Electromagnetic door lock
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Solution Overview
Problem
Existing electromagnetic door locks for domestic appliances, such as washing machines, suffer from bouncing and wear of switch components, leading to malfunction of electronic control units due to increased electrical resistance and potential damage from electric arcs.
Innovation Solution
The implementation of contactless proximity sensors, like magnetic sensors or magnetoresistive sensors, replace traditional electromechanical switches, ensuring reliable door sensing without mechanical contact, using a rotating cam and locking pin mechanism with electromagnetic actuation and sensors to detect door and locking positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional electromechanical switches with metal contact strips and rivets are used, then the door lock can perform switching function, but switch components experience bouncing and wear leading to increased electrical resistance and control unit malfunction
Solution Approach 1:
The patent replaces the mechanical electromechanical switch system with a magnetic sensing system. The door sensing pin with magnet interacts with a Hall effect sensor or magnetoresistive sensor, eliminating all mechanical contact components. This substitution removes the sources of bouncing and wear, providing contactless detection of door position while maintaining reliable switching signals for the control unit.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the door sensing pin and the sensor. The magnet on the sensing pin generates a magnetic field that the Hall effect or magnetoresistive sensor detects, allowing information transfer about door position without physical contact. This intermediary approach enables reliable sensing while eliminating mechanical wear and bouncing issues.
2Reliability
If metal contact components are used in the switch, then electrical connection is achieved, but electric arcs can occur causing contact surface damage and increased contact resistance
Solution Approach 1:
The patent replaces the electrical contact-based switching system with a magnetic field-based sensing system. The Hall effect sensor or magnetoresistive sensor detects the magnetic field from the door sensing pin's magnet and generates switching signals without any electrical contact between moving and stationary components. This eliminates the conditions necessary for electric arc formation while maintaining reliable electrical signal output to the control unit.
3Ease of operation
If electromechanical switches are used, then door position sensing is achieved, but switch bouncing causes control unit malfunction
Solution Approach 1:
The patent replaces the mechanical switch mechanism with a magnetic sensing mechanism. The Hall effect sensor or magnetoresistive sensor continuously monitors the magnetic field position of the door sensing pin, providing smooth, bounce-free transition signals to the control unit. This contactless detection method eliminates the bouncing phenomenon inherent in mechanical switches, ensuring reliable control unit operation.
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 reduces switch bouncing and wear, enhancing the reliability and longevity of the door lock system by eliminating contact-related issues and preventing electronic control unit malfunctions, ensuring accurate door locking and sensing without interference from external magnetic fields.
Implementation Method 1
a magnetic sensor which detects a magnetic field generated by a magnet mounted on the door sensing pin
Implementation Method 2
magnetic sensor which detects a magnetic field
Implementation Method 3
magnetoresistive sensor which detects a magnetic field generated by a magnet
Implementation Method 4
electromagnetic actuator which actuates the locking pin between locked and unlocked positions
Data Source
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AI summary
An electromagnetic door lock for locking the door of a domestic appliance, comprising: - rotating cam (12) rotating about, an axis (A) between an open-door position and closed-door position and cooperating with a nook (14) fixed to a door of a domestic appliance; - a locking device (16) which locks the rotating cam (12) in the locking position, the locking device (16) including an electromagnetic actuator (24) configured for moving a locking pin (30) between a locking position and an unlocking position; - a door sensing device (34) including a door sensing element (35) movable between a first position and a second position corresponding, respectively, to the open-door position and to the closed-door position of the rotating cam (12 ); and - at least one contactless proximity sensor (44) which detects said locking position of the locking pin (30).