Controller Adjusts Excess Air Ratio for Combustion Ignition
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Solution Overview
Problem
Existing combustion apparatuses face issues with ignition errors due to misjudged excess air ratios, leading to potential explosive ignition and poor combustion, especially when air remains in the gas supply passage, causing the controller to either over- or under-reduce the excess air ratio during re-ignition attempts.
Innovation Solution
The combustion apparatus employs a controller that adjusts the excess air ratio by setting initial and lower-limit values based on accumulated combustion time, using estimated values correlated with fan rotational speed and proportional valve current, and performs re-ignition operations by increasing fuel gas volume or decreasing combustion air volume to ensure proper ignition, while also counting re-ignition attempts to detect ignition errors and adjust the air ratio accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the controller stepwise reduces the excess air ratio from the initial value when ignition fails, then the burner can ignite in cases where air remains in the gas supply passage, but the excess air ratio may become excessively low causing explosive ignition or poor combustion
Solution Approach 1:
The controller dynamically adjusts the excess air ratio parameter based on the number of re-ignition attempts. For the first re-ignition attempt, it uses a first excess air ratio (higher safety margin), and for subsequent attempts, it uses a second excess air ratio (lower for better ignition). This parameter change strategy resolves the contradiction by adapting the air ratio to the specific ignition context.
Solution Approach 2:
The system transitions from a static excess air ratio setting to a dynamic adjustment mechanism that changes based on ignition history. The controller monitors ignition success/failure and automatically modifies the excess air ratio accordingly, making the system adaptive rather than fixed, thereby preventing both failed ignition and dangerous conditions.
2Ease of operation
If the controller uses a fixed initial excess air ratio value, then the system is simple to operate, but it cannot adapt to different operational states leading to misjudgment of air ratios
Solution Approach 1:
The controller performs self-adjustment by automatically selecting appropriate excess air ratio values based on its internal state (number of re-ignition attempts). No external intervention or complex user input is needed - the system serves itself by monitoring its own operation and adapting parameters accordingly, maintaining simplicity while achieving adaptability.
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 solution ensures easier ignition and prevents malfunctions like explosive ignition and carbon monoxide generation by accurately adjusting the excess air ratio during re-ignition, maintaining efficient combustion and safety by adapting to different operational states and reducing the risk of misjudging air ratios.
Implementation Method 1
an igniter for igniting the burner
Implementation Method 2
a fan for supplying the burner with combustion air
Implementation Method 3
a proportional valve installed in the gas supply passage
Implementation Method 4
a burner disposed in a combustion chamber and for combusting a mixture gas of combustion air and a fuel gas
Data Source
AI summary
A controller memorizes an accumulated combustion time by accumulating combustion time of a burner, and is set in a first lower-limit and a second lower-limit higher than the first lower-limit as a lower-limit lower than an initial value of an excess air ratio when reducing an excess air limit of a mixture gas of combustion air and a fuel gas, and the former is the lower-limit in case the accumulated combustion time is under a predetermined set time and the latter is the one in case the accumulated combustion time is the predetermined set time and over.