Grill Gas Shutoff Circuit Using Flame Signal Change Detection
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Solution Overview
Problem
Existing grill safety systems face reliability issues due to wear, degradation, or contamination of flame sensors, leading to inaccurate detection of flame presence, which can result in unsafe gas flow conditions.
Innovation Solution
A safety shutoff system that uses a control circuit and flame sensor to monitor changes in a detection signal rather than relying on absolute values, ensuring reliable detection of flame presence or absence, and automatically shutting off gas flow if no flame is detected, thereby preventing gas leaks and ensuring safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flame sensor is used to detect flame presence, then safety monitoring is enabled, but the sensor degrades and contaminates over time causing detection accuracy to deteriorate
Solution Approach 1:
The patent changes the measurement parameter from absolute flame detection to differential signal change detection. By monitoring changes in the flame detection signal over time rather than relying on absolute signal thresholds, the system becomes insensitive to sensor degradation and contamination that cause gradual signal drift, thereby maintaining detection accuracy despite sensor aging
Solution Approach 2:
The system continuously monitors the flame detection signal and compares it against reference values or previous measurements. This feedback mechanism allows the system to adapt to gradual sensor degradation by detecting deviations from normal signal patterns, enabling reliable flame presence determination even as the sensor characteristics change over time
2Reliability
If the safety shutoff system continuously monitors flame detection, then safety is improved, but false shutdowns may occur due to sensor degradation
Solution Approach 1:
The patent transforms the detection approach from threshold-based absolute measurement to change-based differential measurement. By detecting signal changes rather than absolute signal levels, the system avoids false shutdowns caused by sensor degradation that shifts absolute signal levels but preserves signal change patterns during actual flame loss events
Data Source
AI summary
A system for igniting a grill can include a solenoid valve, a flame rectification sensor, an igniter, and a control circuit connected to the solenoid valve and the flame rectification sensor. The solenoid valve controls flow of gas to the grill's burner and includes a switch that closes when a handle connected to the switch opens the solenoid valve. The control circuit sends current to the solenoid valve when the switch is closed to hold the solenoid valve open. After the switch closes, the igniter is ignited. After ignition, the control circuit monitors the presence of a flame with a flame rectification sensor. If no flame is detected after a certain amount of time, the control circuit stops sending current to the solenoid valve to close the solenoid valve.