Stator Lead Wire Turnback Design for Vibration Stress Reduction
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Solution Overview
Problem
The concentration of lead wires in a single area in rotating electric machines, such as those in electric vehicles, leads to excessive tensile and compressive stress due to vibration, necessitating measures for improved durability and reliability while maintaining uniform wire resistance and minimizing the salient region for clearance.
Innovation Solution
A stator design with lead wires congregating in a single area, featuring inclining wire portions and turnback portions greater than 90°, which improves rigidity and allows for optimal adjustment of wire lengths to equalize resistance, while minimizing the salient region and ensuring sufficient clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If lead wires are concentrated in a single area to facilitate connections, then ease of operation is improved, but tensile force and compressive stress increase due to vibration
Solution Approach 1:
The lead wire is formed with a curved configuration including an inclining wire portion and a turnback portion instead of a straight arrangement. The turnback portion creates a bent structure that absorbs tensile and compressive forces generated by vibration, preventing excessive stress on the connection points while maintaining the concentrated arrangement for ease of connection.
Solution Approach 2:
The inclining wire portion is designed with a predetermined inclination angle relative to the axial direction, creating a built-in stress absorption mechanism that cushions against vibration forces before they reach the connection points. This pre-configured geometric feature provides inherent protection against vibrational damage.
2Device complexity
If lead wires are concentrated in a single area, then device complexity is reduced, but wire resistance uniformity becomes difficult to control
Solution Approach 1:
The inclination angle of the inclining wire portion is set to a specific value within the range of 30° to 60° relative to the axial direction. This parameter optimization allows the lead wire to absorb vibration forces effectively while maintaining uniform wire resistance across all stator coils, resolving the conflict between structural simplicity and manufacturing precision.
3Area of stationary object
If the salient region is minimized for clearance, then space utilization is improved, but lead wire arrangement becomes more constrained
Solution Approach 1:
The lead wire configuration utilizes three-dimensional spatial arrangement with the inclining wire portion extending at an angle and the turnback portion creating a bent structure. This dimensional approach allows the lead wire to be arranged within a minimized salient region while maintaining adequate space for connection, effectively resolving the conflict between compactness and manufacturability.
Data Source
AI summary
A new rotor for a rotating electric machine assuring outstanding durability and reliability against vibration and facilitating equalization of resistances among a plurality of rotor coils, while allowing the leading ends of a plurality of lead wires to be disposed so as to congregate in one area, is provided. A plurality of stator coils 102 wound at a cylindrical stator core 101 each include leader portions led out from one of two ends of a slot along the axial direction and extending astride a plurality of slots. Lead wires 300 each formed at one end of a stator coil 102 are disposed so that their leading ends, oriented in the same direction, congregate in a single area. In a leader portion where a lead wire 300 is located, a turnback portion 400, made to turn back with an angle equal to or greater than 90° from an inclining wire portion 113, which is led out with an inclination along a predetermined direction from the slot, is formed.