Delta Pressure Sensor for Fuel Tank Venting Control
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Solution Overview
Problem
In non-integrated refueling canister only systems (NIRCOS), the use of two pressure sensors increases costs and complexity, leading to potential degradation points, and results in prolonged fuel tank venting duration due to lack of feedback on fuel tank relative pressure when the tank is vented, delaying refueling and overloading the fuel vapor storage canister.
Innovation Solution
A method utilizing a single delta pressure sensor to determine and adjust the pulsing of the fuel tank isolation valve (FTIV) based on differential pressure measurements, allowing for efficient venting by maintaining feedback on fuel tank pressure even when vented, by fluidically coupling the sensor across the FTIV and using the differential pressure to indicate relative pressures and adjust pulsing rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two pressure sensors are used in NIRCOS to monitor fuel system and evaporative emissions system, then system reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines two separate pressure sensors into a single delta pressure sensor that measures the pressure difference between the fuel system and evaporative emissions system. This merging approach maintains the ability to monitor both systems while reducing component count, complexity, and cost.
Solution Approach 2:
The delta pressure sensor serves multiple functions: it monitors fuel system pressure, monitors evaporative emissions system pressure, and detects degradation in both systems. This multi-functionality eliminates the need for separate sensors while maintaining comprehensive monitoring capability.
2Measurement precision
If two pressure sensors are used in NIRCOS, then measurement precision is improved, but loss of time and refueling delay occur
Solution Approach 1:
The delta pressure sensor provides continuous feedback on the pressure difference between the fuel tank and evaporative emissions system during venting operations. This feedback enables the control system to adjust the fuel tank isolation valve pulsing in real-time, ensuring efficient venting while preventing over-venting that would delay refueling.
Solution Approach 2:
The system dynamically adjusts the fuel tank isolation valve pulsing based on real-time delta pressure measurements. The valve is pulsed open and closed in response to depressurization conditions, with the pulsing characteristics adjusted based on the measured differential pressure, enabling adaptive control that optimizes venting duration.
3Stress or pressure
If fuel tank is vented for prolonged duration, then fuel system depressurization is achieved, but fuel vapor storage canister becomes overloaded
Solution Approach 1:
The delta pressure sensor provides feedback on the pressure difference during venting, enabling the control system to monitor when the fuel tank has been sufficiently depressurized. This feedback prevents prolonged venting that would overload the fuel vapor storage canister with excessive fuel vapors.
Solution Approach 2:
The fuel tank isolation valve is pulsed open and closed periodically during venting operations, with the pulsing adjusted based on delta pressure measurements. This periodic action with feedback control achieves thorough depressurization while limiting total venting duration to prevent canister overload.
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 approach reduces system costs and complexity, ensures efficient fuel tank venting, and prevents overloading of the fuel vapor storage canister by maintaining accurate feedback on fuel tank pressure during venting, thereby optimizing refueling operations.
Implementation Method 1
a single delta pressure sensor coupled across the FTIV. The delta pressure sensor may output a signal corresponding to a pressure difference (e.g., a differential pressure) between the evaporative emissions system and the fuel system
Implementation Method 2
venting a fuel tank by pulsing a fuel tank isolation valve (FTIV) open and closed in response to a depressurization condition determined based on a differential pressure
Data Source
AI summary
Methods and systems are provided for including a single pressure sensor in an evaporative emissions system and fuel system. In one example, a method may include venting a fuel tank of the fuel system, which is isolated from the evaporative emissions system by a fuel tank isolation valve (FTIV), in response to a depressurization condition determined based on a differential pressure measured by a delta pressure sensor coupled across the FTIV. The venting may include pulsing the FTIV open and closed and may further include adjusting the pulsing responsive to the differential pressure measured while the FTIV is closed and independent of the differential pressure measured while the FTIV is open.