Guide Bearing Axial Force Adjustment in Turbomachines
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Solution Overview
Problem
Turbomachines face issues with axial force fluctuations during different flight phases, leading to bearing wear and reduced service life due to axial and radial floating of rolling elements, which existing solutions attempt to mitigate by applying air pressure, degrading efficiency.
Innovation Solution
An axial force application device using a piston supplied with pressurized oil is positioned between the stator and downstream guide bearing, consuming axial clearance and maintaining axial support, while not altering radial load uptake or increasing friction, and can be adjusted for varying operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air pressure is applied on radial surfaces of the rotor to maintain axial force in the preferred direction, then the axial abutment of the rotor is maintained, but the overall efficiency of the turbomachine is degraded
Solution Approach 1:
The patent applies hydraulic pressure through a piston device acting on the downstream bearing to maintain axial force in the preferred direction. This replaces the less efficient pneumatic (air pressure) system with a hydraulic system that can generate the required axial force without compromising turbomachine efficiency, as hydraulic systems are more energy-efficient and can be integrated into the existing lubrication oil circuit.
Solution Approach 2:
The patent introduces a piston device as an intermediary mechanism between the hydraulic pressure source and the rotor bearing. This intermediary translates hydraulic pressure into controlled axial force application on the bearing, allowing precise control of the axial abutment force while avoiding direct application of compressed air that would degrade overall system efficiency.
2Reliability
If air pressure is used to maintain axial force direction, then bearing wear is reduced, but the complexity of the system increases due to additional components
Solution Approach 1:
The patent utilizes the existing lubrication oil circuit of the turbomachine to provide hydraulic pressure to the piston device. This multi-functional approach allows the lubrication system to serve both its original purpose (bearing lubrication) and the new function (providing hydraulic pressure for axial force control), thereby avoiding additional complexity that would arise from creating a separate pneumatic system with compressors, valves, and control mechanisms.
Solution Approach 2:
The system uses the turbomachine's own lubrication oil circuit to generate the hydraulic pressure needed for axial force control. The lubrication pump that already exists in the system provides the pressure source, eliminating the need for external pneumatic systems and reducing overall device complexity while still protecting bearing service life.
3Reliability
If compressed air is taken from the compressor flowpath to maintain axial abutment, then the axial force is maintained, but the combustion efficiency is reduced
Solution Approach 1:
The patent transitions from using compressed air (pneumatic system) to using hydraulic pressure from the lubrication oil circuit. This eliminates the need to divert compressed air from the compressor flowpath, ensuring that all compressed air remains available for combustion processes and maintaining optimal combustion efficiency and productivity.
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 maintains consistent axial force direction, reducing bearing wear and maintaining efficiency by minimizing the impact on turbomachine design and operational performance, avoiding the need for additional components and air usage.
Implementation Method 1
A force application device is arranged between the stator and a guide bearing of said low-pressure shaft, said force application device comprising a piston supplied with pressurized oil
Implementation Method 2
a system for supplying pressurized oil at the piston, so as to exert an axial force on the outer ring
Data Source
AI summary
A turbomachine including a stator, a rotor mounted on a shaft, a first bearing and a second bearing downstream of the first bearing in a direction of air circulation at the inlet of the turbomachine, the first bearing forming an axial abutment linked to the stator, the second bearing including an inner ring secured to the shaft and an outer ring mounted on an arm secured to the stator, the second bearing including rolling elements in axial support on the inner ring and on the outer ring. The outer ring includes a radially extending ring portion. The turbomachine also includes an axial force application device mounted between the arm and the ring portion.