Outer Rotor Motor Stator Extended Portion Design
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Solution Overview
Problem
The driving efficiency of brushless DC motors used in electronic apparatuses, such as laser printers, is not effectively improved by forming extended portions on the stator's magnetic poles, as the increased distance between the magnet and the bent portion reduces magnetic flux flow and leads to magnetic saturation due to processing strains, resulting in iron loss and decreased efficiency.
Innovation Solution
The motor design includes a stator with plate-shaped members forming extended portions where the inner diameter of the bent portion closest to the magnet is smaller than the thickness of the plate-shaped member, reducing magnetic properties-deteriorated regions and increasing the effective area for magnetic flux flow, thus enhancing driving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the outer diameter of the bent portion is increased to provide extended portion, then the area for magnetic flux flow increases, but the distance between the bent portion and magnet increases reducing magnetic flux flow effect
Solution Approach 1:
The patent transitions from increasing area in the radial direction (outer diameter) to increasing area in the axial direction (length of extended portion). By bending the plate-shaped member axially parallel to the magnet's axis, the magnetic pole base area is extended without increasing the radial distance from the magnet, thus maintaining strong magnetic flux coupling while providing sufficient area for flux flow.
2Area of stationary object
If extended portion is formed by bending plate-shaped member, then magnetic pole base area is extended, but magnetic properties-deteriorated region is formed causing magnetic saturation
Solution Approach 1:
The patent changes the geometric parameters of the bent portion, specifically controlling the inner diameter to be smaller than the plate thickness. This parameter change optimizes the bending geometry to minimize the volume of the magnetic properties-deteriorated region, reducing magnetic saturation while maintaining the area extension benefit.
3Power
If extended portion is provided to increase driving force, then magnetic flux flow should increase, but processing strain causes magnetic saturation and iron loss
Solution Approach 1:
The patent optimizes the geometric parameters of the extended portion, specifically setting the inner diameter of the bent portion smaller than the plate thickness. This parameter optimization increases the effective magnetic pole base area for flux flow while minimizing the magnetic properties-deteriorated region, thereby increasing driving force while reducing iron loss from magnetic saturation.
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 increases the amount of magnetic flux flowing into the extended portion, reduces magnetic saturation, and minimizes iron loss, resulting in improved driving efficiency of the motor.
Implementation Method 1
the effect of causing magnetic fluxes from the magnet to flow thereinto
Implementation Method 2
a magnet magnetized to have opposite polarities at a second predetermined interval... magnetism-detecting element that magnetically detects rotation of the rotor
Data Source
AI summary
A stator 3 is provided with a plurality of magnetic poles 3a on the outer circumference thereof, and is configured from a plurality of layers of plate-shaped members. A rotor 4 is rotatably disposed around the stator. The inner circumferential face of the rotor is provided with a magnet 5. The outer circumferential ends of the magnetic poles of the stator are provided with an extended portion that is bent such that at least one plate-shaped member, including an outermost layer, of the plurality of plate-shaped members is substantially parallel to the magnet. When the inner diameter of a bent portion of a plate-shaped member that is the closest to the magnet of the at least one plate-shaped member constituting the extended portion is taken as R1i, and the thickness of the closest plate-shaped member is taken as T1, R1i<T1 is satisfied. Accordingly, it is possible to improve the driving efficiency of an outer rotor-type motor.