Coreless Motor with Nested Planetary Gear for Compact Assembly
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Solution Overview
Problem
Existing coreless motors with integrated speed-reducer mechanisms struggle with significant downsizing and achieving precise concentricity between the motor shaft, magnet, and outer cylinder, leading to complex assembly processes and reduced accuracy.
Innovation Solution
A coreless motor design incorporating a planetary gear unit with a cylindrical magnet and outer cylinder, where the motor shaft is supported by bearings and a pinion gear meshing with planetary gears, ensuring accurate concentricity and simplified assembly by dividing the motor into distinct units such as an outer cylinder gear unit, motor shaft unit, rotor unit, and outer lid unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor and speed-reducer mechanism are integrated in the same housing, then the number of intermediate components is reduced and assembly time is decreased, but the motor size cannot be drastically reduced
Solution Approach 1:
The planetary gear unit is nested within the magnet structure, with the sun gear positioned at the center of the magnet and planetary gears arranged around it. This nesting allows the speed-reducer mechanism to occupy the same spatial envelope as the motor, achieving compact integration without simply placing components side-by-side in the housing.
Solution Approach 2:
The patent transitions from a two-dimensional planar arrangement of components to a three-dimensional spatial configuration where the planetary gear unit is embedded within the cylindrical magnet structure. This dimensional change enables the speed-reducer mechanism to be accommodated within the motor's radial and axial dimensions, achieving compact integration.
2Volume of moving object
If the motor structure is revised to achieve further downsizing, then the entire motor length can be reduced, but the complexity of ensuring concentricity of motor shaft, magnet, and outer cylinder increases
Solution Approach 1:
The motor shaft, sun gear, and output shaft are merged into a single integrated component. This merging eliminates the need for separate alignment of multiple shafts and gears, as the planetary gear unit is directly mounted on the motor shaft, automatically ensuring concentricity between the motor shaft, magnet, and outer cylinder.
Solution Approach 2:
The integrated motor shaft-sun gear-output shaft structure serves itself to maintain concentricity. The symmetric arrangement of planetary gears around the sun gear, combined with the rigid connection to the motor shaft, automatically ensures proper alignment without requiring external adjustment mechanisms or complex assembly procedures.
3Device complexity
If the motor shaft is directly connected to the planetary gear unit, then the number of components is reduced and assembly is simplified, but the precision of gear meshing may be compromised
Solution Approach 1:
The planetary gear unit is pre-assembled with the sun gear and planetary gears positioned in their correct meshing positions before being integrated with the motor shaft. This preliminary arrangement ensures proper gear meshing geometry is established, and the subsequent integration with the motor shaft maintains this precision through the rigid connection.
Solution Approach 2:
The patent applies different quality requirements to different parts of the gear system. The sun gear and planetary gears are manufactured with high precision tooth profiles and meshing surfaces, while the connection to the motor shaft utilizes the rigid integrated structure. This local differentiation of quality requirements ensures gear meshing precision is achieved where needed without requiring high precision throughout the entire assembly process.
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 design allows for a compact motor structure with improved assembly ease and concentricity accuracy between the motor shaft, magnet, and outer cylinder, facilitating a more efficient downsizing of the motor while maintaining operational reliability.
Implementation Method 1
a coil interposed between the magnet and the outer cylinder and adapted, when energized, to rotate around the motor shaft relative to the magnet
Data Source
AI summary
A coreless motor able to be downsized and easy to be assembled and to ensure the concentricity between a motor shaft, a magnet, and an outer cylinder. The coreless motor includes an outer cylinder gear unit having an output shaft and a speed-reducer mechanism incorporated into a field assembly having a magnet fitted on an inner yoke and an outer cylinder fitted on an outer periphery of the magnet, a motor shaft unit having an inner lid rotatably supporting a motor shaft via ball bearings, a rotor unit having a circular plate attached with a commutator electrically connected to a coil, an outer lid unit having an outer lid mounted with brushes. The inner lid is incorporated in the inner yoke, the coil is incorporated in between the outer cylinder and the magnet, and the outer lid unit is attached to the rotor unit and the outer cylinder.