Compound Planet Gear Assembly for Turbo Machine Thrust Balance
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Solution Overview
Problem
Inefficient gear assemblies in turbo machines lead to mechanical and thermal losses, limiting fan and turbine speed efficiency improvements due to inefficiencies in power and torque transfer.
Innovation Solution
A thrust balancing gear assembly with a compound planet gear system, featuring axially adjacent first and second planet gears connected through a spindle, forming helical gear meshes at different helix angles, which reduces thrust bearing size and loading, and mitigates thrust balance issues by offsetting turbine thrust loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional gear assembly is used for power and torque transfer between fan and turbine, then the fan and turbine can rotate at different speeds, but mechanical and thermal losses occur at the plurality of gears reducing efficiency
Solution Approach 1:
The patent combines two planet gears (first and second planet gears) into a single compound planet gear assembly that operates between the sun gear and ring gear. This merging reduces the total number of gear interfaces from multiple separate planet gears to a unified compound structure, thereby reducing mechanical losses at gear meshes and improving overall power and torque transfer efficiency.
Solution Approach 2:
The compound planet gear serves multiple functions simultaneously: it transfers power from the sun gear to the ring gear, provides thrust balancing through its dual-gear structure, and enables counter-rotating operation. This multi-functionality reduces the need for additional separate components, minimizing mechanical losses and improving efficiency.
2Power
If multiple planet gears are used in the gear assembly, then power and torque transfer is achieved, but the thrust bearing size and loading increase
Solution Approach 1:
The compound planet gear assembly uses the first and second planet gears arranged in opposition to each other, with their gear meshes generating opposing thrust forces. This counterbalancing arrangement cancels out axial thrust loads, significantly reducing the loading on thrust bearings and allowing for smaller bearing sizes while maintaining power transfer capability.
Solution Approach 2:
The patent employs helical gears with opposite helix angles in the compound planet gear assembly. The first planet gear has a helix angle in one direction while the second planet gear has a helix angle in the opposite direction, creating asymmetric thrust forces that balance each other and reduce net axial loading on bearings.
3Device complexity
If conventional single planet gears are used, then the gear assembly structure is simpler, but thrust balance issues arise and turbine thrust loads are not offset
Solution Approach 1:
By merging two planet gears into a single compound planet gear assembly with opposing helical gears, the patent achieves thrust balance within a unified structure. This approach maintains relative structural simplicity while providing inherent thrust cancellation, improving reliability without significantly 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
The gear assembly enhances efficiency, decreases power and torque transfer losses, and improves durability by balancing thrust loads, allowing for smaller thrust bearings and reduced fluid flows, thereby improving counter-rotating turbine engine performance.
Implementation Method 1
each of the input gear, the output gear, the first planet gear, and the second planet gear defines a helical gear mesh arrangement
Implementation Method 2
the output gear and the second planet gear each define different pitch diameters relative to one another... balancing thrust loads
Data Source
AI summary
A thrust balancing gear assembly for a turbo machine is provided. The gear assembly includes an input gear connected to an input drive shaft, an output gear connected to an output drive shaft, and a compound planet gear including a first planet gear and a second planet gear each connected to one another and positioned in axially adjacent arrangement. The first planet gear is connected to the input gear at a first interface and the second planet gear is connected to the output gear at a second interface.