Two-Piece Ring Gear Mounting for Turbofan Balance Stability
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Solution Overview
Problem
The splined 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 repeatable balance of the turbo fan assembly.
Innovation Solution
A two-piece ring gear design with radially extending flanges and a torque frame that supports the gear system, eliminating the need for a spline ring by using radially extending flanges connected with bolts and nuts, and incorporating a gutter for oil collection to reduce windage and churning, while facilitating vibration segregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a splined connection is used between the ring gear and spline ring, then the gear system can transmit torque, but the splined connection experiences wear and deflection under high loads leading to imbalance
Solution Approach 1:
The patent removes the spline ring component entirely from the design. Instead of using a splined connection between a ring gear and spline ring, the invention directly couples the ring gear to the turbo fan shaft through a flange connection with bolts, eliminating the problematic splined interface that caused wear and deflection issues.
Solution Approach 2:
The ring gear is divided into two separate portions (first portion and second portion) that are joined together. This segmentation allows for a more rigid structural configuration when combined with the flange and bolt connection to the shaft, reducing deflection under load compared to a single-piece design with splines.
2Manufacturing precision
If a spline ring is used to connect the ring gear to the turbo fan shaft, then the connection can accommodate radial clearance, but it is difficult to achieve repeatable balance of the turbo fan assembly
Solution Approach 1:
The spline ring is extracted/removed from the system. The patent replaces the complex splined connection with a simpler direct flange-to-shaft bolted connection, which eliminates the radial clearance issues inherent in splined connections and enables repeatable balancing of the turbo fan assembly.
Solution Approach 2:
The connection function is merged directly into the ring gear structure itself through the flange extension. Instead of using a separate spline ring component, the flange is integrated as part of the ring gear assembly, creating a more rigid and balanceable unified structure.
3Strength
If a traditional single-piece ring gear design is used, then the structure is simpler, but radial movement and heat generation from splines occur under high loads
Solution Approach 1:
The splined connection interface is extracted and removed entirely. By eliminating the spline-to-spline meshing, the patent removes the source of heat generation through friction and the radial movement that occurs during spline engagement, while maintaining torque transmission capability through the direct flange connection.
Solution Approach 2:
The ring gear is segmented into two portions that can be independently positioned and joined. This segmentation, combined with the direct flange connection to the shaft, creates a more rigid structure that reduces radial movement under load compared to a traditional single-piece design with splines, thereby reducing energy loss through friction.
Data Source
AI summary
A gas turbine engine includes a bypass ratio greater than about ten (10). A fan is supported on a fan shaft and has a plurality of fan blades. A gear system is connected to the fan shaft. A plurality of planetary gears and a first set of opposed angled ring gear teeth are separated from a second set of opposed angled ring gear teeth. A lubricant flow path is located axially between the first set of opposed angled ring gear teeth and the second set of opposed angled ring gear teeth. A gear system support is relative to a fixed housing facilitating segregation of vibrations. An annular channel is axially aligned with the lubricant flow path. A low pressure turbine has an inlet, an outlet, and a low pressure turbine pressure ratio greater than 5:1.