Two-Stage Planetary Gear Noise Reduction via Segmented Engagement Ratios
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Solution Overview
Problem
Conventional reduction gears with planetary mechanisms face challenges in balancing engagement ratio and strength, leading to mechanical noise and potential gear weakness, especially when high torque is required, as seen in electric gate motors.
Innovation Solution
A two-stage planetary gear mechanism with helical gears, where the engagement ratio of the first stage is set to 3.0 or more, and the second stage has a lower engagement ratio, combined with a resin case design that includes a reinforcing component to enhance central axial strength, reducing noise and maintaining gear strength without increasing size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the engagement ratio of the planetary gear mechanism is increased to reduce mechanical noise, then the quietness is improved, but the strength of the gears decreases
Solution Approach 1:
The patent divides the single-stage planetary gear mechanism into two stages, with the first stage having a high engagement ratio (3.0 or more) for noise reduction and the second stage having a lower engagement ratio for strength assurance. This segmentation allows each stage to be optimized for its specific function, resolving the contradiction between noise reduction and strength maintenance.
Solution Approach 2:
The patent applies different engagement ratios to different stages of the planetary gear mechanism based on their specific functional requirements. The first stage uses a high engagement ratio locally optimized for noise reduction, while the second stage uses a lower engagement ratio locally optimized for strength, thereby resolving the global contradiction through localized optimization.
2Object-affected harmful factors
If the engagement ratio is set to 3.0 or more to reduce mechanical noise, then the quietness is improved, but the gear strength may not be secured
Solution Approach 1:
The patent segments the gear reduction function into two stages, assigning the high engagement ratio (3.0 or more) to the first stage for noise reduction while assigning the second stage with a lower engagement ratio for reliability assurance. This segmentation enables the system to achieve both noise reduction and reliability simultaneously.
Solution Approach 2:
The patent changes the engagement ratio parameter differently for each stage of the planetary gear mechanism. The first stage uses an engagement ratio of 3.0 or more for noise reduction, while the second stage uses a lower engagement ratio for reliability, thereby resolving the contradiction through parameter differentiation.
3Object-affected harmful factors
If a two-stage planetary gear mechanism is used to reduce noise, then the quietness is improved, but the device complexity increases
Solution Approach 1:
The patent merges two planetary gear mechanisms into a single integrated case structure, where both stages share common components such as the case and supporting structures. This merging approach reduces the overall complexity compared to having separate mechanisms, while still achieving the noise reduction benefits of the two-stage configuration.
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 solution effectively reduces mechanical noise while securing gear strength, improving quietness and torque handling without enlarging the gear system, and allows for cost-effective and efficient design modifications.
Implementation Method 1
two-stage planetary gear mechanisms that are provided side by side in an axial direction of the motor and are each configured of helical gears
Data Source
AI summary
A reduction gear configured to decelerate and output rotation of a motor includes two-stage planetary gear mechanisms that are provided side by side in an axial direction of the motor and are each configured of helical gears, and a case made of resin and formed into a cylindrical shape, the case incorporating the two-stage planetary gear mechanisms. At least one of an inner engagement ratio of a sun gear and a pinion gear of the planetary gear mechanism in a first stage and an outer engagement ratio of the pinion gear and a ring gear of the planetary gear mechanism in the first stage is 3.0 or more, and both the inner engagement ratio and the outer engagement ratio are larger than an engagement ratio of the planetary gear mechanism in a second stage.