Dual Elastomeric Hose Layers for High-Pressure Bonding
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Solution Overview
Problem
Existing flexible hoses for high-pressure applications, such as automotive power steering, face challenges with high costs due to expensive hydrogenated nitrile butadiene rubber (HNBR) and inadequate bonding between thermoplastic and reinforcing layers, leading to insufficient mechanical strength and pressure resistance.
Innovation Solution
A flexible hose design featuring two elastomeric inner layers, with a thinner hydrogenated nitrile butadiene rubber (HNBR) layer and a thicker nitrile butadiene rubber (NBR) layer, directly connected without intermediate layers, providing mechanical strength and adhesion to a reinforcing layer with metal wires, eliminating the need for thermoplastic materials and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermoplastic layer is used adjacent to the innermost HNBR layer, then the hose achieves good chemical and temperature resistance, but the connection to the reinforcing layer becomes insufficient
Solution Approach 1:
The patent uses a composite structure with an innermost HNBR layer for chemical and temperature resistance, combined with an outer NBR layer that provides good adhesion to the reinforcing layer. This composite material approach allows each layer to contribute its specific properties, resolving the contradiction between chemical resistance and bond strength.
2Reliability
If HNBR material is used for the innermost layer, then the hose achieves high temperature and chemical resistance, but the manufacturing cost increases
Solution Approach 1:
The patent applies local quality by using HNBR only in the innermost layer where it is most needed for chemical and temperature resistance, while using the less expensive NBR material for the outer layer. This localized application of expensive material optimizes the balance between performance and cost.
Solution Approach 2:
The composite structure combines expensive HNBR with cheaper NBR, allowing the hose to achieve the required temperature and chemical resistance while reducing overall material costs compared to using HNBR throughout the entire hose structure.
3Ease of manufacture
If the first elastomeric inner layer is made thinner, then the costs for the hose are reduced, but the mechanical strength may be compromised
Solution Approach 1:
The patent applies local quality by making the HNBR layer thinner where full thickness is not needed, while maintaining sufficient thickness of the NBR outer layer to provide the required mechanical strength and adhesion. This optimized thickness distribution reduces costs while maintaining performance.
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 hose achieves enhanced temperature and chemical resistance, improved mechanical strength, and increased pressure resistance while being more cost-effective, adhering to DIN EN 856 standards, with a robust connection between layers ensuring reliable performance under high pressures.
Implementation Method 1
The innermost layer made of HNBR is able to withstand chemical and temperature degradation
Implementation Method 2
the chemically connection is implemented by vulcanisation
Data Source
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AI summary
The present invention refers to hose (10), which is suitable for high pressure applications and a method for producing same. The hose (10) contains a flexible inner tube (17). The inner tube (17) is made of two different elastomeric materials. A first elastomeric inner layer (13) defines a fluid channel (14) of the hose (10) along its longitudinal axis (11). Directly on the outer surface (16) of the first elastomeric inner layer (13), a second elastomeric inner layer (15) is attached. The first elastomeric inner layer (13) is made of hydrogenated nitrile butadiene rubber (HNBR). The second elastomeric inner layer is preferably made of nitrile butadiene rubber (NBR). The two inner layers (13, 15) are connected to each other by a vulcanization process. Around the inner tube (17) a reinforcing layer (21) is provided which is covered by a cover layer (26). Between the reinforcing layer (21) and the inner tube (17) no additional intermediate layers are provided.