Lock Cylinder Blocking Members Prevent Unauthorized Rotation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lock cylinders are vulnerable to unauthorized access through the use of bump keys and pick tools, which can align pins to rotate the lock cylinder without the proper key, necessitating a solution to prevent such unauthorized access.

Innovation Solution

A plug assembly with blocking members that are initially positioned out of the keyway but radially displace into it when the plug body is rotated, obstructing the keyway and preventing unauthorized access by engaging with the inner surface of the plug housing, and a key with receptacles to receive these blocking members, allowing authorized access while jamming unauthorized tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional pin alignment mechanisms are used, then the lock can be opened with a key, but unauthorized access through bump keys and pick tools is possible

Engineering Contradiction:

Improvelock securityVSAvoidkey operation

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

Blocking members are pre-positioned in slots within the plug body, ready to radially displace into the keyway upon rotation. This preliminary positioning ensures that as soon as unauthorized rotation begins, the blocking members are immediately available to obstruct the keyway and jam the tool, preventing further unauthorized operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The blocking members are designed to proactively counteract unauthorized rotation attempts before they can succeed. When the plug body rotates relative to the housing, the blocking members radially displace into the keyway path, creating immediate resistance and jamming effect that prevents bump keys and pick tools from achieving pin alignment and defeating the lock

Inventive Principle:

Principle #9Preliminary anti-action

2Reliability

If blocking members are added to prevent unauthorized access, then security against pick tools is improved, but the device complexity increases

Engineering Contradiction:

Improveprotection against lock pickingVSAvoidplug assembly structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The blocking members are integrated within the plug body structure itself, with each blocking member housed in a slot that is part of the plug body. The cam portions of the blocking members engage with the housing inner surface, merging the blocking function into the existing plug-housing rotation mechanism rather than adding separate independent components

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The blocking members serve multiple functions: they obstruct the keyway to prevent unauthorized access, jam pick tools and bump keys, and their cam portions engage with the housing to enable controlled rotation when proper key receptacles are present. This multi-functionality reduces the need for separate components

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If blocking members radially displace into the keyway during rotation, then unauthorized tools are jammed and access is prevented, but the force required to rotate the plug increases

Engineering Contradiction:

Improveprevention of unauthorized rotationVSAvoidrotation force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The blocking members are positioned at specific locations within the keyway path, providing localized obstruction only where needed to jam unauthorized tools. The cam portions engage with the housing at specific engagement points, concentrating the force interaction at precise locations rather than distributing resistance throughout the entire plug structure

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The blocking members dynamically transition between retracted and extended positions based on plug rotation. During authorized key operation, the blocking members radially displace into the keyway to provide obstruction. When the key is removed and unauthorized rotation is attempted, the blocking members are positioned to jam the tool, creating variable force requirements that adapt to the operational state

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9447605B1Key and lock cylinder

Publication Date: 2016.09.20 SCHLAGE LOCK CO LLC

AI summary

A plug assembly for a lock includes a generally cylindrical plug body that defines a keyway and a generally cylindrical plug housing that rotatably receives the plug body. A plurality of blocking members are housed in the plug body and are movable into the keyway upon rotation of the plug body relative to the plug housing to obstruct the keyway. A key can be provided that is positionable into the keyway, and the blade of the key defines receptacles for receiving the blocking members when the plug body is rotated so that the lock can be unlocked. However, the blocking members prevent rotation of the plug body when a picking tool or unauthorized key is inserted in the keyway since either the blocking members cannot move into the keyway and remain engaged to the plug housing due to the object in the keyway, or obstruct the keyway and prevent insertion of the picking tool.