Debris shedding flanged sprocket

Abstract

Side flanged sprockets for toothed belt systems, such as mobility applications (such as bicycles, electric bicycles or E-bikes, powered wheelchairs, scooters, etc.), the sprockets having bi-directional debris-shedding elements that direct debris (e.g., dirt, dust, water, etc.) laterally out from the sprocket. The sprockets have at least one side flange, which is discontinuous along its length. For some sprockets having a flange on each side, the flanges alternate from one side to the other; these alternating-side flanges may be in a symmetrical arrangement or asymmetrical arrangement.

Description

DEBRIS SHEDDING FLANGED SPROCKETCROSS-REFERENCE

[0001] This application claims priority to U.S. Provisional application no. 63 / 578,321 filed August 23, 2023, the entire disclosure of which is incorporated herein by reference for all purposes.TECHNICAL FIELD

[0002] This disclosure relates to sprockets for use with a toothed belt system. More specifically, the disclosure relates to flanged sprockets.BACKGROUND

[0003] Toothed belts that engage sprockets for power transmission in mobility applications (such as electric bicycles or E-bikes, powered wheelchairs, scooters, etc.) usually require some type of belt- tracking to inhibit belt-sprocket misalignment, which can detrimentally affect system performance. Often, the belt-tracking mechanism includes side-flanges on the sprocket, the flanges oriented orthogonal to the teeth of the belt and to the rungs of the sprocket that engage the teeth. Such side flanges constrain the belt laterally. Another belt-tracking mechanism is a center flange on the sprocket and a lengthwise cut along the centerline of the belt. Such a center flange also constrains the belt laterally.

[0004] Sprockets can be manufactured using various known methods and technologies. In one example, sprockets are formed using injection molding and / or overmolding methods. In such methods, a mold is used to form the specific shape and dimensions of the sprocket, including the tooth profile for the sprocket and the flange(s). Injection molding processes can be economical and capable of forming very precise tooth-engaging profiles. However, sprockets having side flanges are often difficult to remove from the mold, especially sprockets with side flange features on both lateral sides of the sprocket. Such sprockets mandate careful tooling design consideration to achieve manufacturable geometries without inciting premature tooling wear and / or damage.

[0005] Other methods of forming flanged sprockets are available, such as permanent mold casting / overcasting, metal injection molding, powder metallurgy, and CNC machining. However,-1-SUBSTITUTE SHEET (RULE 26)these techniques can be expensive, time consuming, mandate secondary operations, and often require additional assembly to yield a finished part.SUMMARY

[0006] The present disclosure is directed to a sprocket having side flanges with a debris shedding element between adjacent belt-engaging teeth, the sprocket being able to be formed by die casting, injection molding, and other techniques.

[0007] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary, and the foregoing Background, is not intended to identify key aspects or essential aspects of the claimed subject matter. Moreover, this Summary is not intended for use as an aid in determining the scope of the claimed subject matter.

[0008] In some embodiments, a side flanged sprocket is described, the sprocket including a plurality of equally spaced parallel rungs each rung having a first end and a second end, the first ends of the rungs at a first side of the sprocket and the second ends of the rungs at a second side of the sprocket, a land between each pair of rungs, with a channel in the land extending from the first side to the second side, a first circumferential flange at the first side that is discontinuous, and a second circumferential flange at the second side. Each of the first flange and the second flange have a plurality of debris shedding holes therethrough, a debris shedding hole located between each pair of rungs and proximate the channel.

[0009] In other embodiments, a sprocket is described, the sprocket including a plurality of equally spaced parallel rungs extending from a first side of the sprocket to a second side of the sprocket, with a land present between the rungs, a first circumferential flange at the first side, a second circumferential flange at the second side, with a volume defined by two adjacent rungs, the land therebetween, the first side, and the second side. A first debris shedding element is at the first side and a second debris shedding element is at the second side, the debris shedding elements providing bidirectional lateral fluid communication from the volume to external to the sprocket. In some embodiments, there is no radially inward fluid communication or expulsion from the volume.

[0010] The second flange at the second side can be continuous or discontinuous and is integrally formed (e.g., molded, cast) with the rest of the sprocket. At least the second flange rises-2-SUBSTITUTE SHEET (RULE 26)above the rung tips, often to a height of at least 10 mm above the rung tips, with a geometry optimized to guide an engaging belt laterally inboard to mitigate derailment events.

[0011] The sprockets may be part of a belt drive system, which includes a belt (e.g., an endless belt) and the sprocket. Some belt drive systems have a first sprocket accompanying a crank and a second sprocket accompanying a driven shaft, where one or both the sprockets have the features described herein.

[0012] These and other aspects of the technology described herein will be apparent after consideration of the Detailed Description and Figures herein. It is to be understood, however, that the scope of the claimed subject matter shall be determined by the claims as issued and not by whether given subject matter addresses any or all issues noted in the Background or includes any features or aspects recited in the Summary.BRIEF DESCRIPTION OF THE FIGURES

[0013] FIG. 1 is a perspective view of a first embodiment of a sprocket.

[0014] FIG. 2 is a cross-sectional view of the sprocket of FIG. 1 taken along line 2-2 ofFIG. 1.

[0015] FIG. 3 A is a side view of the sprocket of FIG. 1; FIG. 3B is a schematic rendering of the flanges of FIG. 3 A.

[0016] FIG. 4 is a schematic rendering of the flanges of the sprocket of FIG. 1 illustrating a debris path.

[0017] FIG. 5 is an enlarged perspective view of a second embodiment of a sprocket.

[0018] FIG. 6A is a perspective view of a third embodiment of a sprocket; FIG. 6B is a schematic rendering of the sprocket of FIG. 6A.

[0019] FIG. 7A is a perspective view of a fourth embodiment of a sprocket; FIG. 7B is a partial cross-sectional view of the sprocket of FIG. 7A.

[0020] FIG. 8 is a perspective view of a fifth embodiment of a sprocket.

[0021] FIG. 9 is a perspective view of a sixth embodiment of a sprocket.-3-SUBSTITUTE SHEET (RULE 26)DETAILED DESCRIPTION

[0022] As indicated above, the present disclosure is directed to side flanged sprockets for toothed belt systems, such as mobility applications (such as bicycles, electric bicycles or E-bikes, powered wheelchairs, scooters, etc.), the sprockets having bi-directional debris-shedding elements that direct debris (e.g., dirt, dust, water, etc.) laterally out from the sprocket. The sprockets have at least one side flange, which is discontinuous along its length. For some sprockets having a flange on each side, the flanges alternate from one side to the other; these alternating-side flanges may be in a symmetrical arrangement or asymmetrical arrangement. Other sprockets may have a discontinuous flange on one side and a continuous flange on the other side.

[0023] In the following description, reference is made to the accompanying drawing that forms a part hereof and in which is shown by way of illustration at least one specific implementation. The following description provides additional specific implementations. It is to be understood that other implementations are contemplated and may be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense. While the present disclosure is not so limited, an appreciation of various aspects of the disclosure will be gained through a discussion of the examples, including the figures, provided below. In some instances, a reference numeral may have an associated sub-label consisting of a lower-case letter to denote one of multiple similar components. When reference is made to a reference numeral without specification of a sub-label, the reference is intended to refer to all such multiple similar components.

[0024] FIGS. 1 through 4 show various features of a sprocket 100, such as for use in a mobility power system with a toothed belt, usually an “endless” belt. FIG. 1 shows the sprocket 100 with a ring body 102 having a width between a first side 104 and a second side 106 with a plurality of parallel rungs 110 around the outer periphery or circumference of the body 102, each rung 110 having a first end 111 and a second end 112. The first ends 111 of the rungs 110 are present at the first side 104 of the body 102 and the second ends 112 of the rungs 110 are present at the second side 106 of the body 102, so that the rungs 110 extend from the first side 104 to the second side 106. The rungs 110 define the outer circumferential and radial edge of the sprocket 100.SUBSTITUTE SHEET (RULE 26)

[0025] The rungs 110 are placed, sized, and shaped to engage with teeth, particularly between adjacent teeth, on a toothed belt. Present between adjacent rungs 110 is a land 118 (best seen in the enlargement of FIG. 1 and in FIG. 2), which is the trough between the sidewalls of adjacent rungs 110.

[0026] The distance between adjacent rungs 110, which is generally the length of the lands 118 (the width of the lands 118 measured from side 104 to side 106), is equal to or essentially equal to (e.g., a little less, e.g., a little more) than the pitch length of the belt (the approximate length of a tooth) with which the sprocket will engage. The rungs 110 are evenly spaced around the circumference of the sprocket 100. This distance between rungs 110 may be adjusted based on the sprocket diameter, the width of the rungs 110 (measured orthogonal to the direction between the first end 111 and the second end 112) and on the wrap angle of the belt around the sprocket 100.

[0027] The sprocket 100 has a width (from the first side 104 to the second side 106) configured for the toothed belt and the belt system in which it is to be installed. The width of the sprocket is no less than the width of the belt but may be greater than the width of the belt.

[0028] The sprocket 100 includes at least one side flange, in this example a first side flange 114 on the first side 104 and a second side flange 116 on the second side 106. Each of the side flange 114, 116 is discontinuous around the circumferential and radial edge of the sprocket 100.

[0029] As seen in FIG. 2, the flange 116 is discontinuous; that is, a section of the flange 116 extends between one pair of rungs 110 but does not extend between the adjacent pair of rungs 110. Specifically, a rung 110a and a rung 110b are connected by a section 116a of the flange 116. The next adjacent rung 110, shown as rung 110c, is not connected to the rung 110b by the flange 116. Rather, the rung 110c is connected to an adjacent rung 1 lOd by another section 116b of the flange 116. In such a manner, the flange 116 is not continuous around the circumference of the sprocket 100, but rather, has gaps, voids, or spans between pairs of rungs 110.

[0030] Returning to FIG. 1, either or both of the flange 114, 116 may be the same height as the rungs 110 or may be greater, e.g., extending above the level of the rungs 110, e.g., at least about 10 mm. In some embodiments, the flange 114, 116 extends above the height of a belt engaged with the sprocket 100. In some embodiments, the flange 114, 116 may be less than the height of the rungs 110, e.g., extending below the level of the rungs.-5-SUBSTITUTE SHEET (RULE 26)

[0031] Clearly seen in FIG. 3 A, both the flange 114 and the flange 116 are not continuous around the circumference of the sprocket 100 and that both have gaps, voids, or spans between pairs of rungs 110. In this embodiment, the gaps, voids, etc. alternate between the sides 104, 106 for the two flanges 114, 116; that is, if the first flange 114 is present between two rungs 110, a gap exists between those two rungs 110 in the second flange 116, and vice versa. FIG. 3B shows a schematic of just the rungs 110 and the flanges 114, 116 illustrating the alternatingly opposing pattern.

[0032] In order to have flanges 114, 116 repeatedly opposingly alternate around the circumferential edges of the sprocket 100, there is an even number of rungs 110. As an example, a sprocket 100 having forty mngs 110 will have twenty flange 114 sections on the first side 104 and twenty flange 116 sections on the second side 106.

[0033] The flanges 114, 116 facilitate tracking of the belt on the sprocket 100 when in operation and inhibit lateral movement of the belt in relation to the sprocket 100. The flanges 114, 116 may abut the side edges of the belt, depending on the width of the sprocket 100 from side 104 to side 106 and the width of the belt, and help improve the engagement of the sprocket 100 with the belt and to mitigate derailment events. In some designs, one or both of the flanges 114, 116 have a tapered portion, with an inflection point or region at or close to the land 118.

[0034] Together, a pair of adjacent rungs 110, the land 118 (seen in FIGS. 1 and 2) in between those rungs 110, and either the flange 114 or the flange 116 form a volume that receives a tooth from a toothed belt when the belt is engaged with the sprocket 100 at that location. When the tooth is engaged with this volume, the lateral access to the volume is via the side 104 or the side 106 opposing a flange (the side that does not have a flange). This lateral access may also provide an additional benefit for debris (e.g., dirt, dust, moisture, etc.) to be removed from the volume. In addition to this lateral access formed by the lack of a flange closing the volume, the sprocket 100 includes a second lateral access that includes a debris-shedding element to facilitate removal of debris from this volume.

[0035] Present in the flange 114, 116, proximate the land 118, is a debris shedding hole or passage through the flange 114, 116, for example seen as hole 120 in FIG. 1, the hole 120 providing lateral fluid communication from the volume between the rungs 110 and the outside of the sprocket 100. Fluid communication from the volume between the rungs 110 and the outside of the sprocket-6-SUBSTITUTE SHEET (RULE 26)100 is also present at the other side where no flange is present, providing bidirectional, lateral debris expulsion.

[0036] FIG. 4, similar to FIG. 3B, shows a schematic of the rungs (not called out) and the flanges 114, 116 illustrating the alternating pattern and also includes the debris holes 120 illustrating (by the arrows) the bidirectional lateral path of debris removal from the volume between the rungs.

[0037] In some designs, a debris hole 120 is not present in every flange 114, 116.

[0038] Turning to FIG. 5, another sprocket 200 is shown, similar to the sprocket 100 and having a body 202, a first side 204 and an opposite second side 206, with rungs 210 extending from the first side 204 to the second side 206, and having a first flange 214 and a second flange 216, both flanges 214, 216 being discontinuous. A land 218 is present between pairs of rungs 210.

[0039] Present in the flange 214, 216, proximate the land 218, is a debris shedding hole or passage 220 through the flange 214, 216, the hole 220 providing fluid communication from the volume between the rungs 210 and the outside of the sprocket 200. Fluid communication from the volume between the rungs 210 and the outside of the sprocket 200 is also present at the other side where no flange is present. An arrow in FIG. 5 represents the direction of debris expulsion from the volume, particularly through the hole 220 in the flange 216 in one direction and through a break in the flange 214 in the other direction. This expulsion of the debris is lateral and bi-directional, out the sides 204, 206 of the sprocket 200. In this sprocket 200, there is no expulsion of any debris from the sprocket 200 in a radially inward direction.

[0040] The land 218 may be relatively flat or may include a channel 219, e.g., at the lowest portion of the volume (e.g., the area farthest from the top of the rungs 210), to facilitate collection and lateral expulsion of debris through the hole 220 and the other (unflanged) side. The channel 219, if present, is present at at least one of the first side 204 and the second side 206 of the sprocket 200, in some embodiments opposite the side 204, 206 having the flange 214, 216; in some embodiments it may extend continuously from the first side 204 to the second side 206. The channel 219 does not provide fluid communication radially inward from the volume, but laterally out. When a belt tooth is present in this volume between the rungs 210, the tooth generally does not occupy the entire volume between the rungs 210 nor the channel 219, allowing debris to exit from-7-SUBSTITUTE SHEET (RULE 26)the volume through the hole 220 and the other side. In some designs of the sprocket, the channel 219 may not be present in every land 218.

[0041] FIGS. 6A and 6B show another embodiment of a debris shedding sprocket having alternating side flanges.

[0042] FIG. 6A shows a sprocket 300, such as for use in a mobility power system with a toothed belt, having a ring body 302 having a thickness between a first side and a second side with a plurality of parallel rungs 310, extending around the circumference of the body 302 with each rung 310 extending from the first side to the second side. The rungs 310 are placed, sized, and shaped to engage with teeth on a toothed belt. Present between adjacent rungs 310 are lands (not called out in FIG. 6A). The body 302 includes a central aperture 305 for mounting the sprocket 300 on a shaft, axle, etc.

[0043] The sprocket 300 includes at least one side flange, in this example a first side flange 314 on the first side and a second side flange 316 on the second side. Each of the side flanges 314, 316 is discontinuous around the circumferential and radial edge of the sprocket 300.

[0044] A section of the flange 314, 316 extends between at least a pair of rungs 310, in some embodiments the flange 314, 316 extends across and connects three or more rungs 310. In such a manner, the flanges 314, 316 are not continuous around the circumference of the sprocket 300, but rather, has gaps, voids, or spans between pairs of rungs 310. Unlike the sprocket 100 of the previous figures that had each flange 114, 116 connecting two rungs 110 and the flanges 114, 116 being symmetrical, the sprocket 300 connects at least two rungs 310, in some locations on the sprocket 300 more than two rungs 310. Such a flange pattern may be with an even number of rungs 310 or with an odd number of rungs 310 on the sprocket 300. FIG. 6B shows a schematic of just the rungs 310 and the flanges 314, 316 illustrating the alternatingly opposing asymmetrical pattern.

[0045] The section of outer periphery shown in FIG. 6B has ten rungs 310 shown. From left to right in the figure, the first four rungs 310 are connected via a section of flange 314, the fourth, fifth and sixth rungs 310 are connected via a section of the flange 316, and the sixth through tenth rungs 310 are connected via another section of the flange 314.

[0046] Together, a pair of adjacent rungs 310, the land in between those rungs 310, and either the flange 314 or the flange 316 form a volume that receives a tooth from a toothed belt when-8-SUBSTITUTE SHEET (RULE 26)the belt is engaged with the sprocket 300. The sprocket 300 includes a debris-shedding element to facilitate removal of debris from this volume.

[0047] Present in the flange 314, 316 is a debris shedding hole or passage 320 providing fluid communication from the volume between the rungs 310 and the outside of the sprocket 300. For sections of flange spanning more than two rungs 310, one hole 320 may be present between each pair of rungs 310 or one hole 320 may span across multiple volumes formed by pairs of rungs 310. Fluid communication from the volume between the rungs 310 and the outside of the sprocket 300 is also present at the other side where no flange is present. This open side of the volume (the side of the volume not having a flange) and the hole in the flange at the other side of the volume provide expulsion of debris from the volume laterally and bi-directionally, out the sides of the sprocket 300.

[0048] The sprockets 100, 200, 300 described previously are hub-less sprockets. In other words, the sprocket 100, 200, 300 is connected or secured to a crank assembly or motor shaft, e.g., via a plurality of bolts passing through apertures in the body 102, 202 302. Alternately, the sprocket 100, 200, 300 can be fastened to a wheel hub. Both sprockets 100, 200 include five apertures for receiving fasteners (e.g., bolts) therethrough. These hub-less sprockets 100, 200, 300 are typically formed by a single process (e.g., machining, molding, casting, etc.). FIGS. 7A and 7B illustrate an alternate, hubbed, sprocket formed by a two-step process.

[0049] In FIG. 7 A, a sprocket 400 similar to the sprocket 100 is shown, having a body 402 with sides 404, 406, peripheral rungs 410 and symmetrical alternating flanges 414, 416. A debris shedding hole 420 is located in each of the flanges 414, 416 to provide lateral expulsion of debris from between adjacent rungs 410. In this sprocket 400, the inner surface 405 is formed by a previously-formed core, insert or hub 408 that interfaces the body 402, as seen in FIG. 7B The body 402 can be formed over the hub 408 in an overmold manner, or the hub 408 may be molded simultaneously with or subsequent to the body 402. The hub 408 may be formed of a metal (e.g., steel, powdered metal) or polymer composite with sufficient application-specific strength and hardness to nominally transmit torque from the body 402 through the hub 408 to the inner surface 405. The inner surface 405 of the hub 408 can be e.g., 3-lobe, 6-lobe, 9-spline, ISO threaded, etc. and may be used to seat the sprocket 400 onto a variety of shafts or axles, e.g., via a bushing.

[0050] FIG. 8 shows an embodiment of a debris shedding sprocket having at least one discontinuous side flange. A sprocket 500, such as for use in a mobility power system with a-9-SUBSTITUTE SHEET (RULE 26)toothed belt, has a ring body 502 having a thickness between a first side 504 and a second side 506 with a plurality of parallel rungs 510, extending around the circumference of the body 502 with each rung 510 extending from the first side 504 to the second side 506. The rungs 510 are placed, sized, and shaped to engage with teeth on a toothed belt. Present between adjacent rungs 510 are lands (not called out in FIG. 8).

[0051] The sprocket 500 includes at least one side flange, in this example a first side flange 514 on the first side and a second side flange 516 on the second side. The side flange 514 is continuous around the circumference and radial edge of the sprocket 500, whereas the side flange 516 is discontinuous. For the continuous flange 514, the flange 514 extends between and connects all of the rungs 510, whereas for the discontinuous flange 516, sections of the flange 516 extends between pairs of rungs 510. In this particular embodiment, the continuous flange 514 has a higher height and extends farther above the rungs 510 than the discontinuous flange 516.

[0052] The sprocket 500 includes a debris-shedding element to facilitate removal of debris from the volume formed by the rungs 510 and the flanges 514, 516.

[0053] Present in the flange 514, 516 is a debris shedding hole or passage 520 providing fluid communication from the volume between the rungs 510 and the outside of the sprocket 500. Fluid communication from the volume between the rungs 510 and the outside of the sprocket 500 is also present at the other side where no flange is present. This open side of the volume (the side of the volume not having a flange) and the hole in the flange at the other side of the volume provide expulsion of debris from the volume laterally and bi-directionally, out the sides of the sprocket 500.

[0054] Because the flange 514 is continuous, unlike the flange 516 which is discontinuous, the flange 514 has a larger debris-shedding hole 520a for those volumes that are bound by the flange 516 and has a smaller debris-shedding hole 520b for those volumes that are open at the side 506 (that is, not having the flange 516). Of course, other designs are possible and are suitable.

[0055] FIG. 9 shows another sprocket, a sprocket 600. Similar to the other sprockets discussed above, the sprocket 600 has a ring body 602 having a width between a first side 604 and a second side 606 with a plurality of parallel rungs 610 around the outer periphery or circumference of the body 602, each rung 610 having a first end 611 and a second end 612. The sprocket 600 includes has a first side flange 614 on the first side 604 and a second side flange 616 on the second-10-SUBSTITUTE SHEET (RULE 26)side 606. Each of the side flanges 614, 616 is discontinuous around the circumferential and radial edge of the sprocket 600.

[0056] Together, a pair of adjacent rungs 610 and either the flange 614 or the flange 616 form a volume that receives a tooth from a toothed belt when the belt is engaged with the sprocket 600 at that location. Lateral access to this volume is via the side 604 or the side 606 opposing a flange (the side that does not have a flange) and also via a debris shedding hole or passage 620 through the flange 614, 616. The hole 620 and the lack of a flange provide bi-directional lateral fluid communication from the volume between the rungs 610 to external to the sprocket 600.Additionally, in this design, fluid communication from the volume is also provided in a radially inward direction, by, e.g., chamfered lands between the rungs 610, and by the holes 620 which wrap around the flanges 614, 616 and have an inward radial component.

[0057] The sprockets 100, 200, 300, 400, 500, 600 and variations thereof described herein can generally be manufactured using any known and suitable technique. For example, the sprockets may be machined, molded (e.g., injection molded), die cast, or 3D printed.

[0058] Examples of suitable materials for the sprockets 100, 200, 300, 400, 500, 600 and variations thereof include thermoplastic and / or thermoset polymer(s) (e.g., polycarbonate, polyamide, polyethylene, polyphthalamide), including fiber-reinforced polymers, metal (e.g., steel, stainless steel, nickel, iron, aluminum, alloys), and composite materials. The sprockets 100, 200, 300, 400, 500, 600 and variations thereof could be molded, cast, 3D printed, or otherwise formed.

[0059] Thus, described herein is at least one specific example of a sprocket having at least one non-continuous flange with a debris-shedding element therein.

[0060] The above specification and examples provide a complete description of the structure and use of exemplary implementations of the invention. The above detailed description, therefore, is not to be taken in a limiting sense. It is to be understood that other implementations are contemplated and may be made without departing from the scope or spirit of the present disclosure. For example, the embodiments illustrated in FIGS. 1, 8 and 9 have five apertures for engaging the sprocket 100, 500, 600 with the crank assembly or motor shaft; other numbers of apertures may be used, e.g., three (3), four (4), six (6), etc. As another example, the embodiment of FIG. 1 has opposingly alternate flanges 114, 116, each flange section spanning two rungs 110; other numbers-11-SUBSTITUTE SHEET (RULE 26)of rungs may be spanned in an opposingly alternate manner. Also, the embodiment of FIGS. 6A and 6B has a particular opposingly asymmetric flange configuration; other configurations may be used. Also, as a variant, any of the sprockets may include a pair of rungs having no flange therebetween; but rather, the volume between the rungs is unbounded laterally. As another example, any of the sprockets 100, 200, 300, 400, 500, 600 and variations thereof may include strengthening ribs, e.g., to increase the rigidity of the flange(s) or the overall sprocket.

[0061] Additionally, elements or features of one example, embodiment or implementation may be applied to any other example, embodiment or implementation described herein to the extent such contents do not conflict. The above detailed description, therefore, is not to be taken in a limiting sense.

[0062] While the present disclosure is not so limited, an appreciation of various aspects of the disclosure will be gained through a discussion of the examples provided.

[0063] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties are to be understood as being modified by the term “about,” whether or not the term “about” is immediately present. Accordingly, unless indicated to the contrary, the numerical parameters set forth are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein.

[0064] As used herein, the singular forms “a”, “an”, and “the” encompass implementations having plural referents, unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and / or” unless the content clearly dictates otherwise.

[0065] Spatially related terms, including but not limited to, “bottom,” “lower”, “top”, “upper”, “beneath”, “below”, “above”, “on top”, “on,” etc., if used herein, are utilized for ease of description to describe spatial relationships of an element(s) to another. Such spatially related terms encompass different orientations of the device in addition to the particular orientations depicted in the figures and described herein. For example, if a structure depicted in the figures is turned over or flipped over, portions previously described as below or beneath other elements would then be above or over those other elements.-12-SUBSTITUTE SHEET (RULE 26)

Claims

CLAIMS1. A sprocket compri sing : a plurality of rungs each having a first end and a second end, the first ends of the rungs at a first side of the sprocket and the second ends of the rungs at a second side of the sprocket; a land between each pair of rungs; a first circumferential flange at the first side that is discontinuous, and a second circumferential flange at the second side, each of the first flange and the second flange having a plurality of debris shedding holes therethrough, a debris shedding hole located between each pair of rungs.

2. The sprocket of claim 1 further comprising a channel in the land present at at least one of the first side and the second side, with the debris shedding hole located proximate the channel.

3. The sprocket of claim 1 or 2, wherein the second flange is continuous.

4. The sprocket of claim 1 or 2, wherein the second flange is discontinuous.

5. The sprocket of claim 4, wherein the first flange and the second flange are symmetrically opposingly discontinuous.

6. The sprocket of claim 4, wherein the first flange and the second flange are asymmetrically opposingly discontinuous.

7. The sprocket of claim 1, wherein the first flange comprises a plurality of flange sections, each section extending between one pair of rungs.

8. The sprocket of claim 7, wherein the second flange is discontinuous and comprises a plurality of flange sections that each extends between one pairs of rungs, with the first flange and the second flange alternatingly opposed.-13-SUBSTITUTE SHEET (RULE 26)9. The sprocket of claim 8, wherein the first flange and the second flange are symmetrically alternatingly opposed.

10. The sprocket of claim 1, wherein: the first flange comprises a plurality of flanges sections, each section extending between multiple pairs of rungs; the second flange comprises a plurality of flanges sections, each section extending between multiple pairs of rungs, and the first flange and the second flange are asymmetrically alternatingly opposed.

11. The sprocket of claim 2, wherein the channel in the land extends from the first side to the second side.

12. A sprocket compri sing : a plurality of rungs extending from a first side of the sprocket to a second side of the sprocket, with a land present between the rungs; a first circumferential flange at the first side; a second circumferential flange at the second side; a volume defined by two adjacent rungs, the land therebetween, the first side, and the second side, and a first debris shedding element at the first side of the volume and a second debris shedding element at the second side of the volume, the debris shedding elements providing bidirectional lateral fluid communication from the volume to external to the sprocket, with no inwardly radial fluid communication from the volume to external to the sprocket.

13. The sprocket of claim 12, wherein the first circumferential flange has a gap, so that the volume is defined by two adjacent rungs, the land therebetween, the gap at the first side, and the flange at the second side, the flange at the second side having a hole therethrough providing the second debris shedding element and the gap at the first side providing the first debris shedding element.-14-SUBSTITUTE SHEET (RULE 26)14. The sprocket of claim 12, the land further including a lateral channel therein extending from the first debris shedding element to the second debris shedding element.

15. A belt drive system comprising: a belt having a plurality of longitudinally spaced belt teeth; and a sprocket, the sprocket comprising a plurality of rungs each having a first end and a second end, the first ends of the rungs at a first side of the sprocket and the second ends of the rungs at a second side of the sprocket; a land between each pair of rungs; a first circumferential flange at the first side that is discontinuous, and a second circumferential flange at the second side, each of the first flange and the second flange having a plurality of debris shedding holes therethrough, a debris shedding hole located between each pair of rungs.

16. The system of claim 15 further comprising a channel in the land extending from at least one of the first side and the second side, with the debris shedding hole located proximate the channel.

17. The system of claim 15, wherein the second flange is discontinuous.

18. The system of claim 17, wherein the first flange and the second flange are symmetrically opposingly discontinuous.

19. The system of claim 17, wherein the first flange and the second flange are asymmetrically opposingly discontinuous.

20. The system of claim 15, wherein the first flange comprises a plurality of flange sections each section extending between one pair of rungs.

21. The system of claim 20, wherein the second flange is discontinuous and comprises a plurality of flange sections that each extend between one pair of rungs, with the first flange and the second flange alternatingly opposed.-15-SUBSTITUTE SHEET (RULE 26)22. The system of claim 17, wherein: the first flange comprises a plurality of flanges sections, each section extending between multiple pairs of rungs; and the second flange comprises a plurality of flanges sections, each section extending between multiple pairs of rungs.

23. The system of claim 22, wherein the first flange and the second flange are asymmetrically alternatingly opposed.

24. A belt drive system comprising: a belt having a plurality of longitudinally spaced belt teeth; a first sprocket accompanying a crank, the first sprocket comprising a plurality of rungs each having a first end and a second end, the first ends of the rungs at a first side of the sprocket and the second ends of the rungs at a second side of the sprocket; a first circumferential flange at the first side that is discontinuous, and a second circumferential flange at the second side, each of the first flange and the second flange having a plurality of debris shedding holes therethrough, a debris shedding hole located between each pair of rungs; and a second sprocket accompanying a driven shaft.-16-SUBSTITUTE SHEET (RULE 26)

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