Stator Winding Retention via Variable Slot Width and Interference Fit
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Solution Overview
Problem
Current designs for electric machine stators face challenges in reliably retaining conductive windings, leading to premature failure due to inadequate varnish application and improper winding retention.
Innovation Solution
The stator design features radially varying slots with narrower widths near the periphery, combined with deformed windings that exceed the narrowest slot width, creating a frictional interference to securely retain the windings, and a method involving a widening tool to achieve this retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If varnish is applied to bond windings to the stator, then winding retention is improved, but the process complexity and reliability risk increase due to difficult application requirements
Solution Approach 1:
The patent removes the varnish bonding process entirely from the winding retention system. Instead of applying varnish to adhesive windings to the stator, the invention uses a mechanical interference fit achieved by deforming the windings to exceed the narrowest slot width, eliminating the need for varnish application and its associated complexity and reliability risks.
Solution Approach 2:
The patent replaces the chemical bonding mechanism (varnish adhesion) with a mechanical retention mechanism (interference fit through deformation). The deformed windings create direct mechanical contact and frictional engagement with the slot walls, substituting the varnish bonding system with a purely mechanical retention system that is more reliable and less complex.
2Reliability
If windings are deformed to exceed slot width for retention, then winding retention is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary deformation to the windings before they are installed in the slots. By pre-deforming the windings to exceed the narrowest slot width before installation, the manufacturing process is simplified because the deformation is performed once on loose windings rather than attempting to deform them after installation. This preliminary action ensures proper retention while maintaining ease of manufacture.
3Reliability
If slot width is reduced for better retention, then winding retention is improved, but the ability to insert windings deteriorates
Solution Approach 1:
The patent applies local quality variation to the slot geometry by creating a narrowest width at a specific location within the slot. The slot has varying width along its length, with the narrowest portion positioned to engage the deformed windings. This local narrowing provides strong retention at the engagement point while the rest of the slot maintains sufficient width to facilitate winding insertion and accommodate the deformed windings.
Solution Approach 2:
The patent changes the geometric parameter of the slot from a uniform width to a variable width profile. By varying the slot width along its length and creating a specific narrowest width at a strategic position, the design achieves both easy insertion (sufficient width at insertion points) and strong retention (narrowest width at engagement position). The deformed windings are inserted when the slot is sufficiently wide, then retained when they engage the narrowest portion.
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 solution enhances winding retention within the slots, preventing dislodgment and ensuring reliable operation of electric machines by maintaining effective frictional engagement and minimizing electrical isolation damage.
Implementation Method 1
creating a frictional interference to securely retain the windings
Data Source
AI summary
Disclosed herein is an electric machine stator. The electric machine stator includes a tubular body with a plurality of radial slots formed into a perimetrical surface thereof, each of the plurality of slots having a width that varies over at least a portion of a radial depth of the slot such that the slot width is narrower near the perimetrical surface than the slot width further from the perimetrical surface. The stator further includes at least one winding positioned within each of the plurality of slots and at least one of the at least one winding is deformed within the slot such that at least one dimension of the at least one winding is greater than a narrowest slot width dimension thereby retaining the winding within the slot.