Electronic water vol. meter for coffee machine - has paddle wheel rotated by water flow emitting angular position pulse trains for summing circuit coacting with comparator

摘要

A primary component (MV) rotated by the water flow, converts a series of angular offsets into an electronic pulse train (TR). The pulses are added in a summing circuit. An electronic comparator circuit, with a programmable and adjustable threshold, transmits an analog signal when a preset threshold has been attained in the summing circuit. The analog signal actuates an electric three-way valve (EL) in such manner that it moves from a first position supplying the coffee brewing water, into a second position interrupting the flow and connecting the machine to ambient air. Pref. an opto-electronic paddle wheel forms the primary component. Alternately, it is in the form of a proximity switch. A resetting feedback may be used for automatic zeroing of the summing circuit after a finished coffee machine cycle.