Ball Bearing Raceway Drain Layout for Oil Film Damper Compatibility
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Solution Overview
Problem
Existing ball bearing designs with central outer ring drain orifices are incompatible with certain oil film damper designs, increase complexity and cost, and are prone to damage under extreme radial loads, as they can cause contact between roller elements and the raceway region.
Innovation Solution
A bearing assembly with a novel drain hole design featuring a parti-circular raceway with displaced origins and an annular groove, where apertures are positioned to avoid contact with spherical rollers, allowing for improved oil drainage and reduced thermal energy generation by aligning with the intersection of the first and second surfaces, thus avoiding contact and enhancing compatibility with oil film dampers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If central outer ring drain orifices are used, then oil drainage is achieved, but compatibility with oil film dampers is reduced and device complexity increases
Solution Approach 1:
The drain aperture is repositioned from the traditional central location on the outer ring to the inner radial surface of the outer ring, effectively moving the drainage function to a different spatial dimension. This relocation allows the drain to exit through the inner surface rather than the outer surface, eliminating interference with oil film damper components that are disposed radially outside the bearing.
2Ease of manufacture
If central outer ring drain orifices are used, then oil drainage is achieved, but reliability decreases under extreme radial loads due to potential contact between rollers and raceway
Solution Approach 1:
By relocating the drain aperture to the inner radial surface and positioning it within the raceway geometry, the drainage function is achieved without creating protrusions or irregularities on the outer ring that would interfere with roller element movement under extreme radial loads.
Solution Approach 2:
The drain aperture is specifically positioned within the raceway region on the inner radial surface, creating a localized drainage solution that does not affect the overall structural integrity or load-bearing characteristics of the outer ring. The aperture is strategically placed to avoid creating stress concentration points that would compromise reliability under extreme conditions.
3Reliability
If excessive volume of oil is present in bearing cavity, then lubrication is maintained, but thermal energy generation increases due to oil churning
Solution Approach 1:
The drain aperture extracts excess lubricating oil from the bearing cavity at strategic locations on the inner radial surface, removing the harmful excess oil volume that would otherwise churn and generate thermal energy during high-speed rotation, while maintaining sufficient oil for lubrication.
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
The new design enhances oil drainage efficiency, reduces thermal energy generation, and improves compatibility with oil film dampers, minimizing the risk of damage and complexity, thereby optimizing performance and reliability in gas turbine engines.
Implementation Method 1
a lubricant disposed relative to the balls to reduce friction losses
Implementation Method 2
the lubricating oil itself can also be a factor in the generation of thermal energy... the oil operates as a coolant
Data Source
Figure 1~2
Figure 3~4
Figure 4A~4B
AI summary
A bearing assembly having an axially extending axis of rotation is provided having an inner ring (72), an outer ring (74), and a plurality of bearing elements (70). The plurality of bearing elements (70) are disposed between the inner ring (72) and the outer ring (74). The outer ring (74) includes an outer radial surface (80), an inner radial surface (82), and a raceway (88) disposed in the inner radial surface (82). The raceway (88) is defined by a first surface (90) and a second surface (92), and the first surface (90) intersects with the second surface (92) at a point aft of an axial midpoint of the raceway (88). The outer ring (74) includes a plurality of apertures (110) that provide a fluid passage between the raceway (88) and an exterior surface of the outer ring (74). A first end of each of the plurality of apertures (110) is substantially aligned with the intersection (108) of the first surface (90) and the second surface (92).