Fuel Vapor Canister Loading Rate Inference via Recovery Line Monitoring
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Solution Overview
Problem
Vehicle emission control systems face challenges in accurately determining fuel vapor canister loading rates due to undiagnosed blockages in the vapor recovery line, which can lead to underestimated canister loads and increased bleed emissions, as blockages do not necessarily result in premature fuel dispenser shutoff and may not be reflected by fuel tank pressure changes.
Innovation Solution
A method is developed to infer fuel vapor canister loading based on the steady-state fuel vapor circulation rate in the vapor recovery line during refueling, using pressure and hydrocarbon sensors to monitor and adjust canister purging operations, thereby accounting for restrictions in the vapor recovery line and ensuring accurate canister load determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the vapor recovery line is blocked, then the canister loading rate increases, but the blockage goes undiagnosed leading to underestimated canister load
Solution Approach 1:
The system uses feedback from multiple sensors (pressure sensor in the vapor recovery line, hydrocarbon sensor, and fuel tank pressure sensor) to continuously monitor vapor circulation and canister loading conditions. The controller compares expected versus actual sensor readings to detect blockages and adjust canister load estimation accordingly, ensuring accurate measurement even when loading rate changes due to blockages.
Solution Approach 2:
The vapor recovery line pressure sensor acts as an intermediary indicator to detect blockages. Instead of directly measuring canister load, the system uses the pressure sensor to detect circulation rate changes caused by blockages, which then triggers adjustments to the canister load estimation through the controller.
2Object-generated harmful factors
If the vapor recovery line is blocked, then less fuel vapor is recirculated, but fuel tank pressure does not increase to indicate the blockage
Solution Approach 1:
The system implements feedback monitoring using the vapor recovery line pressure sensor to detect blockages. By continuously comparing the pressure readings against expected values during refueling operations, the controller can identify when a blockage occurs, even though fuel tank pressure does not change as it would in other blockage scenarios.
Solution Approach 2:
The system replaces reliance on fuel tank pressure changes (mechanical indicator) with electronic sensor monitoring of vapor recovery line pressure and hydrocarbon levels. This substitution allows detection of blockages through electrical/electronic measurements rather than mechanical pressure changes in the fuel tank.
3Quantity of substance
If canister load is underestimated due to undiagnosed blockage, then canister purging operations are not updated, but this leads to increased bleed emissions
Solution Approach 1:
The controller uses feedback from the vapor recovery line pressure sensor and hydrocarbon sensor to continuously update canister load estimation. When blockages are detected, the system adjusts the estimated canister load accordingly and updates purging operations to match the actual load, preventing both underestimation and associated bleed emissions.
Solution Approach 2:
The system performs self-diagnosis and self-adjustment by monitoring its own operational parameters (vapor circulation rate, pressure readings) and automatically updating canister load estimation and purging operations without external intervention, thereby preventing bleed emissions from inaccurate load assessment.
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 approach allows for accurate determination of canister loads following refueling events, enabling adjustments to canister purging operations and reducing bleed emissions by diagnosing vapor recovery line restrictions and updating loading rates accordingly.
Implementation Method 1
monitor a fuel vapor circulation rate in the vapor recovery line during a refueling event
Implementation Method 2
using pressure and hydrocarbon sensors to monitor and adjust canister purging operations
Implementation Method 3
The fuel vapors may be stored in a fuel vapor canister coupled to the fuel tank which contains adsorbent material, such as activated carbon, capable of adsorbing hydrocarbon fuel vapor
Data Source
AI summary
A method is provided, comprising indicating a fuel vapor canister load based on a steady-state fuel vapor circulation rate in a vapor recovery line during a refueling event; and adjusting a canister purging operation in response to the indicated fuel vapor canister load. Restrictions in the vapor recovery line may increase the rate of fuel vapor canister loading during a refueling event. In this way, an accurate canister load may be determined following a refueling event, and canister purging operations adjusted accordingly.