Retractable Towing Hook Damping for End-Position Load Detection

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Solution Overview

Problem

Retractable towing hooks experience abrupt stops at end positions, leading to rapid increases in drive currents and torques, which existing control units have insufficient time to manage, resulting in potential damage.

Innovation Solution

Incorporating a damping element, such as a disc spring, into the actuator mechanism to retard the movement of mechanically cooperating parts, allowing a sensor unit to detect a gradual increase in load, enabling the control unit to stop the towing hook before harmful currents and torques are reached.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rigid mechanically cooperating parts are used in the actuator mechanism, then the structure is simple and strong, but the stop at end position becomes abrupt causing harmful currents and torques

Engineering Contradiction:
Improvestructural strengthVSAvoidharmful currents and torques
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

A damping element is introduced between the mechanically cooperating parts of the actuator mechanism to cushion the impact before the parts come into full abutment at the end position. This damping element absorbs the shock and prevents the abrupt stop that would otherwise cause harmful currents and torques in the electric motor.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Productivity

If the towing hook moves quickly to the end position, then productivity is improved, but the control unit has insufficient time to respond to the abrupt stop

Engineering Contradiction:
Improvemovement speedVSAvoidcontrol response time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The damping element provides a gradual deceleration phase before the towing hook reaches the end position, extending the time available for the control unit to detect the approaching stop condition and respond appropriately, thereby preventing harmful currents and torques even during high-speed operation.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Object-affected harmful factors

If pulse width modulation is used to slow down the towing hook, then harmful currents are reduced, but the control complexity increases

Engineering Contradiction:
Improveharmful currentsVSAvoidcontrol complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The damping element acts as a mechanical intermediary that physically slows down the approach to the end position, reducing harmful currents without requiring complex control algorithms. This mechanical cushioning simplifies the control task by providing a natural deceleration profile.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Object-affected harmful factors

If a damping element is added to the actuator mechanism, then the harmful currents and torques are reduced, but the device complexity increases

Engineering Contradiction:
Improveharmful currents and torquesVSAvoidactuator mechanism complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

A single damping element is strategically placed in the actuator mechanism to provide the necessary cushioning effect. This minimal addition effectively reduces harmful currents and torques without significantly increasing overall device complexity.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 damping element provides a controlled, gradual increase in load, giving the control unit more time to respond and prevent abrupt stops, thereby reducing peak drive currents and torques, ensuring safe operation of the retractable towing hook.

Implementation Method 1

at least one damping element configured to retard relative movement of the at least two mechanically cooperating parts as the two mechanically cooperating parts approach each other

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4311697A1A towing hook arrangement and a method for a towing hook arrangement
Publication Date: 2024.01.31 THULE TOWING SYST
  • EP4311697A1 patent drawingFigure 1
  • EP4311697A1 patent drawingFigure 2a
  • EP4311697A1 patent drawingFigure 2b~3

AI summary

The present disclosure relates to a towing hook arrangement (1) for determining an end-of-movement of a retractable towing hook (130). A sensor unit (70) is arranged to determine a load of an electrically driven actuator mechanism (100) and to communicate the determined load to a control unit (60). At least one damping element (80, 180, 280) is configured to retard relative movement of at least two mechanically cooperating parts (110, 120, 130, 170) as the two mechanically cooperating parts (110, 120, 130, 170) approach each other at the end-of-movement between a stowed position and a deployed position.