Telescopic Towing Hook Sealing for Axial and Rotational Motion

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Solution Overview

Problem

Existing retractable towing hooks face challenges in protecting the interface between moving parts due to complex movement patterns, as bellows seals are expensive and complex to develop, and do not adequately address both axial and rotational movements.

Innovation Solution

A sealing arrangement with a telescopic design comprising a first and second housing part that allows for both axial and rotational movements, ensuring sealing contact at end positions and optional fluid connection during movement, using flexible sealing lips to manage pressure equalization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If bellows seal is used to protect the interface between moving parts, then the sealing capability is improved, but the device complexity and cost increase

Engineering Contradiction:
Improvesealing capabilityVSAvoidsealing system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sealing system is divided into multiple sealing elements (first sealing element on the rotating element, second sealing element on the housing) that work together to seal the interface. This segmentation allows each sealing element to handle specific aspects of the sealing requirement, reducing the complexity of any single sealing component while maintaining overall sealing effectiveness.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses flexible sealing lips (first and second sealing lips) that can deform to accommodate the complex helical movement between the rotating element and housing. These flexible thin film elements provide effective sealing without requiring complex rigid structures, thus reducing device complexity while maintaining sealing capability.

Inventive Principle:
Principle #30Flexible shells and thin films

2Adaptability or versatility

If bellows seal is used to accommodate complex movement, then the adaptability to movement patterns is improved, but the manufacturing cost increases

Engineering Contradiction:
Improvemovement accommodation capabilityVSAvoidmanufacturing cost
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The sealing system is designed to dynamically adapt to the helical movement pattern through the coordinated rotation and axial movement of the rotating element. The flexible sealing lips dynamically deform to maintain contact with the mating surfaces throughout the movement cycle, providing adaptability to complex movement without requiring expensive bellows structures.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the geometric parameters of the sealing surfaces and sealing lips to accommodate the specific helical movement pattern. By optimizing the shape and positioning of the sealing elements according to the movement trajectory, the system achieves high adaptability to the complex movement while using simple, cost-effective manufacturing processes.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If telescopic housing parts are used for sealing contact, then the cost and complexity are reduced, but the ability to handle complex movement is limited

Engineering Contradiction:
Improvesealing system simplicityVSAvoidmovement handling capability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent merges two sealing systems (first sealing element with first sealing lip, and second sealing element with second sealing lip) that work together to handle the complex helical movement. This combination of multiple simple sealing elements achieves the movement handling capability of complex seals while maintaining the simplicity and low cost of basic sealing designs.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The sealing system operates in multiple dimensions by accommodating both rotational movement and axial movement simultaneously. The first and second sealing elements are positioned and oriented to seal interfaces in different dimensional aspects of the helical movement, enabling the simple telescopic housing design to handle complex multi-dimensional movement patterns.

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

Data Source

PatentEP4324665B1A sealing arrangement for a retractable towing hook
Publication Date: 2026.04.15 THULE TOWING SYST
  • EP4324665B1 patent drawingFigure 1~2
  • EP4324665B1 patent drawingFigure 3
  • EP4324665B1 patent drawingFigure 4~5

AI summary

The disclosure relates to sealing arrangement (1) for enclosing and protecting an interface between a first element (10) and a second element (20) of a retractable towing hook assembly (500). The second element (20) being movable relative to the first element (10) along a longitudinal axis (A), and rotatable relative to the first element (10) about the longitudinal axis (A). The sealing arrangement (1) comprises a first housing part (100) fixedly attachable to the first element (10), and a second housing part (200) fixedly attachable to the second element (20). The first housing part (100) and the second housing part (200) are arranged to cooperate telescopically during relative movement between the first housing part (100) and the second housing part (200) between a first position and a second position. The first housing part (100) is arranged to be in sealing contact with the second housing part (200) at least in the first position and in the second position. The disclosure also relates to a towing hook arrangement comprising the sealing arrangement and to a vehicle comprising the towing hook arrangement.