Outer-Rotor Motor Layout for Narrow Axial Gap Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional outer rotor type motors require a large gap between the stator core and rotor housing in the rotation axis direction due to manufacturing variations, leading to increased size and misalignment of magnetic components, making miniaturization challenging.
Innovation Solution
The motor design includes a stator housing with an inner and outer peripheral portion, a rotor housing covering the stator, and a magnet supported by the rotor housing, with positioning portions to align the stator and magnet surfaces in the rotation axis direction, allowing for a narrow air gap and precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large gap is secured between the stator core and rotor housing in the rotation axis direction, then manufacturing variations are accommodated, but the motor size increases
Solution Approach 1:
Instead of having the stator and rotor positioning surfaces face each other in the rotation axis direction (conventional approach), the invention inverts the arrangement by positioning the stator's first surface at the inner side of the magnet and the magnet's supported surface at the side of the first surface, creating positioning portions that face each other in the radial direction. This inversion allows precise positioning without requiring a large axial gap.
Solution Approach 2:
The invention transitions from axial positioning (rotation axis direction) to radial positioning by introducing positioning portions on the inner peripheral portion of the stator housing and the outer peripheral portion of the rotor housing that face each other in the radial direction. This dimensional shift enables precise alignment without increasing the axial length.
2Power
If the length of the stator core in the stacking direction is changed to adjust magnetic path width, then torque constant is adjusted, but center alignment between magnet and stator core is lost
Solution Approach 1:
The invention inverts the positioning approach by moving from axial center alignment to radial positioning. The positioning portions are configured to align the magnetic components in the radial direction rather than relying on axial length matching, allowing the stator core length to be freely adjusted for torque optimization without compromising center alignment.
Solution Approach 2:
The invention separates the functions of magnetic path width adjustment and center alignment. The stator core length can be independently adjusted to achieve the desired magnetic path width and torque constant, while the positioning portions independently ensure precise radial alignment, decoupling these two previously coupled constraints.
3Length of stationary object
If positioning portions are configured to face each other in the radial direction, then miniaturization in the rotation axis direction is achieved, but positioning complexity increases
Solution Approach 1:
The positioning portions serve multiple functions: they provide radial positioning alignment, maintain the air gap between stator and rotor, and ensure concentricity of the magnetic components. This multi-functionality reduces the need for additional dedicated positioning features, keeping the overall structure simple despite the radial positioning configuration.
Data Source
AI summary
To achieve miniaturization in the rotation axis direction. A motor includes a stator housing having an inner peripheral portion and an outer peripheral portion, a stator supported by an outer peripheral portion of the stator housing, a rotor housing covering the stator housing and the stator, and a magnet supported by an outer peripheral portion of the rotor housing. The stator includes a first surface provided at an inner side of the magnet, supported by the stator housing and positioned in a rotation axis direction, and a second surface opposing an outside in the rotation axis direction. A surface of the magnet supported by the rotor housing is provided at an upper surface portion side of the stator core in the rotation axis direction.