stop device, preventing normal operation of the car.
Innovation Solution
The elevator apparatus includes a control device that determines power outage conditions and instructs the electric actuator to perform a return operation, allowing the movable element to return to a standby position, enabling the car to move to the nearest floor during power restoration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an electric actuator is used to actuate the emergency stop device, then the device complexity is reduced and space is saved, but the reliability deteriorates because the emergency stop device cannot be reset after power outage
Solution Approach 1:
The reset function is segmented from the main emergency stop mechanism and implemented as a separate motor-driven feed screw system. This allows the electromagnet to be independently reset without affecting the emergency stop functionality, resolving the contradiction by enabling reliable operation after power outage while maintaining the simple electric actuator structure.
Solution Approach 2:
The motor is activated in advance to move the feed screw and reset the electromagnet to its initial position before normal operation resumes. This preliminary action ensures the emergency stop device is ready for future emergencies while allowing the car to be operated during power restoration, thus improving reliability without increasing structural complexity.
2Ease of operation
If the electromagnet is moved closer to the movable iron core to return it to standby position, then the ease of operation is improved, but the force required increases due to stronger magnetic attraction
Solution Approach 1:
The feed screw mechanism provides dynamic, controlled movement of the electromagnet toward the movable iron core. Instead of relying solely on magnetic force, the mechanical screw system gradually reduces the gap, allowing the magnetic force to increase progressively and hold the iron core firmly in the standby position without requiring excessive force during the transition.
Solution Approach 2:
The feed screw acts as an intermediary between the motor and the electromagnet, converting rotational motion into precise linear movement. This intermediary mechanism controls the approach of the electromagnet to the movable iron core, making the reset operation easier while managing the magnetic force buildup gradually.
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 system ensures the elevator can operate during power outages by safely returning the emergency stop device to a standby state, allowing the car to stop at the nearest floor, enhancing operational reliability.
Implementation Method 1
an electromagnet that attracts the movable iron core
Implementation Method 2
The electromagnet includes a feed nut that is screwed onto a feed screw shaft. When the feed screw shaft is rotated by a motor, the electromagnet moves toward the movable iron core.
Implementation Method 3
The drive shaft is biased by a drive spring, but during normal times, movement of the drive shaft is restricted by the electric actuator
Data Source
AI summary
An elevator has a power outage operation function including an emergency stop device that is provided in the elevator car, and a drive mechanism that is configured to drive the emergency stop device. An electric actuator is configured to actuate the drive mechanism, and a control device is configured to control an operation of the car. The electric actuator includes a movable element mechanically connected to the drive mechanism, electromagnets facing the element, and a mechanism to convert rotation of a motor into linear movement of the electromagnets. When the control device determines that the electric actuator is actuated due to a power outage, the control device instructs the electric actuator to perform a return operation of returning the movable element to a standby position, and operates the car to move up and land on a nearest floor above a stop position of the car when the return operation fails.