Compact Motor Assembly with Inverted Ring Gear Drive
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Solution Overview
Problem
Conventional gearmotors with planetary gear systems are expensive, noisy, and have a large axial length, limiting their application in compact designs and are restricted to large gear ratios.
Innovation Solution
A motor assembly with a rotor, stator, and gear assembly that includes a drive gear, ring gear, intermediate gear, and carrier, where the ring gear is rotatable relative to the carrier and stator, allowing for a compact axial profile and adaptable gear ratios, suitable for use in automated guided vehicles and overhead fans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a planetary gear system is used in a conventional gearmotor, then the gear ratio can be increased, but the axial length becomes too large for compact applications
Solution Approach 1:
The patent inverts the conventional planetary gear arrangement by making the ring gear the rotating output element rather than the sun gear. The carrier is fixed to the stator housing, and the ring gear rotates relative to the carrier, achieving high gear ratios in a compact axial footprint. This inversion allows the gear train to deliver large reduction ratios without increasing axial length.
2Force
If a planetary gear system is used in a conventional gearmotor, then torque multiplication is achieved, but noise levels become excessive
Solution Approach 1:
The patent introduces an intermediate gear as a mediator between the drive gear and the ring gear. This intermediate gear distributes the meshing interactions across multiple gear pairs, smoothing out the torque transmission and reducing the impulsive noise characteristic of direct planetary gear engagements. The intermediate gear acts as a buffer that moderates the mechanical interactions.
3Area of moving object
If a planetary gear system is used in a conventional gearmotor, then compact radial dimensions are achieved, but the overall device complexity and cost increase
Solution Approach 1:
The carrier serves multiple functions: it supports the intermediate gear, provides a mounting structure for bearings, and acts as a fixed reference element (when fixed to the stator). The ring gear simultaneously serves as both a gear element and the output shaft. This multi-functionality reduces the number of separate components needed, simplifying the overall structure while maintaining compact radial dimensions.
4Adaptability or versatility
If a planetary gear system is used in a conventional gearmotor, then high gear ratios are achieved, but the manufacturing cost becomes prohibitive
Solution Approach 1:
The patent segments the gear train into distinct modular components: a drive gear, an intermediate gear, and a ring gear, each mounted on separate bearings. This segmentation allows for simplified manufacturing of individual gear components using standard machining processes, avoiding the complex precision requirements of conventional planetary gear sets. The modular structure enables easier assembly and maintenance.
Data Source
AI summary
An electric motor assembly includes a rotor, a stator, and a gear assembly. The gear assembly includes a drive gear, a ring gear, and an intermediate gear disposed between and engaging each of the drive gear and the ring gear. The gear assembly further includes a carrier supporting the intermediate gear and being fixed relative to the stator so as to be stationary relative thereto. The ring gear is rotatable relative to the carrier and the stator.