Carbon Monoxide Sensor Trailing Window Average Logic
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Solution Overview
Problem
Internal combustion engines used in portable generators often produce carbon monoxide (CO) that can accumulate in enclosed spaces, posing a safety risk, as existing systems struggle to accurately differentiate between transient CO spikes and sustained elevated levels, leading to potential nuisance shutdowns or failure to detect hazardous CO concentrations.
Innovation Solution
A CO detection system that includes a CO sensor unit with a controller capable of calculating a trailing window average (TWA) of CO levels over consecutive sampling loops, combined with runtime monitoring, to determine whether to initiate a shutdown based on predetermined thresholds, adjusting sensitivity based on the engine's runtime and environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the CO sensor uses a fixed threshold for shutdown detection, then the shutdown response is simple and fast, but it causes nuisance shutdowns due to transient CO spikes and cannot accurately distinguish between temporary fluctuations and sustained hazardous levels
Solution Approach 1:
The patent applies dynamics by making the shutdown threshold dynamic rather than fixed. The threshold adapts based on the engine runtime state: during warm-up period (0-12 minutes) a first threshold is used, and after the warm-up period a second threshold is used. This dynamic adjustment allows the system to accommodate transient CO spikes during engine startup while maintaining strict safety thresholds during normal operation, thereby improving detection accuracy without requiring overly complex real-time analysis algorithms.
Solution Approach 2:
The patent applies preliminary action by pre-defining runtime-based threshold values in the controller. The system预先 sets different CO thresholds based on expected runtime phases (warm-up vs. normal operation), so that when transient spikes occur during startup, the appropriate higher threshold is already in place, preventing nuisance shutdowns before they happen. This eliminates the need for complex real-time differentiation logic while maintaining accurate hazard detection.
2Reliability
If the CO sensor implements strict shutdown criteria to ensure safety, then hazardous CO accumulation is reliably detected, but transient CO spikes during normal operation cause unnecessary shutdowns
Solution Approach 1:
The patent applies dynamics by implementing runtime-dependent threshold adjustment. During the warm-up period (0-12 minutes), when transient CO spikes are normal, a higher first threshold is applied. After the warm-up period, when the engine should operate steadily, a stricter second threshold is applied. This dynamic thresholding ensures safety reliability during normal operation while allowing continuous operation during startup by accommodating expected transient behavior.
Solution Approach 2:
The patent applies preliminary action by pre-establishing the runtime threshold adaptation logic. The controller is programmed to automatically switch between thresholds based on engine runtime, so that the appropriate threshold is already in place before transient spikes occur during warm-up. This preliminary configuration prevents unnecessary shutdowns during normal startup operations while maintaining strict safety monitoring during sustained operation.
3Speed
If the CO sensor monitors CO levels continuously with high sensitivity, then hazardous conditions are detected quickly, but the system cannot differentiate between transient spikes and sustained elevated levels
Solution Approach 1:
The patent applies preliminary action by pre-defining the warm-up period duration (12 minutes) and the corresponding higher threshold for this period. When CO levels are monitored during this pre-defined window, the system automatically applies the appropriate higher threshold, enabling quick detection of hazards while tolerating expected transient spikes. This preliminary time-based configuration provides both fast hazard response and accurate transient discrimination without requiring complex real-time pattern recognition.
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
Effectively reduces nuisance shutdowns while ensuring safety by accurately distinguishing between transient CO spikes and sustained hazardous levels, thereby protecting against CO accumulation in enclosed spaces.
Implementation Method 1
a CO sensing circuit configured to detect a level of CO
Data Source
AI summary
An engine assembly includes an internal combustion engine and a carbon monoxide (CO) sensor unit. The CO sensor unit includes a CO sensor controller including a CO sensing circuit configured to detect a level of CO and a shutdown circuit. The shutdown circuit is configured to receive a detected level of CO and calculate a trailing window average of the detected level of CO. The trailing window average includes an average of the detected level of CO over a predetermined sampling window. The shutdown circuit is further configured to determine whether to initiate a shutdown of the internal combustion engine based on at least the calculated trailing window average and a predetermined trailing window average threshold and initiate the shutdown of the internal combustion engine based on determining that the trailing window average exceeds the predetermined trailing window average threshold.