CV Joint Boot Mounting With Induction Heating Gap Control

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Solution Overview

Problem

The existing methods for mounting and fixing the boot of a constant velocity universal joint, such as using high-frequency induction heating or laser light, face challenges in achieving uniform adhesive strength, stability, and longevity of the high-frequency induction heating coil, while also increasing the complexity and cost of the assembly process.

Innovation Solution

A boot mounting method using high-frequency induction heating, where a heat-insulating material is interposed between the high-frequency induction heating coil and the boot end portion, maintaining a uniform gap for accurate heating and preventing coil damage, and a slit is formed in the receiving surface to enhance the anchor effect and joining strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fastening band is used to mount the boot, then the boot can be fixed to the mating member, but the number of components increases and assembly cost increases

Engineering Contradiction:
Improveboot fixation reliabilityVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the fastening band component from the assembly, replacing it with a direct integration method where the boot is mounted and fixed directly to the mating member without intermediate fastening elements, thereby reducing component count while maintaining fixation reliability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges the boot mounting and fixation functions into a single integrated process, combining what were previously separate operations (mounting with a band and fixing with another mechanism) into one unified attachment method that directly secures the boot to the mating member

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If a fastening band is used to mount the boot, then the boot can be fixed to the mating member, but manufacture cost for assembly increases

Engineering Contradiction:
Improveboot fixation reliabilityVSAvoidassembly cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

By extracting the fastening band component and its associated assembly operations, the invention eliminates the costs associated with purchasing, storing, and assembling the band, while the direct mounting method maintains sufficient fixation reliability for the application

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention discards the fastening band as a separate component entirely, recovering the cost benefits by simplifying the bill of materials and assembly process, while the boot itself serves the dual function of both sealing and fixation

Inventive Principle:
Principle #34Discarding and recovering

3Device complexity

If high-frequency induction heating is used to mount the boot, then the number of components is reduced, but the coil may be damaged due to lack of gap maintenance

Engineering Contradiction:
Improvenumber of componentsVSAvoidcoil lifetime
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The invention introduces a heat-insulating material as an intermediary element positioned between the high-frequency induction heating coil and the boot end portion, serving as a spacer that maintains the necessary gap to prevent coil damage while allowing the heating process to effectively warm the boot material for mounting

Inventive Principle:
Principle #24Intermediary (Mediator)

4Device complexity

If high-frequency induction heating is used to mount the boot, then the number of components is reduced, but uniform heating is difficult to achieve

Engineering Contradiction:
Improvenumber of componentsVSAvoidheating uniformity
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The heat-insulating material acts as a mediator that ensures uniform heat distribution by maintaining a consistent gap between the coil and boot surface, preventing hot spots and ensuring even heating across the entire boot end portion for reliable mounting

Inventive Principle:
Principle #24Intermediary (Mediator)

5Use of energy by moving object

If the boot end portion is heated directly without insulation, then heating efficiency is high, but the coil temperature rises excessively

Engineering Contradiction:
Improveheating efficiencyVSAvoidcoil temperature
Core Design Contradiction:
Use of energy by moving objectVSTemperature

Solution Approach 1:

The heat-insulating material serves as a thermal mediator that directs and confines the electromagnetic heating energy to the boot end portion while preventing excessive heat transfer to the coil, thereby maintaining heating efficiency for the boot while protecting the coil from temperature rise

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the potential harmful effect of heat transfer to the coil into a beneficial arrangement where the heat-insulating material prevents coil overheating while the heating process effectively mounts the boot, turning a thermal management challenge into a solution

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 method achieves uniform adhesive strength, stable joining, and longer coil lifetime, reducing the size and weight of the heating device, while preventing grease leakage and foreign matter entry, and maintaining sealability even under non-contact conditions.

Implementation Method 1

a high-frequency current is applied to the high-frequency induction heating coil. Specifically, the receiving surface of the mating member having conductivity is heated by high-frequency waves through the boot end portion

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a heat-insulating material is interposed between the high-frequency induction heating coil and the boot end portion, maintaining a uniform gap for accurate heating and preventing coil damage

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP3276198B1Boot attachment method and constant velocity universal joint
Publication Date: 2021.07.14 NTN CORP
  • EP3276198B1 patent drawingFigure 1
  • EP3276198B1 patent drawingFigure 2A~2B
  • EP3276198B1 patent drawingFigure 3

AI summary

Provided is a boot mounting method for a constant velocity universal joint in which a boot end portion is mounted and fixed to a mating member made of metal. After the boot end portion is fitted over a receiving surface being a radially outer surface of the mating member, a high-frequency induction heating coil having a ring shape is fitted over the boot end portion. Only a top portion of the receiving surface of the mating member is heated by high-frequency induction through application of a high-frequency current to the high-frequency induction heating coil. With this action, a mounting surface being a radially inner surface of the boot end portion and the receiving surface being the radially outer surface of the mating member are integrally joined to each other.