Stator Busbar Overmolding for Wet-Environment Insulation

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Solution Overview

Problem

Existing methods for manufacturing stator-assemblies for electric machines in damp and wet environments lack efficient electrical insulation and result in increased manufacturing time and costs due to complex handling and material usage.

Innovation Solution

The method involves overmolding the busbar with electrically insulating material before mounting it on the stator, followed by connecting the coils and overmolding the connection points with additional insulating material, simplifying the process and improving insulation precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the busbar is overmolded with electrically insulating material before mounting on the stator, then the electrical insulation precision is improved and handling is simplified, but the manufacturing process requires additional steps

Engineering Contradiction:
Improveelectrical insulation precisionVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The busbar is overmolded with electrically insulating material in advance, before being mounted on the stator. This preliminary action ensures precise electrical insulation is achieved during a dedicated overmolding step, allowing the busbar to be fully insulated before handling and connection operations, thereby improving insulation precision while organizing the complexity into sequential steps.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If the busbar is overmolded before mounting on the stator, then the handling during manufacture is simplified, but the manufacturing time increases due to additional processing steps

Engineering Contradiction:
Improvehandling ease during manufactureVSAvoidmanufacturing time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The busbar is overmolded with insulating material before mounting, which simplifies subsequent handling operations. The pre-insulated busbar can be directly positioned and connected without requiring additional insulation operations during assembly, improving ease of operation despite the added preliminary step.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The overmolding of the busbar is integrated into the manufacturing flow as a preliminary step that combines insulation application with busbar preparation. This merging of functions allows the insulating material to be applied in a dedicated process step while the busbar is still in a convenient state for overmolding, optimizing the balance between handling ease and manufacturing time.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If the connection points between busbar and stator are overmolded with electrically insulating material, then the electrical insulation is improved, but the consumption of electrically insulating material increases

Engineering Contradiction:
Improveelectrical insulation reliabilityVSAvoidconsumption of electrically insulating material
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The busbar is overmolded with electrically insulating material before mounting on the stator, which ensures that the bulk of the insulation is applied in advance. This preliminary overmolding covers the entire busbar surface, reducing the need for additional insulating material during subsequent connection operations, while still ensuring reliable insulation at connection points.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The connection points between the busbar and stator are selectively overmolded with electrically insulating material. This localized application ensures that insulation is precisely applied only where electrical insulation is critical, rather than covering the entire assembly, thereby improving insulation reliability at key locations while minimizing material consumption.

Inventive Principle:
Principle #3Local quality

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 approach reduces manufacturing time and costs while enhancing electrical insulation, making it suitable for use in wet environments, such as electric compressors in air-conditioning systems.

Implementation Method 1

the busbar is first overmolded with an electrically insulating material

Methodology Applied
Scientific EffectOvermolding:

Implementation Method 2

the connection points between the busbar and the stator are overmolded with an electrically insulating material

Methodology Applied
Scientific EffectOvermolding:

Data Source

PatentEP4485757A1Method for manufacturing a stator-assembly for an electric machine
Publication Date: 2025.01.01 MAHLE INT GMBH
  • EP4485757A1 patent drawingFigure 1~2
  • EP4485757A1 patent drawingFigure 3~4
  • EP4485757A1 patent drawingFigure 5~6

AI summary

The present invention relates to a method for manufacturing a stator-assembly (1) for an electric machine (100), which comprises a stator (2) and a busbar (4) for electrically connecting coils (6) of the stator (2) to a controller (101) of the electric machine (100). Simplified and cost-effective manufacture with reduced cycle times is achieved by encasing the busbar (4) with an electrically insulating busbar material and then electrically connecting it to the coils (4), with joint sections (8) in which the coils (4) are electrically connected to the busbar (4) also being separately electrically insulated after said electrical connecting. The invention also relates to a stator-assembly (1) manufactured in this way and to an electric machine (100) having such a stator-assembly (1).