Piezoelectric Sensor for Density Viscosity Measurement
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Solution Overview
Problem
Existing density and viscosity sensors face accuracy issues due to interference from stationary acoustic waves created by the membrane, particularly in harsh environments.
Innovation Solution
A density and viscosity sensor design featuring a piezoelectric element with a single conductive area and multiple conductive areas of opposite electrical potential, positioned to minimize interference by controlling the vibration mode of the resonating element, allowing for accurate measurements without parasitic acoustic waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a membrane is used to separate the chamber from the fluid and transfer mechanical vibration, then the sensor can be isolated from the fluid in harsh environments, but the membrane creates stationary acoustic waves that interfere with measurements
Solution Approach 1:
The patent applies the 'Blessing in disguise' principle by using the membrane's vibration capability for beneficial purposes. Instead of allowing the membrane to create harmful stationary acoustic waves, the invention drives the membrane to vibrate at specific resonant frequencies that cancel out the harmful stationary waves, thereby converting the harmful acoustic interference into a beneficial cancellation effect that improves measurement accuracy
2Power
If the piezoelectric element uses traditional conductive areas configuration, then it can provide sufficient actuating force, but it generates stationary acoustic waves that interfere with measurements
Solution Approach 1:
The patent applies the 'Segmentation' principle by dividing the piezoelectric element's conductive areas into multiple separate regions with different polarizations. Instead of using a single uniform conductive area, the invention segments the electrode into multiple zones that can be independently controlled, allowing different segments to generate vibrations in opposite phases that cancel out harmful stationary acoustic waves while maintaining sufficient actuating force
Solution Approach 2:
The patent applies the 'Asymmetry' principle by creating an asymmetric configuration of conductive areas with different polarizations on the piezoelectric element. This asymmetric arrangement allows the different regions to expand and contract in opposite directions, generating counter-phase vibrations that eliminate stationary acoustic wave interference while preserving the necessary actuating power
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 sensor provides reliable and accurate measurements by canceling out stationary acoustic wave interference, ensuring robust performance in harsh environments and reducing the impact of uncontrolled electrical potentials.
Implementation Method 1
the actuating/detecting element comprises at least one piezoelectric element comprising two sides substantially parallel to the membrane; one side of the piezoelectric element comprises a single conductive area; and another side of the piezoelectric element comprises at least two conductive areas isolated from each other, each conductive area being coupled to an electrical potential of opposite sign relatively to adjacent areas such that the resonating element is driven to vibrate
Implementation Method 2
a resonating element arranged to be immersed in the fluid and mechanically coupled to the membrane
Data Source
AI summary
A density and viscosity sensor for measuring density and viscosity of a fluid, comprises:a housing (4) defining a chamber (8) isolated from the fluid (3), the housing (4) comprising an area defining a membrane (9) separating the chamber (8) from the fluid (3);a resonating element (5) arranged to be immersed in the fluid (3) and mechanically coupled to the membrane (9); andan actuating/detecting element (6) coupled to the resonating element (5), the actuating/detecting element (6) being positioned within the chamber (8) and mechanically coupled to the membrane (9), the actuating/detecting element (6) comprising at least one piezoelectric element (10) comprising two sides (11, 12) substantially parallel to the membrane (9);The membrane (9) has a thickness enabling transfer of mechanical vibration between the actuating/detecting element (6) and the resonating element (5).One side (11) of the piezoelectric element (10) comprises a single conductive area (13).Another side (12) of the piezoelectric element (10) comprises at least two conductive areas (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H) isolated from each other, each conductive area (14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H) being coupled to an electrical potential (V1, V2) of opposite sign relatively to adjacent areas such that the resonating element (5) is driven to vibrate in a selected plane (P1, P2) perpendicular to the membrane (9).