Auxiliary Bearing Centering Device for Turbomachine Rotor Stability
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Solution Overview
Problem
Conventional auxiliary bearing systems in turbomachines become unstable when the primary bearing system fails, leading to potential damage to the rotating machine during the transient event of the rotor 'dropping' onto the auxiliary bearing system.
Innovation Solution
An auxiliary bearing system comprising an inertia ring coupled to the rotating shaft and an auxiliary bearing receiver housing, with a specific arcuate surface geometry that allows for stable support and centering of the shaft, minimizing self-locking and fretting, and providing adequate clearance and contact zones to manage radial and axial forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional auxiliary bearing systems are used to support the rotor when the primary bearing system fails, then the rotor can be supported during the transient event, but the system becomes unstable and may cause damage to the rotating machine
Solution Approach 1:
The patent employs curved arcuate surfaces on both the inertia ring and the auxiliary bearing receiver housing instead of flat surfaces. The specific arcuate geometry with controlled contact angles prevents self-locking during the rotor drop transient, allowing stable rotor support while eliminating the harmful instability that causes machine damage.
Solution Approach 2:
The patent carefully controls the contact angle parameter between the arcuate surfaces to be within a specific range (greater than 0 degrees and less than or equal to 30 degrees). This parameter optimization ensures the auxiliary bearing system provides stable rotor support without becoming unstable, thereby preventing machine damage while maintaining reliability.
2Stability of the object's composition
If the inertia ring and auxiliary bearing receiver housing are designed with arcuate surfaces, then stable rotor support is achieved, but self-locking and fretting may occur between the contacting surfaces
Solution Approach 1:
The patent uses precisely engineered arcuate surfaces with controlled contact angles to maintain rotor stability while preventing the interfacing surfaces from self-locking. The curved geometry allows controlled movement during rotor drop without creating fretting wear, thus achieving stable rotor support without generating harmful self-locking effects.
Solution Approach 2:
The patent converts the potential harmful effect of surface contact during rotor drop into a beneficial controlled interaction. By designing the arcuate surfaces with appropriate contact angles, the natural friction that could cause self-locking is instead harnessed to provide stable rotor support, while the geometry prevents excessive contact pressure that would cause fretting wear.
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 proposed auxiliary bearing system effectively stabilizes the rotating shaft upon primary bearing failure, reducing the risk of damage by ensuring stable support and centering, while minimizing the risk of self-locking and fretting between the inertia ring and the auxiliary bearing receiver housing.
Implementation Method 1
The geometry of the second arcuate surface may be such that an angle between a rotational axis of the shaft and a tangent at a first point on the second arcuate surface at or adjacent the second radially extending surface is greater than an angle between the rotational axis of the shaft and a tangent at a second point on the second arcuate surface at or adjacent the axial outer surface
Data Source
AI summary
An auxiliary bearing system may include an auxiliary bearing receiver housing and an inertia ring. The auxiliary bearing receiver housing may include an axial inner surface, a first radially extending surface, and a first arcuate surface extending therebetween. The inertia ring may include an axial outer surface, a second radially extending surface, and a second arcuate surface extending therebetween. The second arcuate surface may have a radial outer end adjacent the second radially extending surface and a radial inner end adjacent the axial outer surface. The inertia ring may define a first angle between the axis of rotation of the shaft and a first tangent at a first point on the second arcuate surface adjacent the radial outer end, and a second angle between the axis of rotation of the shaft and a second tangent at a second point on the second arcuate surface adjacent the radial inner end.