Angled Restriction Element for Pressure Sensor Diaphragm Protection

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Solution Overview

Problem

Pressure sensors in flow systems are prone to damage from cavitations, pressure peaks, and start-up liquid jets, which can damage the sealing and measuring diaphragms, and existing solutions for protection are complex, costly, and difficult to mount securely.

Innovation Solution

A restriction element integrated with the weld support element forms a damping chamber in front of the sealing diaphragm, protecting it from damage by cavitations and pressure peaks, and is designed to be easy to manufacture and mount, with a nozzle oriented away from the diaphragm to prevent direct liquid impact during start-up.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a straight nozzle hole is used to protect the sealing diaphragm from pressure peaks, then the diaphragm is protected from cavitations, but the nozzle must be placed at a relatively long distance from the diaphragm which increases the risk of damage from start-up liquid jets

Engineering Contradiction:

Improveprotection from cavitationsVSAvoiddamage from start-up liquid jets

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetry by orienting the nozzle hole at an angle between 45 and 135 degrees relative to the sealing diaphragm surface, rather than perpendicular to it. This asymmetric orientation allows the nozzle to be positioned closer to the diaphragm while still providing cavitation protection, as the angled jet direction reduces the risk of direct liquid jet impact on the diaphragm during start-up conditions.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent implements preliminary action by pre-positioning the nozzle at an optimized angle and distance from the sealing diaphragm during manufacturing. This preliminary configuration ensures that when the pressure sensor is put into service, the protective effect is immediately active without requiring additional adjustment or setup, and the angled orientation is already in place to deflect start-up liquid jets away from the diaphragm.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a restriction element is placed in the fluid inlet channel, then the sealing diaphragm is protected from pressure peaks, but the restriction element becomes difficult to mount securely and may fall out

Engineering Contradiction:

Improveprotection from pressure peaksVSAvoidmounting security

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies merging by integrating the restriction element directly into the pressure element housing as a fixed, permanent component rather than a separate removable part. The restriction element is formed as an integral part of the pressure element, eliminating the need for separate mounting operations and ensuring it cannot fall out or become dislodged during operation, while still providing the necessary cavitation and pressure peak protection.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If the nozzle is oriented perpendicular to the sealing diaphragm, then the restriction element effectively filters pressure peaks, but direct liquid jets during start-up can damage the diaphragm

Engineering Contradiction:

Improvepressure peak filteringVSAvoiddirect liquid jet damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #4Asymmetry

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 effectively prevents damage from pressure changes and liquid jets, ensuring the sealing diaphragm's integrity and simplifying the assembly and production process, while maintaining a high pressure sensing bandwidth.

Implementation Method 1

The restriction element is forming a damping chamber in front of the sealing diaphragm, protecting the sealing diaphragm from damage in case of big pressure changes occurs

Methodology Applied

Scientific EffectDamping: Damping

Implementation Method 2

A sealing diaphragm (5) covers a recess (23) in the housing part (19) to provide a substantially closed cavity (9). The closed cavity (9) is filled with a sealing media typically oil to transfer the pressure from the sealing diaphragm to the measuring diaphragm

Methodology Applied

Scientific EffectPressure transfer: Pressure Gradient

Data Source

PatentEP2089684B1A pressure sensor

Publication Date: 2010.06.09 DANFOSS AS

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Figure 5

AI summary

The invention provides a restriction element for a pressure sensor to protect the pressure element from flow related damage. The pressure sensor comprising a housing with a fluid inlet channel and a chamber with a pressure element. The pressure element comprises a housing part with a recess covered by a sealing diaphragm forming a cavity. In the oil-filled cavity a sensor element is placed. The restriction element is placed in front of the sealing diaphragm protecting the pressure element and especially the sealing diaphragm from a damaging pulse or other flow related damages caused by sudden changes in a flow system for example by closing a valve.