Conduit Outer Wall Protrusions Prevent Screw Penetration
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Solution Overview
Problem
Conventional synthetic resin conduits used in hot water supply systems are prone to damage and leakage due to contact with sharp screw tips in metallic outer tubes, leading to frequent replacements.
Innovation Solution
The conduit features thickened outer wall parts with protruding edges and ridged inner surfaces to reduce contact area and prevent screw penetration, combined with specific dimensions to enhance flexibility and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a thin-walled flexible conduit is used, then flexibility and ease of installation are improved, but resistance to screw scratching is worsened
Solution Approach 1:
The conduit wall thickness is not uniform but varies locally: thicker at the outer wall parts (convex portions) where screws may contact, and thinner at inner wall parts. This local quality variation provides both flexibility (thinner sections) and scratch resistance (thicker sections at critical locations).
Solution Approach 2:
The conduit is pre-formed with protruding parts at the outer wall parts before installation. These protruding parts serve as preliminary protective features that prevent screw tips from penetrating the conduit wall during the installation process, addressing the scratch resistance issue before the actual screw contact occurs.
2Reliability
If the conduit wall is thickened to prevent hole formation, then reliability is improved, but flexibility is worsened
Solution Approach 1:
The conduit employs non-uniform wall thickness distribution: outer wall parts have greater thickness (first thickness) for reliability and screw resistance, while inner wall parts have lesser thickness (second thickness) for flexibility. This local differentiation resolves the contradiction between reliability and flexibility.
Solution Approach 2:
The conduit wall is segmented into distinct regions: outer wall parts (convex portions) and inner wall parts (concave portions), each with different thickness characteristics. This segmentation allows each region to optimize for its specific function - protection versus flexibility.
3Strength
If protruding parts are added to outer wall parts, then resistance to screw penetration is improved, but manufacturing complexity is worsened
Solution Approach 1:
The protruding parts are not separate components but are integrated directly into the conduit wall structure itself. The outer wall parts form convex portions with inherent protrusions, merging the protective feature with the conduit body, thereby reducing overall device complexity while maintaining protection functionality.
Solution Approach 2:
The conduit structure utilizes parameter variations in the molding process, particularly in vacuum molding or blow molding, to create the desired wall thickness distribution and protruding features. By controlling molding parameters, the complex geometry is achieved through process optimization rather than additional manufacturing steps.
Data Source
AI summary
A conduit made of a synthetic resin, having an inner surface and an outer surface, having concave portions and convex portions alternately and continuously provided in the length direction. The conduit is bendable. The conduit includes outer wall parts extending with a first width in the length direction; inner wall parts positioned radially inside relative to the outer wall parts and extending with a second width in the length direction; and side wall parts joining the outer wall parts and the inner wall parts so that the outer wall parts and the inner wall parts are alternately and continuously provided in the length direction. The outer surfaces of the outer wall parts each have, at both ends in the length direction, protruding parts, which protrude in the radial direction.