Electric Motor Rotor Casting Through Perforated Discs
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Solution Overview
Problem
Existing methods for producing rotors for electric motors with laminated cores and magnets result in large magnet pockets, which reduce torque density due to the need for large cross-sectional overlaps and skewing angles.
Innovation Solution
A method involving the creation of a continuous axial passage through laminated cores using perforated disks with openings that connect adjacent magnet pockets, allowing a casting compound to flow from one end face to the other, thereby fixing the rotor and magnets while minimizing magnet pocket size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large cross-sectional overlaps of magnet pockets are used to allow casting compound to flow through the rotor, then the casting compound can properly fix the magnets and laminated cores, but the magnet pocket size increases which reduces torque density
Solution Approach 1:
The rotor is divided into multiple individual laminated cores (stacks) that are twisted relative to each other. Instead of requiring the casting compound to flow through the entire rotor length in a single continuous path, the segmentation allows each laminated core to be fixed independently, reducing the required overlap area and magnet pocket size while maintaining reliable fixation.
Solution Approach 2:
Perforated disks are introduced as intermediary components between adjacent laminated cores. These disks provide structural support and facilitate the casting compound flow path, enabling effective fixation of each laminated core segment without requiring large cross-sectional overlaps between magnet pockets.
2Reliability
If large magnet pockets are created to accommodate the casting compound flow path, then the rotor can be properly fixed, but the torque density of the electric motor decreases
Solution Approach 1:
By segmenting the rotor into multiple laminated cores with smaller individual magnet pockets, the casting compound only needs to fill small gaps between magnets and laminated core surfaces in each segment, rather than flowing through large magnet pockets. This segmentation enables reliable fixation while preserving torque density.
Solution Approach 2:
The invention transitions from a single continuous casting path in the axial direction to multiple localized filling paths that combine axial and radial components. The casting compound is injected radially into each magnet pocket and then flows axially through the small gaps, utilizing both dimensional directions to achieve fixation without enlarging magnet pockets.
3Reliability
If the casting compound flows through the entire rotor length, then all magnets and laminated cores are fixed, but the required overlap area increases which is undesirable
Solution Approach 1:
The rotor is segmented into multiple laminated cores that can be fixed independently. The casting compound flows through each segment separately rather than requiring a single continuous path through the entire rotor length, eliminating the need for large cross-sectional overlaps while achieving comprehensive fixation of all components.
Solution Approach 2:
Instead of requiring the casting compound to flow through the entire rotor length with large overlaps, the invention applies partial action by filling only the small gaps between magnets and laminated core surfaces in each segment. This partial filling approach is sufficient for fixation and eliminates the excessive overlap area requirement.
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 enables the production of rotors with high torque density and improved thermal connection between magnets and the laminated core, while maintaining reliable fixation of the laminated cores.
Implementation Method 1
a casting compound, for example an epoxy resin, wherein the casting compound flows through the opening and is preferably pressed from one end face through the magnet pockets or the opening(s) of the perforated disc(s) to the other end face of the rotor
Implementation Method 2
Epoxy resin is a good heat exchanger and at the same time electrically insulating
Implementation Method 3
Epoxy resin is a good heat exchanger and at the same time electrically insulating
Data Source
AI summary
The present invention relates to a method for producing a rotor (1) of an electric motor (2) with laminated cores (4) arranged on a rotor shaft (3), in which—at least two laminated cores (4) twisted relative to one another in the circumferential direction (5) with magnet pockets (6) and magnets (7) arranged therein are arranged on the rotor shaft (3),—in the axial direction (8) between two laminated cores (4) at least one perforated disc (9) with at least one opening (10) is arranged such that the opening (10) overlaps and connects two magnet pockets (6) of two laminated cores (4) adjacent to the perforated disc (9),—a gap between the magnet pockets (6) and the magnets (7) is filled by means of a hardening casting compound (11) wherein the casting compound (10) flows through the opening (10).