Ethanol Estimation Module for Virtual Flex Fuel Sensor
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Solution Overview
Problem
Closed loop fuel control systems in vehicles face challenges in maintaining accurate stoichiometric air-fuel ratios due to variations in fuel composition, particularly when ethanol is added to the fuel tank, leading to potential engine operation imbalances and diagnostic issues.
Innovation Solution
A system comprising an ethanol estimating module that adjusts baseline closed loop corrections and ethanol estimates based on fuel system errors, using a calibrated approach to prevent continuous shifting of fuel system errors and maintain accurate ethanol concentration estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous adjustment of ethanol estimate based on fuel system error is implemented, then ethanol concentration estimation accuracy is improved, but fuel system error accumulation and wander occur
Solution Approach 1:
The patent implements periodic adjustment of the ethanol estimate by enabling learn correction only after refuel events are detected. This periodic action prevents continuous adjustment that would cause error accumulation, while still updating the ethanol estimate when fuel composition actually changes. The refuel event detection mechanism ensures adjustments occur only when necessary, maintaining both accuracy and stability.
Solution Approach 2:
The system uses feedback from fuel system error to adjust the ethanol estimate, but this feedback is gated by refuel event detection. When a refuel event is detected, the system calculates the difference between current and previous fuel system errors, and adjusts the ethanol estimate accordingly. This controlled feedback mechanism prevents error accumulation while maintaining estimation accuracy when fuel composition changes.
2Measurement precision
If refuel event detection is implemented to enable learn correction, then ethanol estimation accuracy is improved, but system complexity increases
Solution Approach 1:
The control module performs multiple functions: it detects refuel events by monitoring fuel level changes, calculates fuel system errors, adjusts ethanol estimates, and manages closed-loop fuel control. By making the control module multi-functional, the patent avoids adding separate dedicated hardware for refuel detection, thereby improving ethanol estimation accuracy without proportionally increasing system complexity.
Solution Approach 2:
The system uses existing sensor data (fuel level from level sensor, fuel trim from oxygen sensors) to detect refuel events and adjust ethanol estimates. The control module leverages data already being collected for other purposes, allowing it to perform ethanol composition estimation without requiring additional sensors or complex external systems.
3Measurement precision
If baseline closed loop corrections are adjusted based on fuel system error, then ethanol estimate accuracy is improved, but diagnostic capability may be compromised
Solution Approach 1:
The system takes preliminary action to preserve diagnostic capability by storing baseline fuel system error values before adjusting the ethanol estimate. By calculating the difference between current and baseline errors, and using this difference to adjust the ethanol estimate rather than directly modifying the baseline, the system prevents actual fuel trim faults from being masked while still improving ethanol estimation accuracy.
Solution Approach 2:
The patent segments the fuel system error into two components: the baseline component (stored for diagnostic purposes) and the adjustment component (used to improve ethanol estimation). This segmentation allows the system to adjust ethanol estimates based on fuel system errors while preserving the ability to detect actual fuel trim faults by comparing current errors against the stored baseline.
Data Source
AI summary
A system for estimating fuel concentration comprises an ethanol estimating module that generates an ethanol estimate based on baseline closed loop corrections (CLC). A fuel system module controls fuel to an engine and generates a fuel system error. The ethanol estimating module selectively adjusts the baseline CLC and the ethanol estimate based on the fuel system error. A method for estimating fuel concentration comprises generating an ethanol estimate based on baseline closed loop corrections (CLC); controlling fuel to an engine and generating a fuel system error; and selectively adjusting said baseline CLC and said ethanol estimate based on said fuel system error.