Fuel Tank Venting Valve With Diaphragm Pressure Regulation
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Solution Overview
Problem
Existing fuel tank venting systems face challenges in efficiently regulating the discharge of pressurized fuel vapor and admission of outside air, leading to inefficient pressure control and potential contamination issues.
Innovation Solution
A pressure-controlled valve with a deformable diaphragm and an electronic bleed controller that manages two vapor flow paths, allowing for precise regulation of fuel vapor flow to a fuel-vapor recovery canister, ensuring efficient pressure control and contaminant trapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pressure-controlled valve is used to regulate large volume pressurized fuel vapor flow, then pressure control efficiency is improved, but the valve may fail to respond precisely to pressure changes due to the large force required to move it
Solution Approach 1:
A diaphragm is introduced as an intermediary element between the pressure control mechanism and the valve stem. The diaphragm converts small pressure differential forces into sufficient mechanical force to actuate the valve, enabling precise pressure control while maintaining the capability to regulate large vapor flows. The diaphragm acts as a force amplifier that translates minor pressure changes into significant valve actuation forces.
Solution Approach 2:
The traditional direct mechanical linkage between the valve actuator and valve stem is replaced with a pneumatic-hydraulic system using the diaphragm. Instead of using a large mechanical force directly on the valve stem, the system uses pressure differential across the diaphragm to generate the necessary force, substituting a mechanical force application with a pressure-based actuation mechanism that offers finer control.
2Loss of substance
If the pressure-controlled valve remains closed to prevent vapor loss, then fuel vapor containment is improved, but pressure buildup in the fuel tank may cause safety issues
Solution Approach 1:
The system implements a feedback mechanism where the pressure differential across the diaphragm continuously monitors tank pressure conditions. When tank pressure exceeds the spring bias force, the pressure differential automatically actuates the valve to open, releasing excess pressure. This closed-loop feedback ensures the valve responds dynamically to pressure changes, maintaining safe pressure levels while minimizing unnecessary vapor discharge.
Solution Approach 2:
The pressure control system is designed to be self-regulating without requiring external control inputs. The spring-diaphragm assembly automatically balances the forces of tank pressure and spring bias, causing the valve to open or close based solely on the pressure differential. This self-service mechanism ensures continuous pressure management while preventing both vapor loss and dangerous pressure buildup.
3Device complexity
If a simple vent valve design is used, then device complexity is reduced, but the ability to precisely control vapor flow and pressure is compromised
Solution Approach 1:
The invention merges multiple functions into a single integrated valve assembly. The pressure control valve combines the pressure sensing diaphragm, the flow control valve stem, and the discharge pathway into one unified component. This integration achieves precise vapor flow control and pressure management without requiring separate sensors, actuators, and control mechanisms, thereby limiting the increase in device complexity while substantially improving control capability.
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 enables efficient regulation of large volumes of pressurized fuel vapor flow while preventing contamination, effectively managing pressure and ensuring clean air discharge, thereby improving the overall performance of the fuel tank venting system.
Implementation Method 1
A deformable diaphragm that flexes in response to a pressure differential being applied to opposing sides of the pressure-controlled valve to move the pressure-controlled valve from the closed position to the opened position
Implementation Method 2
A deformable diaphragm that flexes in response to a pressure differential
Implementation Method 3
Pressurized fuel vapor discharged into the vent apparatus from the fuel tank can flow through the valve-pressurization feed passageway into a region above the pressure-controlled valve and can apply a force to a topside of the pressure-controlled valve that cause the valve to move to a closed position
Implementation Method 4
A bias spring may be included in the electronic bleed controller is configured to encourage the pressure-controlled valve to move toward the normally closed position
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A venting apparatus is provided for regulating discharge of fuel vapor from a fuel tank and admission of outside air into the fuel tank.