U.S. patent application number 11/592653 was filed with the patent office on 2007-03-08 for sprocket support member for a bicycle sprocket assembly.
This patent application is currently assigned to Campagnolo S.r.l.. Invention is credited to Maurizio Valle.
Application Number | 20070054770 11/592653 |
Document ID | / |
Family ID | 32011076 |
Filed Date | 2007-03-08 |
United States Patent
Application |
20070054770 |
Kind Code |
A1 |
Valle; Maurizio |
March 8, 2007 |
Sprocket support member for a bicycle sprocket assembly
Abstract
A bicycle sprocket assembly having at least one subassembly
including a sprocket support member and two sprockets is presented.
The support member has at least one engagement portion for coupling
it to a bicycle freewheel and at least one fastening portion
arranged in a radially external position with respect to the
engagement portion. Both sprockets are fixed on the sprocket
support member on the same side of the fastening portion.
Inventors: |
Valle; Maurizio; (Vicenza,
IT) |
Correspondence
Address: |
VOLPE AND KOENIG, P.C.
UNITED PLAZA, SUITE 1600
30 SOUTH 17TH STREET
PHILADELPHIA
PA
19103
US
|
Assignee: |
Campagnolo S.r.l.
Vicenza
IT
|
Family ID: |
32011076 |
Appl. No.: |
11/592653 |
Filed: |
November 3, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10616830 |
Jul 10, 2003 |
7131656 |
|
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11592653 |
Nov 3, 2006 |
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Current U.S.
Class: |
474/160 |
Current CPC
Class: |
B62M 9/10 20130101 |
Class at
Publication: |
474/160 |
International
Class: |
F16H 55/30 20060101
F16H055/30; F16H 55/12 20060101 F16H055/12 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 11, 2002 |
EP |
02425621.6 |
Claims
1. A sprocket support member for a bicycle sprocket assembly, the
sprocket support member comprising: at least one freewheel hub
engagement portion having at least one tooth engagable with a
splined surface of a bicycle freewheel hub; and at least one
fastening portion having at least one hole for mounting the
sprocket support member to at least one sprocket, the fastening
portion lies in a first plane and the engagement portion lies in a
second plane which is axially displaced from and parallel to the
first plane.
2. The sprocket support member of claim 1, wherein the fastening
portion has an axial thickness substantially equal to a desired
axial distance between multiple sprockets of the sprocket
assembly.
3. The sprocket support member of claim 1, including an axial
projection located between the engagement portion and the fastening
portion.
4. The sprocket support member of claim 3, wherein the axial
projection forms a support against which a radially projecting
portion of a fastening element can rest.
5. The sprocket support member of claim 4, wherein the axial
projection has a centering and support seat having the shape of a
cylindrical sector coaxial with a fastening hole of the fastening
portion.
6. The sprocket support member of claim 4, wherein the axial
projection is located at the base of a radial contact surface of
the fastening portion.
7. The sprocket support member of claim 1, wherein one of the at
least one fastening portion and one of the at least one engagement
portion form at least one single structural unit, the one of the at
least one engagement portion being aligned with the one of the at
least one fastening portion in a radial direction.
8. The sprocket support member of claim 7, wherein the structural
unit includes at least one weight-saving cavity located between the
engagement portion and the fastening portion.
9. The sprocket support member of claim 7, including a plurality of
single structural units angularly equidistant from each other and
connected together by zones having reduced dimensions in the radial
direction.
10. The sprocket support member of claim 1, wherein the support
member is made of a material chosen among the group consisting of:
steel, aluminum and its alloys, titanium, and fabric made of
structural fibers incorporated in a matrix of plastic material, in
which the fibers are chosen among carbon fibers, glass fibers,
aramid fibers, boron fibers, ceramic fibers or any combination
thereof.
11. A sprocket support member for a bicycle sprocket assembly
comprising: an inner engagement portion having at least one tooth
adapted for engagement with a spline of a bicycle freewheel hub,
the inner engagement portion defining a first plane; and, an outer
fastening portion having at least one position defined for the
mounting the sprocket support member to a sprocket, the outer
fastening portion defines a second plane that is immediately
adjacent to and parallel with the first plane.
12. The sprocket support member of claim 11 wherein the inner
engagement portion and the outer fastening portion have adjacent
faces and free faces and wherein the free face of the inner
engagement portion is spaced from the free face of the outer
fastening portion by a predetermined distance adapted for a defined
sprocket assembly.
13. A sprocket support member for a bicycle sprocket assembly
comprising: an inner engagement portion having at least one tooth
adapted for engagement with a spline of a bicycle freewheel hub,
the inner engagement portion defining a first plane; and, an outer
fastening portion having at least one position defined for the
mounting the sprocket support member to a sprocket, the outer
fastening portion defines a second plane that is immediately
tangent to and parallel with the first plane.
14. A sprocket assembly for a bicycle comprising: at least one
subgroup including a sprocket support member comprising at least
one engagement portion provided with means for coupling with a
bicycle freewheel and at least one fastening portion arranged in a
radially external position with respect to the engagement portion,
the fastening portion presenting at least one hole for the mounting
of at least one sprocket to the sprocket support member, wherein
the fastening portion is axially displaced with respect to the
engagement portion; and at least two sprockets fixed to the
fastening portion, wherein at least two of the sprockets are fixed
on the same side of the fastening portion.
15. The sprocket assembly of claim 14, including a plurality of
fastening elements for mounting at least a first and a second
sprocket against a contact surface of the sprocket support
member.
16. The sprocket assembly of claim 15, including at least one
spacer means located between the first and second sprockets.
17. The sprocket assembly of claim 16, wherein the spacer means
includes two mutually opposite contact surfaces against which
respective contact portions of the first and second sprockets
rest.
18. The sprocket assembly of claim 17, wherein the contact surfaces
of the spacer means are parallel to the contact surface of the
fastening portion.
19. The sprocket assembly of claim 15, wherein the fastening
elements carry the spacer means.
20. The sprocket assembly of claim 19, wherein the spacer means is
integrated with the fastening elements.
21. The sprocket assembly of claim 20, wherein each of the
fastening elements includes an integral shoulder with two opposing
contact surfaces.
22. The sprocket assembly of claim 14, wherein each of the
fastening elements has a first cylindrical portion that engages two
aligned coaxial holes of the fastening portion and the first
sprocket.
23. The sprocket assembly of claim 22, wherein each of the
fastening elements has a second cylindrical surface that engages a
hole of the second sprocket.
24. The sprocket assembly of claim 23, wherein each of the
fastening elements includes a radial shoulder between the first and
the second cylindrical portion.
25. The sprocket assembly of claim 14, wherein each of the
fastening elements has a first head with an outer surface
substantially flush with an outer surface of the fastening
portion.
26. The sprocket assembly of claim 25, wherein each of the
fastening elements has a second head with an outer surface
substantially flush with an outer surface of the second
sprocket.
27. The sprocket assembly of claim 14, wherein each of the
fastening elements has a radially projecting portion arranged to
make contact with an axial projection located in a radially
internal position with respect to the fastening portion.
28. The sprocket assembly of claim 14, wherein each of the
fastening elements is a rivet.
29. A sprocket assembly for a bicycle, including a plurality of
subgroups, each of which includes: a sprocket support member having
at least one engagement portion shaped to engage a bicycle
freewheel hub and at least one fastening portion arranged in a
radially external position with respect to the engagement portion;
and at least two sprockets attached to the fastening portion;
wherein the subgroups can be axially mounted on the bicycle wheel
hub in contact with each other.
30. The sprocket assembly of claim 29, wherein the fastening
portion of at least one of the subgroups has an axial thickness
substantially equal to the desired distance between two adjacent
sprockets belonging to two different, mutually adjacent
subgroups.
31. The sprocket assembly of claim 30, wherein the fastening
portion of at least one of the subgroups has an outer radial
surface that rests against an outer radial surface of a sprocket of
an adjacent subgroup.
32. The sprocket assembly of claim 29, wherein the at least two
sprockets are spaced apart from each other by a distance
substantially equal to the axial thickness of the fastening
portion.
33. A bicycle sprocket assembly comprising: a sprocket support
member having: a planar frame defining a first plane; a plurality
of fastening tabs fixed to and extending radially-outwardly from
the frame and being co-planar with the frame, each tab having a
through hole; an annular step fixed to and extending axially from
the planar frame; a plurality of engagement teeth fixed to and
extending radially-inwardly from the annular step and defining a
second plane axially-spaced from the first plane; and, a pair of
sprockets mounted on the support member and arranged so that both
sprockets are positioned on the same side of the first plane and at
least a portion of the first sprocket and a portion of the second
sprocket are positioned on opposite sides of the second plane.
34. A bicycle sprocket assembly comprising: a sprocket support
member having: a planar frame defining a first plane; a plurality
of fastening surfaces on the frame, each surface having a through
hole; an annular step fixed to and extending transverse to the
planar frame; a plurality of engagement teeth fixed to and
extending radially-inwardly from the annular step and defining a
second plane axially-spaced from the first plane; a plurality of
fasteners; a pair of sprockets having radially-inwardly projecting
fastening tabs with a through hole, the sprockets being fixed on
the same side of the support member by inserting one of the
fasteners within aligned through holes in the sprocket fastening
tabs and the support member fastening surfaces; and means for
radially supporting each of the fasteners and the fastening tabs of
at least one of the sprockets.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a Continuation of U.S. patent
application Ser. No. 10/616,830, filed Jul. 10, 2003, which is
incorporated by reference as if fully set forth.
FIELD OF INVENTION
[0002] The present invention relates to a sprocket support member
for a sprocket assembly of a bicycle rear wheel.
BACKGROUND OF THE INVENTION
[0003] Over recent years, the number of transmission ratios
available on bicycle gear change devices has progressively
increased and sprocket assemblies for the rear wheel of a bicycle
having nine or ten sprockets are increasingly common on the market.
The progressive increase in the number of sprockets requires ever
increasing research for reducing the weight of the sprocket
assembly. In U.S. Pat. No. 5,935,034, assigned to the same assignee
as the present invention, a sprocket assembly is described that
includes a support member having a radially internal portion shaped
such that it couples with a freewheel device and a radially
external fastener portion. Two sprockets are mounted on the
opposite surfaces of the fastener portion. A third sprocket can be
mounted on the support member in addition to the first two
sprockets through a plurality of spacer bushings. U.S. Pat. No.
6,102,821 describes a sprocket assembly in which two sprockets are
fixed on opposite sides of a sprocket support member by pins that
engage with aligned holes of the sprockets and of the support
member.
[0004] With the progressive increase in the number of sprockets, in
addition to the need for reducing the weight of the assembly, there
is also the need for arranging the sprockets in positions that are
closer one to the other. As a consequence, the space available for
the sprocket support member becomes more limited. On the other
hand, this support member performs an important structural function
and it is necessary to ensure that it has high rigidity and
resistance characteristics.
SUMMARY OF THE INVENTION
[0005] The present invention addresses the prior art's shortcomings
by using a sprocket support member for a bicycle sprocket assembly
comprising at least one engagement portion provided with means for
coupling with a bicycle freewheel and at least one fastening
portion arranged in a radially external position with respect to
said engagement portion. The fastening portion has at least one
hole for the mounting of at least one sprocket to the sprocket
support member, wherein said fastening portion is axially displaced
with respect to said engagement portion.
BRIEF DESCRIPTION OF THE DRAWING(S)
[0006] The sprocket support member according to the present
invention will become evident through the detailed description that
follows, provided purely as a non-limiting example. In the detailed
description, the following Figures are discussed.
[0007] FIG. 1 is a partial cross-sectional side view of part of a
sprocket assembly according to the present invention.
[0008] FIG. 2 is a perspective rear view of the sprocket assembly
in FIG. 1.
[0009] FIG. 3 is a front elevation of a sprocket support member
according to the present invention.
[0010] FIG. 4 is a cross-section along the line IV-IV in FIG.
3.
[0011] FIG. 5 is a front elevation of a subgroup indicated by the
arrow V in FIG. 1.
[0012] FIG. 6 is a cross-section along the line VI-VI in FIG.
5.
[0013] FIG. 7 is an enlarged-scale cross-section of the detail
indicated by the arrow VII in FIG. 6.
[0014] FIG. 8 is a front elevation of a second embodiment of the
sprocket support member according to the invention.
[0015] FIG. 9 is a cross-section along the arrow IX-IX in FIG.
8.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0016] With reference to FIG. 1, reference number 10 indicates part
of a bicycle sprocket assembly that is intended for a rear or
driven wheel. The sprocket assembly illustrated in FIG. 1 normally
includes ten sprockets, although only six of them are shown. The
sprocket assembly 10 is configured to be mounted on the hub of a
freewheel device having external splines as shown in U.S. Pat. No.
5,935,034 which is incorporated herein by reference.
[0017] In the embodiment illustrated in FIG. 1, the sprocket
assembly 10 comprises individual sprockets 15-20, each fitted with
respective internal radial teeth 35 that directly engage with the
splined surface of the hub of the freewheel device, separated from
each other in the axial direction by spacer rings.
[0018] The individual sprockets 15, 16, 17, 18, 19, 20 are fixed
together in pairs, 15 and 16, 17 and 18, 19 and 20 in the manner
that will be described below. The sprocket pairs form three
subgroups, indicated in FIG. 1 as 28, 29 and 30. The sprockets
15-20 are connected to the sprocket support members indicated as
31,32 and 33.
[0019] FIG. 1 shows the subgroups 28, 29 and 30 preferably mounted
in mutually adjacent positions without the interposition of any
spacer. The outer surface of the fastening portion of subgroup 28
rests against the outer surface of sprocket 17, belonging to
subgroup 29, and the outer surface of the fastening portion of
subgroup 29 rests against the outer surface of sprocket 19,
belonging to subgroup 30. Thus, the fastening portions 37 of the
intermediate subgroups 28 and 29 also perform the function of
spacer members between adjacent subgroups and the sprockets
thereon. It is important to note that the fastening portions 37,
which perform the function of spacer members, are in a radially
external zone close to the sprocket teeth. This permits the
precision of the spacer distance between the sprockets to be
significantly improved.
[0020] To perform this spacing function, the fastening portions 37
have a thickness, in the axial direction, equal to the desired
distance between two adjacent sprockets. As shown in FIG. 1, the
fastening portions 37 have a thickness that is preferably equal to
the thickness of the radial shoulders 52 of the fastening elements
48 that perform the function of spacer elements between the two
sprockets of the paired subgroup. Thus, with multiple sprockets
mounted with multiple subgroups, the distance between each adjacent
sprocket is the same.
[0021] With reference to FIGS. 3 and 4, the sprocket support member
33 of subgroup 30 includes a plurality of engagement portions 34
each of which is constituted by an integral formation radially
projecting inwardly and provided with a respective tooth 35. The
teeth 35 of the engagement portions 34 are shaped so as to engage
the splined surface of the hub of a freewheel device. For example,
the engagement portions 34 are angularly spaced out, at 90.degree.
from each other by a weight-reducing hollow zone or recess 36 which
further opens the central internal opening of the sprocket support
member 33.
[0022] The sprocket support member 33 includes a plurality of
fastening portions 37, arranged in radially in external positions
with respect to and opposite the engagement portions 34. In the
embodiment illustrated in the figures, the four fastening portions
37 are angularly spaced out at 90.degree. from each other.
Preferably the fastening portions 37 are on centerlines with the
associated teeth 35. Each of these structural units is provided
with an additional weight-saving cavity 39 located between the
engagement portion 34 and the fastening portion 37. From the
structural point of view, the sprocket support member 33 results to
be formed by a series of equidistant structural units, each of
which includes an engagement portion 34 and a fastening portion 37,
the individual structural units being connected to each other by
zones 38 of smaller radial dimensions.
[0023] The fastening portions 37 are axially displaced with respect
to the engagement portions 34. More precisely, the fastening
portions 37 are contained in a first plane 37' orthogonal to the
rotational axis of the sprocket support member 33, and the
engagement portions 34 are contained in a second plane 34' parallel
to the first, see FIG. 4.
[0024] Each fastening portion 37 includes a contact surface 40 and
an outer surface 41. The surfaces 40 and 41 are preferably oriented
in a radial direction and are mutually parallel. Each fastening
portion 37 defines a mounting through hole 42. Preferably, each
mounting hole 42 includes an enlarged portion 43 where it opens
onto the outer surface 41.
[0025] Each fastening portion 37 includes an axial projection 44
located at the base of the contact surface 40. The axial, generally
circular projection 44 creates a step between fastening portions 37
and the generally circular engagement portions 34. In practice, the
axial projection 44 is formed by an axial displacement of the
fastening portions 37 with respect to the engagement portions 34.
Centering and support seats 45 are formed on the axial projections
44; each seat has the shape of a cylindrical sector coaxial with
the respective fastening hole 42. The seat and fastening hole 42
are aligned to receiver a fastener.
[0026] With reference to FIGS. 5 to 7, the two sprockets 19, 20 are
fixed on the same side of the fastening portion 37. The sprockets
19 and 20 are provided with respective holes 46 and 47, which are
mutually coaxial and coaxial with the fastening holes 42 of the
fastening portions 37. The fastening of the sprockets 19, 20 on the
sprocket support member 33 is made by a plurality of fastening
elements 48.
[0027] With reference to FIG. 7, each fastening element 48 includes
a first head 50, a first cylindrical portion 51, a radial shoulder
52, a second cylindrical portion 53 and a second head 54. The
radial shoulder 52 includes two opposing, mutually parallel radial
faces 55 and 56. The first head 50 of each fastening element 48
engages the enlarged hole portion 43, such that the outer surface
of the head 50 is substantially flush with the outer surface 41.
The first cylindrical portion 51 engages the fastening hole 42 and
the hole 47 of the sprocket 20 and the second cylindrical portion
53 engages the hole 46 of the sprocket 19. The second head 54
engages an enlarged hole portion 57 such that the outer surface of
the second head 54 is substantially flush with the outer surface 58
of the sprocket 19. After insertion of the cylindrical portions 51
and 53 of the fastening element 48 in the holes 42,47 and 46, the
heads 50, 54 of each fastening element 48 are deformed through
riveting. The radial shoulder 52 constitutes a spacer element
between the sprockets 19, 20. Part of the cylindrical surface of
the radial shoulder 52 rests against the surface of the centering
and support seat 45.
[0028] It will be understood that from the structural point of view
that each fastening element 48 behaves like a beam resting on the
hole 42 and the centering and support seat 45. The sprocket 20 is
attached by four of the fastening elements 48 located as described.
This allows a highly rigid connection to be achieved. Only the
sprocket 19 is surface mounted on the fastening element 48. From
the point of view of the connection rigidity, the solution
according to the present invention is superior to those of the
prior art in which the sprockets are fixed by opposite parts of the
fastening portion of the sprocket support member, because in the
solutions according to the prior art both of the sprockets are
surface mounted.
[0029] Each sprocket subgroup 31, 32,33, is aligned on a wheel hub
(not shown) using the engagement portions 34 and teeth 35 to align
the sprocket subgroups on the wheel hub. Once aligned, the
subgroups are tightened to the wheel hub using a standard fastener,
generally known as a quick-release.
[0030] The sprocket support member 33 can be obtained through hot
or cold plastic deformation or through material removal machining
and can be made of steel, aluminum and its alloys, titanium or any
other metallic material with good strength, hardness, and weight
characteristics. The sprocket support member 33 can also be
obtained through mould reticulation of a fabric made of structural
fibers incorporated in a matrix of plastic material. The fibers are
preferably either carbon fibers, glass fibers, aramid fibers, boron
fibers, ceramic fibers or any combination thereof.
[0031] The shape of each sprocket support member 31, 32, 33 could
differ from that illustrated. In a second embodiment of the
sprocket support member 133 illustrated in FIGS. 8 and 9, the
fastening portions 137 could be shaped like arms that extend
outwards in a radial direction, with the zone of reduced radial
dimension 138 having concave external borders instead of the convex
ones shown in FIGS. 3 and 4. The profile of these arms could also
be straight or have a more pronounced concavity or convexity with
respect to those illustrated. In addition, the weight-saving hollow
zones or recesses 36, 39, 136, 139 could have shapes and dimensions
which are different from those illustrated so long as there is
sufficient material to preserve the structural integrity of the
zones 38 and 138 and the axial projections 44 and 144. These
dimensions will be determined to some extent by the material and
the method of production for this part.
[0032] Each fastening element 48 could be constituted by a smooth
cylindrical pin with ends to be deformed in situ to form the heads
50, 54 and the radial shoulder 52 could be substituted by a ring
inserted on the pin between the two sprockets 19, 20. The contact
surfaces 55, 56 of the radial shoulder 52 could be divergent or
convergent with respect to the axis of the fastening element 48. In
addition, each sprocket support member 31, 32, 33 could carry more
than two sprockets.
[0033] Further, the present invention could also be used for the
front gears of a bicycle transmission assembly.
* * * * *