Disk Demister Passages for Low-Backpressure Gearbox Venting
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Solution Overview
Problem
Existing air-oil separating devices for gearing systems, such as those in auxiliary power units, face challenges in efficiently removing oil mist particles from air while generating increased backpressure and contributing to oil consumption rates.
Innovation Solution
A demister device with a disk-shaped body and radial fluid passages that utilizes centrifugal forces by rotating about a central axis, creating swirling motions to separate oil mist particles from air, with angled passages and entrance channels to enhance separation efficiency and reduce backpressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire mesh or sintered barrier filter media are used to separate oil mist from air, then oil separation effectiveness is improved, but backpressure increases
Solution Approach 1:
The patent replaces the traditional mechanical barrier filter media (wire mesh or sintered materials) with a centrifugal separation system. The demister assembly utilizes rotational centrifugal force generated by the spinning air stream to separate oil mist particles from air, eliminating the need for physical filter barriers that cause backpressure while maintaining effective oil separation.
Solution Approach 2:
The invention employs pneumatic principles by using the kinetic energy and rotational motion of the air stream itself to achieve separation. The spinning air creates centrifugal forces that naturally separate the denser oil mist particles from the air flow, using the fluid dynamics of the air-oil mixture rather than mechanical filtration.
2Reliability
If traditional air-oil separating devices are used, then oil mist particles are removed from air, but oil consumption rate increases
Solution Approach 1:
By replacing barrier filtration with centrifugal separation, the system achieves oil mist removal without the oil consumption associated with traditional filters. The centrifugal force separates and returns oil to the gearbox, preventing oil loss that would occur with barrier media that trap and consume oil particles.
Solution Approach 2:
The centrifugal separation system recovers oil from the air stream and returns it to the gearbox, rather than discarding it through barrier filters. This recovery mechanism maintains oil levels and reduces consumption by continuously separating and returning usable oil to the lubrication system.
3Reliability
If barrier filter media are used for oil separation, then oil entrainment is improved, but device complexity increases
Solution Approach 1:
The patent simplifies the device structure by replacing complex barrier filter media assemblies with a simple demister assembly that utilizes the existing rotational motion of the air stream. This mechanical substitution reduces structural complexity while maintaining or improving oil entrainment efficiency through centrifugal separation.
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
Effectively and efficiently removes oil mist particles from air, reducing oil consumption and backpressure by leveraging centrifugal forces and swirling motions within the demister, ensuring oil remains in the gearbox and filtered air is discharged.
Implementation Method 1
The demister includes a main body shaped as a disk having an inner annular rim coupled to an outer annular rim through a first wall and a second wall opposite from the first wall. A central opening is defined by the inner annular rim and extends between and through the first wall and the second wall. The main body is configured to be rotated about a central longitudinal axis to create centrifugal forces that separate oil mist particles from air.
Implementation Method 2
The fluid passage(s) is angled with respect to a radial line extending from the central longitudinal axis. The fluid passage(s) may be angled toward or away from a direction of rotation. For example, the fluid inlet opening may be canted radially forward or rearward with respect to a direction of rotation from the fluid outlet opening.
Data Source
AI summary
A demister for a gearing system includes a main body shaped as a disk having an inner annular rim coupled to an outer annular rim through a first wall and a second wall opposite from the first wall. A central opening is defined by the inner annular rim and extends between and through the first wall and the second wall. The main body is configured to be rotated about a central longitudinal axis to create centrifugal forces that separate oil mist particles from air. At least one fluid passage extends radially between and through the inner annular rim and the outer annular rim. The fluid passage(s) includes a fluid inlet opening in the outer annular rim and a fluid outlet opening in the inner annular rim. The fluid inlet opening is configured to accept incoming air. The fluid outlet opening is configured to discharge filtered air.