Aircraft Turbine Gear Reducer With Split Hydrodynamic Planet Bearings
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Solution Overview
Problem
Mechanical reduction gears in turbomachines, particularly in aircraft, face challenges with the large axial dimension of satellites under significant torque and centrifugal loads, leading to high oil flow requirements and power losses due to the use of hydrodynamic bearings that extend the length of the satellite.
Innovation Solution
The use of two independent hydrodynamic bearings, one on either side of the satellite, reduces the axial dimension and oil flow requirements, while maintaining the necessary load capacity and minimizing sensitivity to misalignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hydrodynamic bearings extend the entire length of the planet gear to provide sufficient load capacity, then the load capacity is improved, but the axial size of the gearbox increases and oil flow requirements increase
Solution Approach 1:
The patent divides the single long hydrodynamic bearing into multiple shorter bearings arranged axially along the planet gear. This segmentation maintains the total bearing length required for load capacity while reducing the axial protrusion and oil flow requirements compared to a single extended bearing
2Strength
If hydrodynamic bearings extend the entire length of the planet gear, then the load capacity is improved, but the power losses increase due to higher oil flow rates
Solution Approach 1:
By segmenting the bearing into multiple shorter units, the patent reduces the total oil flow rate required compared to a single long bearing, thereby reducing power losses while maintaining sufficient load capacity through the combined effect of multiple bearings
3Length of moving object
If rolling element bearings are used to support the planet gears, then the axial size is reduced, but the load capacity becomes insufficient
Solution Approach 1:
The patent employs hydrodynamic bearings that utilize fluid pressure (oil film) to support the planet gears. This hydraulic approach provides the necessary load capacity for high-torque applications while maintaining a compact axial footprint compared to extended mechanical bearings
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 configuration reduces the axial size of the reducer, decreases oil flow rates, and enhances operational efficiency by optimizing the load capacity and reducing power losses.
Implementation Method 1
a bearing comprising a body embedded in a satellite and surrounded by a pressurized oil film. In the prior art, a satellite hydrodynamic bearing comprises a cylindrical body having an external cylindrical surface extending inside an internal cylindrical surface of the satellite. The pressurized oil film is interposed between these surfaces, preventing any contact between them.
Implementation Method 2
the bearings that support and guide the planetary gears are heavily loaded, and there is little space to integrate them without considerably increasing the gearbox's overall size. The planet gears each have a different axis of revolution and are evenly spaced on the same operating diameter around the axis of the planet gears. These axes are parallel to the longitudinal X-axis.
Data Source
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AI summary
Mechanical reducer (60') of turbomachine (1), in particular of aircraft, this reducer comprising: - a sun gear (70), - a ring gear (90), - satellites (80) which are meshed with the sun gear (70) and the ring gear (90), - hydrodynamic bearings (81') for guiding the rotation of the satellites (80), these bearings being carried by a satellite carrier (100) and comprising cylindrical bodies (81a) which are engaged in the satellites (80) and which are configured to be supplied with oil and to form oil films (H1, H2) for guidance between the bodies and the satellites, characterized in that each of the satellites (80) is guided by two hydrodynamic bearings independent of each other and arranged on either side of said plane (H).