Fuel Trap Baffle and Venturi for EVAP Canister Noise
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Solution Overview
Problem
Existing evaporative emission control systems face issues with contamination of activated carbon due to liquid fuel traces and generate noise during purge valve operation, which affect the performance and vibration levels in vehicles.
Innovation Solution
A fuel vapor storage canister with an integral fuel trap featuring bifurcated chambers and a venturi design that traps liquid fuel traces and attenuates noise by using a baffle and venturi to collect and convert liquid fuel into vapor, reducing vibrations and acoustic rattle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuel trap is exposed to the purge line to extract liquid fuel trace, then liquid fuel trace can be effectively removed, but noise is generated due to wave disturbances in the purge line during purge valve operation
Solution Approach 1:
The patent introduces a decoupling mechanism where the fuel trap is connected to the purge line through a flexible hose rather than direct exposure. This flexible connection acts as an intermediary that isolates the fuel trap from the high-frequency pressure waves generated during purge valve operation, thereby reducing noise and vibration transmission while maintaining the fuel trap's effectiveness in removing liquid fuel traces
Solution Approach 2:
The patent extracts the fuel trap from direct connection to the rigid purge line and relocates it to a position connected via flexible hose. This separation removes the fuel trap from the harmful acoustic environment of the purge line while preserving its functional connection to the EVAP system, allowing it to continue extracting liquid fuel traces without being subjected to purge-induced noise and vibration
2Object-affected harmful factors
If existing systems use coaxial expansion joint or resonator along the purge line, then some noise attenuation is achieved, but the design is non-optimal and does not sufficiently suppress purge noise
Solution Approach 1:
The patent replaces complex, expensive noise attenuation devices (coaxial expansion joints, resonators) with a simple flexible hose connection. The flexible hose is a straightforward, easily replaceable component that provides sufficient noise isolation without the complexity and cost of engineered acoustic devices, achieving practical noise reduction with minimal design overhead
3Reliability
If liquid fuel trace accumulates in activated carbon, then the activated carbon becomes choked, but existing fuel traps do not effectively prevent this accumulation
Solution Approach 1:
The patent positions the fuel trap upstream in the vapor flow path, before the vapor enters the activated carbon canister. This preliminary action allows the fuel trap to intercept and remove liquid fuel traces from the vapor stream in advance, preventing the liquid from reaching and choking the activated carbon, thereby preserving the carbon's adsorption/desorption productivity throughout its service life
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
The solution effectively suppresses purge noise and prevents liquid fuel from choking the activated carbon, enhancing the adsorption and desorption capacity while minimizing vibrations and sound radiation, thus improving the overall performance of the EVAP system.
Implementation Method 1
The venturi creates a region of low pressure during purging, which evacuates the cavity by suction
Implementation Method 2
the liquid trace falls through an opening in a partition
Implementation Method 3
The activated carbon adsorbs fuel vapor from the fuel tank
Implementation Method 4
which aids in converting the liquid trace to fuel vapor
Data Source
AI summary
A fuel vapor storage canister including an integral fuel trap is provided. The fuel trap includes bifurcated chambers with the dual purpose of trapping liquid trace and attenuating noise entering the canister shell and tank line. The upper chamber includes a baffle to block and collect liquid trace, the liquid trace falling through an opening in a partition for collection in a fuel trace collector. The fuel trace collector is suitably positioned within the lower chamber, immediately beneath the opening, and includes a cavity and a venturi. The venturi creates a region of low pressure during purging, which evacuates the cavity by suction. The cavity optionally includes an activated carbon billet, which maintains the pressure level in the fuel vapor line above a predetermined minimum value and which aids in converting the liquid trace to fuel vapor as well as in further attenuating noise escaping into the tank line.