Epicyclic Gear Journal Bearings for Uniform Lubricant Flow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas turbine engines with geared architectures face challenges in efficiently delivering lubricants to reduce friction and wear across components, especially when operating at varying rotational speeds and conditions, leading to inadequate lubrication at higher positions within the epicyclic gear system.
Innovation Solution
An epicyclic gear system with varying cross-sectional areas of lubricant passageways in journal bearings, positioned vertically to ensure consistent lubricant flow to star gear assemblies, including axially and radially extending passageways connected to a lubricant manifold, ensures adequate lubrication across all operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform cross-sectional area lubricant passageways are used in all journal bearings, then the device complexity is reduced, but the lubrication effectiveness at higher vertical positions deteriorates due to gravity-induced flow maldistribution
Solution Approach 1:
The patent applies local quality by varying the cross-sectional area of lubricant passageways according to the vertical position of each journal bearing. Upper journal bearings are equipped with larger cross-sectional area passageways to compensate for gravity-induced flow reduction, while lower bearings have smaller passageways. This localized adaptation ensures uniform lubricant delivery to all star gear assemblies regardless of their vertical position, resolving the contradiction between lubrication effectiveness and device complexity.
2Reliability
If larger cross-sectional area passageways are used in upper journal bearings to compensate for gravity, then lubrication effectiveness is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by systematically varying the cross-sectional area parameter of lubricant passageways based on vertical position. This controlled parameter variation compensates for gravitational effects on lubricant flow, ensuring that each journal bearing receives adequate lubricant flow to maintain consistent film thickness. The systematic approach to parameter change allows for manageable manufacturing tolerances while achieving the desired lubrication consistency across all bearings.
3Adaptability or versatility
If the gear system operates at varying rotational speeds from windmill to flight idle, then the adaptability is improved, but the lubrication consistency deteriorates due to changing centrifugal forces
Solution Approach 1:
The patent applies equipotentiality by designing the passageway cross-sectional areas to compensate for gravitational potential differences at various vertical positions. This creates an equipotential lubrication system where the combined effect of gravity and pressure gradient results in uniform lubricant delivery to all journal bearings. The design ensures that lubrication consistency is maintained across the full operational speed range from windmill to flight idle, as the gravitational compensation works effectively at all rotation speeds.
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 maintains a consistent lubricant film thickness and flow rate, preventing wear and ensuring efficient operation across a wide range of rotational speeds and positions within the gear system, even when lubricant supply pressure is reduced.
Implementation Method 1
The journal bearing includes one or more lubricant passageways to deliver a flow of lubricant to a selected location of the star gear assembly
Implementation Method 2
Fluids, such as oil are utilized to the geared architecture, in particular to reduce friction and wear between the components of the geared architecture
Data Source
AI summary
An epicyclic gear system includes a sun gear, a ring gear, and two or more star gear assemblies enmeshed between the sun gear and the ring gear. Each star gear assembly includes a star gear and a journal bearing supportive of the star gear. The journal bearing includes one or more lubricant passageways 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.