Dishwasher Spray Arm Overload Protection Using Magnetic Decoupling

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Solution Overview

Problem

Existing household dishwashers face issues with spray arm blockages leading to drive system overload, which can cause damage to the drive element or gear unit, especially when handling items or when the spray arm is manually manipulated.

Innovation Solution

A household dishwasher with an overload protection device that automatically switches from a coupled state to a decoupled state when a blockage occurs, using a spring-loaded mechanism to interrupt power transmission between the drive device and the spray arm, preventing damage to the drive system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an active drive is provided to drive the spray arm, then the spray arm can be reliably driven, but the drive system can be overloaded when blockage or manual handling occurs

Engineering Contradiction:
Improvereliable driving of spray armVSAvoidoverload damage to drive system
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a magnetic coupling drive system where the magnetic coupling acts as a predetermined weak link that can slip under overload conditions. The magnetic coupling is designed with specific magnetic strength that allows it to decouple when excessive torque is applied, preventing damage to the drive element and gear unit. This beforehand cushioning mechanism ensures reliable normal operation while protecting against overload damage.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Ease of operation

If the spray arm is manually handled or blocked, then operational flexibility is maintained, but the drive system becomes vulnerable to overload

Engineering Contradiction:
Improvemanual handling capabilityVSAvoiddrive system protection
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The magnetic coupling provides dynamic torque transmission that automatically adapts to load conditions. During normal operation, the magnetic coupling transmits torque efficiently. When manual handling or blockage occurs causing excessive torque, the magnetic coupling dynamically decouples, allowing the spray arm to be manually moved or preventing drive system damage. This dynamic behavior maintains operational flexibility while protecting the drive system.

Inventive Principle:
Principle #15Dynamics

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 overload protection device effectively prevents drive system overload and potential damage by automatically adjusting to blockages, ensuring the safety and longevity of the dishwasher components.

Implementation Method 1

The drive system includes a magnetic coupling. The magnetic coupling comprises a first part located inside a wash chamber of the dishwasher and a second part located outside the wash chamber

Methodology Applied
Scientific EffectMagnetic coupling: Magnetism

Implementation Method 2

The overload protection device is spring-loaded toward the coupled state

Methodology Applied
Scientific EffectSpring mechanism: Spring

Data Source

PatentEP4003128B1Domestic dishwasher
Publication Date: 2025.10.08 BSH HAUSGERATE GMBH
  • EP4003128B1 patent drawingFigure 1
  • EP4003128B1 patent drawingFigure 2
  • EP4003128B1 patent drawingFigure 3

AI summary

The invention relates to a domestic dishwasher (1) comprising a washing container (2), a spray arm (17) for applying washing liquor and/or fresh water (F) to the dishwasher load held in the washing container (2), a drive system (19, 19ʹ) for actively driving the spray arm (17), and an overload protection mechanism (43, 43ʹ), which can move autonomously, if the spray arm (17) becomes blocked, from a coupling position (Z1), in which power is transmitted between the drive system (19, 19ʹ) and the spray arm (17) into a decoupling position (Z2), in which the power transmission between the drive system (19, 19ʹ) and the spray arm (17) is interrupted.