Rotational velocity transducer with pulses at proportional frequency - is particularly suited to liq. flow rate measurement devices using immersed impeller

摘要

An angular velocity transducer produces a pulse train of frequency proportional to that angular velocity, which is suitable for use in a liquid flow rate transducer. An impeller wheel (2) is immersed in the liquid in a suitable tubular chassis (1) and rotates at a rate proportional to the flow rate of the liquid. Two small permanent magnets (3) are mounted in the impeller, one being mounted to produce a field opposed to the other. Outside the chassis (1) which is of non magnetic material, is mounted a reed relay (5) and an auxiliary magnet (6) producing a field at right angles to the fields produced by the impeller magnets. The effect is to switch the relay to and from at a rate proportional to the impeller angular velocity, even when that velocity is low. The relay is in turn mounted in a magnetically conductive case (7).