Orifice Flow Control Device for Regulating Evaporative Purge in Small Engines
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Solution Overview
Problem
Small internal combustion engines, such as those in lawn mowers and snow blowers, face challenges in reducing evaporative emissions from fuel tanks, which contribute to ozone formation and urban smog, due to vaporization of fuels leading to undesirable emissions during storage and refueling.
Innovation Solution
An evaporative emissions control system that includes an air intake assembly, a fuel tank assembly, and an evaporative emissions control device, with a flow control device, such as an orifice connector or sintered filter, to regulate the purge flow rate of fuel vapors into the engine, minimizing emissions without requiring carburetor recalibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If evaporative emissions control devices are used to reduce fuel vapor emissions, then evaporative emissions are reduced, but the system complexity increases
Solution Approach 1:
The system divides the evaporative emissions control function into separate components: a carbon canister for vapor storage, a flow control device for rate regulation, and integration with the existing air intake assembly. This segmentation allows each component to perform its specific function independently, reducing overall system complexity while maintaining effective emissions control.
Solution Approach 2:
The flow control device acts as an intermediary component between the carbon canister and the air intake assembly, mediating the purge flow rate of fuel vapors. This intermediary element enables precise control of emissions without requiring complex electronic control systems or modifications to the carburetor, thus reducing system complexity while achieving emissions reduction goals.
2Object-generated harmful factors
If purge flow rate is increased to reduce emissions buildup, then emissions control improves, but engine performance may be affected
Solution Approach 1:
The flow control device enables dynamic control of the purge flow rate, allowing the system to adjust the amount of fuel vapor introduced into the engine based on operating conditions. This dynamic adjustment ensures optimal emissions control while maintaining engine performance across varying load and temperature conditions, preventing both emissions buildup and performance degradation.
Solution Approach 2:
The system controls the purge flow rate parameter to optimize both emissions control and engine performance. By adjusting this single parameter through the flow control device, the system achieves effective emissions reduction without introducing excessive fuel vapors that could affect carburetor mixing or engine operation, thus maintaining reliability.
3Adaptability or versatility
If different carbon canister sizes are used to accommodate various fuel tank capacities, then adaptability improves, but manufacturing precision requirements increase
Solution Approach 1:
The flow control device is designed as a universal component that works with carbon canisters of various sizes and designs. By placing the flow control device in the purge line rather than integrating it into the carburetor or canister, the system achieves multi-functionality and adaptability across different engine and fuel tank configurations without requiring precision manufacturing variations in the control device itself.
Solution Approach 2:
The flow control device uses a simple orifice structure that can be easily manufactured with standard tolerances. This approach accepts that the orifice may require replacement or adjustment rather than achieving high precision manufacturing, thereby reducing manufacturing precision requirements while maintaining adaptability to different carbon canister sizes through a cost-effective, easily replaceable component.
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
Effectively reduces evaporative emissions by controlling the purge flow rate of fuel vapors, maintaining engine performance across varying carbon canister sizes and designs without the need for costly recalibration, thus addressing environmental concerns and compliance with regulations like those in California for Small Off Road Engines.
Implementation Method 1
The flow control device further includes at least one of an orifice and a passageway, at least one of the orifice and the passageway sized in relation to the evaporative emissions control device and the fuel tank assembly
Implementation Method 2
the flow control device can be a sintered filter having a plurality of passageways formed therein
Implementation Method 3
The liquid fuel stored within the housing is additionally capable of evaporation producing fuel vapors comprising volatile organic compounds (VOC)
Data Source
AI summary
A system and method of controlling/adjusting purge flow rate in an internal combustion engine is disclosed. The system includes an air intake assembly, a fuel tank assembly and an evaporative emissions control device such as a carbon canister in operational association with each other. Fuel vapors from the fuel tank assembly flow into the evaporative emissions control device for adsorption. The adsorbed fuel vapors from the evaporative emissions control device are recovered, at least in part due to pressure differentials, and actively purged into the internal combustion engine. The purge flow rate from the evaporative emissions control device is controlled/adjusted by a flow control device, the flow control device that is at least indirectly connected to the evaporative emissions control device and the air intake assembly. In one aspect, the flow control device can comprise an orifice device, such as, a connector device having at least one orifice for regulating purge flow rate. In another aspect, the flow control device can comprise a filter device for cleaning the intake and/or purged air in addition to regulating the purge flow rate.