Helical Gear Axial Thrust Balancing via Segmented Planet Design
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Solution Overview
Problem
Conventional planetary gear assemblies often produce linear axial thrust forces during torque transfer, leading to unnecessary movement and wear within the gearset housing, which can result in inefficiencies and reduced lifespan.
Innovation Solution
The use of helical gears with specifically designed cylindrical segments having teeth at distinct helix angles, ensuring that the linear axial force produced by each helical gear is substantially zero, thereby maintaining torque transfer without axial thrust, and utilizing a stepped planet configuration to balance axial loads across gears of different sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional planetary gear assemblies are used to transfer torque, then torque transfer is achieved, but linear axial thrust forces are produced causing unnecessary movement and wear within the gearset housing
Solution Approach 1:
The patent applies parameter changes by modifying the helix angles of the cylindrical segments. Specifically, the first cylindrical segment has teeth at a first helix angle and the second cylindrical segment has teeth at a second helix angle, where these angles are specifically selected to balance the axial thrust forces. This parameter adjustment allows the gear assembly to maintain torque transfer capability while eliminating harmful axial thrust forces that cause wear and movement within the housing.
2Object-generated harmful factors
If helical gears with different helix angles are used to balance axial thrust, then axial force is reduced to substantially zero, but gear structure complexity increases with multiple cylindrical segments
Solution Approach 1:
The planet gears are segmented into multiple cylindrical segments (first cylindrical segment and second cylindrical segment), each with teeth at different helix angles. This segmentation allows each segment to contribute differently to the torque transfer and axial force generation, enabling the overall balance of axial thrust forces to substantially zero while maintaining a manageable structural complexity through modular design.
3Force
If stepped planet configuration is used to balance axial loads across gears of different sizes, then load distribution is improved, but manufacturing complexity increases
Solution Approach 1:
The stepped planet configuration implements local quality by having different cylindrical segments with different helix angles and tooth configurations tailored to specific positions and functions. This allows optimal load distribution across gears of different sizes by assigning appropriate helix angles to specific segments, while the modular segmented structure actually simplifies manufacturing compared to creating entirely different gear designs for each size variation.
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 approach ensures efficient torque transfer with minimal axial thrust, reducing wear and tear, and maintaining the integrity of the gearset by eliminating unnecessary movement within the housing, thus enhancing the longevity and performance of the planetary gear assembly.
Implementation Method 1
a first cylindrical segment having teeth that are configured to mate with teeth of an input drive shaft, the teeth of the first cylindrical segment having helical teeth disposed at a first angle; and (ii) a second cylindrical segment extending from the first cylindrical segment, the second cylindrical segment having teeth configured to mate with teeth of the ring gear, the teeth of the second cylindrical segment having helical teeth disposed at a second angle
Data Source
AI summary
A planetary gear system includes a ring gear supported by a housing, the ring gear having teeth on an inner sidewall of the ring gear, and a plurality of helical gears, each of the plurality of helical gears including a first cylindrical segment having teeth that are configured to mate with teeth of an input drive shaft, the teeth of the first cylindrical segment having helical teeth disposed at a first angle, and a second cylindrical segment extending from the first cylindrical segment, the second cylindrical segment having teeth configured to mate with teeth of the ring gear, the teeth of the second cylindrical segment having helical teeth disposed at a second angle. Advantageously, a linear axial force produced by each of the plurality of helical gears is substantially zero, which creates a thrust balancing within the planetary gear system.