Variable-Length Squeeze Film Damper Bearing for Dual-Speed Vibration Damping
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Solution Overview
Problem
Existing roller bearings with oil film compression dampers in turbomachines provide limited vibration damping across a specific range of engine speeds, failing to effectively address damping needs across different operating conditions.
Innovation Solution
A roller bearing with a hydraulically or pneumatically controlled movable segment that modifies the geometry of the damping oil film cavity, allowing two distinct damping values by adjusting the cavity length through a two-position sealing mechanism, controlled by actuators or electromagnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cavity length is fixed, then the damping value is stable for a specific engine speed range, but the damping performance deteriorates when operating conditions change
Solution Approach 1:
The cavity length is made variable through a movable segment that can shift between a first position (extending into the cavity to reduce length) and a second position (retracted to maintain full length). This dynamic adjustment allows the damping system to adapt to different engine operating conditions, resolving the contradiction between stable damping performance and adaptability to varying speeds.
Solution Approach 2:
The physical parameter of cavity length is changed based on operating conditions. By controlling the movable segment's position, the system adjusts the cavity length parameter to optimize damping performance for different engine speed ranges, thereby achieving both stability within ranges and adaptability across ranges.
2Reliability
If a fixed damping system is used, then the device complexity is low, but the damping effectiveness is limited to a narrow speed range
Solution Approach 1:
The movable segment is designed to move automatically in response to pressure changes in the cavity, without requiring external actuators or complex control systems. The segment shifts to the first position when cavity pressure increases and returns to the second position when pressure decreases, allowing the system to self-regulate damping based on operating conditions while minimizing added complexity.
3Reliability
If the cavity length is reduced, then the damping value decreases for high-speed operation, but the cavity volume is compromised
Solution Approach 1:
The movable segment dynamically adjusts the effective cavity length based on operating conditions. During high-speed operation, the segment moves to the first position to reduce cavity length and optimize damping value. During low-speed operation, the segment returns to the second position to maintain full cavity volume. This dynamic adjustment resolves the contradiction between optimizing damping value and preserving cavity volume.
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
Enables effective vibration damping across two engine speed ranges by providing adjustable damping values, enhancing the bearing's performance across varying operating conditions.
Implementation Method 1
The internal cavity 17 is pressurized with oil, so that in the event of an unbalance of the rotating element 14, the internal sleeve 12 shifts off-center from the axis AX in the direction of the unbalance due to the centrifugal forces generated by this unbalance. During operation, this offset rotates with the rotating element. The hydraulic pressurization of the cavity 17 thus dampens the offset to limit the vibrations caused by the unbalance.
Data Source
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AI summary
The invention relates to a bearing (21) for a turbine engine comprising an oil film compression damper, including an inner sleeve (22) intended to receive an outer ring of a rolling bearing, an outer sleeve (23) surrounding the inner sleeve (22) and delimiting, with this inner sleeve (22), an axisymmetric cavity (27) supplied hydraulically in order to form a film of damping oil, this cavity (27) being closed at its ends by two segments (24, 26). According to the invention, the cavity (27) comprises a first portion (31) and a second portion (32) separated from one another by a movable segment (29) able to occupy a closed position in which it forms a controlled sealing barrier between the two portions (31, 32), and an open position in which the two portions (31, 32) communicate with one another, and it is the first portion (31) that is supplied hydraulically to form the film of oil.