Fuel Vapor Control Valve Pressure Threshold Design
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Solution Overview
Problem
Existing fuel vapor control valves in vehicles fail to effectively manage pressure changes in fuel tanks, leading to unsteady fuel supply, potential tank deformation, and fuel leakage, while also allowing unnecessary fuel vapor evacuation, which increases fuel consumption and environmental impact.
Innovation Solution
A fuel vapor control valve with a diaphragm-based design that remains closed during filling, vents the tank to prevent pressure rise, allows air flow during pressure drops, and includes a one-way valve to prevent vapor flow when pressure in the piping is lower than atmospheric pressure, ensuring controlled vapor transfer between the fuel tank and the vapor recovery device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel vapor is continuously evacuated from the fuel tank to the vapor recovery device, then fuel vapor pressure is reduced, but unnecessary fuel vapor evacuation occurs increasing fuel consumption
Solution Approach 1:
The valve changes its flow state based on pressure parameter thresholds. It remains closed when pressure is below the first threshold value, and opens to evacuate vapor only when pressure exceeds the first threshold, thereby controlling vapor evacuation based on pressure conditions to prevent unnecessary fuel loss
Solution Approach 2:
The valve automatically responds to pressure changes in the fuel tank system without external control. The pressure-responsive mechanism self-regulates vapor evacuation by opening or closing based on the pressure differential between the fuel tank and atmosphere, eliminating the need for external actuators or complex control systems
2Reliability
If pressure-responsive valves open at high pressure to evacuate vapor, then vapor pressure control is improved, but fuel droplets may flow towards the vapor recovery system
Solution Approach 1:
The valve is designed with a specific pressure threshold that must be exceeded to open the valve. This threshold is set to ensure that only significant pressure builds-up (indicating true vapor accumulation rather than liquid presence) will trigger vapor evacuation, thereby preventing fuel droplet contamination while maintaining effective vapor pressure control
3Ease of operation
If the control valve remains closed during filling, then spontaneous shut-off is achieved, but pressure changes within the fuel tank may cause tank deformation or damage
Solution Approach 1:
The valve incorporates a pressure threshold mechanism that automatically opens when pressure exceeds a predetermined level during fuel filling. This allows the system to maintain closure for spontaneous shut-off functionality while providing automatic pressure relief to prevent tank deformation or damage when excessive pressure occurs
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 effectively manages pressure changes, prevents fuel tank deformation, reduces fuel consumption, and minimizes fuel vapor escape to the atmosphere by controlling vapor flow based on pressure thresholds, ensuring efficient and environmentally friendly operation.
Implementation Method 1
a first valve controlled passage admitting fuel vapor flow in a direction from said inlet port to said outlet port only when pressure within the fuel tank exceeds a threshold
Implementation Method 2
said diaphragm being normally biased into a closed position sealing said first valve controlled passage at a predetermined force
Implementation Method 3
a second valve controlled passage for admitting vapor flow in an opposite direction from said outlet port to said inlet port only when pressure within the fuel tank drops below pressure at the fuel vapor recovery device
Data Source
AI summary
A fuel vapor control valve comprising a housing fitted with an inlet port connectable to a fuel tank and an outlet port connectable to a fuel vapor recovery device. The inlet port and the outlet port are in flow communication via a first valve controlled passage admitting fuel vapor flow in a direction from the inlet port to the outlet port only when pressure within the fuel tank exceeds a threshold. A second valve controlled passage admits vapor flow in an opposite direction from the outlet port to the inlet port only when pressure within the fuel tank drops below pressure at the fuel vapor recovery device.