Bearing Insulation for Rotating Electrical Machine Neutral Points
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Solution Overview
Problem
The proximity of neutral points or phase outputs/inputs of the stator winding to the bearing in electrical machines increases the risk of accidental electrical contact, which can lead to safety and operational issues.
Innovation Solution
An electrical insulation member is placed around the bearing with openings to prevent contact between the bearing and the conductor ends, extending partially through the bearing openings and featuring annular or tabbed designs to cover the neutral points, made of plastic with snap-fit lugs for secure attachment, and optionally includes notches and grooves for heat sink fins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the neutral points or phase outputs/inputs of the stator winding are located close to the bearing, then the machine structure is compact, but the risk of accidental electrical contact between winding conductor and bearing increases
Solution Approach 1:
An electrical insulation member is introduced as an intermediary element between the stator winding conductors and the bearing. This insulation member extends through the bearing opening and positions itself between the neutral points and the bearing surface, preventing direct contact while allowing the compact structure to be maintained. The mediator resolves the contradiction by providing electrical isolation without requiring increased spacing.
2Reliability
If an electrical insulation member is added to prevent contact between conductors and bearing, then safety is improved, but device complexity increases
Solution Approach 1:
The electrical insulation member is designed to perform multiple functions simultaneously: it provides electrical insulation between the conductors and bearing, acts as a mechanical support element, and can guide the conductors during assembly. By combining multiple functions into a single component, the solution improves safety without proportionally increasing device complexity.
Solution Approach 2:
The insulation member is implemented as a thin, flexible insulating element that can adapt to the geometry of the bearing and conductors. This thin-film approach provides effective insulation while minimizing the added volume and complexity compared to rigid insulation structures.
3Object-affected harmful factors
If the insulation member extends through the bearing opening, then electrical protection is enhanced, but air circulation and cooling may be affected
Solution Approach 1:
The insulation member is designed with non-uniform geometry, featuring localized extensions or protrusions that specifically target the regions where conductors are most vulnerable to contact with the bearing. The bulk of the bearing opening remains open to allow air circulation, while only the necessary local areas are blocked by the insulation member. This resolves the contradiction by providing protection only where needed while preserving overall cooling efficiency.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a rotating electrical machine (1), in particular an alternator or a starter-alternator for a motor vehicle, comprising: - at least one bearing (48) provided with at least one opening (49) leading outside the bearing, - a stator (16) comprising an electrical winding (18), this winding comprising a plurality of electrical conductors and at least one of these conductors comprising an end forming an electrical neutral point of the winding, - an electrical insulation element (70) arranged to prevent any contact between the bearing (48) and said end of conductor forming a neutral point, this insulation element extending at least partially through the opening of the bearing and being at least partially outside the bearing, this electrical insulation element being further arranged to be at least partially supported on an external surface (71) of the bearing.