Double-Walled Ball Joint Cap Heat Insulation

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Solution Overview

Problem

Existing ball joint assembly processes require the sealing bellows to be installed after hot hammering, as previous protective caps fail to adequately protect against radiant heat, leading to increased costs and complexity due to the need for additional work steps and bulkier sub-assemblies.

Innovation Solution

A double-walled protective cap with an air intermediate layer, made of plastic, provides effective heat insulation by creating a space between its walls, allowing the sealing bellows to be integrated before hot hammering, thus preventing damage from radiant heat during the hot hammering process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single-walled protective cap is used to cover the sealing bellows during hot hammering, then the assembly process is simplified, but the sealing bellows is not sufficiently protected against radiant heat

Engineering Contradiction:
Improveassembly process simplicityVSAvoidheat protection effectiveness
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The protective cap transitions from a single-walled structure to a double-walled structure with an intermediate air gap. This dimensional change adds a thermal insulation layer without significantly increasing assembly complexity, effectively blocking radiant heat from reaching the sealing bellows while maintaining ease of manufacture.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

An air gap is introduced as an intermediary layer between the hot hammering environment and the sealing bellows. This air layer acts as a thermal insulator, mediating the heat transfer and protecting the temperature-sensitive sealing bellows from damaging radiant heat while allowing the hot hammering process to proceed.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the sealing bellows is installed after hot hammering, then it is protected from heat damage, but the production process becomes more complex and time-consuming

Engineering Contradiction:
Improvesealing bellows protectionVSAvoidproduction process efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The sealing bellows is installed on the ball joint shaft before the hot hammering process begins. The double-walled protective cap is then placed over the assembly to provide heat protection during hot hammering. This preliminary installation eliminates the need for separate installation steps after hot hammering, streamlining the production process while ensuring the sealing bellows remains protected throughout.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The double-walled protective cap with its air gap provides beforehand cushioning against radiant heat before the hot hammering process exposes the sealing bellows to high temperatures. This pre-established protection allows the sealing bellows to remain in place during hot hammering without risk of heat damage, improving productivity while maintaining reliability.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If the end section of the connecting tube is heated to high temperatures for hot hammering, then a tight fit is achieved, but the sealing bellows is exposed to damaging radiant heat

Engineering Contradiction:
Improvejoint connection tightnessVSAvoidradiant heat exposure
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The protective cap is divided into two walls with an intermediate air gap, creating separate thermal zones. The outer wall faces the hot hammering environment while the inner wall protects the sealing bellows. This segmentation allows the end section of the connecting tube to be heated to high temperatures for a tight fit while the air gap blocks radiant heat from reaching the sealing bellows.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The air gap between the two walls of the protective cap serves as an intermediary thermal barrier. It allows the hot hammering process to proceed at high temperatures to achieve a tight fit between the ball joint shaft and connecting tube, while simultaneously protecting the sealing bellows from damaging radiant heat through the insulating air layer.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables the integration of the sealing bellows before hot hammering, reducing production costs and complexity by maintaining the protective cap's effectiveness throughout the assembly and subsequent handling stages, including surface treatments and transportation.

Implementation Method 1

A double-walled protective cap with an air intermediate layer, made of plastic, provides effective heat insulation by creating a space between its walls

Methodology Applied
Scientific EffectThermal Insulation: Thermal Insulation

Data Source

PatentEP3347608B1Ball joint comprising a protective cap and two-point linkage comprising a ball joint of this type
Publication Date: 2019.09.25 ZF FRIEDRICHSHAFEN AG
  • EP3347608B1 patent drawingFigure 1
  • EP3347608B1 patent drawingFigure 2
  • EP3347608B1 patent drawingFigure 3

AI summary

Disclosed is a protective cap (1, 20) for covering some sections of a ball-joint (30) mounting assembly, the protective cap (1, 20) having a wall (2, 22) that is suitable for enclosing a region of the ball joint (30) that is to be covered. The protective cap (1, 20) is characterised in that it has at least one auxiliary wall (3, 21) at a distance from the wall (2, 22) for protecting some regions of the ball joint (30) against heat damage. Also disclosed is a ball joint (30) comprising a bellows seal (31), at least some regions of which bellows seal (31) are protected against heat damage, in particular radiant heat, by the double-walled region (4, 27) of said protective cap (1, 20). The invention further relates to a two-point linkage (40), in particular for a utility vehicle, which two-point linkage (40) is characterised in that it has a connecting tube (41), at least one end section (42) of which is connected to a ball joint (30) of the aforementioned type.