Elevator Hoistway Door Safety Switch and Actuator
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Solution Overview
Problem
Elevator systems with low pits pose a safety risk for mechanics during inspection, maintenance, or repair, as existing solutions require significant additional components and wiring to prevent the elevator car from moving, which is not always feasible or efficient.
Innovation Solution
An elevator system equipped with a hoistway door safety switch connected to an electronic safety actuator that activates a safety mechanism to stop the elevator car when the door is open, ensuring the car does not move into dangerous positions, thereby enhancing safety with minimal structural effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a movable prop is provided within the pit to create an emergency rescue space, then the safety of persons in the pit is improved, but the device complexity and wiring effort increase significantly
Solution Approach 1:
The patent introduces an intermediary device (blockade member) that can be positioned in the pit to prevent the car from moving into dangerous positions. This intermediary physical barrier serves as a mediator between the safety requirement and the existing elevator components, avoiding the need for complex movable prop systems with extensive wiring.
Solution Approach 2:
The patent extracts the safety function from the complex movable prop system and implements it through a simpler blockade member that can be manually positioned. This separates the safety function from the need for complex actuation mechanisms, relay circuitry, and wiring, achieving safety with minimal additional components.
2Reliability
If the elevator car is prevented from moving while a mechanic is in the pit, then the safety of the mechanic is improved, but the productivity and ease of operation deteriorate due to inability to move the car for necessary inspections and repairs
Solution Approach 1:
The patent implements a dynamic safety system where the blockade member can be positioned at different locations in the pit. When a mechanic needs to work in the pit, the blockade is placed to prevent car movement into dangerous zones. When maintenance requires car movement, the blockade can be repositioned or removed, allowing the car to move freely. This dynamic adjustment resolves the contradiction between safety and operational flexibility.
Solution Approach 2:
The system changes the parameter of car mobility dynamically - the car is constrained when the blockade is in position, but can move when the blockade is repositioned. This parameter change allows the system to adapt between safety mode (car constrained) and maintenance mode (car movable), resolving the contradiction between these two operational requirements.
3Reliability
If the safety is activated immediately when the door is open, then the safety response is improved, but the productivity deteriorates due to unnecessary stops when the car is already at a safe position
Solution Approach 1:
The patent applies local quality by positioning the blockade member at specific locations in the pit corresponding to dangerous zones. The safety system doesn't uniformly prevent all car movement, but rather constrains the car only when it would enter dangerous areas identified by the door switch. This localized safety approach prevents unnecessary stops when the car is already at safe positions, resolving the contradiction between safety response and operational efficiency.
Solution Approach 2:
The door switch is positioned to detect door opening in advance, allowing the system to prepare for potential safety activation. However, the actual safety action (blockade engagement) only occurs when the car approaches dangerous zones, not immediately upon door opening. This preliminary detection combined with conditional activation prevents unnecessary stops while maintaining safety readiness.
Data Source
AI summary
An elevator system (1) comprises: a hoistway (4) extending between a plurality of landings (8, 9); at least one hoistway door (10, 11) allowing access to the hoistway (4); an elevator car (6), which is configured to move along the hoistway (4); at least one safety (16), which is attached to the elevator car (6) and configured to stop any movement of the elevator car (6) when activated; an electronic safety actuator (18), which is configured to activate and deactivate the at least one safety (16); and a door safety switch (20), which is configured to monitor the at least one hoistway door (10, 11) and which is connected with the electronic safety actuator in order to allow activating the at least one safety (16), if the door safety switch (20) detects that the at least one hoistway door (10, 11) is not closed.