Personal Care Plug-Socket Geometry for Moisture-Safe Power Connection

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Solution Overview

Problem

Personal care appliances designed for use in wet conditions face challenges with electrical connectors and power supply devices due to remnant moisture, leading to issues like electrolysis and inadequate ingress protection, which can reduce appliance life and safety.

Innovation Solution

The design incorporates specific socket and plug geometries with optimized curvature ratios and projection/notch features to ensure proper fitting and watertightness, preventing reverse polarity insertion and reducing the risk of electrical creepage, while allowing compatibility with power supply devices of matching or higher IP classes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional plug and socket geometries are used, then ease of manufacture is maintained, but electrical safety and ingress protection are insufficient due to inadequate prevention of moisture ingress and electrolysis

Engineering Contradiction:
Improveelectrical safetyVSAvoidconnector geometry complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The socket and plug incorporate asymmetric geometric features including a projection on the socket circumferential wall and a corresponding notch on the plug circumferential wall. These asymmetric elements prevent reverse polarity insertion and ensure proper orientation during connection, thereby enhancing electrical safety without requiring complex additional components

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The connector design utilizes specific curvature ratios in the circumferential wall segments. The third circumferential wall segment has a radius of curvature where the ratio of radius of curvature to pin distance is at most 0.35, creating optimized curved surfaces that improve sealing and prevent moisture ingress while maintaining manufacturability through standard forming processes

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Object-affected harmful factors

If standard connector designs are used, then manufacturing simplicity is maintained, but protection against remnant moisture and electrolysis is insufficient

Engineering Contradiction:
Improveresistance to moisture and electrolysisVSAvoidcurvature ratio precision
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The invention specifies precise geometric parameters including the curvature ratio (radius of curvature to pin distance ≤ 0.35) and the positions of projection and notch features. These parameter changes optimize the connector geometry to prevent moisture accumulation and electrolysis while remaining compatible with standard manufacturing tolerances and processes

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If simple connector geometries are used, then ease of manufacture is maintained, but compatibility control with appropriate IP classes is insufficient

Engineering Contradiction:
Improvecompatibility with IP classesVSAvoidgeometric fitting structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The asymmetric projection and notch features serve as mechanical interlocking elements that ensure compatibility between appliances and power supply devices with matching or higher IP classes. These features provide geometric fitting control without requiring complex additional mechanisms, maintaining ease of manufacture while enabling IP class adaptability

Inventive Principle:
Principle #4Asymmetry

Data Source

PatentEP4300764A1Personal care appliance, power plug, and kit
Publication Date: 2024.01.03 BRAUN GMBH
  • EP4300764A1 patent drawingFigure 1~3
  • EP4300764A1 patent drawingFigure 4~5
  • EP4300764A1 patent drawingFigure 6

AI summary

Personal care appliances (11, 12), power supply devices (40), and kits comprising the same are disclosed. The personal care appliance (11, 12) and power supply device (40) may have mating connectors.