Electric Motor Rotor Axial Segmentation and Fastening
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Solution Overview
Problem
In electric motors, particularly those with brushless designs used in industrial and maritime applications, achieving high torque is challenging due to magnetic short-circuits in laminated cores, which lead to reduced torque, manufacturing tolerances issues, and potential damage to permanent magnets, resulting in noise and imbalance.
Innovation Solution
A rotor design featuring a rotor body composed of two sub-bodies joined axially with a clearance or press fit, using axles and sockets/lugs for precise alignment and force transfer, and incorporating permanent magnets within pockets to minimize magnetic interference and stabilize the assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If threaded rods are used to fasten laminated core, then high torque transmission is achieved, but manufacturing precision deteriorates due to alignment issues with permanent magnets
Solution Approach 1:
The rotor body is divided into multiple laminated cores that are stacked axially. Each lamination contains pockets for permanent magnets, and the threaded rod passes through all laminations to secure them together. This segmentation allows precise magnet placement in each lamination while maintaining high torque transmission through the stacked structure.
Solution Approach 2:
The threaded rod acts as an intermediary element that fastens multiple laminated cores together. By passing through recesses in each lamination, it secures the stacked structure without interfering with the permanent magnet placement in the pockets, thus resolving the conflict between torque transmission and manufacturing precision.
2Ease of manufacture
If larger manufacturing tolerances are selected to reduce costs, then assembly ease improves, but rotor stability deteriorates due to lamination misalignment
Solution Approach 1:
The rotor is constructed from multiple discrete laminated cores stacked axially. Each lamination can be manufactured independently with standard tolerances, and the threaded rod assembly secures them together. This segmentation allows flexible manufacturing tolerances while maintaining overall rotor stability through the stacked configuration.
Solution Approach 2:
The design anticipates manufacturing tolerances by using a stacked lamination structure with threaded fastening. This allows for positional variations in each lamination without compromising overall rotor stability, as the threaded rod secures all laminations together while the pockets maintain magnet alignment.
3Ease of manufacture
If threaded rods pass through entire laminated core, then assembly is simplified, but permanent magnets may be damaged during assembly
Solution Approach 1:
The permanent magnets are placed in pockets within each lamination before the threaded rod assembly. The threaded rod passes through recesses in the laminations, extracting the fastening function from the magnet placement process and preventing damage to the magnets during assembly.
Solution Approach 2:
The threaded rod serves as an intermediary fastening element that secures laminations through dedicated recesses, keeping the permanent magnets in their protected pockets. This separates the fastening function from the magnet placement, simplifying assembly while protecting magnet integrity.
4Ease of manufacture
If laminations are positioned at great distance from threaded rod to allow tolerance, then manufacturing cost reduces, but noise and imbalance increase due to lamination rotation
Solution Approach 1:
The rotor consists of multiple laminated cores stacked axially and secured by threaded rods. Each lamination is positioned with pockets for magnets, and the threaded rod passes through recesses in all laminations. This segmented stacked design allows cost-effective manufacturing with standard tolerances while preventing lamination rotation through secure fastening, eliminating noise and imbalance.
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 enhances torque transmission, reduces noise and imbalance, and simplifies assembly by allowing for tolerance compensation and precise magnet placement, while maintaining robustness and reducing manufacturing costs.
Implementation Method 1
permanent magnets arranged in pockets of a laminated core of the rotor... magnetic short-circuits result within the laminated core
Implementation Method 2
The electric motor is customarily energized by means of a converter... A field current may be injected into the brushless electric motor, which results in a formation of a reluctance torque
Implementation Method 3
threaded rods are ordinarily used for this purpose, which extend through the entire laminated core, and on the ends of which nuts are placed. The individual laminations are pressed against each other by tightening the nuts
Implementation Method 4
If comparatively large manufacturing tolerances are selected... it is possible to position the individual laminations at a comparatively great distance from the threaded rod
Data Source
AI summary
A rotor of an electric machine, in particular an electric motor, having a rotor body, which circumferentially surrounds a shaft and includes a first sub-body and a second sub-body. The first sub-body and the second sub-body are joined together in the axial direction by means of an axle which extends in the axial direction and is offset radially to the outside with respect to the shaft. The first sub-body includes an eyelet, within which a socket receiving the axle is arranged, and the second sub-body includes a lug, which receives the axle. An electric machine, in particular an electric motor, is also provided.