Patent ID: 8312785

Claim:
An oval gear set for use in a flow meter, the gear set comprising first and second gears identical to each other and configured to engage at a fixed center-to-center distance such that the first and second gears mesh at all angular positions, each gear of the oval gear set comprising: a hub comprising: an oval body having a major axis and a minor axis extending through a center of the hub; and a root profile wall circumscribing the major and minor axes; and a plurality of gear teeth extending from the root profile wall, each gear tooth having a pair of contact surfaces with circular involute curve profiles; wherein the circular involute curve profiles for each tooth on the first gear is generated from a base circle having a radius Rb 1 derived from a modified elliptical pitch curve having a pitch radius R 1 at an angular position Θ from the center; and wherein the modified elliptical pitch curve is defined by the following polar coordinate equation: R ⁢ ⁢ 1 ⁢ ( Θ ) = S ⁡ [ 1 - ( E ) 2 ] 1 - ( E ) ⁢ cos ⁡ ( 2 ⁢ ⁢ Θ ) wherein S and E are constants representing the scale and the eccentricity, respectively, of the pitch curve.