Evaporative Emissions Control System with Vapor Return
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Solution Overview
Problem
Modern vehicles face challenges in managing hydrocarbon loading of evaporative emissions canisters during refueling events, which affects the size and efficiency of the emission control system.
Innovation Solution
An evaporative emissions control system that includes an evaporative emissions control canister, a fuel vapor feed conduit, a purge valve, a fuel vapor vent valve, and a vapor return system with an eductor pump, which draws fuel vapor through an intermediate bypass conduit to a vapor reservoir for mixing with pressurized fuel and condensing at a diffuser during refueling, reducing the vapor load on the canister.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the evap canister size is increased to handle refueling vapor load, then the hydrocarbon loading capacity is improved, but the device complexity and space requirements worsen
Solution Approach 1:
The system activates the fuel pump and vapor return system before or during the refueling event to proactively manage vapor generation. By anticipating the vapor load from upcoming refueling, the system draws vapor through the bypass conduit and condenses it in the vapor reservoir, preventing the canister from needing to accommodate the full vapor load, thus reducing canister size requirements
Solution Approach 2:
The vapor reservoir acts as an intermediary between the fuel tank and the evap canister. It temporarily stores and condenses fuel vapor that would otherwise go directly to the canister, reducing the canister's hydrocarbon loading burden and allowing for a smaller canister design
2Volume of stationary object
If the evap canister size is reduced to decrease device complexity, then the space requirements are improved, but the hydrocarbon loading capacity worsens
Solution Approach 1:
The vapor return system with the vapor reservoir serves as an intermediary that pre-processes vapor before it reaches the canister. By condensing vapor in the reservoir and returning condensed fuel to the tank, the system reduces the canister's processing burden, enabling smaller canister design without sacrificing overall hydrocarbon management capacity
Solution Approach 2:
The system utilizes phase transition by condensing fuel vapor to liquid in the vapor reservoir through the vapor return system. This phase change removes vapor from the gas phase and returns it to liquid form in the fuel tank, reducing the hydrocarbon load on the canister and enabling smaller canister size while maintaining loading capacity
3Device complexity
If vapor is vented to atmosphere during refueling to simplify the system, then the device complexity is reduced, but the emissions increase
Solution Approach 1:
The vapor return system operates automatically during refueling events, using the fuel pump to draw vapor through the bypass conduit and condense it in the vapor reservoir. This self-activating system manages emissions without requiring complex external controls or manual intervention, reducing emissions while maintaining practical system complexity
Solution Approach 2:
By condensing vapor to liquid phase in the vapor reservoir during refueling, the system converts harmful gaseous emissions into liquid fuel that returns to the tank. This phase transition eliminates emissions without requiring complex aftertreatment systems, achieving emission reduction with manageable device complexity
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 system effectively manages hydrocarbon loading during refueling, reducing the necessary size of the evaporative emissions canister and enhancing the overall efficiency of the emission control system by condensing and reentering fuel vapor into the fuel tank, thereby minimizing emissions.
Implementation Method 1
an eductor pump, which draws fuel vapor through an intermediate bypass conduit to a vapor reservoir for mixing with pressurized fuel
Implementation Method 2
mixing with pressurized fuel flowing from the tapered fuel outlet
Implementation Method 3
condensing at the diffuser
Implementation Method 4
mixing with pressurized fuel flowing from the tapered fuel outlet and condensing at the diffuser
Implementation Method 5
the activated carbon absorbs and stores the fuel vapor
Data Source
AI summary
An evaporative emissions control system comprising an evaporative emissions control (evap) canister. A fuel vapor feed conduit includes a first end fluidically connected to the evap canister, a second end connected to an internal combustion (IC) engine and a purge valve fluidically connected thereto. A fuel vapor conduit includes a first end fluidically connected to the evap canister and a second end configured to extend into a vehicle fuel tank. A fuel vapor vent valve is fluidically connected to the fuel vapor conduit at the second end thereof. A vapor return system includes a fuel pump fluidically connected to the fuel vapor conduit through an intermediate bypass conduit having a first end fluidically connected to an intermediate portion of the fuel vapor conduit and a second end extending into the vehicle fuel tank and in communication with the vapor return system.