Single-element pellistor gas detector with environmental compensation

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Solution Overview

Problem

Current flammable gas detectors, particularly those using platinum wire-based pellistor sensors, face issues with high power consumption and sensitivity to environmental variations, leading to reduced battery life and inaccurate readings.

Innovation Solution

A low-cost batch packaging technology is employed, featuring a single-element pellistor, a temperature sensor, and a relative humidity sensor, where the sensors are isolated to minimize the impact of environmental factors, and low-power consumption components are used to reduce heat transfer and airflow, thereby enhancing accuracy and extending battery life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If dual-pellistor system with poisoned pellistor is used for compensation, then measurement precision is improved, but use of energy deteriorates due to heating both pellistors to 500°C

Engineering Contradiction:
Improvegas detection accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The invention extracts the compensation function from the dual-pellistor system and implements it separately using a temperature sensor and humidity sensor. This allows the gas detector to use only a single pellistor for gas detection, eliminating the need to heat a second poisoned pellistor while maintaining compensation capabilities through the dedicated environmental sensors.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The temperature sensor and humidity sensor serve multiple functions: they compensate for environmental variations affecting gas detection, and they enable the system to operate with reduced power consumption compared to heating two pellistors. This multi-functional approach replaces the specialized poisoned pellistor compensation method.

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

2Reliability

If platinum wire-based pellistor is used for gas detection, then reliability is improved, but use of energy deteriorates due to continuous heating requirement

Engineering Contradiction:
Improvesensor stabilityVSAvoidbattery life
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The invention separates the heating function from the detection function by using a dedicated temperature sensor instead of relying on the pellistor's temperature measurement capability. This allows the pellistor to be heated only when necessary for detection, rather than continuously maintaining temperature for both detection and measurement purposes.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system dynamically adjusts the heating parameters of the pellistor based on actual detection needs and environmental conditions measured by the temperature and humidity sensors. This optimized heating control reduces overall power consumption while maintaining detection reliability.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If temperature sensor and humidity sensor are added for compensation, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improveenvironmental compensation accuracyVSAvoidsensor system components
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of using a complex poisoned pellistor system to infer environmental conditions, the invention uses simple, dedicated temperature and humidity sensors that directly measure environmental parameters. These sensors provide accurate compensation data without the complexity of maintaining a second functional pellistor.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The invention replaces the mechanical/chemical compensation mechanism (poisoned pellistor) with electronic sensing (temperature and humidity sensors). This substitution simplifies the system by using electronic measurements and processing rather than complex mechanical or chemical compensation structures.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 results in flammable gas detectors that are less sensitive to internal and external interferences, providing improved accuracy and reduced power consumption, thus extending the battery life of portable detectors.

Implementation Method 1

The platinum wire resistance-based pellistor flammable gas sensors may operate by allowing or causing the flammable gas to combust on the surface of a catalyst and measuring the generated heat

Methodology Applied
Scientific EffectCombustion: Combustion

Implementation Method 2

To promote combustion, the bead-like catalyst is heated by electric current flowing through the resistive platinum wire

Methodology Applied
Scientific EffectCatalysis: Catalysis

Implementation Method 3

the bead-like catalyst is heated by electric current flowing through the resistive platinum wire

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 4

the resistance of the platinum is measured before and after combustion, and the temperature coefficient of platinum resistance is used to calculate the heat generated by combustion of flammable gas

Methodology Applied
Scientific EffectTemperature coefficient of resistance: Thermo-resistive Effect

Implementation Method 5

To evaluate the effect of atmospheric variations on the combustion-generated heat, and thus to correctly measure the flammable gas concentration, a temperature sensor and a relative humidity sensor may be used

Methodology Applied
Scientific EffectHygroscopy: Hygrometer

Data Source

PatentEP2806266B1Single element pellistor insensitive to internal and external interferences
Publication Date: 2017.06.14 HONEYWELL INTERNATIONAL INC
  • EP2806266B1 patent drawingFigure 1
  • EP2806266B1 patent drawingFigure 2
  • EP2806266B1 patent drawingFigure 3

AI summary

The present disclosure relates to a low-cost, batch packaging technology for flammable gas detectors, where each flammable gas detector includes a single-element pellistor (122), a temperature sensor (124), and a relative humidity sensor (126). These flammable gas detectors are less sensitive to internal and external interferences than current pellistor-based gas sensors, and are able to provide improved sensor accuracy while reducing electric power consumption.