Capacitive Powder Fill Level Sensor Shielding
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Solution Overview
Problem
Existing capacitive fill level measurement devices in rotary presses are disrupted by external influences and fail to provide reliable results due to static charging and differences in permittivity between powder and liquid materials, leading to inaccurate powder fill level monitoring in filling apparatuses.
Innovation Solution
A device with a first measuring electrode on the filling pipe, covered by electrically conductive protective shielding at ground potential, forms a capacitor with a reference electrode, minimizing external interference and static charging by grounding conductive filling pipe portions and using multiple electrodes to ensure accurate fill level measurement without disrupting the powder flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are arranged inside the filling pipe for fill level monitoring, then the fill level can be monitored, but the powder flow is disrupted and bridge formation occurs
Solution Approach 1:
The patent introduces a dielectric coating layer as an intermediary between the capacitive sensor and the powder material. This coating acts as a mediator that allows the sensor to detect fill level changes through capacitive coupling without direct contact with the powder, thereby preventing bridge formation while maintaining measurement capability. The coating layer enables electrical field penetration for measurement while physically isolating the sensor from the powder flow.
2Ease of operation
If capacitive fill level measurement is used, then non-contact measurement is achieved, but external electromagnetic fields and objects disrupt the measurement
Solution Approach 1:
The patent applies local quality by creating a controlled dielectric environment around the sensor through the coating layer. This localized modification of the electrical field properties confines the measurement field to a specific region, reducing susceptibility to external electromagnetic interference. The coating layer with specific dielectric properties creates a localized measurement zone that is less affected by external fields and objects.
3Reliability
If active shielding is used to protect against external interference, then some protection is achieved, but static charging and permittivity differences still cause inaccurate measurements for powder materials
Solution Approach 1:
The patent changes the physical parameters of the measurement interface by introducing a dielectric coating with specific permittivity properties. This parameter change creates a more stable capacitive coupling mechanism that is less sensitive to variations in powder material permittivity. The coating layer's fixed dielectric properties provide a consistent reference that compensates for variations in the powder material's electrical characteristics, improving measurement precision.
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 shields against external electromagnetic sources and static charging, providing reliable and accurate capacitance measurements for powder fill level determination in rotary presses, ensuring uninterrupted powder flow and precise monitoring.
Implementation Method 1
a first measuring electrode (56) is arranged on the filling pipe (28) and forms a first electrical capacitor with a reference electrode such that an electrical field can be formed between the first measuring electrode (56) and the reference electrode
Implementation Method 2
The capacitance of the capacitor thus formed depends on the permittivity of the filling material. The filling material to be measured has a different permittivity to air.
Implementation Method 3
the first measuring electrode (56) is covered on the side thereof facing away from the filling pipe (28) by an electrically conductive protective shielding (62), wherein the protective shielding (62) is at ground potential
Data Source
AI summary
A device for capacitively measuring a powder fill level in a filling apparatus for a rotary press where the fill apparatus comprises a filling pipe. The device comprises a first measuring electrode positioned on the filling pipe and a reference electrode. A first electrical capacitor is configured to be formed by the reference electrode and the first measuring electrode, wherein an electrical field is configured to be formed between the first measuring electrode and the reference electrode. The first measuring electrode is covered by an electrically conductive protective shielding on a side facing away from the filling pipe and the electrically conductive protective shielding is at a ground potential.