ORVR Valve Control for Fuel Spit-Back Prevention
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Solution Overview
Problem
Existing onboard refueling vapor recovery (ORVR) systems face issues with fuel spit-back during refueling, where closing the flow path between the fuel tank and the purge canister can result in liquid fuel ejection, posing safety and environmental concerns.
Innovation Solution
An electronic solenoid valve is actuated by a refueling event indicator and controlled based on fuel level and vapor pressure sensors to precisely manage the opening and closing of the flow path, preventing extended closure and thus minimizing spit-back by venting fuel vapors efficiently during pressure decay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the flow path between the fuel tank and the purge canister is closed during refueling, then fuel vapor recovery is improved, but liquid fuel spit-back occurs
Solution Approach 1:
The patent employs a dynamic control strategy where the ORVR valve switching frequency is adjusted based on real-time pressure differential measurements. The valve transitions from frequent switching at refueling start to less frequent switching as refueling progresses, creating a dynamic balance between vapor recovery and preventing liquid fuel carryover to the purge canister
Solution Approach 2:
The system uses pressure differential sensors to continuously monitor the pressure difference between the fuel tank and purge canister, feeding this information back to the control unit. The control unit adjusts the ORVR valve switching pattern based on this feedback, optimizing the balance between vapor recovery efficiency and preventing liquid fuel spit-back
2Reliability
If the ORVR valve is kept closed to prevent liquid fuel carryover, then safety is improved, but vapor recovery efficiency deteriorates
Solution Approach 1:
The system implements periodic switching of the ORVR valve between open and closed positions. This periodic action allows the valve to periodically permit vapor flow while also periodically preventing liquid fuel carryover, achieving both safety and vapor recovery efficiency through time-based modulation rather than static positioning
3Reliability
If the valve responds quickly to slosh and vibration conditions, then carryover prevention is improved, but mechanical durability deteriorates
Solution Approach 1:
The patent replaces mechanical vibration-sensitive valves with an electronically controlled ORVR valve system. The electronic control unit processes signals from vibration and slosh sensors to actuate the valve, eliminating the need for purely mechanical response mechanisms and thereby improving both response speed and mechanical durability
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 method effectively prevents fuel spit-back by controlling the electronic valve to open and close the flow path in response to pressure changes, ensuring emissions compliance and safety by managing pressure build-up and vapor venting.
Implementation Method 1
an ORVR valve (40) in the flow path and actuating the ORVR valve (40) in accordance with the output of the fueling event sensor to selectively open and close the flow path
Implementation Method 2
monitoring the pressure within the fuel tank and, in response to the pressure monitoring, actuating the ORVR valve to open and close the flow path
Implementation Method 3
The purge canister typically includes a charcoal element to capture hydrocarbons while releasing filtered vapors into the atmosphere
Data Source
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AI summary
A method for recovering vapor during an onboard refueling operation comprising the steps of: providing a flow path (28) between a fuel tank (12) and a purge canister (30); providing a valve (40) in said flow path (28); providing a fuel level sensor (20) for indicating the level of fuel in the fuel tank (12), and a vapor pressure sensor (48) for indicating the pressure of the fuel vapor in the fuel tank (12), and actuating the valve (40) to selectively open and close the flow path (28) in response to signals received from the fuel level sensor (20) and the vapor pressure sensor (48).