DRIVE CHAIN SYSTEM

Abstract

A drive chain system having a chain with an alternating succession of inner chain links and outer chain links, each inner chain link having a pair of inner link plates and each outer chain link having a pair of two outer link plates contacting the inner link plates of adjacent inner chain links. A pin connects two outer link plates and two inner link plates, wherein the inner surfaces of a pair of opposite outer link plates has protrusions in the area between the adjacent inner link plates. The system has a rear cassette with a multitude of sprockets with a plurality of sprocket teeth, wherein the cassette has sprocket teeth of different tooth types, the teeth of at least one tooth type having a tip laterally offset from the centerplane.

Claims

1. A drive chain system comprising a chain with an alternating succession of inner chain links and outer chain links, each inner chain link having a pair of inner link plates and each outer chain link having a pair of two outer link plates contacting the inner link plates of adjacent inner chain links, wherein a pin connects two outer link plates and two inner link plates, wherein the inner surfaces of a pair of opposite outer link plates comprise protrusions in the area between the adjacent inner link plates, wherein the system comprises a rear cassette with a multitude of sprockets with a plurality of sprocket teeth, wherein the cassette comprises sprocket teeth of different sprocket tooth types, the sprocket teeth of at least one sprocket tooth type having a tip laterally offset from the respective centerplane.

2. The system according to claim 1, wherein the at least one sprocket tooth type is an upshifting sprocket tooth type supporting shifting to a larger sprocket, the upshifting sprocket teeth of this upshifting sprocket tooth type having a tip laterally offset towards a smaller sprocket.

3. The system according to claim 2, wherein the cassette comprises upshifting sprocket teeth of at least two different upshifting sprocket tooth types supporting shifting to a larger sprocket, wherein the distance by which the tips of the at least two upshifting sprocket tooth types are offset towards the smaller sprocket being different between the at least two upshifting sprocket tooth types.

4. The system according to claim 2, wherein the upshifting sprocket teeth of the at least one upshifting sprocket tooth type having on their side facing a smaller sprocket a taper of the tooth towards the tip.

5. The system according to claim 4, wherein the taper is at an angle (α) of at least 5°, and/or maximum 45°, to a plane parallel to the centerplane of the respective upshifting sprocket tooth.

6. The system according to claim 2, wherein the teeth of the at least one upshifting sprocket tooth type have an inclined surface between their side facing a larger sprocket and the tip.

7. The system according to claim 6, wherein the inclined surface is at an angle (β) of at least 100° and/or maximum 170°, to a plane parallel to the centerplane of the respective tooth.

8. The system according to claim 1, wherein the at least one sprocket tooth type is a downshifting sprocket tooth type supporting shifting to a smaller sprocket, the downshifting sprocket teeth of this tooth type having a tip laterally offset towards a larger sprocket.

9. The system according to claim 8, wherein the downshifting sprocket teeth of the downshifting sprocket tooth type have a facet on a side facing a smaller sprocket, wherein the facet extends between the tip and the leading tooth flank.

10. The system according to claim 1, wherein the diameter of the protrusion is at least 3.3 mm and/or maximum 3.9 mm.

11. The system according to claim 1, wherein the protrusions define a generally flat or rounded inner guiding surface.

12. The system according to claim 11, wherein the area of the inner guiding surface is at least 0.9 mm.sup.2, and/or maximum 1.5 mm.sup.2.

13. The system according to claim 1, wherein the smallest distance between the protrusion and the edge of the outer link plate is at least 0.4 mm and/or maximum 0.8 mm.

14. The system according to claim 11, wherein the smallest distance between the guiding surface and an inner link plate is at least 1.6 nn and/or maximum 2.4 mm.

15. A bicycle with a drive chain system according to claim 1, wherein the bicycle comprises only a single chainring.

16. The system according to claim 5, wherein the taper is at an angle of at least 10° and/or maximum 12° to a plane parallel to the centerplane of the respective upshifting sprocket tooth.

17. The system according to claim 7, wherein the inclined surface is at an angle (β) of at least 120° and/or maximum 140°, to a plane parallel to the centerplane of the respective tooth.

18. The system according to claim 10, wherein the diameter of the protrusion is at least 3.5 mm and/or maximum 3.7 mm.

19. The system according to claim 12, wherein the area of the inner guiding surface is at least 1.1 mm.sup.2 and/or maximum 1.3 mm.sup.2.

20. The system according to claim 13, wherein the smallest distance between the protrusion and the edge of the outer link plate is at least 0.6 mm and/or maximum 0.7 mm.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0048] An embodiment of the drive chain system is described below with reference to the attached drawings.

[0049] FIG. 1 is a side view of a part of a chainring and an engaging portion of a chain.

[0050] FIG. 2 is a sectional view according to cutting line A-A in FIG. 1.

[0051] FIG. 3 is a side view of the part of the chainring of FIG. 1.

[0052] FIG. 4 is a sectional view according to cutting line B-B in FIG. 3.

[0053] FIG. 5 is a top view of the chain of FIG. 1.

[0054] FIG. 6 is a sectional view according to cutting line C-C in FIG. 5.

[0055] FIG. 7 is a perspective view of an outer link plate of the chain of FIG. 1.

[0056] FIG. 8 is a side view of an outer link plate of the chain of FIG. 1.

[0057] FIG. 9 is a sectional view according to cutting line D-D in FIG. 8.

[0058] FIG. 10 is a side view of a rear cassette with a portion of the chain of FIG. 1 up.

[0059] FIG. 11 is a top view of a rear cassette of FIG. 10.

[0060] FIG. 12 is an enlarged view of the Region D in FIG. 11.

[0061] FIG. 13 is a sectional view according to cutting line B-B in FIG. 12.

[0062] FIG. 14 is an enlarged view of the Region C in FIG. 13.

[0063] FIG. 15 is a sectional view of an upshifting sprocket tooth.

[0064] FIG. 16 is a sectional view of a downshifting sprocket tooth.

[0065] FIG. 17 is a sectional view of a neutral sprocket tooth.

[0066] FIG. 18 is a side view of a rear cassette with a portion of the chain of FIG. 1 down.

[0067] FIG. 19 is a top view of a rear cassette of FIG. 18.

[0068] FIG. 20 is an enlarged view of the Region A in FIG. 19.

DESCRIPTION OF EMBODIMENTS

[0069] FIG. 1 shows a side view of a portion of a drive chain 10 for a bicycle and a part of a chainring 12 engaging the chain.

[0070] The portion of the chain 10 comprises an alternating succession of inner chain links 14 and outer chain links 16. FIGS. 1 and 5 show inner chain links 14 connected by outer chain links 16. As can be seen in FIG. 5, the inner chain links 14 each have a pair of inner link plates 18 and the outer chain links 14 each have a pair of outer link plates 20. The inner link plates 18 comprise inner surfaces 22, facing each other and outer surfaces 24. The outer link plates 20 also comprise inner surfaces 26 facing each other and outer surfaces 28.

[0071] The inner surfaces 22 of a pair of inner link plates 18 can contact the lateral faces of two rollers 30 arranged in the end regions of the inner link plates 18. The inner surfaces 26 of the outer link plates 20 each contact the outer surfaces 24 of two adjacent inner link plates 18. The outer link plates 20, the inner link plates 18 and in particular the roller 30 are connected by means of a pin 32 so that the link plates can rotate around said pin 32.

[0072] FIG. 1 shows the part of a chainring 12 with three chainring teeth 34a, 34b, 34c, which engage with the chain 10. FIG. 1 shows that the chainring teeth 34a and 34c engage with inner chain links 14 and chainring tooth 34b engages with an outer chain link 16. Of course, the entire chainring 12 comprises further chainring teeth distributed about its circular periphery which are cut away in the representation of FIG. 1.

[0073] FIG. 2 shows a detailed sectional view of chainring tooth 34b engaging with a pair of outer link plates 20. The inner surfaces 26 of the opposite outer link plates 20 each comprise a protrusion 36 extending in the lateral (transversal) direction towards the chainring tooth 34b between the outer link plates 20 . In the shown embodiment, the thickness of the protrusion 36 measured from the inner surface of the outer link plate 20 where it contacts the outer surface of the inner link plate 18 may be equal to the thickness of the inner link plate 18. Consequently, the distance between two opposite and facing protrusions 36 on opposite outer link plates 20 may be equal to the distance between the opposite inner surfaces 22 of two inner link plates 18.

[0074] The protrusions 36 extend in longitudinal direction of the chain 10 in the area between the two inner link plates 18 that are located adjacent the respective outer link plate 20 and connected to it by means of pins 32. The outer surface 28 of the outer link plates 20 can comprise a trough-like recess 38 (also see FIG. 6) corresponding to the protrusion 36. The thickness of the outer link plates 20 can therefore be generally constant. The trough-like recess 38 and/or the corresponding protrusion 36 may extend over the major part of the height of the outer link plate 20.

[0075] The recess 38 can be formed by punching and may show no sharp edges lines. The transition between neighboring areas of the trough-like recess 36, such as the bottom 40 of the recess 38 and the side walls 42 of the recess 38 can be realized by radiuses. Also, the transition from the side walls 42 to the outer surface 28 of the outer link plate 20 adjacent to the recess 38 may have a radius.

[0076] The protrusion 36 may have a flat or rounded guiding surface 44 facing the chainring tooth 34b engaging the outer chain link 16. The guiding surface 44 can be generally located in the center of the protrusion 36 and may extend over about 25% of the height of the protrusion 36 and/or 25% of the length of the protrusion 36 in the longitudinal direction, which corresponds to the line connecting the axes of the two pins 32 connected to each chain link 14, 16. The shape of the guiding surface may vary from the shape shown in the drawings depending on the shape of the punch and the die used in the punching process.

[0077] The chainring teeth 34a, 34b and 34c can taper laterally towards their respective tip 50, as shown in the example. The chainring teeth 34a, 34b, 34c can comprise a lateral curvature 52. The lateral curvature can have a convex radius of at least 8 mm, particularly at least 10 mm, and/or maximum 14 mm, particularly maximum 12 mm.

[0078] It is possible that the chainring teeth 34a, 34b, 34c taper laterally in a section 54 between their respective tip 50 and a section 56 of the respective chainring tooth 34a, 34b, 34c with parallel lateral surfaces 64. In this case, the chainring teeth 34a, 34b, 34c can taper towards their tips 50 in a limited region near the tips 50 and therefore provide a fast increase in lateral guidance of the chain 10 when the tapering section 54 passes the space between the protrusions 36.

[0079] As shown in the embodiment, the distance 66 between the lateral surfaces 64 of the chainring teeth 34 can be at least 1.9 mm and/or maximum 2 mm in the section 56 of the respective chainring tooth 34 with parallel lateral surfaces.

[0080] The drive chain system can be configured in such manner that the protrusions 36 engage a chainring tooth 34 in its section with parallel lateral surfaces, when the chain is fully engaged to this chainring tooth 34. FIG. 1 and FIG. 2 show an outer chain link 16 link fully engaged to the chainring tooth 34b.

[0081] The section 56 with parallel lateral surfaces 64 may extend over a distance 48 of at least 0.5 mm, preferably at least 0.8 mm, towards the tip 50 of the chainring tooth 34b from the point of contact between the protrusion 36 and the chainring tooth 34b nearest to the tip 50 of the chainring tooth 34b, when the chain 10 is fully engaged to this chainring tooth 34b, as shown in FIG. 2.

[0082] The distance 70 the protrusion 36 protrudes from the outer link plate 20 towards a chainring tooth 34b can be at least 70%, preferably at least 90%, and/or maximum 130%, preferably maximum 110% of the distance the parallel lateral surfaces 64 extend towards the tip 50 of the chainring tooth 34b from the point of contact between the protrusion 36 and the chainring tooth 34b nearest to the tip 50 of the chainring tooth 34b, when the chain 10 is fully engaged to this chainring tooth 34b.

[0083] The tips 50 of the chainring teeth 34 can protrude from the chain links 14, 16 when the respective chain link 14, 16 is fully engaged with the respective chainring tooth 34a, 34b, 34c as shown in the embodiment.

[0084] The tips 50 of the chainring teeth 34 can be of a plateau-like shape with a length 75 of the plateau of at least 2.8 mm, in particular at least 3 mm, and/or maximum 3.5 mm, in particular maximum 3.2 mm.

[0085] The tips 50 of the chainring teeth 34 can be of a plateau-like shape with a width 76 of the plateau of at least 0.8 mm, in particular at least 0.9 mm, and/or maximum 1.2 mm, in particular maximum 1.1 mm.

[0086] The height 77 of the chainring teeth 34 can be at least 7.5 mm, in particular at least 8.5 mm, and/or maximum 9.5 mm, in particular maximum 8.5 mm.

[0087] The height 58 of the tapering section 54 can be at least 2.5 mm, in particular at least 3 mm, and/or maximum 4.5 mm, in particular maximum 4 mm.

[0088] The height 78 of the section 56 with parallel lateral surfaces 64 can be at least 3 mm, in particular at least 3.5 mm, and/or maximum 5 mm, in particular maximum 4.5 mm.

[0089] The clearance 80 between a protrusion 36 of an outer chain link 16 and one of the parallel lateral surfaces 64 of a chainring tooth 34b can be at least 0.1 mm, in particular at least 0.13 mm, and/or maximum 2.0 mm, in particular maximum 0.17 mm, when the opposite lateral surface 64 of the same chainring tooth 34b is in contact with the opposite protrusion 36 of the same outer chain link 16 and the outer chain link 16 is fully engaged with the chainring tooth 34b.

[0090] The circumference and/or diameter 72 of the protrusion 36 can be at least 60% and/or maximum 140% the circumference and/or diameter 62 of the eyes 60 of the outer link plate 20.

[0091] Preferably, the circumference and/or diameter 72 of the protrusion 36 is at least 90% and/or maximum 110% of the circumference and/or diameter 62 of the eyes 60 of the outer link plate 20.

[0092] In the shown embodiment, the diameter 62 of the eyes 60 of the outer chain link 20 may be at least 3 mm, preferably at least 3.4 mm, and/or maximum 4 mm, preferably maximum 3.6 mm.

[0093] The diameter 72 of the protrusion 36 may be at least 3.3 mm, preferably at least 3.5 mm, and/or maximum 3.9 mm, preferably maximum 3.7 mm. This sizes lead to a good guidance.

[0094] The protrusions 36 can define a generally flat or rounded inner guiding surface 44. The area of the inner guiding surface 44 may be at least 0.9 mm.sup.2, preferably at least 1.1 mm.sup.2, and/or maximum 1.5 mm.sup.2, preferably maximum 1.3 mm.sup.2.

[0095] As shown in the embodiment, the smallest distance 74 between the protrusion 36 and the edge 68 of the outer link plate 20 can be at least 0.4 mm, preferably at least 0.6 mm, and/or maximum 0.8 mm, preferably maximum 0.7 mm.

[0096] The width 82 of the inner link plates 18 can be at least 0.7 mm, in particular at least 0.75 mm, and/or maximum 1 mm, in particular maximum 0.95 mm.

[0097] The width 84 of the outer link plates 20 can be at least 0.7 mm, in particular at least 0.75 mm, and/or maximum 1 mm, in particular maximum 0.95 mm.

[0098] The distance 86 between the centers of the eyes 60 of the outer link plates 20 can be at least 11.7 mm, in particular at least 12.2 mm, and/or maximum 13.7 mm, in particular maximum 13.2 mm. Preferably the distance 86 between the centers of the eyes 60 of the outer link plates 20 is 12.7 mm.

[0099] The distance 88 between the two rollers 30 of a chain link 14, 16 can be at least 4 mm, in particular at least 4.5 mm, and/or maximum 6 mm, in particular maximum 5.5 mm.

[0100] As shown in the embodiment, the smallest distance 90 between the protrusion 36 and a roller 30 can be at least 0.2 mm, preferably at least 0.75 mm, and/or maximum 0.9 mm, preferably maximum 0.85 mm.

[0101] As shown in the embodiment, the smallest distance 92 between the center of the protrusion 36 and an inner link plate 20 can be at least 2.1 mm, preferably at least 2.2 mm, and/or maximum 2.9 mm, preferably maximum 2.7 mm.

[0102] As shown in the embodiment, the smallest distance 94 between the guiding surface 44 and an inner link plate 20 can be at least 1.6 mm, preferably at least 1.8 mm, and/or maximum 2.4 mm, preferably maximum 2.2 mm.

[0103] As shown in the embodiment, the diameter 96 of the rollers 30 can be at least 7 mm, preferably at least 7.5 mm, and/or maximum 8.5 mm, preferably maximum 8 mm.

[0104] As shown in the embodiment, the width of the rollers 30 can be at least 1.7 mm, preferably at least 1.9 mm, and/or maximum 2.5 mm, preferably maximum 2.3 mm.

[0105] The cassette 100 comprises sprocket teeth of different tooth types, the sprocket teeth of at least one sprocket tooth type having a tip laterally offset from the centerplane 102 of the respective sprocket tooth.

[0106] At least one sprocket tooth type can be an upshifting sprocket tooth type supporting shifting to a larger sprocket, the upshifting sprocket teeth 104 of this upshifting sprocket tooth type having a tip 106 laterally offset towards a smaller sprocket. Such an upshifting operation is shown in FIGS. 10 to 12.

[0107] As one can see especially in FIG. 12, with these upshifting sprocket teeth, the tip 106 offset towards the smaller sprocket comes into contact more easily with a chain link moved from the rear derailleur to the larger sprocket during the shifting process. In combination with the protrusions 36 on the outer link plates 20, there is also the advantage that the laterally offset tip 106 can engage the protrusion 36 after initial contact with the outer chain link 16 to move the chain 10 further in lateral towards the larger sprocket.

[0108] The cassette 100 particularly comprises upshifting sprocket teeth 104 of at least two different upshifting sprocket tooth types supporting shifting to a larger sprocket, wherein the distance by which the tips 106 of the at least two upshifting sprocket tooth types are offset towards the smaller sprocket being different between the at least two upshifting sprocket tooth types. Examples for different upshifting sprocket teeth 104 can be found especially comparing the different upshifting sprocket tooth types shown in FIGS. 14 and 15.

[0109] The upshifting sprocket teeth 104 of at least one upshifting sprocket tooth type may have on their side facing a smaller sprocket a taper of the tooth towards the tip 106 at an angle α. Such a taper is shown in especially in FIG. 14.

[0110] The teeth of at least one upshifting sprocket tooth type may have an inclined surface 108 at an angle β between their side facing a larger sprocket and the tip (106). Such an inclined surface 108 is shown especially in FIGS. 12, 14 and 15.

[0111] At least one sprocket tooth type may be a downshifting sprocket tooth type supporting shifting to a smaller sprocket, the downshifting sprocket teeth 110 of this tooth type having a tip 112 laterally offset towards a larger sprocket. This is shown especially in FIG. 16.

[0112] The downshifting sprocket teeth 110 of the downshifting sprocket tooth type can have a facet 114 on their side facing a smaller sprocket. The facet 114 can extend between the tip 112 and the leading tooth flank. Such a facet 114 may, in particular during the shifting operation to a smaller sprocket, enable the downshifting sprocket tooth 110 to slide in a controlled manner beside a chain link 14, 16 and guide the chain link 14, 16 in direction of its lateral target position on the smaller sprocket. This is shown best in FIG. 20.

[0113] As one can see in FIG. 20, there can also be a beneficial effect in combination with the protrusions 36 and the inclined surfaces 108 of the upshifting sprocket teeth 104 during the downshifting operation. The inclined surface 108 can engage with a protrusion 36 and support a chain link lateral position located between the sprockets involved in the downshifting operation.

[0114] As shown in FIG. 17, at least one sprocket tooth type can be a neutral sprocket tooth type with neutral sprocket teeth 116 having no laterally offset tips.

REFERENCE NUMERALS

[0115] 10 chain

[0116] 12 chainring

[0117] 14 inner chain link

[0118] 16 outer chain link

[0119] 18 inner link plate

[0120] 20 outer link plate

[0121] 22 inner surface of inner link plate

[0122] 24 outer surface of inner link plate

[0123] 26 inner surface of outer link plate

[0124] 28 outer surface of outer link plate

[0125] 30 roller

[0126] 32 pin

[0127] 34a, 34b, 34c chainring tooth

[0128] 36 protrusion

[0129] 38 recess

[0130] 40 bottom

[0131] 42 side wall

[0132] 44 guiding surface

[0133] 46 distance

[0134] 48 distance

[0135] 50 tip

[0136] 52 curvature

[0137] 54 tapering section

[0138] 58 height tapering section

[0139] 60 eye

[0140] 62 diameter

[0141] 64 lateral surface

[0142] 66 distance

[0143] 68 edge

[0144] 70 distance

[0145] 72 diameter

[0146] 74 distance

[0147] 75 length tip

[0148] 76 width tip

[0149] 77 height chainring teeth

[0150] 78 height

[0151] 80 clearance

[0152] 82 width inner link plate

[0153] 84 width outer link plate

[0154] 86 distance

[0155] 88 distance

[0156] 90 distance

[0157] 92 distance

[0158] 94 distance

[0159] 96 diameter

[0160] 98 width

[0161] 100 cassette

[0162] 102 centerplane

[0163] 104 upshifting sprocket tooth

[0164] 106 tip

[0165] 108 inclined surface

[0166] 110 downshifting sprocket tooth

[0167] 112 tip

[0168] 114 facet

[0169] 116 neutral sprocket tooth

[0170] 118 rotation direction while driving

[0171] α angle (taper)

[0172] β angle (inclined surface)