EP0106694A1 — Flexible power transmission belt and power transm…

Claim 1

Independent Claim 385 words

A flexible power transmission belt having a plurality of teeth (13) said belt teeth being separated by belt cavity portions (32), each belt tooth in longitudinal cross-section being symmetrical about a belt tooth center line (X-X), said belt tooth including a root portion (30, 31), a tip portion (25 to 27) and opposite convex arcuate flank portions (21, 22) extending from said tip portion, each said belt cavity portion (32) being symmetrical about a belt cavity center line, said belt tooth root portion being defined at least partly by first and second arcs (30, 31) approximating the arc of a circle on opposite sides of said belt tooth center line extending into the corresponding flank portions (21, 22) of the belt tooth and said belt cavity having a base portion (32).connecting said first arc of each tooth with said second arc of the next consecutive tooth, said base portion which in longitudinal cross-section is a line coinciding with a belt land line ( L ) which is colinear with base portions of other belt cavities on said belt, said belt tooth having a height dimension (H) measured between the extremity of said tooth tip portion and said belt land line (L) and having a width dimension (W) measured between said opposite flank portions along a line parallel to such belt land line and including the points (A, C) at which said first and second arcs intersect said flank portions, said belt tooth having a height to width relation within a first predetermined range, each said opposite flank portion being formed of a curve (21, 22) which approximates the arc of a circle whose center of curvature (23, 24) lies substantially on said belt land line on the side of the belt tooth center line which is opposite that of the flank portion in question and which curve is such that a tangent line (T) drawn to it at the point thereon (J, K) which is at a distance from the belt land line (L) equal to 0.3 times the width dimension (W) of the belt tooth forms an angle (α) with respect to the tooth center line which is within a second predetermined range, wherein said first predetermined range is from 0.50 to 0.67 and said second predetermined range is from 18 degrees to.23 degrees.

Claim 2

Dependent Claim 385 words

A flexible power transmission belt having a plurality of teeth (13) said belt teeth being separated by belt cavity portions (32), each belt tooth in longitudinal cross-section being symmetrical about a belt tooth center line (X-X), said belt tooth including a root portion (30, 31), a tip portion (25 to 27) and opposite convex arcuate flank portions (21, 22) extending from said tip portion, each said belt cavity portion (32) being symmetrical about a belt cavity center line, said belt tooth root portion being defined at least partly by first and second arcs (30, 31) approximating the arc of a circle on opposite sides of said belt tooth center line extending into the corresponding flank portions (21, 22) of the belt tooth and said belt cavity having a base portion (32).connecting said first arc of each tooth with said second arc of the next consecutive tooth, said base portion which in longitudinal cross-section is a line coinciding with a belt land line ( L ) which is colinear with base portions of other belt cavities on said belt, said belt tooth having a height dimension (H) measured between the extremity of said tooth tip portion and said belt land line (L) and having a width dimension (W) measured between said opposite flank portions along a line parallel to such belt land line and including the points (A, C) at which said first and second arcs intersect said flank portions, said belt tooth having a height to width relation within a first predetermined range, each said opposite flank portion being formed of a curve (21, 22) which approximates the arc of a circle whose center of curvature (23, 24) lies substantially on said belt land line on the side of the belt tooth center line which is opposite that of the flank portion in question and which curve is such that a tangent line (T) drawn to it at the point thereon (J, K) which is at a distance from the belt land line (L) equal to 0.3 times the width dimension (W) of the belt tooth forms an angle (α) with respect to the tooth center line which is within a second predetermined range, wherein said first predetermined range is from 0.50 to 0.67 and said second predetermined range is from 18 degrees to.23 degrees.

Claim 3

Dependent Claim 40 words

A flexible power transmission belt according to claim 1 wherein the longitudinal length of said belt cavity base portion (1) measured along said belt land line is in the range of 0.2 to 0.66 of said tooth width dimension (W).

Claim 4

Dependent Claim 260 words

A flexible power transmission belt having a plurality of teeth (13) separated from each other by a plurality of belt land areas (32) alternating with the teeth, each tooth having a center line (X-X) and comprising a pair of opposed flanks (21, 22) each of which in longitudinal cross-section has a generally convex arcuate contour, each flank being joined to the adjacent belt land area by a root (30, 31) having an arcuate contour approximating an arc of a circle having a given first radius, and having a tooth tip portion (25 to 27) connecting said pair of flanks at a location spaced from said root, each tooth having a longitudinal width dimension (W) measured between. the points (A, C) where said root arcs.intersect theopposing flanks of the belt tooth and a height dimension (H) measured from the belt land line (L, i.e. the line which in longitudinal cross-section passes through the tooth and ..is an extension of the belt land areas at each side of the tooth) to the outermost surface portion of the tooth tip, said height dimension being in the range of from 0.50 to 0.67 of said tooth width dimension, each of the arcuate flanks (21, 22) approximating an arc of a circle and being formed such that a line (T) drawn tangent thereto at a point (J, K ) spaced from the belt land line by a distance equal to 0.3 times the said width dimension will intersect the tooth center line (X-X) at an angle (α) in the range of from 18° to 23°.

Claim 5

Dependent Claim 260 words

A flexible power transmission belt having a plurality of teeth (13) separated from each other by a plurality of belt land areas (32) alternating with the teeth, each tooth having a center line (X-X) and comprising a pair of opposed flanks (21, 22) each of which in longitudinal cross-section has a generally convex arcuate contour, each flank being joined to the adjacent belt land area by a root (30, 31) having an arcuate contour approximating an arc of a circle having a given first radius, and having a tooth tip portion (25 to 27) connecting said pair of flanks at a location spaced from said root, each tooth having a longitudinal width dimension (W) measured between. the points (A, C) where said root arcs.intersect theopposing flanks of the belt tooth and a height dimension (H) measured from the belt land line (L, i.e. the line which in longitudinal cross-section passes through the tooth and ..is an extension of the belt land areas at each side of the tooth) to the outermost surface portion of the tooth tip, said height dimension being in the range of from 0.50 to 0.67 of said tooth width dimension, each of the arcuate flanks (21, 22) approximating an arc of a circle and being formed such that a line (T) drawn tangent thereto at a point (J, K ) spaced from the belt land line by a distance equal to 0.3 times the said width dimension will intersect the tooth center line (X-X) at an angle (α) in the range of from 18° to 23°.

Claim 6

Dependent Claim 43 words

A flexible power transmission belt according to claim 3 in which the belt land area (32) joining the roots of adjacent teeth, has a length dimension (1) in longitudinal cross-section in the range of from.0.2 to 0.66 of said tooth width dimension (W).

Claim 7

Dependent Claim 22 words

A flexible power transmission belt according to claim 3 or claim 4 in which said angle (α) is between 20° and 22°.

Claim 8

Dependent Claim 19 words

A flexible power transmission belt according to claim 3 or claim 4 in which said angle (α) is 21.5°.

Claim 9

Dependent Claim 40 words

A flexible power transmission belt according to any one of claims 3 to 6 in which said tooth tip portion exhibits.in longitudinal cross-section a contour comprised of a pair of non-intersecting arcs (25, 26) joined by a straight line (27).

Claim 10

Dependent Claim 39 words

A flexible power transmission belt according to any one of claims 3 .to 6 in which said tooth tip exhibits.in longitudinal cross-section a contour comprised of a pair of non-intersecting arcs (25', 26') joined by a convex curve (37').

Claim 11

Dependent Claim 44 words

A flexible power transmission belt according to any one of claims 3 to 6 in which the tooth tip exhibits in longitudinal cross-section a contour comprised of a convex curvilinear portion (37') which is a continuation of said generally convex arcuate flanks (21', 22').

Claim 12

Dependent Claim 61 words

A flexible power transmission belt according to any one of claims 3 to 9 in which the generally convex arcuate flanks (21, 22) are each, in longitudinal cross-section, a curve described by the equation y = /ax n / where (a) is a constant between 104, and 65,800 and (n) has a value in the range of from 3 to 7.5.

Claim 13

Dependent Claim 62 words

A flexible power tranmission belt according to any one of claims 3 to 9 in which the generally convex arcuate flanks (21, 22) are formed by arcs of a circle centered on the belt land line, the radii (R 1 , R 2 ) of said arcs being in the range of between 0.7 and 0.9 of the belt tooth width (W).

Claim 14

Dependent Claim 56 words

A flexible power transmission belt according to any one of claims 3 to 9 in which the generally convex arcuate flanks (21, 22) are formed by arcs of a circle centered on the belt land line, the radii (R 1 , R 2 ) of said arcs being equal to 0.85 times the belt tooth width

Claim 15

Dependent Claim 31 words

A flexible power transmission belt according to any one of claims 3 to 9 in which the generally convex arcuate flanks (21, 22)-are each approximated by an involute of a circle.

Claim 16

Dependent Claim 51 words

A flexible power transmission belt according to any one of claims 3 to 13 in which the length of each of the arcuate flanks (21, 22) of the belt tooth measured along the outline of such flank in longitudinal cross-section is at least equal to 40% of the height dimension (H).

Claim 17

Dependent Claim 90 words

A flexible power transmission belt according to claim 7 wherein said height dimension (H) is equal to 0.60 times the width dimension (W), said angle (α) is 21.5°, said length dimension (1) of said belt land area is 0.2 times the tooth width dimension (W), and each said convex flank (21, 22) is an arc of a circle whose center (23, 24) lies on said belt land line (L) and whose radius (R 1 , R 2 ) is equal to 0.85 times the tooth width dimension ( W ).

Claim 18

Dependent Claim 53 words

A flexible power transmission belt according to claim 15 in which said pair of non-intersecting arcs (25,26) at the tooth tip have radii equal to 0.19 times the width dimension (W), and said straight line (27) joining said tooth tip arcs has a length equal to 0.36 times the tooth width dimension (W).

Claim 19

Dependent Claim 151 words

A flexible power transmission belt according to claim 8 in which said height dimension (H') is equal to 0.63 times the width dimension (W), said angle ( α') is 21.5°, said length dimension (1) of said belt land area is 0.49 times the tooth width dimension (W'), said pair of non-intersecting arcs (25', 26') at the tooth tip have radii equal to 0.19 times the tooth width dimension (W"), said convex curve (37') joining said tooth tip arcs being an arc of a circle having its center on the belt land line and having a radius of a length equal to 0.63 times the tooth width dimension (W') and each said convex flank (21', 22') being an arc of a circle whose center (23', 24') lies on said line (L') which is an extension of said belt land areas and whose radius isequal to 0.85 times the tooth width dimension (W').

Claim 20

Dependent Claim 54 words

A power transmission system comprising the combination of (A) an endless flexible power transmission belt according to any one of the preceding claims and (B) a pulley having a plurality of identical peripheral belt-engaging teeth defining between them pulley cavities (13p) wherein each pulley cavity is substantially the conjugate of one said belt tooth.

Claim 21

Dependent Claim 366 words

A power transmission system comprising the combination of (A) an endless flexible power transmission belt according to any one of the preceding claims and (B) a pulley having a plurality of identical peripheral belt-engaging teeth defining between them pulley cavities (13p), wherein each pulley cavity possesses substantially identical fore and aft flank surfaces (21 p , 22 p ), at least part of said flank surfaces being shaped in cross-section as a curve approximating the arc of a circle and said pulley teeth having pulley land surfaces (32 ) at the tips thereof, said land surfaces defining in longitudinal cross-section portion of a pulley land line (Lp) approximating a circle concentric with the center of the pulley, and said pulley cavity having a cavity bottom portion (26 p , 27 ,28 ) connecting the opposite arcuate flanks thereof at points on said flanks furthest spaced from said pulley land line, each said pulley tooth tip having arcuate portions (30 p , 31 p ) adjacent the pulley land line (Lp) and joining the respective arcuate flank portions (21 p , 22 ) to the adjacent pulley land areas (32 p ) and said cavity having a width dimension (W ) measured between corresponding points (A , C ) of said arcuate flank portions where said arcuate portions of said pulley tooth tip connect with respective arcuate flank surfaces, said cavity having a depth (Hp) measured between said pulley land line (L p ) and the portion of the cavity bottom portion which is spaced furthest from said pulley land line, the curvature of said cavity flank surfaces (21 p , 22 p ) being such that they are substantially concave with respect to the bodyof the pulley and that a line (T p ) drawn tangent thereto at a point (J p , K ) thereon spaced from said pulley land line (Lp) a distance 0.3 times said width dimension (W ) makes an angle ( α p ) with the center line (X - X) of said pulley cavity, said pulley cavity having a depth-to-width relation in the range of from 0.47 to 0.64, and said angle (α p ) being from 18.5° to 23.5°.

Claim 22

Dependent Claim 31 words

A power transmission system according to claim 19 in which said belt tooth width (W) is within therange of from 0.95 to 1.00 of the pulley cavity width (W p ).

Claim 23

Dependent Claim 32 words

A power transmission system according to claim 18 in which said belt tooth width (W) is within the range of from 0.97 to 0.99 of the pulley cavity width (W p ).

Claim 24

Dependent Claim 23 words

A power transmission system according to claim 18 in which the belt tooth (W) is approximately 0.98 of the pulley cavity width (Wp).

Claim 25

Dependent Claim 57 words

A power transmission system according to any one of claims 19 to 22 in which said pulley tooth tips have a substantially flat tip land area (32 p ) the length (1 p ) of which in longitudinal cross-section is within the range of from 0.1 to 0.65 of the width W p of the pulley cavity.

Claim 26

Dependent Claim 27 words

A power transmission system according to any one of claims.19 to 23 in which the belt tooth height (H) is equal to the pulley cavity depth (Hp).

Claim 27

Dependent Claim 26 words

A power transmission system according to any one of claims 19 to 23 in which the belt tooth height (H) exceeds the pulley cavity depth (Hp).

Claim 28

Dependent Claim 26 words

A power transmission system according to any one of claims 19 to 23 in which the pulley cavity depth (Hp) exceeds the belt tooth height (H).

Claim 29

Dependent Claim 73 words

A power transmission system according to any one of claims 19 to 25 in which the angle α p is 22°, the depth Hp of the pulley cavity is equal to 0.59 of the pulley cavity width W p , and the pulley cavity flank portions are arcs of circles having a radius equal to 0.81 times the pulley cavity width W p and centered on the pulley land line L p .

Claim 30

Dependent Claim 85 words

A power transmission system according to claim 19 wherein said transmission belt is as claimed in claim 16 and said bottom portion of said pulley cavity comprises a pair of non-intersecting arcs (R3p, R4 p ) of radii equal to 0.18 times the pulley cavity width (W ) and the bottom surface (27 p ) of the pulley cavity is defined by a straight line of length equal to 0.38 times the pulley cavity width ( W ) and connecting said pair of non-intersecting arcs.

Claim 31

Dependent Claim 68 words

A power transmission system according to any one of claims 18 to 28 in which each of said curved flank portions of said belt teeth and of said pulley cavities approximates an arc of a circle centered on the corresponding land line of the belt and pulley respectively, on the side of the center line opposite to the one at which the respective curved flank portion is located.

Claim 32

Dependent Claim 123 words

A power transmission system according to claim 22 in which the belt is as claimed in claim 16, and for the pulley the angle α p is 22°, the pulley cavity depth (Hp) is 0.59 of the pulley cavity width (W p ), each said substantially concave arcuate flank surface (21 , 22 ) is formed by an arc of a circle centered on said pulley land line (L p ) and having a radius equal to 0.81 W , said pulley cavity bottom portion comprising a pair of non-intersecting arcs of radii equal to 0.18 W p and a straight line bottom portion (27 p ) connecting said pair of non-intersecting arcs and being of a length equal to 0.38 W .

Claim 33

Dependent Claim 120 words

A power transmission system according to claim 22 in which the belt is as claimed in claim 17, and for the pulley the angle α p is 22°, the pulley cavity depth (Hp) is 0.61 of the pulley cavity width (W p ), each said substantially concave arcuate flank surface (21 p , 22 p ) is formed by an arc of a circle centered on said pulley land line (L ) and having a radius equal to 0.81 W , said pulley cavity bottom portion comprising a pair of non-intersecting arcs of radii equal to 0.36 Wand a curved line connecting said.pair of non-intersecting arcs and being formed with a radius of a length equal to 0.60 W .

Flexible power transmission belt and power transmission system

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