Heatable Gas Sensor Fire Detector with Temperature Cycling
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Solution Overview
Problem
Conventional fire detectors often generate false alarms in environments like kitchens due to hot steam and dense vapor, and may not effectively detect fires in chemical laboratories or production areas, highlighting a need for improved fire detection methods that utilize additional or alternate parameters beyond smoke, heat, or flame.
Innovation Solution
A fire detector incorporating a heatable gas sensor that cycles through various temperature ranges, with sampled outputs processed by pattern recognition circuitry to determine fire conditions, using commercially available micromachined sensors and control circuits for data acquisition and processing, potentially combined with additional smoke or thermal sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional smoke detectors are used in kitchens, then they can detect fire aerosols, but they generate false alarms due to hot steam and dense vapor
Solution Approach 1:
The gas sensor cycles through multiple temperature ranges (e.g., 200°C, 400°C, 600°C, 800°C) to detect gases at different thermal states. Fire produces characteristic gas signatures at specific temperatures that differ from cooking vapors, enabling discrimination between fire and non-fire conditions through temperature-dependent gas analysis
Solution Approach 2:
The sensor operates in periodic temperature cycling modes, alternating between heating and measurement phases. This periodic temperature variation allows the system to capture gas composition changes over time at different temperatures, creating a thermal signature profile that distinguishes fire from kitchen vapors
2Object-generated harmful factors
If thermal detectors are used in kitchens, then they can avoid false alarms from steam, but they cannot detect fires when temperature rises exceed 50°C from cooking
Solution Approach 1:
Instead of relying solely on temperature threshold detection, the system analyzes gas composition parameters at multiple temperature levels. The gas sensor detects characteristic combustion gases (CO, CO2, hydrocarbons) that are produced in fire but not in normal cooking, even when temperature rises are similar. This shifts the detection parameter from temperature magnitude to gas composition signature
Solution Approach 2:
The gas sensor acts as an intermediary between the thermal environment and the detection system. It samples and analyzes the chemical composition of gases in the thermal plume, providing a mediator parameter (gas signature) that distinguishes fire from cooking even when direct temperature measurement cannot differentiate between the two conditions
3Measurement precision
If a gas sensor cycles through multiple temperature ranges, then fire detection accuracy improves, but power consumption increases
Solution Approach 1:
The sensor cycles through temperature ranges periodically rather than continuously, with duty cycles that balance measurement accuracy and power consumption. The system can use longer measurement intervals, lower heating powers during cycles, or skip certain temperature levels based on environmental conditions, reducing average power while maintaining detection capability
Solution Approach 2:
The temperature cycling profile is dynamically adjustable based on detected conditions. The system can modify cycle frequency, temperature range, and heating duration in response to ambient conditions, alarm history, and detected gas levels, optimizing the balance between measurement precision and power consumption in real-time
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 approach effectively discriminates between fire and non-fire conditions in challenging environments, reducing false alarms and power consumption, while maintaining the ability to detect European Standard EN 54-compliant fires, even after extended operation.
Implementation Method 1
A fire detector which embodies the invention incorporates a heatable gas sensor
Implementation Method 2
one or more outputs at each temperature range acquired can be coupled in parallel to pattern recognition circuitry
Data Source
AI summary
A fire detector incorporates a heatable gas sensor. The sensor is cycled through a plurality of different operating temperature ranges, and one or more outputs at each temperature range are acquired. A plurality of acquired outputs, corresponding to the plurality of temperature ranges, can be coupled in parallel to pattern recognition circuitry. The pattern recognition circuitry can process the acquired outputs and make a determination that the processed data samples are indicative of the presence of a fire condition.