SAFR Sensor System Using Conductivity and Permittivity
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Solution Overview
Problem
Conventional sensors are limited in measuring the Stoichiometric Air to Fuel Ratio (SAFR) of fuel mixtures containing both ethanol and methanol, as they require calibration for either ethanol or methanol, leading to inaccuracies and delays in adjusting fuel composition, which results in excess emissions and performance loss.
Innovation Solution
A sensor system comprising a measurement cell with electrodes to determine conductivity and permittivity, and a temperature sensor to calculate the SAFR, which can be fed forward to an engine control module, allowing for real-time adjustments independent of the type of alcohol present.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional flex fuel sensor is used to determine alcohol concentration, then the sensor can be calibrated for either ethanol or methanol, but it cannot measure both types of alcohol accurately
Solution Approach 1:
The sensor system measures multiple properties (permittivity, conductivity, temperature) simultaneously to determine SAFR for any alcohol type without requiring separate calibration for each fuel type. The processor uses these combined measurements to universally identify both ethanol and methanol concentrations.
Solution Approach 2:
The invention transitions from measuring a single parameter (concentration for specific fuel types) to measuring multiple parameters (permittivity, conductivity, temperature) to determine SAFR. This multi-parameter approach enables accurate measurement across different alcohol types without recalibration.
2Measurement precision
If a wide range oxygen sensor (Lambda sensor) is used to measure oxygen in exhaust, then the fuel to air ratio can be adjusted, but the adjustment occurs only after combustion and there is a several-minute delay
Solution Approach 1:
The sensor measures alcohol concentration and determines SAFR before combustion occurs, allowing the engine control system to pre-adjust the fuel to air ratio. This eliminates the delay inherent in post-combustion feedback methods.
Solution Approach 2:
The system implements a feedback mechanism where the measured SAFR is used to adjust fuel injection in real-time, creating a closed-loop control system that continuously optimizes the fuel to air ratio based on actual fuel composition.
3Measurement precision
If a near infrared sensor is used to eliminate concentration measurement of gasoline and alcohol blends, then good accuracy is achieved, but the cost is high and environmental durability is limited
Solution Approach 1:
The invention replaces the optical near-infrared sensor system with an electrical measurement system using electrodes to measure permittivity and conductivity. This substitution maintains measurement accuracy while reducing cost and improving durability.
Solution Approach 2:
The system transitions from optical parameter measurement (near-infrared absorption) to electrical parameter measurement (permittivity and conductivity). This change in measurement domain achieves the same analytical goal with more robust and cost-effective sensors.
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
The system accurately determines the SAFR of fuel mixtures, enabling real-time adjustments to minimize emissions and improve engine performance by correlating dielectric properties with the air-to-fuel ratio, reducing the need for post-combustion feedback and addressing the limitations of existing sensors.
Implementation Method 1
The electrodes are constructed and arranged to provide data for determining a conductivity and permittivity of the fuel mixture
Implementation Method 2
The electrodes are constructed and arranged to provide data for determining a conductivity and permittivity of the fuel mixture
Implementation Method 3
A temperature sensor is constructed and arranged to measure a temperature of the fuel mixture
Data Source
AI summary
A sensor system (36) determines the Stoichiometric Air to Fuel Ratio (SAFR) of fuel mixtures. The system includes a first electrode (12) and a second electrode (14), with the first electrode surrounding the second electrode so that a fuel mixture can flow between the first electrode and the second electrode. The electrodes are constructed and arranged to provide data for determining a conductivity and permittivity of the fuel mixture. A temperature sensor (18) is constructed and arranged to measure a temperature of the fuel mixture. A processor (19) is constructed and arranged to determine the SAFR of the fuel mixture based on the measured temperature and permittivity of the fuel mixture.