Patent ID: 8425212
Filing Date: 2013-04-23
Classification: G01F

Abstract:
1. A positive displacement flowmeter, comprising: a pair of helical gears in a casing thereof; wherein the flowmeter measures flow using rotations of the helical gears; wherein the pair of helical gears employ an oval pitch curve having two or less leaves as their reference rack tooth profile; wherein a moving radius of the oval pitch curve is expressed by ρ=a/(1−b cos nθ) (where “ρ” is the moving radius that is a distance from the center of rotation to the oval pitch curve, “a” is a similarity factor, “b” is a degree of flatness, “n” (n≦2) is number of leaves, and “θ” is an argument); wherein when the number of leaves n is n=2, the similarity factor “a”, the degree of flatness “b”, and a distance “g where a cutter pressure angle at a pitch point is “α