Evaporative Emissions System Fuel Tank Pressure Management
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Solution Overview
Problem
Hybrid vehicles with electric motors experience shorter engine run times, limiting evaporative emissions system purging and fuel tank pressure management, which increases emissions and fuel consumption beyond operator requests.
Innovation Solution
Fluidly coupling the fuel tank to the evaporative emissions system and sealing it from the intake manifold and atmosphere, using fuel tank pressure and vacuum to manage purging and vapor storage without active engine modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the engine is forced on to consume vapors, then evaporative emissions are reduced, but fuel consumption increases beyond operator requests
Solution Approach 1:
The fuel tank system serves itself by using its own pressure and vacuum conditions to purge the canister, eliminating the need for active engine control to consume vapors. The system automatically utilizes fuel tank pressure when it exceeds a threshold and fuel tank vacuum when below a threshold, allowing evaporative emissions control without additional fuel consumption.
Solution Approach 2:
The invention converts the harmful effect of fuel tank pressure buildup and vacuum conditions into beneficial purging action. Instead of viewing fuel tank pressure variations as problems to be actively managed by engine operation, the system harnesses these pressure differentials to drive vapor consumption through the canister, turning potential harm into useful emissions control.
2Object-generated harmful factors
If active engine load increase is used to consume vapors efficiently, then evaporative emissions are reduced, but fuel consumption increases
Solution Approach 1:
The system uses the fuel tank's own pressure and vacuum conditions to drive purging operations without requiring active engine load increases. The control system monitors fuel tank pressure and automatically opens the fuel tank valve when pressure exceeds a threshold or when vacuum is present, allowing the fuel tank system to self-regulate vapor consumption without active engine modifications.
Solution Approach 2:
The fuel tank valve acts as an intermediary component that mediates between the fuel tank pressure conditions and the canister purging process. By controlling the valve opening based on fuel tank pressure thresholds, the system enables vapor consumption through pressure differentials rather than requiring active engine load management, thus reducing fuel consumption while maintaining emissions control effectiveness.
3Object-generated harmful factors
If the evap system volume is increased to store more vapors, then vapor breakthrough is reduced, but the system complexity increases
Solution Approach 1:
The invention segments the evaporative emissions control into two distinct operational modes: a first mode where the fuel tank valve is closed and the canister handles vapor storage independently, and a second mode where the fuel tank valve is open and the fuel tank participates in vapor storage and pressure management. This segmentation allows the system to function effectively with existing component sizes without requiring a larger canister, thus avoiding increased system complexity while preventing vapor breakthrough.
Solution Approach 2:
The system dynamically switches between different operational configurations based on fuel tank pressure conditions. The fuel tank valve transitions between closed and open states according to pressure thresholds, creating a dynamic system that adapts to varying conditions. This dynamic operation allows the existing evap system volume to be used more effectively across different operating conditions, preventing vapor breakthrough without requiring permanent system expansion.
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 enhances evaporative emissions system efficiency by utilizing fuel tank pressure and vacuum to maintain system cleanliness and reduce emissions, while minimizing fuel consumption and maintaining customer satisfaction.
Implementation Method 1
fluidly coupling a fuel tank to an evaporative emissions system (evap system) and sealing the evap system from an intake manifold and atmosphere... when a fuel tank pressure is greater than a threshold fuel tank pressure... when a manifold vacuum is not present
Data Source
AI summary
Methods and systems are provided for an evaporative emissions system. In one example, a method includes fluidly coupling the evaporative emissions system to an interior volume of a fuel tank in response to a canister load and a fuel tank pressure. The method further includes scaling the evaporative emissions system from atmosphere and an intake manifold.