Fuel Tank Isolation Valve Control for Hybrid Vehicles
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Solution Overview
Problem
In hybrid electric vehicles and plug-in hybrid electric vehicles, the continuous powering of fuel tank isolation valves during refueling events leads to unnecessary power consumption and reduced fuel economy, especially when fuel is not being added to the tank or is added at a low rate.
Innovation Solution
A method where the fuel tank isolation valve is actuated to vent the tank during refueling, and then discontinued if the tank pressure remains below a threshold for a predetermined time, indicating low fuel flow, to conserve power, and re-actuated when pressure increases, ensuring efficient venting only when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel tank isolation valve is continuously powered during refueling events, then the fuel tank is vented to reduce pressure build-up, but power consumption increases and fuel economy decreases
Solution Approach 1:
The fuel tank isolation valve is transitioned from a static continuously-powered state to a dynamic state where it is activated only when refueling conditions are detected. The control system monitors refueling status and selectively actuates the valve, making the system adaptive to actual operating conditions rather than maintaining a fixed operational state.
Solution Approach 2:
The system uses the refueling event detection mechanism and existing pressure monitoring infrastructure to automatically control the isolation valve. The control system leverages available sensors and signals (refueling event detection, pressure sensors) to self-regulate valve operation without requiring continuous external intervention or power.
2Reliability
If the fuel tank isolation valve is continuously powered during refueling events, then the fuel tank is vented to prevent fuel pump nozzle shut-offs, but fuel economy is reduced
Solution Approach 1:
The valve operation is made dynamic and conditional rather than continuous. The control system evaluates refueling status in real-time and activates the valve only during actual refueling operations, creating an adaptive system that responds to changing conditions rather than maintaining constant operation.
Solution Approach 2:
The control system incorporates feedback from refueling event detection and pressure monitoring to regulate valve operation. By continuously monitoring system state and adjusting valve actuation accordingly, the system ensures proper venting during refueling while avoiding unnecessary operation during idle periods.
3Reliability
If the fuel tank isolation valve is actuated during low fuel flow conditions, then the fuel tank is vented, but power is consumed unnecessarily
Solution Approach 1:
The system transitions from static continuous valve operation to dynamic conditional operation. By monitoring refueling event status and pressure conditions, the control system adapts valve actuation to match actual system needs, activating the valve only when refueling is occurring or pressure management is required.
Solution Approach 2:
The control system utilizes existing pressure sensors and refueling event detection capabilities to automatically determine when valve actuation is necessary. The system serves itself by leveraging available monitoring infrastructure to make intelligent decisions about valve operation without requiring additional sensors or continuous external control.
Data Source
AI summary
Methods and systems for controlling a fuel tank isolation valve coupled to a fuel tank in a vehicle are disclosed. In one example approach, a method comprises, in response to a refuel request, actuating a fuel tank isolation valve to vent a fuel tank for refueling; and, in response to a pressure in the fuel tank below a threshold pressure after a predetermined time duration, discontinuing actuation of the fuel tank isolation valve to seal the fuel tank.