Angled Mating Surfaces in Valve Assemblies

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Solution Overview

Problem

Conventional valve assemblies face limitations in maximizing clamping force without causing plastic deformation, as the compressive force acting normal to the mating surfaces restricts the maximum allowable force, leading to potential leakage and reduced service life.

Innovation Solution

The valve assembly design incorporates a circumferential mating protrusion with angled upper and lower surfaces, allowing both longitudinal and transverse force components to act on the mating surfaces, increasing the resultant clamping force beyond the yield force while preventing plastic deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If planar mating surfaces are used in conventional valve assemblies, then the structure is simple and easy to manufacture, but the maximum allowable clamping force is limited to below the yield force to prevent plastic deformation

Engineering Contradiction:
Improveclamping forceVSAvoidmaterial yield strength
Core Design Contradiction:
ForceVSStrength

Solution Approach 1:

The patent changes the geometric parameters of the mating surfaces from planar to angled surfaces. The upper and lower mating surfaces are inclined at angles (e.g., 15-45 degrees) relative to the transverse plane, which transforms the force distribution. This parameter change allows the clamping force to be resolved into longitudinal and transverse components, enabling the resultant force to exceed the material yield strength while preventing plastic deformation through proper angle selection.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a new dimension to the force application by inclining the mating surfaces. Instead of applying force purely in the longitudinal direction (one dimension), the angled surfaces create force components in both longitudinal and transverse directions (two dimensions). This dimensional change allows the clamping force to be distributed more effectively, increasing the safe working load while maintaining structural integrity.

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

2Force

If planar mating surfaces are used, then the design is straightforward, but the number of bolts required is high to achieve adequate clamping force

Engineering Contradiction:
Improveclamping forceVSAvoidnumber of bolts
Core Design Contradiction:
ForceVSQuantity of substance

Solution Approach 1:

By changing the mating surface geometry from planar to angled, the patent increases the mechanical efficiency of each bolt. The angled surfaces create a wedge effect that amplifies the clamping force generated by each bolt, reducing the total number of bolts needed to achieve the required overall clamping force on the valve cage.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If planar mating surfaces are used, then the assembly is simple, but sealing performance deteriorates under thermal expansion conditions

Engineering Contradiction:
Improvesealing performanceVSAvoidthermal expansion
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The angled mating surfaces introduce a geometric configuration that accommodates thermal expansion in multiple directions. When thermal expansion occurs, the inclined surfaces allow for controlled movement and redistribution of contact pressures, maintaining sealing effectiveness whereas planar surfaces would concentrate stresses and potentially compromise the seal.

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

Data Source

PatentEP2817546B1Oblique mating surfaces in a valve assembly
Publication Date: 2017.05.10 FISHER CONTROLS INT LLC
  • EP2817546B1 patent drawingFigure 1
  • EP2817546B1 patent drawingFigure 2
  • EP2817546B1 patent drawingFigure 3~4

AI summary

A valve assembly includes a valve body having a body recess and a bonnet including a bonnet recess having a bonnet mating surface. The valve assembly further includes a valve cage disposed within an interior of the valve body, the valve cage including a body portion extending along a longitudinal axis and a circumferential mating protrusion extending from an outer surface in a transverse direction, the mating protrusion including an upper mating surface and a lower mating surface. The upper mating surface is disposed within the bonnet recess to be aligned with the bonnet mating surface, and the lower mating surface is disposed within the body recess to be aligned with the body mating surface, wherein the upper and lower mating surface are not parallel. Accordingly, clamping forces acting on the mating protrusion include a longitudinal and tangential component, allowing for increased clamping forces without plastically deforming the mating protrusion.