Segmented Bearing Arrangement for Gearbox Vibration Damping
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Solution Overview
Problem
Existing rolling element bearings in gas turbine engines fail to provide sufficient structural resistance to vibration, leading to issues like tooth misalignment, excessive wear, and cabin noise due to inadequate damping mechanisms, particularly in power transmission gearboxes.
Innovation Solution
A bearing arrangement featuring radially extending rigid supports and damping sectors with elongate flexible members that absorb and dissipate vibrational energy, including damping members with varying lengths and orientations to target specific or broad frequency ranges, and a combination of core and damping coatings for enhanced energy dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If squeeze film dampers with oil flow are used to damp vibration, then vibration damping is improved, but structural resistance and reliability deteriorate
Solution Approach 1:
The bearing arrangement is segmented into rigid supports and damping sectors, where rigid supports provide structural resistance and damping sectors provide vibration damping. This segmentation allows each component to specialize in its function without compromising the other.
Solution Approach 2:
The bearing arrangement uses a composite structure combining rigid materials (for structural support) and flexible damping materials (for vibration absorption). This composite approach enables simultaneous achievement of high structural resistance and effective vibration damping.
2Object-affected harmful factors
If damping sectors with flexible members are added to the bearing arrangement, then vibration damping is improved, but device complexity increases
Solution Approach 1:
The bearing is divided into discrete damping sectors with flexible members, allowing the damping function to be added in a modular fashion rather than requiring a complete redesign of the bearing structure.
Solution Approach 2:
Damping sectors are placed at specific locations around the bearing circumference where vibration damping is most needed, rather than uniformly distributing damping elements throughout the entire bearing structure.
3Object-affected harmful factors
If the number of rigid supports and damping sectors is made different from the number of rollers, then vibration harmonic reduction is improved, but manufacturing precision requirements increase
Solution Approach 1:
The bearing arrangement uses an asymmetric configuration where the number of rigid supports and damping sectors deliberately differs from the number of rollers. This asymmetry breaks the harmonic resonance patterns that would otherwise occur at roller passage frequencies.
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 reduces vibration levels across various frequencies, maintaining shaft alignment and reducing wear, while eliminating the need for oil feed pipes, thus simplifying the arrangement and enhancing passenger comfort by significantly decreasing engine vibration.
Implementation Method 1
each damping member comprising an elongate flexible member held rigidly at one or both ends thereof, such that vibrational movement of the inner or outer support annulus causes bending of the elongate flexible members. Advantageously, the bending of the elongate flexible members absorbs and dissipates the vibrational energy
Implementation Method 2
Each damping member may comprise an elongate shim comprising a core having a first spring constant, and a damping coating applied on one or both sides of the core comprising a second spring constant different to the first spring constant. Advantageously, shear interaction between the core and the coating may dissipate energy where the damping member is caused to flex.
Data Source
AI summary
A bearing arrangement (30) comprises an inner support annulus (33), an outer support annulus (31), and a plurality of rollers (34) therebetween. At least one of the inner and the outer support annulus (33, 31) comprises one or more radially extending rigid supports (37) and one or more damping sectors (38a, 38b, 38c). The one or more rigid supports (37) are circumferentially interposed between one or more damping sectors (38a, 38b, 38c). Each damping sector (38a, 38b, 38c) comprises at least one damping member (39) comprising an elongate flexible member held rigidly at one or both ends thereof, such that vibrational movement of the inner or outer support annulus (33, 31) causes bending of the elongate flexible members (39).