Metal-Fitting Hose Sleeve Structure for Crack-Resistant Junctions
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Solution Overview
Problem
Existing hoses with metal fittings, such as brake hoses, face durability issues due to stress concentration at the junctions, leading to cracks and potential fluid leakage, especially under vibration and bending conditions.
Innovation Solution
A hose with a metal fitting is designed with a sleeve covering the junction between the hose and the metal fitting, featuring a first cylindrical portion covering the metal-fitting cylindrical portion and a second cylindrical portion with a smaller diameter and thickness, and optionally a leaning portion, made of thermoplastic elastomer or rubber, to distribute stress and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a metal fitting is connected to the hose end portion, then the hose can be structurally assembled, but stress concentrates at the junction causing cracks and reducing durability
Solution Approach 1:
A sleeve made of elastomer or rubber is introduced as an intermediary component between the metal fitting and the hose. This sleeve covers the junction area and distributes the stress that would otherwise concentrate at the metal-hose interface, preventing crack formation while maintaining structural assembly
Solution Approach 2:
The sleeve material properties (elastomer or rubber with specific hardness and elasticity) are selected to change the mechanical parameters at the junction area. The material's ability to deform and return to original shape helps absorb and distribute stress, preventing the stress concentration that leads to cracking
2Adaptability or versatility
If the hose is subjected to vibration and bending, then the hose performs its function in vehicle applications, but cracks occur at the junction reducing durability
Solution Approach 1:
The elastomer or rubber material of the sleeve is selected for its specific mechanical properties including elasticity, hardness, and damping characteristics. These parameter changes allow the sleeve to absorb vibration energy and accommodate bending movements without transmitting excessive stress to the hose junction, maintaining durability under dynamic conditions
Solution Approach 2:
The elastomer or rubber sleeve acts as a pre-installed cushioning element at the vulnerable junction area. Before vibration and bending occur, the sleeve is already in place to absorb and distribute the incoming mechanical stresses, preventing crack initiation under dynamic loading conditions
Data Source
AI summary
A hose with a metal fitting includes a hose, a metal fitting connected to an end portion of the hose, and a sleeve covering at least a portion of the hose and metal fitting. The inside of the hose communicates with the inside of the metal fitting. The hose includes an inner-surface resin layer, a metal-wire reinforced layer, and an outer-surface resin layer. The sleeve includes a first cylindrical portion covering a portion of the metal fitting and a second cylindrical portion directly covering a portion of the hose. The length of the second cylindrical portion is 8 mm or more. The thickness of the second cylindrical portion is 1 mm or more. The hardness of the second cylindrical portion is measured in compliance with JISK6253 by Durometer Type A and is between 70 and 95. The material of the sleeve and the outer-surface resin layer are the same.