Turbomachine Shaft Centering With Directional Bearing Cage Stiffness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current flexible cage technologies for aircraft turbomachine bearings have identical stiffness in all transverse directions, which does not allow for adaptation to different stress directions, leading to potential instability issues at high speeds.
Innovation Solution
A device with a flexible cage system where columns have different clearances in various radial directions, allowing for distinct stiffness in multiple transverse directions, achieved by varying the orientation and size of openings and column bodies, enabling differential movement amplitudes and stress responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If columns with axisymmetric shape are used, then the cage structure is simple and manufacturing is easy, but the stiffness is identical in all transverse directions which causes instability at high speeds
Solution Approach 1:
The patent applies asymmetry by giving the columns different cross-sectional shapes (e.g., rectangular, elliptical, or triangular sections) instead of axisymmetric circular sections. This asymmetric geometry creates different moments of inertia about different axes, resulting in different stiffness values in different transverse directions. The asymmetric column design directly addresses the instability problem by enabling directional stiffness control while maintaining manufacturing feasibility through standard machining processes.
Solution Approach 2:
The patent implements local quality by varying the cross-sectional dimensions and shapes of individual columns based on their specific positional requirements. Each column can have tailored dimensions (width, height, thickness) and cross-sectional geometry to provide optimal stiffness characteristics for its location. This localized optimization allows different regions of the cage to have different stiffness properties, improving overall stability without requiring complete redesign of all components.
2Reliability
If columns with different stiffness in different directions are implemented, then stability is improved, but the device complexity increases
Solution Approach 1:
The asymmetric column design achieves different stiffness in different directions through geometric asymmetry rather than through complex mechanical mechanisms. By simply varying the cross-sectional dimensions and orientation of each column, the patent obtains directional stiffness control without adding extra components, joints, or adjustment mechanisms. This approach improves stability while keeping the overall device structure relatively simple.
Solution Approach 2:
The patent utilizes parameter changes by modifying the geometric parameters of the columns (cross-sectional area, moment of inertia, orientation angles) to achieve the desired stiffness characteristics. Instead of adding complex mechanisms, the solution involves adjusting dimensional parameters such as column width, height, thickness, and rotational orientation. These parameter variations enable directional stiffness control while maintaining a simple overall structure that is easy to manufacture and assemble.
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 provides enhanced stability by postponing the onset of instabilities and allowing for multiple configuration options while reducing costs and development time, as it allows for different stiffness in two perpendicular directions, thereby improving the dynamic performance and reducing the risk of engine instability.
Implementation Method 1
The flexibility of this cage is generally ensured by a capacity for elastic deformation of this cage, for example in torsion and/or in bending.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a device for centring and guiding a shaft of an aircraft turbine engine, said device comprising: - an outer ring (12) of a rolling bearing (14), said ring extending about a main axis (X) and having orifices (42a, 42b) arranged around said axis and oriented parallel to said axis; - an annular bearing support (16) extending about the main axis (X) and at least partially about the ring (12), said support having orifices (44a, 44b) and openings (46a, 46b) arranged about said axis and oriented parallel to said axis; and - a series of studs (40, 41) for linking the ring to the support, said studs being distributed about the main axis (X) and having elongation axes (Y) substantially parallel to the main axis (X), each of said studs comprising a body (40c, 41c) having a first longitudinal end (40a, 41a) engaged in one of the orifices (42a, 42b) of the ring and a second longitudinal end (40b, 41b) engaged in one of the orifices (44a, 44b) of the support, the body of each of said studs passing through one of the openings (46a, 46b) of the support. Some of said studs (40, 41), referred to as first studs (41), have bodies (41c) that pass with a first positive clearance (411) and a second virtually zero clearance (412) through the first openings (46b), said first clearance (411) is oriented in at least a first direction (DI) that is radial relative to said elongation axis (Y), and said second clearance (412) is oriented in at least a second direction (D2) that is radial relative to said elongation axis (Y) and differs from the first direction, said first and second clearances (411, 412) being configured so that the device has different displacement amplitudes in at least two directions perpendicular to said main axis.