Threaded Bearing Retainer Rings to Prevent Shaft Bearing Walking
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Solution Overview
Problem
Shaft bearings in turbomachines, such as gas turbine engines, often experience undesirable movement or 'walking' due to vibration and loading, necessitating a structure that prevents bearing movement while being easily manufactured and cost-effective.
Innovation Solution
A shaft bearing retainer assembly with a bearing and a bearing retainer subassembly, featuring first and second retainer rings with threaded engagements and a locking mechanism to secure the bearing in place, utilizing different thread pitches and locking mechanisms to inhibit relative rotation and maintain the bearing's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bearing is mounted on a shaft without a retainer mechanism, then the structure is simple and manufacturing is easy, but the bearing experiences undesirable movement or walking due to vibration and loading
Solution Approach 1:
The retainer assembly is segmented into multiple functional components: a retainer body with threaded engagement with the shaft, and a separate locking mechanism with locking elements. This segmentation allows each component to perform its specific function efficiently while maintaining overall simplicity of the assembly process.
Solution Approach 2:
The retainer body is preliminarily positioned and secured to the shaft via threaded engagement before the locking mechanism is applied. This preliminary action establishes the basic bearing retention, and the locking mechanism then reinforces this position to prevent walking during operation.
2Reliability
If a locking mechanism with multiple retainer rings is used to secure the bearing, then bearing stability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The locking mechanism is designed to be self-securing through threaded engagement and locking elements that automatically maintain bearing position without requiring external adjustment or monitoring systems. The structure itself provides the retention function.
Solution Approach 2:
Different thread pitches are used in the threaded engagement portions to optimize the mechanical characteristics of the retainer assembly. By varying thread parameters, the design achieves both secure retention and ease of assembly/disassembly.
3Reliability
If threaded engagements with different thread pitches are used in the retainer rings, then relative rotation is better inhibited, but manufacturing precision requirements increase
Solution Approach 1:
Different portions of the retainer assembly have different thread pitch characteristics optimized for their specific functions. The first threaded engagement portion has one pitch optimized for engagement with the shaft, while the second portion has a different pitch optimized for engagement with the retainer body, allowing each local region to have the quality needed for its purpose.
Data Source
AI summary
A shaft bearing retainer assembly is provided that includes an axially extending shaft, a bearing, and a bearing retainer subassembly. The shaft has first and second radial surfaces, a distal end, a bearing seat, and a retainer cavity. The bearing seat is engaged with the first radial surface and extends axially inward from the distal end. The retainer cavity is disposed in the second radial surface of the shaft and extends axially inward from the distal end. The shaft includes a first threaded surface portion disposed in the retainer cavity and a second threaded surface portion in the second radial surface. The bearing has a race mounted in the bearing seat. The bearing retainer subassembly includes first and second retainer rings. The first retainer ring is in threaded engagement with the first threaded surface portion. The second retainer ring is in threaded engagement with the second threaded surface portion.