Two-Stroke Piston Pump Engine Air Flow Path
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Solution Overview
Problem
Conventional two-stroke engines face limitations in power output due to inefficient air flow and lubrication, with oil added to the air-fuel mixture causing higher emissions and crankcase lubrication being difficult to implement, leading to reduced performance and increased emissions.
Innovation Solution
A two-stroke combustion engine design featuring a separate piston pump mechanically connected to the combustion piston, with a direct and efficient air flow path to the combustion cylinder, utilizing a one directional valve and Skotch yoke mechanism to minimize flow resistance and heat exposure, allowing for higher air density and power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oil is added to the air/air-fuel mixture to lubricate engine parts, then lubrication is achieved, but emissions increase
Solution Approach 1:
The patent divides the lubrication function from the air/fuel system by introducing a separate crankcase lubrication system. The crankcase contains oil that is pumped to lubricate bearings and moving parts independently, while the air/fuel mixture remains separate and oil-free, thus achieving lubrication without increasing emissions from the exhaust.
Solution Approach 2:
The patent extracts the lubrication function from the air/fuel charge by implementing a dedicated crankcase lubrication system. The oil is taken out from the combustion process and placed in a separate crankcase reservoir, where it is delivered to lubrication points via a pump, eliminating the need to contaminate the air/fuel mixture with oil.
2Device complexity
If the air inlet is positioned far from the combustion cylinder with long flow paths and sharp bends, then the engine structure is simplified, but flow resistance increases and power output decreases
Solution Approach 1:
The patent positions the air inlet close to the combustion cylinder and pre-arranges the air flow path to minimize bends and restrictions before the air enters the combustion chamber. This preliminary optimization of the flow path ensures that air arrives at the combustion cylinder with minimal resistance and maximum velocity, enhancing power output without complicating the overall engine structure.
3Volume of stationary object
If the air stays in the crankcase for multiple cycles before entering the combustion cylinder, then the crankcase volume is充分利用, but the air temperature increases and density decreases
Solution Approach 1:
The patent implements a direct air flow path that allows air to rush through the crankcase and enter the combustion cylinder in a single cycle rather than lingering for multiple cycles. This rapid transit minimizes the time air is exposed to heat from the crankcase walls and exhaust gases, maintaining higher air density and improving combustion efficiency.
4Ease of manufacture
If a piston pump is mounted far from the combustion cylinder with the outlet not directed towards the combustion cylinder, then the piston pump can be driven by a con rod mounted to the combustion engine crankshaft, but the air flow efficiency is reduced
Solution Approach 1:
The patent merges the piston pump mounting location with the combustion cylinder by positioning the piston pump outlet to directly face the combustion cylinder inlet. This integration allows the air pump to efficiently deliver compressed air directly into the combustion chamber, maximizing air flow efficiency while maintaining a compact engine layout that is feasible to manufacture.
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 design enhances power output by maintaining higher air density and reducing heat exposure, achieving up to 40-45% improvement in power output at higher RPMs and enabling better lubrication without adding oil to the air-fuel mixture, thus reducing emissions.
Implementation Method 1
a separate piston pump (3a, 21, 24) having a piston pump cylinder (3b) with a piston pump center axis (20b) and a pump piston (25) movable within the piston pump cylinder (3b)
Implementation Method 2
The air inlet (10) comprises a one directional valve (9) substantially allowing air to flow in an air inlet direction and hindering air from flowing in a direction opposite to the air inlet direction
Implementation Method 3
utilizing a one directional valve and Skotch yoke mechanism to minimize flow resistance
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
A two stroke combustion engine comprising at least one combustion cylinder (13) having a cylinder center axis (19), a combustion piston (12) movable within the combustion cylinder (13), the combustion piston (12) having a first compression direction (CD) along the cylinder center axis (19). The two stroke combustion engine further comprising at least one separate piston pump (3a) having a piston pump cylinder (3b) with a piston pump center axis (20b) and a pump piston (25) movable within the piston pump cylinder (3b). The separate piston pump (3a) is in movable mechanical connection (18) with the combustion piston (12). The two stroke combustion engine further comprising an air inlet (10) having an air inlet center axis (20a). The separate piston pump (3a), the air inlet (10) and the combustion cylinder (13) are in fluid connection with each other by a transfer channel (11), and the piston pump center axis (20b) intersects a cylinder plane (X-19) extending from the cylinder center axis (19), and the intersection defines a ray (19') extending from the intersection in the first compression direction (CD). A normal axis (N) extends perpendicularly from the cylinder plane (X-19), the normal axis (N) intersects the piston pump center axis (20b). An angle, measured from the intersection between the ray (19') and a point on the piston pump center axis (20b), located in the piston pump cylinder (3b), is between 30° and 160°.