Tamper-Proof Door Lock Mechanism with Auxiliary Latch Blocking

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Solution Overview

Problem

Existing door and window locks with pivoted latches and auxiliary latch devices lack effective protection against manipulation, leading to accidental extension of the locking bar when the auxiliary latch is actuated, preventing door closure and potentially causing damage.

Innovation Solution

A lock mechanism with a locking device featuring a spring-loaded latch and auxiliary latch, where the locking bar is controlled by an auxiliary latch and a switching element, ensuring the locking bar remains blocked when open and is released only when the latch is actuated and the auxiliary latch is canceled, preventing accidental extension and damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pivotally mounted latch with auxiliary latch mechanism is used, then the locking function is achieved, but the tamper resistance is low and accidental extension can occur

Engineering Contradiction:
Improvelocking functionVSAvoidmanipulation vulnerability
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A control element is introduced as an intermediary between the auxiliary latch and the locking bar. The control element receives the actuating force from the auxiliary latch and transmits it to the locking bar, while being subject to counteracting forces from blocking elements. This intermediary mechanism prevents direct coupling that would allow accidental extension, as the control element must overcome the blocking elements' resistance before the locking bar can extend.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

Blocking elements are positioned to preemptively oppose the extension of the locking bar. These blocking elements create preliminary resistance that must be overcome before the locking bar can extend, even when the auxiliary latch is actuated. This preliminary anti-action prevents accidental or unauthorized extension by requiring intentional overcoming of the blocking mechanism.

Inventive Principle:
Principle #9Preliminary anti-action

2Ease of operation

If the auxiliary latch is directly coupled to the locking bar, then actuation is simple, but accidental extension occurs when the door is open

Engineering Contradiction:
Improvelatch actuationVSAvoidaccidental extension prevention
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The control element serves as a mediator between the auxiliary latch and the locking bar, decoupling their direct interaction. When the auxiliary latch is actuated, the control element is subjected to forces that must overcome the blocking elements before transmitting motion to the locking bar. This indirect coupling maintains operational simplicity while preventing accidental extension when the door is open.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system transitions from a static direct coupling to a dynamic indirect coupling where the control element can move independently relative to both the auxiliary latch and the locking bar. The control element's position and the engagement state of the blocking elements dynamically determine whether actuation of the auxiliary latch results in extension of the locking bar, allowing the system to differentiate between intentional and accidental actuation.

Inventive Principle:
Principle #15Dynamics

3Object-affected harmful factors

If blocking elements are added to prevent accidental extension, then tamper resistance improves, but the device complexity increases

Engineering Contradiction:
Improvemanipulation protectionVSAvoidlocking mechanism structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The blocking elements are merged with the control element or the auxiliary latch mechanism, such that the blocking function is integrated into the existing structure rather than being a separate independent component. This integration reduces overall device complexity while maintaining the tamper resistance benefits of having blocking elements that prevent accidental locking bar extension.

Inventive Principle:
Principle #5Merging (Combining)

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

Enhances security by ensuring the locking bar remains blocked when the door is open and is only released when intended, preventing accidental extension and damage during closure, thus improving manipulation protection.

Implementation Method 1

a preferably spring-mounted latch, which has an entry ramp and/or an exit ramp and is designed such that the latch can be engaged in a frame-mounted strike plate in a locking position

Methodology Applied
Scientific EffectSpring force: Spring

Data Source

PatentEP3122968B1Switch lock with tamper-proofing for preventing an auxiliary latch actuation
Publication Date: 2019.04.24 ASSA ABLOY SICHERHEITSTECHNIK GMBH
  • EP3122968B1 patent drawingFigure 1
  • EP3122968B1 patent drawingFigure 2
  • EP3122968B1 patent drawingFigure 3

AI summary

The invention relates to a lock with a lock mechanism comprising a locking device (6, 7) and an actuation device (8, 8d). The locking device (6, 7) has at least one locking rod which can be actuated by the actuation device (8, 8d), and the locking device (6, 7) has a preferably spring-mounted latch (11). The at least one locking rod (7, 17) and the latch (11) are designed to be movable relative to each other, and the at least one locking rod (7, 17) interacts directly or indirectly with the latch (11) in order to control the latch (11). The locking device (7) has an auxiliary latching device (12) in the region of the latch (11), said auxiliary latching device being controllable via the striker plate 4s or a striker plate-side part and interacting with the locking rod (7, 17) in order to block or release the locking rod (7, 17). In the process, the locking rod (7, 17) interacts with the latch (11) and the auxiliary latch (12) such that a) when the auxiliary latch (12) is actuated and the latch (11) is not actuated, the locking rod (7, 17) is blocked and is not released, b) when the auxiliary latch (12) and the latch (11) are actuated at the same time, the locking rod (7, 17) is blocked and is not released, and c) by subsequently withdrawing the latch (11) while the auxiliary latch (12) remains actuated when the auxiliary latch (12) and the latch (11) are actuated at the same time, the locking rod (7, 17) is unblocked, thereby releasing the locking rod.