Rotor Magnet Hole Injection Design for Core Strength
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Solution Overview
Problem
Existing rotor designs face issues with strength deterioration, magnetic characteristic influence, and downsizing limitations due to resin injection methods, as well as excessive surface pressure and stress distribution problems.
Innovation Solution
A rotor design featuring a rotor core with hole portions arranged circumferentially, where a filling portion is injected from the central part of the magnet to secure it radially, eliminating the need for additional injection holes and incorporating extensions to aid resin spread, and a laminated steel end plate with projections to avoid excessive surface pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate hole is provided for injecting resin, then the magnet can be secured to the rotor core, but the strength of the rotor core deteriorates and downsizing is hindered
Solution Approach 1:
The patent merges the magnet insertion hole and the resin injection function into a single hole. The resin is injected through the same hole used for magnet insertion, eliminating the need for a separate injection hole. This resolves the contradiction by maintaining magnet securing reliability while preserving rotor core strength and enabling downsizing.
Solution Approach 2:
The hole in the rotor core serves multiple functions: it acts as both the magnet insertion channel and the resin injection pathway. This multi-functionality eliminates the need for additional holes, thereby maintaining structural integrity and enabling compact design while ensuring reliable magnet fixation.
2Volume of moving object
If the filling portion is injected from the opening of the hole portion, then the rotor can be downsized and strength deterioration is suppressed, but the magnet may not be evenly pressed in the radial direction
Solution Approach 1:
The patent applies local quality by positioning the filling portion injection at a specific location (central part in width direction) and designing the hole portion with localized extensions at corner portions. This targeted approach ensures both compact size and precise magnet pressing by controlling resin flow patterns in critical areas.
Solution Approach 2:
The hole portion includes extensions at the corner portions that protrude toward the magnet corners. These extensions are designed in advance to guide and evenly distribute the resin flow, ensuring uniform magnet pressing in the radial direction before the magnet is fully secured, thereby achieving both downsizing and high precision.
3Ease of manufacture
If a groove is provided in the end plate to avoid caulked portion, then the laminated steel interference is avoided, but the surface pressure between rotor core and end plate becomes excessively increased
Solution Approach 1:
The patent segments the end plate into multiple regions by providing grooves that divide the contact surface. This segmentation allows the end plate to accommodate the caulked portion while distributing the surface pressure across multiple areas, preventing excessive pressure concentration and enabling feasible assembly.
Data Source
AI summary
A rotor includes a rotor core fixedly attached to a rotational shaft and having a plurality of hole portions arranged in the circumferential direction, a magnet inserted into a plurality of hole portions each, and a filling portion injected into the hole portion. The filling portion is injected into the hole portion from a gate facing a central part in the width direction of the magnet in the opening of the hole portion.