DC Plug and Socket Structure for AC Interface Differentiation

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Solution Overview

Problem

Current DC plugs and sockets are often confused with AC plugs and sockets due to similar structural forms, making them unsuitable for daily use and not representative of DC systems, and existing solutions are heavy, costly, and complex, lacking a representative interface for DC microgrids.

Innovation Solution

A DC plug and socket design featuring arc-shaped contact surfaces and symmetrically arranged conductors, allowing for unlimited forward and reverse plugging, with a unique butterfly-wing type center contact structure to increase contact area and reduce resistance, and arc-shaped transitional connections to manage creepage distance, distinguishing it from AC interfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If DC plugs and sockets are designed following three-phase AC plugs and sockets with plug pins and jacks, then the structural form is familiar and easy to manufacture, but they are easily confused with AC plugs and sockets and are not suitable for daily use

Engineering Contradiction:
Improvemanufacturing easeVSAvoidusability
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

The patent applies asymmetry by designing the DC plug with a unique butterfly-wing type center contact structure that is fundamentally different from traditional AC plug pin configurations. This asymmetric design makes the DC plug visually distinguishable from AC plugs, preventing confusion during operation while maintaining manufacturability through standardized production processes.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent inverts the traditional plug design concept by using a center contact structure with arc-shaped contact surfaces instead of external plug pins. This inversion creates a fundamentally different interface form that is clearly distinguishable from AC plugs while simplifying the connection mechanism.

Inventive Principle:
Principle #13The other way round (Inversion)

2Reliability

If aviation plugs are used for DC interfaces, then the connection reliability is high, but the weight is heavy, cost is high and the structure is complicated

Engineering Contradiction:
Improveconnection reliabilityVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the essential functional requirements of aviation plugs (reliable electrical connection) while removing the excessive structural complexity, heavy weight, and high cost characteristics. The design achieves this by using a simplified center contact structure with arc-shaped contact surfaces that provides reliable connection without the cumbersome aviation plug configuration.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent adopts a more economical design approach by creating a DC plug structure that is simpler and less expensive than aviation plugs, suitable for consumer electronics and daily use applications where extreme durability is not the primary requirement.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If the center contact side surfaces are made flat, then the manufacturing is simple, but the contact area is small and contact resistance is high

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidcontact area
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies curvature by designing the center contact side surfaces with arc-shaped geometries instead of flat surfaces. This curved design increases the contact area between mating plugs, reducing contact resistance and improving electrical connection quality while remaining compatible with standard manufacturing processes.

Inventive Principle:
Principle #14Spheroidality (Curvature)

4Ease of operation

If the plug structure is made symmetric for unlimited forward and reverse plugging, then the ease of operation is improved, but the creepage distance management becomes more difficult

Engineering Contradiction:
Improveplugging flexibilityVSAvoidarc discharge risk
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent addresses the creepage distance challenge in symmetric designs by utilizing three-dimensional spatial arrangement and arc-shaped transitional connections. This dimensional approach allows the design to maintain symmetry for easy operation while managing electrical creepage paths through careful 3D configuration of the contact surfaces and insulating structures.

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

Data Source

PatentEP3905455B1Direct current plug, direct current socket, and consumer
Publication Date: 2024.06.12 GREE ELECTRIC APPLIANCE INC OF ZHUHAI
  • EP3905455B1 patent drawingFigure 1~2
  • EP3905455B1 patent drawingFigure 3~4
  • EP3905455B1 patent drawingFigure 5

AI summary

The present disclosure relates to a direct current (DC) plug, a DC socket and electric equipment. The DC plug is configured to be connected to a DC socket to supply power to an electrical equipment. The DC plug includes: a center contact, including a first center contact side surface, a second center contact side surface, a third center contact side surface and a fourth center contact side surface, wherein the first center contact side surface and the second center contact side surface are oppositely disposed, and the third center contact side surface and the fourth center contact side surface are oppositely disposed; first plug current conductors, disposed on the first center contact side surface and the second center contact side surface; and second plug current conductors, disposed on the third center contact side surface and the fourth center contact side surface, wherein the first plug current conductors are configured to be connected to one of the positive pole and the negative pole of a power source, and the second plug current conductors are configured to be connected to the other of the positive pole and the negative pole of the power source. The form of the DC plug provided by the present disclosure is adopt to avoid confusion with three-phase AC plugs and sockets.