Electric Compressor Stator Shrink Fit Grooves
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Solution Overview
Problem
Electric compressors experience vibration transmission and noise issues due to shrink-fitted stators, which reduces the durability of casing components when attempting to increase the holding force.
Innovation Solution
The design includes protrusions on the casing with axial grooves that increase contact pressure with the stator, allowing for a higher holding force without increasing the shrink-fitting allowance, thereby enhancing durability and reducing vibration transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the shrink-fitted area between the stator and casing is reduced to decrease vibration transmission, then noise is reduced, but the holding force of the stator becomes insufficient
Solution Approach 1:
The invention applies local quality by creating protrusions with grooves at specific locations on the casing inner periphery. These localized structural features concentrate the shrink-fitting force at the circumferential edges of the protrusions while maintaining discontinuous shrink-fitted areas. This allows vibration transmission to be reduced through discontinuous contact while the grooves ensure sufficient holding force by concentrating pressure at key interfaces.
2Force
If the allowance for shrink fitting is increased to ensure sufficient holding force, then the holding force is improved, but stress on the casing increases and durability is reduced
Solution Approach 1:
The grooves in the protrusions create localized stress distribution patterns. By concentrating the shrink-fitting allowance at the circumferential edges where the grooves are located, the design achieves sufficient holding force without distributing excessive stress across the entire casing structure. This localized concentration of deformation allows the casing to maintain durability while providing adequate holding force.
3Object-generated harmful factors
If discontinuous shrink-fitted areas are used to reduce vibration transmission, then noise is reduced, but the force for holding the stator decreases
Solution Approach 1:
The protrusions with grooves create localized high-contact-pressure regions at their circumferential edges. This allows the shrink-fitted areas to be discontinuous (reducing overall vibration transmission and noise) while the localized edges provide concentrated holding force. The grooves ensure that the contact pressure is maximized at the interfaces where holding force is critical.
4Force
If the contact pressure between protrusions and stator is increased to improve holding force, then holding force is improved, but stress on the casing increases
Solution Approach 1:
The grooves in the protrusions create a localized stress distribution pattern where high contact pressure is concentrated at the circumferential edges. This allows the casing to withstand the necessary holding force without experiencing excessive overall stress. The localized nature of the high-pressure zones prevents stress propagation throughout the entire casing structure, maintaining durability.
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 effectively increases the holding force of the stator while maintaining casing durability and reducing vibration and noise transmission.
Implementation Method 1
the protruding end surfaces of the protrusions are fixed to an outer periphery of the stator by shrink fitting at contact interfaces therebetween
Data Source
AI summary
In order to ensure shrink-fitted components, such as a casing, to have a desirable force for holding a stator while maintaining a desirable durability, an electric compressor in which the stator is fixed to the casing by shrink fitting is configured as follows. Three protrusions 41f are provided protruding radially inside from the peripheral wall of a first casing 41 so as to be spaced apart from each other in the circumferential direction, and each protrusion 41f is provided with a groove 41f2 which extends in the axial direction in a circumferentially central portion of the protrusion 41f. Protruding end surfaces 41f1 of the protrusions 41f are fixed to the outer periphery of the stator 3 by shrink fitting at contact interfaces therebetween.