Coupling Device Transfer Linkage for Towing Hook Engagement

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Solution Overview

Problem

Existing coupling devices for load carriers on vehicles lack a stable and quick attachment mechanism to towing hooks, requiring complex lever and clamp operations and inadequate clamping force for secure attachment.

Innovation Solution

A compact coupling device with a transfer linkage system using two-bar linkages that allows for single-motion engagement and release, providing a high clamping force through angular relationships between link bars, ensuring secure attachment of load carriers to towing hooks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a traditional lever and clamp mechanism is used for coupling, then the coupling device can engage the towing hook, but the attachment process becomes complex and time-consuming requiring multiple operations

Engineering Contradiction:
Improveease of attachmentVSAvoidmechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent combines the lever and clamp into a single integrated coupling element that performs both functions simultaneously. The coupling element itself acts as the clamp that engages the towing hook, eliminating the need for a separate clamp mechanism. This merging reduces the number of操作步骤 from multiple (lever actuation plus clamp engagement) to a single motion, directly resolving the contradiction between ease of operation and device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts and eliminates the separate clamp component from the traditional lever-clamp mechanism. By removing the clamp as a distinct element and integrating its function into the coupling element, the device complexity is reduced while maintaining the ability to securely engage the towing hook, thus resolving the contradiction between operational simplicity and mechanism complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

2Strength

If a traditional coupling mechanism is used, then the structure can provide some attachment force, but the clamping force is insufficient for secure attachment of heavy loads

Engineering Contradiction:
Improveclamping forceVSAvoidmechanism complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The spring element is pre-loaded to store elastic potential energy before engagement. When the coupling element engages the towing hook, this pre-stored energy is released to generate high clamping force automatically. This preliminary action of pre-loading the spring eliminates the need for complex force multiplication mechanisms, achieving high clamping force with simple structure.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The spring-loaded coupling element is self-actuating - it automatically generates and applies the clamping force through its own pre-compressed spring energy without requiring external actuators or complex mechanical advantage systems. This self-service mechanism achieves high clamping force while maintaining structural simplicity, resolving the contradiction between strength and device complexity.

Inventive Principle:
Principle #25Self-service

3Volume of moving object

If a compact coupling device is designed, then the device size is reduced, but the ability to provide sufficient clamping force for stable coupling is compromised

Engineering Contradiction:
Improvedevice sizeVSAvoidclamping force
Core Design Contradiction:
Volume of moving objectVSStrength

Solution Approach 1:

The patent changes the energy storage parameter by using a pre-compressed spring element that stores elastic potential energy in a compact form. This allows the generation of high clamping force from a small volume, as the spring's elastic energy density provides the necessary force without requiring large mechanical structures or complex force multiplication mechanisms, thus resolving the contradiction between compact size and clamping force capability.

Inventive Principle:
Principle #35Parameter changes

4Loss of time

If the coupling device is designed for quick release, then the removal time is reduced, but the reliability of the engaged state may be compromised

Engineering Contradiction:
Improveremoval timeVSAvoidcoupling reliability
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The coupling element with its spring-loaded design is self-actuating in both engagement and release. The same spring force that provides secure engagement can be easily reversed by applying a small release force, enabling quick release while maintaining engagement reliability. This self-service mechanism eliminates the need for separate locking and release mechanisms, achieving both quick release and reliable engagement with simple structure.

Inventive Principle:
Principle #25Self-service

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

Enables quick and secure attachment of load carriers to towing hooks with a single force application, providing a stable and safe coupling that can handle significant loads, while being easy to install and remove, and includes an optional locking mechanism for theft prevention.

Implementation Method 1

The first and second two-bar linkages are arranged in relation to each other such that when a force is applied to the second two-bar linkage the force is transferred via the first two-bar linkage to the first coupling element

Methodology Applied
Scientific EffectForce transfer through linkage: Mechanical Advantage

Implementation Method 2

The first link bar and the second link bar of the first two-bar linkage are arranged at an angle within an interval of 135 - 180 degrees when the towing hook is engaged and the third link bar and the fourth link bar of the second two-bar linkage are arranged at an angle within an interval of 135 - 180 degrees when the towing hook is engaged

Methodology Applied
Scientific EffectMechanical advantage through angular geometry: Mechanical Advantage

Data Source

PatentEP2213516B1Coupling device
Publication Date: 2012.07.11 THULE SWEDEN AB
  • EP2213516B1 patent drawingFigure 1~2
  • EP2213516B1 patent drawingFigure 3
  • EP2213516B1 patent drawingFigure 4

AI summary

A coupling device (1) for coupling a load carrier to a towing hook (2) of a vehicle, which device comprises, a first coupling element (4) adapted to abut against a first portion of the towing hook (2) and a second coupling element adapted to abut a second portion of the towing hook (2). A frame (10) is arranged to accommodate at least the first portion of the towing hook (2) and a transfer linkage (12) for effecting displacement of the first coupling element (4) with respect to the frame (10). The first coupling element (4) is movably connected to the frame (10) and is associated with an end of the transfer linkage (12). The transfer linkage (12) comprises a first two-bar linkage (22) and a second two-bar linkage. The first and second two-bar linkages (22) are arranged in relation to each other such that when a force is applied to the second two-bar linkage the force is transferred via the first two-bar linkage (22) to the first coupling element (4) via the said end of the transfer linkage (12) for releasing or engaging the towing hook (2). Link bars of the two-bar linkages are in a defined angular relationship when the towing hook is engaged. A load carrier and use of a load carrier are also presented.