Fuel Tank Isolation Valve Bypass for Canister Purge Pressure Balance
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Solution Overview
Problem
Conventional evaporative emissions control systems face inefficiencies during purging operations, where vacuum draws fuel vapors back into the fuel tank isolation valve, reducing purge effectiveness and increasing the risk of leaks and unintended tailpipe emissions, and are complicated by additional hoses and mounting structures.
Innovation Solution
A fuel tank isolation valve with a main valve body and airflow bypass orifice that equalizes pressure between the fuel tank and canister during purging, and a direct mounting system to the canister without intermediate hoses, using a push-to-connect fitting and vent solenoid to control vapor flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional fuel tank isolation valve is used during purging operations, then the vacuum can draw stored vapors from the canister into the engine, but new fuel vapors from the fuel tank are also drawn into the canister and adsorb to the media, reducing purge effectiveness
Solution Approach 1:
The patent divides the vapor flow path into two separate pathways: a first pathway through the isolation valve for controlled vapor transfer, and a second pathway through the bypass orifice for pressure equalization. This segmentation allows the system to simultaneously achieve vapor storage isolation during purging while maintaining pressure balance, preventing new vapors from contaminating the canister media during purge operations.
2Reliability
If the fuel tank isolation valve is fixedly mounted to a vehicle component distal from the fuel tank and canister, then the system requires special brackets and fasteners that penetrate vehicle components, and separate hoses are routed from the fuel tank to the valve and from the valve to the canister
Solution Approach 1:
The patent merges the isolation valve directly with the canister assembly, eliminating the need for separate mounting brackets, fasteners, and intermediate hoses. The valve is positioned to receive the fuel tank vapor line directly, creating an integrated assembly that reduces the number of connection points and potential leak sources while simplifying the overall system architecture.
Solution Approach 2:
The patent extracts the isolation valve from its conventional remote mounting position and relocates it directly to the canister, removing the need for separate mounting hardware and intermediate routing components. This extraction of the valve from its traditional location and direct integration with the canister eliminates multiple potential failure points.
3Productivity
If the actuator closes the first path during purging to prevent vapor draw, then purge effectiveness improves, but pressure differential between fuel tank and canister increases
Solution Approach 1:
The patent introduces a bypass orifice as an intermediary pathway that allows controlled pressure equalization between the fuel tank and canister during purging operations. This intermediary channel maintains pressure balance while the main isolation valve remains closed to prevent vapor contamination, enabling both purge effectiveness and pressure stability to be achieved simultaneously.
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 configuration enhances the efficiency of the evaporative emissions control system by preventing excessive fuel vapor draw during purging, maintaining canister effectiveness, and reducing system complexity and leakage risks.
Implementation Method 1
This flow through the orifice can equalize pressure in a fuel tank and a canister during a purging operation to regenerate the canister.
Implementation Method 2
an actuator selectively operable to allow or inhibit vented fuel vapors to move from the first port to the second port along a first path
Implementation Method 3
The carbon or other media in the canister adsorbs the vented fuel vapors and effectively stores them to prevent them from being released to the environment.
Data Source
AI summary
A fuel tank isolation valve is provided having a main valve body including a fuel tank port and a canister port, a main bore, and an actuator selectively operable to allow or inhibit vented fuel vapors to move from the first port to the second port along a first path. The body can define an airflow bypass orifice that allows vapors to move from the first port, through the main bore, to the second port along a second path, while the actuator is in the closed mode inhibiting vapors from moving along the first path. This flow through the orifice can equalize pressure in a fuel tank and the canister during a purging operation on the canister. The valve can include a fitting that directly couples the valve to the canister without any intermediate hoses, in a cantilevered manner. A related method of use is provided.