Vented Propane Combustion Chamber for Insect Traps

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Solution Overview

Problem

Cordless insect trapping devices with tubular combustion chambers often experience a self-amplifying standing wave, leading to an audible 'howling' noise due to low flow rate, high heat, and unit geometry, which interferes with optimal operating temperature and user comfort.

Innovation Solution

A vented combustion chamber is created by drilling a hole in the side of the chamber or using the existing through-hole for the spark ignitor electrode assembly, reversing its mounting order with the thermistor assembly, or using a mounting flange assembly with a spacer to form a gap, which prevents the formation of standing waves by allowing gas to escape to the atmosphere.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a tubular combustion chamber is used to generate carbon dioxide flow for attracting insects, then the device can effectively trap flying insects, but a self-amplifying standing wave is created causing audible howling noise that interferes with optimal operating temperature and user comfort

Engineering Contradiction:

Improveinsect trapping effectivenessVSAvoidhowling noise

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the harmful standing wave phenomenon from the combustion chamber by introducing a vent hole that allows gas to escape, thereby eliminating the resonance condition that causes howling noise while preserving the insect-attracting carbon dioxide generation function

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the potentially harmful standing wave energy into a beneficial outcome by using the vent to release pressure buildup, transforming the resonance problem into a controlled gas release mechanism that prevents howling while maintaining combustion efficiency

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Object-affected harmful factors

If the combustion chamber is vented to prevent standing wave formation, then howling noise is eliminated, but the chamber structure must be modified

Engineering Contradiction:

Improvehowling noise eliminationVSAvoidchamber structure modification

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the vent hole creation with the existing spark ignitor electrode assembly mounting location, using the same through-hole in the combustion chamber wall for both purposes, thereby eliminating the need for separate vent openings and reducing structural complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The through-hole in the combustion chamber wall serves multiple functions: it provides the mounting location for the spark ignitor electrode assembly and simultaneously acts as the vent hole for releasing gas pressure and preventing standing wave formation, thereby achieving noise elimination without additional structural modifications

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 venting of the combustion chamber reduces or eliminates the resonance cycle and acoustic howling, allowing the device to reach optimal operating temperature without disrupting combustion or increasing heat leakage.

Implementation Method 1

a combustion chamber to generate a flow of carbon dioxide for attracting mosquitos and other flying insects toward the trap

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 2

gas inside the chamber, which is at a higher-than-atmospheric pressure, to exit the chamber to the outside of the device

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentUS9949471B2Vented propane combustion chamber for insect attractant engine

Publication Date: 2018.04.24 WOODSTREAM CORP

AI summary

A vented combustion chamber for an insect attractant engine is provided for a flying insect trapping device of the type that relies upon combustion of a fuel to generate a flow of carbon dioxide to attract flying insects. The combustion chamber, which is generally tubular and horizontally oriented in operation, is vented through a hole formed in one side of the chamber wall that extends from the outer surface of the chamber into the interior thereof. During operation of the device, this through-hole allows gas inside the chamber to be vented to the outside, changing the effective length of the combustion chamber for the purposes of wave generation is changed so that creation of a resonance cycle or standing wave, and the resulting acoustic phenomenon of howling, is prevented.