Single Phase Motor Stator Core with Closed Inner Ring
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Solution Overview
Problem
Conventional single phase permanent magnet motors experience high cogging torque and noise due to slot openings, leading to poor startup reliability and limited startup angles.
Innovation Solution
A single phase motor design featuring a stator core with a closed inner ring portion and magnetic bridges between teeth, along with positioning slots that are offset from the symmetrical center of adjacent teeth, creating a larger magnetic reluctance and allowing for adjustable startup angles and reduced cogging torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If slot openings are formed between pole shoes of adjacent teeth in a conventional single phase permanent magnet motor, then the motor structure is simplified and manufacturing is easier, but the motor generates unduly large cogging torque resulting in vibration and noise
Solution Approach 1:
The patent removes the harmful slot openings between pole shoes by forming a closed inner ring portion that connects adjacent pole shoes. This extraction of the problematic feature eliminates the source of cogging torque while maintaining manufacturing simplicity through the continuous structure.
Solution Approach 2:
Adjacent pole shoes are merged by forming a closed inner ring portion that connects them together. This merging eliminates the gaps between pole shoes, creating a continuous magnetic path that reduces cogging torque and vibration while simplifying the overall stator structure.
2Stability of the object's composition
If slot openings are formed between pole shoes of adjacent teeth, then the stator core can be formed as an integral structure, but the motor has a small startup angle and poor startup reliability
Solution Approach 1:
Magnetic bridges are introduced as intermediary elements between teeth, extending from the closed inner ring portion. These magnetic bridges act as mediators that provide controlled magnetic paths, enabling reliable startup by adjusting the startup angle while maintaining the integral structure benefits.
Solution Approach 2:
The patent introduces localized features (magnetic bridges and positioning slots) at specific locations between teeth, rather than changing the overall integral structure. This allows optimization of startup characteristics at critical locations while maintaining the manufacturing advantages of an integral stator core.
3Adaptability or versatility
If positioning slots are offset from the symmetrical center of adjacent teeth, then the startup angle can be adjusted for bidirectional startup, but the magnetic reluctance increases
Solution Approach 1:
Positioning slots are deliberately positioned asymmetrically, offset from the symmetrical center of adjacent teeth. This asymmetric positioning enables bidirectional startup capability by creating different magnetic reluctance paths for different rotation directions, allowing the motor to start in either direction from a standstill.
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 enhances startup reliability by allowing bidirectional startup and reducing vibration and noise, while increasing winding efficiency through a separate-type stator core structure.
Implementation Method 1
a magnetic bridge is disposed at a part of the inner ring portion between each two adjacent teeth
Implementation Method 2
the rotor comprises magnetic poles arranged along a circumferential direction of the rotor
Implementation Method 3
the magnetic poles of the rotor are formed by a plurality of permanent magnets
Data Source
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AI summary
A single phase permanent magnet motor (10) includes a stator (20) and a rotor (50). The stator (20) includes a stator core (30) and a stator winding (39). The stator core (30) includes an outer yoke (31), teeth (33) extending inwardly from the outer yoke (31), and pole shoes (35) extending from inner ends of the teeth (33). The rotor (50) is received in a space cooperatively defined by the pole shoes (35). The rotor (50) includes circumferentially arranged permanent magnetic poles (55). An outer circumferential surface of the permanent magnetic poles (55) is concentric with an inner circumferential surface of the pole shoes (35), such that a uniform air gap is formed between the pole shoes (35) and magnetic poles (55). The single phase permanent magnet motor (10) forms the uniform air gap, which reduces the vibration and noise. The pole shoes (35) form invisible positioning slots (38), which avoids the negative effect of the positioning slots (38)to the thickness of the air gap and reduces the startup dead point.