Hydrocarbon Trap Purging via Fuel Vapor Canister
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Solution Overview
Problem
In plug-in hybrid electric vehicles, the limited engine run-time restricts the purging of hydrocarbon (HC) traps, leading to fuel economy efficiency penalties and increased hydrocarbon breakthrough emissions.
Innovation Solution
A method is implemented where fuel vapors from the HC trap are passively purged into a fuel vapor canister using naturally occurring diurnal temperature changes, allowing the canister to store and later purge the vapors when the engine is running, thereby reducing HC trap loading and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine run-time is extended to purge the HC trap, then the HC trap can be cleaned effectively, but fuel economy efficiency deteriorates
Solution Approach 1:
The patent applies preliminary action by using the fuel vapor canister to store hydrocarbons during engine-off conditions before the engine needs to purge the HC trap. This pre-storage capability allows the HC trap to be cleaned without forcing the engine to run longer, thus maintaining fuel economy while ensuring reliable HC trap purging when needed.
2Object-generated harmful factors
If the HC trap capacity is increased to store more fuel vapors, then emissions are reduced, but the trap loading time increases leading to more frequent purging requirements
Solution Approach 1:
The patent introduces an intermediary component - the fuel vapor canister - that acts as a mediator between the HC trap and the atmosphere. This canister temporarily stores hydrocarbons that would otherwise be emitted, allowing the HC trap to maintain smaller capacity while still achieving effective emissions control through the two-stage storage system.
3Object-generated harmful factors
If the engine is forced to run to purge the HC trap, then hydrocarbon breakthrough emissions are reduced, but fuel economy efficiency penalty increases
Solution Approach 1:
The patent converts the harmful effect of engine-off conditions (which prevent HC trap purging) into a beneficial opportunity. During engine-off conditions, the system uses the fuel vapor canister to capture and store hydrocarbons from the HC trap, transforming a period when emissions control cannot be actively managed into a productive storage phase that reduces the need for fuel-consuming purging operations.
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 hydrocarbon breakthrough in the HC trap, decreases emissions, and enhances fuel economy by utilizing the fuel vapor canister's larger storage capacity during engine-off conditions.
Implementation Method 1
a fuel vapor canister may be used to adsorb fuel vapors from an HC trap in an engine intake
Implementation Method 2
vacuum generated in a fuel tank via naturally occurring diurnal temperature changes may be used to passively purge an HC trap
Data Source
AI summary
Methods and systems for passively purging a hydrocarbon trap in an engine intake in a vehicle are disclosed. In one example approach, a method comprises, in response to an ambient temperature decrease during an engine off condition while a fuel tank is sealed from atmosphere, delivering fuel stored in a hydrocarbon trap in an intake of the engine to a fuel vapor canister coupled to the fuel tank in an emission control system.