Multi-Bearing Shaft Assembly with Eccentric Alignment and Damping
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Solution Overview
Problem
Maintaining alignment and operational efficiency of multiple bearings on a shaft in gas turbine engines is challenging due to tolerance variations, which complicates assembly and can lead to misalignment and increased vibrations.
Innovation Solution
A bearing assembly comprising a combination of hard-mounted and resiliently mounted bearings, including a fourth bearing with an eccentric outer race that can be adjusted to ensure proper alignment, along with a method of assembly that involves sequential mounting and adjustment to address radial offset, allowing for effective shaft alignment and reduced vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple bearings are mounted on a shaft to maintain alignment and operational speed range, then the shaft alignment and operational efficiency are improved, but the assembly difficulty increases due to tolerance variations
Solution Approach 1:
The patent employs bearings with different mounting characteristics (hard-mounted vs. resiliently mounted) to change the operational parameters of the bearing assembly. This allows the system to accommodate tolerance variations while maintaining proper shaft alignment, resolving the contradiction between improved alignment and increased assembly difficulty.
Solution Approach 2:
By incorporating resiliently mounted bearings with dampers, the patent introduces dynamic elements that can adapt to misalignment conditions. These resilient mountings allow for movement and adjustment, making the assembly process more forgiving of tolerance variations while maintaining operational alignment.
2Reliability
If multiple bearings are mounted on a shaft to maintain alignment, then the shaft alignment is improved, but the vibrations increase due to misalignment
Solution Approach 1:
The patent introduces dampers as intermediary elements between the resiliently mounted bearings and the engine structure. These dampers act as mediators that absorb and reduce vibrations caused by misalignment, while still allowing the bearings to maintain proper shaft alignment through their resilient mounting.
Solution Approach 2:
The patent converts the potentially harmful effect of misalignment-induced vibrations into a benefit by using resiliently mounted bearings with dampers. These components are designed to absorb and dissipate vibration energy, transforming the harmful vibrational forces into controlled damping actions that protect the engine structure.
3Object-generated harmful factors
If a combination of hard-mounted and resiliently mounted bearings is used, then the vibrations are reduced, but the device complexity increases
Solution Approach 1:
The patent applies different mounting qualities to different bearings in the assembly - some are hard-mounted while others are resiliently mounted with dampers. This local differentiation allows vibration reduction at critical locations without requiring all bearings to be complex resilient mountings, thus balancing vibration control with overall 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 solution ensures proper alignment of the shaft, reduces vibrations, and maintains the shaft within desired operational speed ranges, enhancing the overall efficiency and reliability of the gas turbine engine.
Implementation Method 1
at least one second bearing mounted between the shaft and the static engine structure, wherein the at least one second bearing includes a damper
Implementation Method 2
at least one third bearing mounted between the shaft and the static engine structure, wherein the at least one third bearing includes a resilient member in parallel combination with a viscous damper
Implementation Method 3
at least one fourth bearing that is hard mounted directly between the shaft and the static engine structure, wherein the at least one fourth bearing includes an inner race that has a first centerline and an eccentric outer race that has a second centerline that is radially offset from the first centerline
Data Source
Figure 1
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Figure 4~5
AI summary
A method and an apparatus includes a static engine structure, at least one shaft (40) that rotates relative to the static engine structure, and a bearing assembly (60) that supports the shaft (40). The bearing assembly (60) includes at least one first bearing (62) hard mounted directly between the shaft (40) and the static engine structure and at least one second bearing (64) mounted between the shaft (40) and the static engine structure. The at least one second bearing (64) includes a damper (116). Also included is at least one third bearing (66) that is mounted between the shaft (40) and the static engine structure, wherein the at least one third bearing (66) includes a resilient member (118).