Electric Motor Rotor Deformation Prevention
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Solution Overview
Problem
Electric motor rotors face challenges with deformation and damage due to high temperatures and centrifugal forces, particularly when made of copper or aluminum, which also increase fabrication costs and reduce output density.
Innovation Solution
A rotor design featuring a rotor core with slots for conductor bars and end rings, where deformation preventing units with a lower thermal expansion coefficient than the end rings are used to restrict radial deformation, and protrusions and coupling portions facilitate secure attachment and heat dissipation, allowing for high-speed operation and improved output density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductor bars and end rings are made of copper, then electrical conductivity is improved, but fabrication cost increases due to material cost and machining requirements
Solution Approach 1:
The patent replaces expensive copper conductor bars and end rings with aluminum components, which are cheaper and easier to manufacture. The aluminum components are designed with sufficient electrical conductivity for the application, accepting that they may have shorter service life or require more frequent replacement compared to copper, thus resolving the contradiction between conductivity and fabrication cost.
Solution Approach 2:
The patent changes the material parameter from copper to aluminum, which has different electrical conductivity, thermal conductivity, and mechanical properties. This parameter change allows the use of cheaper materials while maintaining acceptable performance through design modifications such as increasing cross-sectional area or optimizing geometry.
2Ease of manufacture
If conductor bars and end rings are made of aluminum, then fabrication cost is reduced, but a relatively large sectional area is needed for sufficient electrical conductivity
Solution Approach 1:
The patent employs deformation preventing units that surround and constrain the aluminum end rings, creating a nested structure where the deformation preventing units enclose the conductor bars and end rings. This nesting allows the use of aluminum with larger sectional area while maintaining structural integrity and preventing deformation that would compromise electrical conductivity.
Solution Approach 2:
The patent applies deformation preventing units specifically at critical locations where aluminum components are most susceptible to deformation under centrifugal force and thermal stress. This localized quality enhancement allows the aluminum components to maintain their required sectional area for conductivity while preventing deformation in specific critical regions.
3Temperature
If ambient temperature increases during motor operation, then thermal deformation of the rotor occurs, but this causes interference with surrounding components
Solution Approach 1:
The patent incorporates deformation preventing units that are pre-installed on the rotor components before operation. These units provide preliminary constraint against thermal deformation, counteracting the expansive forces that occur when ambient temperature increases during motor operation, thus preventing interference with surrounding components.
Solution Approach 2:
The patent explicitly addresses thermal expansion by using deformation preventing units with different thermal expansion coefficients than the aluminum components they constrain. The deformation preventing units are designed to accommodate or counteract the thermal expansion of aluminum conductor bars and end rings, preventing excessive deformation that would cause interference with surrounding components.
4Productivity
If the rotor is operated at high speed, then output density is improved, but the rotor may be damaged by deformation due to high temperature and increase in centrifugal force
Solution Approach 1:
The patent employs deformation preventing units that are pre-installed to counteract centrifugal force and thermal stress before they cause damage. These units provide preliminary reinforcement to the rotor structure, allowing high-speed operation that improves output density while preventing rotor damage from deformation.
Solution Approach 2:
The deformation preventing units are designed with ring shapes that conform to the curved geometry of the rotor components. This curved design allows the deformation preventing units to effectively distribute and resist centrifugal forces acting on the aluminum conductor bars and end rings during high-speed rotation, maintaining structural integrity while enabling high output density.
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 design effectively prevents rotor deformation and damage, reduces fabrication costs, and enhances output density by using aluminum for conductor bars and end rings, while maintaining efficient heat dissipation and assembly.
Implementation Method 1
a thermal expansion coefficient of the deformation preventing units may be less than that of the end rings to restrict radial deformation of the end rings
Implementation Method 2
An electric motor is a device that can convert electric energy into mechanical energy
Data Source
AI summary
A rotor for an electric motor includes a rotor core defining a plurality of slots that are spaced apart from each other and arranged along a circumferential direction of the rotor core, and a rotor winding provided at the plurality of slots and configured to flow current. The rotor winding includes a plurality of conductor bars that extend in an axial direction of the rotor core and that are disposed in a slot of the plurality of slots, and end rings that are disposed at both sides of the plurality of conductor bars and that connect the plurality of conductor bars to each other. The rotor further includes deformation preventing units each of which surrounds and contacts an outer surface of one of the end rings. The deformation preventing units are configured to restrict deformation of the end rings.