Pressure-Chamber Bearing Structure for Thrust Load Equalization
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Solution Overview
Problem
Gas turbine engines face challenges in balancing axial thrust loads between bearings, leading to potential skidding and failure due to uneven loading, especially during periods of high power output when thrust loads are maximum.
Innovation Solution
A bearing structure with axially slidable outer races and compliant elements, including a rigid diaphragm connected to a flexible element, allows for adjustable axial spacing and additional axial load distribution between bearings, using pressure chambers and valved inlets/outlets to maintain optimal loading, and load sensors for feedback control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If two or more bearings are arranged adjacent one another to share the thrust load, then the thrust capability is improved, but uneven loading between bearings causes under-loading of one set of rolling elements leading to skidding and bearing failure
Solution Approach 1:
The patent introduces a dynamic load balancing mechanism where a movable outer race and compliant elements (springs or elastomeric materials) allow automatic adjustment of load distribution between bearings. The system transitions from static to dynamic load sharing, enabling the bearings to adaptively balance thrust loads during operation and prevent under-loading conditions that cause skidding and failure.
2Reliability
If additional axial load is induced on under-loaded bearings, then the thrust load sharing becomes more equal, but the device complexity increases due to pressure chambers and compliant elements
Solution Approach 1:
The patent merges multiple functions into integrated components: the movable outer race serves both as a structural element and a load-distribution mechanism; compliant elements simultaneously provide mechanical support and load-balancing functionality; pressure chambers combine fluid pressure application with structural support. This functional integration achieves load balancing while minimizing the number of separate components.
Solution Approach 2:
The patent employs pneumatic or hydraulic pressure chambers to apply controlled axial forces on the movable outer race, enabling precise adjustment of load distribution between bearings. By using fluid pressure instead of complex mechanical adjustment mechanisms, the system achieves reliable load balancing with simpler actuation.
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 solution ensures more equal sharing of thrust loads between bearings, reducing the risk of skidding and failure by maintaining axial loads above a predetermined minimum, thereby enhancing bearing performance and reducing vibration.
Implementation Method 1
By providing a first outer race that is axially slidable relative to the second outer race upon an increase in pressure in the pressure chamber
Implementation Method 2
When the pressure in the first or second pressure chamber increases, the respective compliant element is forced in one direction with the rigid diaphragm being forced in the opposing direction
Data Source
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AI summary
The present invention provides a bearing structure comprising a first bearing (2) having a first inner race (3), a first outer race (4) and a first set of rolling elements (5) housed between the first inner race (3) and the first outer race (4) and a second bearing (6) having a second inner race (7), a second outer race (8) and a second set of rolling elements (9) housed between the second inner race (7) and the second outer race (8). A housing (24) surrounds the first bearing (2). A first compliant element (26) is fixedly connected to the first outer race (4). A rigid diaphragm (28) is fixedly connected at its radially inner end to the first outer race (4) at a position spaced from the connection between the first compliant element (26) and the first outer race (4). The diaphragm (28) is connected with a flexible element (28) to the housing (24) at its radially outer end. The first compliant element (26), first outer race (4) and diaphragm (28) define together with a casing (35) a pressure chamber (33). The first outer race (4) is axially slidable relative to the second outer race (8) such that an increase in pressure in the pressure chamber (33) causes a change in axial spacing between the first and second outer races (4, 8). This induces an additional axial load on the bearings (4, 8) which helps balance thrust load sharing and avoid skidding.