Motor Vehicle Door Lock Coupling Lever for Crash-Safe Opening

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing motor vehicle door locks with switchable clutch elements face reliability issues due to factors like corrosion and contamination, leading to inconsistent functionality over time, especially during crash scenarios.

Innovation Solution

The door lock design incorporates two pivotable levers with a clutch element mounted between them, ensuring engagement only within a predetermined pivot angle range and below a specific speed, using a torsion spring for reliable operation, independent of dirt or corrosion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a spring-elastic wire or strip is used as the clutch element to enable disengagement during crashes, then the lock can remain closed during normal operation, but the spring elasticity changes over time due to corrosion and contamination, leading to unreliable functionality

Engineering Contradiction:
Improvecrash scenario functionalityVSAvoidservice life
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent replaces the spring-elastic wire or strip with a magnet and a magnetically actuated clutch element. The magnetic field replaces the mechanical spring elasticity, providing a contactless actuation mechanism that does not degrade from corrosion or contamination. The magnet is arranged to interact with the clutch element through a non-contact magnetic field, eliminating the need for elastic deformation of metal components.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical state and properties of the actuation mechanism from mechanical elasticity to magnetic field interaction. By using a magnet with specific magnetic properties and arranging it to interact with the clutch element, the system achieves reliable disengagement without relying on the deteriorating spring elasticity of metal wires or strips.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a clutch pin and clutch cam design is used in the actuating lever chain, then the transmission can be activated in the resting state to interrupt the actuating lever chain, but contamination and corrosion occur between the clutch pin and clutch cam, impairing functional reliability

Engineering Contradiction:
Improvelocking functionalityVSAvoidcorrosion and contamination
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical clutch pin and clutch cam interaction with a magnetic field-based actuation system. The magnet actuates the clutch element without physical contact, eliminating the surfaces that would otherwise be subject to corrosion and contamination. This contactless magnetic actuation removes the harmful mechanical interfaces entirely.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary between the actuator and the clutch element. Instead of direct mechanical contact between metal components, the magnetic field serves as the mediating force that transfers energy and motion, preventing direct contact and thus preventing corrosion and contamination at the interface.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If the actuating lever chain is designed to allow manual opening via handles, then the lock can be opened in normal operation, but during crashes the lever performs a free stroke due to inertial delay, which may not reliably prevent unintended opening

Engineering Contradiction:
Improvemanual openingVSAvoidcrash scenario protection
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent designs the magnetic actuation system to respond dynamically to acceleration forces. The magnet and clutch element are arranged so that during normal operation, the clutch element remains engaged allowing manual opening. During crashes, the inertial forces cause the magnet and clutch element to separate, automatically disengaging the clutch and interrupting the actuating lever chain to prevent unintended opening.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent pre-arranges the magnetic field interaction and clutch element geometry so that the system is prepared to respond to crash conditions. The magnet and clutch element are positioned and dimensioned to ensure that under normal gravitational and operational conditions, engagement is maintained, but under crash accelerations, the magnetic coupling fails and disengagement occurs, providing preliminary protection against unintended opening.

Inventive Principle:
Principle #9Preliminary anti-action

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

Ensures permanent functional reliability by preventing unintended lock opening during normal operation and crashes, maintaining consistent performance over long periods without mechanical impairments.

Implementation Method 1

using a torsion spring for reliable operation

Methodology Applied
Scientific EffectTorsion spring: Torsion Spring

Data Source

PatentEP3990726B1Door lock, in particular a motor vehicle door lock
Publication Date: 2025.12.17 KIEKERT AG
  • EP3990726B1 patent drawingFigure 1
  • EP3990726B1 patent drawingFigure 2
  • EP3990726B1 patent drawingFigure 3

AI summary

The invention relates to a door lock, in particular a motor vehicle door lock, comprising a locking mechanism (1, 2) which consists substantially of a rotary latch (1) and a pawl (2). An actuating lever chain (5, 6, 7, 8) is also provided at least for opening the locking mechanism (1, 2), wherein the actuating lever chain (5, 6, 7, 8) comprises at least one switchable coupling element (7) which drivingly closes the actuating lever chain (5, 6, 7, 8) when in the "coupled" position and drivingly opens the actuating lever chain when in the "uncoupled" position. According to the invention, the actuating lever chain (5, 6, 7, 8) comprises at least two levers (5, 6) which can be pivoted about a common axis (9). In addition, the coupling element (7) is in the form of a coupling lever (7) that is pivotally mounted on the first lever (5), which coupling lever, starting from the uncoupled state thereof that is adopted when idle, engages by means of its catch (13) in a recess (14) in the adjacent second lever (6) of the actuating lever chain (5, 6, 7, 8) in order to adopt the coupled state.