Charging Plug Contact Protection with Spring-Magnet Breakaway Force

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Solution Overview

Problem

Existing contact protection elements for charging connectors, particularly those for electric vehicles, face challenges in achieving a compact design due to space constraints in connector housings, and they often require significant force to move from their initial position safely.

Innovation Solution

A contact protection element made of electrically insulating material with multiple pins connected via a connecting section, incorporating at least one first and one second restoring element. The first restoring element, such as a helical spring, provides a linear force-displacement diagram, while the second restoring element, such as a magnet arrangement, generates a non-linear force-displacement diagram with an initial threshold value to ensure safe movement and reliable return to the initial position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protective device is arranged within the charging socket to enclose high-voltage contacts, then contact protection is improved, but the device complexity and space consumption increase

Engineering Contradiction:
Improvecontact protectionVSAvoidprotective device structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The protective device is segmented into multiple protective elements (first and second protective elements) that can be independently positioned and function. Each protective element can move independently to cover or expose specific contacts, reducing the complexity of moving a single large protective structure while maintaining comprehensive protection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The protective elements are positioned at different radial distances from the connector axis (first protective element at first radial distance, second protective element at second radial distance). This multi-dimensional arrangement allows compact packaging of the protective function within the limited connector space while maintaining effective contact protection.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If the contact protection element is designed to require noticeable force to move from initial position, then safety is improved, but the ease of operation deteriorates

Engineering Contradiction:
ImprovesafetyVSAvoidmovement ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The protective elements are designed to be movable rather than fixed, allowing dynamic adjustment between protected and accessible states. The elements can be displaced radially by the plugging force during connection, automatically transitioning from a protective state to an operational state without requiring manual intervention or excessive force.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The protective elements are pre-positioned in an initial position that provides contact protection before plugging occurs. This preliminary protective state is automatically maintained until the plugging action itself provides sufficient force to displace the elements, ensuring safety is established before operation begins.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If the connector is designed with angled shape as revolving connector, then adaptability is improved, but the available installation space deteriorates

Engineering Contradiction:
Improveconnector shape adaptabilityVSAvoidinternal installation space
Core Design Contradiction:
Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The protective elements utilize the radial dimension (distance from connector axis) to arrange protective functions at different levels. This allows the protective device to fit within the limited internal space of the angled connector housing while maintaining effective coverage of contacts, as the radial arrangement efficiently uses the available cross-sectional area at each position along the connector length.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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

The solution enables a compact, safe, and reliable contact protection element that requires a noticeable force to move from its initial position, ensuring effective prevention of accidental contact with live parts and efficient return to the initial position after use.

Implementation Method 1

The first return element can, for example, have a linear force-displacement diagram with respect to its movement from its initial position and can therefore preferably be designed as a return spring, in particular as a helical spring

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The second return element can have a non-linear force-displacement diagram with respect to the same movement, in particular having a maximum to be overcome initially, and can therefore preferably be designed as a magnet arrangement, in particular either as a two-part permanent magnet or as a magnet and a metal part

Methodology Applied
Scientific EffectMagnetism: Magnetism

Data Source

PatentEP4572029A1Contact protection element for a plug connector
Publication Date: 2025.06.18 HARTING AUTOMOTIVE GMBH & CO KG
  • EP4572029A1 patent drawingFigure 1a~1b
  • EP4572029A1 patent drawingFigure 1c~1d
  • EP4572029A1 patent drawingFigure 1e~1f

AI summary

In order to achieve a particularly compact design for a contact protection element (4, 4') of a car charging plug - i.e. a wallbox-mountable charging socket or a cable connector - with a force-displacement diagram that is particularly effective in terms of safety and haptics, the following is proposed: The contact protection element (4, 4') consists of an electrically insulating material, e.g., plastic. The contact protection element (4, 4') has several, in particular four, pins (41) that point in a common direction and are mechanically connected to one another via a connecting section (44, 44'). The pins (41) are each intended to be inserted through a socket contact of the plug-in connector. Furthermore, the contact protection element (4, 4') has at least one reset element. The reset element can, for example, be a spring, in particular a helical spring (3). In addition, a second reset element, e.g.,a magnet arrangement (30, 30') is used to generate a non-linear course of the resulting force-displacement diagram, so that when plugging in a mating connector, a threshold value, namely a so-called "breakaway torque", must initially be overcome.