Summary: To make eddy street flowmeter applies to the metric requirement of tap water industry, this literary grace detects with electromagnetism method, use such as MSP430 odd the chip of small power comsumption such as a machine, combine software technology, the design gives a kind to have power comsumption low, span wide, precision is advanced the water meter of electromagnetism eddy street of the characteristic.

Keyword: Low power comsumption, eddy street, water meter

One Foreword

The water meter of electromagnetism eddy street that article place designs is based on the principle of eddy street flowmeter, and use sensor of electromagnetism eddy street collect discharge signal. Eddy street flowmeter has span wide, without movable component, move reliable, safeguard simple, pressure loss is small, have the advantage such as taller metric precision. And use electromagnetism to detect method, make outside the advantage that water meter has besides flowmeter of general eddy street, still can remove the oscillatory interference on three-dimensional direction, have fight electromagnetism very well to disturb ability.

Whole system uses power supply of 3.6V lithium battery, thereby water meter can work in out-of-the-way environment. Change often to avoid batteries, reducing water meter power comsumption is the first goal that the system designs, the from hardware, software 2 respects consider to reduce power comsumption method when the design.

Eddy market signal is low intensity, low frequency in the expression below the circumstance of low velocity of flow, so the measurement of the signal below low velocity of flow is the difficulty that enlarges span limits. Through choosing property advantageous operation amplifier is mixed improve of parameter ceaselessly to enlarge circuit, water meter realized the signal below low velocity of flow to measure.

2 The working principle of water meter of electromagnetism eddy street

Eddy street flowmeter is according to Carmen eddy street principle undertakes discharge is measured. A blame is inserted in going from place to place liquid clipper-built columnar content (like trigonometry cylinder or echelon cylinder) namely eddy happening body, the fluid counts range in certain Reynolds immanent eddy produces body to be able to produce two asymmetry downstream and the eddy that has the law again. Eddy shows following concern between detached frequency and fluid velocity of flow:
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