Double-Tube Motor Housing with Non-Contact Sections for Noise Control
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Solution Overview
Problem
The vibration of the inner housing in a rotating electric machine due to rotor rotation leads to noise radiation, which is transferred to the outer housing and emitted outward, and existing double-tube structures for coolant flow channels contribute to this noise radiation.
Innovation Solution
A rotating electric machine with a double-tube structure where the inner housing is fixed to the outer housing by press-fitting or shrink-fitting at one end and bolt-fastening at the other, with non-contacting sections along the circumferential direction to suppress vibration and noise transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a double-tube structure is adopted to form a coolant flow channel without increasing the size of the rotating electric machine, then the cooling efficiency is improved, but noise radiation increases due to vibration transmission from the inner housing to the outer housing
Solution Approach 1:
The fixation portion of the inner housing is segmented into multiple circumferential regions, with non-contacting sections strategically positioned in specific angular ranges. This segmentation allows the housing to be divided into contact regions (for structural support) and non-contact regions (for vibration isolation), thereby reducing noise transmission while maintaining the double-tube coolant channel structure.
Solution Approach 2:
The non-contacting sections act as intermediary zones that decouple the vibration transmission path between the inner and outer housings. By creating gaps in specific circumferential directions, these sections serve as vibration isolation mediators that prevent direct mechanical coupling, thus reducing noise radiation while preserving the cooling function.
2Strength
If the inner housing is fixed to the outer housing by press-fitting or shrink-fitting along the entire circumferential direction, then structural strength is improved, but vibration and noise transmission from the inner housing to the outer housing increases
Solution Approach 1:
The circumferential fixation portion is segmented into contact sections and non-contact sections. The contact sections maintain structural strength by providing fixation points, while the non-contact sections interrupt vibration transmission paths. This selective segmentation allows the structure to simultaneously achieve both strength and vibration isolation.
Solution Approach 2:
Different circumferential regions of the fixation portion are given different properties: contact sections have high coupling (for strength) while non-contact sections have low coupling (for vibration isolation). This local differentiation of quality allows the housing to exhibit both strong structural integrity and effective vibration damping in different spatial locations.
3Object-generated harmful factors
If non-contacting sections are formed at the fixation portion to suppress noise radiation, then noise transmission is reduced, but the complexity of the fixation structure increases
Solution Approach 1:
The fixation structure transitions from a static, uniform contact design to a dynamic, selectively-contacting design. The non-contacting sections allow the housing to have degree of freedom in specific directions, enabling vibration isolation while maintaining overall structural integrity. This dynamic approach reduces noise transmission without requiring complex additional components.
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
The solution effectively restricts noise radiation, particularly when installed on a vehicle, by suppressing vibration transmission and ensuring structural integrity while maintaining a lightweight and cost-effective design.
Implementation Method 1
The inner housing is fixed with the outer housing by press-fitting or shrink-fitting at one end in an axial direction
Implementation Method 2
The inner housing is fixed with the outer housing by press-fitting or shrink-fitting
Implementation Method 3
One or more non-contacting sections, in which an inner circumferential surface of the outer housing and an outer circumferential surface of the inner housing are not in contact with each other, are formed at a fixation portion
Data Source
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AI summary
A rotating electric machine (100F) includes a tube-shaped outer housing (1o) and a tube-shaped inner housing (1i) that forms a coolant flow channel between the outer housing (1o) and it. The inner housing (1i) is fixed with the outer housing by press-fitting or shrink-fitting at one end thereof in its axial direction and fastened with the outer housing at another end by plural bolts. One or more non-contacting sections (1p), in which an inner circumferential surface of the outer housing (io) and an outer circumferential surface of the inner housing (1i) are not in contact with each other, are formed at a fixation portion made by the press-fitting or the shrink-fitting between the outer housing (1o) and the inner housing (1i) along a circumferential direction thereof.