Exhaust Sampling Controller for Intermittent Engine Operation
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Solution Overview
Problem
Conventional exhaust sampling systems, such as CVS and BMD, are not well-suited for intermittently operating internal combustion engines, like those in hybrid-electric vehicles, as they are designed for continuous engine operation, leading to inefficiencies and incomplete sample collection during sampling periods.
Innovation Solution
An exhaust sampling system with a controller that manages the flow of exhaust gas to collection bags based on the engine's ON time, allowing selective supply and bypass of exhaust gas, and using make-up air or fill gas to ensure sufficient sample volume for analysis, optimizing the sampling process for intermittent engine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional CVS or BMD systems are used for intermittently operating engines, then the sampling system can collect diluted exhaust gas, but the sample collection becomes incomplete during sampling periods when the engine is not running
Solution Approach 1:
The controller determines the engine's ON time during the sampling period and calculates the required extraction rate in advance. Make-up air or fill gas is pre-prepared to supplement the sample volume if the engine operates intermittently, ensuring the minimum required sample volume is achieved before analysis begins.
Solution Approach 2:
The system dynamically adjusts the extraction rate of the sample probe based on the determined engine ON time. The controller modifies flow parameters in real-time to optimize sample collection during intermittent operation, and supplements with make-up air or fill gas to maintain the required sample volume and dilution ratio.
2Quantity of substance
If the sample probe continuously extracts exhaust gas during the entire sampling period, then the sample volume is sufficient, but the dilution ratio increases when the engine is not running
Solution Approach 1:
The sample probe operates periodically rather than continuously, extracting exhaust gas only during periods when the engine is running. The controller activates the sample probe based on detected engine ON/OFF cycles, preventing unnecessary extraction during engine inactivity and thereby maintaining an optimal dilution ratio while still accumulating sufficient sample volume over the sampling period.
Solution Approach 2:
The controller determines the engine's total ON time in advance and pre-calculates the required extraction rate to achieve the desired sample volume and dilution ratio. Make-up air or fill gas is prepared in advance to supplement the sample if the engine's actual operation falls short of the predicted ON time, ensuring both sufficient volume and acceptable dilution ratio.
3Quantity of substance
If the extraction rate is increased to ensure sufficient sample volume for intermittent operation, then the sample volume is adequate, but the system complexity increases
Solution Approach 1:
The controller continuously monitors the engine's operation state and the sampling progress, comparing actual sample volume against the required minimum. Based on this feedback, the controller dynamically adjusts the extraction rate and determines when to introduce make-up air or fill gas, creating a closed-loop control system that automatically optimizes sample collection without requiring complex manual intervention.
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 system ensures accurate and efficient collection of exhaust samples by adjusting the extraction rate and supplementing with make-up air or fill gas, maintaining a low dilution ratio and achieving the minimum required sample volume for analysis, even during periods of engine inactivity.
Implementation Method 1
a first sample probe in fluid communication with the source of exhaust gas that selectively supplies the at least one collection bag with the exhaust gas
Data Source
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AI summary
An exhaust sampling system for an engine is provided. The exhaust sampling system may include a source of exhaust gas, an exhaust collection unit including at least one collection bag that selectively receives the exhaust gas, and a first sample probe in fluid communication with the source of exhaust gas that selectively supplies the at least one collection bag with the exhaust gas. The exhaust sampling system may also include a controller that permits flow of the exhaust gas from the first sample probe to the at least one collection bag in a first state and prevents flow of the exhaust gas from the first sample probe to the at least one collection bag in a second state. The controller may determine an extraction rate of the first sample probe based on an ON time of the engine during a sampling period.