Piezoelectric Density Sensor Clamping Element Design
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Solution Overview
Problem
Existing density measuring devices for fluid media using flexural resonators face issues with sensitivity and thermal time constant due to the mass and thermal capacity of excitation and sensor devices, which can influence the oscillating system and lead to signal cross-talk and undesirable oscillation modes.
Innovation Solution
A density measuring device with a hollow body featuring parallel tube sections and a clamping element, where piezoelectric elements for excitation and sensing are attached to the clamping element, reducing mass influence and enhancing symmetry, resulting in improved sensitivity and thermal compensation, and eliminating the need for magnetic coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnet systems are used as excitation and sensor devices directly attached to the oscillating tubes, then the density measurement function is achieved, but the mass and thermal capacity of these devices adversely influence the oscillating system, reducing sensitivity and increasing thermal time constant
Solution Approach 1:
The patent extracts the excitation and sensor devices from direct attachment to the oscillating tubes. Instead, piezoelectric elements are attached to a clamping element that holds the tubes, separating the measurement function from the oscillating mass. This reduces the mass and thermal capacity influencing the oscillation, improving sensitivity and thermal response time while maintaining density measurement capability through detection of oscillation parameter changes.
Solution Approach 2:
The clamping element serves as an intermediary structure between the piezoelectric elements and the oscillating tubes. The piezoelectric elements attach to the clamping element rather than directly to the tubes, allowing excitation and sensing without adding significant mass to the oscillating system. This mediator approach enables the measurement function while minimizing adverse influence on oscillation characteristics.
2Measurement precision
If magnet systems with coils are used for excitation and sensing, then density measurement is enabled, but signal cross-talk and excitation of undesirable oscillation modes occur, affecting measurement reliability
Solution Approach 1:
The patent replaces magnetic coil systems with piezoelectric elements for both excitation and sensing functions. Piezoelectric elements directly couple mechanical vibration to electrical signals without involving magnetic fields, eliminating signal cross-talk between excitation and sensor coils. This substitution improves measurement reliability by preventing excitation of undesirable oscillation modes while maintaining the ability to detect density-related oscillation parameter changes.
3Measurement precision
If excitation and sensor devices are directly attached to the oscillating tubes, then the density measurement function is achieved, but the device complexity increases due to additional components and attachment requirements
Solution Approach 1:
The patent merges the excitation and sensor devices onto a single clamping element structure. Both piezoelectric elements are attached to the same clamping element that holds the oscillating tubes, simplifying the overall device architecture. This integration reduces the number of separate components and attachment points compared to direct tube attachment, lowering manufacturing complexity while maintaining measurement functionality.
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 design enhances sensitivity and reduces thermal time constant, minimizing external oscillation effects and making the device more lightweight and cost-effective while maintaining high accuracy in density measurements.
Implementation Method 1
An excitation device including a piezoelectric element for exciting an oscillation of the tube sections
Implementation Method 2
a sensor device including a piezoelectric element for detecting a variable characterizing an excited vibration
Implementation Method 3
Density measurement of fluid media using a flexural resonator is based on the fact that the natural oscillations of a tube filled with the fluid medium change with the density of the medium
Data Source
AI summary
A density measuring device has a hollow body (1) for receiving a fluid medium. The hollow body includes at least two parallel tube sections (6, 6a, 7, 7a) with a connecting line (9) on a first end thereof that connects the tube sections in a U shape. On a second end, the hollow body has a clamping element (2) with a clamping tube (5, 5a) terminating each of the tube sections. An excitation device including a piezoelectric element (4) oscillates the tube sections and a sensor device, also with a piezoelectric element (4a), detects a variable characterizing an excited vibration. Both piezoelectric elements are attached to a contact area (3, 3a) of the clamping element. The contact areas are disposed on the proximal end of the clamping element relative to the tube sections. Each contact area extends across both clamping tubes.