Washing Machine Door Lock Switch Layout for Clean Door Signals
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Solution Overview
Problem
Existing electromagnetic door locking devices for washing machines suffer from signal disturbances due to contact bounce, which can prevent the machine from starting correctly when the porthole door is open, and lack distinct switching behaviors between blocking and non-activated states.
Innovation Solution
A door locking device featuring a contact strip with two parallel, mechanically separate arms to prevent electrical interference, and a design where the differential between closing and opening points of the open-closed door switch is adjusted to ensure a clean signal and prevent incorrect opening, using a solenoid with low traction force to provide a large lifting force for the pawl blocking mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single contact strip is used for detecting door position, then the device structure is simple, but electrical interference between contacts causes signal disturbances
Solution Approach 1:
The contact strip is divided into two separate parallel arms (first arm and second arm) that are mechanically independent. This segmentation prevents electrical interference between contacts because each arm operates independently, eliminating the signal disturbances caused by contact bounce in single-strip designs.
2Force
If the solenoid has high traction force, then the pawl blocking mechanism is effectively actuated, but the manufacturing cost increases
Solution Approach 1:
The device utilizes dynamic positioning of the contact strip arms to create mechanical advantage. When the door moves from closed to open position, the differential between closing and opening points creates a leveraged motion that amplifies the solenoid's traction force, allowing a low-cost solenoid to generate sufficient lifting force on the pawl.
Solution Approach 2:
The invention changes the geometric parameters of the contact strip, specifically the differential between closing and opening points. This parameter optimization allows the system to achieve high mechanical force output from a low-traction solenoid, reducing manufacturing costs while maintaining effective pawl actuation.
3Speed
If the differential between closing and opening points is small, then the switching response is fast, but incorrect traction on the door can cause false opening signals
Solution Approach 1:
The invention optimizes the differential between closing and opening points of the contact strip to specific ranges. This parameter tuning ensures that the switching response is sufficiently fast while creating a mechanical buffer that prevents false opening signals even when incorrect traction is applied to the door.
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 effectively prevents machine start-up when the porthole door is open, reduces signal disturbances, and ensures reliable switching behaviors, while reducing manufacturing costs by using a solenoid with low traction force.
Implementation Method 1
The means for locking the hook interacts with a safety device, known as 'door lock device', the function of which is both to prevent the porthole opening after the machine has been started and to delay its opening under given conditions
Data Source
AI summary
An electromagnetic door locking device for a washing machine and similar, adapted to lock a sliding cursor (30) cooperating with the end of a hook mounted on the machine porthole door through a blocking pawl (12). The device comprises two preloaded parallel and mechanically separate metal strips (16, 17), accomplishing the closing and the opening of the power circuit and of the open/closed door circuit, respectively, and that are maintained in the open position by said pawl (12) and by an actuator (13) operated by said cursor (30), when said door is open. (FIG. 1).