Capacitive Rotation Detection Eliminates Coils in Water Meters
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Solution Overview
Problem
Existing fluid flow rate measuring devices, such as electronic water meters, face high costs due to the use of expensive coils and are prone to malfunctioning when exposed to permanent magnets, requiring high-frequency reference clocks and large capacitance smoothing capacitors to manage spike currents.
Innovation Solution
A fluid flow rate measuring device utilizing a first circular plate with a fan-shaped common capacitor electrode and an insulator portion, along with a second circular plate featuring point-symmetrically arranged fan-shaped capacitor electrodes, detects capacitance changes to determine rotation speed and direction without coils, eliminating the need for expensive coils and high-frequency components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coils are used in the rotation detection unit, then the device can detect rotation speed and direction, but the cost increases and the device becomes prone to malfunctioning when exposed to permanent magnets
Solution Approach 1:
The patent replaces the electromagnetic detection system (coils) with a capacitive detection system. The rotation detection unit uses capacitor electrodes that detect changes in capacitance based on the position of the circular plate, eliminating the need for coils and making the device immune to permanent magnet interference.
Solution Approach 2:
The patent uses simple capacitor electrodes made of conductive materials instead of expensive coils. The capacitor structure is much simpler and cheaper to manufacture, using basic conductive plates and dielectric materials rather than wound wire coils.
2Device complexity
If coils are used in the rotation detection unit, then the device can detect rotation speed and direction, but the device requires high-frequency reference clocks and large capacitance smoothing capacitors to manage spike currents
Solution Approach 1:
The patent replaces the electromagnetic induction-based coil system with a direct capacitive sensing system. The capacitor electrodes directly measure the position of the circular plate through capacitance changes, eliminating the need for high-frequency excitation signals and the associated spike current management circuitry.
Solution Approach 2:
The patent extracts and removes the coil component and its associated high-frequency circuitry from the rotation detection unit. By using only capacitor electrodes, the design eliminates the need for high-frequency reference clocks and large smoothing capacitors, significantly simplifying the overall circuit.
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
This solution reduces costs by eliminating the need for coils and high-frequency components, prevents malfunctioning near permanent magnets, and simplifies the circuit by eliminating spike currents and the requirement for large capacitance smoothing capacitors.
Implementation Method 1
detecting a capacitance of each of first, second and third capacitors each formed between the common capacitor electrode and each of the first, second and third capacitor electrodes, respectively
Data Source
AI summary
There is offered a water meter that requires no coil so that its cost is reduced. The water meter is formed to include an impeller, a rotation reduction unit, a first circular plate, a second circular plate, a rotation detection unit and an arithmetic unit. The rotation detection unit forms first, second and third combination capacitors with a switching circuit. The rotation detection unit detects changes in capacitances of the first, second and third combination capacitors associated with a rotation of the first circular plate. The arithmetic unit is configured so as to electrically detect the rotation angle θ of the first circular plate based on the changes in the capacitances.