Exhaust Gas Analysis System Acceleration Error Cancellation
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Solution Overview
Problem
Conventional exhaust gas analysis systems on vehicles experience measurement errors due to the influence of acceleration, which affects differential pressure sensors used for flow rate measurements, leading to control errors in the sample flow rate.
Innovation Solution
The exhaust gas analysis system aligns the pressure sensitive elements of the diluent gas and diluted exhaust gas flow rate measurement mechanisms in the same direction to cancel out acceleration-induced measurement errors, ensuring that the sample flow rate is accurately controlled by making measurement errors equal or approximately equal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If differential pressure flowmeters are used for flow rate measurement in mobile exhaust gas analysis, then flow rate measurement capability is provided, but measurement precision deteriorates due to acceleration influence
Solution Approach 1:
The patent converts the harmful acceleration influence into a beneficial effect by intentionally introducing acceleration into the reference pressure measurement in the same direction and magnitude as the measurement pressure. This causes the acceleration errors to cancel out when calculating the differential pressure, transforming the harmful acceleration effect into a benefit that eliminates measurement errors during vehicle movement.
Solution Approach 2:
The patent introduces asymmetry in the sensor arrangement by positioning the reference pressure sensor and measurement pressure sensor such that both experience acceleration in the same direction. This asymmetric configuration relative to the vehicle's motion direction ensures that acceleration affects both sensors equally, enabling error cancellation while maintaining different functional roles for each sensor.
2Measurement precision
If the sample flow rate is controlled as a difference between diluted exhaust gas flow rate and diluent gas flow rate, then flow rate control capability is provided, but control precision deteriorates due to cumulative measurement errors
Solution Approach 1:
The patent applies the same acceleration compensation principle to both the diluted exhaust gas flow rate measurement and the diluent gas flow rate measurement. By introducing acceleration in the same direction for both measurements, the cumulative errors in calculating the sample flow rate difference are reduced, improving control precision and reliability.
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 configuration significantly reduces the influence of acceleration on the sample flow rate, enhancing the accuracy of flow rate measurements and control in exhaust gas analysis systems, particularly during vehicle operations.
Implementation Method 1
a differential pressure flowmeter, such as a Venturi flowmeter, is used for the diluent gas flow rate measurement mechanism and the diluted exhaust gas flow rate measurement mechanism
Implementation Method 2
a differential pressure flowmeter, such as a Venturi flowmeter
Data Source
AI summary
The present invention includes an exhaust gas flow channel that permits passage of an exhaust gas, a diluent gas flow channel that permits passage of a diluent gas, a main flow channel that permits passage of a diluted exhaust gas, a diluted exhaust gas flow rate measurement mechanism disposed on the main flow channel, and a diluent gas flow rate measurement mechanism disposed on the diluent gas flow channel. The diluted exhaust gas flow rate measurement mechanism and the diluent gas flow rate measurement mechanism each have a pressure sensor section. Furthermore, a pressure sensitive element of the pressure sensor section in the diluted exhaust gas flow rate measurement mechanism, and a pressure sensitive element of the pressure sensor section in the diluent gas flow rate measurement mechanism, are oriented in an identical direction in order to reduce an influence of acceleration in association with movement of a mobile object.