Electric Motor Rotor Axial Protrusion Design for Torque Enhancement
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Solution Overview
Problem
Conventional electric motors face challenges in achieving high output while maintaining a compact size, particularly in applications like in-wheel driving motors for electric vehicles and washing machines, where increased magnetic field intensity and conductive wire length lead to larger motor sizes and limited driving voltage due to counter-electromotive force.
Innovation Solution
The rotor design includes protrusion portions and concave portions with permanent magnets and pole pieces, where the pole pieces are shorter than the protrusion portions in the axial direction, and a reinforcing member made of ferromagnetic material is used to enhance magnetic flux, along with a blocking member of magnetically non-permeable material to prevent leakage flux, optimizing magnetic path and torque generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the intensity of the magnetic field and the length of the conductive wire are increased to achieve high output, then the output increases, but the size of the electric motor increases
Solution Approach 1:
The invention utilizes the axial dimension by extending protrusion portions beyond the pole pieces in the axial direction. This allows the magnetic path to extend axially rather than only radially, enabling increased magnetic flux and output without proportionally increasing the radial or axial dimensions of the motor, thus resolving the contradiction between high output and compact size.
Solution Approach 2:
The invention changes the geometric parameters of the rotor structure by creating protrusion portions that extend axially beyond the pole pieces. This parameter change optimizes the magnetic path length and cross-sectional area, increasing magnetic flux density and reducing counter-electromotive force, thereby achieving higher output in a compact configuration.
2Power
If the intensity of the magnetic field is increased to achieve high output, then the output increases, but the counter-electromotive force increases limiting driving voltage
Solution Approach 1:
The invention optimizes magnetic flux density distribution by extending protrusion portions axially beyond pole pieces. This geometric parameter change increases the effective magnetic path area, allowing higher magnetic flux for the same magnet strength, thereby increasing output while the optimized flux distribution reduces counter-electromotive force.
Solution Approach 2:
By extending the magnetic path in the axial direction through protrusion portions, the invention creates additional magnetic flux pathways that increase overall magnetic flux without proportionally increasing counter-electromotive force, as the extended axial portion provides increased magnetic coupling area that reduces back-EMF.
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 design increases torque and reduces counter-electromotive force, resulting in a higher output and more efficient driving voltage, with a torque enhancement of about 4.5% compared to traditional overhang structures, and improved magnetic reluctance reduction.
Implementation Method 1
a rotor that rotates with respect to a stator according to an electromagnetic interaction with the stator
Implementation Method 2
a plurality of permanent magnets which are respectively disposed at the plurality of concave portions
Implementation Method 3
a reinforcing member which includes a plurality of reinforcing parts respectively corresponding to the plurality of protrusion portions, wherein the reinforcing member is formed of a ferromagnetic material
Implementation Method 4
a blocking member which is formed of a magnetically non-permeable material, and is disposed on at least one of an upper side and lower side of each of the pole pieces of the respective concave portions, wherein the blocking member is configured to prevent a leakage magnetic flux between adjacent pole pieces
Data Source
AI summary
Exemplary embodiments disclose a rotor of an electric motor and an electric motor using the same. The rotor includes a core which includes a plurality of protrusion portions which are arranged along an outer circumference of the core and protrude radially to an outer portion of the core, and a plurality of concave portions interposed between the protrusion portions; a plurality of permanent magnets which are respectively disposed at the plurality of concave portions; and a plurality of pole pieces which are disposed at the plurality of concave portions and at outer sides of the plurality of permanent magnets. A length of each of the plurality of pole pieces in an axial direction is shorter than a length of each of the plurality of protrusion portions in the axial direction.