Counterrotating Electric Machine with Nested Rotor Design
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Solution Overview
Problem
Existing counterrotating electric machines for vehicles, such as helicopters, face challenges with increased weight and inefficient rotational speed when using separate electric machines for each rotor, which can impact performance and efficiency.
Innovation Solution
A counterrotating electric machine design featuring a first rotor with magnets and a second rotor with windings, aligned along an axis, where the magnets of the first rotor are positioned inward of the windings of the second rotor, and both are mechanically coupled, allowing for efficient mechanical coupling and power transfer between the rotors, along with a casing and differential bearings for support and airflow features for cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If two separate electric machines are used to drive counterrotating rotors, then each rotor can be driven independently, but the weight of the electric machine system increases
Solution Approach 1:
The patent combines two separate electric machines into a single integrated electric machine with two rotors sharing a common stator. The first rotor has magnets and the second rotor has windings, both interacting with the same stator magnetic field. This merging reduces the overall weight by eliminating duplicate stator components while maintaining independent control capability through the differential bearing assembly that allows the rotors to rotate in opposite directions at different speeds.
Solution Approach 2:
The patent implements a nested configuration where the second rotor is positioned within the magnetic field generated by the first rotor and the stator. The rotors are arranged concentrically with the first rotor having magnets positioned inward of the windings of the second rotor along the radial direction. This nested arrangement allows both rotors to occupy the same spatial envelope, reducing overall system size and weight while enabling independent operation through electromagnetic interaction.
2Ease of operation
If two separate electric machines are used to drive counterrotating rotors, then each rotor can be driven independently, but the rotational speed efficiency decreases
Solution Approach 1:
The integrated electric machine design allows both rotors to benefit from a shared stator and magnetic field system, improving rotational speed efficiency. The first rotor with magnets generates a magnetic field that interacts with the windings of the second rotor, creating a coupled electromagnetic system that can transfer energy more efficiently than two separate machines while maintaining independent speed control through the differential bearing assembly.
Solution Approach 2:
The patent introduces a differential bearing assembly as an intermediary mechanism between the two rotors. This bearing assembly enables the rotors to rotate in opposite directions at different speeds while maintaining mechanical coupling. The differential bearing acts as a mediator that allows independent rotational control of each rotor while sharing the electromagnetic field infrastructure, thereby improving overall system efficiency.
3Weight of moving object
If magnets and windings are aligned along the axis with magnets positioned inward, then weight is reduced and space is optimized, but manufacturing complexity increases
Solution Approach 1:
The patent positions the magnets of the first rotor inward of the windings of the second rotor along the radial direction, creating a nested configuration. This arrangement reduces the overall radial dimension of the electric machine, minimizing the space required and reducing weight by eliminating redundant structural components. The nested design allows both rotor elements to occupy concentric zones within the same stator envelope.
Solution Approach 2:
The patent applies local quality by differentiating the radial positions of magnets and windings within the rotor assembly. The magnets are positioned in an inner radial zone while the windings occupy an outer radial zone, allowing each component to be optimized for its specific location. This localized arrangement reduces overall machine dimensions and weight while the modular rotor design helps manage manufacturing complexity through standardized component interfaces.
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 enables efficient power transfer and reduced weight, achieving the desired rotational speed and efficiency for counterrotating components, such as helicopter rotors, by optimizing the integration of electric machines within the drive system.
Implementation Method 1
the plurality of magnets of the first EM rotor operably engaged with the plurality of windings of the second EM rotor
Data Source
AI summary
An electric machine for a drive system having a first DS rotor and a second DS rotor includes a first EM rotor rotatable about an axis in a first circumferential direction and including a plurality of magnets, the first EM rotor configured for mechanical coupling to the first DS rotor; and a second EM rotor rotatable about the axis in a second circumferential direction and including a plurality of windings, the second EM rotor configured for mechanical coupling to the second DS rotor and the plurality of magnets of the first EM rotor operably engaged with the plurality of windings of the second EM rotor.