Centrifugal Separator for Two-Stroke Engine Air Intake
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Solution Overview
Problem
Two-stroke internal combustion engines with stratified charge systems face difficulties in cold starting due to the need for a rich fuel-air mixture and are bulky due to the long air duct and additional air filtration requirements, making them less suitable for weight and dimension-sensitive applications like hand-held power tools.
Innovation Solution
A centrifugal separator is used to clean air by separating lubricating oil and fuel from the air stream before it enters the combustion chamber, allowing for a single air filter and a short air duct, enabling efficient production of a lean fuel-air mixture and improving engine compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an extra air shutter and long air duct are used to supply clean air to the combustion chamber, then fuel economy and exhaust cleanliness are improved, but the engine becomes bulky and cold starting becomes difficult
Solution Approach 1:
The invention merges the air intake function and air cleaning function into a single integrated air filter assembly. The air filter is positioned to directly receive ambient air and supply it to the combustion chamber, eliminating the need for separate air shutter and long air duct systems while maintaining the air cleaning capability.
Solution Approach 2:
The invention extracts the air cleaning function from the complex air shutter/duct system and concentrates it in a single air filter component. This extraction simplifies the overall air supply system while preserving the essential function of providing clean air for combustion.
2Object-generated harmful factors
If an extra air shutter and long air duct are used to supply clean air to the combustion chamber, then fuel economy and exhaust cleanliness are improved, but the engine becomes bulky
Solution Approach 1:
The invention merges the air intake function and air cleaning function into a single integrated air filter assembly. The air filter is positioned to directly receive ambient air and supply it to the combustion chamber, eliminating the need for separate air shutter and long air duct systems while maintaining the air cleaning capability.
3Quantity of substance
If an extra air shutter is used to intake outdoor air, then clean air supply is improved, but cold starting becomes difficult due to inability to deliver rich fuel-air mixture
Solution Approach 1:
The invention employs a valve mechanism that dynamically adjusts the air intake path based on engine operating conditions. During cold starting, the valve directs a richer fuel-air mixture from the crankcase to the combustion chamber. During normal operation, the valve switches to supply clean ambient air through the air filter, thus adapting to different operational requirements.
4Quantity of substance
If a long air duct is used to supply air to the cylinder, then air cleaning is improved, but the engine becomes bulky and weight increases
Solution Approach 1:
The invention merges the air intake function and air cleaning function into a single integrated air filter assembly. The air filter is positioned to directly receive ambient air and supply it to the combustion chamber, eliminating the need for separate air shutter and long air duct systems while maintaining the air cleaning capability.
Solution Approach 2:
The invention extracts the air cleaning function from the complex air shutter/duct system and concentrates it in a single air filter component. This extraction simplifies the overall air supply system while preserving the essential function of providing clean air for combustion.
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
The solution enables easier cold starting and reduces engine bulk, improving fuel economy and exhaust cleanliness while maintaining the advantages of stratified charge systems, making the engine more suitable for compact applications.
Implementation Method 1
a separator for cleaning of air coming from the crankcase from lubricating oil and fuel, if any, said separator having a centrifugal chamber, in which the lubricating oil and the fuel, if any, in a circulating motion are thrown outwards to a circumferential wall
Data Source
AI summary
The invention related to a two-stroke internal combustion engine (1), comprising a crankcase (2), which has an air intake (3), and at least one cylinder (4), which is connected to the crankcase (2) and which, together with a piston (5) arranged therein, defines a combustion chamber (6). The cylinder (4) has at least one air inlet (7), which via an air duct (8) communicates with the crankcase (2), in which a mixture of air and lubricating oil and fuel, if any, is contained. The air duct (8) is connected to the crankcase (2) via a separator (10) for cleaning of air coming from the crankcase (2) from lubricating oil and fuel, if any. The separator (10) has a centrifugal chamber (11), in which the lubricating oil and the fuel, if any, in a circulating motion are thrown outwards to a circumferential wall (12) and thus substantially cleaned air is passed, through a chamber outlet (13), which with respect to said circulating motion is a radially inner outlet, to said air duct (8) to be supplied to the combustion chamber (6) through the air inlet (7).