Flexible Ball Bearing Support for Thermal Preload Stability
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Solution Overview
Problem
Preloaded ball bearings in gas turbine engines are prone to premature failure due to thermal growth causing increased axial preload beyond the capability of the bearings, leading to overloading and failure.
Innovation Solution
A preloaded ball bearing assembly with a flexible support integrally formed with the preload bearing assembly, positioned between the primary and preload bearing assemblies, which includes a flange extending from the static structure to axially position the primary bearing assembly, and features such as wave segments, spiral rings, or solid beams to manage thermal growth and maintain preload stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a preloaded ball bearing assembly is used to reduce radial and axial displacement and increase moment stiffness, then bearing performance is improved, but thermal growth causes increased axial preload that overloads the bearing and leads to premature failure
Solution Approach 1:
The patent changes the physical state of the support structure from rigid to flexible, allowing it to deform elastically under thermal expansion. This parameter change enables the system to accommodate thermal growth without generating excessive preload forces on the bearing, thereby resolving the contradiction between improved bearing performance and bearing overload.
Solution Approach 2:
The patent explicitly addresses thermal expansion by designing a flexible support that can expand axially with thermal growth. The support structure is engineered to have controlled flexibility that allows it to expand without transferring excessive forces to the bearing, directly addressing the thermal expansion issue that causes bearing overload.
2Stability of the object's composition
If a rigid support structure is used to maintain bearing position, then structural stability is improved, but thermal growth causes gap closure and bearing overload
Solution Approach 1:
The patent employs a flexible support structure that can be conceptualized as a flexible element capable of controlled deformation. This flexible support maintains bearing position stability through its elastic properties while simultaneously accommodating thermal expansion, preventing gap closure and bearing overload that would occur with a rigid structure.
Solution Approach 2:
The patent transitions from a static rigid support to a dynamic flexible support that can adapt its stiffness characteristics. The flexible support dynamically adjusts to thermal conditions, maintaining structural stability at operating temperatures while preventing the harmful effects of thermal growth that would occur with a fixed rigid structure.
3Reliability
If thermal growth is accommodated with a flexible support, then bearing overload is prevented, but the complexity of the bearing assembly increases
Solution Approach 1:
The flexible support structure is designed to automatically accommodate thermal expansion without requiring external control systems or adjustment mechanisms. The inherent elasticity of the support provides self-regulating load management, preventing bearing overload through its passive mechanical properties rather than active control, thereby limiting the increase in system complexity.
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 flexible support design ensures the preloaded ball bearing assembly remains insensitive to thermal growth, reducing the risk of bearing overload and improving durability by maintaining a consistent load distribution across various operating conditions.
Implementation Method 1
a flexible support disposed between the primary bearing assembly and the preload bearing assembly
Data Source
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AI summary
A preloaded ball bearing assembly (60) includes a primary bearing assembly (62) disposed between a rotating component (68) and a static structure (70). The assembly also includes a preload bearing assembly (64) disposed in contact with the rotating component. The assembly further includes a flexible support (100; 200; 300) disposed between the primary bearing assembly and the preload bearing assembly.