Exhaust Pressure Estimation via AFR Sensor Waveform Analysis
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Solution Overview
Problem
Existing methods for estimating exhaust pressure in internal combustion engines without dedicated sensors are inaccurate due to failure to account for exhaust restrictions like particulate filters, leading to reduced accuracy in engine control and increased fuel consumption.
Innovation Solution
Utilizing an exhaust air/fuel ratio sensor to monitor periodic waveform outputs, estimating exhaust pressure based on standard deviation and average frequency of these waveforms, and adjusting engine parameters accordingly, thereby leveraging existing sensor data to improve accuracy and reduce system complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated exhaust pressure sensor is installed, then exhaust pressure measurement accuracy is improved, but system cost and control complexity increase
Solution Approach 1:
The patent uses an exhaust air/fuel ratio sensor as an intermediary device to indirectly measure exhaust pressure. Instead of installing a dedicated pressure sensor, the system leverages the existing AFR sensor's periodic waveform outputs and uses signal processing (standard deviation and frequency analysis) to derive exhaust pressure information, thereby avoiding additional hardware complexity while maintaining measurement capability
Solution Approach 2:
The patent replaces the mechanical/physical exhaust pressure sensor system with an electronic signal processing approach. By analyzing the temporal characteristics (frequency, standard deviation) of the AFR sensor's periodic waveform outputs, the system substitutes a complex mechanical measurement system with a software-based estimation method that uses existing sensor data
2Device complexity
If exhaust pressure is modeled based on intake mass airflow, then system cost is reduced, but measurement accuracy deteriorates due to not accounting for exhaust restrictions
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring the periodic waveform outputs from the AFR sensor and using the standard deviation and frequency information to dynamically adjust exhaust pressure estimates. This feedback loop allows the system to account for changing exhaust conditions including particulate filter restrictions, maintaining accuracy without requiring additional sensors or complex modeling
Solution Approach 2:
The patent changes the parameters used for exhaust pressure estimation from basic intake mass airflow to the temporal characteristics of AFR sensor waveforms (standard deviation, frequency). By analyzing how these waveform parameters change in response to exhaust pressure variations and filter loading, the system achieves more accurate estimates while keeping the hardware simple
3Reliability
If particulate filter regeneration is performed frequently, then exhaust pressure spikes are minimized, but fuel consumption increases
Solution Approach 1:
The patent enables preliminary detection of particulate filter loading conditions by analyzing trends in the AFR sensor waveform characteristics before exhaust pressure spikes occur. By detecting changes in standard deviation and frequency early in the filter loading process, the system can plan regeneration timing in advance, allowing optimization of fuel consumption by scheduling regeneration at the most efficient moments rather than reacting to pressure spikes
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 exhaust pressure estimates that account for flow restrictions, enhancing engine control and reducing fuel consumption by utilizing existing sensors instead of dedicated pressure sensors.
Implementation Method 1
the AFR sensor may comprise an exhaust gas oxygen sensor and may be configured to measure a partial pressure of oxygen in exhaust gas
Data Source
AI summary
Methods and systems are provided for estimating exhaust pressure based on an exhaust air/fuel ratio sensor. In one example, a method may comprise estimating an exhaust pressure based on periodic waveform outputs of an exhaust air/fuel ratio (AFR) sensor, and adjusting at least one engine operating parameter based on the estimated exhaust pressure. The exhaust pressure may be estimated based on one or more of the standard deviation and frequency of the periodic waveform outputs.