Pancake Motor Planetary Gear Train Compact Design
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Solution Overview
Problem
Conventional gear motors with reduction gear assemblies are bulky and costly, making them unsuitable for installation in limited spaces, and pancake motors with direct load attachment suffer from vibration issues at high speeds.
Innovation Solution
A gear motor design featuring a planetary gear train with two ring gears positioned at both ends, replacing the conventional sun gear, where the number of teeth in the stationary and driving ring gears differs by a multiple of the planet gear assemblies, allowing for a high-speed reduction ratio and compact profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a reduction gear assembly is used to achieve low speed and high torque output, then the motor size and manufacturing cost increase
Solution Approach 1:
The patent employs a nested planetary gear structure where planet gears are arranged concentrically around a sun gear, with the entire planetary assembly nested within the motor housing. This nesting arrangement allows multiple gear reduction stages to be compactly integrated without proportionally increasing the motor's external dimensions, thereby achieving low speed and high torque output while controlling motor size.
Solution Approach 2:
The patent transitions from a conventional linear gear train arrangement to a two-dimensional planetary gear layout, where power transmission occurs in multiple directions simultaneously through the sun gear, planet gears, and ring gear. This dimensional change enables higher reduction ratios within a compact footprint, addressing the contradiction between speed reduction and motor size.
2Speed
If a reduction gear assembly is used to achieve low speed and high torque output, then the manufacturing cost increases
Solution Approach 1:
The patent combines the motor shaft and sun gear into a single integrated component, and merges the planet gear carrier with the motor housing. These merging actions reduce the total component count and eliminate separate assembly steps, thereby lowering manufacturing cost while maintaining the speed reduction function.
Solution Approach 2:
The motor housing serves multiple functions: it acts as the outer housing for the motor, the carrier for the planet gears, and the mounting structure for the ring gear. This multi-functionality reduces the number of separate parts that need to be manufactured and assembled, thereby reducing manufacturing cost.
3Volume of moving object
If the motor size is decreased for high speed and low torque output, then the manufacturing cost decreases
Solution Approach 1:
The nested planetary gear structure allows the gear reduction mechanism to be compactly integrated within the motor housing without requiring additional external space. This nesting enables small motor sizes to achieve practical torque output through gear multiplication, making compact motors economically viable.
4Volume of moving object
If a pancake motor with direct load attachment is used to achieve compact size, then vibration occurs at high speed
Solution Approach 1:
The planetary gear assembly acts as an intermediary mechanism between the motor shaft and the load. This intermediary provides mechanical decoupling that absorbs vibrations and shock loads, protecting the motor from direct vibration exposure while maintaining the compact pancake motor configuration.
5Speed
If a conventional planetary gear train with axially attached components is used, then the axial length increases causing bulkiness
Solution Approach 1:
The patent redistributes gear components from an axial arrangement to a radial arrangement. The sun gear is positioned at the center, planet gears are distributed radially around it, and the ring gear encloses them radially. This dimensional reorganization achieves high speed reduction ratios while minimizing axial length, eliminating bulkiness.
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 significantly reduces the motor's size and component count, achieving a high-speed reduction ratio while minimizing space occupation and eliminating vibration issues, resulting in a more efficient and cost-effective pancake motor configuration.
Implementation Method 1
an electric motor including an outer stator and a rotor surrounded and driven by the outer stator
Implementation Method 2
the first gear meshes the stationary ring gear, and the second gear meshes the driving ring gear
Data Source
AI summary
A gear motor for decreasing speed at a mechanical power output is provided with a housing; an electric motor including an outer stator and a rotor surrounded and driven by the outer stator; a planetary gear train including planet gear assemblies, a stationary ring gear at one end of the planet gear assemblies, and a driving ring gear at the other end of the planet gear assemblies. Each planet gear assembly includes a first gear and a second gear coaxial with and co-rotated with the first gear. The first and second gears are disposed in a carrier. The first gear meshes the stationary ring gear. The second gear meshes the driving ring gear. A driving shaft is rotatably disposed through the housing and secured to the driving ring gear as a mechanical power output.