Fuel Tank Pressure Control via Segmented Vapor Path
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Solution Overview
Problem
Conventional methods for controlling internal pressure in fuel tanks, such as those using porous materials like activated carbon or zeolite, face challenges in preventing fuel component loss due to reduced engine stop times and negative pressure in hybrid vehicles, leading to inefficient desorption and potential fuel waste.
Innovation Solution
An apparatus utilizing an adsorption/desorption device that selectively adsorbs and desorbs air components within the fuel tank, not communicated with external air, to manage internal pressure through a pressure swing adsorption process, reducing fuel loss and tank damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a canister containing porous material is used to exhaust vapor and capture fuel components, then fuel components are captured and only air components are exhausted, but the time required for desorption becomes excessively long due to the large amount of desorbed air needed (300 to 600 times the canister capacity)
Solution Approach 1:
The invention divides the vapor exhaust system into two separate paths: a first vapor exhaust path with a canister for capturing fuel components, and a second vapor exhaust path with a fuel vapor separator for directly exhausting air components. This segmentation allows air components to be quickly removed without requiring lengthy desorption of a large canister, thereby reducing desorption time while preventing fuel component loss.
Solution Approach 2:
The fuel vapor separator acts as an intermediary device that selectively allows air components to pass through while blocking fuel components. This intermediary enables the direct exhaust of air components without requiring them to be desorbed from the canister, significantly reducing the desorption time requirement.
2Loss of substance
If the canister capacity is increased to capture more fuel components, then fuel component capture is improved, but the time and amount of desorption required increases proportionally
Solution Approach 1:
By segmenting the vapor exhaust into two paths, the system can use a smaller canister capacity while still effectively capturing fuel components. The fuel vapor separator handles the bulk air component removal, improving desorption efficiency by reducing the total amount of air that needs to be desorbed from the canister.
3Productivity
If a fuel vapor separator with porous material is used to exhaust vapor to atmosphere, then air components can be exhausted while maintaining low canister capacity, but the porous material may not reliably block all fuel components due to non-uniform pore diameters
Solution Approach 1:
The invention uses a fuel vapor separator filled with porous material having specific pore diameter characteristics that allow air components to pass through while blocking fuel components. The porous material is selected and positioned to provide reliable separation, preventing fuel component loss while maintaining fast desorption speed through the separator.
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
Effectively controls internal pressure without fuel component escape, reducing fuel loss and allowing for a lighter, cheaper fuel tank design by selectively managing air components, and enhancing desorption speed through a circulation channel configuration.
Implementation Method 1
an adsorption/desorption device for selectively adsorbing and/or desorbing air components contained in vapor
Implementation Method 2
utilizing an adsorption/desorption device that selectively adsorbs and desorbs air components within the fuel tank
Data Source
AI summary
An adsorption/desorption device is communicated with an upper space of a fuel tank via a vapor passage. The adsorption/desorption device is configured to selectively adsorb or desorb air components contained in vapor. The adsorption/desorption device and the vapor passage are not communicated to the external atmosphere. The fuel tank is provided with a pressure detecting device for detecting the internal pressure of the fuel tank. A pressure regulating device is provided to the vapor passage for controlling and maintaining the pressure applied to the adsorption/desorption device. When the internal pressure of the fuel tank is higher than the atmospheric pressure, the internal pressure of the fuel tank is pressure-fed to the side of the adsorption/desorption device via the pressure regulating device until the internal pressure of the fuel tank becomes in equilibrium with the atmospheric pressure. When the internal pressure of the fuel tank is lower than the atmospheric pressure, vapor is pressure-fed to the side of the fuel tank via the pressure regulating device until the internal pressure of the fuel tank becomes in equilibrium with the atmospheric pressure.