Electric Drive Motor Noise Reduction via Air Gap Indentations
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Solution Overview
Problem
Electric drive motors, particularly BLDC motors used in household appliances, face challenges in reducing noise and torque fluctuations due to harmonics, which are often associated with reduced power density and increased noise levels, and existing solutions either compromise on noise or power efficiency.
Innovation Solution
The electric drive motor features a stator and permanent magnet rotor with equally spaced v locking positions realized by spherical or conical indentations in the air gap, optimizing the air gap width and using a laminated core with radially embedded permanent magnets to minimize cogging torque and harmonics, while maintaining high magnetic flux and power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the air gap is widened to reduce torque fluctuations and noise, then noise levels are reduced, but power density is reduced
Solution Approach 1:
The patent applies local quality by creating detent positions at specific locations in the air gap rather than uniformly modifying the entire air gap. The detent positions are localized spherical or conical indentations on the stator and/or rotor surfaces, concentrating the noise reduction effect at specific angular positions while preserving the overall air gap dimensions for power density.
Solution Approach 2:
The patent transitions from modifying the air gap width (one-dimensional approach) to modifying the air gap surface geometry (two-dimensional approach). By creating detent positions through spherical or conical indentations on the air gap surfaces, the solution adds a radial dimension to the air gap structure, allowing noise reduction without compromising the axial air gap width that determines power density.
2Object-affected harmful factors
If detent positions are added to reduce harmonics and noise, then noise excitations are reduced, but device complexity increases
Solution Approach 1:
The patent employs spheroidality by using spherical or conical indentations to create detent positions. These curved geometric features are simpler to manufacture than complex mechanical structures, as they can be created through standard machining or molding processes. The spherical/conical shape provides the necessary magnetic detent effect while maintaining manufacturing simplicity.
Solution Approach 2:
The patent applies parameter changes by modifying the geometric parameters of the air gap surfaces (creating spherical or conical indentations) rather than adding entirely new components. This approach changes the physical parameters of existing structures (stator and/or rotor surfaces) to achieve the desired harmonic reduction, avoiding increased device complexity.
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 configuration effectively reduces specific harmonics and noise excitations, allowing for efficient operation with reduced noise and torque fluctuations without compromising power utilization or increasing other orders, thus enhancing the motor's performance and efficiency.
Implementation Method 1
The stator and permanent magnet rotor each have, on their surfaces facing the air gap, equally spaced v locking positions... The permanent magnets are arranged in the through-holes such that a magnetic flux emanating from each permanent magnet is tangential to the rotor
Implementation Method 2
a segment of the rotor assembly is formed between adjacent through-holes which is designed to concentrate the magnetic flux of the respective permanent magnets in an air gap of the electric machine
Implementation Method 3
The occurrence of noise during the operation of an electric drive motor can either be prevented or at least reduced by appropriately influencing either the cause or the propagation path. One cause of noise is torque fluctuations. Generally, torque fluctuations in an electric drive motor can be reduced by widening or at least appropriately designing the air gap
Data Source
Figure 1~2b
Figure 3~4c
Figure 5~6
AI summary
The invention relates to an electric drive motor 1 comprising a stator 2 and a permanent magnet rotor 3, which has a motor shaft 4 and a laminated core 5 mounted on the motor shaft 4, wherein the stator 2 and the permanent magnet rotor 3 are separated from each other by an air gap 6, and wherein the stator 2 and the permanent magnet rotor 3 each have equally spaced detent positions 9 on their surfaces 7, 8 facing the air gap 6, which are each realized by protrusions or depressions 10 in the surfaces 7, 8. The invention also relates to a household appliance containing this electric drive motor 1 and to methods for its design and operation.