Pulley for positive drive systems

Claim 2

A power transmission system consisting of at least one small diameter toothed pulley in combination with a flexible toothed belt having belt teeth of cross-sectional contour substantially composed of two substantially circular arcs defining substantially curved belt tooth tips, the pulley teeth being composed of tip portions connected by cavity portions, each tip portion having a longitudinal cross-sectional contour partially composed of two substantially circular arcs, said arcs having centers of curvature displaced from each other, the center of curvature of each arc being located on the same side of the center line of said tip portion as its respective arc, the outermost portion of each tooth tip joining the two arcs forming a line segment, the length of the line segment being from 6% to 33% of the width of the belt teeth, and the distance between the outermost portion of the pulley teeth cavities and the innermost portion of the pulley teeth cavities being less than the depth of the belt teeth which are not in contact with the pulley.

Claim 3

The power transmission system of claim 1, wherein said pulley teeth line segments are circular arcs.

Claim 4

The power transmission system of claim 1, wherein said pulley teeth arcs are tangent to their respective line segments at their points of intersection.

Claim 5

The power transmission system of claim 1, wherein said pulley teeth line segments are straight lines.

Claim 6

The power transmission system of claim 1, wherein the longitudinal cross-sectional contours of the pulley teeth cavities are composed of substantially circular arcs.

Claim 7

The power transmission system of claim 1, wherein the belt teeth in contact with the pulley are in compressive engagement with some of the pulley teeth cavities.

Claim 8

The power transmission system of claim 6, wherein the pulley teeth cavities are non-conjugate with the belt teeth.

Claim 9

The power transmission system of claim 6, wherein the pulley teeth line segments are circular arcs.

Claim 10

The power transmission system of claim 6, wherein said arcs partially forming the contours of the pulley teeth are tangent to the line segments at their points of intersection.

Claim 11

The power transmission system of claim 6, wherein the pulley teeth line segments are straight lines.

Claim 12

The power transmission system of claim 6, wherein the longitudinal cross-sectional contours of the pulley teeth cavities are composed of substantially circular arcs.

Claim 13

A power transmission system comprising at least one pulley with teeth in combination with a flexible belt with teeth, the pulley teeth being a non-conjugate form of the belt teeth, the pulley teeth being separated by pulley cavity portions and the belt teeth being separated by belt cavity portions, each pulley tooth in longitudinal cross-section being symmetrical about a pulley tooth centerline intersecting with a center of said pulley, said pulley tooth including a pulley tip portion and opposite pulley flank portions extending from said pulley tip portion, the pulley tip portion being defined by first and second circular arcs on opposite sides of said pulley tooth centerline, the centers of curvature of said first and second arcs being displaced from each other on a circular arc having a common center with said pulley, a peripheral pulley segment at the outermost portion of said pulley tooth tip joining the first and second arcs, each said pulley cavity being symmetrical about a pulley cavity centerline intersecting with the center of said pulley, said pulley cavity being partially defined by a third circular arc having a center of curvature on the pulley cavity centerline, said third circular arc defining a base portion of said pulley cavity and extending from said pulley cavity base portion into the flank portions of adjacent pulley teeth, portions of said first and second arcs extending from the tip portion of said pulley tooth toward the respective flank portions of said pulley tooth, each belt tooth in longitudinal cross-section being symmetrical about a belt tooth centerline, said belt tooth including a substantially curved belt tip portion partially defined by fourth and fifth circular arcs extending into opposite flank portions of said belt tooth, said belt cavity being symmetrical about a belt cavity centerline and being partially defined by the fourth arc of one belt tooth and the fifth arc of an adjacent belt tooth, said belt cavity having a base portion exceeding the width of said pulley tooth tip, and the center of curvature locations and the radii of said third, fourth and fifth circular arcs being selected such that in a no-load condition of the belt and the pulley, the height of said belt tooth along said belt tooth centerline measuring from the belt tooth tip to the intersection of said belt tooth centerline with a line tangent to consecutive belt tooth cavities exceeds the depth of said pulley cavity along said pulley cavity centerline measuring from the intersection of said third arc with said pulley cavity centerline to the intersection of said pulley cavity centerline with an arc having a common center with said pulley and tangent to consecutive pulley teeth tips.

Claim 14

A power transmission system comprising at least one pulley with teeth in combination with a flexible belt with teeth, the pulley teeth being a non-conjugate form of the belt teeth, the pulley teeth being separated by pulley cavity portions and the belt teeth being separated by belt cavity portions, each pulley tooth in longitudinal cross-section being symmetrical about a pulley tooth centerline intersecting with a center of said pulley, said pulley tooth including a pulley tip portion and opposite pulley flank portions extending from said pulley tip portion, the pulley tip portion being defined by first and second circular arcs on opposite sides of said pulley tooth centerline, the centers of curvature of said first and second arcs being displaced from each other on a circular arc having a common center with said pulley, a peripheral pulley segment at the outermost portion of said pulley tooth tip joining the first and second arcs, each said pulley cavity being symmetrical about a pulley cavity centerline intersecting with the center of said pulley, said pulley cavity being partially defined by a third circular arc having a center of curvature on the pulley cavity centerline, said third circular arc defining a base portion of said pulley cavity and extending from said pulley cavity base portion into the flank portions of adjacent pulley teeth, portions of said first and second arcs extending from the tip portion of said pulley tooth toward the respective flank portions of said pulley tooth, each belt tooth in longitudinal cross-section being symmetrical about a belt tooth centerline, said belt tooth including a substantially curved belt tip portion partially defined by fourth and fifth circular arcs extending into opposite flank portions of said belt tooth, said belt cavity being symmetrical about a belt cavity centerline and being partially defined by the fourth arc of one belt tooth and the fifth arc of an adjacent belt tooth, said belt cavity having a base portion exceeding the width of said pulley tooth tip, and the center of curvature locations and the radii of said third, fourth and fifth circular arcs being selected such that in a no-load condition of the belt and the pulley, the height of said belt tooth along said belt tooth centerline measuring from the belt tooth tip to the intersection of said belt tooth centerline with a line tangent to consecutive belt tooth cavities exceeds the depth of said pulley cavity along said pulley cavity centerline measuring from the intersection of said third arc with said pulley cavity centerline to the intersection of said pulley cavity centerline with an arc having a common center with said pulley and tangent to consecutive pulley teeth tips.

Claim 15

In a power transmission system including at least one pulley with teeth in combination with a flexible belt with teeth wherein the belt teeth are separated by belt cavity portions, and each belt tooth in longitudinal cross-section is symmetrical about a belt tooth centerline, with each belt tooth including a substantially curved belt tip portion partially defined by first and second circular arcs extending into opposite flank portions of said belt tooth, wherein the belt cavity is symmetrical about a belt cavity centerline and is partially defined by the first arc of one belt tooth and the second arc of an adjacent belt tooth, and wherein the belt cavity has a base portion, the pulley comprising pulley teeth that are a non-conjugate form of the belt teeth, the pulley teeth being separated by pulley cavity portions and each pulley tooth in longitudinal cross-section being symmetrical about a pulley tooth centerline intersecting with a center of said pulley, said pulley tooth including a pulley tip portion having a width less than the width of the belt cavity base portion, and opposite pulley flank portions extending from said pulley tip portion, the pulley tip portion being defined by third and fourth circular arcs on opposite sides of said pulley tooth centerline, the centers of curvature of said third and fourth arcs being displaced from each other on a circular arc having a common center with said pulley, a peripheral pulley segment at the outermost portion of said pulley tooth tip joining the third and fourth arcs, each said pulley cavity being symmetrical about a pulley cavity centerline intersecting with the center of said pulley, said pulley cavity being partially defined by a fifth circular arc having a center of curvature on the pulley cavity centerline, said fifth circular arc defining a base portion of said pulley cavity and extending from said pulley cavity base portion into the flank portions of adjacent pulley teeth, portions of said third and fourth arcs extending from the tip portion of said pulley tooth toward the respective flank portions of said pulley tooth, the center of curvature location and the radii of said fifth circular arc being selected such that in a no-load condition the depth of said pulley cavity along said pulley cavity centerline measuring from the intersection of said fifth arc with said pulley cavity centerline to the intersection of said pulley cavity centerline with an arc having a common center with said pulley and tangent to consecutive pulley teeth tips is less than the height of said belt tooth along said belt tooth centerline measuring from the belt tooth tip to the intersection of said belt tooth centerline with a line tangent to consecutive belt tooth cavities.

Claim 16

In a power transmission system including at least one pulley with teeth in combination with a flexible belt with teeth wherein the belt teeth are separated by belt cavity portions, and each belt tooth in longitudinal cross-section is symmetrical about a belt tooth centerline, with each belt tooth including a substantially curved belt tip portion partially defined by first and second circular arcs extending into opposite flank portions of said belt tooth, wherein the belt cavity is symmetrical about a belt cavity centerline and is partially defined by the first arc of one belt tooth and the second arc of an adjacent belt tooth, and wherein the belt cavity has a base portion, the pulley comprising pulley teeth that are a non-conjugate form of the belt teeth, the pulley teeth being separated by pulley cavity portions and each pulley tooth in longitudinal cross-section being symmetrical about a pulley tooth centerline intersecting with a center of said pulley, said pulley tooth including a pulley tip portion having a width less than the width of the belt cavity base portion, and opposite pulley flank portions extending from said pulley tip portion, the pulley tip portion being defined by third and fourth circular arcs on opposite sides of said pulley tooth centerline, the centers of curvature of said third and fourth arcs being displaced from each other on a circular arc having a common center with said pulley, a peripheral pulley segment at the outermost portion of said pulley tooth tip joining the third and fourth arcs, each said pulley cavity being symmetrical about a pulley cavity centerline intersecting with the center of said pulley, said pulley cavity being partially defined by a fifth circular arc having a center of curvature on the pulley cavity centerline, said fifth circular arc defining a base portion of said pulley cavity and extending from said pulley cavity base portion into the flank portions of adjacent pulley teeth, portions of said third and fourth arcs extending from the tip portion of said pulley tooth toward the respective flank portions of said pulley tooth, the center of curvature location and the radii of said fifth circular arc being selected such that in a no-load condition the depth of said pulley cavity along said pulley cavity centerline measuring from the intersection of said fifth arc with said pulley cavity centerline to the intersection of said pulley cavity centerline with an arc having a common center with said pulley and tangent to consecutive pulley teeth tips is less than the height of said belt tooth along said belt tooth centerline measuring from the belt tooth tip to the intersection of said belt tooth centerline with a line tangent to consecutive belt tooth cavities.