Diesel Engine PM Emission Estimation Using Transient Correction
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Solution Overview
Problem
Conventional PM emission estimation devices inaccurately estimate PM emission amounts during transient engine operation conditions due to the lack of differentiation in correction factors between steady and transient states, and rely on potentially inaccurate air excess ratio measurements.
Innovation Solution
A PM emission estimation device that distinguishes between steady and transient operation conditions by analyzing changes in air excess ratio, using a first-order lag low-pass filter to remove noise and apply specific correction factors based on air excess ratio, engine speed, and oxygen concentration to accurately compute PM emission amounts during transient states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single correction factor is used for both steady and transient operation conditions, then the device complexity is reduced, but the measurement precision of PM emission amount deteriorates during transient conditions
Solution Approach 1:
The patent divides the correction factor system into two separate components: a base correction factor for steady operation conditions and an additional correction factor for transient operation conditions. This segmentation allows each correction factor to be optimized for its specific operating condition, improving overall measurement precision without excessive complexity increase.
Solution Approach 2:
The patent introduces a dynamic adjustment mechanism where the transient correction factor is applied conditionally based on detected transient operation states. The correction factor system transitions from static (single factor) to dynamic (conditional multi-factor), allowing the system to adapt to changing operating conditions and maintain precision during transients.
2Ease of manufacture
If air excess ratio is used to compute correction factor, then the computation is simplified, but the reliability of the correction factor deteriorates due to measurement inaccuracies
Solution Approach 1:
The patent introduces a transient state detection mechanism as an intermediary between the air excess ratio measurement and the correction factor computation. This intermediary filters out measurement noise and inaccuracies by detecting actual transient conditions, thereby improving the reliability of the correction factor while maintaining computational simplicity.
Solution Approach 2:
The patent implements a feedback mechanism where the transient state detection results are fed back into the correction factor computation process. This feedback loop allows the system to adjust the correction factor based on actual operating conditions rather than relying solely on potentially inaccurate air excess ratio measurements, thereby improving reliability.
3Productivity
If correction factor is applied continuously, then the PM emission amount is corrected for all conditions, but the manufacturing precision of the estimation deteriorates due to inappropriate corrections during steady state
Solution Approach 1:
The patent makes the correction factor application dynamic by conditioning it on detected transient operation states. Instead of continuous application, the correction is applied only when transients are detected, preventing inappropriate corrections during steady state and thereby improving estimation precision while maintaining productivity.
Solution Approach 2:
The patent applies different correction qualities to different operating conditions: full correction during transient states and no correction (or base correction only) during steady states. This local differentiation of correction quality ensures that corrections are applied only where needed, improving overall estimation precision without sacrificing productivity.
Data Source
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AI summary
Providing a PM emission amount estimation device for the diesel engine wherein the accuracy of the correction in correcting the basic level of the PM emission amount by use of the PM emission amount estimation map can be enhanced; and, the PM emission amount particularly during the transient state of the engine operation condition can be accurately computed so as to estimate, with high precision, the PM emission amount and the PM emission accumulated-amount (integrated amount) during the whole engine operation conditions including the transient state as well as the steady state. A PM emission amount estimation device for estimating the amount of the PM for estimating the amount of the PM that is emitted from a diesel engine and collected by a DPF provided in the exhaust gas passage of the engine, the device including, but not limited to: a PM emission amount estimation base-map 3 with which the base PM emission amount is computed in response to the operation condition of the engine; a PM emission amount estimation correction-map 5 that determines a correction factor for correcting the base PM emission amount computed by the PM emission amount estimation base-map 3, the correction factor being determined in response to the transient engine operation condition; a transient state judgment device 7 that judges that the engine is operated in a transient operation condition based on the change of the air excess ratio regarding the engine; a PM emission amount computation device 9 that corrects the computed base PM emission amount by multiplying the computed base PM emission amount by the correction factor computed with the PM emission amount estimation correction-map 5 only in a case where it is judged, by the transient state judgment device 7, that the engine is in a transient operation condition whereas the base PM emission amount is directly outputted in a case where it is judged that the engine is in a steady operation condition.