Magnetic Dishwasher Spray Arm Drive for Reliable Rotation

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Solution Overview

Problem

Existing automatic dishwashers rely on hydraulic systems to rotate spray arms, which can be inefficient and may not effectively distribute wash liquid for thorough cleaning, especially at high temperatures or when encountering obstacles.

Innovation Solution

A magnetic system comprising a first magnetic coupler outside the wash chamber and a second magnetic coupler inside, magnetically coupled to the sprayer, transfers rotational energy from a motor to rotate the sprayer arms, allowing for efficient wash liquid distribution and improved cleaning performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hydraulic systems are used to rotate spray arms, then the spray arms can be rotated using wash liquid flow, but the system becomes inefficient and cannot effectively distribute wash liquid at high temperatures or when encountering obstacles

Engineering Contradiction:

Improvespray arm rotation reliabilityVSAvoidwash liquid distribution efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the hydraulic rotation system with a magnetic drive system. A magnetic coupler positioned adjacent to the spray arm uses magnetic fields to rotate the spray arm directly, eliminating the need for hydraulic pressure-driven rotation. This magnetic drive system maintains reliable rotation even at high temperatures where hydraulic systems fail, and continues to operate effectively when obstacles are present in the wash liquid flow path.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Power

If hydraulic power is used to rotate spray arms, then rotation can be achieved, but power usage increases and effectiveness decreases at high temperatures

Engineering Contradiction:

Improvepower usageVSAvoidoperation effectiveness at high temperature

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The magnetic drive system substitutes hydraulic power transmission with magnetic field interaction. The magnetic coupler generates rotational force through magnetic fields, which is transmitted to the spray arm without requiring high hydraulic pressure. This system maintains operation effectiveness at high temperatures because magnetic fields are not affected by thermal conditions that degrade hydraulic fluid performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If obstacles are present in the wash liquid flow, then hydraulic rotation may fail, but the magnetic system ensures consistent rotation

Engineering Contradiction:

Improverotation consistencyVSAvoidoperation under obstacle conditions

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

By replacing hydraulic rotation with magnetic drive, the system achieves rotation consistency independent of wash liquid flow conditions. The magnetic coupler directly drives the spray arm rotation through magnetic fields, bypassing the need for hydraulic pressure that can be disrupted by obstacles in the liquid flow path.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The magnetic field acts as an intermediary between the power source and the spray arm rotation mechanism. This magnetic intermediary transmits rotational force without requiring direct mechanical or hydraulic connection, allowing the spray arm to rotate consistently even when obstacles block the wash liquid flow that would otherwise drive hydraulic rotation.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 magnetic system enhances cleaning efficiency by ensuring consistent rotation of spray arms, even at high temperatures and when encountering obstacles, while minimizing hydraulic power usage and maintaining effective wash liquid distribution.

Implementation Method 1

A first magnetic coupler is located outside the wash chamber adjacent the lower surface of the column. The first magnetic coupler is coupled to and rotatably driven by the motor. A second magnetic coupler is located in the wash chamber adjacent the upper surface of the column. The second magnetic coupler is coupled to the sprayer and magnetically coupled to and rotatable with the first magnetic coupler such that rotation of the first magnetic coupler rotates the sprayer.

Methodology Applied

Scientific EffectMagnetic coupling: Magnetism

Data Source

PatentUS8240321B2Magnetic drive controlled rotation for dishwasher spray arm

Publication Date: 2012.08.14 WHIRLPOOL CORP

AI summary

A motorized system drives rotation of a rotatable sprayer of a dishwasher. The drive system includes a magnetic coupler. The magnetic coupler includes a first portion that resides inside the wash chamber of the dishwasher, and a second portion that resides outside the wash chamber, such that the motor and the output shaft of the drive system are located entirely outside of the wash chamber.