Wave tooth gears using identical non-circular conjugating pitch curves
AssigneeTuthill Corporation
InventorCraig Cavanaugh
Life of this patent
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Abstract
This invention is directed to a novel wave tooth gear having a non-circular pitch curve and uniform wave teeth to create a tighter seal between meshing gears. The non-circular wave tooth gear has a major axis and a minor axis disposed perpendicular to the major axis, wherein the major axis is longer than the minor axis and includes a central hub, a plurality of teeth radially extending from the hub at locations surrounding the hub and a plurality of roots, each root positioned between adjacent teeth at locations surrounding the gear. The teeth include a head portion shaped as an arc segment of a first radius and the roots include a recess shaped as an arc segment of a second radius. The teeth heads are joined to adjacent roots by lines of tangency.
Claims27
A non-circular gear comprising:
- a hub having a major axis and a minor axis disposed perpendicular to said major axis, said major axis being longer than said minor axis;
- a plurality of teeth radially extending from said gear at locations surrounding said hub;
- a plurality of roots, each root positioned between adjacent teeth at locations surrounding said hub;
- each of said teeth including a head portion shaped as an arc segment of a first radius and each of said roots including a recess shaped as an arc segment of a second radius;
- and
- whereby said teeth heads are joined to adjacent roots by lines of tangency.
A flow meter comprising:
- a housing;
- an input port and an output port defined in said housing communicating with an enclosed chamber;
- a first non-circular gear journaled for a rotation within said chamber;
- a second non-circular gear journaled for rotation within said chamber, said non-circular gears having a plurality of wave teeth and a plurality of roots formed on a perimeter of said gears;
- said wave teeth on said gears having a perimeter defined by a tooth arc segment, and said roots having a perimeter defined by a root arc segment;
- and
- said teeth heads being adjoined to adjacent roots by lines of tangency, said first and second gear meshing to provide a seal to inhibit the back flow of fluid in the meter.
A fluid transfer device comprising:
- a housing;
- a first non-circular gear positioned within said housing and having perpendicularly disposed major and minor axes and including a plurality of gear teeth having teeth heads and roots disposed about a first non-circular pitch curve, said gear roots defined by a perimeter edge shaped as an arc segment having a first radius and said gear teeth defined by a perimeter edge shaped as an arc segment having a second radius;
- a second non-circular gear positioned within said housing and having perpendicularly disposed major and minor axes and including a plurality of gear teeth having teeth heads and roots disposed about a second non-circular pitch curve, said gear roots defined by a perimeter edge shaped as an arc segment having a first radius and said gear teeth defined by a perimeter edge shaped as an arc segment having a second radius;
- and
- said gears oriented so that said gear teeth of said first non-circular gear engage said gear teeth of said second non-circular gear.
A method of making a non-circular gear comprising the steps of:
- selecting the length of the major and minor axes;
- selecting a number of gear teeth;
- determining the radius of curvature points for a plurality of angles ranging from 0° to 360° using the following equation:
- r = 2 ab ( a + b ) - ( a - b ) cos 2 Θ
- converting the radius of curvature points into X and Y coordinates using the following equations:
- X=(cos Θ)(r)
- Y=(sin Θ)(r)
- plotting said X and Y coordinates and interconnecting said X and Y coordinates with line segments to form a pitch curve;
- adding the length of said line segments together to determine said pitch curve length;
- multiplying said number of teeth by a factor of 2 to determine a total number of centerpoints;
- determining an arc length by dividing said pitch curve length by said total number of centerpoints;
- drawing teeth and roots along said pitch curve, said teeth and root having diameters substantially equal to said arc length;
- interconnecting said teeth and roots by lines of tangency.
Dependencies are inferred from the claim text.