Step-Wise Hydraulic Pumping System for Two-Stroke Engine Lubrication
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Solution Overview
Problem
Current lubrication systems for large slow-running two-stroke marine diesel engines face challenges in precise volume control and timing due to uncertainties introduced by long lubricant conduits, which lead to imprecise injection timing and volume, especially under high pressure and short injection periods.
Innovation Solution
A hydraulic-driven multi-step piston-based pumping system is implemented for each injector, allowing precise determination of injected volumes by predetermined stroke-lengths and pressures, minimizing uncertainties through sequential step-wise lubricant ejection and retraction, and utilizing a non-return outlet-valve system for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If long lubricant conduits are used to supply lubricant to injectors, then the lubrication system can cover larger engine configurations, but imprecise injection timing and volume control occur due to conduit expansion and contraction under high pressure
Solution Approach 1:
The patent extracts the pumping function from a remote central unit and places it directly at each injector location. Each injector contains its own hydraulic-driven piston-based pumping system, eliminating the need for long lubricant conduits that cause timing and volume precision errors. The pumping system is integrated into the injector housing, with the plunger-member positioned directly adjacent to the lubricant supply, thereby removing the source of expansion and contraction errors.
Solution Approach 2:
The patent introduces a hydraulic fluid as an intermediary medium to transmit power from the controller to the piston-based pumping system. The controller supplies hydraulic fluid through conduits to actuate the plunger-member, separating the control function from the lubricant supply function. This allows precise electronic control of injection timing and volume without the lubricant conduits themselves causing timing errors.
2Reliability
If high pressure is used for lubricant injection, then atomization and lubrication effectiveness improve, but conduit expansion and contraction increase, reducing injection precision
Solution Approach 1:
The patent extracts the high-pressure generation function from the remote lubricant supply system and places it locally at each injector. The piston-based pumping system generates high pressure (35-40 bars or higher) directly at the injection point, eliminating the need for long high-pressure conduits that expand and contract. The high pressure is generated only when needed for injection, not continuously throughout the lubricant supply lines.
Solution Approach 2:
The patent makes the injection system dynamic by using a piston-based pumping system that generates high pressure only during the injection phase. The plunger-member moves reciprocally to create high pressure pulses synchronized with the injection timing, rather than maintaining continuous high pressure in conduits. This dynamic pressure generation eliminates conduit expansion and contraction errors.
3Loss of substance
If short injection periods are used, then oil consumption is reduced, but timing precision becomes more critical and harder to achieve with long conduits
Solution Approach 1:
The patent extracts the timing control function from the lubricant supply system and places it directly at the injector. The controller precisely controls the timing of hydraulic fluid supply to the plunger-member, enabling accurate injection timing without the delays and uncertainties introduced by long lubricant conduits. The injection timing is controlled locally at each injector independently.
Solution Approach 2:
The controller prepares for precise injection timing by pre-positioning the plunger-member and pre-supplying hydraulic fluid to the injector before the injection event. The system is ready to inject immediately when triggered, eliminating delays associated with lubricant travel through long conduits. The short injection period is achieved through rapid local actuation rather than delayed response from remote control.
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 ensures precise and reliable lubricant injection with improved timing and volume control, reducing errors and enhancing the longevity of diesel engines by minimizing the effects of conduit expansion and contraction, thus optimizing lubrication efficiency.
Implementation Method 1
a reciprocal plunger-member (29) in contact with the front chamber (16D), which, in the injection phase, is driven by the actuator-member the stroke-length towards the nozzle aperture (5'), which is causing pressure rise in the front chamber (16D) and causes pumping a first predetermined lubricant volume
Implementation Method 2
causes pumping a first predetermined lubricant volume, defined by the stroke-length, through the non-return outlet-valve (17) and the nozzle aperture (5') into the cylinder (1)
Data Source
Figure 1
Figure 2a~2c
Figure 3a~3c
AI summary
A large slow-running two-stroke engine comprising a cylinder (1) with a reciprocal piston inside and with a plurality of injectors (4) distributed along a perimeter of the cylinder (1) for injection of lubricant into the cylinder (1) at various positions on the perimeter. A controller (11) is provided for controlling the amount and timing of the lubricant injection through the injectors (4). The injectors (4) comprise a hydraulic pumping system (27, 28, 29) with a hydraulically driven plunger-member (29) that pressurises the lubricant inside the injectors (4) up to ejection through the nozzle aperture (5'). The plunger is activated in steps or comprises multiple plunger elements that are activated sequentially.