Rotor Groove Segmentation for High-Speed Potting Stress
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Solution Overview
Problem
High-speed electric machines for hybrid and electric vehicles face mechanical stress due to binding seams formed during potting or encapsulation, which can lead to crack formation and reduced strength at high rotational speeds.
Innovation Solution
A rotor design featuring grooves with separating elements that guide the potting compound, forming groove chambers and avoiding critical binding seams, allowing for stable encasing of windings and reduced mechanical stress through controlled flow and positioning of the potting compound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If potting compound is applied during encapsulation, then windings are encased and protected, but binding seams occur when flow fronts meet, reducing strength and causing cracks at high rotational speeds
Solution Approach 1:
The rotor circumference is divided into multiple segments by introducing separating elements that create groove chamber segments. Each groove chamber segment is enclosed by separating elements arranged around rotor teeth, which partition the potting compound flow paths. This segmentation prevents multiple flow fronts from meeting and forming binding seams, thereby maintaining structural integrity and strength at high rotational speeds.
2Power
If high rotational speeds are achieved for high power density, then motor performance improves, but mechanical loads and stress states increase, leading to crack formation in potting compound
Solution Approach 1:
By segmenting the rotor structure into multiple groove chamber segments using separating elements, the mechanical stress is distributed across multiple independent enclosed chambers rather than a continuous structure. This segmentation reduces stress concentration and prevents crack propagation, enabling the rotor to withstand high rotational speeds required for high power density applications.
3Reliability
If separating elements are arranged around rotor teeth to form groove chamber segments, then binding seams are avoided, but device complexity increases
Solution Approach 1:
The separating elements serve multiple functions simultaneously: they define groove chamber segments, guide potting compound flow, prevent binding seam formation, and provide structural support around rotor teeth. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving reliable encapsulation.
4Manufacturing precision
If groove chambers are formed to guide potting compound, then binding seams are eliminated, but manufacturing complexity increases
Solution Approach 1:
The separating elements are pre-installed on the rotor before the potting compound is applied. This preliminary arrangement of separating elements creates predefined groove chamber segments that guide the potting compound flow during encapsulation, ensuring that binding seams are avoided without requiring complex post-manufacturing adjustments or modifications.
Data Source
AI summary
A rotor for an electrical machine has at least one groove, the at least one groove includes a groove bottom and groove walls. A separating element is provided between the groove walls, and extends along the groove. The separating element is arranged on the groove bottom, at least in sections, such that groove chambers are formed along the groove.