Segmented Rotor Core with Covered Weight-Reduction Holes
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Solution Overview
Problem
Existing rotor designs face challenges in reducing weight while maintaining productivity due to the reduction in axial end surface area when holes are provided for weight reduction, leading to inefficient filler injection and decreased drive efficiency in rotating electric machines.
Innovation Solution
A rotor core constructed by axially stacking sheet members with a magnet-inserted hole portion and a separate second hole portion, where the second sheet member covers the second hole portion, allowing for efficient filling material injection and weight reduction, improving drive efficiency and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a hole is provided in the rotor core for reducing weight, then the weight of the rotor core is reduced, but the area of the axial end surface is reduced and thus the injection efficiency of the filler is deteriorated
Solution Approach 1:
The rotor core is segmented into multiple sheet members stacked axially. The first sheet member contains both the magnet-inserted hole portion and the second hole portion for weight reduction, while the second sheet member covers the second hole portion. This segmentation allows the weight reduction hole to exist without reducing the effective injection surface area, as the covering sheet member provides the necessary surface for jig placement and filler injection.
Solution Approach 2:
The solution moves the weight reduction function to a different dimensional arrangement by stacking sheet members axially. The second hole portion is created in the first sheet member but covered by the second sheet member in the axial direction, effectively hiding the hole from the radial injection path while maintaining weight reduction. This dimensional arrangement allows simultaneous achievement of weight reduction and maintained injection efficiency.
2Weight of moving object
If a hole is provided in the rotor core for reducing weight, then the weight of the rotor core is reduced, but the productivity of the rotor is deteriorated
Solution Approach 1:
The rotor core is divided into multiple sheet members that can be manufactured separately and then stacked. This segmentation allows the second hole portion to be formed in the first sheet member without affecting the overall productivity, as each sheet member can be prepared independently and the covering sheet member restores the surface integrity needed for efficient filler injection in the final assembled rotor.
3Weight of moving object
If the area of the axial end surface is reduced, then weight reduction holes can be provided, but the injection efficiency of the filler is deteriorated
Solution Approach 1:
The invention resolves the area reduction issue by utilizing the axial dimension. The second hole portion is formed in the first sheet member but is covered by the second sheet member in the axial direction, so the effective axial end surface area available for injection is maintained. The weight reduction is achieved by removing material in the radial direction through the covered hole, while the covering sheet member preserves the surface area needed for injection operations.
Data Source
AI summary
A rotor includes: a rotor core fixedly attached to a rotational shaft and having a magnet-inserted hole portion; a magnet inserted into the magnet-inserted hole portion; and a resin portion injected into the magnet-inserted hole portion. The rotor core is constructed by axially stacking a plurality of electromagnetic steel sheets. The electromagnetic steel sheets include: an electromagnetic steel sheet having the magnet-inserted hole portion and a weight-reducing-purpose hole portion provided separately from the magnet-inserted hole portion; and an electromagnetic steel sheet located on at least one axial end of the rotor core and having a portion covering the hole portion formed in the electromagnetic steel sheet.