Housing Cover Disk Assembly With Elastomer Ring Retention

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Solution Overview

Problem

Existing housing cover assemblies for field devices, particularly those requiring Ex-d or 'flameproof enclosure' protection, have complex designs and strict manufacturing tolerances, making them difficult to assemble efficiently without compromising performance.

Innovation Solution

A simplified assembly comprising a circular disk, a ring body with an elastomeric ring that is clamped between convex shoulders, providing a seal and absorbing impact energy, thus relieving the load on the disk and ensuring secure retention without complex locking mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If complex designs with metallic retaining rings and strict manufacturing tolerances are used, then the Ex-d protection class is achieved, but the assembly complexity and manufacturing difficulty increase

Engineering Contradiction:
ImproveEx-d protection classVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into a single elastomer ring component: sealing, impact absorption, and disk retention. This replaces the traditional complex assembly of metallic retaining rings, sealing rings, and precision-machined features, achieving Ex-d protection without the associated complexity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The elastomer ring serves multiple purposes simultaneously: it provides the seal between the circular disk and housing, absorbs impact energy through its elastic properties, and retains the circular disk in position. This multi-functional design eliminates the need for separate components for each function

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

2Reliability

If complex designs with multiple sealing rings and retaining mechanisms are used, then the required protection class is achieved, but the number of components and assembly steps increase

Engineering Contradiction:
Improveprotection classVSAvoidassembly efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

Multiple components (sealing ring, retaining ring, impact absorber) are merged into a single elastomer ring component, reducing the number of parts to be manufactured, stored, and assembled. This directly improves assembly efficiency while maintaining protection class

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The elastomer ring's elastic properties enable it to self-adjust and self-seal under varying conditions, eliminating the need for complex adjustment mechanisms and precision assembly procedures, thereby simplifying the assembly process

Inventive Principle:
Principle #25Self-service

3Strength

If rigid retaining mechanisms are used, then the circular disk is securely held, but stress concentration and potential damage during impacts occur

Engineering Contradiction:
Improveretention strengthVSAvoidimpact stress
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent changes the mechanical parameters of the retention system by using an elastomer ring with specific elastic moduli and damping characteristics. This allows the system to maintain retention strength while dynamically absorbing impact energy, preventing stress concentration on the circular disk

Inventive Principle:
Principle #35Parameter changes

4Reliability

If multiple separate sealing components are used, then the seal is reliable, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvesealing reliabilityVSAvoidtolerance requirements
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

Multiple sealing functions are combined into the elastomer ring, which inherently provides sealing through its elastic deformation and conformability to mating surfaces. This eliminates the need for multiple precision-machined sealing surfaces and separate sealing components

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The elastomer ring acts as a flexible sealing element that deforms to accommodate surface irregularities and maintain sealing under varying conditions, reducing the need for high manufacturing precision on mating surfaces while maintaining sealing reliability

Inventive Principle:
Principle #30Flexible shells and thin films

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

The solution enables a simplified assembly process while maintaining the required protection standards, absorbing impact energy and ensuring secure sealing, thus meeting the Ex-d protection class without the need for complex designs or high manufacturing tolerances.

Implementation Method 1

The elastic mounting in an elastomer ring also allows for the absorption of impact energy, thus significantly relieving the disc of stress during impacts.

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

an additional sealing ring being provided which rests against the circular disk to prevent gas exchange past the circular disk between two volumes separated from each other by the circular disk

Methodology Applied
Scientific EffectElastic sealing: Elasticity

Data Source

PatentEP4077984B1Assembly, housing cover having an assembly of this type, and field device having a housing cover of this type
Publication Date: 2024.05.22 ENDRESS HAUSER FLOWTEC AG
  • EP4077984B1 patent drawingFigure 1~2

AI summary

The invention relates to an assembly (100) comprising: a circular disk (160); an annular body (110); and an elastomer ring (190). The annular body (110) has a disk receptacle (120), which is surrounded by a peripheral lateral surface, the lateral surface having an annular outer groove (130), which is delimited in a first axial direction by a first outer shoulder (132) and in an opposite, second axial direction by a second axial outer shoulder (134). A guide surface adjoins the first outer shoulder in the first axial direction, the radius of which guide surface monotonically increases as the distance from the first shoulder increases, and in the case of which guide surface dr/dz is less than 2/3, in particular less than 1/3, r being the radius and z being the axial coordinate of the guide surface in cylindrical coordinates. The circular disk (160) has an outer lateral surface having a peripheral inner groove (170), which extends radially inward and is delimited in the first axial direction by a first inner shoulder (172) and in the second axial direction by a second inner shoulder (174). When seen in an axial longitudinal section in which the axis of rotation of the circular disk (160) runs, at least the two inner shoulders have a convex contour. The elastomer ring (190) is clamped between both inner shoulders and both outer shoulders, and in particular sliding of the circular disk out of the annular body is thereby prevented up to a limit load.