Canister Grid with Variable Aperture Ratio for Uniform Air Flow
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Solution Overview
Problem
The existing canister design experiences decreased purging efficiency due to uneven air flow patterns within the chambers, with faster air flow at the center and slower air flow at the periphery, which hinders sufficient fuel desorption at the periphery.
Innovation Solution
A grid with a perforated design featuring a higher aperture ratio from the center to the periphery, comprising small holes at the center and larger holes towards the edges, or radially arranged holes that decrease in size towards the center, is used to hold adsorbents within the filling chamber, ensuring more uniform air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional grid with uniform hole distribution is used, then the grid structure is simple and easy to manufacture, but the air flow becomes uneven with faster flow at the center and slower flow at the periphery, decreasing purging efficiency
Solution Approach 1:
The grid is designed with non-uniform hole distribution where the aperture ratio increases from the center toward the periphery. Specifically, smaller holes are arranged at the center and larger holes at the periphery, creating different local flow characteristics to balance the air flow velocity across the entire grid surface, thereby improving purging efficiency without requiring complex external flow control devices
Solution Approach 2:
The invention changes the geometric parameters of the grid holes by varying the aperture ratio spatially. The aperture ratio is set to increase from the center toward the periphery, with specific embodiments showing aperture ratios of 30-70% at the center and 70-90% at the periphery. This parameter variation optimizes the air flow velocity distribution to enhance fuel desorption efficiency throughout the adsorbent bed
2Speed
If the aperture ratio is increased at the periphery, then air flow velocity at the periphery is improved for better fuel desorption, but the overall air flow distribution becomes more complex to control
Solution Approach 1:
The grid surface is segmented into multiple zones with different aperture ratios. The grid is divided into a central region with smaller holes (aperture ratio 30-70%) and a peripheral region with larger holes (aperture ratio 70-90%). This segmentation allows independent optimization of hole sizes in different regions to achieve uniform air flow velocity across the entire grid while simplifying the manufacturing process by using standardized hole patterns in each zone
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 grid design enhances purging efficiency by minimizing the difference in air flow speed between the center and periphery, leading to improved desorption rates and overall canister performance.
Implementation Method 1
A spring 17 is fixed on an upper surface of the bottom cap 1c at its portion for closing the first chamber 10, and an upper end of the spring 17 is in contact with the grid 16. Thus, the grid 16 is pushed upward by a biasing force of the spring 17
Implementation Method 2
evaporated fuel generated in a fuel tank or the like is introduced into the first chamber 10 from the charging port 11 through the filter 13 along with air, and is adsorbed by the adsorbents 14 stored inside the first chamber 10
Implementation Method 3
the fuel is desorbed from the adsorbents 14 inside the first chamber 10, and the air that contains the fuel is discharged to the inlet pipe via the purging port 12 and the purge valve (not shown) and combusted in the internal combustion engine
Data Source
AI summary
A grid that includes a plurality of holes perforated therein such that an aperture ratio of the grid increases from the center toward the periphery of the grid. The grid holds adsorbents filled inside a filling chamber of a canister having an opening, and keeps the adsorbents inside the filling chamber.