Tie-down bar with dual spring stiffness for consistent load retention
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Solution Overview
Problem
Conventional securing bars for vehicles lack versatility and reliability in installation, often requiring specific vehicle features like rails, and fail to ensure consistent load retention due to variable locking forces, which can be too low for safety or too high for vehicle damage, and are cumbersome to handle and store.
Innovation Solution
A securing bar with a main shaft and two sliders, one with flexible return means for easy installation and another with hard return means for controlled locking, allowing for consistent load retention without specific vehicle modifications, and enabling easy one-handed operation and efficient storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single spring mechanism is used for bar installation, then the structure is simple, but the locking force varies according to user application making load retention inconsistent
Solution Approach 1:
The spring mechanism is segmented into two distinct springs: a first spring (133, 134) with low stiffness for installation phase and a second spring (142) with high stiffness for locking phase. This segmentation allows each spring to perform its specific function optimally, ensuring consistent locking force while maintaining reliable load retention.
Solution Approach 2:
Different parts of the system have different spring characteristics tailored to their specific functions. The first spring has low stiffness localized for easy installation, while the second spring has high stiffness localized for strong locking. This local quality differentiation resolves the contradiction between reliability and complexity.
2Reliability
If strong compression is applied during fine adjustment to ensure locking force, then load retention is improved, but the vehicle walls may be damaged
Solution Approach 1:
The system changes the stiffness parameter of the spring mechanism based on the operational phase. During installation, low stiffness allows gentle placement; during locking, high stiffness provides strong compression. This parameter change ensures sufficient locking force without excessive compression that could damage vehicle walls.
3Manufacturing precision
If the bar length is adjusted to be slightly greater than the distance between walls for proper fit, then installation accuracy is improved, but handling becomes more difficult
Solution Approach 1:
The bar system transitions from a static rigid structure to a dynamic adjustable structure during installation. The low-stiffness first spring allows the bar to be compressed and positioned dynamically, making handling easier while achieving precise fit. The rigid structure is restored after locking for load-bearing function.
4Reliability
If a blocking plate is added to prevent slider movement, then locking reliability is improved, but the device complexity increases
Solution Approach 1:
The blocking plate (114) is merged with the second slider assembly, integrating the blocking function into the existing slider structure. This merging reduces the need for separate blocking components while maintaining reliable locking, thus improving reliability without proportionally increasing complexity.
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 allows for simple, quick, and consistent load retention across various vehicles, ensuring safety without damaging the vehicle and facilitating easy handling and storage, as the locking force is always predetermined and the bar can be easily repositioned and stored.
Implementation Method 1
a locking slider (140) movable in translation with respect to said main shaft (130) and associated with a first return means (142), called hard
Implementation Method 2
a positioning slider (110) movable in translation with respect to said main shaft (130) and associated with second return means (133, 134), called flexible
Implementation Method 3
The intensity of the compression, which is linked to the coefficient of friction of the pads with the walls of the vehicle, defines the effectiveness of the blocking of bar
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
The invention relates to a tie-down bar (100) designed to extend between two support surfaces of a vehicle, comprising a main shaft (130) and a locking slide (140) movable in translation relative to the main shaft (130) and associated with first return means (142), referred to as rigid, and a locking handle (112) for the position of the locking slide (140) relative to the main shaft. The tie-down bar includes a second slide, referred to as the positioning slide (110, 120), movable in translation relative to the main shaft (130) and associated with second return means (133, 134), referred to as flexible, said second return means being positioned around a rod fixed to said main shaft, and the stiffness of the first return means (142) being greater than the stiffness of the second return means (133, 134).The lashing bar also includes means for blocking the translation of the positioning slide (110, 120) relative to the main shaft (130).