Compound Planet Gear Layout With Elastic Torque Balancing
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Solution Overview
Problem
Existing planetary gear arrangements in wind turbines and other applications face issues with over-determination, leading to unbalanced load and uneven wear, as well as transient force shocks due to turbulent wind conditions, resulting in reduced service life and increased maintenance costs.
Innovation Solution
A compound planet gear arrangement with a ring gear, at least two planet gear units, and a sun wheel, where each planet gear unit includes a primary and secondary gear with elastic members allowing limited rotation, distributing torque evenly and absorbing shocks, thereby reducing wear and extending service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional planetary gear arrangements are used to transmit torque, then torque transmission is achieved, but over-determination occurs leading to unbalanced load and uneven wear
Solution Approach 1:
The patent introduces a dynamic element (spring) into the planetary gear arrangement, allowing the system to adapt its stiffness characteristics. This dynamic compliance enables balanced torque distribution among planet gears while maintaining structural integrity, resolving the over-determination problem without requiring complex additional components.
Solution Approach 2:
The patent changes the stiffness parameter of the gear connection by introducing elastic elements. This parameter change allows the system to transition from a rigid, over-determined structure to a compliant structure that naturally balances load distribution, improving reliability without increasing device complexity.
2Reliability
If rigid gear connections are used to maintain structural stability, then structural stability is achieved, but transient forces from turbulent wind cause shock waves and high overloads
Solution Approach 1:
The patent applies beforehand cushioning by pre-installing spring elements in the gear connection. These springs are designed to absorb transient shocks before they propagate through the system, protecting vulnerable components like bearings and gear teeth from high overloads while maintaining structural stability.
Solution Approach 2:
The patent uses flexible elastic elements (springs) within the gear connection to provide compliance. These flexible elements absorb transient forces from turbulent wind conditions, reducing shock waves and high overloads on meshing teeth and bearings, thereby improving durability without sacrificing structural integrity.
3Power
If cylindrical gears with two meshing tooth flanks are used for power transmission, then torque transmission is achieved, but the gearbox becomes large and heavy for high gear ratios
Solution Approach 1:
The patent employs nested planetary gear stages where planet gears are arranged around a sun gear, and ring gears enclose the entire planetary set. This nested configuration achieves high gear ratios (e.g., 1:25 or higher) in a compact form factor, significantly reducing gearbox size and weight compared to conventional cylindrical gear arrangements while maintaining full torque transmission capability.
Solution Approach 2:
The patent segments the torque transmission path into multiple planetary gear stages, with each stage contributing to the overall gear ratio. This segmentation allows high torque transmission to be achieved through distributed load paths rather than requiring a single large gear pair, reducing the overall size and weight of the gearbox.
4Speed
If multiple planetary gear stages are added to achieve high gear ratios, then gear ratio is improved, but the arrangement becomes over-determined and load distribution becomes unbalanced
Solution Approach 1:
The patent introduces dynamic compliance through spring elements in each planetary gear stage, allowing the system to adapt to manufacturing tolerances and load variations. This dynamic approach ensures balanced torque distribution across multiple planetary gears even at high gear ratios, preventing over-determination issues while achieving the desired speed reduction.
Solution Approach 2:
The patent changes the stiffness parameter of the planet gear connections by incorporating elastic elements. This parameter modification enables multiple planetary gear stages to operate with balanced load distribution, resolving the over-determination problem that typically arises when increasing gear ratio through additional stages.
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 compound planet gear arrangement achieves balanced load distribution, high gear ratios, and enhanced shock absorption, leading to increased durability, reduced maintenance, and improved energy efficiency in wind turbines and other applications.
Implementation Method 1
Each transmission arrangement comprises a number of elastic members which are arranged at the secondary planet gear and arranged to transmit torque between the primary planet teeth and the secondary planet teeth
Implementation Method 2
Each planet gear unit comprise a shock absorbing transmission arrangement which is arranged to allow a limited elastic rotation of the secondary planet teeth relative to the primary planet teeth
Data Source
Figure 1a~1b
Figure 2~3
Figure 4~5
AI summary
A compound planet gear arrangement (100, 200, 300, 400) having a ring gear (110, 210, 310, 410), at least two planet gear units (120, 220, 329, 429) and a sun wheel (130, 230, 330, 430). Each planet gear unit comprise a primary planet gear (121, 221, 321, 421) with primary planet teeth meshing with the ring gear and a secondary planet gear (122,222, 322, 422) with secondary planet teeth meshing with the sun wheel. The secondary planet gear is axially connected with the primary planet gear and has a diameter which is larger than the diameter of the primary planet gear Each planet gear unit (120, 220, 320,420) comprises a shock absorbing transmission arrangement (20) which is arranged to allow a limited elastic rotation of the secondary planet teeth relative to the primary planet teeth. A drive train arrangement comprising such a compound planet gear arrangement is also disclosed.