Pressure Sensor Membrane Protection Using Damping Elastomer
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Solution Overview
Problem
Pressure sensors in hydraulic flow systems are prone to damage from sudden fluid flow changes, such as cavitation and pressure peaks, which can cause damage to sealing and measuring membranes, necessitating effective pressure attenuation solutions.
Innovation Solution
A pressure sensor arrangement utilizing a homogeneous incompressible material with a mechanical loss factor of 0.10 or higher at frequencies above 200 Hz, preferably an elastomer like Wacker Elastosil LR 3003, is placed in direct contact with the membrane to attenuate pressure pulses, providing protection across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure attenuation means are arranged in the fluid chamber in direct contact with the membrane, then pressure spikes and vibrations are attenuated effectively, but the device complexity increases
Solution Approach 1:
The patent employs a porous damper material arranged in the fluid chamber in direct contact with the membrane. The porous structure provides pressure attenuation through its inherent damping properties while maintaining fluid flow capability. The porosity allows the material to absorb pressure spikes and vibrations effectively without blocking the fluid path, thus protecting the membrane while adding minimal structural complexity.
Solution Approach 2:
The damper material acts as an intermediary element between the fluid and the membrane. It mediates the interaction by absorbing excessive pressure and vibrations before they reach the membrane, thereby protecting the membrane from damage. This intermediary approach allows the system to maintain its functional integrity while adding a protective layer that does not significantly complicate the overall device structure.
2Reliability
If a homogeneous incompressible material with high mechanical loss factor is used, then pressure pulse attenuation is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a porous damper material with particular attention to its porous structure characteristics. The porous nature provides inherent damping properties through the mechanical loss factor while being relatively tolerant to manufacturing variations. The porosity allows the material to maintain its attenuation function even with moderate manufacturing tolerances, reducing the stringency of precision requirements compared to dense homogeneous materials.
Solution Approach 2:
The patent focuses on the mechanical loss factor as a key parameter for selecting the damper material. By specifying a minimum mechanical loss factor (0.10 or higher at 200 Hz), the patent establishes a performance threshold rather than requiring exact dimensional precision. This parameter-based specification approach allows for material selection based on functional performance rather than strict manufacturing tolerances, thereby reducing manufacturing precision requirements.
3Reliability
If the pressure attenuation means are placed in direct contact with the membrane, then the protection effectiveness is improved, but the risk of material degradation increases
Solution Approach 1:
The porous structure of the damper material provides inherent resistance to material degradation. The porous network distributes mechanical stresses throughout the material volume, preventing stress concentration that could lead to degradation. Additionally, the porous structure allows for better energy dissipation through friction and viscous effects within the pores, reducing the cumulative damage from pressure cycles and extending the material's service life.
Solution Approach 2:
The damper material is designed as a consumable or replaceable component with a designed service life. Rather than attempting to create an indefinitely durable material, the patent accepts that the damper will degrade over time and can be replaced. This approach allows the use of simpler, more cost-effective materials that provide excellent pressure attenuation during their service life, while the replacement strategy manages the long-term reliability without requiring overly complex or expensive durable materials.
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 attenuates pressure spikes and vibrations, protecting the membranes from damage caused by sudden pressure changes, ensuring reliable operation across varying frequencies and temperatures.
Implementation Method 1
pressure attenuation means arranged in the fluid chamber in direct contact with the membrane separating the membrane from the fluid in the fluid chamber and comprise a homogenous incompressible material having a mechanical loss factor of 0.10 or higher at frequencies of 200 Hz or higher
Implementation Method 2
The loss factor which is also termed 'loss angle' or 'loss tangent' is a signature of the damping properties of an incompressible material
Data Source
AI summary
A pressure sensor arrangement (1) for measuring a pressure of a fluid is described, the sensor arrangement (1) comprising a connector housing (2) having a fluid opening (3) and a fluid chamber (4) in connection with the fluid opening (3), at least one pressure sensitive element (5), a membrane (9) arranged between the pressure sensitive element (5) and the fluid chamber (4), and pressure attenuation means (10). Such a pressure sensor arrangement should be able to protect the measuring membrane from high frequency pressure pulsations with low costs. To this end the pressure attenuation means (10) are arranged in the fluid chamber (4) in direct contact with the membrane (9) separating the membrane (9) from the fluid in the fluid chamber and comprise a homogenous incompressible material having a mechanical loss factor of 0.1 or higher at frequencies of 200 Hz or higher.