IPM Rotor Resin Layout for Permanent Magnet Fixing Stability
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Solution Overview
Problem
Existing IPM rotors for rotating electric machines face issues with peeling and breakage of fixing resin due to thermal stress, vibration, and centrifugal force, leading to instability of permanent magnets in magnet-receiving holes.
Innovation Solution
The rotor design incorporates a fixing resin with different adhesive strengths for the radially outer and inner sides of the magnet-receiving holes, with the radially outer resin having a higher adhesive strength than the inner resin, ensuring that peeling and breakage occur preferentially on the inner side, maintaining the fixed state of the permanent magnets on the outer side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform fixing resin is used on both radially outer and inner wall surfaces, then manufacturing process is simple, but peeling and breakage occur under thermal stress and centrifugal force leading to magnet instability
Solution Approach 1:
The patent applies different adhesive strengths of fixing resin to different locations (radially outer vs radially inner wall surfaces) based on the local stress conditions. The radially outer surface experiences higher centrifugal force and thermal stress, so it receives resin with higher adhesive strength, while the radially inner surface receives resin with lower adhesive strength. This local differentiation resolves the contradiction by improving reliability where needed without uniformly increasing complexity throughout the entire structure.
Solution Approach 2:
The fixing resin is segmented into at least two different types with different adhesive strengths, applied to different portions of the magnet-receiving hole. This segmentation allows the system to address the specific mechanical stresses acting on different surfaces independently, preventing peeling and breakage on the critical radially outer surface while maintaining manufacturing feasibility.
2Strength
If high adhesive strength resin is applied to both surfaces, then magnet fixation is strong, but manufacturing cost increases and resin usage increases
Solution Approach 1:
Instead of applying high adhesive strength resin uniformly to all surfaces, the patent applies high adhesive strength resin only to the radially outer wall surface where the stress concentration and peeling risk are highest. The radially inner wall surface uses resin with lower adhesive strength. This local quality approach ensures adequate fixation strength where needed while reducing the total quantity of high-performance resin required, thereby lowering manufacturing costs.
Solution Approach 2:
The patent acknowledges that not all surfaces require equal adhesive strength. By intentionally using lower adhesive strength resin on the radially inner surface where stress is lower, the system optimizes resin usage and reduces cost, while the critical outer surface receives the enhanced adhesive strength needed to prevent peeling and breakage under centrifugal force and thermal stress.
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 configuration enhances the stability of permanent magnets in the rotor core by minimizing resin usage and reducing manufacturing costs while maintaining the fixed state under thermal and mechanical stresses, thereby improving the rotor's operational reliability.
Implementation Method 1
Each of the permanent magnets is fixed in a corresponding magnet-receiving hole by a fixing resin that includes a radially outer resin interposed between the permanent magnet and the radially-outer wall surface and a radially inner resin interposed between the permanent magnet and the radially-inner wall surface
Data Source
AI summary
A rotor for a rotating electric machine includes a rotor core having a plurality of magnet-receiving holes formed along a circumferential direction, and a plurality of permanent magnets each of which is received in a corresponding one of the magnet-receiving holes of the rotor core. Each of the magnet-receiving holes has a pair of a radially-outer wall surface and a radially-inner wall surface that are radially opposite to each other. Each of the permanent magnets is fixed in the corresponding magnet-receiving hole of the rotor core by a fixing resin that includes a radially outer resin interposed between the permanent magnet and the radially-outer wall surface of the corresponding magnet-receiving hole and a radially inner resin interposed between the permanent magnet and the radially-inner wall surface of the corresponding magnet-receiving hole. An adhesive strength of the radially outer resin is higher than an adhesive strength of the radially inner resin.