Polygonal Motor Casing Vibration Reduction
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Solution Overview
Problem
Small motors with polygonal external shapes experience significant vibrations and noise due to flat wall portions, which are not adequately suppressed by existing press-fitting methods, particularly in applications requiring low noise and vibration levels like air conditioner dampers.
Innovation Solution
A small motor design featuring a polygonal external shape with a field magnet and motor casing where ribs are provided on the magnet's outer surface for press-fitting, allowing for adhesive bonding between the magnet and casing, thereby increasing vibration frequency and reducing amplitude, and shifting noise to less audible frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a polygonal external shape is used for the motor casing, then rotation prevention and space efficiency are improved, but vibration and noise increase due to flat wall portions
Solution Approach 1:
The invention introduces arcuate corner portions with curved surfaces at the corners of the polygonal motor casing. These curved portions replace the sharp angular corners and work in conjunction with rib structures to reduce vibration and noise while maintaining the overall polygonal shape for rotation prevention and space efficiency.
Solution Approach 2:
The motor casing is segmented into flat side portions and arcuate corner portions. This segmentation allows each portion to serve its specific function: flat portions provide structural integrity and polygonal shape, while arcuate corner portions reduce vibration and noise through their curved geometry.
2Object-generated harmful factors
If corner portions of the magnet are press-fitted to the motor casing, then vibration of flat wall portions is reduced, but magnetic field intensity at pole apexes decreases due to clearance requirements
Solution Approach 1:
The magnet is designed with different properties at different locations: corner portions have press-fitted structures for vibration reduction, while pole apex portions maintain clearances to preserve magnetic field intensity. This local differentiation allows each region to optimize its function without compromising the other.
Solution Approach 2:
The magnet is segmented into corner portions and pole portions with different structural characteristics. Corner portions are designed for press-fitting to reduce vibration, while pole portions are designed with clearances to maintain magnetic field strength, resolving the contradiction between vibration reduction and magnetic performance.
3Ease of manufacture
If the entire outer circumferential surface of the magnet uniformly contacts the motor casing, then manufacturing simplicity is improved, but corner portions cannot be effectively press-fitted for vibration reduction
Solution Approach 1:
The contact surface between magnet and motor casing is segmented into corner contact regions and side contact regions. This segmentation enables effective press-fitting at corner portions for vibration reduction while maintaining manufacturability through defined contact zones rather than requiring uniform contact across the entire surface.
Solution Approach 2:
Different contact characteristics are applied locally: corner portions have press-fitted contact for vibration reduction, while side portions have controlled contact for manufacturability. This local differentiation resolves the contradiction between manufacturing simplicity and vibration reduction effectiveness.
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 motor achieves a 50% reduction in vibration amplitude and an 11% increase in vibration frequency, moving noise to a less audible range, while maintaining efficient magnetic flux and cost-effective production.
Implementation Method 1
The small motor according to the present invention employs a structure in which a rib 41 comes into contact with the inner circumferential surface 32 of the motor casing 3 through press-fitting
Implementation Method 2
allowing for adhesive bonding between the magnet and casing, thereby increasing vibration frequency and reducing amplitude
Implementation Method 3
maintaining efficient magnetic flux
Data Source
Figure 1~2
Figure 3(A)~4
Figure 5
AI summary
A side wall of a motor casing is formed into a polygonal shape such that flat side portions and corner portions located at respective corners between the side portions are continuously joined together. A field magnet, which has an outer circumferential shape approximately coinciding with the inner circumferential shape of the motor casing, has magnet side portions and magnet corner portions, and has a rib provided on outer circumferential surfaces of the magnet side portions. The magnet is disposed, through press-fitting, within the motor casing such that at least the rib comes into contact with the inner circumferential surface of the motor casing, wherein the magnet side portions, excluding the rib, are formed such that small clearances are formed between the magnet side portions and the side portions of the motor casing, or at least such that no pressing force acts on the magnet side portions, excluding the rib.