Door Lock Drive Mechanism With Magnetic Blocker Against Shaft Manipulation
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Solution Overview
Problem
Existing door lock mechanisms are vulnerable to manipulation by external magnets, which can rotate the shaft and unlock the door without authorization, despite countermeasures like C-shaped brackets and magnet blockers.
Innovation Solution
A magnet blocker with a specific configuration that moves from a neutral to an engagement position, establishing a form- and/or force-fit with the shaft, preventing rotation induced by external magnets, using a ferromagnetic disk with arms that interact with the shaft's surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnet blocker is provided to prevent shaft rotation by external magnets, then security against manipulation is improved, but the device complexity increases
Solution Approach 1:
The magnet blocker is designed as a hollow cylindrical component that surrounds the shaft, with the shaft passing through its central opening. This nested configuration allows the magnet blocker to engage with the shaft's outer circumferential surface while maintaining a compact structure. The blocker's inner circumferential surface forms a form-fit connection with the shaft, preventing rotation without requiring additional external components or complex mechanisms.
Solution Approach 2:
The magnet blocker is divided into distinct functional zones: an inner circumferential surface for form-fit engagement with the shaft, an outer circumferential surface for interaction with external magnets, and a hollow interior space. This segmentation allows each surface to perform its specific function independently - the inner surface prevents rotation through geometric interference, while the outer surface responds to magnetic fields, thereby enhancing security with minimal added complexity.
2Reliability
If the magnet blocker engages the shaft to prevent rotation, then security is improved, but the ease of operation deteriorates due to potential interference with normal shaft movement
Solution Approach 1:
The magnet blocker is designed with movable mounting elements that allow it to shift radially outward when the shaft rotates during normal operation. This dynamic behavior enables the blocker to disengage from the shaft's outer circumferential surface during legitimate use, preventing interference with normal door locking and unlocking operations. The blocker only engages to prevent rotation when external magnetic forces attempt to manipulate the shaft, thereby maintaining ease of operation while enhancing security.
Solution Approach 2:
The engagement between the magnet blocker and shaft is localized to specific regions rather than being continuous. The inner circumferential surface of the blocker contacts only the outer circumferential surface of the shaft at discrete points, creating a form-fit connection that prevents rotation but allows for controlled movement during normal operation. This localized engagement ensures security against manipulation while minimizing interference with legitimate shaft rotation.
3Reliability
If a form-fit connection is established between the magnet blocker and shaft, then prevention of shaft rotation is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The magnet blocker and shaft feature asymmetric geometric profiles on their interacting surfaces. The inner circumferential surface of the blocker has a specific asymmetric shape that complements the asymmetric outer circumferential surface of the shaft, creating a form-fit connection that prevents rotation. This asymmetric design provides robust rotational prevention through geometric interference rather than relying on tight tolerances, thereby reducing manufacturing precision requirements while maintaining effective security.
Solution Approach 2:
The form-fit connection between the magnet blocker and shaft is designed to engage automatically during assembly without requiring precise alignment procedures. The geometric profiles are configured so that the blocker naturally seats onto the shaft in the correct orientation, establishing the rotational prevention mechanism in advance. This preliminary engagement eliminates the need for post-assembly adjustments or high-precision alignment, reducing manufacturing complexity while ensuring reliable security.
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 the rotation of the shaft when an external magnet is moved around it, enhancing security by ensuring the door lock cannot be actuated unauthorizedly.
Implementation Method 1
a rotation of the shaft due to induction of a magnetic force in the stator, when the external magnet is moved around the shaft in the circumferential direction
Implementation Method 2
using a ferromagnetic disk with arms that interact with the shaft's surface
Data Source
Figure 1
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AI summary
The present invention provides a door lock drive mechanism comprising an electromotor (2) having a stator, a shaft (4), which is adapted to be rotated by energization of the stator, and a magnet blocker (16) having a through-hole (17), through which the shaft (4) extends such that the magnet blocker (16) surrounds the shaft (4) in its entire circumferential direction, such that the through-hole (17) in a neutral position, is coaxial to the shaft (4) and not in contact with an outer circumferential surface of the shaft (4), the through-hole (17) defines an inner circumferential surface of the magnet blocker (16) and the magnet blocker (16) comprises a material which can be attracted by an external magnet (15). In order to counteract the manipulation of a door lock drive mechanism with an external magnet, the magnet blocker (16) is adapted in that upon bringing the external magnet (15) from a direction perpendicular to an extension direction of the shaft (4) in a vicinity of the magnet blocker (16), the magnet blocker is moved from its neutral position into an engagement position with the shaft (4), such that the inner circumferential surface of the magnet blocker (16) comes into contact with the outer circumferential surface of the shaft (4), such that a form- and/or force-fit is provided therebetween, such that a rotation of the shaft (4) due to induction of a magnetic force in the stator, when the external magnet (15) is moved around the shaft (4) in the circumferential direction, is prevented. Further, it is provided a method for updating a door lock drive mechanism.