Adjustable Return Spring Layout for Secure Lifting Hook Closure

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Solution Overview

Problem

Existing load attachment devices for helicopters, such as cargo hooks, face issues with spring distortion, premature damage, limited stiffness, and non-adjustable return force, which can lead to insecure closure and exposure to external elements.

Innovation Solution

A load attachment device with a return system featuring adjustable elastic means, including tension springs and a connecting rod with an adjustment nut, allowing for customizable return force and improved safety through parallel spring arrangement, ensuring secure hook closure and resistance to external factors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a spring is positioned horizontally between housing attachment point and hook pivot axis, then the spring can return the open hook to closed position, but the spring undergoes distortion and may break or suffer premature damage

Engineering Contradiction:
Improvespring durabilityVSAvoidspring resistance to distortion
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent makes the spring arrangement dynamic and adjustable rather than fixed. The spring can be repositioned along the rod at different locations, and the rod itself can be repositioned, allowing the system to adapt to different operational conditions and load requirements, thereby preventing distortion-related failures

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the physical parameters of the spring system by allowing variation in spring position, rod position, and spring orientation. This enables optimization of the spring's working conditions to minimize distortion and maximize durability under different operational scenarios

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If spring is located outside housing and hook, then it can function as return spring, but it is directly exposed to external aggressions such as sand and moisture

Engineering Contradiction:
Improvespring accessibilityVSAvoidexposure to sand and moisture
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The spring is nested within the housing structure, specifically positioned inside the housing cavity. The rod passes through the housing to connect the spring with the external hook, creating a nested arrangement where the spring is protected from external elements while still performing its return function

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The rod acts as an intermediary element that transmits the spring's force from its protected position inside the housing to the hook outside. This mediator allows the spring to remain shielded from sand and moisture while still effectively returning the hook to its closed position

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If return spring has fixed effective stiffness, then it is simple in structure, but it cannot be modified according to mission needs

Engineering Contradiction:
Improvereturn system simplicityVSAvoidadjustability of return force
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent introduces dynamic adjustability to the return system through the rod and spring positioning mechanism. The spring's effective stiffness can be modified by changing its position on the rod or repositioning the rod itself, allowing adaptation to different mission requirements without overcomplicating the overall structure

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The rod serves multiple functions: it acts as a support for the spring, a positioning element for adjusting spring location, and a connection member between the housing and hook. This multi-functionality provides adaptability while maintaining structural simplicity

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

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 adjustable return force system enhances the safety and reliability of load hook closure, providing increased stiffness and protection against environmental exposure, while allowing for tailored pre-tension adjustment based on mission requirements.

Implementation Method 1

a return system (10) comprising an elastic means (11) mounted between a rod (21) integral with said housing and a pin (14) fixed to the load hook (30), said return system being capable of exerting a return force on the load hook to allow the load hook to close

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3720769B1Hooking device comprising return system for lifting hook
Publication Date: 2022.06.08 LACE
  • EP3720769B1 patent drawingFigure 1
  • EP3720769B1 patent drawingFigure 2
  • EP3720769B1 patent drawingFigure 3~4

AI summary

The present invention relates to a return system (10) intended to equip a hooking device comprising a housing and a lifting hook (30) mounted so as to be able to pivot relative to the housing, the return system being mounted between a rod (21) secured to said housing, and comprising at least one traction spring (11), a device for adjusting the force of each traction spring with a plate (12) and a connecting rod (13) adjustably attached to the plate, and a handle (14) situated at a free end of the connecting rod, each traction spring links the rod to said plate, the handle is attached to the lifting hook, and the return system exerts a return force on the lifting hook that allows said lifting hook to close. The present invention also relates to a hooking device equipped with such a return system.