Stepped Stator-Core Fixing Structure to Prevent Shrink-Fit Trapping
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Solution Overview
Problem
The existing stator-core fixing structures face challenges during shrink fitting, where the housing needs to be thermally expanded to accommodate the stator core, but subsequent cooling can cause the housing to shrink, potentially trapping the stator core and reducing workability.
Innovation Solution
The proposed stator-core fixing structure features a stepped design for both the stator core and the housing, where the outer and inner diameters decrease in a specific order, allowing for a non-contact state initially and reducing the contact area, thus preventing the stator core from being caught during cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the housing is thermally expanded to accommodate the stator core during shrink fitting, then the stator core can be inserted into the housing, but when the housing cools and shrinks to its original shape, the stator core may be caught by the inner peripheral surface of the housing, reducing workability
Solution Approach 1:
The inner peripheral surface of the housing is divided into multiple stepped portions with different diameters, and the outer peripheral surface of the stator core is similarly segmented. This segmentation allows different sections to contact at different times during insertion, preventing the stator core from being caught by a continuous tapered surface during thermal contraction.
Solution Approach 2:
Different sections of the inner peripheral surface are given different diameters and contact characteristics through the stepped structure. The first inner peripheral surface portion has a larger diameter than the second portion, creating localized contact zones that control the insertion and fixation process differently at various axial positions.
2Device complexity
If the housing and stator core have uniform contact along the axial direction, then the fixing is simple, but the stator core may be trapped during thermal contraction
Solution Approach 1:
The contact interface is segmented into multiple stepped portions along the axial direction, transforming a simple uniform contact structure into a multi-level contact system. This segmentation ensures reliable insertion by controlling the sequence and distribution of contact points during thermal contraction.
Solution Approach 2:
The fixing structure transitions from a one-dimensional uniform contact along the axis to a multi-dimensional stepped structure with variations in both axial position and radial diameter, creating a more robust insertion mechanism that prevents trapping.
3Strength
If the contact area between the stator core and housing is large, then the fixing strength is increased, but the stator core is more likely to be caught during thermal contraction
Solution Approach 1:
The contact area is distributed into multiple localized zones at different axial positions and diameters rather than a single large continuous area. Each localized contact zone provides sufficient fixing strength while the distribution prevents trapping during thermal contraction.
Solution Approach 2:
The total contact area is segmented into multiple discrete contact regions through the stepped structure, maintaining overall fixing strength while reducing the risk of the stator core being caught in any single large contact zone during thermal contraction.
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 design improves the workability of the fixing process by allowing the stator core to be inserted without the need for initial thermal expansion of the housing, reducing the risk of the stator core being trapped and enhancing the stability of the insertion process.
Implementation Method 1
when the stator core is inserted into the housing, the housing needs to be maintained in a thermally expanded state from a stage before the stator core is inserted into the housing until the stator core moves to a predetermined position in the housing
Data Source
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AI summary
A stator-core fixing structure is a fixing structure of a stator core fixed to a housing (60), and includes a plurality of outer peripheral surface portions that are included in an outer peripheral surface of the stator core (70) and that have outer diameters different from each other, and a plurality of inner peripheral surface portions that are included in an inner peripheral surface of the housing (60) and that have inner diameters different from each other, wherein the plurality of outer peripheral surface portions each correspond to a corresponding one of the plurality of inner peripheral surface portions, and each of the plurality of outer peripheral surface portions contacts the corresponding one of the plurality of inner peripheral surface portions.