Compound Planetary Gear Layout for High Reduction Ratios
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Solution Overview
Problem
Existing planetary gear trains used in rotorcraft transmissions are heavy, require significant maintenance, and have limited reduction ratios due to the mechanical advantage being limited by the diameter of the planet gears, which increases system weight and envelope size.
Innovation Solution
A planetary gear system that eliminates the need for a carrier to interconnect planet gears, allowing for a reduced weight and lower maintenance design by using compound planet gears with multiple stages and a fixed gear to achieve higher reduction ratios without the need for large diameter planet gears, thereby allowing for more efficient torque and rotational output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large diameter planet gears are used to achieve high reduction ratios, then the reduction ratio increases, but the system weight and envelope size increase
Solution Approach 1:
The patent implements nested compound planet gears where multiple gear stages are concentrically arranged around a common axis. Each planet gear assembly includes multiple gear stages with different pitch diameters that mesh with corresponding sun and ring gears, effectively nesting multiple reduction stages within a compact radial space. This allows achieving high reduction ratios without increasing the overall system envelope or weight proportionally.
Solution Approach 2:
The patent transitions from single-stage planet gears to multi-stage compound planet gears, adding a dimensional aspect to the gear arrangement. By stacking multiple gear stages concentrically along the radial dimension, the system achieves higher reduction ratios within the same footprint, effectively utilizing three-dimensional space rather than increasing radial diameter.
2Productivity
If large diameter planet gears are used to achieve high reduction ratios, then the reduction ratio increases, but the system envelope size increases
Solution Approach 1:
The patent implements nested compound planet gears where multiple gear stages are concentrically arranged around a common axis. Each planet gear assembly includes multiple gear stages with different pitch diameters that mesh with corresponding sun and ring gears, effectively nesting multiple reduction stages within a compact radial space. This allows achieving high reduction ratios without increasing the overall system envelope or weight proportionally.
Solution Approach 2:
The patent transitions from single-stage planet gears to multi-stage compound planet gears, adding a dimensional aspect to the gear arrangement. By stacking multiple gear stages concentrically along the radial dimension, the system achieves higher reduction ratios within the same footprint, effectively utilizing three-dimensional space rather than increasing radial diameter.
3Power
If traditional planetary gear trains are used with carrier and bearing assemblies, then torque transmission is achieved, but maintenance requirements increase
Solution Approach 1:
The patent eliminates the carrier component and bearing assemblies from the traditional planetary gear train. Instead of using a carrier to hold and support the planet gears via bearings, the invention allows the planet gears to rotate freely on their axes while maintaining mesh engagement with sun and ring gears. This extraction of the carrier and bearing subsystem removes the components requiring lubrication and periodic maintenance.
Solution Approach 2:
The planet gears in the patent are designed to self-support their rotational motion without external bearing support. The gear geometry and meshing arrangement provide inherent stability and load distribution, allowing the system to operate without periodic lubrication or maintenance of bearing assemblies.
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 design achieves lighter weight, lower maintenance, and larger reduction ratios while minimizing system envelope size, enhancing the efficiency and performance of rotorcraft transmissions by distributing torque loads effectively through compound planet gears without relying on large planet gears.
Implementation Method 1
at least one compound planet gear (106) meshed between the at least one non-fixed annular gear and the at least one non-fixed sun gear
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A planetary gear system (100), comprising: a plurality of compound planet gears (106) configured to orbit around a primary rotation axis (110) and each including three gear stages; a first non-fixed annular gear (152) configured to rotate about the primary rotation axis (110) and operatively meshed with one of the three gear stages; a second non-fixed annular gear (154) configured to rotate about the primary rotation axis (110) and operatively meshed with one of the three gear stages; a fixed annular gear (132) with a central axis that is coaxial with the primary rotation axis (110) and operatively meshed with one of the three gear stages; and a non-fixed sun gear (104) configured to rotate about the primary rotation axis (110) and operatively meshed with one of the three gear stages.