Evaporative Leak Test Threshold Adjustment for High RVP Fuel
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Solution Overview
Problem
Existing evaporative emissions leak test methods, such as EONV and ELCM tests, are prone to errors when using fuels with high Reid Vapor Pressure (RVP), leading to false pass or fail results due to the counteractive effects of highly volatile fuels on pressure thresholds.
Innovation Solution
Adjusting pressure thresholds based on fuel volatility and Reid Vapor Pressure (RVP) to compensate for the effects of high RVP fuels, ensuring accurate leak detection by determining and adjusting reference vacuum thresholds in both ELCM and EONV tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EONV test is performed with high RVP fuel, then pressure rise is observed, but false pass occurs due to counteractive pressure effect
Solution Approach 1:
The system dynamically adjusts the pressure threshold parameter based on detected fuel RVP characteristics. When high RVP fuel is detected, the threshold is modified to account for the counteractive pressure effect, preventing false pass results while maintaining accurate leak detection capability.
Solution Approach 2:
The system incorporates feedback from fuel volatility detection into the leak test threshold determination. By monitoring fuel RVP and using this information to adjust pressure thresholds, the system compensates for the counteractive pressure effects of high RVP fuels.
2Reliability
If ELCM test is performed with high RVP fuel, then vacuum is drawn, but false failure occurs due to counteractive vacuum effect
Solution Approach 1:
The system modifies the vacuum threshold parameter based on fuel RVP characteristics. When high RVP fuel is detected, the vacuum threshold is adjusted to compensate for the counteractive vacuum effect, preventing false failure results while maintaining accurate leak detection.
Solution Approach 2:
The system uses feedback from fuel volatility detection to adjust vacuum test thresholds. By incorporating RVP information into the threshold determination, the system compensates for the counteractive vacuum effects and reduces false failures.
3Ease of operation
If fixed pressure threshold is used for leak test, then test is simple, but false results occur with variable fuel volatility
Solution Approach 1:
The system transitions from a static, fixed threshold approach to a dynamic threshold adjustment mechanism. The pressure and vacuum thresholds are automatically modified based on detected fuel RVP characteristics, allowing the same test procedure to adapt to varying fuel conditions and maintain high accuracy without complicating the overall test operation.
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 reduces false failures and false passes in leak tests, providing a more robust and accurate assessment of the fuel system's integrity without adding additional components, thereby minimizing unnecessary warranty services and producer risk.
Implementation Method 1
the fuel vapor of a high RVP fuel may counteract the vacuum pull of the ELCM pump
Implementation Method 2
The pressure in such a fuel system will increase if the tank is heated further as liquid fuel vaporizes
Implementation Method 3
As a fuel tank cools down, a vacuum is generated therein as fuel vapors condense to liquid fuel
Data Source
AI summary
A method for an evaporative emissions leak test, comprising: adjusting a pressure threshold based on a fuel volatility of a fuel contained in a fuel tank; and performing the evaporative emissions leak test based on the adjusted pressure threshold. By determining fuel volatility and adjusting a pressure threshold based on the fuel volatility, a more robust and accurate evaporative emissions leak test may be employed without adding additional components to a fuel system.