Segmented Busbar Interface for Easier E-Axle Manufacturing

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Solution Overview

Problem

Existing manufacturing processes for busbars with complex shapes result in high waste and tool wear, reducing the economic efficiency and handling difficulties due to their complexity.

Innovation Solution

The busbars are designed with two less complex punched and bent parts that are connected using a mechanical joining process, enhanced by complementary undercut recesses and engagement sections, and overmolded with an injection molding compound for robustness and protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If busbars with complex shapes are produced using punching and bending processes, then the manufacturing capability is achieved, but waste and tool wear increase significantly

Engineering Contradiction:
Improvemanufacturing capabilityVSAvoidwaste
Core Design Contradiction:
Ease of manufactureVSLoss of substance

Solution Approach 1:

The busbar is divided into multiple punched-bent parts that are connected together. Each individual part has a simpler shape that can be manufactured with less waste and tool wear, while the assembly of multiple parts creates the required complex overall geometry. This segmentation allows standard punching tools to be used effectively without requiring complex custom tooling for the entire busbar shape.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If busbars with complex shapes are produced using punching and bending processes, then the manufacturing capability is achieved, but tool wear increases significantly

Engineering Contradiction:
Improvemanufacturing capabilityVSAvoidtool life
Core Design Contradiction:
Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

By segmenting the busbar into multiple simpler punched-bent parts, the punching tools only need to create basic shapes rather than complex geometries. This reduces the complexity and stress on the punching tools, thereby extending their service life and reducing tool wear.

Inventive Principle:
Principle #1Segmentation

3Shape

If punched and bent parts have complex shapes with many bends, then the required geometry is achieved, but handling becomes difficult

Engineering Contradiction:
ImprovegeometryVSAvoidhandling
Core Design Contradiction:
ShapeVSEase of operation

Solution Approach 1:

The complex busbar geometry is achieved by assembling multiple simpler punched-bent parts rather than creating one complex part. Each individual part has fewer bends and is easier to handle during manufacturing and assembly, while the final assembled structure achieves the required complex geometry for the electrical connection.

Inventive Principle:
Principle #1Segmentation

4Strength

If two punched and bent parts are connected by mechanical joining, then the connection strength is improved, but the manufacturing process complexity increases

Engineering Contradiction:
Improveconnection strengthVSAvoidmanufacturing process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The mechanical joining process is combined with the punching and bending operations in an integrated manufacturing approach. The punched-bent parts are designed with features that facilitate direct mechanical connection, and the joining process is performed as part of the overall manufacturing flow rather than as a separate complex operation. This merging of operations maintains connection strength while controlling process complexity.

Inventive Principle:
Principle #5Merging (Combining)

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 design reduces waste and tool wear, enhances manufacturing efficiency, and provides a robust, environmentally protected connection suitable for various component arrangements.

Implementation Method 1

an interface device which has three busbars (20) which are permanently connected to one another by an injection-molding compound (22)

Methodology Applied
Scientific EffectInjection molding:

Implementation Method 2

the first punched-bent part is electrically conductively connected to the second punched-bent part

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP4576438A1Interface device for electrical connection between an electric motor and an inverter, for example in an e-axis, method for producing the interface device and e-axis
Publication Date: 2025.06.25 ROBERT BOSCH GMBH
  • EP4576438A1 patent drawingFigure 1
  • EP4576438A1 patent drawingFigure 2
  • EP4576438A1 patent drawingFigure 3

AI summary

The invention relates to an interface device (10) for the electrical connection between an electric motor and an inverter, for example in an electric axle for a vehicle, with three busbars (20) which are permanently connected to one another by an injection-molding compound (22), wherein each of the three busbars (20) comprises a first punched and bent part (21a) made of an electrically conductive material and a second punched and bent part (21b) made of an electrically conductive material, wherein the first punched and bent part (21a) is electrically conductively connected to the second punched and bent part (21b).