Resin-Fiber Composite Rotor Bell for External-Rotor Machines
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Solution Overview
Problem
Existing permanent-magnet-excited electric external rotor machines face challenges in achieving high power density and cost-effective manufacturing with materials like aluminum, which are limited by thermal expansion coefficients and cost constraints, and require complex post-processing for precise air gaps to maintain efficiency and stability.
Innovation Solution
A rotor design using multiple layers of resin fiber composite material with strategically angled filament bundles and integrated permanent magnet elements, allowing for high rigidity and efficient series production, with the filament bundles being wound around a mandrel to form a single, integral rotor bell that reduces manufacturing complexity and waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If aluminum is used for the rotor base, then cost is reduced and inertia is lowered, but thermal expansion coefficient mismatch with composite material causes manufacturing precision issues
Solution Approach 1:
The patent changes the material parameter from aluminum to glass fiber reinforced plastic for the rotor base, which has a thermal expansion coefficient closely matching the composite rotor tube material, thereby eliminating thermal expansion mismatch issues while maintaining cost-effectiveness through integrated molding
Solution Approach 2:
The patent uses glass fiber reinforced plastic as a composite material for the rotor base, which provides both mechanical strength and thermal expansion compatibility with the rotor tube, resolving the contradiction between cost and manufacturing precision
2Manufacturing precision
If titanium is used for the rotor base, then thermal expansion coefficient mismatch is reduced and structural integrity is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent changes the material parameter from titanium to glass fiber reinforced plastic, achieving similar thermal expansion compatibility at a fraction of the cost, making the solution economically viable for mass production
Solution Approach 2:
The patent replaces expensive titanium with a more economical composite material that achieves the same functional requirements, demonstrating the principle of using cheaper materials when they can meet the performance requirements
3Manufacturing precision
If complex post-processing is applied to achieve precise air gaps, then manufacturing precision is improved, but productivity is reduced and manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary action by designing the rotor base and rotor tube as an integrated molded component with pre-established precise geometry, eliminating the need for subsequent post-processing operations to achieve air gap precision
Solution Approach 2:
The patent merges the rotor base and rotor tube into a single integrated component through injection molding, combining multiple manufacturing steps into one process, thereby improving productivity while maintaining precision
4Ease of manufacture
If separate manufacturing of rotor base and rotor tube is performed, then ease of manufacture is improved, but device complexity and post-processing requirements increase
Solution Approach 1:
The patent merges the rotor base and rotor tube manufacturing into a single injection molding process, creating an integrated component that reduces assembly complexity and eliminates post-processing operations while maintaining manufacturing flexibility
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 approach results in a highly efficient, compact, and cost-effective permanent-magnet electric machine with improved mechanical stability, reduced weight, and precise air gaps, enhancing magnetic excitation and minimizing material usage while eliminating the need for complex post-processing.
Implementation Method 1
A rotor (14) for such an electrical machine and a method for producing same The rotor (14) has a rotor bell (20) which has multiple layers of resin fiber composite
Implementation Method 2
A permanent magnet excited electrical external rotor machine is described below. In particular, it is a transverse flux machine with a stator and a rotor, the stator having a stator coil and the rotor being provided with permanent magnet elements
Implementation Method 3
The rotor bell carries permanent magnet elements which are embedded in the fiber composite material
Data Source
Figure 1
Figure 2~3
Figure 3a
AI summary
Permanent-magnet electric machine comprising a stator and a rotor, wherein the stator has a coil arrangement and the rotor is provided with permanent magnet elements, an air gap is formed between the stator and the rotor, which air gap is delimited by the permanent magnet elements and with magnetically conductive teeth of the stator which are aligned in specific positions with said permanent magnet elements, wherein the rotor has a rotor bell, which has a plurality of layers of resin-fibre composite material, is an integral body having a rotor tube and a rotor base and has at least one filament bundle in the region of the rotor base, wherein the at least one filament bundle reaches from the centre of the rotor base substantially along imaginary radii or secants over the outer rim of the rotor base and is bent back at the outer rim of the rotor base and merges, uninterrupted, with the rotor tube in the axial direction and/or at an angle with respect to the mid-longitudinal axis of the rotor tube up to the free peripheral region thereof.