Vibrating Membrane Sensor Harmonic Mode Decoupling
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Solution Overview
Problem
Existing vibration measuring devices face challenges in accurately detecting process variables, particularly for liquids and bulk materials, due to energy loss and limited applicability in small containers, and they often require a non-flush installation which complicates cleaning and operation in industries like food and pharmaceuticals.
Innovation Solution
A vibration measuring device with a mechanically decoupled membrane oscillator that excites harmonic oscillations above the fundamental mode, using a piezoelectric drive/receiver unit and a clamping system to prevent energy transfer to the container, allowing for flush installation and efficient detection of process variables like fill level, viscosity, and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the membrane is mechanically coupled to the container for support, then the membrane can be held in position, but energy is lost through coupling to the container
Solution Approach 1:
The patent introduces a resilient element as an intermediary between the membrane and the container. This resilient element mechanically decouples the membrane from the container, allowing the membrane to be held in position while preventing energy loss through coupling to the container. The resilient element acts as a mediator that supports the membrane without creating rigid mechanical connections that would cause energy dissipation.
2Measurement precision
If the effective mass of the oscillatable unit is reduced, then the response to medium contact is improved, but the structural integrity and detection reliability may be compromised
Solution Approach 1:
The patent changes the physical parameters of the membrane by using a resilient element with specific elastic properties. This allows the membrane to maintain sufficient structural integrity and detection reliability while having reduced effective mass. The parameter changes in the resilient element's material properties and geometry enable the membrane to be sufficiently light for sensitive detection while remaining reliable through proper mechanical design.
3Ease of operation
If a flush-front design is implemented with a single membrane, then cleaning is easier and process advantages are gained, but mechanical coupling with the process connection occurs
Solution Approach 1:
The resilient element serves as a mechanical intermediary that decouples the membrane from the process connection while maintaining the flush-front design. This allows the membrane to be positioned flush with the container wall for easy cleaning and process advantages, while the resilient element prevents direct mechanical coupling that would cause energy loss. The intermediary element bridges the gap between the design requirements and energy conservation needs.
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 device provides reliable and energy-efficient detection of process variables with minimal energy loss, enabling flush installation and easier cleaning, suitable for various industrial applications, including the food and pharmaceutical industries.
Implementation Method 1
with at least one piezoelectric drive/receiver unit which is attached to the membrane and which generates mechanical vibrations of the membrane and/or which receives mechanical vibrations from the membrane
Implementation Method 2
the membrane only carries out mechanical oscillations which correspond to modes that are above the basic mode of the membrane
Implementation Method 3
The fact that the characteristics of the oscillations (oscillation amplitude, resonance frequency, phase response over frequency) of the oscillating unit depend on the contact with the medium
Data Source
AI summary
The invention relates to a device for determining and/or monitoring at least one process variable of a medium. Said device comprises at least one mechanically vibrating membrane (1) that has a plurality of natural intrinsic modes, and at least one excitation/reception unit (2) which excites the membrane (1) to perform mechanical vibrations and/or receives mechanical vibrations from the membrane (1). According to the invention, the excitation/reception unit (2) and the membrane (1) are designed and adjusted to one another in such a way that the membrane (1) performs only mechanical vibrations which correspond to modes lying above the fundamental mode of the membrane (1).