Fuel Vapor Canister Vent Valve Control for Hydrocarbon Breakthrough
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Solution Overview
Problem
In hot climates or after prolonged driving, the fuel vapor canister's temperature increases, reducing its adsorption capacity, leading to hydrocarbon breakthrough during refueling events, which can result in emissions into the atmosphere, and existing solutions like secondary trap canisters may restrict vapor flow, limiting refueling rates and causing prolonged depressurization.
Innovation Solution
A method that involves detecting hydrocarbon breakthrough during refueling using a sensor and actuating a canister vent valve to restrict fuel vapor flow, increasing fuel tank pressure and triggering an automatic refueling dispenser shutoff, thereby preventing significant hydrocarbon emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a trap canister is added downstream to capture breakthrough hydrocarbons, then hydrocarbon emissions are reduced, but vapor flow is restricted and refueling rate is limited
Solution Approach 1:
The system proactively monitors canister temperature and predicts breakthrough risk before it occurs. By detecting temperature thresholds and pre-restricting vapor flow when breakthrough is anticipated, the system prevents emissions without requiring a trap canister that would continuously restrict flow.
Solution Approach 2:
The patent replaces the mechanical trap canister system with an electronic control system using temperature sensors, microcontrollers, and solenoid valves. This substitution allows dynamic control of vapor flow based on real-time conditions, avoiding the continuous flow restriction inherent in trap canister designs.
2Temperature
If the canister temperature increases in hot climates or after prolonged driving, then adsorption capacity decreases, but the system continues to operate without emission controls
Solution Approach 1:
The system uses temperature sensors to continuously monitor canister temperature and feeds this information back to a microcontroller. Based on the feedback, the controller dynamically adjusts vapor flow restriction to maintain adsorption effectiveness across varying temperature conditions, preventing breakthrough when the canister is hot.
Solution Approach 2:
The system changes the operational parameters of the vapor recovery system based on canister temperature. When temperature increases indicating reduced adsorption capacity, the system modifies vapor flow rates and timing to compensate, maintaining effective hydrocarbon capture despite temperature-induced capacity changes.
3Object-generated harmful factors
If vapor flow is restricted to prevent hydrocarbon breakthrough, then emissions are reduced, but fuel tank pressure increases and refueling is terminated
Solution Approach 1:
The system uses periodic purging cycles where the canister is temporarily disconnected from the vapor path and purged with engine intake vacuum. This periodic action resets the canister's adsorption capacity, allowing extended refueling operations without continuous flow restriction, thereby maintaining both emission control and refueling quantity.
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 effectively limits hydrocarbon emissions during refueling, allowing vehicles to fill fuel without increasing surface hydrocarbon concentrations, thus reducing ground ozone levels on hot days, while maintaining refueling efficiency.
Implementation Method 1
vaporized hydrocarbons (HCs) from a fuel tank may be stored in a fuel vapor canister packed with an activated carbon adsorbent which adsorbs and stores the vapors
Implementation Method 2
Adsorption of fuel vapor to activated carbon is an exothermic reaction. A hot canister thus has a lower adsorption capacity than does a cool canister
Data Source
AI summary
A method is presented, comprising, during a first condition, including an active refueling event, receiving an indication of hydrocarbon breakthrough from the fuel vapor canister; and restricting flow of fuel vapor through a fuel vapor canister vent pathway responsive to the indication of hydrocarbon breakthrough. Restricting the fuel vapor canister vent pathway will cause fuel tank pressure to increase, thus triggering an automatic shutoff of a refueling dispenser. In this way, the refueling event may be terminated without releasing significant quantities of hydrocarbons into the atmosphere.