Dual-Contact Door Interlock for Washer Lock State Detection
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Solution Overview
Problem
Existing door interlock mechanisms for washing machines and tumble dryers fail to reliably prevent machine operation with the door open and cannot accurately detect incorrect blocking of the closing device, leading to safety concerns and operational issues.
Innovation Solution
A door interlock mechanism with two independent contacts, a locked-door contact and an open-door contact, that uses a combination of electromechanical components and spring-actuated sliders to ensure the door is properly closed and locked, and detects abnormal situations such as accidental detachment or incorrect blocking, by controlling the machine's operating circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single contact system is used to detect door position, then the device complexity is reduced, but the reliability of detecting abnormal situations deteriorates
Solution Approach 1:
The door position detection function is segmented into two independent contacts: a first contact that detects when the door is closed, and a second contact that detects when the door is properly locked. This segmentation allows each contact to perform a specific detection function, improving overall reliability without requiring a single complex detection system.
Solution Approach 2:
The control unit acts as an intermediary that receives signals from both contacts and processes them to determine the actual door state. By comparing the states of both contacts, the control unit can detect abnormal situations such as when the door appears closed but is not properly locked, providing reliable detection while maintaining simple contact structures.
2Reliability
If mechanical locking alone is used to prevent door opening, then the ease of operation is improved, but the ability to detect and respond to abnormal situations deteriorates
Solution Approach 1:
The system implements feedback by continuously monitoring the door position through the two contacts and providing real-time information to the control unit. The control unit can detect when the door is closed but not properly locked, and can respond by preventing machine operation or generating alerts, thereby maintaining safety without complicating the physical door operation.
Solution Approach 2:
The patent replaces pure mechanical interlocking with an electromechanical system where electrical contacts provide feedback to a control unit. This substitution allows for more sophisticated detection and response capabilities while maintaining the simplicity of the mechanical door locking mechanism itself.
3Strength
If the door catch is made more robust to prevent accidental detachment, then the strength is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The door catch is designed with a resilient portion that provides dynamic response to forces applied during normal operation. This resilient element absorbs shocks and variations in force without requiring the catch to be overly robust, maintaining manufacturing simplicity while ensuring reliable engagement during the washing cycle.
Solution Approach 2:
The resilient portion of the door catch acts as a cushioning element that anticipates and absorbs potential impacts or misalignments during door closing. This beforehand cushioning prevents accidental detachment without requiring the catch to be manufactured with excessive strength or complexity.
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 machine operation with the door open and accurately detects incorrect blocking, ensuring safe and reliable operation by reliably controlling the machine's operating circuit and stopping the cycle when abnormal conditions are detected.
Implementation Method 1
a resilient portion, which has the function of deforming under the action of a force in order to engage or disengage from the blocking device
Implementation Method 2
a solenoid, having the function of actuating the interlock latch
Implementation Method 3
a latch actuated by a thermal system
Data Source
Figure 1
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Figure 4
AI summary
In door interlock mechanisms, used for locking the door of washing machines or tumble dryers, the closed or open state of the door of the machine is detected by reading the resistive value of a circuit in which a switch is placed in series. The interlock mechanism according to the invention envisages providing the door interlock with two contacts that make it possible to check, independently, whether the device is in the position with the door closed and locked and whether the door catch is inserted in the device. The device comprises an open-door contact (15), actuated in the closing position by a shaped portion (12) of a first slider (7) and in the opening position by a shaped portion (14) of a second slider (8) which, under the action of elastic means (10), interacts with the door catch (19).