Cable Harness Water Cutoff Using Smooth Conductor Tube
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Solution Overview
Problem
Existing cable harnesses with grommets fail to effectively prevent water intrusion due to uneven outer wire bundles and gaps between electric wires and grommets, especially when high-frequency currents are involved, as resin penetration is incomplete, allowing electromagnetic waves to radiate and water to invade.
Innovation Solution
A cable harness with a smooth outer conductor tube and a braided wire electromagnetic shield, combined with an outside and inside water cutoff member, including a grommet and water cutoff cap, ensures complete water sealing by eliminating gaps and using a smooth surface contact to prevent water ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a braided wire electromagnetic shield is used to surround electric wires, then electromagnetic shielding is achieved, but gaps between element wires allow water invasion
Solution Approach 1:
The conductor tube is nested within the braided wire electromagnetic shield, creating a hierarchical structure where the smooth-walled tube provides water sealing while the outer braided shield provides electromagnetic protection. This nested arrangement allows both functions to coexist without compromising either performance.
Solution Approach 2:
The conductor tube acts as an intermediary element between the electric wires and the external environment. Its smooth outer peripheral surface prevents water invasion while maintaining the electromagnetic shielding function of the braided wire outer layer.
2Object-affected harmful factors
If resin is used to fill gaps between electric wires and grommet, then water cutoff is improved, but incomplete penetration allows water to invade through unfilled gaps
Solution Approach 1:
The problematic resin filling process is extracted and replaced with a mechanical sealing solution. The conductor tube's smooth outer surface directly contacts the grommet to form a reliable water seal, eliminating dependence on resin penetration and curing processes.
Solution Approach 2:
The chemical sealing mechanism (resin penetration and hardening) is replaced with a mechanical sealing system. The smooth outer peripheral surface of the conductor tube creates a reliable physical barrier against water invasion through direct contact with the grommet.
3Shape
If the outer circumference of the electric wire bundle is uneven, then individual wire shapes are maintained, but the grommet cannot make sufficient close contact allowing water invasion
Solution Approach 1:
The conductor tube serves as an intermediary between the uneven wire bundle and the grommet. Its smooth outer peripheral surface provides a uniform sealing interface that eliminates gaps, allowing the grommet to make complete contact while the tube maintains the necessary shape for electromagnetic shielding.
Data Source
AI summary
A cable harness includes a plurality of cables and an electrically-conductive outer conductor surrounding the plurality of cables. The outer conductor is partially constituted by a conductor tube having a smooth outer peripheral surface. An outside water cutoff member configured to prevent water from coming inside a hole of a body panel is placed between the smooth outer peripheral surface of the conductor tube and an edge of the hole of the body panel. Further, an inside water cutoff member having through holes through which the plurality of cables of the conductor tube passes, and configured to close an end of the conductor tube is provided.