Two-Stroke Engine Fuel Valve Control by Revolution Blocks
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Solution Overview
Problem
Two-stroke engines require complex and high-energy electromagnetic fuel valves due to very short switching times, especially at high speeds, leading to undesirable operator feedback during mode transitions and challenging fuel metering.
Innovation Solution
Control the fuel valve based on consecutive blocks of crankshaft revolutions, opening and closing it exactly once within each block, allowing the use of a simpler valve design and synchronized control with blocks rather than individual engine cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the fuel valve is opened and closed once within each engine cycle to meter fuel, then fuel metering is achieved, but the switching time becomes very short at high speeds requiring a complex high-energy electromagnetic valve
Solution Approach 1:
The patent segments the control cycle by grouping multiple crankshaft revolutions into blocks (e.g., 2-20 revolutions per block). The fuel valve is actuated once per block rather than once per revolution, dividing the continuous control into discrete manageable units. This segmentation allows sufficient actuation time within each block while maintaining precise cumulative fuel metering across the block period.
Solution Approach 2:
The patent implements periodic action by actuating the fuel valve at regular intervals corresponding to completed blocks of crankshaft revolutions. Instead of continuous or per-revolution actuation, the valve opens and closes periodically once per block, creating a rhythmic control pattern that provides adequate switching time while achieving the required fuel delivery precision through the periodic accumulation of fuel blocks.
2Measurement precision
If the fuel valve switching frequency is increased to match engine cycles at high speeds, then fuel metering accuracy is maintained, but the switching time becomes insufficient for simple valve designs
Solution Approach 1:
The patent segments the fuel delivery requirement into blocks of multiple crankshaft revolutions, allowing the valve to remain closed for several revolutions and then open for a sustained period to deliver the cumulative fuel quantity for the block. This segmentation extends the effective switching time by distributing fuel delivery across a longer temporal window while maintaining precise control through block-based metering.
Solution Approach 2:
The control system performs preliminary calculation of the required fuel quantity for an entire block of crankshaft revolutions before actuating the valve. The valve is then opened in advance for the duration needed to deliver the pre-calculated fuel amount, ensuring that the switching time is sufficient for simple valve designs while the preliminary computation maintains fuel quantity accuracy.
3Speed
If the electromagnetic valve is designed for high energy requirements to achieve fast switching, then switching speed is sufficient, but the valve becomes complex and energy-consuming
Solution Approach 1:
The patent employs periodic action by actuating the electromagnetic valve once per block of crankshaft revolutions rather than continuously or per revolution. This periodic operation allows the valve to remain in a stable state (open or closed) for extended periods, requiring minimal energy for maintaining state compared to frequent switching. The electromagnetic coil only consumes significant energy during the brief actuation moments, dramatically reducing overall energy consumption while maintaining adequate switching speed when actuation occurs.
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
Enables the use of a simpler electromagnetic fuel valve by providing sufficient actuation time at high speeds, reducing switching time issues and improving fuel metering precision while maintaining stable engine operation.
Implementation Method 1
The fuel valve (18) is an electromagnetic valve which meters fuel supply to an intake port (14)
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A two-stroke engine (1) has a cylinder (2) and a crankcase (4). A combustion chamber (3) is formed in the cylinder (2), which is bounded by a piston (5) mounted to reciprocate within the cylinder (2). The piston (5) drives a crankshaft (7) rotatably mounted in the crankcase (4). An electromagnetic fuel valve (18) is provided, which controls the amount of fuel supplied to an intake port (14) via at least one outlet (19). A control device (31) is provided for actuating the fuel valve (18). A quasi-steady state of the two-stroke engine (1) is a state in which the throttle element (16) is adjusted by less than 10% of its maximum adjustment over a crankshaft angle (α) of 360°.A method for operating the two-stroke engine (1) provides that, after the starting process, the control of a fuel valve (18) takes place in at least a quasi-stationary state such that the fuel valve (18) is opened and closed exactly once within each block (68, 69, 70, 71, 72, 73) of consecutive revolutions (62, 63, 64, 65, 66, 67) of the crankshaft (7). Each block (68 to 73) comprises from 2 to 20 revolutions (62 to 67) of the crankshaft (7).