Brushless Motor Stator Core Notch Design for Rotation Inhibition
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Solution Overview
Problem
Existing brushless motors face challenges in inhibiting stator core rotation without generating excessive stress, which deteriorates magnetic characteristics and increases core loss due to the need for strong compressive forces to prevent rotation.
Innovation Solution
Incorporating notch portions on the outer circumferential surface of the stator core, which allows for effective inhibition of stator core rotation without applying a strong compressive force, while maintaining the magnetic flux path and minimizing core loss by ensuring the notch width is smaller than the teeth width and not limiting the magnetic flux flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the outer circumferential surface of the yoke portion and the inner circumferential surface of the housing are both flat, then the stator core can be fixed to the housing, but a strong compressive force is required which generates stress inside the yoke portion and increases core loss
Solution Approach 1:
The invention applies curvature to the outer circumferential surface of the yoke portion by providing a凹槽 (notch portion) that creates a curved or non-flat surface profile. This curved surface allows the stator core to be fixed to the housing without requiring strong compressive forces, as the curved geometry provides mechanical interlocking or positioning features that stabilize the stator core while reducing the magnitude of fixing forces needed, thereby preventing stress-induced core loss increase.
2Stability of the object's composition
If a strong compressive force is applied to inhibit stator core rotation, then the stator core is fixed securely, but stress is generated inside the yoke portion which deteriorates magnetic characteristics
Solution Approach 1:
The curved or non-flat outer circumferential surface with a凹槽 (notch portion) provides geometric features that mechanically inhibit stator core rotation through shape complementarity with the housing, rather than relying solely on compressive force magnitude. This reduces the stress burden on the yoke portion while maintaining rotation inhibition effectiveness.
Solution Approach 2:
The凹槽 (notch portion) creates a localized feature on the outer circumferential surface that concentrates the fixation function in a specific region. This local geometric modification allows the stator core to be securely positioned and rotation-inhibited at the notch location without subjecting the entire yoke portion to high compressive stresses, thereby preserving magnetic characteristics in other regions.
3Loss of energy
If the circumferential width of the notch portion is made smaller than the teeth portion, then the magnetic flux path is maintained, but the fixation effectiveness must be sufficient
Solution Approach 1:
The凹槽 (notch portion) with circumferential width smaller than the teeth portion creates a localized fixation feature that preserves the overall magnetic flux path continuity. The localized nature of the notch allows it to provide rotation inhibition functionality without creating significant gaps or interruptions in the magnetic circuit, thereby maintaining low core loss while achieving adequate fixation stability through the geometric interlocking feature.
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 solution effectively inhibits stator core rotation and prevents an increase in core loss, maintaining magnetic efficiency and reducing stress within the yoke portion, thus enhancing the performance and size reduction capabilities of brushless motors.
Implementation Method 1
The teeth portions magnetized by an electric current flowing through the coils apply a magnetic force to the permanent magnet of the rotor, and the rotor thereby rotates
Implementation Method 2
As a counteraction to the rotation of the rotor, the teeth portions also receive a magnetic force from the permanent magnet of the rotor
Data Source
Figure 1~2
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Figure 5~6
AI summary
A brushless motor (10) includes: a stator core (11) having a cylindrical yoke portion (111) and a teeth portion (112) having a shape protruding from an inner circumferential surface of the yoke portion (111); and a rotor (12) that is disposed inside the stator core (11), spaced apart from the teeth portion (112), and uses a center axis of the yoke portion (111) as an axis of rotation (AR). The yoke portion (111) includes, on its outer circumferential surface, a notch portion (111a) at a position on the back side of the teeth portion (112). The notch portion (111a) has a circumferential width (W111a) smaller than a circumferential width (W112) of the teeth portion (112).