Shape-Memory Alloy Door Lock to Reduce Appliance Energy Consumption

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Solution Overview

Problem

Current door locking devices for electric household appliances consume high electricity due to positive temperature coefficient components and are complex and expensive to produce, with slow release times.

Innovation Solution

A door locking device using a shape-memory alloy resistance wire to control the latch mechanism, eliminating electronic components and reducing power consumption, featuring a latch and traction pin system with elastic thrust means for efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If positive temperature coefficient components are used in the door locking device, then the locking function is reliable, but the electric consumption increases significantly

Engineering Contradiction:
Improvelocking function reliabilityVSAvoidelectric consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent removes the PTC (positive temperature coefficient) components from the door locking device structure. By extracting these energy-consuming components, the invention eliminates the continuous power consumption problem while maintaining the locking function through a purely mechanical spring-based system that only requires brief actuator activation.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The spring-based locking mechanism is designed to be self-sustaining once activated. The spring automatically maintains the locked state without requiring continuous power supply, and the system self-regulates the locking and unlocking cycles through mechanical energy storage and release, eliminating the need for energy-intensive electronic control components.

Inventive Principle:
Principle #25Self-service

2Reliability

If PTC components are used for safety control, then the safety function is ensured, but the release time becomes slow due to cooling requirements

Engineering Contradiction:
Improvesafety functionVSAvoidrelease time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the electronic PTC-based safety control system with a mechanical spring-based safety mechanism. This substitution eliminates the thermal inertia and cooling time associated with PTC components, allowing the door to be released immediately when the actuator retracts, as the mechanical spring responds instantaneously to position changes.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If electronic control components are used in the door locking device, then the control precision is improved, but the device complexity and production cost increase

Engineering Contradiction:
Improvecontrol precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention extracts and removes electronic control components from the door locking device, retaining only the essential mechanical elements (spring, latch, actuator). This simplification reduces device complexity and production costs while maintaining adequate control precision through mechanical positioning and engagement features.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs simple, inexpensive mechanical components that can be easily manufactured and replaced. The spring-based mechanism uses basic mechanical parts rather than expensive electronic components, reducing both initial production costs and long-term maintenance expenses.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 solution results in a simpler, cheaper, and more energy-efficient door locking system with faster release times, reducing overall energy consumption and production costs.

Implementation Method 1

said latch means comprising: a latch hinged to the box body to at least rotate, about a first axis, between said lock position locking said door, and in which the latch engages a catch on said door to hold the door in the closed position

Methodology Applied
Scientific EffectShape memory alloy: Shape Memory Alloy

Implementation Method 2

electric power means for powering said resistance wire and producing a controlled Joule effect variation in temperature

Methodology Applied
Scientific EffectJoule effect: Joule Heating

Implementation Method 3

elastic thrust means connected to the carriage to move it in the forward direction when the resistance wire increases in length

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2518243B1Electric household appliance comprising a door locking device
Publication Date: 2019.06.12 ELECTROLUX HOME PROD CORP NV
  • EP2518243B1 patent drawingFigure 1
  • EP2518243B1 patent drawingFigure 2
  • EP2518243B1 patent drawingFigure 3

AI summary

An electric household appliance having a casing (2); a compartment (3) housed inside the casing (2) and facing an opening (4); a door (5) fitted to the casing (2) and movable between an open position and a closed position; and a locking device (6); the locking device (6) having a box body (7) fixed to the casing (2), alongside the door (5); latch means (8, 13) fitted to the box body (7) to move between a lock position locking the door (5), and a release position releasing the door (5); and an actuating device (11) for selectively moving the latch means (8, 13) between the lock position and the release position, and which has at least an electrically conducting resistance wire (16) made of a shape-memory alloy and designed to vary in length alongside a variation in temperature, and electric power devices (18) for powering the resistance wire (16) and producing a controlled Joule-effect variation in temperature.