Fuel Level Estimation Using Pressure Changes in Closed Vapor Systems
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Solution Overview
Problem
Existing fuel level estimation devices require refueling timing and fuel injection amount resetting for accurate malfunction diagnosis of fuel level gauges, making them impractical for precise fuel level estimation and sensor abnormality detection.
Innovation Solution
A fuel level estimation device comprising an information acquiring unit, a flow rate controlling unit, and a fuel level estimating unit that estimates fuel levels based on the total volume of a closed fuel vapor system and the occupied volume of gas, using changes in internal pressure before and after pressure-reducing treatment, and a reference discharging rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fuel consumption is calculated by integrating fuel injection amounts, then fuel level can be estimated, but refueling timing must be tracked and fuel injection amount integrated value must be reset for accurate malfunction diagnosis
Solution Approach 1:
The invention extracts the fuel vapor from the fuel tank and measures its volume directly using a pressure sensor in the evaporative emission control system. This separates the fuel level measurement function from the fuel injection integration process, eliminating the need to track refueling timing and reset integrated values.
Solution Approach 2:
The invention replaces the mechanical/integration-based fuel consumption tracking system with a pressure-based gas volume measurement system. By using the pressure sensor to detect fuel vapor volume changes in the canister, the system substitutes complex integration calculations with direct physical measurement.
2Reliability
If fuel level is detected using a fuel level sensor, then fuel level information is available, but the system cannot diagnose sensor malfunctions without refueling tracking
Solution Approach 1:
The invention creates a feedback mechanism where the pressure sensor continuously monitors fuel vapor volume, providing real-time fuel level information that can be compared against expected values. This enables continuous validation of fuel level data without requiring periodic manual intervention for refueling tracking.
Solution Approach 2:
The evaporative emission control system performs self-diagnosis by monitoring its own pressure changes. The system can detect anomalies in fuel vapor volume that indicate either actual fuel level changes or potential sensor malfunctions, enabling autonomous malfunction detection without external refueling tracking.
3Measurement precision
If pressure-reducing treatment is applied to measure gas volume, then occupied volume can be calculated from pressure change, but flow rate must be controlled for accurate measurement
Solution Approach 1:
The invention introduces a flow rate controlling valve as an intermediary between the pressure-reducing treatment and the measurement process. This valve mediates the pressure change by controlling gas flow, ensuring that pressure changes are due to volume measurement rather than uncontrolled flow, thereby enabling accurate measurement while maintaining operational simplicity.
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
Enables precise fuel level estimation and abnormality diagnosis of fuel level sensors regardless of refueling, improving accuracy and reliability by calculating occupied gas volume using pressure changes and reference discharging rates.
Implementation Method 1
a flow rate controlling unit configured to control, by actuating a negative pressure source, a flow rate of fuel vapor-containing gas present in the closed fuel vapor system
Implementation Method 2
a fuel level estimating unit configured to estimate a fuel level based on a total volume of the closed fuel vapor system and an occupied volume of the gas, wherein the fuel level estimating unit estimates the occupied volume of the gas on the basis of a change in the closed system internal pressure before and after the closed fuel vapor system is subjected to pressure-reducing treatment
Implementation Method 3
a canister used to adsorb fuel vapor generated in the fuel tank
Data Source
AI summary
Disclosed is a fuel level estimation device including: an information acquiring unit acquiring information about a closed system internal pressure of a closed fuel vapor system including the fuel tank, a vent passage, and a canister; a flow rate controlling unit controlling, by actuating a negative pressure pump, a flow rate of fuel vapor-containing gas in the closed fuel vapor system; a fuel level estimating unit estimating a fuel level based on a total volume of the closed fuel vapor system and an occupied volume of the gas. The fuel level estimating unit estimates the occupied volume of the gas by using a change in a closed system internal pressure before and after the closed fuel vapor system is subjected to pressure-reducing treatment for a predetermined interval and a reference discharging rate when the gas is subject to the pressure-reducing treatment. An abnormality diagnostic apparatus is also disclosed.