Door-lock with a hook detection slider with additional security

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Solution Overview

Problem

Existing door-lock systems for household appliances continue to send electrical pulses to the electromagnetic actuator and provide incorrect closed door signals during abnormal conditions, leading to noise and heating issues.

Innovation Solution

The door-lock system incorporates a safety feature with a bistable spring mechanism and a safety portion on the hook sensing slider that prevents the door sensing slider from moving to the closed position when the cam support's integrity is compromised, ensuring the door detection circuit remains open and no electrical pulses are sent to the actuator in abnormal conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the locking slider is allowed to move freely to detect door position, then the door detection circuit can provide accurate open/closed door information, but in abnormal conditions the locking slider may move incorrectly and provide false closed door signals

Engineering Contradiction:
Improvedoor position detection accuracyVSAvoiddoor detection reliability in abnormal conditions
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The safety portion acts as an intermediary mechanical element between the locking slider and the cam support. It transfers the integrity verification function from the locking slider alone to the combined system of locking slider + safety portion + cam support, preventing false detection by requiring all three components to be properly aligned and engaged.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The safety portion provides mechanical feedback about the cam support's integrity to the locking slider's detection mechanism. When the cam support is compromised, the safety portion's position changes, which is detected by the door detection circuit, providing feedback that prevents false closed door signals.

Inventive Principle:
Principle #23Feedback

2Ease of operation

If the electromagnetic actuator receives continuous electrical pulses, then the locking mechanism can be actuated, but in abnormal conditions this generates noise and heating issues

Engineering Contradiction:
Improvelocking mechanism actuationVSAvoidnoise and heating from actuator
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The door detection circuit uses feedback from the safety portion's position to control whether electrical pulses are sent to the electromagnetic actuator. In abnormal conditions, the feedback indicates the safety portion is misaligned, so the control unit suppresses pulse generation, eliminating noise and heating while allowing normal operation when aligned.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The invention extracts the abnormal condition detection function from the main locking mechanism by adding the separate safety portion and its alignment detection system. This allows the system to identify and isolate abnormal conditions, preventing the electromagnetic actuator from being activated when it would cause harmful effects.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If a safety verification mechanism is added to prevent abnormal operation, then reliability in abnormal conditions improves, but the device complexity increases

Engineering Contradiction:
Improvedoor-lock reliability in abnormal conditionsVSAvoiddoor-lock structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The safety verification function is merged with the existing door detection circuit rather than being implemented as a separate complex system. The safety portion's alignment detection integrates with the door sensing mechanism, allowing the same circuit to perform both door position detection and safety verification, thus improving reliability without proportionally increasing complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The door detection circuit is given multi-functionality by making it responsible for both detecting door position and verifying the safety portion's alignment with the cam support. This universal approach allows one component to perform multiple functions, improving reliability while minimizing the increase in device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

This solution effectively prevents the door-lock from engaging in abnormal situations, avoiding noise and heating issues by maintaining the door detection circuit in an open state, thus preventing appliance activation and ensuring safety.

Implementation Method 1

a bistable spring mechanism and a safety portion on the hook sensing slider

Methodology Applied
Scientific EffectBistable spring mechanism: Spring

Data Source

PatentEP3541984B1Door-lock with a hook detection slider with additional security
Publication Date: 2022.09.07 ILLINOIS TOOL WORKS INC
  • EP3541984B1 patent drawingFigure 1
  • EP3541984B1 patent drawingFigure 2
  • EP3541984B1 patent drawingFigure 3

AI summary

A door-lock for household appliances, comprising a casing (12) having an opening (14) for the insertion of a hook (15) carried by a door of a household appliance, a cam (16) rotatable between a retaining position and a release position, a locking slider (20) cooperating with said cam (16) and movable between an unlocking position and a locking position, wherein in the locking position the locking slider (20) locks the cam (16) in the retaining position, an electro-magnetic device comprising a housing (70) and a locking pin (28) for locking the locking slider (20) in the locking position, a door sensing slider (32) movable between an open door position and a closed door position, and a hook sensing slider (74) movable between an extracted position and a retracted position, wherein the hook sensing slider (74) has a projection (82) that prevents the movement of the door sensing slider (32) from the open door position towards the closed door position when the hook sensing slider (74) is in the extracted position, wherein the hook sensing slider (74) has a safety portion (86) that, in an abnormal condition in which the integrity of the cam support (11) is compromised, comes into contact with a side (94) of the housing (70) and prevents movement of the hook sensing slider (74) from the extracted position towards the retracted position.