Epicyclic Gear Lubrication Layout for Uneven Bearing Positions
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Solution Overview
Problem
Gas turbine engines with geared architectures face challenges in efficiently delivering lubricant to reduce friction and wear across components, particularly at varying rotational speeds and when the engine is not operating, leading to inadequate lubrication at certain positions within the epicyclic gear system.
Innovation Solution
The epicyclic gear system incorporates axially and radially extending lubricant passageways with varying cross-sectional areas based on the vertical position of journal bearings, ensuring consistent lubricant flow through a lubricant manifold and distribution recesses, and includes multiple star gear assemblies enmeshed between a sun gear and a ring gear to maintain a lubricant film for reduced friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single cross-sectional area is used for all lubricant passageways, then the device complexity is reduced, but the lubrication effectiveness varies at different vertical positions
Solution Approach 1:
The patent applies local quality by varying the cross-sectional area of lubricant passageways at different vertical positions within the epicyclic gear system. Journal bearings at lower vertical positions have larger cross-sectional areas to compensate for lubricant accumulation, while upper positions have smaller areas. This localized adaptation ensures consistent lubrication effectiveness throughout the system despite gravitational effects on lubricant distribution.
2Adaptability or versatility
If the engine operates at varying rotational speeds including windmill conditions, then the adaptability is improved, but the lubrication consistency deteriorates
Solution Approach 1:
The patent implements parameter changes by systematically varying the cross-sectional area parameter of lubricant passageways based on vertical position. This geometric parameter modification compensates for the effects of varying rotational speeds and gravitational forces, maintaining consistent lubrication film formation across the full operational range from windmill conditions to high-speed flight idle operation.
3Reliability
If lubricant flow is increased to ensure adequate lubrication at all positions, then the lubrication reliability is improved, but the energy consumption increases
Solution Approach 1:
The patent applies local quality by providing different cross-sectional areas at different vertical positions rather than uniformly increasing flow throughout the system. Lower journal bearings receive higher lubricant flow through larger passageway areas, while upper bearings receive appropriate flow through smaller areas. This localized approach ensures adequate lubrication where needed without unnecessarily increasing overall energy consumption.
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 configuration ensures effective lubrication across the entire epicyclic gear system, preventing wear and maintaining efficiency across a wide range of rotational speeds and operational conditions, including when the engine is not running.
Implementation Method 1
Fluids, such as oil are utilized to the geared architecture, in particular to reduce friction and wear between the components
Implementation Method 2
The epicyclic gear system incorporates axially and radially extending lubricant passageways with varying cross-sectional areas based on the vertical position of journal bearings, ensuring consistent lubricant flow
Implementation Method 3
maintain a lubricant film for reduced friction
Data Source
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AI summary
An epicyclic gear system (36) includes a sun gear (42), a ring gear (40), and two or more star gear assemblies enmeshed between the sun gear and the ring gear. Each star gear assembly includes a star gear (38) and a journal bearing (44) supportive of the star gear. The journal bearing includes one or more lubricant passageways (54, 56) to deliver a flow of lubricant to a selected location of the star gear assembly, wherein a first cross-sectional area of a lubricant passage of a first journal bearing of the two or more star gear assemblies is greater than a second cross-sectional area of the corresponding lubricant passage of a second journal bearing of the two or more star gear assemblies.