Differential Pressure Sensor Offset Correction in Air Ducts
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Solution Overview
Problem
Differential pressure sensors in air ducts of internal combustion engines face offset errors due to component drifts and interference pressures, leading to inaccurate pressure difference measurements over the sensor's service life.
Innovation Solution
A method to correct the offset by calibrating the sensor in predetermined operating situations, such as when the engine is switched off, and filtering output signal values over time to account for noise, while ignoring interference pressures that distort measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the offset is determined based on a known pressure difference during operation, then the initial measurement accuracy is improved, but the measurement precision deteriorates over service life due to component drift
Solution Approach 1:
The patent applies preliminary action by performing offset calibration during a predetermined operating situation (engine off, no mass flow) before normal operation begins. This preliminary calibration establishes an accurate baseline offset value that accounts for component characteristics at that moment, which is then used to correct measurements during subsequent operation, thereby maintaining measurement consistency over service life.
Solution Approach 2:
The patent implements feedback by continuously monitoring the differential pressure sensor output and comparing it against expected values during the predetermined operating situation. The measured offset is fed back to the control device, which automatically applies the correction to ongoing measurements, ensuring long-term measurement reliability without manual intervention.
2Measurement precision
If the output signal is filtered over a predetermined time period, then the measurement precision is improved by reducing noise effects, but the response time increases
Solution Approach 1:
The patent applies periodic action by filtering the output signal over a predetermined time period during the calibration phase. This time-period filtering reduces the influence of random noise and outliers on the offset determination while the system is in the predetermined operating situation, thereby improving measurement precision without affecting normal operational response time.
3Adaptability or versatility
If calibration is performed during operation, then the adaptability is improved, but the measurement precision deteriorates due to interference pressure
Solution Approach 1:
The patent applies preliminary anti-action by deliberately selecting a predetermined operating situation (engine off, no mass flow) where interference pressure is eliminated or minimized before performing offset calibration. This preliminary condition preparation prevents interference pressure from affecting the calibration measurement, ensuring high precision offset determination that can then be adaptively applied during normal operation despite varying interference conditions.
Data Source
AI summary
A method for correcting an offset for a pressure difference measured using a differential pressure sensor situated in an air duct. The offset is computed using an output signal of a pressure sensor, including: transferring the air duct into a predetermined operating situation in which a predetermined pressure difference is considered to be applied to the differential pressure sensor, measuring a level of the output signal in the predetermined operating situation, and computing the offset based on the measured level of the output signal.