Low-Resistance Electrical Connection for Motor Vehicle Control Units

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Solution Overview

Problem

Existing electrical connections in motor vehicle control units, particularly those with electric drives, face challenges in achieving low resistance and minimizing power loss due to high ohmic contact resistance, especially when handling currents of several hundred amperes.

Innovation Solution

An electrical connection system utilizing an electrically conductive sleeve and a bolt with a pressing device, where the bolt is guided through the sleeve to press an end section of an electrical connection cable against the sleeve's end face, creating a full-area contact and reducing ohmic resistance by generating high contact pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional electrical connections are used in control units, then the structure is simple and easy to manufacture, but the ohmic contact resistance is high leading to significant power loss

Engineering Contradiction:
Improvepower lossVSAvoidconnection structure complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The electrical connection is divided into separate functional components: a conductive sleeve for electrical contact, a bolt for mechanical fastening, and a pressing device for applying contact pressure. This segmentation allows each component to be optimized for its specific function, resulting in lower contact resistance while maintaining manufacturing simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the physical parameters of the connection by introducing a pressing device that applies high contact pressure (force parameter) and ensures full-area contact (surface area parameter). These parameter changes directly reduce ohmic contact resistance and power loss according to the electrical contact laws.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If high contact pressure is applied to reduce ohmic resistance, then the electrical conductance increases, but the mechanical stress on the connection components increases

Engineering Contradiction:
Improveelectrical connection reliabilityVSAvoidmechanical strength of connection components
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The conductive sleeve acts as an intermediary component between the bolt and the electrical connection cable. It distributes the mechanical stress from the bolt over a larger area while maintaining high contact pressure at the electrical contact interface, thus protecting the bolt from excessive stress while ensuring reliable electrical contact.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The connection system uses composite construction with different materials optimized for specific properties: the bolt provides mechanical strength, the conductive sleeve provides electrical conductivity and stress distribution, and the pressing device provides controlled force application. This composite approach balances mechanical strength and electrical reliability.

Inventive Principle:
Principle #40Composite materials

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 configuration significantly reduces electrical power loss during operation by increasing the effective contact surface and decreasing ohmic resistance, ensuring reliable and efficient energy transfer to the inverter and other electrical components in electric vehicles.

Implementation Method 1

an electrical galvanic connection, in particular an electrical connection created by touching two contacts, increases the conductance of the connection with a high contact pressure

Methodology Applied
Scientific EffectGalvanic contact: Conduction (electrical)

Implementation Method 2

the ohmic contact resistance of the contact decreases

Methodology Applied
Scientific EffectOhmic resistance: Electrical Resistance

Data Source

PatentEP3084887B1Control device comprising a low-resistance electrical connection
Publication Date: 2018.12.12 ROBERT BOSCH GMBH
  • EP3084887B1 patent drawingFigure 1
  • EP3084887B1 patent drawingFigure 2
  • EP3084887B1 patent drawingFigure 3

AI summary

The invention relates to a control device (1) for a motor vehicle, in particular a motor vehicle comprising an electric drive, comprising a housing (2) which encloses a cavity (3), wherein the control device (1) has a power apparatus (4) arranged in the cavity (2), in particular an inverter. A housing wall (21) of the housing has an aperture (5). An electrical connection (6) of the control device (1) is passed through the aperture (5) and has an electrically conductive sleeve (7) and a bolt (8). The sleeve (7) is electrically connected detachably to the power apparatus (4). The bolt (8) is passed through the sleeve (7) and is designed to hold an end section (10) of an electrical connection cable (9) fixedly and to press the end section against a sleeve end, in the form of an end face (15, 16), of the sleeve (7) and thus to connect the electrical connection cable (9) to the connection (6).