Aircraft Gearbox Assembly With Double Helical Gears for Torque Stability
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Solution Overview
Problem
Existing aircraft propulsion systems' speed-changing gearbox assemblies face limitations in power output and torque stability due to conventional gear patterns, which affect the efficiency and reliability of reducing rotational speeds for propeller operation.
Innovation Solution
The proposed assembly incorporates a sun gear with a double helical gear pattern and planet gears with monolithic main, first lateral, and second lateral gears, along with first and second ring gears featuring spur gear patterns, to enhance loading capacity and reduce torque fluctuation, while a planet carrier with journal bearings supports axial movement and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional gear patterns are used in the gearbox assembly, then the structural design is simpler, but the power output and torque stability are limited
Solution Approach 1:
The planet gear is segmented into multiple gear patterns (first double helical gear pattern, second double helical gear pattern, and third spur gear pattern) that are axially spaced and engage with different ring gears. This segmentation allows each gear pattern to contribute to power transmission independently, increasing the overall power output capacity of the gearbox assembly without requiring a complete redesign of the fundamental planetary gear structure.
Solution Approach 2:
The invention transitions from conventional single-plane gear engagement to multi-plane engagement by arranging gear patterns in the axial dimension. The first and second double helical gear patterns engage with ring gears at different axial positions, effectively utilizing the axial dimension to increase power transmission capacity within the same radial envelope, thereby increasing power output without proportionally increasing device complexity.
2Stability of the object's composition
If conventional gear patterns are used in the gearbox assembly, then the manufacturing process is easier, but the torque stability is insufficient
Solution Approach 1:
The planet gear is divided into multiple gear patterns (first double helical, second double helical, and third spur patterns) that engage with different ring gears axially spaced from each other. This segmentation distributes torque transmission across multiple engagement points, reducing torque fluctuation and improving torque stability. Each gear pattern can be manufactured using standard gear manufacturing processes, maintaining ease of manufacture while achieving superior torque stability.
Solution Approach 2:
The invention employs different gear pattern types (double helical and spur) with distinct geometric parameters to engage with respective ring gears. The double helical patterns provide smooth torque transmission with reduced shock, while the spur pattern provides additional engagement points. By changing gear pattern parameters and types across different axial positions, the system achieves improved torque stability without significantly complicating the manufacturing process, as each pattern can be manufactured using appropriate standard techniques.
3Force
If multiple ring gears with different gear patterns are used, then the loading capacity increases, but the device complexity increases
Solution Approach 1:
The invention merges multiple gear transmission paths into a single compact planetary gear assembly. The planet gear combines first double helical, second double helical, and third spur gear patterns in one component, while the ring gears are integrated with the planet carrier structure. This merging of multiple transmission paths into unified components increases loading capacity by distributing forces across multiple engagement points while avoiding the complexity of separate transmission systems.
Solution Approach 2:
The planet gear serves multiple functions simultaneously by incorporating different gear patterns that engage with different ring gears. The first double helical pattern transmits torque to the first ring gear, the second double helical pattern transmits torque to the second ring gear, and the third spur pattern provides additional engagement. This multi-functionality allows a single planet gear component to handle multiple loading paths, increasing overall loading capacity without proportionally increasing device complexity.
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 increases power output within a given geometrical envelope and improves torque stability, enabling more efficient propulsion by maintaining reduced rotational speeds for propellers, thus enhancing the overall performance of aircraft propulsion systems.
Implementation Method 1
The sun gear includes a first double helical gear pattern. Each planet gear of the plurality of planet gears includes a main gear, a first lateral gear, and a second lateral gear. The main gear includes a second double helical gear pattern engaged with the first double helical gear pattern. The first lateral gear is engaged with the first ring gear. The second lateral gear is engaged with the second ring gear.
Data Source
AI summary
An assembly for an aircraft propulsion system includes an output shaft and a gear assembly. The gear assembly is configured to drive rotation of the output shaft. The gear assembly includes a sun gear, a plurality of planet gears, a first ring gear, and a second ring gear. The sun gear is rotatable about a rotational axis. The sun gear includes a first double helical gear pattern. Each planet gear of the plurality of planet gears includes a main gear, a first lateral gear, and a second lateral gear. The main gear includes a second double helical gear pattern engaged with the first double helical gear pattern. The first lateral gear is engaged with the first ring gear. The second lateral gear is engaged with the second ring gear. The first ring gear is axially spaced from the second ring gear relative to the rotational axis.