Composite Cable Inward Projections Prevent Buckling
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Solution Overview
Problem
The composite cable disclosed in JP 2014/220043 A is prone to buckling and tape member movement when bent or twisted, leading to decreased flexibility and workability due to the formation of large hollow portions and tape member overlap.
Innovation Solution
A composite cable design featuring a pair of first electric wires, a twisted pair wire with a smaller outer diameter, a tape member spirally wound around the assembly of both, and a sheath with inwardly projecting parts to prevent buckling and tape member movement, where the twisting direction of the assembly and winding direction of the tape member are the same, and the inwardly projecting parts are at least 3% of the outer diameter of the first electric wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a tape member is wound around electric wires to enable easy sheath removal, then ease of manufacture is improved, but hollow portions form around wires causing buckling when bent or twisted
Solution Approach 1:
The patent applies local quality by creating inwardly projecting parts at specific locations (valley parts between wires) rather than uniform structure throughout. These localized projections fill hollow portions only where needed, preventing buckling at critical points while maintaining the overall spiral tape structure for easy sheath removal.
Solution Approach 2:
The inwardly projecting parts are formed in advance during cable assembly, before the cable is put into service. This preliminary action of pre-filling the hollow portions ensures that when the cable is later bent or twisted, the buckling-resistant structure is already in place, preventing deformation issues.
2Ease of manufacture
If the tape member is wound spirally around electric wires, then ease of sheath removal is improved, but the tape member moves in cable longitudinal direction causing overlap and decreased flexibility
Solution Approach 1:
The patent uses local quality by placing inwardly projecting parts at specific valley parts between wires rather than uniformly throughout. These localized structures anchor the tape member at critical points, preventing longitudinal movement and overlap, while maintaining the spiral winding structure that enables easy sheath removal.
Solution Approach 2:
The inwardly projecting parts act as intermediaries between the tape member and the electric wires. They provide anchoring points that prevent the tape member from moving longitudinally, while still allowing the spiral structure to function for easy sheath removal. The projections mediate between the conflicting requirements of tape mobility and stability.
3Ease of manufacture
If hollow portions are formed around electric wires by winding tape member, then ease of sheath removal is improved, but buckling occurs when cable is bent or twisted
Solution Approach 1:
The patent applies local quality by forming inwardly projecting parts only at specific valley parts between wires rather than uniformly filling all hollow portions. This localized approach provides sufficient buckling resistance at critical points while maintaining the overall spiral tape structure for easy sheath removal.
Solution Approach 2:
The patent segments the hollow portions into discrete valley parts between wires, and addresses each segment individually with inwardly projecting parts. This segmentation allows the solution to target specific problem areas without compromising the overall structure needed for easy sheath removal.
Data Source
AI summary
A composite cable includes a pair of first electric wires, a twisted pair wire formed by twisting a pair of second electric wires having a smaller outer diameter than the first electric wires, a tape member wound into a spiral around an assembly that is formed by twisting the pair of first electric wires and the twisted pair wire together, and a sheath covering an outer periphery of the tape member. The tape member and the sheath includes an inwardly projecting part formed in a spiral along a cable longitudinal direction and formed so as to enter inward at least one of a valley part between the two first electric wires and valley parts between the first electric wires and the twisted pair wire. The inwardly projecting part has a projecting length of not less than 3% of an outer diameter of the first electric wires.