Rotor Core Assembly via Key Protrusion and Shaft Groove
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Solution Overview
Problem
The existing methods for assembling a rotor core to a rotating shaft in rotary electric machines, such as knurling and press-fitting, increase the number of working steps and costs, and require additional metal molds for casting, leading to potential electrical characteristic deterioration.
Innovation Solution
The rotary electric machine employs a key protrusion arrangement on the rotor core that fits into a shaft key groove, allowing for efficient assembly without the need for knurling or additional end plates, reducing assembly load and compressive stress, and enabling cost reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If knurling is performed on the outer peripheral surface of the rotating shaft to reduce press-fitting load, then the assembly process becomes more complex and costs increase, but the press-fitting load is reduced
Solution Approach 1:
The rotating shaft is preliminarily formed with a key groove before assembly, and the rotor core is preliminarily formed with key protrusions. This preliminary structuring enables simple insertion assembly without requiring knurling processing, thus reducing both the press-fitting load and the number of working steps
Solution Approach 2:
Key protrusions on the rotor core act as intermediaries that engage with the key groove on the rotating shaft. This intermediary mechanism transfers and distributes the assembly load, eliminating the need for knurling while maintaining secure fixation
2Strength
If press-fitting or shrink-fitting is performed at predetermined interference to assemble the rotor core to the rotating shaft, then the assembly is secure, but compressive stress is applied to the rotor core and electrical characteristics deteriorate
Solution Approach 1:
The rotating shaft is preliminarily provided with a key groove and the rotor core is preliminarily provided with key protrusions that fit into the groove. This preliminary configuration enables assembly without interference fitting, avoiding compressive stress on the rotor core while maintaining secure connection
Solution Approach 2:
The key protrusions serve as intermediaries that provide mechanical engagement between the rotating shaft and rotor core. This intermediary mechanism secures the assembly through geometric interlocking rather than compressive interference, preserving the electrical characteristics of the rotor core
3Strength
If a gap is provided between the rotor core and rotating shaft and molten metal is filled in the gap during casting to fix the assembly, then the assembly is secure, but additional metal molds are required and costs increase
Solution Approach 1:
The key groove and key protrusions are preliminarily formed on the rotating shaft and rotor core respectively, enabling direct insertion assembly. This eliminates the need for post-casting molten metal filling and removes the requirement for additional metal molds, reducing manufacturing costs while maintaining assembly security
Data Source
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AI summary
An electric machine capable of easily and efficiently assembling a rotor core to a rotating shaft is provided. A rotor core 405 is formed by laminating a first steel plate 421 consisting of one or more electromagnetic steel plates having a first protrusion portion 430a to be accommodated in a groove portion 451 of a rotating shaft 450 and a second steel plate 422 consisting of one or more electromagnetic steel plates having a second protrusion portion 430b to be accommodated in the groove portion 451 of the rotating shaft 450. The first protrusion portion 430a of the first steel plate 421 has a first engaging portion 431 deformed by a side surface 451a of the groove portion 451 of the rotating shaft 450. At least a part of the first engaging portion 431 of the first steel plate 421 is disposed in a space 432 formed between a second protrusion portion 430b of the second steel plate 422 and the side surface 451a of a groove portion 452 of the rotating shaft 450.