Spring-Loaded Key Coding Element for Drill-Resistant Lock Cylinders

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Solution Overview

Problem

Existing locking devices are vulnerable to drilling attacks due to lack of effective drill protection mechanisms, and there is a need for enhanced security and tactile feedback during key insertion and removal.

Innovation Solution

The locking cylinder incorporates drill protection elements spaced to obstruct the coding element's head, requiring increased force for insertion and providing tactile resistance, combined with spring-loaded heads that move between active and passing positions to interact with locking elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If drill protection elements are added to the locking cylinder, then security against drilling attacks is improved, but device complexity increases

Engineering Contradiction:
Improvesecurity against drilling attacksVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking cylinder is segmented into multiple functional components: the cylinder core, multiple drill protection elements positioned at different locations, and coding elements. This segmentation allows each component to perform its specific function independently, providing comprehensive drill protection without requiring a complete redesign of the entire locking mechanism.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The locking cylinder employs composite construction by combining the cylinder core (typically metal) with drill protection elements made of hard materials. This composite approach creates a multi-layered defense system where the hard drill protection elements resist drilling attacks while the cylinder core provides the primary locking function, achieving enhanced security without significantly increasing overall device complexity.

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If the head of the coding element is spring-loaded to move between active and passing positions, then tactile feedback during key operation is improved, but device complexity increases

Engineering Contradiction:
Improvetactile feedback during key operationVSAvoiddevice complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The head of the coding element is designed as a dynamic component that can move between different positions (active and passing) in response to key insertion. The spring-loaded mechanism allows the head to dynamically adjust its position based on the presence and depth of the key, providing tactile feedback to the user while maintaining a relatively simple overall structure.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The spring-loaded head is a self-regulating mechanism that automatically moves to the appropriate position based on the key insertion depth. The spring force provides the restoring force that returns the head to its default position, eliminating the need for additional actuators or complex control mechanisms while still delivering tactile feedback during operation.

Inventive Principle:
Principle #25Self-service

3Reliability

If the distance between drill protection elements is reduced to obstruct the coding element head, then security is improved, but the key shaft dimensions are constrained

Engineering Contradiction:
Improvesecurity through obstruction of coding element headVSAvoidkey shaft dimensions
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

Instead of relying solely on the linear distance between drill protection elements, the invention utilizes the third dimension by positioning the drill protection elements such that they obstruct the path of the coding element head as it moves axially during key insertion. This dimensional approach allows for effective obstruction while maintaining standard key shaft dimensions, as the obstruction is achieved through the spatial arrangement rather than reduced spacing.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 enhances security by making drilling more difficult and provides noticeable mechanical resistance during key operation, ensuring higher locking security and tactile feedback.

Implementation Method 1

The spring element is tensioned when the coding element passes the drill protection elements. A portion of the head then contacts a section of the keyway, in particular a section of the drill protection element that crosses a groove of the keyway. This causes the head to be displaced into a cavity of the coding element.

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP4678857A1Key with a spring loaded coding element, lock cylinder with drill protection and closing device comprising a key and a lock cylinder
Publication Date: 2026.01.14 WILKA SCHLIESSTECHN
  • EP4678857A1 patent drawingFigure 1~2
  • EP4678857A1 patent drawingFigure 3~4
  • EP4678857A1 patent drawingFigure 5~6

AI summary

The invention relates to a locking device with a locking cylinder (1) and a key (30), wherein the key shaft (31) has a coding element (35) which has a head (36) which can spring from an operating position into a passing position into a cavity (39) in order to pass an obstacle (11) arranged in the key channel (10) or, in a fully inserted position, to move a locking element into a release position.