Capacitive Flow Detection Circuit Without Bulky Inductors
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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 a simplified, cost-effective method for detecting flow through ducts.
Innovation Solution
A capacitive flow detection circuit using alternating signal sources, capacitive elements with electrodes on opposite sides of the duct, and a detection circuit that processes signal amplitude values to determine flow, implemented in analogue or digital domains, with peak detection and feedback control loops for precise flow detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inductance is used for capacitive flow measurement, then measurement precision is improved, but device complexity and cost increase due to bulky components and additional circuitry
Solution Approach 1:
The patent extracts and eliminates the inductance component from the measurement system. Instead of using a traditional capacitive measurement circuit with inductance for frequency-to-voltage conversion, the invention uses a simplified capacitive sensor system where the capacitive element directly interfaces with a detection circuit that measures capacitance changes without requiring inductive components or complex frequency conversion circuitry.
Solution Approach 2:
The patent replaces the mechanical/electromagnetic resonance-based capacitive measurement system (which requires inductance and oscillating circuits) with an electrical field-based direct capacitance measurement system. The detection circuit directly senses capacitance changes caused by beverage flow through the duct, substituting complex electromagnetic resonance mechanisms with a simpler electrical field sensing approach.
2Measurement precision
If inductance and frequency-to-voltage conversion circuitry are used, then flow detection capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent employs inexpensive capacitive sensor elements and simple detection circuits that can be manufactured at low cost. The capacitive sensor uses basic electrode structures and the detection circuit uses straightforward capacitance measurement techniques, eliminating the need for expensive inductors, frequency synthesizers, and complex signal processing hardware, thereby significantly reducing manufacturing costs.
Solution Approach 2:
The invention extracts and removes costly frequency-to-voltage conversion circuitry and inductive components from the system. By directly measuring capacitance changes in the sensor element, the system eliminates the need for expensive oscillating circuits, frequency counters, and conversion amplifiers, resulting in a cost-effective flow detection solution.
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 reduces complexity and cost while providing accurate detection of beverage flow, allowing for real-time monitoring of flow characteristics and container type, enabling efficient resource management and user feedback.
Implementation Method 1
a capacitive element (204) comprising two electrodes (132, 134) provided at opposite sides of the duct (120)
Data Source
Figure 1~2A
Figure 2B
Figure 3
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.