Radial Shaft Seal Plastic Insert Centric Assembly

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Solution Overview

Problem

Radial shaft sealing rings often get damaged during assembly, especially when dealing with shafts having multiple teeth and in tight spaces, where existing assembly aids cannot be used effectively.

Innovation Solution

A plastic ring insert is integrated into the radial shaft sealing ring to serve as an assembly aid, remaining on the sealing ring post-assembly, ensuring centric alignment and preventing damage, with features like a bead for drainage and a form-fitting connection to the sealing ring or its support body.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protective ring with axial movement is used during assembly, then the sealing lip is protected from damage, but the device complexity increases and axial space is required

Engineering Contradiction:
Improvesealing lip protectionVSAvoidassembly aid structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the protective function with the sealing ring itself by integrating a protective cap made of elastomeric material directly into the sealing ring structure. The cap is permanently attached to the sealing lip carrier and moves axially together with the sealing ring during assembly, eliminating the need for separate protective devices while maintaining protection functionality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The sealing ring is designed to serve multiple functions: it provides sealing action through its lips, structural support through the sealing lip carrier, and protection during assembly through the integrated cap. The cap itself serves dual purposes by protecting the sealing lip during assembly while also being part of the functional sealing structure during operation.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If a protective ring with axial movement is used during assembly, then the sealing lip is protected from damage, but the available axial space must be sufficient

Engineering Contradiction:
Improvesealing lip protectionVSAvoidaxial space requirement
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

By merging the protective cap with the sealing ring structure, the patent eliminates the need for additional axial space that would be required for separate protective devices. The cap moves axially within the existing dimensions of the sealing ring assembly, making the solution applicable even in tight spaces with limited axial movement capability.

Inventive Principle:
Principle #5Merging (Combining)

3Manufacturing precision

If the ring insert is placed close to the shaft for alignment, then centric alignment is achieved, but the ring insert may contact the shaft during operation

Engineering Contradiction:
Improvecentric alignmentVSAvoidring insert contact with shaft
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the alignment function from the protective cap by providing a separate alignment aid in the form of a projection on the sealing ring that engages with a corresponding recess on the shaft. This allows the cap to be positioned close to the shaft for alignment purposes while the dedicated alignment projection ensures precise centric positioning without the cap interfering with shaft rotation during operation.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP1921355B1Lip seal
Publication Date: 2013.02.27 CARL FREUDENBERG KG
  • EP1921355B1 patent drawingFigure 1
  • EP1921355B1 patent drawingFigure 2

AI summary

The radial shaft sealing ring comprises an elastomer sealing component with at least one sealing lip and a support component, wherein the sealing ring (1) has an annular insert (19) consisting of plastic which is arranged on the inner side (22) of the support component (6), and the inside diameter of which is greater than the outside diameter of the shaft (5) which is encompassed by the sealing ring. The sealing lip is pressed onto the shaft by an annular helical spring.