Appliance Door Locking Using Motor Energy During Power Loss

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Solution Overview

Problem

Existing door-lock systems for household appliances, such as washing machines, face challenges in providing design flexibility and safety while being cost-effective, as they often require large safety margins and complex control electronics due to delays unrelated to physical risk factors, leading to increased design and industrial costs.

Innovation Solution

A door-lock system with a control unit that manages the power supply of motor means to maintain the door closed, using a brushless electric motor, a movable core, and a locking pin mechanism, which allows the system to detect the door's position without expensive sensors, ensuring safety until the appliance's kinetic energy falls below a preset threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a door-lock device uses a bimetal plate and PTC heating element with a preset time delay to ensure safety after power failure, then the door remains locked for a fixed time interval, but the delay is not related to the actual kinetic energy of the moving parts and requires large safety margins and complex control electronics

Engineering Contradiction:
Improvedoor locking safetyVSAvoidcontrol electronics complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the complex thermal-mechanical bimetal system with a purely mechanical kinetic energy-based locking mechanism. The spring-loaded latch automatically engages when the drum's kinetic energy drops below a threshold, eliminating the need for PTC heating elements, bimetal plates, and associated control electronics while maintaining safety through direct physical coupling between drum motion and latch engagement

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

Solution Approach 2:

The door-lock system becomes self-regulating by using the drum's own kinetic energy as the triggering mechanism. The spring-loaded latch automatically engages or disengages based on the drum's motion state without requiring external power or control systems, making the system self-sufficient and eliminating complex control electronics

Inventive Principle:
Principle #25Self-service

2Reliability

If a door-lock device uses expensive sensors and complex control electronics to detect door position and control locking, then the safety and precision are improved, but the manufacturing cost increases significantly

Engineering Contradiction:
Improvedoor position detection accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent eliminates expensive sensors and electronic control systems by using a purely mechanical spring-loaded latch mechanism. The latch's engagement and disengagement are directly controlled by the drum's kinetic energy through mechanical coupling, providing accurate door position detection and locking control through passive mechanical means rather than active electronic sensing

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

Solution Approach 2:

The system uses a simplified mechanical model where the spring-loaded latch replicates the function of expensive electronic sensors and control systems. The mechanical latch directly translates drum kinetic energy into locking action, creating a functional copy of complex electronic control through simple mechanical components that are much cheaper to manufacture

Inventive Principle:
Principle #26Copying

3Adaptability or versatility

If a door-lock system provides design flexibility with multiple locking mechanisms, then the adaptability to different applications is improved, but the device complexity and cost increase

Engineering Contradiction:
Improvedesign flexibilityVSAvoiddoor-lock device complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The spring-loaded latch mechanism serves multiple functions: it locks the door when drum kinetic energy is high, unlocks when kinetic energy drops below threshold, and provides automatic safety interlocking. This single universal mechanism replaces what would traditionally require multiple separate locking devices, providing design flexibility without increasing complexity

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

Solution Approach 2:

The door-lock system uses dynamic characteristics of the spring-loaded latch that automatically adjusts its state based on the drum's kinetic energy. The latch transitions between locked and unlocked states dynamically响应 to the physical motion of the drum, providing adaptability to different operating conditions without requiring complex control systems

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

This solution provides enhanced safety and design flexibility by reducing the need for expensive sensors and complex electronics, allowing the door to remain closed until the appliance's kinetic energy is low enough, thus addressing the limitations of prior systems while minimizing costs.

Implementation Method 1

motor means being capable of powering said control unit when they are moving with no power

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

said door-lock could comprise a movable core, a coil, within which said movable core is placed

Methodology Applied
Scientific EffectElectromagnetic force: Electromagnet

Data Source

PatentEP3172373B1Door-lock system for household appliance provided with such system and operation method thereof
Publication Date: 2018.03.07 BITRON SPA
  • EP3172373B1 patent drawingFigure 1~3
  • EP3172373B1 patent drawingFigure 2a~4b
  • EP3172373B1 patent drawingFigure 5a~6

AI summary

The present invention concerns a door-lock system (1) for a household appliance, such as a washing machine and the like, of the type provided with a door, to which a hook is associated, and a member (C) to be moved of said household appliance, such as a washing drum or the like, said door-lock system (1) comprising motor means (3) for operating said member to be moved (C) and a door- lock device (4), capable of interacting with said hook, to lock said door, wherein said door-lock system (1) comprises a control unit (2), capable of controlling the power supply of said motor means (3) and connected to said door-lock device (4), so as to control the power supply to hold said hook and to close said door, said motor means (3) being capable of powering said control unit (2) when said motor means (3) is moving with no power, and said control unit (2) being configured so that, in case of malfunction of said household appliance or of absence of power, said control unit (2) being fed by said motor means, feeds said door-lock device (4) for holding said door closed, until said member (C) to be moved has a kinetic energy lower than a presettable threshold.