Motor Vehicle Tailgate Lock with Cam-Actuated Pawl

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Solution Overview

Problem

Existing motor vehicle locking devices with electric drives face challenges in securely maintaining end positions and achieving optimal noise behavior with a reduced number of drives, while being compact and cost-effective.

Innovation Solution

A motor vehicle locking device with a single electric drive and a control element featuring a cam mechanism that prevents overrunning of the central position, using a guide means and a spring element to ensure safe reaching and holding of functional positions, allowing for reliable operation and reduced component count.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If friction systems are used to maintain end positions, then the holding position is secured, but the device complexity increases and noise behavior deteriorates

Engineering Contradiction:
Improveholding position securityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces friction-based mechanical holding systems with a positive locking mechanism using a pawl and ratchet wheel. The pawl engages with the ratchet teeth to securely hold the drive element at end positions without relying on friction, thereby reducing device complexity and improving noise behavior while maintaining reliability.

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

Solution Approach 2:

The patent introduces a pawl as an intermediary element between the drive element and the locking mechanism. This pawl acts as a mediator that converts the rotational movement of the drive element into a secure locked position through positive engagement with the ratchet wheel, eliminating the need for complex friction-based holding systems.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If multiple electric drives are used to ensure secure end positions and optimal noise behavior, then reliability improves, but device complexity and cost increase

Engineering Contradiction:
Improveend position securityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the single electric drive multi-functional by equipping it with both a friction-based holding mechanism and a positive locking mechanism (pawl and ratchet). This allows one drive to perform multiple functions: maintaining holding positions through friction and securing end positions through positive locking, thereby eliminating the need for multiple separate drives while improving reliability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines two different locking mechanisms (friction-based holding and positive locking via pawl-ratchet) into a single integrated system that operates with one electric drive. This merging of functions allows the drive to securely maintain both intermediate holding positions and final end positions without requiring additional drives, reducing device complexity while enhancing reliability.

Inventive Principle:
Principle #5Merging (Combining)

3Device complexity

If a reduced number of electric drives is used, then device complexity and cost decrease, but the ability to securely maintain end positions and achieve optimal noise behavior deteriorates

Engineering Contradiction:
Improvedevice complexityVSAvoidend position security
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent replaces the need for multiple electric drives with a mechanical positive locking system (pawl and ratchet wheel). This mechanical substitution allows a single electric drive to securely maintain end positions through the pawl's engagement with the ratchet teeth, achieving reliable end position security without the complexity and cost of multiple drives.

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

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 enables secure and efficient operation of motor vehicle locking devices, such as tailgates, with minimal electric drives, preventing overrunning and ensuring safe positioning, thus enhancing reliability and cost-effectiveness.

Implementation Method 1

the control element has a control cam, by means of which the electric drive can be moved safely into functional positions

Methodology Applied
Scientific EffectCam mechanism: Cam

Implementation Method 2

the control element can be prestressed by means of a spring element

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 3

the publication discloses friction contacts that secure the holding position of the functional elements when the drive element is switched off

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3987136B1Closing device for a motor vehicle
Publication Date: 2023.06.07 KIEKERT AG
  • EP3987136B1 patent drawingFigure 1

AI summary

The invention relates to a motor vehicle closing device (1), in particular a tailgate lock, having an electrical drive (2) with at least one drive element (4) arranged after the electrical drive (2), wherein electrical opening and pulling closed are made possible by means of the drive element (4), wherein at least one anti-return means (5) is provided for the drive element (4), and wherein the anti-return means has a control element (5) with a control cam (17) for the drive element.