Elevator Safety Chain Using Series Non-Contact Switches
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Solution Overview
Problem
Conventional elevator systems relying on electrical contacts for door safety switches are prone to wear and require frequent maintenance, while complex non-contact switch arrangements offer reliability but increased complexity in wiring and monitoring.
Innovation Solution
The implementation of a series-connected first and second non-contact switch configuration within each set, where the monitoring device measures electrical properties to detect open hoistway doors, providing redundancy and reducing complexity by monitoring only two electrical paths, with optional bypass impedances for enhanced diagnostic capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrical contacts are used for safety switches, then reliability is improved, but maintenance requirements increase due to wear and dirt accumulation
Solution Approach 1:
The patent replaces mechanical electrical contacts with non-contact switches (such as optical, magnetic, or capacitive sensors) that detect door position without physical contact. This eliminates wear and contamination issues inherent in mechanical contact systems, thereby maintaining reliability while reducing maintenance requirements.
2Reliability
If multiple redundant non-contact switches are used, then reliability is improved, but device complexity increases due to complex wiring and monitoring hardware
Solution Approach 1:
The patent combines multiple non-contact switches into a unified monitoring system where the switches are connected in parallel between a common voltage line and a common signal line. This merging approach allows the system to monitor multiple door positions while requiring monitoring of only two electrical paths (voltage line and signal line), significantly reducing wiring and monitoring complexity compared to individual monitoring of each switch.
Solution Approach 2:
The common voltage line and common signal line serve multiple functions simultaneously: they provide power to all non-contact switches, collect status signals from all switches, and enable centralized monitoring of the entire door safety system through just two electrical paths, thereby reducing overall system complexity.
Data Source
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AI summary
An elevator system (2) is provided which comprises a plurality of hoistway doors (10a, 10b, 10c), a corresponding plurality of sets of non-contact switches (12a, 12b, 12c), each set arranged to detect when a respective hoistway door (10a, 10b, 10c) is open, and a monitoring device (26). Each set of non-contact switches (12a, 12b, 12c) comprises a first non-contact switch (14a, 14b, 14c) arranged to open when the respective hoistway door (10a, 10b, 10c) is open and a second non-contact switch (16a, 16b, 16c) arranged to open when the respective hoistway door (10a, 10b, 10c) is open. The first non-contact switches (14a, 14b, 14c) of the plurality of sets are connected in series to form a first electrical path (22) and the second non-contact switches (16a, 16b, 16c) of the plurality of sets are connected in series to form a second electrical path (24). The monitoring device (26) is arranged to measure an electrical property of the first electrical path (22) and an electrical property of the second electrical path (24) to detect when a hoistway door (10, 10b, 10c) is open.