Bi-Pole Multi-Rotor Torque Phasing for Smoother Gear Loads
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Solution Overview
Problem
Multi-rotor electric machines suffer from unsteady output torque characteristics and low durability due to variability in torque at the rotor level, requiring complex configurations and high-strength, expensive gears that are prone to fretting damage.
Innovation Solution
The electric machine system comprises multiple rotors with phased indexing and gear configurations, where each rotor is connected via shafts with parallel rotation axes, providing torque phase offsets between machines to reduce torque ripple and distribute stress, thereby enhancing durability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple rotors are used to enhance power output, then power capability is improved, but torque ripple and variability increase causing unsteady output torque characteristics
Solution Approach 1:
The system divides the power generation function across multiple independent rotors (first rotor, second rotor, third rotor), each connected to the load through separate shafts and gears. This segmentation allows individual torque variations to be distributed and averaged out, reducing overall torque ripple while maintaining high power output capability.
Solution Approach 2:
The patent combines multiple rotor systems with parallel shafts and gear trains into a unified power transmission architecture. By merging the output of multiple rotors through a common load connection, the system achieves smooth continuous torque delivery as the variations from individual rotors complement rather than compound each other.
2Power
If complex configurations are used to achieve multiple rotor integration, then power capability is improved, but device complexity increases
Solution Approach 1:
The system segments the multi-rotor configuration into independent modular units, each consisting of a rotor-shaft-gear assembly. This modular segmentation simplifies the overall design by allowing each unit to be designed, manufactured, and maintained independently, reducing the complexity burden of integrating multiple rotors.
Solution Approach 2:
The patent arranges multiple rotors and shafts in parallel spatial dimensions rather than sequential arrangements. This dimensional reorganization allows multiple power sources to operate simultaneously without requiring complex transmission pathways, simplifying the overall system architecture while maintaining high power output.
3Reliability
If high-strength gears are used to handle torque variability, then durability is improved, but cost increases and fretting damage risk remains
Solution Approach 1:
The system provides beforehand cushioning by distributing torque variability across multiple rotors before it reaches the gears. This pre-distribution of torque stresses prevents peak loads from concentrating on individual gear sets, allowing the use of less expensive, lower-strength gear materials while maintaining durability and reducing fretting damage risk.
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 system achieves reduced torque ripple and cyclic stress on gears, increasing the working life of components and allowing for the use of less expensive materials, while maintaining smooth and continuous torque delivery.
Implementation Method 1
Electric machines with multiple rotors are known and may provide enhanced power over conventional electric machines
Data Source
AI summary
An electric machine system disclosed herein comprises first and second electric machines configured to drive a load. The first electric machine has a plurality of first rotors. The second electric machine has a plurality of second rotors. At least one of the second rotors is indexed relative to a respective one of the first rotors to, in use, provide a torque phase offset between the first and second electric machines. A shaft is coupled to the load and connects the respective one of the first rotors with the at least one of the second rotors. The respective one of the first rotors is coaxial with and axially spaced apart from the at least one of the second rotors.