GB2302846A

GB2302846A - Bicycle hub

Info

Publication number: GB2302846A
Application number: GB9612643A
Authority: GB
Inventors: Souta Hamada
Original assignee: Shimano Inc
Current assignee: Shimano Inc
Priority date: 1995-06-30
Filing date: 1996-06-17
Publication date: 1997-02-05
Anticipated expiration: 2016-06-17
Also published as: GB2302846B; DE19626072A1; JPH0971102A; JP3080214B2; DE19626072C2; GB9612643D0

Description

1 Bicycle Hub 2 3 4 6 8 9 10 11 12 13 14 16 17 18 19 20 21 22 23 24 25 1

2302846 The present invention relates to a bicycle hub. It relates especially to a bicycle hub with a construction such that the spokes and the sprocket do not interfere during the assembly of the wheel even if hooking holes, which each consist of three connected holes formed in the hub flanges and through which the spokes are inserted, are not used and only straight holes, which each consist of a single hole, are used.

A bicycle hub must be able to withstand the static and dynamic loads to which the wheel is subjected in use, and must allow the wheel to rotate smoothly and comfortably. Spokes are linear components that radially connect the central hub to the rim that runs around the outside of the wheel. The spokes comprise a spoke wire, at one end of which is formed a hook that fits into the spoke hole of the hub flange and at the other end of which is formed a threaded portion, and a nipple that passes through the spoke hole of the rim, fits over the threaded portion of the spoke wire, and adjusts the tightness of and fixes the spoke wire. During assembly or replacement of a spoke there is a potential difficulty in inserting the spoke into the 2 2 3 4 5 6 7 11 12 13 14 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 associated hole in the hub flange because the sprocket associated with, for example, the free wheel mechanism of the hub is generally positioned so as to make access to the hole difficult.

Spoke holes into which the spokes are inserted and supported are made in the flanges of the hub shell.

8 There are two types of spoke hole: a straight hole (round hole) consisting of a singe hole, and a hooking hole consisting of three connected holes. An advantage of hooking holes is that they allow the spokes to be replaced in an assembled state, without the free wheel having to be removed. However, when the bicycle is ridden harshly, is in a collision, or the like, the rim can distort and cause the hooked portion of a spoke to come out of its hooking hole.

Another problem with hooking holes is that the hooked portion of a spoke can come out of the central hole during assembly after the spoke has been inserted, so this central hole is sometimes filled in. Upon completion of the assembly, this filling must be taken out. It is therefore preferable to avoid the use of hooking holes and the associated problems as much as possible.

A desirable hub construction would be one that avoids the use of hooking holes and still allows the spokes to be replaced in an assembled state, without the free wheel having to be removed.

An object of the present invention is to offer a bicycle hub in which interference between the spokes and the sprocket during the assembly of the wheel is eliminated or reduced even when straight holes, each comprising a single hole provided in the hub shell, are 3 1 used.

2 3 4 6 7 8 9 10 12 13 14 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 According to a first aspect of the present invention there is provided a bicycle hub with a combined hub cog, for use as the hub of a bicycle wheel, said bicycle hub comprising: a hub axle that passes through the center of the hub; a hub shell comprising [i] first and second flanges that are rotatably supported by bearings around the outside of the hub axle, are arranged substantially parallel, and have substantially circular spoke straight holes, and Cii) a pipe member that connects the first and second flanges; and a sprocket, on the second flange side of the hub and adjacent to the second flange, said sprocket being part of a cog arrangement adapted to transmit rotational force from a drive chain in only one direction to the hub shell; characterized in that the sprocket is provided with spoke insertion openings adapted to facilitate access to portions of the second flange to which access would otherwise be obstructed by the sprocket, so as to allow spokes to be inserted into the spoke straight holes of the second flange from the sprocket side of the second flange without the sprocket having to be removed.

Preferably, the spoke insertion openings are formed such that the spokes do not interfere with the sprocket.

Preferably, the width of the spoke insertion opening is greater than the diameter of the spokes.

Preferably, said openings are in the form of notches.

Preferably, said bicycle hub includes only a single sprocket.

4 1 2 3 4 6 7 8 9 10 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Preferably, the sprocket includes a number of outwardly extending teeth and has contoured regions defining gaps between the teeth, said contoured regions having tooth bottoms corresponding to the radially innermost points on the respective contours, and the sprocket is provided with one or more spoke insertion notches each formed in a respective tooth bottom region of a gap such that the spoke insertion notches extend radially inwardly to a greater degree than the gaps which do not include spoke insertion notches.

Preferably, the radially innermost regions of the spoke insertion notches are arcuate in form.

Preferably, the portion of the sprocket periphery defining each spoke insertion notch is substantially continuous and is also substantially continuous with the portion of the sprocket periphery which defines at least some part of at least one adjoining sprocket tooth.

Preferably, the radially innermost part of the spoke insertion opening is not further from the centre of the sprocket than the innermost point on the sprocket which can be intersected by a line passing through a point on the outer peripheral edge of the first flange and through a spoke insertion hole of the second flange.

According to a second aspect of the present invention there is provided a sprocket for a bicycle, wherein said sprocket includes a number of outwardly extending teeth and has contoured regions defining gaps between the teeth, said contoured regions having tooth bottoms corresponding to the radially innermost points on the respective contours, characterized in that the sprocket is provided with one or more spoke insertion notches 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 each formed in a respective tooth bottom region of a gap such that the spoke insertion notches extend radially inwardly to a greater degree than the gaps which do not include spoke insertion notches.

Embodiments of the present invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a front view of a bicycle hub that is one embodiment of the present invention; Figure 2 is a right side view of Figure 1; Figure 3 is an enlarged view of the tooth profile of the sprocket; and Figure 4 is a partial cross section of when a spoke is inserted into the flange from the outside.

Figure 1 is a front view of a bicycle hub that is an embodiment of the present invention. In this embodiment, the present invention is applied to a component known as a "unit hub with a combined hub cog", generally designated 1. A hub axle 2, which is threaded at both ends, is positioned to pass through the centre of the unit hub 1. A pipe 3 is positioned at a distance around the outside of the centre portion of the hub axle 2.

Flanges 4 and 5 are integrally fixed at the ends of the pipe 3, and the pipe 3 and the flanges 4 and 5 make up a hub shell 6. The interior of the hub shell 6 in this embodiment has a standardized, conventional construction, and the description thereof will be

6 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 omitted here. A combined hub cog 7 is positioned on the lateral surface of the flange 5. A cylinder 8 is integrally moulded to the combined hub cog 7. The interior of the cylinder 8 contains conventional bearings (steel balls), a free wheel mechanism, and so on.

The function of the free wheel mechanism is to transmit the rotational force of the chain in only one direction, and this mechanism is equipped with a ratchet mechanism or other one-way clutch. These mechanisms used in this embodiment are conventional, standardized parts, and the description of their construction will be omitted.

The combined hub cog 7 is fixed by a threaded cover 9. The hub shell 6 is rotatably supported on the hub axle 2 by the steel balls (not shown) that make up the bearing. The steel balls are pressed and supported by cones 10 and 11. The cones 10 and 11 are locked to the hub axle 2 by lock nuts 12 and 13. Straight holes (round holes) 14 and 15 are made at isometric positions around the periphery of the flanges 4 and 5.

Each of the straight holes (round holes) 14 and 15 consists of a single hole which extends all the way through the respective flange and is chamfered at both ends. In this embodiment, there are 18 of the straight holes (round holes) 14 and 15 positioned at isometric locations around the periphery of each of the flanges 4 and 5. The shape of the sprocket 16 of the combined hub cog 7 is different from that of a conventional sprocket in order to facilitate access to the flange 5.

Figure 2 is a right side view of the embodiment of Figure 1 showing, in particular, the sprocket 16.

7 1 Figure 3 is an enlarged view of the tooth profile of 2 the sprocket 16. In this embodiment, the sprocket 16 3 has fourteen teeth. Spoke insertion notches 20 are 4 formed by extension of the gap between two adjacent 5 teeth, inwardly, towards the centre of the sprocket 16. 6 The radially innermost point of the normal gap between 7 two teeth is referred to as a tooth bottom 21. The 8 radially innermost point of the spoke insertion notch 9 is referred to as the notch tooth bottom. The spoke 10 insertion notches 20 are, in this embodiment, formed at 11 intervals of 120' angles. The regions of the tooth 12 bottoms 21 where no spoke insertion notches are formed 13 have curved surfaces 22 formed at a radius of rj. The 14 curved surfaces 22 are tangent to a tooth bottom circle 15 having radius R2. Tooth faces 23 with a radius of r2 16 are formed as a continuation of these curved surfaces 17 22, and make up addenda 24. These addenda 24 are 18 tangent to an addendum circle having radius R,. 19 20 In the spoke insertion notches 20, flat surfaces 26 are 21 formed as a continuation of the tooth faces 23, and the 22 borders thereof form intersecting lines 25. Arcuate 23 surfaces 27 with a radius r3 are formed as a 24 continuation of the flat surfaces 26, and the flat 25 surfaces 26 form tangential planes with the arcuate 26 surfaces 27. The arcuate surfaces 27 are tangent to a 27 spoke insertion notch bottom circle having radius R3. 28 Similarly, the flat surfaces 26, the intersecting lines 29 25, and the tooth faces 23 are formed as a continuation 30 of the arcuate surfaces 27. The flat surfaces 26 form 31 an angle 01 with the radial direction. 32 33 This means that the spoke insertion notches 20 at the 34 three places in the sprocket 16 are cut out by the 35 difference between the tooth bottom circle R2 and the 36 notch tooth bottom circle R3 in order to allow access to 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 spoke holes 14, 15. Unless the width of the spoke insertion notches 20 is greater than the diameter of the widest part of hooked portion 31 (see Figure 4) of the spoke 30, then the hooked portion 31 will not be able to pass through when the assembly method discussed below is adopted.

The method for assembling the spokes 30 to the combined hub cog-equipped unit hub 1 will now be described for the embodiment of Figures 1 to 4. Figure 4 is a partial cross section showing the situation when a spoke 30 has been inserted into the flange 5 from the outside. Many different methods are known for putting together a tangent spoke wheel, but usually the spokes 30 are alternately inserted with the threaded portion 32 first from the left and right (both sides of the plate thickness) of the flange 5, and the hooked portions 31 are retained in the straight holes 14.

Since there is no sprocket on the side of the unit associated with the flange 4, passing the spokes 30 from the left and right sides of the flange 4 does not interfere with anything, and poses no problem. However, when the spokes 30 are to be inserted from the right side (in the figure) of the flange 5, if they are to be passed through the tooth bottom 21 of the sprocket 16 and inserted into the straight holes 14 of the flange 5, the tooth bottom 21 interferes and the spokes cannot be inserted.

Specifically, as shown in Figure 4, when the tip of the spoke 30 is tangent to the straight hole 14 and the peripheral surface of the flange 4, the angle formed by the centre line of the hub axle 2 and the centre line of the spoke 30 is 0. In other words, since the diameter d of the spoke 30 is different to and smaller 9 4 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 than the diameter of the straight hole 14, there is 2 some play, and in actual practice the outer peripheral surface of the spoke 30 and the straight hole 14 are tangent at the position of the maximum radius R5 from the above-mentioned centre of the hub axle 2, and at the inner peripheral surface of the straight hole 14.

Therefore, the minimum value of 0 (which determines the minimum necessary depth of the spoke insertion notches 20 in this embodiment) is determined by the relation between the gap H, between the flange 4 and the flange 5, the radius R4 Of the outer periphery of the f lange 4, and the radius R5 of the circle of straight holes 14 of the flange 5. Also, it can be seen that if we let the gap between the f lange 5 and the sprocket 16 be H,, then if the radius R3 of the spoke insertion notch tooth bottom circle is in an approximate relation of [ Mathematical Formula 1] R3:5 R4 - (H, + H2) 9 tanO and Mathematical Formula 2 tanO = (R4 - (R.5 - d))/H, (where R5 is the maximum radius of the inner peripheral surface of the straight hole 14 of the flange 5, H, is the gap between the flange 4 and the flange 5, and H2 'S the gap in the axial direction of the hub axle between the flange 5 and the sprocket 16), the spoke 30 will not interfere with the sprocket 16. Clearly smaller values of R3 will not cause the spoke 30 to interfere with the sprocket 16, but larger values of R3 might cause such interference to occur.

The above relational formulas apply to a bicycle hub with the structure of the illustrated embodiment, and 2 3 4 5 6 7 8 11 13 14 15 16 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 are not necessarily applicable to a bicycle hub with a different structure. Also, the minimum value for the diameter d of the spoke 30 currently being used in practical applications is 1.6 mm. Therefore, the spoke insertion notches 20 should be formed with a width at least large enough for a spoke 30 with a diameter of 1.6 mm or more to pass through said notches. Specifically, the width of the spoke insertion notches 20 should be at least 1.6 mm (the diameter of the spoke 30) corresponding to the radius r3 being at least 0.8 mm, and preferably the width of the notches should be formed larger than the diameter of the widest part of the hooked portion 31 of the spoke 30.

As discussed in detail above, with correct rotational positioning of the sprocket 16, and thus the spoke insertion notches 20, the spoke 30 can be passed through one of the spoke insertion notches 20 and inserted into the straight hole 14 of the flange 5 without interfering with the sprocket 16.

In the illustrated embodiment of the present invention, the spokes 30 were assembled without being bent. However, since the spokes 30 are made from steel, stainless steel, or another such elastic material, they can also be assembled by being inserted into the straight holes 14 while being bent within their range of elastic deformation, as long as they are not bent so much that they undergo plastic deformation. In this case, the radius R3 of the tooth bottom circle of the above-mentioned spoke insertion notches 20 may be larger than in the above example but should still be smaller than the radius R2 of the tooth bottom circle of the sprocket 16.

In this case, the spokes 30 will be more difficult to 11 1 2 3 4 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 insert into the straight holes 14. However, since the spokes only need to be bent by being subjected to a reduced amount of elastic deformation, the assembly is still easier than if no spoke insertion notches 20 were provided.

The spoke insertion notches 20 in the above embodiments were provided in three locations spaced equally around the sprocket 16, but they may be provided to a minimum of one place, as can be inferred from the description of the above embodiments. Also, the above embodiments were applied to the combined hub cog of a unit hub, but can also be applied to other known types of hub, such as a type used for a multiple sprocket hub cog.

As discussed in detail above, the described embodiments of bicycle hub in accordance with the present invention involves the formation of spoke insertion notches in the sprocket, so it has the benefit of allowing spoke assembly in a state in which the band drum, free wheel, and other such interfering parts are still assembled, i.e. have not been removed, and allows the spokes to be removed without being bent.

The above described embodiments illustrate preserve embodiments of the invention but it will be appreciated that many variations in the form of the described components, and in particular the sprocket, may be utilised without departing from the scope of the invention.

12

Claims

1 CLAIMS

2 3 1 A bicycle hub with a combined hub cog, for use as 4 the hub of a bicycle wheel, said bicycle hub comprising:

6 a hub axle that passes through the center of 7 the hub; 8 a hub shell comprising [i] first and second 9 flanges that are rotatably supported by bearings around the outside of the hub axle, are arranged 11 substantially parallel, and have substantially 12 circular spoke straight holes, and [ii] a pipe 13 member that connects the first and second flanges; 14 and a sprocket, on the second flange side of the 16 hub and adjacent to the second flange, said 17 sprocket being part of a cog arrangement adapted 18 to transmit rotational force from a drive chain in 19 only one direction to the hub shell; characterized in that the sprocket is 21 provided with spoke insertion openings adapted to 22 facilitate access to portions of the second flange 23 to which access would otherwise be obstructed by 24 the sprocket, so as to allow spokes to be inserted into the spoke straight holes of the second flange 26 from the sprocket side of the second flange 27 without the sprocket having to be removed.

28 29 2 A bicycle hub as defined in Claim 1, wherein the spoke insertion openings are formed such that the 31 spokes do not interfere with the sprocket.

32 33 3 A bicycle hub as defined in either of Claims 1 or 34 2, wherein the width of the spoke insertion opening is greater than the diameter of the 36 spokes.

13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 26 27 28 29 30 31 32 33 34 35 36 4 6 7 8 9 A bicycle hub as claimed in any preceding claim, wherein said openings are in the form of notches.

A bicycle hub as defined in any preceding claim, wherein said bicycle hub includes only a single sprocket.

A bicycle hub as defined in any preceding claim, wherein the sprocket includes a number of outwardly extending teeth and has contoured regions defining gaps between the teeth, said contoured regions having tooth bottoms corresponding to the radially innermost points on the respective contours, characterized in that the sprocket is provided with one or more spoke insertion notches each formed in a respective tooth bottom region of a gap such that the spoke insertion notches extend radially inwardly to a greater degree than the gaps which do not include spoke insertion notches.

A bicycle hub as claimed in claim 6 wherein the radially innermost regions of the spoke insertion notches are arcuate in form.

A bicycle hub as claimed in either of claims 6 or 7 wherein the portion of the sprocket periphery defining each spoke insertion notch is substantially continuous and is also substantially continuous with the portion of the sprocket periphery which defines at least some part of at least one adjoining sprocket tooth.

A bicycle hub as claimed in any preceding claim wherein the radially innermost part of the spoke insertion opening is not further from the centre 14 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 12 of the sprocket than the innermost point on the sprocket which can be intersected by a line passing through a point on the outer peripheral edge of the first flange and through a spoke insertion hole of the second flange.

A sprocket for a bicycle, wherein said sprocket includes a number of outwardly extending teeth and has contoured regions defining gaps between the teeth, said contoured regions having tooth bottoms corresponding to the radially innermost points on the respective contours, characterized in that the sprocket is provided with one or more spoke insertion notches each formed in a respective tooth bottom region of a gap such that the spoke insertion notches extend radially inwardly to a greater degree than the gaps which do not include spoke insertion notches.

A bicycle hub substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

A sprocket substantially as hereinbefore described with reference to and as shown in the accompanying drawings.