Motor Case Rib Structure for Torsional Stiffness and Weight Reduction
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Solution Overview
Problem
Existing rotary electric machines face challenges in achieving both weight reduction and securing torsional stiffness, leading to increased vibration and noise due to electromagnetic excitation forces, particularly in low rotation ranges.
Innovation Solution
A motor case design featuring a tubular peripheral wall with a flange portion and damping ribs formed by crossing linear ribs, which are arranged to cover the outer periphery between the flange and the end of the stator, enhancing torsional stiffness while reducing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the motor case uses a simple tubular structure for weight reduction, then weight is reduced, but torsional stiffness is insufficient leading to increased vibration and noise
Solution Approach 1:
The peripheral wall is segmented into multiple regions by forming ribs at specific positions. The damping ribs divide the wall into sections that work together to resist torsional deformation, allowing weight reduction while maintaining stiffness through strategic segmentation rather than uniform thickening
Solution Approach 2:
The damping ribs extend in the radial direction from the end portion of the stator, adding a dimensional element that crosses the peripheral wall. This radial extension creates a three-dimensional reinforcement structure that significantly improves torsional stiffness without proportionally increasing weight
2Object-affected harmful factors
If the motor case increases torsional stiffness to reduce vibration, then vibration and noise are reduced, but weight increases
Solution Approach 1:
Instead of uniformly increasing the thickness or density of the entire motor case, damping ribs are formed at specific locations where torsional stress is highest. The ribs are positioned to cross the peripheral wall at strategic points, providing localized reinforcement that effectively reduces vibration and noise without unnecessary weight addition
Data Source
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AI summary
An object of the present invention is to promote weight reduction while improving torsional stiffness of a motor case of a rotary electric machine. A motor case accommodates a stator, a rotor facing an inner periphery of the stator, and a rotating shaft coupled to the rotor. The motor case includes a peripheral wall which is formed in a tubular shape and has a space accommodating the stator and the rotating shaft on an inside, a flange portion which is formed at one end of the peripheral wall and is coupled to an outside, and damping ribs which are formed at an outer periphery of the peripheral wall, are formed between a position crossing the outer periphery of the peripheral wall and the flange portion on an extension of the rotating shaft in a radial direction from an end portion of the stator, and are constituted by a plurality of ribs.