Evaporative Leak Control Module Orifice Cleaning
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Solution Overview
Problem
Existing fuel vapor recovery systems face issues with false leak diagnostics due to clogging of the reference orifice, leading to reduced customer satisfaction and increased warranty costs, as the vacuum pump is unable to reach the threshold reference vacuum when the orifice is clogged with contaminants.
Innovation Solution
A method is introduced to adjust the position of a valve in the canister bypass line to clean the reference orifice of the evaporative leak control module (ELCM), ensuring accurate leak detection by drawing contaminants to the intake manifold and maintaining the pressure at a threshold reference level during leak tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reference orifice is used for leak detection, then the leak diagnostic can be performed, but the orifice becomes clogged with contaminants leading to false failed diagnostics
Solution Approach 1:
The system performs a cleaning operation before the leak diagnostic by opening the bypass valve to allow engine vacuum to draw contaminants away from the orifice. This preliminary cleaning action prevents the orifice from being clogged during the subsequent leak test, ensuring accurate diagnostics.
Solution Approach 2:
The bypass valve acts as an intermediary component that provides an alternative flow path. By opening the bypass valve, engine vacuum is redirected through the bypass line instead of through the reference orifice, preventing contaminants from clogging the orifice while still allowing the diagnostic to proceed.
2Reliability
If the vacuum pump is used to evacuate the reference orifice, then leak detection can be performed, but the vacuum pump becomes fouled by contaminants
Solution Approach 1:
The bypass valve serves as an intermediary that redirects the vacuum flow. When opened, it provides a separate pathway for engine vacuum to act on the canister without requiring the vacuum pump to process contaminants, thereby preventing pump fouling while maintaining leak detection functionality.
Solution Approach 2:
The system extracts the vacuum source from the pump-dependent path and replaces it with engine vacuum through the bypass line. This removes the vacuum pump from direct exposure to contaminants, eliminating the fouling problem while preserving the evaporative leak check function.
3Measurement precision
If the reference orifice is cleaned periodically, then the accuracy of leak tests is enhanced, but additional valve control and timing complexity is introduced
Solution Approach 1:
The bypass valve is designed to serve multiple functions: it enables the cleaning operation, provides an alternative vacuum path, and can be integrated with existing engine management systems. This multi-functionality reduces the need for additional dedicated components, mitigating the complexity increase.
Solution Approach 2:
The system uses feedback from the engine management system to control the bypass valve timing. The valve is opened at appropriate moments based on engine operating conditions and diagnostic requirements, allowing automated cleaning without requiring complex manual intervention or additional sensing infrastructure.
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 enhances the accuracy of leak tests, reduces vehicle downtime and maintenance costs, and increases customer satisfaction by periodically cleaning the orifice to prevent fouling and ensure reliable diagnostics.
Implementation Method 1
the vaporized hydrocarbons (HCs) are stored in a fuel vapor canister packed with an adsorbent which adsorbs and stores the vapors
Implementation Method 2
The vacuum pump may be activated, which in turn may evacuate a small volume comprising a reference orifice
Implementation Method 3
The contaminants may clog the reference orifice... By cleaning the reference orifice periodically or in response to a leak test not being passed, an accuracy of the leak test may be enhanced
Data Source
AI summary
Methods and systems are provided for a fuel system. In one example, a method may include cleaning an orifice of an ELCM. The cleaning includes adjusting a position of a valve in a passage to fluidly couple a reference orifice of the ELCM to an intake manifold.