Door Interlock Wheel Detection for Washer Start Inhibition

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Solution Overview

Problem

Existing interlock devices for household appliances, such as washing machines, fail to prevent the appliance from starting when the door is open due to incorrect blocking or disassembly of the interlock wheel, leading to safety hazards and inability to lock the door properly.

Innovation Solution

The interlock device includes a first slider with a locking pin and groove to detect disassembly conditions of the interlock wheel and prevent the closure of the operating circuit, ensuring the appliance cannot be switched on if the interlock wheel is disassembled, using a locking pin and arrest element to hamper the movement of the interlock latch.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of repair

If the interlock wheel is made disassemblable for maintenance purposes, then ease of repair is improved, but reliability deteriorates because the appliance can be switched on even when the door is not properly locked

Engineering Contradiction:
Improveease of repairVSAvoidreliability
Core Design Contradiction:
Ease of repairVSReliability

Solution Approach 1:

The patent introduces an intermediary detection system consisting of a first slider with a locking pin and groove that detects whether the interlock wheel is properly assembled. The locking pin engages with a corresponding element on the interlock wheel, and the groove detects the presence of this engagement. This intermediary detection mechanism prevents the appliance from being switched on when the interlock wheel is disassembled, thereby maintaining reliability while allowing the interlock wheel to be disassembled for maintenance.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If the interlock device uses a simple mechanical structure, then device complexity is reduced, but reliability deteriorates because it cannot detect disassembly conditions of the interlock wheel

Engineering Contradiction:
Improvedevice complexityVSAvoidreliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent segments the detection function into separate components: a first slider with a locking pin for detecting interlock wheel assembly status, a second slider for detecting door catch insertion, and the interlock wheel itself. This segmentation allows each component to have a specific, simple function while collectively providing comprehensive reliability monitoring. The locking pin and groove configuration adds minimal complexity but enables critical disassembly detection.

Inventive Principle:
Principle #1Segmentation

3Ease of operation

If the door catch is made to engage easily with the interlock wheel, then ease of operation is improved, but reliability deteriorates because incorrect blocking or disassembly cannot be detected

Engineering Contradiction:
Improveease of operationVSAvoidreliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the first slider with the locking pin continuously monitors the engagement status of the interlock wheel. When the door catch engages with the interlock wheel, the locking pin detects this through its groove configuration. This feedback is transmitted to the control circuit, which prevents the appliance from being switched on unless proper engagement is detected. This maintains ease of operation while ensuring reliability through automatic verification.

Inventive Principle:
Principle #23Feedback

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

Effectively prevents the appliance from starting when the interlock wheel is disassembled, ensuring the door remains locked and safe, thereby preventing accidents and ensuring proper operation.

Implementation Method 1

a catch or interlock wheel (6), able to rotate to correspond to opening (5) and subject to the action of a torsional spring (17)

Methodology Applied
Scientific EffectTorsional spring: Torsion Spring

Implementation Method 2

Two sliders (7 and 8) are housed in the support (1) and, subject respectively to the action of coil springs (9 and 10), engage the interlock wheel (6) with their shaped ends

Methodology Applied
Scientific EffectElastic force: Spring

Data Source

PatentEP3037579B1Interlock device for the closing door of household appliances
Publication Date: 2018.03.28 ELETTROTECNICA ROLD
  • EP3037579B1 patent drawingFigure 1
  • EP3037579B1 patent drawingFigure 2
  • EP3037579B1 patent drawingFigure 3

AI summary

The present invention relates to an interlock device for the closing door of household appliances, particularly for washing machines and/or tumble dryers, of the kind suitable to detect closed and locked condition of the door, suitable to detect a condition of disassembling of the cover which contains and retains the interlock wheel for retaining the door catch and to avoid the possibility that the appliance to which it is associated is switched on in case of disassembling of the interlock wheel.