Fiber Optic Pull Cable Safety Switch for Trapped Worker Shutdown
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Solution Overview
Problem
In dangerous, enclosed structures, workers often get trapped and accidents occur due to unawareness of their presence during operations, leading to fatalities, especially in noisy environments with multiple entry points, where calls for help may not be heard.
Innovation Solution
The implementation of an illuminated pull cable connected to a fiber optic safety switch system that allows a trapped person to stop hazardous operations by breaking a light circuit, which disrupts the power supply to the equipment, and includes redundant light sources and modulated signals for enhanced safety and integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional safety systems using audible alarms and electrical cables are used in noisy enclosed environments, then the system can detect trapped persons, but the trapped person cannot be heard calling for help and may not respond to electrical signals
Solution Approach 1:
The patent replaces traditional electrical safety systems with an optical fiber-based system. The illuminated optical cable provides visual signals that are not interfered with by noisy environments, and the optical fiber transmission is immune to electromagnetic interference, thereby resolving the contradiction between safety reliability and noise environment interference
Solution Approach 2:
The patent uses different colored lights (red, yellow, green) to indicate different safety states and trap conditions. The trapped person can visually perceive these color changes even in noisy environments where audible alarms are ineffective, improving the reliability of safety communication
2Ease of operation
If multiple doors are provided for human ingress and egress in enclosed structures, then accessibility is improved, but trapped persons may be mistakenly assumed to have exited through a different door
Solution Approach 1:
The patent divides the enclosed structure into multiple zones, each with its own optical safety system and illuminated cable. Each door is associated with specific optical fibers that can independently detect whether a person is trapped in particular zones, allowing accurate determination of trapped person location even when multiple doors are present
Solution Approach 2:
The patent implements a feedback mechanism where optical sensors continuously monitor the presence of persons in each zone and provide real-time information to the control system. This feedback enables the system to accurately determine whether a person is trapped in a specific zone, preventing mistaken assumptions about their location or exit status
3Ease of operation
If the illuminated cable is made visible to trapped persons in dark environments, then the trapped person can activate the safety system, but the cable must be sufficiently bright which increases energy consumption
Solution Approach 1:
The patent uses LED light emitters that can dynamically adjust their brightness parameters. The LEDs can operate at high brightness when a trapped person is detected to ensure visibility and activation capability, then reduce to lower brightness levels during normal operation to minimize energy consumption, thus resolving the contradiction between ease of operation and energy usage
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
This system effectively prevents accidents by ensuring that if a trapped person can see and interact with the illuminated cable, it will stop the operating equipment, alerting others and potentially unlocking doors, thereby preventing fatalities in confined spaces like autoclaves and grain silos.
Implementation Method 1
a fiber optic bundle with at least one section of illuminated cable which emits visible light and which also comprises optical cables which carry at least one and preferably a plurality of different control signals. The signal light(s) follow an optical circuit through the fiber optic bundle from the signal light transmitter(s) to the signal light receiver(s)
Implementation Method 2
The signal light can be modulated and/or reflected back through the same length of fiber optic cable or can travel in a continuous path without reflection. If the signal light receivers receive the correct predetermined signal light, they generate electrical pulses
Data Source
AI summary
Safety systems for operating equipment have a source of visible light, a first signal light transmitter, a first signal light receiver, preferably a second signal light transmitter and second signal light receiver. A fiber optic bundle with at least one section of illuminated cable emits the visible light and carries the signal light. The signal light follows an optical circuit through the fiber optic bundle from the signal light transmitters to the signal light receivers. The signal light receivers are connected to suitable controls of the system such that if a predetermined light signal is not received by the signal light receiver(s), the operating equipment will stop and/or alarms will be generated. The fiber optic bundle is connected to optical pull switches which interrupt the light circuit if a person applies a predetermined pull force to the optical fiber bundle.