Fuel Level Indicator Diagnosis in Saddle Tanks via Pressure Correlation
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Solution Overview
Problem
Existing fuel level indicator systems in bifurcated fuel tanks, particularly in saddle tanks, face inaccuracies due to issues like bent float arms, leaks, and fuel sloshing, leading to incorrect fuel level readings and prolonged diagnostic times, especially in hybrid-electric vehicles.
Innovation Solution
Diagnosing fuel level indicators during refueling events by correlating the timing of fuel level indicator outputs with deviations in fuel tank pressure spikes, which provides a faster and more accurate assessment of indicator degradation and fuel levels, robust to leaks and fuel system deficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fuel level indicators are monitored over an extended duration (e.g., 100 miles) to obtain diagnosis of the entire range of fuel level indicator output, then the completeness of diagnosis is improved, but the diagnostic time is excessively prolonged
Solution Approach 1:
The patent applies preliminary action by performing fuel level indicator diagnosis during refueling events, which occur periodically during normal vehicle operation. Instead of waiting to accumulate extensive operational data over 100 miles, the system utilizes the refueling moment to immediately assess fuel level indicator accuracy by comparing indicator readings with actual fuel tank pressure measurements. This preliminary diagnosis during refueling provides timely detection of indicator degradation without requiring extended monitoring periods.
2Measurement precision
If engine vacuum or vacuum pump is utilized to reduce fuel tank pressure to reference pressure and infer fuel level based on rate of pressure change, then fuel level can be determined, but the diagnosis is inaccurate due to fuel system leaks altering the rate of pressure change
Solution Approach 1:
The patent introduces fuel tank pressure as an intermediary measurement to diagnose fuel level indicator accuracy. Instead of directly inferring fuel level from pressure change rate during vacuum application (which is affected by leaks), the system uses fuel tank pressure readings taken during refueling events as a reference point. The fuel level indicator diagnosis is performed by comparing indicator output with the actual fuel level inferred from pressure measurements during refueling, when the system is open to atmospheric pressure and leak effects are minimized.
3Measurement precision
If floating sensor arm bends due to excessive vacuum levels from leaking purge valves, then the sensor over-estimates fuel amount, but the vehicle may run out of fuel during a trip
Solution Approach 1:
The patent implements feedback by continuously monitoring fuel level indicator output during refueling events and comparing it with actual fuel level measurements derived from fuel tank pressure. When the fuel level indicator shows degradation (such as over-estimation due to bent float arm), the system generates a diagnostic indication to alert the operator. This feedback mechanism enables early detection of sensor malfunction, allowing timely intervention before the vehicle runs out of fuel during operation.
4Reliability
If evaporative emissions leak test is performed, then emissions compliance can be verified, but fuel sloshing during sharp vehicle maneuvers generates fuel vapor pressure spike resulting in incorrect diagnosis
Solution Approach 1:
The patent applies preliminary action by diagnosing fuel level indicators during refueling events before performing evaporative emissions leak tests. By ensuring fuel level indicators are functioning accurately through preliminary diagnosis, the system prevents incorrect emissions leak test results that would occur due to fuel sloshing. The refueling event serves as a preparatory step to verify sensor accuracy, eliminating the harmful effect of fuel vapor pressure spikes during subsequent emissions testing.
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 method enables faster, more complete, and accurate diagnosis of fuel level indicators, reducing false positives and negatives, and ensuring the reliability of evaporative emissions leak tests.
Implementation Method 1
Diagnosing fuel level indicators during refueling events by correlating the timing of fuel level indicator outputs with deviations in fuel tank pressure spikes
Data Source
AI summary
Methods and systems are provided for diagnosing fuel level indicators in a saddle fuel tank. In one example, a method may include determining degradation of each of the first and the second fuel level indicators included in a first compartment and a second compartment of a saddle tank based on a correlation between changes in fuel tank pressure during the refueling event and an indication by the fuel level indicators of the first and the second compartment reaching full capacity.