EVAP Canister Testing via Fuel Vapor Density Control
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Solution Overview
Problem
Current systems for evaluating the performance of evaporative emissions (EVAP) canisters in vehicles do not accurately test their capacity and fuel vapor concentration, leading to potential breakthroughs where fuel vapor is vented to the atmosphere.
Innovation Solution
A system comprising an evaporator, fuel vapor supply line, gas density meter, and valve control module to measure and adjust fuel vapor concentration, ensuring consistent test conditions by accounting for fuel weathering and reducing the need for frequent gas density meter calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fuel vapor concentration is not accurately measured and adjusted, then test accuracy deteriorates leading to potential breakthroughs, but implementing measurement and adjustment systems increases device complexity
Solution Approach 1:
The patent replaces complex mechanical measurement systems with a gas density meter that uses optical or electrical principles to measure fuel vapor concentration. The valve control module then automatically adjusts the fuel vapor supply based on density measurements, substituting manual mechanical adjustment with automated control based on physical property measurements.
Solution Approach 2:
The gas density meter acts as an intermediary device that indirectly measures fuel vapor concentration by measuring gas density, which correlates to concentration. This intermediary measurement approach simplifies the direct measurement of concentration while maintaining accuracy.
2Reliability
If fuel vapor supply is not precisely controlled, then test reliability deteriorates due to variable test conditions, but implementing precise control increases device complexity
Solution Approach 1:
The valve control module continuously monitors fuel vapor concentration (via gas density measurements) and automatically adjusts the fuel vapor supply valve position based on the measured values. This closed-loop feedback control ensures consistent test conditions while using a relatively simple control algorithm.
Solution Approach 2:
The system automatically self-regulates the fuel vapor supply based on real-time density measurements without requiring manual intervention. The valve control module autonomously maintains target concentration levels, making the system self-correcting and reliable.
3Measurement precision
If frequent calibration of gas density meter is required, then measurement accuracy is maintained, but loss of time and productivity increase
Solution Approach 1:
The system performs preliminary calibration of the gas density meter before actual testing begins, establishing baseline accuracy. During subsequent tests, the pre-calibrated system maintains accuracy without requiring frequent re-calibration, allowing continuous testing operations.
Solution Approach 2:
Instead of continuous or frequent calibration, the system implements periodic calibration at predetermined intervals or before specific test sequences. This periodic maintenance approach balances measurement accuracy with productivity by minimizing calibration frequency while maintaining reliability.
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 system accurately determines fuel vapor concentration, reduces fuel usage, and extends the number of test cycles, enhancing the evaluation of EVAP canister performance while minimizing costs.
Implementation Method 1
a gas density meter configured to measure a density of the fuel vapor mixture flowing through the fuel vapor supply line
Implementation Method 2
an evaporator configured to contain liquid fuel
Implementation Method 3
The canister typically contains activated carbon that adsorb fuel vapor within the canister
Data Source
AI summary
A system for testing an evaporative emissions (EVAP) canister of a vehicle according to the present disclosure includes an evaporator configured to contain liquid fuel, a fuel vapor supply line configured to deliver a mixture of fuel vapor and carrier gas from the evaporator to the EVAP canister, and a fuel vapor supply valve disposed in the fuel vapor supply line. The test system further includes a gas density meter configured to measure a density of the fuel vapor mixture flowing through the fuel vapor supply line, and a valve control module configured to control a position of the fuel vapor supply valve to adjust a flow of fuel vapor from the evaporator to the EVAP canister based on the fuel vapor mixture density.