Variable Orifice Valve Diagnostics via Pressure Manipulation
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Solution Overview
Problem
Variable orifice valves in fuel vapor recirculation lines can become stuck in either the open or closed configuration, leading to undesired evaporative emissions and inefficient canister loading, making it challenging to diagnose and address these issues effectively.
Innovation Solution
Active manipulation of pressure in the fuel system during refueling events to bias the variable orifice valve into high-flow or low-flow positions, allowing for the monitoring of canister loading rates to determine if the valve is stuck, using a combination of mechanical and electromechanical actuation based on pressure thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable orifice valve is used to dynamically regulate fuel vapor flow rate through the recirculation line, then the system can adapt to variability in fuel flow rates from different dispensers and prevent both canister overload and atmospheric release of hydrocarbons, but the valve may become stuck in one of the open or closed configurations due to aging, leading to undesired evaporative emissions or inefficient canister loading
Solution Approach 1:
The diagnostic system performs preliminary actions by actively manipulating pressure during refueling events to bias the variable orifice valve into extreme positions (fully open or fully closed) and monitoring canister loading rates to detect valve degradation before it causes emissions problems or canister overload
Solution Approach 2:
The system implements feedback by monitoring canister loading rates and comparing them against expected ranges to detect when the variable orifice valve is stuck, then providing feedback to the controller to adjust valve operation or alert the operator to the degradation condition
2Quantity of substance
If the variable orifice valve is stuck closed, then canister loading increases beyond desired levels, but if the variable orifice valve is stuck open, then evaporative emissions are released to atmosphere via the fuel filler neck inlet
Solution Approach 1:
The system replaces mechanical valve positioning with active pressure manipulation during refueling events to bias the valve into extreme positions for diagnostic purposes, allowing detection of stuck conditions through electronic monitoring rather than purely mechanical operation
Solution Approach 2:
The system changes operational parameters by actively manipulating pressure during refueling to force the variable orifice valve into extreme open or closed positions, enabling diagnostic detection of valve degradation through monitoring canister loading rates under these biased conditions
3Measurement precision
If active pressure manipulation is performed during refueling events to bias the variable orifice valve into extreme positions for diagnosis, then accurate detection of valve degradation is enabled, but additional control complexity is introduced to the refueling process
Solution Approach 1:
The pressure manipulation system serves multiple functions: it enables diagnostic detection of valve degradation, maintains normal refueling operation, and provides adaptive control based on detected valve conditions, making the added complexity worthwhile through multi-functionality
Data Source
AI summary
Methods and system are provided for indicating whether a variable orifice valve positioned in a fuel vapor recovery line of a vehicle fuel system is degraded. In one example, a method may include actively manipulating a pressure in the fuel system during a refueling event, and indicating whether the variable orifice valve is degraded based on a loading rage of a fuel vapor storage canister with fuel vapors while the pressure is actively manipulated. In this way, it may be determined as to whether the variable orifice valve is stuck in a high-flow or a low-flow position such that mitigating action may be taken to reduce or avoid release of undesired evaporative emissions to atmosphere.