Pre-chamber Igniter for Reducing Vehicle Evaporative Emissions
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Solution Overview
Problem
The existing fuel vapor emissions control systems using carbon-filled fuel vapor storage canisters face challenges in efficiently purging fuel vapors, leading to potential atmospheric release when the vapor generation rate exceeds purging capacity, resulting in increased evaporative emissions and reduced combustion stability.
Innovation Solution
Increasing the amount of fuel supplied to an igniter with a pre-chamber during canister purging, allowing for improved combustion stability and enhanced flow rates of hydrocarbons, thereby accelerating the emptying of the canister and reducing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the purging rate of fuel vapors from the carbon filled canister is increased, then the time to empty the canister is reduced, but combustion stability deteriorates due to excessive fuel vapor flow rates
Solution Approach 1:
The combustion chamber is segmented into a pre-chamber and a main chamber. The pre-chamber receives concentrated fuel vapor from the canister and pre-combusts it, then transfers the ignited mixture to the main chamber. This segmentation allows high fuel vapor flow rates during purging while maintaining combustion stability through the staged combustion process.
Solution Approach 2:
The pre-chamber acts as an intermediary between the fuel vapor source (canister) and the main combustion chamber. It conditions the fuel vapor by pre-mixing and pre-combusting it before introducing it to the main chamber, thereby mediating the transition from high-flow purging conditions to stable combustion.
2Stability of the object's composition
If the amount of fuel supplied to the igniter is increased during canister purging, then combustion stability is improved, but the efficiency of hydrocarbon breakdown decreases
Solution Approach 1:
The problematic element (excessive fuel supply to main chamber during purging) is extracted and relocated to the pre-chamber. By concentrating fuel supply in the pre-chamber rather than the main combustion chamber, the system maintains combustion stability where needed while preserving hydrocarbon breakdown efficiency in the main chamber.
Solution Approach 2:
Different fuel supply strategies are applied to different locations: concentrated fuel supply to the pre-chamber for stability, and optimized fuel supply to the main chamber for efficient hydrocarbon breakdown. This local differentiation resolves the contradiction between stability and efficiency.
3Object-generated harmful factors
If the fuel vapor flow rate through the carbon filled canister is increased, then evaporative emissions are reduced, but combustion stability deteriorates
Solution Approach 1:
The system segments the fuel vapor processing into two stages: high-flow purging through the pre-chamber to reduce emissions, and stable combustion in the main chamber. This allows high fuel vapor flow rates that reduce evaporative emissions while maintaining combustion stability through the pre-chamber's conditioning作用.
Solution Approach 2:
The pre-chamber performs preliminary action by pre-mixing and pre-combusting fuel vapors before they enter the main chamber. This preliminary conditioning enables the system to handle high fuel vapor flow rates from rapid canister purging while ensuring stable combustion in the main chamber.
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 the time required to purge the canister, improves combustion stability during fuel vapor purging, and decreases evaporative emissions by increasing fuel vapor flow, especially during hydrocarbon breakthrough conditions.
Implementation Method 1
The igniter may include a pre-chamber. By increasing an amount of fuel that is supplied to an igniter that includes a pre-chamber in response to purging of fuel vapors from a carbon filled canister
Implementation Method 2
A vehicle may include a fuel vapor emissions control system that utilizes a carbon filled fuel vapor storage canister. The carbon filled fuel vapor storage canister may store fuel vapors when liquid fuel in a fuel tank is heated via diurnal heating
Data Source
AI summary
Methods and systems are presented for improving operation of an engine that includes an evaporative emissions system. In one example, the methods and systems adjust an amount of fuel that is delivered to a pre-chamber of an igniter in response to purging fuel vapors and/or an indication of hydrocarbon breakthrough of a carbon filled fuel vapor storage canister.