WO2013016381A2

WO2013016381A2 - Belt drive pulley with a non-integrally formed centering flange

Info

Publication number: WO2013016381A2
Application number: PCT/US2012/048054
Authority: WO
Inventors: Andrew LUMPKIN; Wayne Lumpkin
Original assignee: Alto Designs, Llc
Priority date: 2011-07-27
Filing date: 2012-07-25
Publication date: 2013-01-31
Also published as: TW201328933A; WO2013016381A3

Abstract

A pulley for use with a belt drive, the drive belt comprising a plurality of longitudinally spaced inner lugs each having an alignment groove dividing each lug into first and second segments. The pulley comprises a circular frame configured to rotate about a rotation axis. A plurality of circumferential teeth extend radially and axially of a peripheral edge of the circular frame. Each tooth is configured to be received between adjacent inner lugs of the drive belt. A tooth groove is provided in each of the teeth. The tooth groove is configured to align with the alignment groove of the drive belt. A circular alignment flange formed separately from the circumferential teeth is received in the tooth grove of each tooth. With the circular alignment flange received in the tooth groove of each tooth, the alignment flange is received in the alignment groove of a drive belt operatively associated therewith.

Description

Attorney Docket: 0398.01PCT

BELT DRIVE PULLEY WITH A NON-INTEGRALLY

FORMED CENTERING FLANGE

TECHNICAL FIELD

[0001] Belt drive systems, and more particularly, a belt drive pulley with a non- integrally formed centering flange.

BACKGROUND

[0002] U.S. Patent Publication No. US 2011/0049831, entitled "Belt Drive System," the contents of which are hereby incorporated by reference in their entirety, discloses a self- aligning belt drive system comprising a drive belt having a plurality of longitudinally spaced inner lugs each having an alignment groove. The system further includes at least one pulley comprising a frame. A plurality of circumferential teeth extend radially and axially of the pulley rim with each tooth being configured to be received between adjacent inner lugs of the drive belt. An alignment flange extends radially between circumferential teeth. The alignment flange is configured to be received in the alignment groove. In the system disclosed in the '831 publication, the alignment flange is illustrated as being integrally formed with the teeth of the pulley. While having some advantages, integrally forming the alignment flange with the teeth can unduly complicate the manufacturing process and increase costs.

[0003] The present invention is directed toward overcoming one or more of the problems discussed above.

SUMMARY

[0004] A first aspect is a pulley for use with a belt drive. The drive belt comprises a plurality of longitudinally spaced inner lugs each having an alignment groove dividing each lug into first and second segments. The pulley comprises a circular frame configured to rotate about a rotation axis. A plurality of circumferential teeth extend radially and axially of a peripheral edge of the circular frame. Each tooth is configured to be received between adjacent inner lugs of the drive belt. A tooth groove is provided in each of the teeth. The tooth groove is configured to align with the alignment groove of the drive belt. A circular alignment flange formed separately from the circumferential teeth is received in the tooth grove of each tooth. With the circular alignment flange received in the tooth groove of each tooth, the alignment flange is received in the alignment groove of a drive belt operatively associated therewith.

[0005] The alignment flange may, for example, comprise two or more circular segments which are joined together at their distal ends. Alternatively, the alignment flange may comprise a single or multiple turn flat wire spiral coil.

[0006] A second aspect is a self-aligning pulley and drive belt system comprising a drive belt as described in the preceding paragraph and a pulley as described in the preceding paragraph.

[0007] Yet another aspect is a bicycle comprising a crank set, a rear wheel hub and a pulley and drive belt system as described in the preceding paragraph with a first pulley operatively associated with the crank set, a second pulley operatively associated with the hub and an inner surface of the drive belt engaging each of the first and second pulleys.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Fig. 1 is a schematic plan view of a cycle, in particular a bicycle including a pulley and drive belt system;

[0009] Fig. 2 is a perspective view of the second pulley of Fig. 1 ;

[0010] Fig. 3 is a cross-section of the second pulley of Fig. 2 taken along line 3-3;

[0011] Fig. 4 is a perspective view of the cross-section of Fig. 3;

[0012] Fig. 5 is a perspective view of the first and second pulleys of Fig. 1 engaged with a drive belt;

[0013] Fig. 6 is a side elevation view of the pulley and drive belt system of Fig. 5;

[0014] Fig. 7 is a cross-section of the second pulley of Fig. 6 taken along line 7-7 of

Fig. 6;

[0015] Fig. 8 is a cross-section of a segment of a pulley illustrating an axial offset; and

[0016] Fig. 9 is a cross-section of a belt lug-pulley tooth engagement;

[0017] Fig. 10 is a front elevation view of a pulley with a non-integrally formed centering flange;

[0018] Fig. 11 is a perspective view of the pulley of Fig. 10;

[0019] Fig. 12 is a side elevation view of the pulley of Fig. 10;

[0020] Fig. 13 is a side elevation view of the pulley of Fig. 10 with the non-integrally formed centering flange illustrated disassociated from the pulley body; [0021] Fig. 14 is a perspective view of the pulley of Fig. 10 with the non- integrally formed centering flange illustrated disassociated from the pulley body;

[0022] Fig. 15 is a sectional view of the pulley of Fig. 10 illustrating the non- integrally formed centering flange received in a tooth groove of each of the pulley teeth; and

[0023] Fig. 16 a perspective view of spiral coil retaining ring suitable for use with the pulley of Fig. 10.

DETAILED DESCRIPTION

[0024] Unless otherwise indicated, all numbers expressing quantities of ingredients, dimensions reaction conditions and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about".

[0025] In this application and the claims, the use of the singular includes the plural unless specifically stated otherwise. In addition, use of "or" means "and/or" unless stated otherwise. Moreover, the use of the term "including", as well as other forms, such as "includes" and "included", is not limiting. Also, terms such as "element" or "component" encompass both elements and components comprising one unit and elements and components that comprise more than one unit unless specifically stated otherwise.

[0026] A. Representative Belt Drive System

[0027] This section of the application describes a representative belt drive system which is fully described in U.S. Patent Publication No. US 2011/0049831. The belt drive system described herein has application to a wide variety of apparatus utilizing belt drives, including, but not limited to, cycles such as motorcycles and bicycles. Because of the particular advantages of the belt drive system for use with bicycles, the belt drive system is illustrated herein in use with a bicycle. This specific embodiment is intended to be non- limiting unless expressly limited by the scope of the attached claims.

[0028] A bicycle 10 having a drive belt system 12 is schematically illustrated in Fig.

1. The bicycle 10 includes a frame 14 with a rear wheel 16 having a hub 18 attached to the frame by a rear drop out (not shown). The bicycle 10 further includes a crank set 20. The belt drive system 12 includes a first pulley 22, which is operatively associated with the crank set 20 to rotate about a common rotation axis with the crank set 20. A second pulley 24 is operatively associated with the rear wheel hub 18 to rotate about a common rotation axis. A synchronous drive belt 26 extends between the first pulley 22 and the second pulley 24. As illustrated in Fig. 1 the first pulley 22 may have a diameter greater than the second pulley. In other embodiments the pulleys may be of the same size or the second pulley may have a diameter greater than the first pulley. In addition, one or more additional coaxial pulleys may be provided adjacent the first or second pulley to provide for varying gear ratios. Such an embodiment may further include a front or rear derailleur to enable shifting between adjacent pulleys. Or gearing may be provided by means of geared rear hub of the type known in the art.

[0029] Fig. 2 is a perspective view of the second pulley 24 removed from the hub 18 and the belt drive system 12. Figs. 3-4 present different views of the second pulley 24. The second pulley 24 comprises a frame 28 configured for connection to the hub 18 of the rear wheel 16 and includes a circular outer rim 30 with opposing sides 32, 34, a hub connection ring 36 and a support structure connecting the hub to the outer ring, for example, the plurality of spokes 37 extending between the hub connection ring 36 and the circular outer rim 30. The second pulley 24 further comprises a plurality of circumferential teeth 38. As illustrated, the circumferential teeth are evenly spaced at a pulley pitch PP and extend radially and axially of the rim. In other embodiments, the teeth may have variable spacing to mate with a drive belt having variably spaced lugs.

[0030] Each tooth further has a width W parallel to the rotation axis. The width W is at least equal to the width of the drive belt 26, though in some embodiments it may be equal, more or less than the width of the drive belt. It can be advantageous for the tooth width and belt width to be substantially equal to maximize the amount of force transmitted between the belt and teeth while minimizing the respective width of the belt and teeth. Each tooth 38 is configured to be received in a space between adjacent inner lugs 42 of a drive belt 26 as illustrated in Figs. 5 and 6. In some embodiments, as illustrated in Figs. 5 and 6, the teeth substantially fill the space between adjacent lugs. This feature can be useful to minimize slippage between the belt and pulley if the direction of rotation of the pulley reverses. These inner lugs are spaced a belt pitch BP. The second pulley 24 includes an alignment flange 44 extending between adjacent circumferential teeth. The alignment flange 44 is configured to be received in an alignment groove 46 of the drive belt 26, which divides each lug into first and second lug segments. See Figs. 5-7. Referring to Fig. 7, the alignment groove 46 can have parallel side walls. In other embodiments the side walls can be tapered to facilitate receiving the alignment flange 44 therein. Furthermore, the alignment flange 44 may be tapered to facilitate mating with the centering groove. Whether tapered or not, alignment flange 44 may further include a distal end that is rounded or otherwise configured to facilitate such mating. In the illustrated embodiment and as seen in Fig. 7, the alignment groove 46 divides the lugs 42 into equal first and second lug segments. However, the first and second lug segments could be of different widths in other embodiments. In the illustrated embodiment, each tooth of the second pulley 24 extends lengthwise an equal distance from each side of the rim. In embodiments where the first and second lug segments are of different widths, the teeth would generally have corresponding different widths. In the illustrated embodiment, each tooth of the second pulley 24 extends radially beyond the alignment flange 44 from the rotation axis (see Fig. 6), though in other embodiments they can extend the same distance or the alignment flange 44 could extend further. In some embodiments the circumferential teeth, the alignment flange and the alignment groove are configured so that with the alignment flange received in the alignment groove, the drive belt rides on the circumferential teeth. Alternatively, the circumferential teeth, the alignment flange and the alignment groove may be configured to also ride on the alignment flange.

[0031] Fig. 9 illustrates an embodiment wherein the alignment flange has parallel sidewalls and a rounded distal end. In this embodiment the pulley has a width H of about 11 mm and the teeth have a width of about 11 mm. In most embodiments the width of the teeth is at least equal to the width of the belt. In Fig. 9, the alignment groove has a width I of about 1.5 mm and the alignment flange has a width J of about 1.0 mm. Generally the alignment groove width is slightly larger than the alignment flange width to provide some engagement clearance, but should not be so much wider to allow the belt to wander an undesirable amount along the width of the teeth. Generally, the width of the alignment groove is minimized to maximize the amount of belt surface available to engage the teeth and maximize the surface for force transmission there between. Minimizing the width of the alignment groove also minimizes the likelihood of debris entering the alignment groove. Assuming a belt width of about 11 mm, in some embodiments an alignment groove width may be between about 1 -3 mm, in other embodiments about 1-2 mm and in other embodiments about 1-1.5 mm. The alignment flange generally would have a width of about 0.5 mm less than the alignment groove.

[0032] In some embodiments the ratio of the width of the alignment groove to the belt width can be as great as 1 :3. In other embodiments it can be 1 :4. In still other embodiments it can be 1 :8, 1 : 10 or even smaller. The ratio of the width of the alignment flange to the width of the teeth can also be 1 :3, 1 :4, 1 : 10 or even smaller.

[0033] As seen in Fig. 9, the alignment flange is configured so that it does not extend to the bottom of the alignment groove. In the embodiment of Fig. 9 there is a distance of about 0.75 mm between the distal end of the flange and the bottom of the alignment groove. This configuration is useful where the belt and pulley drive system is used in an environment where debris may be present, such as mountain biking. This space provides for accumulation of some debris without filling the alignment groove and possibly forcing the belt off the pulley. In other applications where debris accumulation is of little concern, the alignment flange can be configured to extend the full depth of the alignment groove. In most embodiments it is desirable that the alignment flange not extend so far into the alignment groove that the belt rides on the alignment flange to the exclusion of the surface of the pulley teeth.

[0034] The present application describes a pulley having a non-integral centering flange for use with a belt drive system 12 of the type described above. The pulley with non- integral centering flange may have any of the attributes of the pulleys described above and is intended for use with any of the embodiments disclosed in above.

[0035] B. Belt Drive Pulley with a Non-Integrally Formed Centering Flange

[0036] A pulley with non-integral centering flange 100 is illustrated in Fig. 10. This pulley is very similar to the pulleys described above and the same reference numbers are used in Fig. 10. Briefly, the pulley 100 comprises a frame 28 configured for connection to the hub of a wheel and includes a circular outer rim 30, a hub connection ring 36 and a plurality of spokes 37 extending between the hub connection ring 36 and the circular outer rim 30. The pulley 100 further comprises a plurality of circumferential teeth 38. As illustrated, the circumferential teeth 38 are evenly spaced and extend radially and axially of the rim. This is perhaps best viewed in Fig. 11. The circumferential teeth 38 are substantially identical to those described in Section A above, only each tooth has a tooth groove 102 which is configured to align with an alignment groove of a drive belt of the type described in detail above. Figs. 13 and 14 best illustrate the tooth grooves 102. In Figs. 10-12, a circular alignment flange 104 is shown received in the tooth groove 102 of each tooth. As seen in Figs. 1-3, the circular alignment flange 104 extends radially no further than the

circumferential teeth 38 from a rotation axis of the pulley 100. In other embodiments, the circular alignment flange may extend the same distance and in other embodiments it may extend further from the rotation axis than the circumferential teeth 38.

[0037] Figs. 13 and 14 illustrate that the circular alignment flange 104 is formed separately from (i.e., is "non-integrally formed" with) the circumferential teeth 38 of the pulley 100. The circular alignment flange 104 can take many forms. For example, it could be made of two or more segments of a circular ring joined together with the ends of adjacent segments into a circular alignment flange. The segments could be joined by any suitable means. For example, if the segments are metallic they can be joined by spot welds, rivets, screws, adhesives or other suitable structures. If the segments are plastic, they could be joined by and adhesives. In the embodiment illustrated herein, the circular alignment flange 104 comprises substantially planar sidewalls. The planar sidewalls may be parallel to one another. In the illustrated embodiment, the circular alignment flange 104 comprises a two- turn flat wire spiral coil configured to have a substantially uniform width in part by utilizing a bend in the circular coil where the ends of the circular coil meet. This is illustrated, for example, by the Sprilox® retaining ring 108 shown in Fig. 16. Alternate embodiments of the circular alignment flange 104 could include a single-turn flat wire coil or a three-turn or more-turn flat wire spiral coil. One known source of suitable flat wire spiral coils for use as the alignment flange is the Smalley Steel Ring Company. An example of a suitable Smalley offering is their Sprilox® retaining rings. Other suitable rings could include Smalley constant section rings or wave rings.

[0038] In use, the pulley with non- integral centering flange 100 is constructed by the pulley body 106 first being formed by known techniques, such as molding, forging or CNC machining. Once formed, the circular alignment flange 104 which can be in the form of a flat wire spiral coil is manipulated to enlarge its internal diameter and slipped over the pulley body with the flat wire spiral coil aligned with the tooth grooves 102. The flat wire spiral coil is released and self -biased to assume an inner diameter which retains it within the tooth grooves 102. The circular alignment flange 104 then functions in the identical manner as the alignment flange described in Section A above.

[0039] The circular alignment flange 104 could be formed by other methods. For example, the circular alignment flange 104 could comprise at least two circle segments which together form an entire circle. These circle segments can be received in the tooth grooves 102 and then welded together to form the circular alignment flange 104 and to retain them within the tooth grooves 102. Other forms of non-integral alignment flanges are within the scope of the invention as the broadest concept of the invention is that of providing a non- integral circular alignment flange in combination with a pulley body 106 having tooth grooves 102 as described herein. In some embodiments the alignment flange is simply received within the tooth grooves and is not otherwise secured to the pulley body. In other embodiments the alignment flange may be welded, for example, spot welded, sonic welded or the like to the pulley body 106. Various adhesives or attachment devices such as screws, bolts, pins and the like, could also be used to affix the alignment flange to the pulley body with the alignment flange received in the tooth grooves 102. [0040] One advantage of a non-integral alignment flange is it simplifies the manufacture of the pulley body. Thus, even though requiring a second independent part to be assembled, use of the non-integral alignment flange can actually reduce manufacturing time and attendant costs. The non-integral alignment flange and pulley body as well as the assembled pulley 100 can have any of the attributes of the alignment flange and pulley as well as the elements of any embodiment and application of the pulley system described in in Section A. For example, and not by way of limitation, a bicycle including the pulley 100.

[0041] Various embodiments of the disclosure could also include permutations of the various elements recited in the claims as if each dependent claim was a multiple dependent claim incorporating the limitations of each of the preceding dependent claims as well as the independent claims. Such permutations are expressly within the scope of this disclosure.

[0042] While the invention has been particularly shown and described with reference to a number of embodiments, it would be understood by those skilled in the art that changes in the form and details may be made to the various embodiments disclosed herein without departing from the spirit and scope of the invention and that the various embodiments disclosed herein are not intended to act as limitations on the scope of the claims. All references cited herein are incorporated in their entirety by reference.

Claims

CLAIMS What is claimed is:

1. A pulley for use with a drive belt, the drive belt comprising a plurality of longitudinally spaced inner lugs each having an alignment groove dividing each lug into first and second lug segments, the pulley comprising:

a circular frame configured to rotate about a rotation axis;

a plurality of circumferential teeth extending radially and axially of a peripheral edge of the circular frame, each tooth being configured to be received between adjacent inner lugs of the drive belt;

a tooth groove in each of the teeth, the tooth groove being configured to align with the alignment groove of the drive belt; and

a circular alignment flange formed separately from the circumferential teeth received in the tooth grove of each tooth, wherein with the circular alignment flange received in the tooth groove of each tooth, the alignment flange is received in the alignment groove of a drive belt operatively associated therewith.

2. The pulley of claim 1 wherein the circular alignment flange extends radially no further than the circumferential teeth from the rotation axis.

3. The pulley of claim 1 wherein the alignment flange comprises substantially planar side walls.

4. The pulley of claim 1 wherein the alignment flange comprises a single turn flat wire spiral coil.

5. The pulley of claim 1 wherein the alignment flange comprises a 2-turn flat wire spiral coil.

6. The pulley of claim 1 wherein the alignment flange comprises a 3 -turn or more flat wire spiral coil.

7. The pulley of claim 1 wherein the alignment flange comprises at least two circle segments welded together while received in the tooth groove of each tooth.

8. The pulley of claim 1 further comprising the circular alignment flange having a width less than 1/3 the width of the teeth.

9. A self-aligning pulley and drive belt system comprising:

a drive belt, the drive belt comprising a plurality of longitudinally spaced inner lugs each having a an alignment groove dividing the lug into first and second lug segments, the alignment groove having an alignment groove depth; and

a pulley comprising:

a circular frame configured to rotate about a rotation axis;

a plurality of circumferential teeth extending radially and axially of a peripheral edge of the circular frame, and each tooth being configured to be received between adjacent inner lugs of the drive belt;

a tooth groove in each of the teeth, the tooth groove being configured to align with the alignment groove; and

a circular alignment flange formed separately from the circumferential teeth received in the tooth grove of each tooth, whereby with the circular alignment flange received in the tooth groove of each tooth the alignment flange is received in the alignment groove of the drive belt.

10. The system of claim 9 wherein the alignment flange extends no further radially from the rotation axis than the circumferential teeth.

11. The system of claim 9 wherein the alignment flange and the alignment groove are configured so that with the alignment flange received in the alignment groove, the drive belt rides on the circumferential teeth.

12. A bicycle comprising:

a crank set;

a rear wheel hub; and

a pulley and drive belt system operatively associated with the crank set and the rear wheel hub, the pulley and drive belt system comprising:

a drive belt, the drive belt comprising a plurality of longitudinally spaced inner lugs each having a an alignment groove dividing each lug into first and second lug segments; and a first pulley operatively associated with the crank set configured to engage the inner surface of the drive belt, the first pulley comprising:

a circular frame configured to rotate about a rotation axis of the crank set;

a plurality of circumferential teeth extending radially and axially of a peripheral edge of the circular frame, and each tooth being configured to be received between adjacent inner lugs of the drive belt; a tooth groove in each of the teeth, the tooth groove being configured to align with the alignment groove; and

a circular alignment flange formed separately from the circumferential teeth received in the tooth groove of each tooth, whereby with the circular alignment flange received in the tooth groove of each tooth the alignment flange is received in the alignment groove of the drive belt; and

a second pulley operatively associated with the hub configured to engage the inner surface of the drive belt, the second pulley comprising:

a circular frame configured to rotate about a rotation axis of the hub;

a plurality of circumferential teeth extending radially and axially of a peripheral edge of the circular frame, each tooth having a tooth width at least equal to a width of the drive belt, and each tooth being configured to be received between adjacent inner lugs of the drive belt;