Oxygen Sensor Feedback for Engine Scavenging Air Correction
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Solution Overview
Problem
Existing engine control systems face inaccuracies in adjusting engine parameters due to uncorrected cylinder trapped air and scavenging air amounts, leading to undesirable adjustments in spark timing and valve timing, which can result in increased emissions and reduced engine performance.
Innovation Solution
The method involves correcting cylinder trapped air and scavenging air amounts using an oxygen sensor, allowing for separate adjustment of spark timing and valve overlap, thereby compensating for conditions not sensed by mass air sensors or manifold absolute pressure sensors, and improving the accuracy of air flow calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If uncorrected cylinder trapped air amount or bulk air amount is used for adjusting engine control parameters, then engine control parameters can be adjusted, but the adjustments are made in an undesirable way leading to increased emissions and reduced engine performance
Solution Approach 1:
The patent applies feedback by using an oxygen sensor to measure the actual oxygen content in exhaust gases and using this information to correct the cylinder trapped air amount calculation. The corrected air amount is then fed back to the control system to adjust spark timing and valve timing, creating a closed-loop control system that continuously optimizes engine performance and reduces emissions.
Solution Approach 2:
The patent replaces the traditional mechanical sensing approach (relying solely on mass air flow sensors or MAP sensors) with an oxygen sensor-based correction system. This substitution allows for more accurate determination of actual cylinder trapped air amount by using chemical analysis of exhaust gases rather than purely mechanical pressure or flow measurements.
2Measurement precision
If uncorrected cylinder trapped air amount is used, then engine control parameters can be adjusted, but the output of modeled systems does not track actual system conditions as close as desired
Solution Approach 1:
The oxygen sensor provides continuous feedback on the actual combustion conditions, allowing the control system to correct deviations between modeled and actual system conditions. This feedback loop ensures that the cylinder trapped air amount calculation accurately reflects real-world conditions, improving the reliability of engine management decisions.
3Device complexity
If mass air sensor or MAP sensor is used to determine cylinder trapped air amount, then air flow can be sensed, but sensitivities to changes in exhaust system manifold pressure and valve timing cannot be removed
Solution Approach 1:
The oxygen sensor acts as an intermediary that indirectly measures the effectiveness of air delivery to the cylinder by analyzing exhaust gas composition. Rather than directly measuring air flow or pressure, the oxygen sensor provides a stable indicator of actual combustion conditions that is insensitive to variations in manifold pressure and valve timing, thereby stabilizing the air amount measurement.
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 reduces vehicle emissions, enhances engine performance by accurately determining exhaust gas residuals, and allows for closed-loop control of scavenging supplied to exhaust gas after-treatment devices, leading to improved engine efficiency and reduced errors in air-fuel ratio calculations.
Implementation Method 1
correcting both cylinder trapped air amount and cylinder scavenging air amount via an oxygen sensor
Data Source
AI summary
A method for correcting a total cylinder air flow during scavenging by way of an oxygen sensor is disclosed. Additionally, cylinder trapped air amount and cylinder scavenging air amount are adjusted based on the corrected total cylinder air flow. The approach may reduce sensitivity between cylinder air flow estimates and fuel supplied for combustion.