Stator Winding Rigid Bars U-Shaped Insertion
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Solution Overview
Problem
The construction of stator windings using flexible conductors is complex to automate due to their unstable shape, and the use of rigid 'U'-shaped bars introduces complications in differentiation and insertion, leading to potential damage from excessive force and improper direction during assembly.
Innovation Solution
A stator winding with rigid 'U'-shaped bars is designed where all bars have identical cusps widths, allowing for individual insertion and twisting to form electrical paths, reducing stress on the bars and avoiding damage to the insulating enamel, with the method involving central folding, double folds, and precise electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rigid 'U'-shaped bars with differentiated cusp sizes are used to form electrical paths, then the electrical paths can be obtained, but the manufacturing complexity increases significantly and multiple types of bars must be managed during insertion
Solution Approach 1:
The patent applies local quality by creating asymmetry in the bar structure: one leg of the 'U'-shaped bar has a fold while the other leg remains straight. This local differentiation allows the bars to be inserted in a uniform manner while still achieving the required electrical path connections, avoiding the need to manage multiple types of bars with different cusp sizes
Solution Approach 2:
Instead of differentiating the cusps at the entry side of the bars, the invention inverts the approach by differentiating the legs at the exit side through folding. This inversion allows uniform bar insertion while achieving electrical path formation through the folded legs, resolving the contradiction between electrical path formation and manufacturing simplicity
2Productivity
If all 'U'-shaped bars are inserted simultaneously with a single movement, then the insertion process is simplified, but excessive force may damage the insulating enamel on the bars
Solution Approach 1:
The patent applies segmentation by dividing the insertion process into two distinct phases: first inserting all bars simultaneously to achieve high productivity, then performing a second phase where folded legs are twisted and electrical connections are made. This segmentation allows the high-force insertion operation to be separated from the precision connection operations, preventing enamel damage while maintaining insertion efficiency
Solution Approach 2:
The invention applies preliminary action by pre-folding one leg of each 'U'-shaped bar before insertion. This preliminary folding prepares the bars for their final position and electrical connection function, allowing the insertion operation to be performed with uniform force without risking damage to the insulating enamel, as the folded structure guides the insertion process
3Ease of manufacture
If filiform and flexible conductors are used for stator winding, then the winding can be constructed, but the construction process is complex and difficult to automate due to unstable coil shapes
Solution Approach 1:
The patent applies parameter changes by transitioning from flexible conductors to rigid 'U'-shaped bars, fundamentally changing the mechanical properties of the winding elements. The rigid bars maintain a stable shape that can be automatically handled and inserted, eliminating the automation difficulties associated with flexible conductors while still achieving the required electrical winding configuration through strategic folding and connection of the bar legs
Data Source
AI summary
An electric machine includes a stator having a magnetic core crossed longitudinally by a stator slot and stator winding having a phase and series of rigid, U-shaped bars inserted through the slot. The slot defines “entry” and “exit” sides in which cusps and legs of the bars are placed. The legs coming out the “exit” side are twisted through relative double folds each of which defines internal and external folds in opposite directions. Ends of the legs are electrically connected to each other to form electrical paths of the winding. A width of the cusps is identical for the bars. The ends of a pair in a part of the winding are initially not adjacent to each other and folded toward each other to be arranged parallel to each other in a circumferential direction so that the ends touch each other to allow an electrical connection between the ends.