Hall Sensor Door Lock Position Detection With Fault Monitoring

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Solution Overview

Problem

Existing door position detection systems in household appliances, such as reed switches, fail to accurately differentiate between normal operating states and malfunctions, leading to potential safety issues like water splashing due to incorrect circuit interpretations.

Innovation Solution

A door position detection system using a Hall sensor and a permanent magnet, where the magnetic switch provides distinct signals for open and closed door positions, connected to a monitoring circuit for self-diagnostic capabilities and additional safety functions, allowing for continuous functionality checks and triggering safety measures like switching off pumps when the door is not closed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a reed switch is used to detect door lock position, then the door position can be detected, but malfunctions such as short circuit or interruption are interpreted as normal operating states and are not recognized

Engineering Contradiction:
Improvedoor position detection accuracyVSAvoidmalfunction detection capability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements a monitoring circuit that continuously monitors the reed switch signal and provides feedback to detect malfunctions. The monitoring circuit checks for unexpected signal states and can trigger error indications when the reed switch fails, thereby resolving the contradiction between detection capability and reliability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent introduces a monitoring circuit as an intermediary between the reed switch and the control system. This intermediary component evaluates the reed switch signals and distinguishes between legitimate door position changes and malfunction conditions, thereby improving both measurement precision and reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a monitoring circuit is added to detect malfunctions, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improvemalfunction detection capabilityVSAvoidcircuit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the monitoring circuit functions with the existing door position detection circuitry. By merging the monitoring capabilities into the existing control system rather than adding completely separate monitoring hardware, the patent improves reliability while minimizing the increase in device complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If the door lock mechanism is made more secure to prevent opening during operation, then safety is improved, but ease of operation decreases

Engineering Contradiction:
Improvedoor security during operationVSAvoiddoor opening ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent implements a dynamic door lock mechanism that adjusts its locking strength based on operational state. During appliance operation, the lock engages firmly to prevent accidental opening. During loading/unloading phases, the lock mechanism allows easier door opening. This dynamic behavior resolves the contradiction between security and ease of operation.

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

Ensures accurate door position detection, provides a self-diagnostic capability, and integrates an additional safety function by generating signals that indicate door position and circuit functionality, preventing accidents like water splashing during appliance operation.

Implementation Method 1

the door position detection means have at least one permanent magnet and one magnetic switch, so that the device has a simple structure. According to the invention it is provided that the magnetic switch is a Hall sensor.

Methodology Applied
Scientific EffectHall effect: Hall Effect

Data Source

PatentEP2166915B1Domestic appliance with a self-diagnosing door lock position detection device
Publication Date: 2012.10.31 BSH HAUSGERATE GMBH
  • EP2166915B1 patent drawingFigure 1
  • EP2166915B1 patent drawingFigure 2

AI summary

The invention relates to a domestic appliance (10) having a door (14) which can be arrested by means of a locking device (18), and having a door lock position detection device (64) which has at least one permanent magnet (34) and a magnetic switch which can be moved to the active range of the permanent magnet (34) by movement of the door (14). The invention provides for the magnetic switch to be a Hall sensor (36). The invention also covers a door lock position detection device (64).