Sprocket-carrying body and sub-assembly of sprocket-carrying body and cogset for a bicycle rear wheel

Abstract

A cogset with a plurality of sprockets has a subset of the sprockets connected together in a monolithic subset that is mounted directly in engagement with a coupling profile on the radially peripheral surface of a sprocket in the monolithic subset. The direct shape coupling between the sprocket of the monolithic subset and the sprocket-carrying body makes it possible to have very high solidity and rigidity of coupling to ensure the maximum precision of actuation of the gearshift that uses the sub-assembly.

Claims

1. A cogset for a bicycle rear wheel, the cogset comprising a plurality of adjacent sprockets adapted for being mounted coaxially on a sprocket-carrying body, the plurality of adjacent sprockets numbering between 12 and 14 sprockets where a first sprocket has a minimum number of teeth and a last sprocket has a maximum number of teeth, wherein “n” sprockets from the plurality of sprockets are fixedly connected together in a monolithic set, where the range of “n” is 6≥n≥3, and the monolithic set is adapted for direct engagement on a coupling profile formed on a radially peripheral surface of a sprocket-carrying body through a coupling profile formed on a radially inner surface of at least the largest sprocket of the monolithic set.

2. The cogset according to claim 1, wherein the first sprocket in the monolithic set has 10 teeth.

3. The cogset according to claim 1, wherein the first sprocket in the monolithic set has 9 teeth.

4. The cogset according to claim 1, wherein the first sprocket in the monolithic set has 8 teeth.

5. The cogset according to claim 1, wherein n=3.

6. The cogset according to claim 1, wherein n=4.

7. The cogset according to claim 1, wherein n=5 and the coupling profile between the monolithic set and the sprocket-carrying body is formed on a radially inner surface of the two largest sprockets of the monolithic set.

8. The cogset according to claim 1, wherein n=6 and the coupling profile between the monolithic set and the sprocket-carrying body is formed on a radially inner surface of the two largest sprockets of the monolithic set.

9. A sub-assembly for a bicycle rear wheel, the sub-assembly comprising a sprocket-carrying body and a cogset mounted coaxially on the sprocket-carrying body, wherein the cogset comprises a plurality of 12 to 14 axially adjacent sprockets between a first sprocket having a minimum number of teeth and a last sprocket having a maximum number of teeth, wherein the sprockets are mounted coaxially on a sprocket-carrying body, wherein “n” sprockets of the plurality of axially adjacent sprockets, where “n” is 6≥n≥3, are fixedly connected in a monolithic set, and wherein the monolithic set is directly engaged on a coupling profile formed on a radially peripheral surface of the sprocket-carrying body through a coupling profile of the monolithic set.

10. The sub-assembly according to claim 9, wherein the monolithic set comprises an axial abutment surface in abutting engagement against a corresponding outer axial abutment surface of the sprocket-carrying body.

11. The sub-assembly according to claim 10, wherein the sprocket-carrying body comprises a radially inner threaded portion.

12. The sub-assembly according to claim 9, further comprising a ring nut with a threaded portion screwed into a radially inner threaded portion of the sprocket-carrying body.

13. The sub-assembly according to claim 10, further comprising a ring nut with a threaded portion screwed into a radially inner threaded portion of the sprocket-carrying body.

14. The sub-assembly according to claim 11, further comprising a ring nut with a threaded portion screwed into the radially inner threaded portion of the sprocket-carrying body.

15. A cogset for a bicycle rear wheel, the cogset comprising at least 12 and no more than 14 sprockets adapted for being mounted coaxially on a sprocket-carrying body, where a first sprocket has a minimum number of teeth and a last sprocket has a maximum number of teeth, and “n” sprockets are fixed together in a monolithic set that includes the first sprocket, where “n” is in the range of 6≥n≥3, and the monolithic set is adapted for direct engagement on a coupling profile formed on a radially peripheral surface of a sprocket-carrying body through a coupling profile formed on a radially inner surface of at least a largest sprocket in the monolithic set.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The features and advantages of the invention will become clearer from the following description of a preferred embodiment thereof, made with reference to the attached drawings. In such drawings:

(2) FIG. 1 is a perspective view of a hub of a bicycle rear wheel with a sub-assembly and a cogset according to the invention;

(3) FIG. 2 is an axial section view of the hub of FIG. 1;

(4) FIG. 3 is an enlarged section view of part of the hub of FIG. 2;

(5) FIG. 4 is a perspective view of the sub-assembly of FIG. 1, with parts removed to better show the sprocket-carrying body and the monolithic set of the smallest sprockets;

(6) FIG. 5 is a perspective view of only the monolithic set shown in FIG. 4;

(7) FIGS. 6 and 7 are perspective views from different angles of a variant of the monolithic set;

(8) FIG. 8 is a section view of the monolithic set of FIGS. 6 and 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) According to a first aspect of the invention, a cogset comprises a plurality of axially adjacent sprockets between a first sprocket having minimum number of teeth and a last sprocket having maximum number of teeth, wherein the first n sprockets with 6≥n≥3 are fixedly connected to one another so as to form a monolithic set, and in which the monolithic set is adapted for being directly in shape engagement on a coupling profile formed on the radially peripheral surface of the sprocket-carrying body through a coupling profile formed on the radially inner surface of at least the largest sprocket of the monolithic set.

(10) Having at least three sprockets grouped in the monolithic set makes it possible to have a sprocket with 11 teeth suitable for direct engagement on the sprocket-carrying body and two or more smaller sprockets cantilevered; therefore, the first sprocket may have as few as 9 teeth (or less), without it being necessary to accept a difference greater than 1 between the number of teeth of the adjacent smallest sprockets. Moreover, the fact that a direct shape coupling is provided between the largest sprocket of the monolithic set and the sprocket-carrying body, and the fact that this direct coupling is made between the radially peripheral surface of the sprocket-carrying body and the radially inner surface of the largest sprocket (or of the largest sprockets) of the monolithic set, makes it possible to have very high solidity and rigidity of coupling, so as to ensure the maximum precision of actuation of the gearshift that uses the sub-assembly, comparable to the precision of a gearshift in which the sprockets of the cogset are all individually and directly mounted so as to rotate as a unit on the sprocket-carrying body.

(11) Preferably, the first sprocket has 10, 9 or even 8 teeth. It is thus possible to achieve very long gear ratios of the gearshift.

(12) Preferably, the number n of sprockets of the monolithic set is equal to 3, 4, 5 or even 6. The greater this number n, the greater the flexibility in the selection of the number of teeth of each of them and thus of the gear ratios.

(13) In the case in which there are 5 sprockets of the monolithic set, the coupling profile between the monolithic set and the sprocket-carrying body is preferably formed on the radially inner surface of the two largest sprockets of the monolithic set.

(14) In the case in which there are 6 sprockets of the monolithic set, the coupling profile between the monolithic set and the sprocket-carrying body is preferably formed on the radially inner surface of the three largest sprockets of the monolithic set.

(15) These features make it possible to keep the solidity and the rigidity of the coupling between the sprockets of the monolithic set and the sprocket-carrying body high, even when the number n of sprockets of the monolithic set is relatively high.

(16) Preferably, the cogset comprises 12, 13 or even 14 sprockets. The invention is indeed particularly interesting when the number of sprockets is high, greater than 11.

(17) According to a second aspect of the invention, a sub-assembly comprises a sprocket-carrying body and a cogset mounted coaxially on the sprocket-carrying body, wherein the cogset comprises a plurality of axially adjacent sprockets between a first sprocket having minimum number of teeth and a last sprocket having maximum number of teeth, wherein the first n sprockets with 6≥n≥3 are fixedly connected to one another so as to form a monolithic set, and wherein the monolithic set is directly in shape engagement on a coupling profile formed on the radially peripheral surface of the sprocket-carrying body through a coupling profile formed on the radially inner surface of at least the largest sprocket of the monolithic set.

(18) Preferably, the monolithic set comprises an axial abutment surface in abutting engagement against a corresponding outer axial abutment surface of the sprocket-carrying body. This allows a precise and stable axial positioning of the monolithic set with respect to the sprocket-carrying body.

(19) Preferably, the sprocket-carrying body comprises a radially inner threaded portion.

(20) Preferably, the sub-assembly further comprises a ring nut with a threaded portion screwed into the radially inner threaded portion of the sprocket-carrying body.

(21) The attachment through the ring nut ensures a stable and precise positioning in the axial direction of the entire cogset on the sprocket-carrying body.

(22) With reference now to the drawings, FIG. 1 represents a hub 10 of a hub assembly 1 of a bicycle rear wheel (not shown), mounted coaxially on a pin 11, by means of bearings 12; the hub 10 is thus free to rotate on the pin 11, whereas the latter is intended to be mounted fixed on the frame of the bicycle.

(23) The hub 10 is coupled with a sprocket-carrying body 14, through a free wheel mechanism (not highlighted) that ensures that the hub 10 is set in rotation by the sprocket-carrying body 14 only in the direction that determines forward motion of the bicycle, not in the opposite direction. The sprocket-carrying body 14 has an approximately tubular shape and is mounted free on the pin 11, by means of bearings 15. The sprocket-carrying body 14 is provided on its radially peripheral surface with a coupling profile formed by grooves 16 arranged in the axial direction. Moreover, the sprocket-carrying body 14 is provided close to its axially inner end with an end stop 18, in the form of teeth projecting in the radial direction from the sprocket-carrying body 14; alternatively instead of the teeth, as end stop 18 it is possible to provide a flange, extending along the entire circumference of the sprocket-carrying body 14.

(24) The sprocket-carrying body 14 has a substantially annular axial abutment surface 17 at the outer axial end thereof.

(25) A cogset 20 is mounted on the sprocket-carrying body 14, with formation of a sub-assembly 2. The shown cogset 20 comprises 12 sprockets organized from the largest to the smallest as follows: the three largest sprockets 21a, 21b, 21c are made fixedly connected to one another to form a monolithic set (or triplet) 21; the next three sprockets 22a, 22b, 22c are made fixedly connected to one another to form a monolithic set (or triplet) 22; the next three sprockets 23, 24, 25 are independent from one another; the three smallest sprockets 26a, 26b, 26c are made fixedly connected to one another to form a monolithic set (or triplet) 26. These elements are mounted peripherally on the sprocket-carrying body 14, with the monolithic set 21 rested axially at the end stop 18, the monolithic set 22 rested axially at the monolithic set 21, the sprocket 23 rested axially at the monolithic set 22, the sprocket 24 rested axially at the sprocket 23, the sprocket 25 rested axially at the sprocket 24, the monolithic set 26 rested axially at the sprocket 25.

(26) The monolithic sets 21, 22 and the sprockets 23-25 are slotted onto the sprocket-carrying body 14, constrained in rotation to the sprocket-carrying body 14 but substantially free in the axial direction; the constraint in rotation is ensured in a per se conventional manner by the grooves 16 that engage with corresponding projections (not visible in the figures) on the radially inner surface of the monolithic sets 21, 22 and of the sprockets 23-25.

(27) In the sub-assembly 2 formed by the sprocket-carrying body 14 and the cogset 20, as stated, 12 sprockets are mounted, single or grouped in monolithic sets. In particular, there is a very small sprocket, the sprocket 26c, which has a number of teeth so low as not to be able to be mounted on the sprocket-carrying body 14 without the provision of having grouped it in the monolithic set 26. Indeed, if this small sprocket were single, it would be too small to be able to be slotted on the sprocket-carrying body 14; the monolithic set 26, on the other hand, can have an inner axial portion at the sprocket 26a (which has 12 teeth) of dimensions such as to be able to engage on the sprocket-carrying body 14.

(28) The monolithic set 26, visible particularly in FIGS. 4-8, comprises—at the largest sprocket 26a—a series of projections 32 facing radially inwards, which as a whole constitute an inner shape coupling profile formed on the radially inner surface of the sprocket 26a. This coupling profile formed by the projections 32 has a shape corresponding to that of the coupling profile formed by the grooves 16 on the radially peripheral surface of the sprocket-carrying body 14. In mounting, the monolithic set 26 is thus partially slotted onto the sprocket-carrying body 14, with the projections 32 that engage in the grooves 16, whereas the smallest sprockets 26b and 26c of the monolithic set 26 remain axially cantilevered. This provision, made on the radially peripheral surface of the sprocket-carrying body 14, ensures that the entire monolithic set 26 (and therefore all of its sprockets 26a, 26b and 26c) is made to rotate as a unit with the sprocket-carrying body 14 in a stable and secure manner; any uncertainty of coupling (i.e. any possibility of angular micro-displacements of the monolithic set 26 with respect to the sprocket-carrying body 14), which would make the operation of a gearshift using the sub-assembly 2 imprecise, is thus ruled out.

(29) The monolithic set 26 has a substantially annular axial abutment surface 27, at the inner shape coupling profile formed by the projections 32. The abutment surface 27 goes into abutting engagement against the corresponding axial abutment surface 17 of the sprocket-carrying body, thus acting as reference for the axial positioning of the monolithic set 26, preventing the axial sliding thereof.

(30) Towards the inside in the axial direction (i.e. towards the hub 10), the entire cogset 20 (i.e. the monolithic sets 21, 22 and 26 and the sprockets 23-25) is held by the end stop 18; towards the outside in the axial direction, the cogset 20 is held by a ring nut 28, inserted on the pin 11 and screwed to the sprocket-carrying body 14, by means of an outer threaded portion 29 of the ring nut 28 and a radially inner threaded portion 30 of the sprocket-carrying body 14. The ring nut 28 has a flange 31 that goes into abutment axially against the outer face of the monolithic set 26. The clamping of the ring nut 28, with the axial pressure on the cogset 20 exerted by the flange 31 and by the end stop 18, ensures that the entire cogset 20 is locked on the sprocket-carrying body 14.

(31) In use, the coupling of the monolithic set 26 with the sprocket-carrying body 14 is particularly solid, thanks to the engagement of the projections 32 in the grooves 16, and thus ensures high precision of actuation.

(32) The monolithic set 26 shown in FIGS. 1-5, as stated, comprises the three smallest sprockets 26a, 26b and 26c of the cogset 20. According to the invention, however, the number of sprockets of the monolithic set can also be higher, up to 6. FIGS. 6-8, for example, show a monolithic set 126 (quadruplet) that groups together the four smallest sprockets 126a, 126b, 126c and 126d, having 12, 11, 10 and 9 teeth respectively.

(33) In the monolithic set 126, the radially inner projections 132 are formed at the two largest sprockets 126a and 126b. In general, when the number of smallest sprockets grouped in a monolithic set increases, it is possible to ensure that the radially inner projections are formed at more than one sprocket, so as to increase the solidity of the coupling. If the number of smallest sprockets grouped in a monolithic set becomes particularly high, for example 5 or 6, it is undoubtedly preferable for the radially inner projections to be formed at more than one sprocket, for example 2 or 3, so as to reduce the axial extension of the cantilevered portion of the monolithic set, thus increasing the torsional rigidity of the monolithic set itself; this provision also facilitates the precision of actuation of a gearshift that uses this sub-assembly.