2-Stroke Engine Piston Edge Controls Overflow Channel Flow
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Solution Overview
Problem
Existing internal combustion engines, particularly 2-stroke engines, face challenges in achieving low exhaust gas values and optimizing fuel consumption, as unburned ignition mixture can escape into the exhaust system through overflow channels.
Innovation Solution
The design incorporates a piston with a lower edge that interacts with a counter-body in the crankcase to control the inlet cross-section of the overflow channel, allowing precise metering of the ignition mixture into the combustion chamber, reducing fuel consumption and improving exhaust gas quality by ensuring a discrete quantity of mixture reaches the combustion chamber without direct fluidic connection between the crankcase and combustion chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the overflow channel is open from the crankcase to the combustion chamber, then the ignition mixture can be supplied to the combustion chamber, but unburned ignition mixture escapes into the exhaust system
Solution Approach 1:
The overflow channel is designed with dynamic opening and closing sections. The inlet cross-section is controlled by the piston's lower edge interacting with a counter-body projection, and the outlet cross-section is controlled by the piston's upper edge. This dynamic configuration allows the channel to open for mixture supply and close to prevent unburned mixture escape, resolving the contradiction between productivity and harmful emissions
Solution Approach 2:
The overflow channel operates in periodic cycles synchronized with the piston strokes. During the downward stroke, the inlet cross-section is opened to supply ignition mixture. During the upward stroke, both inlet and outlet cross-sections are closed to prevent unburned mixture from reaching the exhaust. This periodic opening and closing action resolves the contradiction by allowing mixture supply when needed and preventing harmful emissions when not needed
2Productivity
If the inlet cross-section of the overflow channel is enlarged, then more ignition mixture enters the combustion chamber, but fuel consumption increases
Solution Approach 1:
The inlet cross-section of the overflow channel is made dynamic through the interaction between the piston's lower edge and the counter-body projection. This allows the cross-section to be enlarged during the downward stroke to allow rapid filling of the combustion chamber, and then closed during the upward stroke to prevent excessive fuel consumption. The dynamic control resolves the contradiction by allowing high productivity when needed while preventing energy loss during the compression phase
Solution Approach 2:
The inlet cross-section operates periodically - opened during the downward stroke to supply ignition mixture and closed during the upward stroke. This periodic action ensures that a discrete quantity of mixture enters the combustion chamber efficiently during the power stroke while preventing additional fuel consumption during the compression stroke, thereby resolving the contradiction between productivity and energy loss
3Measurement precision
If the piston controls both inlet and outlet cross-sections, then metering precision improves, but device complexity increases
Solution Approach 1:
The piston is designed to perform multiple functions: it controls both the inlet cross-section (via its lower edge interacting with the counter-body projection) and the outlet cross-section (via its upper edge). This multi-functionality improves metering precision without adding separate control mechanisms, thereby resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The control functions for both inlet and outlet cross-sections are merged into a single piston component. The piston's stroke movement simultaneously controls the opening and closing of both cross-sections, eliminating the need for separate control mechanisms and achieving precise metering without increasing device complexity
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 solution enhances exhaust gas quality and reduces fuel consumption by controlling the inlet cross-section of the overflow channel, ensuring ordered flow conditions and separating exhaust gases from the ignition mixture, resulting in improved engine performance and emissions.
Implementation Method 1
the piston has a lower edge that interacts with at least one counter-body in such a way that the stroke movement of the piston with the lower edge of the piston can control an inlet cross section of the transfer channel for the entry of the ignition mixture from the crankcase into the transfer channel
Implementation Method 2
An upper edge of the piston, which opens and closes an outlet cross section of the overflow channels in the manner of a slide valve, serves to open and close the overflow channels
Implementation Method 3
Only with the upward movement of the piston does the outlet cross section close again, and the ignition mixture is subsequently compressed by the upward movement in the direction of top dead center
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The internal combustion engine (100) has a crankcase (10) provided with a cylinder (11) in which a piston (12) is guided in a lifting movement such that a combustion chamber (13) is limited. The ignition mixture is guided from crankcase to combustion space through an overflow channel (14). A movable control element is provided at piston bottom (15) of piston such that inlet cross section (16) of overflow channel for entry of ignition mixture from crankcase is controllable by lifting movement of piston.