Fire Detector VOC Sensitivity Adjustment

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Solution Overview

Problem

Fire detection systems in dirty environments, such as warehouses and factories, often experience false alarms due to the presence of particles other than smoke, leading to disruptions and costs, as they are not effectively differentiated from actual fire smoke.

Innovation Solution

A fire detector equipped with both a smoke sensor and a volatile organic compound (VOC) sensor that adjusts its smoke sensitivity based on VOC concentrations, using multiple thresholds to differentiate between actual smoke and non-combusted fuel emissions, thereby reducing false alarms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If smoke sensitivity is increased to improve fire detection effectiveness, then fire detection capability is improved, but false alarm rate increases due to non-fire particles

Engineering Contradiction:
Improvefire detection capabilityVSAvoidfalse alarm rate
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces VOC sensors as intermediary detectors that detect volatile organic compounds emitted by both fires and non-fire sources. By using VOC concentration as a mediator parameter, the system can distinguish between fire smoke and non-fire particles through the ratio relationship between smoke particle concentration and VOC concentration, thereby reducing false alarms while maintaining fire detection capability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent dynamically adjusts the smoke alarm threshold parameter based on detected VOC concentration levels. When VOC concentration is high (indicating potential non-fire sources), the smoke alarm threshold is raised to prevent false alarms. When VOC concentration is low, the threshold returns to normal sensitivity levels, ensuring the system adapts its detection parameters to current environmental conditions

Inventive Principle:
Principle #35Parameter changes

2Object-generated harmful factors

If smoke sensitivity is decreased to reduce false alarms, then false alarm rate is reduced, but fire detection effectiveness deteriorates

Engineering Contradiction:
Improvefalse alarm rateVSAvoidfire detection capability
Core Design Contradiction:
Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent implements dynamic adjustment of smoke sensitivity threshold based on real-time VOC concentration measurements. The threshold is not fixed but varies dynamically according to environmental conditions: it decreases when VOC levels indicate non-fire sources are present, and returns to high sensitivity when VOC levels suggest normal conditions, thus maintaining optimal fire detection capability across different scenarios

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system uses feedback from VOC sensor measurements to continuously adjust the smoke alarm threshold. The VOC concentration serves as feedback information about the environmental context, allowing the system to intelligently modulate its smoke detection sensitivity in response to detected conditions, preventing both false alarms and missed detections

Inventive Principle:
Principle #23Feedback

3Measurement precision

If multiple sensors are added to differentiate smoke types, then detection accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvesmoke differentiation accuracyVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the existing smoke sensor serve multiple functions: it detects both fire smoke particles and non-fire particles. By combining this universal smoke detection capability with VOC sensor data, the system achieves smoke differentiation without requiring separate specialized sensors for each smoke type, thus improving measurement precision while limiting the increase in device complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 reduces false alarms in dirty environments while maintaining sensitivity to actual fire smoke, ensuring timely and accurate fire detection and response.

Implementation Method 1

detection of smoke particles suspended in the air, for example by detecting light scattered caused by the smoke particles

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 2

a large numbers of molecules of these compounds evaporate or sublimate from the liquid or solid form of the compound and enter the surrounding air

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP4009296B1Fire detection for dirty environments
Publication Date: 2024.11.20 CARRIER CORP
  • EP4009296B1 patent drawingFigure 1

AI summary

A fire detector for monitoring an environment and a method of operating a fire detector comprising a smoke sensor and a volatile organic compound, VOC, sensor is described. A fire detector 10 for monitoring an environment 20 comprises a smoke sensor 12 and a volatile organic compound, VOC, sensor 14, wherein the fire detector 10 is configured to adjust a smoke sensitivity of the fire detector 10 based on a VOC concentration detected by the VOC sensor 14. The smoke sensitivity is decreased when increased VOC concentrations are detected.