Nested Heat Shrink Tubes for High-Temperature Cable Waterproofing

Solution Overview

Problem

Existing cable waterproof structures for electric brake systems in vehicles, such as those using heat shrinkable tubes with adhesive, fail to ensure waterproofness at high temperatures due to the adhesive melting and the resin tube slipping out of the sheath, even when using additional fixing methods like INSULOK or low temperature shrink tubes.

Innovation Solution

A cable waterproof structure comprising a heat shrinkable tube with adhesive that covers the sheath and insulated wires, and a fixing heat shrinkable tube with no adhesive, where the shrinkage start temperature of the fixing tube is higher than that of the adhesive tube, ensuring the adhesive tube is pushed in and secured before the fixing tube shrinks, preventing slipping and wrinkles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a heat shrinkable tube with adhesive is provided to cover the sheath and insulated wires, then waterproofness is improved, but the adhesive melts and the tube slips out under high temperature environment (not less than 120°C)

Engineering Contradiction:

ImprovewaterproofnessVSAvoidhigh temperature resistance

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent applies nesting by placing a low temperature shrink type heat shrinkable tube inside the heat shrinkable tube with adhesive. The inner tube shrinks first at lower temperature to push the adhesive tube inward and secure it, while the outer tube provides the waterproof seal. This nested configuration allows the adhesive tube to benefit from the stabilizing effect of the inner tube without compromising its waterproof function.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent changes the shrinkage temperature parameter by introducing a low temperature shrink type heat shrinkable tube with a shrinkage start temperature lower than that of the adhesive tube. This parameter difference enables sequential shrinking: the inner tube shrinks first to stabilize the structure, then the outer adhesive tube shrinks to provide waterproofing without slipping out.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If a low temperature shrink type heat shrinkable tube is provided outside to prevent slipping, then high temperature resistance is improved, but the adhesive tube may be pushed out and slipped out or wrinkles may form

Engineering Contradiction:

Improvehigh temperature resistanceVSAvoidwaterproofness

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent applies nesting by placing a low temperature shrink type heat shrinkable tube inside the heat shrinkable tube with adhesive. The inner tube shrinks first at lower temperature to push the adhesive tube inward and secure it, while the outer tube provides the waterproof seal. This nested configuration allows the adhesive tube to benefit from the stabilizing effect of the inner tube without compromising its waterproof function.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent changes the shrinkage temperature parameter by introducing a low temperature shrink type heat shrinkable tube with a shrinkage start temperature lower than that of the adhesive tube. This parameter difference enables sequential shrinking: the inner tube shrinks first to stabilize the structure, then the outer adhesive tube shrinks to provide waterproofing without slipping out.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If multiple heat shrinkable tubes are provided with different shrinkage temperatures, then high temperature resistance is improved, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvehigh temperature resistanceVSAvoidstructure complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent applies nesting by placing a low temperature shrink type heat shrinkable tube inside the heat shrinkable tube with adhesive. The inner tube shrinks first at lower temperature to push the adhesive tube inward and secure it, while the outer tube provides the waterproof seal. This nested configuration allows the adhesive tube to benefit from the stabilizing effect of the inner tube without compromising its waterproof function.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent changes the shrinkage temperature parameter by introducing a low temperature shrink type heat shrinkable tube with a shrinkage start temperature lower than that of the adhesive tube. This parameter difference enables sequential shrinking: the inner tube shrinks first to stabilize the structure, then the outer adhesive tube shrinks to provide waterproofing without slipping out.

Inventive Principle:

Principle #35Parameter changes

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

This configuration provides a more reliable waterproof seal at high temperatures, preventing water ingress and maintaining integrity even when exposed to temperatures above 120°C, as confirmed by testing where the waterproofness is maintained for at least 1 hour at 140°C.

Implementation Method 1

a heat shrinkable tube with adhesive that comprises adhesive inside, and is provided and shrunk so as to cover an end of the sheath and a circumference of the plurality of insulated wires extended from the end of the sheath

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 2

a fixing heat shrinkable tube that comprises no adhesive inside, and is provided and shrunk so as to cover a part of the heat shrinkable tube with adhesive that covers the sheath and a circumference of the sheath extended from the heat shrinkable tube with adhesive

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 3

the adhesive melts and the resin tube shrinks again under high temperature environment, for example, at not less than 120° C

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS10304590B2Cable waterproof structure, wire harness, and method of manufacturing wire harness

Publication Date: 2019.05.28 PROTERIAL LTD

AI summary

A cable waterproof structure includes a plurality of insulated wires and a sheath covering the plurality of insulated wires collectively, a heat shrinkable tube with adhesive that includes adhesive inside, and is provided and shrunk so as to cover an end of the sheath and a circumference of the plurality of insulated wires extended from the end of the sheath, and a fixing heat shrinkable tube that includes no adhesive inside, and is provided and shrunk so as to cover a part of the heat shrinkable tube with adhesive that covers the sheath and a circumference of the sheath extended from the heat shrinkable tube with adhesive, wherein a shrinkage start temperature of the fixing heat shrinkable tube is higher than a shrinkage start temperature of the heat shrinkable tube with adhesive.