Epicyclic Ring Gear Assembly for Repeatable Turbofan Balance
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Solution Overview
Problem
The spline connection between the ring gear and spline ring in epicyclic gear trains of gas turbine engines experiences wear and deflection under high loads, leading to imbalance and deterioration over time, making it difficult to achieve a repeatable balance of the turbo fan assembly.
Innovation Solution
The use of a two-piece ring gear construction with tapered bearings and radial passages for lubrication and a direct radial flow path, eliminating the need for a spline ring and reducing heat and windage, while allowing for rotational balance between the turbo fan shaft and ring gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a spline connection is used to connect the ring gear to the spline ring, then the gear train can transmit high loads, but the connection experiences wear and deflection under high loads leading to imbalance and deterioration over time
Solution Approach 1:
The patent removes the spline ring component entirely from the system. Instead of using a spline connection between the ring gear and spline ring, the invention directly connects the ring gear to the turbo fan shaft through a flange and bolt assembly, eliminating the problematic spline interface that caused wear and deflection.
Solution Approach 2:
The invention merges the functions of the ring gear and spline ring into a single integrated assembly. The ring gear is directly coupled to the turbo fan shaft flange, combining what were previously separate components into one unified structure that eliminates relative motion and wear at the connection interface.
2Ease of manufacture
If a spline connection is used between the ring gear and spline ring, then the gear train can be assembled, but radial clearance is required making it difficult to achieve repeatable balance of the turbo fan assembly
Solution Approach 1:
By integrating the ring gear directly to the turbo fan shaft through a rigid flange connection, the invention eliminates the radial clearance gap that existed between separate spline components. This unified structure allows for precise balancing of the entire turbo fan assembly as a single unit, achieving repeatable balance results.
3Power
If a spline connection is used, then the gear train can transmit power, but the connection is subject to wear under high loads and deflection
Solution Approach 1:
The patent extracts and removes the spline connection mechanism from the power transmission path. Power is transmitted directly from the ring gear teeth to the turbo fan shaft through rigid mechanical coupling via flange and bolts, eliminating the wear-prone spline interfaces while maintaining full power transmission capability.
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 enhances the structural rigidity and reduces wear, providing improved balance and reducing heat generation, thus improving the durability and efficiency of the turbo fan assembly.
Implementation Method 1
At least one tapered bearing is mounted on the fan shaft. A fan is mounted for rotation on the tapered bearing.
Implementation Method 2
The fan shaft includes at least one passage extending in a direction having at least a radial component, and adjacent the at least one tapered bearing.
Data Source
AI summary
A gas turbine engine according to an example of the present disclosure includes a propulsor section including a propulsor supported on a propulsor shaft, a turbine section including a turbine shaft, a compressor section having a plurality of compressor hubs with blades driven by the turbine shaft about an engine axis, and an epicyclic gear train interconnecting the propulsor shaft and the turbine shaft. The epicyclic gear train includes a sun gear coupled to the turbine shaft, intermediary gears arranged circumferentially about and meshing with the sun gear, a carrier and a ring gear including first and second portions. The first and second portions have axially opposed faces abutting one another at a radial interface.