Capacitive Flow Detection Circuit for Beverage Dispensing
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Solution Overview
Problem
Existing flow detection systems for beverage dispensing systems are inefficient due to the use of bulky and expensive inductances, requiring significant circuitry for frequency-to-voltage conversion, and lack simplicity in signal processing.
Innovation Solution
A flow detection circuit using capacitive sensors with alternating signal sources, capacitive elements, and processing circuits that detect signal amplitude, allowing implementation in analogue, digital, or hybrid domains, reducing complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inductance is used for capacitive flow measurement, then frequency detection is achieved, but device complexity and cost increase due to bulky inductances and significant circuitry requirements
Solution Approach 1:
The patent extracts and eliminates the inductance component from the measurement circuit, replacing the traditional capacitive-to-frequency conversion method with a direct capacitive measurement approach. This removes the bulky inductance and associated complex circuitry while maintaining flow detection capability through direct capacitance sensing of the liquid medium.
Solution Approach 2:
The patent substitutes the mechanical/electromagnetic inductance-based frequency conversion system with a direct electrical capacitance measurement system. By measuring capacitance changes directly caused by liquid presence and flow characteristics, the system eliminates the need for inductive components and complex frequency-to-voltage conversion circuitry.
2Measurement precision
If inductance and frequency conversion circuitry are used, then flow measurement is achieved, but manufacturing cost increases
Solution Approach 1:
The patent removes expensive inductance components and complex frequency conversion circuitry from the manufacturing bill of materials. The simplified capacitive sensing circuit requires fewer components, reducing both component costs and assembly complexity, thereby lowering overall manufacturing costs while maintaining measurement accuracy.
Solution Approach 2:
The patent changes the measurement parameter from frequency (requiring inductance) to direct capacitance measurement. This parameter change enables the use of simpler, cheaper capacitive sensing circuits that do not require expensive inductive components or complex frequency conversion hardware, thus reducing manufacturing costs.
3Loss of information
If frequency variation method is used for flow detection, then flow information is obtained, but signal processing complexity increases
Solution Approach 1:
The patent extracts and eliminates the frequency conversion and processing stage from the signal chain. By measuring capacitance changes directly, the system obtains flow information without requiring frequency modulation, demodulation, or conversion circuits, thereby simplifying signal processing while preserving all necessary flow information.
Solution Approach 2:
The patent substitutes the complex frequency-based signal processing chain with direct capacitance measurement and analysis. The capacitive changes caused by liquid flow are measured and processed directly in the capacitance domain, eliminating the need for frequency conversion, modulation, and demodulation stages.
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 system provides efficient flow detection with reduced complexity and cost, enabling convenient flow detection and characterization, container identification, and remote actuator control, while supporting disposable ducts and various beverages.
Implementation Method 1
a capacitive element comprising two electrodes provided at opposite sides of the duct along at least part of the length of the duct
Data Source
AI summary
A dispensing system for a beverage comprises in a tap system a bore for housing a duct. Along the bore, close to or on the duct, at least two electrodes are provided such that at least at some locations along the duct, the two electrodes are provided opposite to one another with the duct in between, thus constituting a capacitor. An oscillating signal is provided to one electrode and a signal is read out from the other electrode. As a beverage is drawn through the duct in a container, capacitance of the capacitor changes. The flowing beverage may have different characteristics, but capacitance may also change as the beverage in the duct is in conducting contact with a container that may be in contact with an earth contact. The change of capacitance results in a change of the amplitude of a detection circuit connected to the second electrode.