Variable Aperture Separator for Crankcase Oil Aerosol Removal
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Solution Overview
Problem
Current separators in crankcase ventilation systems struggle to achieve high separation efficiency for oil aerosols, particularly for particles smaller than 0.2 μm, and often require additional components like filters or powered systems, which can be costly and prone to clogging or wear, while also facing challenges in maintaining acceptable crankcase pressure levels.
Innovation Solution
A separator system with multiple stages, including a variable impactor separator and a pump, which adjusts the aperture size based on pressure differentials to maintain efficient separation and control crankcase pressure, utilizing a jet pump to enhance separation efficiency without excessive pressure rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single separator is used to separate oil aerosols from blow-by gas, then the device complexity is low, but the separation efficiency is insufficient (70%-80% gravimetric efficiency)
Solution Approach 1:
The separator is divided into multiple stages (first separator, second separator, and optionally third separator) arranged in series. Each stage handles a portion of the separation task, with the first separator removing larger particles and subsequent separators handling finer aerosols. This segmentation achieves over 95% gravimetric separation efficiency while keeping individual separator structures relatively simple.
2Manufacturing precision
If the pressure differential across the separator is increased to improve separation efficiency, then the separation performance improves, but the crankcase pressure rises excessively causing oil leakage
Solution Approach 1:
The total pressure differential (e.g., 100 mbar) is divided into multiple smaller stages. The first separator operates at a lower pressure differential (e.g., 30-50 mbar) removing larger particles, while subsequent separators handle the remaining aerosols at reduced pressure differentials. This segmentation maintains high separation efficiency while keeping crankcase pressure within acceptable limits to prevent oil leakage.
3Manufacturing precision
If additional components like filters or powered systems are added to improve separation efficiency, then the separation performance improves, but the device complexity and cost increase
Solution Approach 1:
The separator system uses the kinetic energy and momentum of the incoming blow-by gas stream itself to achieve separation. The gas stream is directed to impinge on impactor surfaces, and centrifugal force in cyclonic separators utilizes the rotational motion of the gas. This self-service approach achieves over 95% separation efficiency without requiring external power sources, filters, or complex mechanical components.
4Manufacturing precision
If a fixed aperture separator is used, then the device complexity is low, but the separation efficiency varies with changing pressure differentials
Solution Approach 1:
The separator incorporates a variable aperture mechanism where the opening size is adjusted dynamically based on operating conditions. A diaphragm or movable wall responds to pressure differential changes, automatically optimizing the aperture size to maintain consistent separation efficiency across varying engine loads and speeds. This dynamic adjustment ensures optimal performance without requiring complex external control systems.
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 system achieves significantly higher gravimetric and fractional separation efficiencies, exceeding 95% and minimizing the need for additional regulators, while maintaining crankcase pressure within acceptable limits, thus addressing the limitations of existing technologies.
Implementation Method 1
a pump coupled to the second separation stage and arranged to generate an area of reduced pressure to draw the first fluid stream through the first and second separation stages
Implementation Method 2
the first fluid stream is accelerated through the aperture and is incident upon an impaction surface such that contaminants are separated from the first fluid stream
Implementation Method 3
the first fluid stream is accelerated through the aperture and is incident upon an impaction surface such that contaminants are separated from the first fluid stream
Implementation Method 4
a variable impactor separator comprising: a first chamber arranged to receive the first fluid stream; a second chamber coupled to the first chamber through at least one aperture arranged such that the first fluid stream is accelerated through the aperture and is incident upon an impaction surface such that contaminants are separated from the first fluid stream
Data Source
AI summary
A separator has a first inlet arranged to receive a fluid stream, and first and second separation stages coupled together in series; A pump coupled to the second separation stage generates an area of reduced pressure to draw the fluid stream through the first and second separation stages. One of the stages includes a variable impactor separator comprising a first chamber arranged to receive the fluid stream, and a second chamber coupled to the first chamber through an aperture to accelerate the first fluid stream. The stream is incident upon an impaction surface to separate contaminants from the fluid stream. An actuator adjusts the open area of the aperture according to a pressure differential between fluid pressure in the first chamber and a reference fluid pressure in a third chamber. The other of the separation stages is a second variable impactor separator or a filter media.