This invention relates to a flowmeter by which the flow of a fluid medium in, for example, a pipeline may be represented by an electrical signal, the electrical signal bearing a relationship to the rate of flow of fluid. The invention is particularly concerned with fuel flowmeters for engines.
By fluid is meant generally a liquid but the term can include also a vapour or gas.
In known constructions of flowmeters where the fluid flow rate varies over a wide range problems are encountered in providing for reliable consistent indication at low rates of flow. Temperature changes further affect the viscosity of the fluid and dimensions of the flow channel leading to variations. Flowmeters used in motor vehicle or water craft must further operate reliably and accurately over a long period and must be resistant to corrosion and chemical attack not only from the fuel but also from any additives therein. Known constructions of flowmeter have not fully met these requirements and have proved to be unreliable when used for fuel consumption measurement in motor vehicles.
An object of this invention is to provide a flowmeter which will have improved response to low fluid flow rates and which will provide an electrical output signal having a frequency proportional to flow. A further object is to provide improved temperature characteristics and resistance to corrosive effects over a long period of use.