Estimating Intake Air Humidity via Exhaust Emissions
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Solution Overview
Problem
Existing humidity sensors in internal combustion engines are prone to inaccuracy and degradation at high temperatures, affecting the adjustment of engine operating parameters such as air-fuel ratio, spark timing, and exhaust gas recirculation, which can impact engine efficiency and emissions.
Innovation Solution
The method involves estimating intake air humidity based on engine-out emissions like NOx and particulate matter concentrations, using sensors to correlate these emissions with humidity levels and adjust engine parameters accordingly, reducing the reliance on potentially inaccurate humidity sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a humidity sensor is located in the intake manifold or charge air cooler to determine intake air humidity, then humidity measurement is achieved, but the sensor becomes inaccurate and prone to degradation under high engine operating temperatures
Solution Approach 1:
The patent uses exhaust gas emissions (NOx, particulate matter) as an intermediary indicator to indirectly determine intake air humidity. Instead of placing a humidity sensor directly in the high-temperature intake manifold, the system measures emissions downstream and correlates them with humidity levels through a model, avoiding direct sensor exposure to harsh conditions.
Solution Approach 2:
The patent replaces the physical humidity sensor with an emissions-based measurement system. By substituting the direct mechanical/chemical sensor with an optical/electronic emissions detection system, the solution avoids the degradation issues of traditional humidity sensors while maintaining measurement capability through computational correlation.
2Difficulty of detecting and measuring
If traditional humidity sensors are used in high temperature environments, then humidity detection is possible, but the sensors degrade and provide inaccurate readings affecting engine parameter adjustment
Solution Approach 1:
The system uses exhaust emissions as a mediator to infer humidity levels. The emissions measurements serve as an indirect proxy that correlates with intake air humidity, allowing the system to detect humidity without exposing sensors to high-temperature degradation zones.
Solution Approach 2:
The patent creates a computational model that copies or replicates the humidity detection function through emissions data. Instead of relying on a physical sensor in the harsh environment, the system uses a mathematical model that maps emissions characteristics to humidity levels, effectively copying the detection capability without the physical vulnerability.
Data Source
AI summary
Embodiments for estimating intake air humidity in an engine are provided. In one example, an engine method comprises adjusting an engine parameter in response to intake air humidity estimated based on a concentration of one or more engine-out emissions. In this way, one or more exhaust emission sensors may be used to estimate intake air humidity.