Piezoelectric Inchworm Compensation for Oscillating Fill Level Sensors
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Solution Overview
Problem
Existing fill level measuring devices with oscillating systems are complex to manufacture and require uncomfortable manual adjustment or complex motor control for calibration, especially when dealing with build-up and corrosion, which affects the accuracy of fill level measurements.
Innovation Solution
A fill level measuring device with a compensation device made of piezoelectric materials, featuring a first and second locking element and a coupling element, which adjusts the mass moment of inertia using the inchworm principle for precise positioning, allowing automatic compensation for imbalances caused by build-up or corrosion, without the need for manual intervention or motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a compensation device with piezoelectric materials and inchworm principle is used, then positioning precision and automatic adjustment capability are improved, but device complexity increases
Solution Approach 1:
The patent replaces traditional mechanical adjustment mechanisms (manual screw adjustment or motor control) with a piezoelectric-based inchworm mechanism. The piezoelectric materials convert electrical signals directly into mechanical displacement, enabling automatic positioning of the compensation mass without complex mechanical linkages or motors, thus improving precision while managing complexity through direct electro-mechanical conversion.
Solution Approach 2:
The compensation device automatically adjusts the compensation mass position in response to detected imbalances in the oscillating system. The electronic unit monitors the oscillation characteristics and triggers the piezoelectric actuators to reposition the mass, enabling self-compensation without external manual intervention, thereby maintaining high measurement accuracy autonomously.
2Device complexity
If manual adjustment of calibration body is used, then device complexity is reduced, but ease of operation deteriorates
Solution Approach 1:
The system automatically performs calibration by monitoring oscillation frequency and amplitude changes caused by build-up or corrosion. The electronic unit calculates the required compensation mass position and actuates the piezoelectric elements accordingly, eliminating the need for manual calibration operations while maintaining simple device architecture.
Solution Approach 2:
The electronic unit continuously monitors the oscillation characteristics of the dual-element system and uses this feedback to determine when compensation is needed. Based on the detected changes in resonant frequency or damping, the system automatically adjusts the compensation mass position, providing closed-loop control that simplifies operation while maintaining accuracy.
3Ease of operation
If motor control is used for calibration, then ease of operation is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent substitutes motor-driven mechanical adjustment with a piezoelectric inchworm mechanism. The piezoelectric materials provide direct electromagnetic-to-mechanical conversion with no moving parts, eliminating motors, gearboxes, and associated control electronics. This reduces device complexity and manufacturing cost while maintaining automatic calibration capability through precise electrical control of the piezoelectric elements.
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
Enables high-accuracy fill level measurements by automatically adjusting the oscillating system to maintain optimal vibration amplitude and frequency, ensuring reliable operation without wear and reducing the complexity of manufacturing and calibration processes.
Implementation Method 1
The locking elements and the coupling element are made of a piezoelectric material, the coupling element connects the first locking element and the second locking element to one another
Implementation Method 2
Both oscillating rods are each fastened to a common carrier via an elastic holding part and are excited to transversal oscillations in opposite directions at the natural resonant frequency of the oscillating system
Data Source
Figure 1
Figure 2a~2d
AI summary
The invention relates to a fill level measuring device (1) having an oscillating system (2) comprising at least one outer tubular oscillating element (21) and an inner oscillating element (22), wherein the outer oscillating element (21) coaxially surrounds the inner oscillating element (22), at least in sections. The invention is characterized in that a compensation device (3) that can be moved in an axial direction is arranged in an inner chamber of the inner oscillating element (22), which compensation device comprises at least one first locking element (31), a second locking element (32), and a coupling element (33). The locking elements (31, 32) and the coupling element (33) are made of a piezoelectric material, wherein the coupling element (33) connects the first locking device (31) and the second locking device (32) with one another. In an idle mode, the first locking device (31) and the second locking device (32) are each force-fittedly connected to a wall of the inner chamber. The fill level measuring device is provided with an electronic unit (6) configured to position the compensation device (3) in a predeterminable position by way of electric signals.