Bearing Drainage Ejector for Turbine Oil Retention During Pitching
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Solution Overview
Problem
Aircraft turbine engine lubricated enclosures face issues with oil retention during pitch angle changes, leading to potential immersion of sensitive elements, and existing solutions complicate design and increase mass with dedicated oil circuits.
Innovation Solution
Incorporating drainage holes in the rolling bearings and a lubricant ejector system where the highly-pressurized lubricant from these holes supplies the ejector, eliminating the need for a dedicated oil circuit by using the lubricant to drive a secondary flow and prevent oil retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated oil circuit with ejector is implemented to prevent oil retention during pitch angle changes, then oil retention is reduced, but device complexity and mass increase
Solution Approach 1:
The invention merges the ejector function into the existing bearing drainage system. The ejector is integrated with the bearing outer ring and uses the same oil drainage path, combining two functions (bearing drainage and critical area oil removal) into a single integrated system, thereby reducing overall device complexity while maintaining oil retention prevention
Solution Approach 2:
The ejector is designed to be self-activated by the pressurized oil flow that naturally drains from the bearing. The high-pressure oil exiting the bearing automatically triggers the ejector mechanism without requiring external power or control systems, eliminating the need for additional pumps or control circuits and reducing system complexity
2Reliability
If a dedicated oil circuit with ejector is implemented to prevent oil retention during pitch angle changes, then oil retention is reduced, but mass increases
Solution Approach 1:
The ejector is integrated with the bearing outer ring structure, merging two components into one. This eliminates the need for separate mounting structures and reduces overall mass while maintaining the oil retention prevention function
Solution Approach 2:
The ejector utilizes the existing pressurized oil flow from bearing drainage as its activation mechanism, eliminating the need for additional pumps, motors, or power supply systems that would add significant mass to the enclosure
3Productivity
If drainage holes are provided in bearing outer ring, then oil can escape from bearing, but oil may accumulate in critical area during pitch angle changes
Solution Approach 1:
The ejector is positioned and configured to act preemptively on oil that enters the critical area. The geometry of the ejector and its activation threshold are designed to trigger oil removal before the oil can accumulate to harmful levels, preventing reliability issues before they occur
Solution Approach 2:
The ejector acts as an intermediary mechanism between the bearing drainage system and the critical area. It intercepts the draining oil flow and redirects it away from the critical area, mediating between the high-pressure drainage flow and the vulnerable seal regions
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
Simplifies the design, reduces mass, and effectively prevents oil stagnation in critical areas, protecting rotating elements and seals during pitch angle changes by utilizing the pressurized lubricant to drive the ejector's secondary flow, ensuring efficient lubricant recovery and reduced risk of immersion.
Implementation Method 1
the crossing of this primary flow in the ejector drives, by suction, a secondary lubricant flow located around the nozzle of the ejector. The secondary flow is thus sucked into the nozzle before being expelled therefrom, with the primary lubricant flow.
Data Source
AI summary
A lubricated enclosure for an aircraft turbine engine, including a drained roller bearing provided with drainage orifices, as well as a lubricant ejector intended to limit the retention of lubricant in a critical zone of the enclosure, the ejector being intended to be passed through by a primary lubricant flow in order to drive a secondary lubricant flow located around a nozzle of the ejector housed in the critical zone of the enclosure. The enclosure includes a device for establishing communication between the drainage orifices and the ejector, such that the lubricant that escapes from the drainage orifices supplies the ejector in order to form the primary flow.