Prechamber Valve Timing via Pressure Release Channel
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Solution Overview
Problem
In engines with variable intake valve closing (VIC), the prechamber valve closing timing is dependent on the intake valve closing timing, leading to potential over-rich mixtures in the prechamber due to delayed intake valve closure, which complicates accurate control of the prechamber valve in existing hydraulic actuating systems.
Innovation Solution
A prechamber arrangement with a pressure releasing channel that allows pressure to be released from the first chamber before the second piston returns to its initial position, enabling independent timing of the prechamber valve closure and reducing dependence on intake valve closing timing, using a second piston with a pressure releasing channel configured to release pressure when the second piston is in a predetermined position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the prechamber valve is controlled by the same hydraulic actuating arrangement as the intake valve, then the device complexity is reduced, but the prechamber valve closing timing becomes dependent on the intake valve closing timing, leading to inaccurate control
Solution Approach 1:
The hydraulic actuating system is segmented into two independent control paths: one for the intake valve and another for the prechamber valve. The prechamber valve has its own dedicated piston (first piston) and hydraulic chamber (first chamber), separated from the intake valve's hydraulic system. This segmentation allows independent timing control while maintaining hydraulic actuation, resolving the contradiction between simplified complexity and precise timing control.
Solution Approach 2:
A second piston acts as an intermediary between the cam mechanism and the prechamber valve's first piston. The second piston translates the cam's mechanical motion into hydraulic pressure that controls the first piston, providing a buffered control mechanism that decouples the prechamber valve timing from direct intake valve timing dependence while maintaining system simplicity.
2Productivity
If the intake valve closing is delayed using hydraulic fluid retention, then the combustion efficiency is improved, but the prechamber valve closing is also delayed, causing the mixture to become too rich
Solution Approach 1:
The hydraulic control system is segmented into independent first and second chambers with separate pressure control mechanisms. The second chamber can retain hydraulic fluid to delay intake valve closing for improved combustion efficiency, while the first chamber's pressure is independently controlled via the pressure releasing channel to ensure timely prechamber valve closing, preventing excessive fuel enrichment.
Solution Approach 2:
The pressure releasing channel is configured to proactively release pressure from the first chamber at a predetermined position of the second piston, before the delayed intake valve closing would otherwise cause the prechamber valve to close too late. This preliminary pressure release action ensures the prechamber valve closes at the correct timing regardless of intake valve delays, maintaining proper mixture richness.
3Manufacturing precision
If a separate actuating mechanism is provided for the prechamber valve, then the timing control precision is improved, but the device complexity increases
Solution Approach 1:
The second piston serves multiple functions: it acts as a cam follower to convert mechanical motion to hydraulic pressure, controls the hydraulic pressure in the first chamber, and indirectly influences both intake and prechamber valve timing. This multi-functionality provides precise prechamber valve control without requiring a completely separate actuating mechanism, balancing complexity and precision.
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 arrangement allows for precise control of the prechamber valve opening and closing, independent of intake valve timing, preventing over-rich mixtures and improving combustion efficiency in engines with VIC systems.
Implementation Method 1
the first piston being in mechanical connection with the prechamber valve for moving the prechamber valve in the opening direction of the valve when hydraulic pressure is applied on the piston surface of the first piston
Implementation Method 2
a second piston, which is movable and comprises a piston surface for pressurizing pressure medium and for applying the hydraulic pressure of the pressure medium on the piston surface of the first piston
Implementation Method 3
The prechamber arrangement is provided with a pressure releasing channel, which is configured to release pressure from the first chamber for allowing closing of the prechamber valve
Data Source
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AI summary
The prechamber arrangement for a piston engine (1) comprises a prechamber (17), a prechamber valve (19), a first piston (23) arranged in a first chamber (27) and comprising a piston surface (31) delimiting the first chamber (27), the first piston (23) being connected to the prechamber valve (19) for moving the valve (19) in the opening direction of the valve (19) when hydraulic pressure is applied on the piston surface (31) of the first piston (23), and a second piston (29), comprising a piston surface (32) for pressurizing pressure medium and for applying the hydraulic pressure of the pressure medium on the piston surface (31) of the first piston (23). The prechamber arrangement is provided with a pressure releasing channel (34), which is configured to release pressure from the first chamber (27) when the second piston (29) is in a certain predetermined position for allowing closing of the prechamber valve (19).