Consequent Pole Rotor Structure for Lower-Mass Power Tool Motors
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Solution Overview
Problem
Existing power tool motors face challenges in achieving efficient performance and reduced mass while maintaining torque and speed capabilities, particularly in designs that incorporate internal permanent magnet motors.
Innovation Solution
The implementation of a consequent pole motor design featuring a rotor with a lamination stack, rare earth permanent magnets, and non-magnetic consequent poles, along with injection molded air gaps and axial support structures, which allows for a reduced mass without compromising performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If traditional internal permanent magnet motor design is used, then torque and speed capabilities are maintained, but mass is higher
Solution Approach 1:
The patent removes the magnetic material from the rotor core, extracting only the permanent magnets and consequent poles while eliminating the heavy ferromagnetic rotor body. This extraction achieves mass reduction while maintaining torque capability through the retained permanent magnets and consequent pole structure.
Solution Approach 2:
The patent employs composite material construction by combining non-magnetic rotor core material with rare earth permanent magnets and consequent poles. This composite approach allows the rotor to maintain magnetic field generation capability through the permanent magnets while the non-magnetic core reduces overall mass compared to traditional ferromagnetic rotors.
2Weight of moving object
If consequent pole design with non-magnetic material is used, then mass is reduced, but manufacturing complexity increases
Solution Approach 1:
The rotor is segmented into distinct functional components: non-magnetic core structure, permanent magnets, and consequent poles. This segmentation allows each component to be manufactured separately using optimized processes and then assembled, reducing overall manufacturing complexity despite the advanced design.
Solution Approach 2:
The consequent poles are nested within the rotor structure between the permanent magnets and the rotor core. This nesting arrangement consolidates multiple functional elements into a compact configuration, simplifying the overall manufacturing process by reducing the number of separate assembly operations required.
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 achieves a significant mass reduction of up to 36% compared to traditional internal permanent magnet motors while maintaining similar performance within target operating regions, indicating improved efficiency and power output.
Implementation Method 1
a motor including: a stator including a plurality of stator teeth configured to receive a plurality of stator windings, and a rotor configured to rotate with respect to the stator. The rotor includes a first permanent magnet within the rotor, a second permanent magnet within the rotor
Implementation Method 2
a consequent pole located between the first permanent magnet and the second permanent magnet. The consequent pole has a length and a width. The consequent pole is made of a non-magnetic material
Data Source
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AI summary
A power tool including a battery pack interface and a consequent pole motor. The battery pack interface is configured to receive a removable and rechargeable battery pack. The consequent pole motor includes a stator including a plurality of stator teeth configured to receive a plurality of stator coils, and a rotor configured to rotate with respect to the stator. The rotor includes a first permanent magnet positioned within the rotor, a second permanent magnet positioned within the rotor, and a consequent pole located between the first permanent magnet and the second permanent magnet. The consequent pole has a length and a width. The consequent pole is made of a non-magnetic material.