Polygon Housing Electric Motor with Variable Magnet Thickness
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Solution Overview
Problem
Conventional electric motors with permanent magnet stators face challenges such as rolling during transportation due to cylindrical housings and low space utilization rates, especially in small motors with square housings.
Innovation Solution
A stator with a polygonal housing featuring a ring magnet, where the ring magnet's thickness varies to match corner and side portions, creating an uneven air gap and gaps between the magnet and housing for improved installation and space efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a square motor housing is used, then the motor does not roll during transportation and installation is improved, but the space utilization rate becomes low
Solution Approach 1:
The ring magnet is designed with non-uniform thickness, where the thickness at corner portions is greater than at side portions. This local variation in magnet thickness optimizes the magnetic field distribution in different regions, improving space utilization while maintaining the square housing configuration for stable installation.
Solution Approach 2:
The air gap is designed to be non-uniform, with smaller thickness at corner portions and larger thickness at side portions. This asymmetric air gap design, combined with the varying magnet thickness, maximizes the use of available space in the square housing while ensuring proper magnetic coupling between the rotor and stator.
2Power
If the rotor outer diameter is increased, then the motor power is improved, but the motor size and housing dimensions must be increased
Solution Approach 1:
By varying the ring magnet thickness locally (thicker at corners, thinner at sides), the magnetic field strength is optimized in different regions. This allows achieving higher motor power with a smaller rotor diameter, as the concentrated magnetic flux at corner portions provides stronger torque generation without increasing the overall rotor size.
Solution Approach 2:
The air gap thickness is changed as a parameter, being smaller at corner portions and larger at side portions. This parameter variation allows the motor to achieve higher power density by optimizing the magnetic coupling efficiency, enabling increased motor power without proportionally increasing the housing dimensions.
3Ease of manufacture
If uniform thickness ring magnet is used, then manufacturing is simplified, but the magnetic field distribution is suboptimal
Solution Approach 1:
The ring magnet is designed with different thicknesses at different locations (thicker at corners, thinner at sides) to create optimized magnetic field distribution. This local quality variation ensures stronger magnetic coupling where needed while maintaining manufacturability through a relatively simple radial extrusion process.
Solution Approach 2:
The magnet thickness parameter is varied radially around the ring magnet to optimize magnetic field distribution. By changing the thickness parameter at different angular positions, the design achieves improved magnetic coupling and field uniformity while keeping the manufacturing process practical and cost-effective.
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 solution enhances space utilization and reduces the risk of demagnetization while facilitating easier installation by optimizing the air gap and magnet placement, leading to improved motor performance and stability.
Implementation Method 1
permanent magnets 2 fixed at inner surface of the cylindrical housing
Implementation Method 2
an air gap being formed between a peripheral surface of the rotor and an inner surface of the ring magnet
Data Source
AI summary
An electric motor has a rotor (20), a housing (10) and a ring magnet (12) fixed onto an inner surface of the housing. The housing (10) has a cross section in a polygon, preferably tetragonal, shape that comprises a plurality of side portions (10a˜10d) and a plurality of curved corner portions (11a˜11d), each of which connects two adjacent side portions. The thickness of the ring magnet at portions corresponding to the corner portions of the housing is larger than the thickness of the ring magnet at portions corresponding to the side portions of the housing. An air gap (123) is formed between a peripheral surface of the rotor and an inner surface of the ring magnet, the thickness of the air gap at portions corresponding to the corner portions of the housing being smaller than that of the air gap at portions corresponding to the side portions of the housing. The motor has a polygon housing which is convenient to install and has good space utilization.