Elevator Hazard Warning Control for Car-Counterweight Approach
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Solution Overview
Problem
Elevator systems lack effective safety measures to prevent mechanics from accidentally contacting the counterweight during inspection mode, particularly when the elevator car is within a predetermined distance from the counterweight.
Innovation Solution
An approaching hazard warning system that includes a range finding sensor coupled to a warning system controller, which detects the distance between the elevator car and counterweight, and executes responsive actions such as slowing, stopping, or sounding alerts to ensure safe operation during inspection mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power is removed from the driving-machine motor and a brake is applied when the elevator car is within predetermined distance from the counterweight, then the safety of the mechanic is improved, but the operational efficiency and productivity are worsened due to frequent stopping
Solution Approach 1:
The system performs preliminary actions by issuing audible and visual warnings before the actual stop is executed. The warning system activates at a first threshold distance, giving the operator advance notice and opportunity to take corrective action before the brake is applied at a second, closer threshold distance. This preliminary warning phase allows safe operation to continue uninterrupted when possible, while still preparing for the safety stop.
Solution Approach 2:
The system dynamically adjusts its response based on the real-time distance between the elevator car and counterweight. Instead of a single static threshold, the system uses multiple dynamic thresholds (first threshold at greater distance, second threshold at smaller distance) and transitions between different operational states (normal operation, warning state, stop execution) based on the current distance measurement. This dynamic approach optimizes both safety and operational efficiency.
2Device complexity
If a single threshold distance is used for stopping, then the system complexity is reduced, but the ability to provide progressive warning and controlled stopping is worsened
Solution Approach 1:
The single threshold distance is segmented into multiple threshold levels: a first threshold distance that triggers warning signals and a second threshold distance that triggers the actual stop. This segmentation divides the stopping process into distinct phases (warning phase and execution phase), allowing the system to provide progressive warning while maintaining relatively simple hardware architecture. The controller evaluates distance against multiple predefined thresholds rather than requiring complex continuous control algorithms.
Solution Approach 2:
The system employs periodic evaluation of the distance threshold conditions, continuously monitoring the distance between the elevator car and counterweight and periodically determining whether to issue warnings or execute stops based on predefined threshold criteria. This periodic threshold evaluation approach provides structured, predictable warning and stopping behavior without requiring complex real-time control algorithms, balancing simplicity with operational effectiveness.
3Reliability
If the brake is applied immediately when the threshold distance is reached, then the response time is reduced and safety is improved, but the operational smoothness and operator awareness are worsened due to sudden stops
Solution Approach 1:
The system issues preliminary warning signals (audible and visual) before executing the actual stop command. When the elevator car first reaches the first threshold distance, the system activates warning signals to alert the operator, providing advance notice without immediately applying the brake. Only when the car reaches the second, closer threshold distance does the system execute the stop command. This preliminary warning phase maintains safety response time while significantly improving operational smoothness and operator awareness.
Solution Approach 2:
The system dynamically transitions through different operational states based on distance thresholds: normal operation mode, warning mode (with audible/visual signals), and stop execution mode. This dynamic state transition provides a graduated response that adapts to the urgency of the situation, allowing smooth operation during warning phases while ensuring prompt stopping when necessary, thereby balancing safety response time with operational smoothness.
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 effectively prevents contact between the elevator car and counterweight by implementing controlled deceleration and audible alerts, ensuring mechanic safety and preventing potential hazards.
Implementation Method 1
a range finding sensor, operationally coupled to the warning system controller, and mounted to one of the elevator car, the counterweight and the hoistway wall
Data Source
AI summary
An elevator system having: a hoistway; an elevator car movable within the hoistway; a controller operationally coupled to the elevator car; a counterweight coupled to the elevator car and movable within the hoistway; and an approaching-hazard-warning-system that has: a warning system controller; a range finding sensor, operationally coupled to the warning system controller, and mounted to one of the elevator car, the counterweight and the hoistway wall, wherein, while operating in an inspection mode, the warning system controller is configured to receive sensor data from the range finding sensor, detect when a distance between the elevator car and the counterweight is less than a stop distance while the elevator car and the counterweight are moving toward each other, and execute a first responsive action including one or more of slowing the elevator car by communicating with the car controller, stopping the elevator car and sounding a first audible alert.