Exhaust Gas Pressure Pulsation Engine State Detection
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Solution Overview
Problem
Current emissions test systems face challenges in accurately determining whether an engine is on or off, particularly due to issues with stagnant exhaust gas, backflow, and the difficulty in measuring minimal exhaust flow rates, which affects the accuracy of emissions mass determination.
Innovation Solution
The system employs a pressure sensor to measure the frequency and magnitude of pulsations in the exhaust gas supply line pressure, using these parameters to determine whether the engine is on or off, and adjusts the flow of diluted exhaust gas accordingly to improve emissions mass determination accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional emissions test systems measure exhaust gas flow rate to determine engine state, then emissions mass determination can be performed, but the system fails to accurately detect engine on/off states due to stagnant exhaust gas and backflow conditions
Solution Approach 1:
The patent replaces mechanical flow rate measurement systems with a pressure-based detection system using a pressure sensor to monitor pulsations in the exhaust gas supply line. This substitution eliminates the reliability issues associated with measuring minimal or stagnant exhaust flow rates while maintaining the ability to determine engine state through pressure pattern analysis
Solution Approach 2:
The patent changes the measurement parameter from exhaust gas flow rate to exhaust gas pressure. By monitoring pressure pulsations and their frequency/magnitude characteristics, the system achieves reliable engine state detection even when exhaust gas flow is minimal or stagnant, thereby resolving the contradiction between measurement precision and reliability
2Measurement precision
If the system uses complex instrumentation to accurately measure minimal exhaust flow rates, then emissions mass determination accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex flow rate measurement instrumentation with a simple pressure sensor and signal processing system. This substitution maintains emissions mass determination accuracy by using pressure pulsation characteristics to infer engine state and exhaust flow conditions, while significantly reducing device complexity and cost
3Quantity of substance
If the system measures exhaust gas flow rate during engine off states, then complete emissions data can be collected, but measurement accuracy deteriorates due to stagnant exhaust gas and backflow
Solution Approach 1:
The patent replaces flow rate measurement with pressure-based detection, enabling the system to accurately determine engine state during off periods by detecting the absence of pressure pulsations. This allows complete emissions data collection without the accuracy deterioration caused by stagnant exhaust gas
Solution Approach 2:
The pressure sensor continuously monitors the exhaust gas supply line, automatically detecting engine state changes without requiring active exhaust flow. This self-service approach ensures complete emissions data collection across all engine states while maintaining measurement precision
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 approach provides more accurate engine state detection and enhances the accuracy of emissions mass determination by differentiating between engine on and off states based on exhaust gas pressure patterns, reducing the need for costly and complex instrumentation.
Implementation Method 1
a pressure sensor configured to measure pressure in an exhaust gas supply line that supplies exhaust gas from an engine to an emissions measurement system
Data Source
AI summary
A system according to the present disclosure includes a pressure sensor and an engine state module. The pressure sensor is configured to measure pressure in an exhaust gas supply line that supplies exhaust gas from an engine to an emissions measurement system. The emissions measurement system includes a dilution tunnel, a sample probe, and a sample collector. The exhaust gas is diluted with a dilution gas in the dilution tunnel, and the sample probe supplies a portion of the diluted exhaust gas to the sample collector. The engine state module is configured to determine whether the engine is on or off based on at least one of (i) a frequency of pulsations in the exhaust gas supply line pressure and (ii) a magnitude of the pulsations in the exhaust gas supply line pressure.