Fuel Vapor Canister Purge Buffer Zone Design
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Solution Overview
Problem
Existing fuel vapor storage and recovery apparatuses, such as carbon canisters, suffer from the creation of 'carbon dead zones' during purging, leading to reduced adsorption capacity and increased diurnal bleeding losses due to incomplete regeneration and direct hydrocarbon bypass.
Innovation Solution
Incorporating a purge buffer zone within the main vapor storage compartment, arranged between first and second fuel vapor distribution chambers, ensures even gas flow and prevents the formation of dead zones by requiring hydrocarbon-laden gas to pass through the adsorbent material before reaching the purge buffer zone, thus maximizing adsorption efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a purge buffer is implemented within the carbon bed to eliminate hydrocarbon peaks, then engine intake mixture control is improved, but a carbon dead zone is created reducing adsorption capacity
Solution Approach 1:
The carbon bed is segmented into a main adsorption zone and a separate purge buffer zone located at the downstream end. This segmentation allows the purge buffer to handle hydrocarbon peaks during purging without creating a dead zone within the main adsorption area, thereby maintaining adsorption capacity while ensuring reliable engine intake mixture control.
Solution Approach 2:
The purge buffer function is extracted from the main carbon bed and placed in a separate downstream location. This extraction eliminates the conflict between needing a purge buffer for engine control and avoiding dead zones for adsorption capacity, as the buffer operates independently at the exit端 of the carbon bed.
2Reliability
If the transfer conduit extends into the carbon bed to create a primary air inlet, then hydrocarbon-laden gas is forced through the carbon bed, but a carbon dead zone is created leading to reduced working capacity
Solution Approach 1:
The primary air inlet is extracted from the carbon bed interior and relocated to the downstream end outside the carbon bed. This allows hydrocarbon-laden gas to be drawn through the entire carbon bed length for effective filtration while avoiding the creation of a dead zone within the adsorbent material, thereby maintaining full working capacity.
Solution Approach 2:
A bypass passage acts as an intermediary, allowing atmospheric air to enter at the downstream end and flow through the carbon bed in reverse direction during purging. This mediator enables hydrocarbon removal without requiring the transfer conduit to penetrate into the carbon bed, thus preventing dead zone formation.
3Productivity
If ambient air is drawn through the atmospheric vent port during purging, then the carbon bed is regenerated, but hydrocarbons may bypass the adsorbent material directly to the engine air intake line
Solution Approach 1:
The purge buffer zone is positioned at the downstream end of the carbon bed to intercept and buffer hydrocarbon-laden air before it reaches the engine air intake line. This preliminary action ensures that even during regeneration when ambient air is drawn through the vent port, hydrocarbons are properly managed and delivered to the engine in a controlled manner, preventing direct bypass.
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 design minimizes the formation of dead zones, enhances the regeneration process, and maintains the adsorption capacity of the carbon canister, reducing diurnal bleeding losses and ensuring efficient fuel vapor recovery.
Implementation Method 1
High-surface area granular activated carbon material are widely used and temporarily adsorb the fuel vapor
Implementation Method 2
an engine air intake line draws atmospheric air backwards through the carbon canister, so that hydrocarbons are delivered to the engine for burning-off
Data Source
Figure 1
Figure 2~3
AI summary
The invention refers to a fuel vapor storage and recovery apparatus (1) comprising at least one main vapor storage compartment (3) filled with an adsorbent material, at least one vapor inlet port (7), at least one atmospheric vent port (8) and at least one purge port (9), said vapor inlet port (7) being connectable to a fuel tank venting line and said purge port (9) being connectable to an engine air intake line, wherein said main vapor storage compartment (3) comprises a purge buffer zone (14) as well as first and second fuel vapor distribution chambers (10, 24) not filled with an adsorbent material. Said first fuel vapor distribution chamber is arranged upstream said purge buffer zone (14) and communicates with said fuel vapor inlet port (7). Said second fuel vapor distribution chamber (24) is arranged downstream said purge buffer zone and communicates with said purge port (9).