Mass-flow sensing transducer

Claim 1

A variable capacitance device responsive to the impingement of a stream of gas on its flexible sensing element, used for measuring the mass-flow of air expressed in pounds per unit time, comprising: (a) a rigid capacitor plate having a narrow, cylindrical surface provided with a dielectric material of a well defined thickness, and being provided with means for connecting a terminal lead to its electrically conductive base material; (b) a flexible capacitor plate having straight, elongated inner and outer surfaces, and being provided with means for connecting a terminal lead to its electrically conductive base material; (c) a structure for supporting said rigid, and said flexible capacitor plates, having mounting means for being fixed to an air conveying duct; wherein, said flexible capacitor plate being fixedly arranged to extend longitudinally along said rigid capacitor plate, so that said inner surface of said flexible capacitor plate barely touches one end of said curved surface of said dielectric material, where said rigid and said flexible capacitor plates are generally disposed parallel to one another, and wherein said surface of said dielectric material is curving substantially away from said inner surface of said flexible capacitor plate; and wherein, in operation, the the impingement of said stream of air on said outer surface of said flexible capacitor plate causes the gradual bending of said flexible capacitor plate over said curved surface of said dielectric material, thereby, in turn, causing an increase in the abutting area between said rigid and said flexible capacitor plate, which is accompanied by a corresponding change in capacitance.