U.S. patent application number 12/194379 was filed with the patent office on 2008-12-25 for spoked bicycle wheel, components thereof and relative manufacturing methods.
This patent application is currently assigned to CAMPAGNOLO, S.r.l.. Invention is credited to Maurizio Passarotto, Davide Urbani.
Application Number | 20080315674 12/194379 |
Document ID | / |
Family ID | 34932740 |
Filed Date | 2008-12-25 |
United States Patent
Application |
20080315674 |
Kind Code |
A1 |
Passarotto; Maurizio ; et
al. |
December 25, 2008 |
SPOKED BICYCLE WHEEL, COMPONENTS THEREOF AND RELATIVE MANUFACTURING
METHODS
Abstract
A spoked bicycle wheel is presented where the masses of a set of
spoke connections for connection of a hub and a rim as a whole are
imbalanced with respect to the rotational axis. In such a way the
dynamic imbalance of the wheel due to localized mass increases at
the valve and at a possible joint is reduced or eliminated.
Inventors: |
Passarotto; Maurizio;
(Rovigo, IT) ; Urbani; Davide; (Montecchio
Maggiore (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: |
34932740 |
Appl. No.: |
12/194379 |
Filed: |
August 19, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11215941 |
Aug 31, 2005 |
7425041 |
|
|
12194379 |
|
|
|
|
Current U.S.
Class: |
301/55 ;
29/894.341; 29/894.345; 301/104 |
Current CPC
Class: |
B60B 1/044 20130101;
B60B 21/04 20130101; Y10T 29/49522 20150115; F16F 15/324 20130101;
B60B 1/0215 20130101; B60B 1/003 20130101; B60B 21/062 20130101;
B60B 21/12 20130101; B60B 21/025 20130101; Y10T 29/49515 20150115;
B60B 1/041 20130101 |
Class at
Publication: |
301/55 ;
29/894.341; 301/104; 29/894.345 |
International
Class: |
B60B 1/02 20060101
B60B001/02; B21K 1/34 20060101 B21K001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 31, 2004 |
EP |
04425652.7 |
Claims
1. A spoked bicycle wheel comprising a hub, a rim and a set of
spoke connections connecting the hub and the rim, wherein the
masses of the set of spoke connections as a whole are imbalanced
with respect to the wheel's axis of rotation.
2. The wheel of claim 1, wherein the imbalance with respect to the
wheel's axis of rotation of the set of spoke connections
compensates for an imbalance due to at least one localized mass
increase of the wheel.
3. The wheel of claim 1, wherein said set comprises at least one
spoke connection of different mass at least than the remaining
spoke connections in a sub-set of spoke connections regular with
respect to the wheel's axis of rotation.
4. The wheel of claim 3, wherein said at least one spoke connection
of different mass is a single spoke connection.
5. The wheel of claim 3, wherein said at least one spoke connection
of different mass are two spoke connections.
6. A spoked bicycle wheel comprising a hub, a rim and a set of
spoke connections connecting the hub and the rim, said set
comprises at least one spoke connection of different mass at least
than the remaining spoke connections in a sub-set of spoke
connections regular with respect to the wheel's axis of rotation,
each spoke connection comprises a spoke and a removable connection
element at a first end of said spoke for removable connection with
the rim or with the hub, the removable connection element of at
least one spoke connection having a different mass than the
removable element of the remaining spoke connections, wherein the
masses of the set of spoke connections as a whole are imbalanced
with respect to the wheel's axis of rotation.
7. The wheel of claim 6, wherein said at least one removable
connection element of different mass connects to the rim.
8. The wheel of claim 6, wherein each removable connection element
comprises an internally threaded element coupled with an outer
threading of an end of a spoke, and wherein the internally threaded
element of at least one spoke connection has a different mass than
the internally threaded element of the remaining spoke
connections.
9. The wheel of claim 6, wherein each removable connection element
comprises an internally threaded element couplable with an outer
threading of an end of a spoke and an abutment plate, and wherein
the abutment plate of at least one spoke connection has a different
mass than the abutment plate of the remaining spoke
connections.
10. The wheel of claim 6, wherein each removable connection element
comprises an internally threaded element couplable with an outer
threading of an end of a spoke, and wherein the removable
connection element of at least one spoke connection comprises an
additional abutment plate with respect to the remaining spoke
connections.
11. The wheel of claim 3, wherein at least one spoke connection is
made from a material having a different specific density than the
remaining spoke connections.
12. The wheel of claim 11, wherein said materials of different
specific densities comprise aluminum on the one hand and steel or
brass on the other hand.
13. The wheel of claim 3, wherein said wheel comprises a first
localized mass increase at a first position, and said set comprises
at least one spoke connection of reduced mass arranged in a half of
the rim centered about said first position.
14. The wheel of claim 13, wherein said at least one spoke
connection of reduced mass is arranged adjacent to the first
position.
15. The wheel of claim 3, wherein said wheel comprises a first
localized mass increase at a first position and said set comprises
at least one spoke connection of increased mass arranged in a half
of the rim opposite the half of the rim centered about said first
position.
16. The wheel of claim 15, wherein said at least one spoke
connection of increased mass is arranged substantially
diametrically opposite said first position.
17. The wheel of claim 13, wherein said wheel comprises a second
localized mass increase, less than the first localized mass
increase.
18. The wheel of claim 17, wherein said second localized mass
increase is in an intraspoke zone substantially diametrically
opposite the first localized mass increase.
19. The wheel of claim 15, wherein said wheel comprises a second
localized mass increase, less than the first localized mass
increase.
20. The wheel of claim 19, wherein said second localized mass
increase is in an intraspoke zone substantially diametrically
opposite the first localized mass increase.
21. The wheel of claim 13, wherein said wheel further comprises a
second localized mass increase, less than said first localized mass
increase, at a second position, and said set further comprises at
least one spoke connection of reduced mass arranged in a half of
the rim centered about said second position.
22. The wheel of claim 21, wherein said at least one spoke
connection of reduced mass is arranged adjacent to said first
position.
23. The wheel of claim 15, wherein said wheel further comprises a
second localized mass increase, less than said first localized mass
increase, at a second position, and said set further comprises at
least one spoke connection of reduced mass arranged in a half of
the rim centered about said second position.
24. The wheel of claim 23, wherein said at least one spoke
connection of reduced mass is arranged substantially adjacent said
second position.
25. The wheel of claim 13, wherein said wheel further comprises a
second localized mass increase, less than said first localized mass
increase, at a second position, and said set further comprises at
least one spoke connection of increased mass arranged in a half of
the rim opposite the half of the rim centered about said second
position.
26. The wheel of claim 25, wherein said at least one spoke
connection of increased mass is arranged substantially
diametrically opposite said second position.
27. The wheel of claim 15, wherein said wheel further comprises a
second localized mass increase, less than said first localized mass
increase, at a second position, and said set further comprises at
least one spoke connection of increased mass arranged in a half of
the rim opposite the half of the rim centered about said second
position.
28. The wheel of claim 27, wherein said at least one spoke
connection of increased mass is arranged substantially
diametrically opposite said second position.
29. The wheel of claim 1, wherein the positions of the spoke
connections of said set are irregularly arranged about the rotation
axis of the wheel.
30. The wheel of claim 29, wherein said set comprises a sub-set of
spoke connections balanced with respect to the rotation axis and at
least one additional spoke connection.
31. The wheel of claim 30, wherein said balanced sub-set of spoke
connections comprises groups of closer spoke connections, said
groups being regularly arranged about the rim.
32. The wheel of claim 30, wherein said at least one additional
spoke connection is/are not tensioned.
33. The wheel of claim 30, wherein said at least one additional
spoke connection is/are equal to at least some of the spoke
connections of the balanced sub-set.
34. The wheel of claim 30, wherein said at least one additional
spoke connection has/have a different mass than at least some of
the spoke connections of the balanced sub-set.
35. The wheel of claim 34, wherein at least part of said at least
one additional spoke connection is/are made of a material with
different specific density than said at least some of the spoke
connections of the balanced sub-set.
36. The wheel of claim 35, wherein said at least one additional
spoke connection is/are at least partly made of plastic.
37. The wheel of claim 30, wherein said at least one additional
spoke connection comprises a single additional spoke
connection.
38. The wheel of claim 30, wherein said at least one additional
spoke connection comprises only two additional spoke
connections.
39. The wheel of claim 30, wherein said wheel comprises a first
localized mass increase at a first position and said at least one
additional spoke connection is arranged in the half of the rim
opposite the half of the rim centered about said first
position.
40. The wheel of claim 39, wherein said at least one additional
spoke connection is arranged substantially diametrically opposite
said first position.
41. The wheel of claim 39, wherein said wheel comprises a second
localized mass increase, less than the first localized mass
increase.
42. The wheel of claim 41, wherein said second localized mass
increase is in an intraspoke zone substantially diametrically
opposite the first localized mass increase.
43. The wheel of claim 39, wherein said wheel further comprises a
second localized mass increase, less than said first localized mass
increase, at a second position, and at least one additional spoke
connection is further arranged in the half of the rim opposite the
half of the rim centered about said second position.
44. The wheel of claim 43, wherein said at least one additional
spoke connection is arranged substantially diametrically opposite
said second position.
45. A set of spoke connections for connecting a hub and a rim of a
spoked bicycle wheel, wherein the masses of the set of spoke
connections as a whole are imbalanced with respect to the wheel's
axis of rotation.
46. A method of manufacturing a spoked bicycle wheel, comprising
the steps of providing a hub, providing a rim and connecting the
rim and the hub through a set spoke connections, wherein the masses
of the set of spoke connections as a whole are imbalanced with
respect to the wheel's axis of rotation.
47. The method according to claim 46, wherein said spoke
connections are so arranged as to compensate for an imbalance due
to at least one localized mass increase of the wheel.
48. A spoke for the wheel of claim 1, comprising first and second
end portions; and an intermediate portion of greater
cross-sectional area than its end portions.
49. The spoke of claim 48, wherein the intermediate portion is
flattened.
50. The spoke of claim 48, wherein the intermediate portion is
central with respect to its end portions.
51. The spoke of claim 53, wherein the intermediate portion is
closer to an end portion of the spoke towards the rim.
52. A method of manufacturing a spoke for the wheel of claim 1,
comprising the steps of: i) providing a metal cylindrical wire
having a first diameter (d1), ii) reducing the diameter of a
predetermined length of wire to a second diameter (d2) along a
first and second end portion of said predetermined length of wire,
iii) cutting said predetermined length of said wire, iv) forming
hub attachment means at said first end portion, and v) forming rim
attachment means along at least part of said second end
portion.
53. The method of claim 52, further comprising the step of vi)
flattening the portion of wire between said first and said second
end portions.
54. The method of claim 52, further comprising the step of vii)
bending said first end portion.
55. The method of claim 52, wherein said step ii) is carried out by
drawing or hammering.
56. The method of claim 52, wherein said first diameter (d1) is 2.3
millimeters and said second diameter (d2) is 2 millimeters.
57. The method of claim 52, wherein said rim attachment means
comprise an outer threading.
58. The method of claim 52, wherein said hub attachment means
comprise a head.
59. The method of claim 52, wherein said step iv) is carried out by
upsetting.
60. A spoked bicycle wheel comprising a hub, a rim comprising a
joint zone, a plurality of spoke connections that connect the hub
and the rim, and a valve fitted to the rim essentially
diametrically opposite the joint zone, a mass of the valve being
less than a mass of the joint zone, wherein the spoke connections
comprise one spoke connection of increased mass with respect to the
remaining spoke connections, arranged adjacent to the valve.
61. A spoked bicycle wheel comprising a hub, a rim comprising a
joint zone, a plurality of spoke connections that connect the hub
and the rim, and a valve fitted to the rim not diametrically
opposite the joint zone, a mass of the valve being less than a mass
of the joint zone, wherein the spoke connections comprise at least
one spoke connection of increased mass with respect to the
remaining spoke connections, arranged on the other side of a
diameter passing through the joint zone than the valve.
62. A spoked bicycle wheel comprising a hub, a composite rim, a
plurality of spoke connections that connect the hub and the rim,
and a valve fitted to the rim, wherein the spoke connections
comprise at least one spoke connection of increased mass with
respect to the remaining spoke connections, arranged essentially
diametrically opposite the valve.
63. A spoked bicycle wheel comprising a hub, a rim comprising a
joint zone, a plurality of spoke connections that connect the hub
and the rim, and a valve fitted to the rim essentially
diametrically opposite the joint zone, a mass of the valve being
less than a mass of the joint zone, wherein the spoke connections
comprise at least one spoke connection of reduced mass with respect
to the remaining spoke connections, arranged adjacent the joint
zone.
64. A spoked bicycle wheel comprising a hub, a rim and a plurality
of spoke connections that connect the hub and the rim, wherein the
spoke connections are arranged to counteract an imbalance with
respect to a wheel's axis of rotation, said imbalance being the
result of at least one localized mass variation of the wheel.
65. A spoked bicycle wheel comprising a hub, a rim and a plurality
of spoke connections that connect the hub and the rim, wherein at
least one of said spoke connections has a different mass than the
remaining spoke connections arranged to counteract an imbalance
with respect to a wheel's axis of rotation, said imbalance being
the result of at least one localized mass increase of the
wheel.
66. A spoked bicycle wheel comprising a hub, a rim and a plurality
of spoke connections that connect the hub and the rim, wherein the
spoke of at least one spoke connection has a different mass than
the spokes of other spoke connections and is arranged to counteract
an imbalance with respect to a wheel's axis of rotation, said
imbalance being the result of at least one localized mass increase
of the rim.
67. A spoked bicycle wheel comprising a hub, a rim and a plurality
of spoke connections that connect the hub and the rim, wherein the
spoke connections are arranged to counteract an imbalance with
respect to a wheel's axis of rotation, said imbalance being the
result of at least a first localized mass increase at a first
position of the rim, and wherein said plurality of spoke
connections comprises at least one spoke connection of reduced mass
arranged in a half of the rim centered about said first
position.
68. A spoked bicycle wheel comprising a hub, a rim and a plurality
of spoke connections that connect the hub and the rim, wherein the
spoke connections are arranged to counteract an imbalance with
respect to a wheel's axis of rotation, said imbalance being the
result of at least a first localized mass increase at a first
position of the rim and wherein said plurality of spoke connections
comprises at least one spoke connection of increased mass arranged
in the half of the rim opposite a half of the rim centered about
said first position.
69. A spoked bicycle wheel comprising a hub, a rim and a plurality
of spoke connections that connect the hub and the rim, wherein the
spoke connections are arranged to counteract an imbalance with
respect to a wheel's axis of rotation, said imbalance being the
result of at least a first localized mass increase at a first
position of the rim and wherein said plurality of spoke connections
comprises at least one spoke connection of increased mass arranged
substantially diametrically opposite said first position.
70. A dynamically balanced bicycle wheel comprising: a hub; a rim;
and, a plurality of spoke connections connecting the hub and the
rim, wherein at least one of the plurality of spoke connections has
a selected mass and location that renders the bicycle wheel
dynamically balanced with respect to an axis of rotation extending
through the hub.
71. A dynamically balanced bicycle wheel comprising: a hub; a rim;
a valve; a plurality of spokes connecting the hub and the rim; and,
a balancing element having a mass and location that renders the
bicycle wheel dynamically balanced with respect to an axis of
rotation extending through the hub.
72. The wheel of claim 71 wherein the balancing element is one of
the plurality of spokes.
73. The wheel of claim 72 wherein the balancing spoke is of a
different geometric configuration than the remainder of the
plurality of spokes.
74. The wheel of claim 71 wherein the balancing element is
comprised of at least two spokes of the plurality of spokes.
75. The wheel of claim 74 wherein the at least two balancing spokes
of the plurality of spokes are generally adjacent the valve.
76. The wheel of claim 74 wherein the at least two balancing spokes
of the plurality of spokes are of a geometric shape that is
different than the remainder of the plurality of spokes.
77. The wheel of claim 71 wherein the balancing element is at least
one additional spoke.
78. The wheel of claim 77 wherein the at least one additional spoke
is not tensioned.
79. The wheel of claim 77 wherein the at least one additional spoke
has substantially the same mass as the remainder of the plurality
of spokes.
80. A dynamically balanced bicycle wheel comprising: a hub; a rim;
a valve; a plurality of spokes extending between the hub and the
rim; a plurality of connectors that connect the spokes to the rim;
and, a balancing element having a mass and location that renders
the bicycle wheel dynamically balanced with respect to an axis of
rotation extending through the hub.
81. The wheel of claim 80 wherein the balancing element is one of
the plurality of connectors.
82. The wheel of claim 80 wherein the balancing element is
comprised of at least two of the plurality of connectors.
83. The wheel of claim 82 wherein the at least two balancing
connectors of the plurality of connectors are located generally
adjacent the valve.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/215,941 filed Aug. 31, 2005, which is
incorporated by reference as if fully set forth.
FIELD OF THE INVENTION
[0002] The present invention concerns in general the field of
spoked bicycle wheels, and in particular a wheel, a set of spoke
connections and a spoke therefor, as well as a method for
manufacturing the wheel and the spoke.
BACKGROUND OF THE INVENTION
[0003] A spoked bicycle wheel conventionally includes a rim, a hub
and a set of spoke connections between the rim and the hub.
[0004] More specifically, for the connection between rim and hub, a
spoke having a widened head at a first end and an outer threading
at a second end opposite the first end is typically provided.
[0005] The widened head of the spoke is received in a suitably
shaped seat, usually made at the hub or at a flange thereof. In
order to allow the extension of the spoke in the radial or
substantially radial direction, a bend is typically provided close
to the first end of the spoke. The bend of the spoke at the first
end can, however, be left out.
[0006] The threading at the second end of the spoke is coupled in a
threaded hole usually made at the rim or, preferably, in a
removable connection element of the nipple type or nut type, which
abuts at seating holes in the rim, possibly through the
interposition of a plate.
[0007] Spokes with different attachment portions to the rim and to
the hub are also known, for example where the head of the spoke is
intended to couple with the rim and the threading of the spoke is
intended to couple with the hub.
[0008] The present invention is not limited to any particular type
of spoke connection. In the present invention and in the attached
claims, the expression "spoke connection" is meant to indicate the
assembly of a spoke and possible removable connection elements,
such as the nipple and interposition plate discussed above.
[0009] The hub is an element with rotational symmetry with respect
to the axis of the bicycle wheel, and the spoke connections are
always so distributed along the circumference of the wheel that the
center of mass of them as a whole is at the axis of the wheel. More
specifically, the spoke connections can be distributed equally
spaced apart, or can be distributed equally spaced apart along the
rim in groups of two or more spoke connections.
[0010] Due to the different angle of the spoke connections with
respect to the median plane of the wheel (camber) between one side
and the other of the hub and/or due to a tangential attachment of
the spokes to a side of the hub and/or for other reasons in
particularly complex spoke patterns, there can be spoke connections
of varying masses, but still forming regular, with respect to the
rotation axis, sub-sets of identical spoke connections. Also in
such cases, the center of mass of the set of spoke connections is
therefore at the rotation axis of the wheel, in other words the set
of spoke connections is balanced with respect to the rotation
axis.
[0011] The known geometries of rims are such that also the rim is
an element with rotational symmetry with respect to the axis of the
wheel.
[0012] In first analysis, the wheel is therefore dynamically
balanced.
[0013] In practice, there is however always a cause for an
imbalance or a localized mass increase, due to the valve that
retains the air inside the pneumatic tire, be it of the type with
an inner tube, of the tubeless type or of the type with a tubular
tire. The valve, fixed in a proper hole formed in the rim, is
typically made of brass and has standard size and therefore
predetermined weight. The slight lightening of the rim as a result
of the housing hole provided for the valve is insufficient to
compensate for the localized mass increase of the valve itself. On
the contrary, in rims obtained by carbon fiber molding, the
localized mass increase at the valve is sometimes accompanied by a
further increase in mass due to the presence of a greater thickness
of the rim in such a zone in order to compensate for the weakening
of the rim due to the hole for the valve.
[0014] The cause for imbalance provided by the valve is
accompanied, in the case of metal rims, by a second cause. Metal
rims, in particular those made of steel or aluminum alloy, are made
through a rod extruded according to the desired section of the rim,
the rod then being shaped into a circumference by calendaring. The
jointing of the ends of the rod is carried out in various ways, all
of which however provide for the addition of material and therefore
determine a localized mass increase. For example, known methods for
carrying out jointing provide for: the insertion with interference
of one or more pins in respective holes butt formed in the wall of
the ends of the extruded rod; the insertion of a sleeve in an inner
chamber of the extruded rod for a certain extent from both ends,
possibly with the addition of an adhesive; and the butt welding of
the ends, carried out with or without addition of welding material,
but in any case, using solid metal inserts in the inner chamber of
the extruded rod in order to allow for gripping the ends with
suitable pincers during welding without the risk of deforming the
rim.
[0015] One or both of the causes for localized mass increase bring
about that the center of mass of the masses of the wheel does not
belong to the rotation axis of the wheel. From a dynamic point of
view, the imbalance caused by such localized mass increases brings
about an unfavorable instability of the wheel. Moreover, given that
the imbalance increases as the speed of the wheel increases, it
becomes more dangerous precisely when a very stable wheel is
needed, i.e. when the travel speed is fast, like when going
downhill.
[0016] In the case of metal rims, to reduce the problem of dynamic
imbalance, it is known to make the hole for the valve in a position
diametrically opposite the joint of the extruded rod. The balancing
of the masses in movement thus obtained is, however, insufficient
to provide good stability of the wheel since typically the
additional mass in the zone of the joint is different from,
normally greater than, the mass of the valve body. Moreover, in the
case of wheels with odd spoke patterns, it is sometimes not
possible to make the hole for the valve in a position diametrically
opposite the joint of the extruded rod, but only in an
approximately opposite position since the diametrically opposite
position is occupied by a spoke or by a group of spokes. The
resultant of the centrifugal forces cannot, therefore, be cancelled
out due to the mass difference and/or due to the angle that the
forces due to the two localized mass increases form between
them.
[0017] It has also been attempted to solve the problem of balancing
in such rims by sticking a plate at the valve hole. By providing an
additional element, such a provision is, however, unsatisfactory
both from the manufacture point of view and from the point of view
of the end product, since, besides increasing the weight of the
rim, the plate risks detaching with the use of the bicycle, is
unaesthetic and not aerodynamic.
[0018] The technical problem at the basis of the present invention
is to effectively reduce the dynamic imbalance of a bicycle
wheel.
SUMMARY OF THE INVENTION
[0019] The present invention relates to a spoked bicycle wheel
including a hub, a rim and a set of spoke connections connecting
the hub and the rim. The masses of the set of spoke connections, as
a whole, are imbalanced with respect to the wheel's axis of
rotation.
[0020] The invention also relates to a method of manufacturing a
spoked bicycle wheel. The method includes providing a hub, a rim,
and a set of spoke connections, the masses of the set of spoke
connections as a whole being imbalanced with respect to the wheel's
axis of rotation, and connecting the rim and the hub through the
set spoke connections.
[0021] The invention further relates to a spoke for a bicycle
wheel, the wheel includes a hub, a rim and a set of spoke
connections connecting the hub and the rim. The masses of the set
of spoke connections as a whole are imbalanced with respect to the
axis of rotation of the wheel, and the imbalance with respect to
the axis of rotation compensates for an imbalance due to at least
one localized mass increase of the wheel, the spoke comprising
first and second end portions, and an intermediate portion of
greater cross-sectional area than the end portions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The invention shall be better described hereafter with
reference to some embodiments and examples, based upon the attached
drawings, wherein corresponding elements are designated by similar
reference numerals. In the drawings:
[0023] FIG. 1 illustrates a spoked bicycle wheel according to a
first embodiment,
[0024] FIG. 2 is a partial perspective view of a portion of rim,
with a spoke connection coupled,
[0025] FIG. 3 is a perspective view of a sleeve for jointing the
rim,
[0026] FIG. 4 is a cross-sectional view of the sleeve of FIG. 3
inserted in the rim,
[0027] FIG. 5 is a perspective view of a pair of inserts for
jointing the rim,
[0028] FIG. 6 illustrates a spoke of increased mass according to
the present invention,
[0029] FIG. 7 illustrates an alternative spoke of increased mass
according to the present invention,
[0030] FIG. 8 illustrates a spoked bicycle wheel according to a
second embodiment,
[0031] FIG. 9 illustrates a spoked bicycle wheel according to a
third embodiment,
[0032] FIG. 10 illustrates a spoked bicycle wheel according to a
fourth embodiment,
[0033] FIG. 11 illustrates a spoked bicycle wheel according to a
fifth embodiment,
[0034] FIG. 12 illustrates a spoked bicycle wheel according to a
sixth embodiment,
[0035] FIG. 13 illustrates a spoked bicycle wheel according to a
seventh embodiment,
[0036] FIG. 14 illustrates an embodiment of a spoke of reduced
mass,
[0037] FIG. 15 illustrates a spoked bicycle wheel according to an
eighth embodiment,
[0038] FIG. 16 illustrates a spoked bicycle wheel according to a
ninth embodiment,
[0039] FIG. 17 illustrates a spoked bicycle wheel according to a
tenth embodiment,
[0040] FIG. 18 illustrates a spoked bicycle wheel according to an
eleventh embodiment, and
[0041] FIG. 19 illustrates a spoked bicycle wheel according to a
twelfth embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Introduction to the Embodiments
[0042] The invention, in a first aspect thereof, concerns a spoked
bicycle wheel that includes a hub, a rim and a set of spoke
connections connecting the hub and the rim, wherein the masses of
the set of spoke connections as a whole are imbalanced with respect
to the wheel's axis of rotation.
[0043] Thus, it is possible to at least partially compensate for
localized mass increases of the wheel, in particular a joint and/or
the valve for retaining the air of the pneumatic tire.
[0044] Preferably, the imbalance, with respect to the axis of
rotation, of the set of spoke connections compensates for an
imbalance due to at least one localized mass increase of the wheel,
so that the wheel is perfectly dynamically balanced.
[0045] In particular, the set includes at least one spoke
connection of a different mass at least than the remaining spoke
connections of a sub-set of spoke connections, regular with respect
to the rotation axis.
[0046] In particularly simple and effective embodiments, there are
just one or two spoke connections of different mass.
[0047] Typically, each spoke connection includes a spoke and a
removable connection element at a first end of the spoke for
removable connection with the rim or with the hub.
[0048] In such a case, in first embodiments the spoke of at least
one spoke connection has a different mass than the spokes of other
spoke connections.
[0049] Advantageously, the at least one spoke of different mass has
an intermediate portion having a different cross-sectional area
than its end portions. In such a way, all of the end portions of
the spokes can be identical and therefore it is not necessary to
differentiate the spoke attachment seats provided in the rim and/or
in the hub, as well as it is also possible to use any removable
connection elements all equal to each other.
[0050] Furthermore, the intermediate portion can be flattened to
obtain a more aerodynamic profile of the spoke.
[0051] The intermediate portion can be central or closer to an end
portion of the spoke at the rim side. By arranging the intermediate
portion closer to the rim side, the mass difference shall cause a
greater centrifugal or centripetal force, easing the compensation
or the partial reduction in imbalances of the wheel due to
localized mass increases.
[0052] Alternatively or in addition to the spoke, the removable
connection element of at least one spoke connection can have a
different mass than the removable element of other spoke
connections.
[0053] Preferably, the removable connection element of different
mass is for connection with the rim. In such a way, the mass
difference shall cause a greater centrifugal or centripetal
force.
[0054] In particular, when each removable connection element
includes an internally threaded element coupled with an outer
threading of an end of a spoke, it can be the internally threaded
element of at least one spoke connection that has a different mass
than the internally threaded element of other spoke
connections.
[0055] Alternatively or in addition, when each removable connection
element includes an internally threaded element coupled with an
outer threading of an end of a spoke and an abutment plate, the
abutment plate of at least one spoke connection can have a
different mass than the abutment plate of other spoke
connections.
[0056] In a further alternative, the removable connection element
of at least one spoke connection can include an additional abutment
plate with respect to other spoke connections, which have just one
or do not have any.
[0057] The different mass of the spoke connections can be obtained
by using materials of different specific densities.
[0058] In particular, the materials of different specific densities
can include aluminum on the one hand and steel or brass on the
other hand.
[0059] According to some embodiments, the wheel includes a first
localized mass increase at a first position, and the set includes
at least one spoke connection of reduced mass arranged in the half
of the rim centered about the first position.
[0060] In the above context, under reduced mass it is meant reduced
with respect to a mass that would make the set balanced with
respect to the rotation axis.
[0061] The at least one spoke connection of reduced mass is
preferably arranged adjacent the first position.
[0062] According to other embodiments, the wheel includes a first
localized mass increase at a first position and the set includes at
least one spoke connection of increased mass arranged in the half
of the rim opposite the half of the rim centered about the first
position.
[0063] In the above context, under increased mass it is meant
increased with respect to a mass that would make the set balanced
with respect to the rotation axis.
[0064] The at least one spoke connection of increased mass is
preferably arranged substantially diametrically opposite the first
position.
[0065] Advantageously, the above solutions also at least partially
compensate for a second localized mass increase, less than the
first localized mass increase.
[0066] This occurs, in particular, when the second localized mass
increase is in an intraspoke zone substantially diametrically
opposite the first localized mass increase and therefore the two
localized mass increases partially compensate for each other.
[0067] However, it is possible to carry out an at least partial
compensation of two discontinuities or localized mass increases
separately.
[0068] Thus, when the wheel also includes a second localized mass
increase, less than the first localized mass increase, at a second
position, in all of the embodiments discussed above, the set can
also include at least one spoke connection of reduced mass arranged
in the half of the rim centered about the second position,
preferably arranged adjacent to the second position, or else the
set can also include at least one spoke connection of increased
mass arranged in the half of the rim opposite the half of the rim
centered about the second position, preferably arranged
substantially diametrically opposite the second position.
[0069] In other embodiments, the positions of the spoke connections
of the set are irregularly arranged about the rotation axis of the
wheel. With the imbalance of such an irregularly arranged set of
spoke connections, it is possible to partly counterbalance or
preferably to compensate for the dynamic imbalance caused by the
localized mass increase(s) of the wheel, even with spoke
connections of a same mass, and one or more spoke connections may
easily be added to an existing wheel to upgrade it to a dynamically
balanced wheel.
[0070] In preferred embodiments, the set includes a sub-set of
spoke connections balanced with respect to the rotation axis and at
least one additional spoke connection that is/are used for
compensation.
[0071] The balanced sub-set of spoke connections may include spoke
connections of different length for attachment to either side of
the hub and/or of the rim, and/or may include groups of closer
spoke connections.
[0072] Especially when the additional spoke connection/s is/are not
tensioned, the wheel may be optimized from the static point of view
also.
[0073] Preferably, the additional spoke connection/s is/are equal
to some or all of the spoke connections of the balanced sub-set. It
is thus not necessary to provide for special additional spokes.
[0074] The additional spoke connection/s may also have a different
mass than some or all of the spoke connections of the balanced
sub-set, thus providing a further degree of freedom in balancing
the localized mass increase/s of the wheel.
[0075] Additional spoke connection/s of a different mass may be
obtained in any of the ways disclosed above.
[0076] In particular, at least part of the additional spoke
connection/s may be made of a material with different specific
density than some or all of the spoke connections of the balanced
sub-set, e.g. of plastics.
[0077] In particularly simple and effective embodiments, there are
just one or two additional spoke connections.
[0078] According to some of these embodiments, the wheel includes a
first localized mass increase at a first position, and the at least
one additional spoke connection is/are arranged in the half of the
rim opposite the half of the rim centered about the first position,
preferably arranged substantially diametrically opposite the first
position.
[0079] Advantageously, the above solutions also at least partially
compensate for a second localized mass increase, less than the
first localized mass increase.
[0080] This occurs, in particular, when the second localized mass
increase is in an intraspoke zone substantially diametrically
opposite the first localized mass increase and therefore the two
localized mass increases partially compensate for each other.
[0081] However, it is possible to carry out an at least partial
compensation of two discontinuities or localized mass increases
separately.
[0082] Thus, when the wheel also includes a second localized mass
increase, less than the first localized mass increase, at a second
position, the at least one additional spoke connection can be
arranged in the half of the rim opposite the half of the rim
centered about the first position, preferably arranged
substantially diametrically opposite the first position.
[0083] In other embodiments, the set includes spoke connections in
a not uniform arrangement about the periphery of the wheel, without
there being a sub-set of spoke connections balanced with respect to
the rotation axis.
[0084] The set then includes denser regions, i.e. with a greater
number of spoke connections, and less dense regions, i.e. with a
smaller number of spoke connections, the criteria for their
arrangement with respect to the localized mass increase(s) of the
wheel being analogous to the criteria outlined above for arranging
spoke connection(s) of different mass in a sub-set of spoke
connections regular with respect to the rotation axis of the
wheel.
[0085] In a second aspect thereof, the invention concerns a set of
spoke connections as outlined above.
[0086] In a third aspect thereof, the invention concerns a method
of manufacturing a spoked bicycle wheel, by providing a hub, a rim
and a set of spoke connections for connection of the rim and the
hub, and arranging the spoke connections so that the masses of the
set of spoke connections as a whole are imbalanced with respect to
the rotation axis.
[0087] Preferably the arranging step includes arranging the spoke
connections so as to compensate for an imbalance due to at least
one localized mass increase of the wheel, so that the wheel is
perfectly dynamically balanced.
[0088] In a fourth aspect thereof, the invention concerns a spoke
for a wheel as outlined above, having an intermediate portion of
greater cross-sectional area than its end portions.
[0089] The intermediate portion can be flattened and can be central
or closer to an end portion of the spoke at the rim side.
[0090] In a fifth aspect thereof, the invention concerns a method
of manufacturing a spoke for a set of spoke connections as outlined
above by:
[0091] i) providing a metal cylindrical wire having a first
diameter,
[0092] ii) reducing the diameter of a predetermined length of wire
to a second diameter along a first and second end portions of the
predetermined length of wire,
[0093] iii) cutting the predetermined length of the wire,
[0094] iv) forming the first end portion for hub attachment,
[0095] v) forming at least part of the second end portion for rim
attachment.
[0096] Cutting a predetermined length of the wire can precede or
preferably follow reducing the diameter of the wire.
[0097] The method may further include:
[0098] vi) flattening the portion of wire between the first and the
second end portions.
[0099] Alternatively or in addition, the method can also
include:
[0100] vii) bending the first end portion.
[0101] Typically ii) is carried out through drawing or
hammering.
[0102] In an embodiment, the first diameter is 2.3 millimeters and
the second diameter is 2 millimeters.
[0103] Typically, the rim attachment portion includes an outer
threading.
[0104] Typically, the hub attachment portion includes a head.
[0105] Typically, iv) is carried out through upsetting.
Description of the Embodiments
[0106] With reference to FIGS. 1 and 2, a view from the right hand
side of a wheel 11 according to the invention is shown. The shown
wheel 11, in particular a front wheel, has a flanged hub 12, a rim
13 and a set of spoke connections 14 between the hub 12 and the rim
13.
[0107] Also with reference to FIG. 2, each spoke connection 14
includes a spoke 15 and a removable connection element 16, which in
turn includes an internally threaded element 161 or nipple and an
abutment plate 162, which however can be missing.
[0108] Each spoke 15 has a head 151 at a first end, bent at a bend
152, and an outer threading 153 at a second end, opposite the first
end. Such elements of the spoke can be seen more clearly in FIGS. 6
and 7, although relative to a special spoke as described hereafter.
The bend 152 can be absent for use with a non-flanged hub
attachment, for example as illustrated in U.S. Pat. No. 6,783,192,
incorporated herein by reference.
[0109] The head 151 of each spoke is housed in a corresponding seat
121 of the hub 12. The outer threading 153 of the spoke 15 engages
in the inner threading of the internally threaded element 161,
which abuts against the rim 13 at a respective seat 131, with the
interposition of the plate 162. An opening 131a in the upper bridge
of the rim 13, for accessing the internally threaded element 161
with a tool, is also shown.
[0110] It is alternatively possible to use any alternative
configuration of the spoke connections 14, as is well known in the
field, for example in which the internally threaded element engages
with the hub 12 and the head 151 engages with the rim 13.
[0111] The spoke pattern of the wheel 11 is of the type with spoke
connections 14 distributed equally spaced apart along the
circumference of the rim 13.
[0112] The spoke pattern of the wheel 11 has an even number of
spoke connections 14, namely sixteen spoke connections, eight spoke
connections 1401r-1408r on the right hand side of the hub 12 and
eight spoke connections 1401l-1408l on the left hand side of the
hub 12.
[0113] The rim 13 is of the metal type, made by extrusion of a rod
having a suitable cross-section, its calendaring and jointing of
the ends at a jointing zone 132. The jointing in the zone 132 is
carried out by a sleeve 133, illustrated in FIG. 3, interference
fitted in the inner chamber 134 of the rim 13. As illustrated in
FIG. 4, the sleeve is inserted for a certain length from both ends
of the extruded and calendared rod. An adhesive is possibly applied
to the sleeve 133 to increase the retaining force.
[0114] As an alternative to the sleeve 133, the jointing in the
zone 132 can take place through a plurality of pins inserted in the
wall of the ends of the rim or by butt-welding the ends of the
extruded and calendared rod. In FIG. 5 a pair of solid metal
inserts 133a are illustrated, which are inserted into the inner
chamber 134 of the rim 13 to allow the ends to be gripped with
suitable pincers during welding without the risk of deforming the
rim 13.
[0115] The sleeve 133, including the optional adhesive, (or the
other equivalent elements in the jointing zone 132) has a mass m1,
which represents a mass discontinuity of the wheel 11, in
particular a localized mass increase. In a position on the rim 13
diametrically opposite the sleeve 133, a housing hole 135 is made
for a valve 7 for retaining the air in a pneumatic tire (not shown)
externally associated with the rim 13. The valve 7 is typically
made of brass and represents another mass discontinuity of the
wheel 11, in particular a localized mass increase. The localized
mass increase due to the presence of the valve 7 minus the local
reduction in mass due to the presence of the hole 135 for the valve
7 itself shall be indicated for the sake of brevity in the rest of
the description as mass m2 of the valve 7. As explained above, the
mass m1 is usually different than the mass m2, so that the wheel 1
is dynamically imbalanced, although the jointing zone 132 and the
hole 135 for the valve 7 are diametrically opposite. In most cases,
the mass m1 of the joint is greater than the mass m2 of the valve
and reference shall be made to this assumption in the present
embodiment and in the subsequent embodiments.
[0116] To reduce or even cancel out the imbalance of the wheel 11,
according to the present invention, while the spoke connections
1402r-1408r and 1401l-1408l have a mass ms, the spoke connection
1401r adjacent the hole 135 for the valve 7 has a greater mass,
ms+m3. For merely illustrative purposes, such a spoke connection
1401r of increased mass is illustrated darkened.
[0117] More specifically, the mass increase m3 of the spoke
connection 1401r can be obtained through an increase in the mass of
the spoke 1501r with respect to the remaining spokes, whereas the
removable connection elements 16 of the wheel 11 are identical to
each other.
[0118] According to an aspect of the invention, the spoke 1501r,
better represented in FIG. 6, has an intermediate portion 154 of
greater cross-section with respect to the cross-sections of the
ends bearing the head 151 and the outer threading 153, whereas the
remaining spokes are substantially cylindrical for their entire
length.
[0119] The ends bearing the head 151 and the outer threading 153 of
all sixteen spokes 15 of the spoke connections 14 are
advantageously identical, so that the set of spoke connections 14
can be used with a conventional rim 13, wherein the spoke
attachment seats 131 are all identical, and analogously can be used
for a conventional hub 12.
[0120] A process for making the spoke 1501r of increased mass
according to the present invention includes:
[0121] i) providing a cylindrical metal wire with a first diameter
d1,
[0122] ii) reducing the diameter of a predetermined length of wire
to a second diameter d2 for a certain length at first and second
ends of the predetermined length of wire to obtain the intermediate
portion 154, for example through drawing or hammering,
[0123] iii) cutting the predetermined length of the wire,
[0124] iv) forming the head 151 at the first end of the length of
wire, for the attachment to the hub 12 at the seat 121, for example
by upsetting,
[0125] v) forming the outer threading 153 at the second end of the
length of wire, for attachment to the rim 13 through screwing into
the internally threaded element 161 of the removable connection
element or nipple 16, and
[0126] vi) bending the length of wire at the bend 152.
[0127] The bending can be left out in the case of a hub with
non-flanged attachment, for example as illustrated in the cited
document U.S. Pat. No. 6,783,192. Such a spoke 1501r' of increased
mass is represented in FIG. 7.
[0128] Cutting a predetermined length of wire can precede or
preferably follow ii) reducing the diameter of the wire.
[0129] A further optional step of the method outlined above can
consist of flattening the intermediate portion of diameter d1 to
obtain a more aerodynamic profile of the spoke 1501r.
[0130] The resultant of the centrifugal forces acting in the wheel
11 under dynamic conditions can be expressed by the following
formula (I) wherein, just like in the subsequent formulae, vector
values are indicated in bold type:
F=F1+F2+F3 (1)
[0131] wherein the modules of the component forces are expressed by
the following formulae:
F1=m1*.omega..sup.2*R1 (2)
F2=m2*.omega..sup.2*R2 (3)
F3=m3*.omega..sup.2*R3 (4)
[0132] wherein .omega. stands for the angular speed of the wheel
11; R1, R2 and R3 stand for the distances from the center of the
wheel 11 to the centers of mass of the mass m1 of the joint 132, of
the mass m2 of the valve 7, and of the additional mass m3 of the
increased spoke 1501r, respectively.
[0133] It should be noted that R1, R2 and R3 are substantially
equal to each other and substantially equal to the geometric radius
R of the wheel 11, whereas R3, equal to half the length of the
spoke 1501r added to the radius of the hub 2, is approximately half
the geometric radius R of the wheel 11.
[0134] Moreover, it should be noted that the first component force
F1 in formula (I), i.e. the effect of the joint in the zone 132, is
parallel and in the opposite direction to the second component
force F2, i.e. the effect of the valve 7, and is substantially
opposite the third component force F3, i.e. the effect of the
increase in the spoke 1501r with respect to the remaining
spokes.
[0135] Even with very low values of the additional mass m3 of the
increased spoke 1501r, for example 1 or 2 grams, the value of the
resultant of the forces F gets close to zero and the dynamic
imbalance of the wheel 11 reduces with respect to a wheel in which
all sixteen spoke connections are identical to each other or in any
case are such as to form a balanced set.
[0136] On the other hand, the set of spoke connections 14 is
imbalanced, but once it is connected in the wheel between the hub
12 and the rim 13, and once the valve 7 has been fitted, the wheel
11 is less imbalanced, if not perfectly balanced.
[0137] Although in FIG. 6 the intermediate portion 154 is a central
portion of the spoke 1500r, such an intermediate portion 154 can
alternatively be decentered towards the end bearing the outer
threading 153. In such a case, it should be understood that the
center of mass of the additional mass m3 is moved further towards
the rim 13 and therefore the distance R3 in the above formula (4)
shall be greater, so that a smaller additional mass m3 shall be
sufficient to reduce the imbalance of the wheel 11.
[0138] The component forces in formula (I) due to the zone of the
joint 132 (F1) and to the valve 7 (F2) act along a diameter D
extending between them in opposite directions.
[0139] The force F3 due to the increased mass of the spoke 1501r
acts along a direction forming an angle of one thirty-second of a
revolution or 11.25.degree. with such a diameter D and therefore,
along such a diameter D, it is necessary to consider a factor
cos(11.25.degree.)=0.98.
[0140] In the above, the fact that in reality the spokes 15 are not
in the median plane of the wheel 11 (plane of FIG. 1) was
neglected, they actually extending between one and the other end of
the hub 12 to the seats 131 of the rim, which are also not
precisely in the median plane of the wheel 11. Strictly speaking,
therefore, the centrifugal force F3 lies in a plane parallel to the
median plane without, however, this introducing significant effects
on the dynamic behavior of the wheel.
Example 1
[0141] Let us consider a brass valve 7, of standard size for road
bicycles, having a mass of 6 grams and a joint with a sleeve 133
having a mass of 8.5 grams.
[0142] It is worth highlighting that the values of the masses m1
and m2 of the valve 7 and of the sleeve 133 are predetermined.
[0143] Considering such values in formulae (1)-(4) and also
considering R1=R2=R and R3=R/2, one obtains that with an additional
mass m3 of the spoke 1501r of increased mass of a little more than
5 grams the wheel 11 is substantially balanced.
[0144] Let us consider steel spokes 15 that are 286 millimeters
long and cylindrical with a diameter of 2 millimeters. The mass of
each spoke is 7.2 grams. By making the spoke of increased mass
1501r of steel, with the end portions having a diameter of 2
millimeters and an intermediate portion 154 about 240 millimeters
long with a diameter of 2.75 millimeters, a mass of the spoke 1501r
of 12.5 grams and therefore an additional mass of 5.3 grams is
obtained, suitable for the substantially perfect balancing of the
wheel 11.
[0145] It should be understood that in the wheel 11 described
above, the spoke connections 1401l-1408l at the left hand side of
the hub 12 could have a different mass ms' than the mass ms, for
example because they form a different angle with the median plane
of the wheel 11 with respect to the spoke connections of the right
hand side. Such a mass ms' could even be equal to the mass ms+m3 of
the spoke connection 1401r, without changing anything stated above
regarding the resultant F of the forces. In the same way, also
within the spoke connections 1402r-1408r of the right hand side of
the hub 12, there could be regular sub-sets of spoke connections
(for example, four spoke connections spaced apart by 90.degree.) of
a different mass than the mass ms.
[0146] A wheel 21 according to a second embodiment of the
invention, represented in FIG. 8, differs from the wheel 11 of FIG.
1 in that both of the spoke connections 2401r and 2401l adjacent to
the hole 235 for the valve 7 are of increased mass with respect to
the remaining spoke connections 2402r-2408r and 2402l-2408l. Also
in FIG. 8, the connections of increased mass are shown darkened
merely for illustrative purposes.
[0147] The resultant of the centrifugal forces acting in the wheel
21 under dynamic conditions can be expressed by the following
formula (5):
F=F1+F2+F4+F5 (5)
[0148] Wherein
F4=m4*.omega..sup.2*R4 (6)
F5=m5*.omega..sup.2*R5 (7)
[0149] wherein R4 and R5 stand for the distances from the center of
the wheel 21 to the centers of mass of the additional mass m4 of
the spoke connection of increased mass 2401r and of the additional
mass m5 of the spoke connection of increased mass 2401l,
respectively, and the remaining symbols are as described above with
reference to the first embodiment.
[0150] In case the increase of the spoke connections 2401r and
2401l is obtained through two spokes like the spoke shown in FIG. 6
or in FIG. 7, R4 and R5 are substantially equal to half the
geometric radius R of the wheel 21 (in fact, equal to half the
length of the spoke 2401r and 2401l added to the radius of the hub
22). It should also be noted that the forces F4 and F5 each form an
angle of 11.25.degree. with the diameter D extending between the
zone of the joint 32 and the valve 7, the diameter along which the
forces F1 and F2 act, in opposite directions. The resultant of the
two forces F4 and F5 therefore acts along the diameter D. The
forces F4 and F5 also strictly speaking lie in planes parallel to
the median plane of the wheel 21, but on opposite sides, and their
effect is totally negligible on the dynamic behavior of the wheel
21.
[0151] Also in this case, even with very low values of the
additional mass m4 and m5, for example 1 or 2 grams, the dynamic
imbalance of the wheel 21 is reduced with respect to a wheel in
which all of the sixteen spoke connections are identical to each
other or in any case such as to form a balanced set.
[0152] The imbalance resulting from the presence of the sleeve 133
or other type of joint and of the valve 7 can in such a case be
totally cancelled out with a suitable selection of values m4 and
m5, like in the following example, obtaining perfect balance. The
value of the resultant of the forces F is, indeed, equal to
zero.
Example 2
[0153] Under the conditions illustrated above and with the values
provided in example 1 for the masses m1 and m2, one obtains that
with additional masses m4 and m5 of the spokes of the spoke
connections 2401r and 2401l of 2.5 grams each, the wheel 21 is
perfectly balanced.
[0154] By making the spokes of the spoke connections of increased
mass 2401r and 2401 of steel, with the end portions having a
diameter of 2 millimeters and an about 265 millimeters long
intermediate portion 154 with a diameter of 2.34 millimeters, a
weight of the spokes of the spoke connections 2401r and 2401l of
9.7 grams and therefore an additional mass of 2.5 grams with
respect to the spokes of the remaining spoke connections
2402r-2408r and 2402l-2408l, of identical mass according to this
example, is obtained, suitable for the perfect balancing of the
wheel 21.
[0155] Also in the wheel 21 described above, the spoke connections
2402l-2408l on the left hand side of the hub 12 could have a
different mass ms' than the mass ms of the spoke connections
2402r-2408r, without changing anything of what stated regarding the
resultant F of the forces, of course provided that m5 in formula
(7) represents the difference in mass of the spoke connection 2401l
with respect to the spoke connections 2402l-2408l. Furthermore,
there can be, on one and/or the other side of the hub 22, sub-sets
of regular spoke connections (for example, four spoke connections
spaced apart by 90.degree.) of different mass than the mass ms.
[0156] A wheel 31 according to a third embodiment of the invention,
in particular a rear wheel, is represented in FIG. 9.
[0157] The spoke pattern of the wheel 31 has the spoke connections
distributed equally spaced apart along the circumference of the rim
33, even if they are crossed in triplets close to the hub 32.
[0158] The spoke pattern of the wheel 31 has an odd number of spoke
connections namely, twenty-one spoke connections, fourteen spoke
connections 3401r-3414r on the right hand side of the hub 32 and
seven spoke connections 3401l-3407l on the left hand side of the
hub 32.
[0159] The hole 335 for the valve 7 is not diametrically opposite
the zone 332 of the joint, a position where there is one of the
seats 131 for a spoke connection 3401r. The hole 335 for the valve
7 is therefore at an angle of about 8.5.degree. (one forty-second
of a revolution) with respect to a diameter D1 passing through the
zone 332 of the joint.
[0160] According to the invention, to reduce the dynamic imbalance
of the wheel 31 resulting from the localized masses m1 of the joint
332 and m2 of the valve 7, it is provided to use a spoke connection
of increased mass 3401l, darkened in FIG. 9 merely for illustrative
purposes.
[0161] The spoke connection of increased mass 3401l is precisely
the one adjacent the spoke connection 3401r diametrically opposite
the zone of the joint 332, on the opposite side with respect to the
valve 7, so that the centrifugal force F6 due to its additional
mass m6 with respect to the remaining spoke connections, or at
least with respect to the remaining spoke connections of a regular
sub-set of connections to which it belongs, like for example the
sub-set of spoke connections 3401r-3414r, has a component along the
diameter D1 passing through the zone of the joint 332 and a
component suitable for partially compensating for the component
perpendicular to the direction D1 of the centrifugal force due to
the valve 7.
[0162] Also in the case of the wheel 31, it is possible to reduce
the dynamic imbalance with respect to a wheel in which all of the
twenty-one spoke connections are identical to each other or in any
case are such as to form a balanced set, even with very low values,
for example 1 or 2 grams, of the additional mass of the spoke
connection 3401l and, with suitably selected values of such an
additional mass, to substantially eliminate such an imbalance.
[0163] The wheel 41 according to a fourth embodiment of the
invention, represented in FIG. 10, differs from the wheel 31 in
that there are two spoke connections of increased mass, the spoke
connection 4401r diametrically opposite the zone of the joint 432
and the spoke connection 4401l adjacent it on the opposite side
with respect to the valve 7, shown darkened merely for illustrative
purposes.
[0164] The mass increase of each of the spoke connections of
increased mass 4401r and 4401l shall be selected of a suitable
value, not necessarily equal to each other, with reference to the
masses of the localized mass increases represented by the valve 7
and by the jointing zone 432, and also with reference to the masses
of the remaining spoke connections of the set, which could all be
the same or even of different values, for example different from
one side of the hub 42 to the other.
[0165] Also in the case of the wheel 41, it is possible to reduce
the dynamic imbalance with respect to a wheel in which all of the
twenty-one spoke connections are identical to each other, or in any
case are such as to form a balanced set, even with very low values,
for example 1 or 2 grams, of the additional masses of the spoke
connections 4401r and 4401l and, with suitably selected values of
such additional masses, to substantially eliminate such an
imbalance.
[0166] It should be noted that like the force F7, which is the
effect of the additional mass m7 of the spoke connection 4401l with
respect to the remaining spoke connections, also the force F8,
which is the effect of the additional mass m8 of the spoke
connection 4401r, acts in the radial direction. The various
centrifugal forces F1, F2, F7, F8 thus act along four different
directions.
[0167] FIG. 11 represents a wheel 51, in particular a rear wheel,
according to a fifth embodiment of the invention.
[0168] The spoke pattern of the wheel 51 is identical to the one
described above with reference to the wheel 31 of FIG. 9, having an
odd number of spoke arrangements, namely twenty-one spoke
connections in crossed triplets.
[0169] In the wheel 51, the rim 53 is however made of composite
material, made by molding and reticulation or curing of a fibrous
material, for example carbon fiber, in a matrix of polymeric
material. The details on the manufacture of the rim 53 can be found
for example in EP 1 231 077, incorporated herein by reference. The
rim 53 is in a single piece, and therefore does not include a
joint.
[0170] Also in the case of the rim 53, there is nevertheless a
localized mass discontinuity or increase, represented by the valve
7. As explained above, in the zone of the hole 535 for the valve 7
the thickness of the wall of the rim can be greater than in the
rest of the rim 43. The additional mass due to the valve 7 and
possibly to the greater thickness, minus the material removed from
the hole 535 for the valve 7, is dynamically compensated for,
according to the invention, through a spoke connection of increased
mass 5404l, in the position diametrically opposite the valve 7.
Also the connection 5404l is shown darkened merely for illustrative
purposes.
[0171] The resultant of the centrifugal forces acting in the wheel
51 under dynamic conditions can be expressed by the following
formula (8):
F=F2+F3 (8)
[0172] wherein the symbols are as described above with reference to
the first embodiment. In particular, the mass increase m3 of the
spoke connection of increased mass 5404l is meant as referred to
the masses of at least the remaining spoke connections of the set
that form a regular and balanced sub-set with it, like for example
the spoke connections 5401l-5403l and 5405l-5407l.
[0173] It should be noted that the force F2, i.e. the effect of the
localized mass increase resulting from the valve 7, is parallel and
opposite the force F3, i.e. the effect of the additional mass of
the connection 5404l.
[0174] Also in the case of the wheel 51, it is possible to reduce
the dynamic imbalance with respect to a wheel in which all of the
twenty-one spoke connections are identical to each other, or in any
case are such as to form a balanced set, even with very low values,
for example 1 or 2 grams, of the additional mass of the spoke
connection 5404l and, with a suitably selected value of such an
additional mass, to substantially eliminate such an imbalance, as
illustrated by the following example.
Example 3
[0175] Let us consider a brass valve 7, of standard size for road
bicycles, with a mass of 6 grams, and let us neglect the effects of
the hole 535 for the valve 7 and of the increase in thickness about
such a hole.
[0176] The force F2, of absolute value m2*.omega..sup.2*R2, shall
be compensated by a spoke connection 5404l having an increased mass
of about 12 grams with respect to the remaining spoke connections
5401l-5403l, 505l-5407l, irrespective of the mass of the spoke
connections 5401r-5414r.
[0177] By making the spoke of increased mass 5504l of steel, with
the end portions having a diameter of 2 millimeters and an about
240 millimeters long intermediate portion 154 with a diameter of
3.4 millimeters, a mass of the increased spoke 5504l of 18.7 grams
and therefore an additional mass of 12 grams is obtained, suitable
for the substantially perfect balancing of the wheel 51.
[0178] FIG. 12 represents a wheel 61, in particular a rear wheel,
according to a sixth embodiment of the invention.
[0179] The spoke pattern of the wheel 61 includes twenty-four spoke
connections 6401l-6408l, 6401r-6416r grouped together in eight
triplets.
[0180] Also in the wheel 61, the rim 63 is made of composite
material. Therefore, there are no joints and the localized mass
increase at the valve 7 would cause a dynamic imbalance.
[0181] Such an imbalance is reduced or eliminated, according to the
invention, through two spoke connections of increased mass 6408r
and 6409r, in the two positions immediately adjacent the position
diametrically opposite the valve 7, shown darkened merely for
illustrative purposes.
[0182] The resultant of the centrifugal forces acting in the wheel
61 under dynamic conditions can be expressed by the following
formula (9):
F=F2+F4+F5 (9)
[0183] where the symbols are as described above with reference to
the first and second embodiments.
[0184] It should be noted that the sum of the forces F4 and F5,
i.e. the effects of the additional masses of the spoke connections
of increased mass 6408r and 6409r, is parallel to and opposite the
force F2, i.e. the effect of the localized mass increase due to the
valve 7.
[0185] To reduce the dynamic imbalance of the wheel 61a value of
only 1 or 2 grams of the additional masses of the spoke connections
of increased mass 6408r and 6409r is therefore sufficient.
[0186] Advantageously, the additional masses m4 and m5 shall be
selected equal to each other.
[0187] In all of the above embodiments, it is of course possible,
in the spoke connections involved on each occasion, to replace a
spoke of the type illustrated in FIGS. 6 and 7 with a spoke that is
cylindrical along its entire length and with a greater diameter
than the remaining spokes. Such a spoke can, of course, be
manufactured with a simpler process than the one outlined above,
however it is necessary to differentiate the spoke attachment seats
in the rim and the removable connection elements.
[0188] FIG. 13 represents a wheel 71 according to a seventh
embodiment of the invention, of the same type as the one
illustrated in FIG. 1.
[0189] According to FIG. 13, the dynamic imbalance resulting from
the localized mass increases in the zone 732 of the joint and at
the valve 7 is compensated through a spoke connection 7405r,
arranged adjacent the zone 732 of the joint, of reduced mass ms-m9
with respect to the remaining spoke connections 7401r-7404r,
7406r-7408r, 7401l-7408l, of mass ms. The connection of reduced
mass is shown darkened merely for illustrative purposes. Also in
this case, sub-sets of spoke connections, for example the
connections 7401l-7408l, could have a different mass ms' from the
mass ms, and even equal to the reduced mass ms-m9.
[0190] The resultant of the forces acting in the wheel 71 under
dynamic conditions is expressed by the formula (10):
F=F1+F2+F9 (10)
[0191] wherein the force F9, which is the effect of the reduced
mass of the spoke connection 7405r, is directed radially inwards
and is of module m9*.omega..sup.2*R9, and the remaining symbols are
as described above with reference to the first embodiment.
[0192] Also in the case of the wheel 71, it is possible to reduce
the dynamic imbalance with respect to a wheel in which all of the
sixteen spoke connections are identical to each other, or in any
case are such as to form a balanced set, even with very low values,
for example 1 or 2 grams, of reduction in mass in the spoke
connection 7405r.
[0193] A reduction in mass of the spoke connection 7405r can be
provided in various ways, first of which is to make all of the
spokes cylindrical, but with different diameters, like in the
following example.
Example 4
[0194] Let us consider a steel cylindrical spoke 7505r with a
diameter of 2 millimeters, the spokes of the remaining spoke
connections 7401r-7404r, 7406r-7408r, 7401l-7408l on the other hand
being cylindrical and made of steel with a diameter of 2.3
millimeters.
[0195] Considering a length of the spokes of 286 millimeters,
whereas the spoke of reduced mass 7505r has a weight of 7.2 grams,
the remaining spokes have a weight of 9.2 grams. Also considering
that the distance R9 is again substantially equal to half the
geometric radius R of the wheel (in fact, equal to half the length
of the spoke 7505r added to the radius of the hub 72), the
reduction in mass of 2 grams reduces the dynamic imbalance of the
wheel 71.
[0196] It should be noted that also steel spokes with a diameter of
2.3 millimeters are commonly used in the field, for low range
wheels or on mountain bikes where economic considerations prevail
over the need to keep the weight of the wheel low.
[0197] To avoid the need to make spoke attachment seats 131 in the
rim 73 with two sizes, the spoke of the spoke connection 7405r
could have end portions with a diameter equal to the remaining
spokes, for example 2.3 millimeters and an intermediate portion
with a reduced diameter, for example 2 millimeters. A spoke having
an intermediate portion 155 with reduced diameter is illustrated in
FIG. 14.
[0198] Although the intermediate portion 155 with a reduced
diameter of the spoke illustrated in FIG. 14 is centered, it could
also be decentered towards the rim attachment side, to increase the
distance R9 from the center of mass of the mass reduction m9.
Moreover, the intermediate portion 155 with reduced diameter can be
flattened to make the spoke more aerodynamic.
[0199] A wheel 81 according to an eighth embodiment of the
invention, represented in FIG. 15, differs from the wheel 71 of
FIG. 13 in that both of the spoke connections 8405r and 8405l
adjacent the zone 832 of the joint are of reduced mass with respect
to the remaining spoke connections 8401r-8404r, 8406r-8408r,
8401l-8404l and 8406l-8408l. The spoke connections 8405r and 8405l
are also shown darkened merely for illustrative purposes. Also in
this case, sub-sets of spoke connections, for example the
connections 8401l-8408l, could have a different mass ms' than the
mass ms, and even equal to the mass of either or both spoke
connections 8405r and 8405l.
[0200] The resultant of the forces acting in the wheel 81 under
dynamic conditions is expressed by the following formula (11):
F=F1+F2+F10+F11 (11)
[0201] wherein the forces F10 and F11, which are the effect of the
reduced mass of the spoke connections 8405r and 8405l, are directed
inwards, with module m10*.omega..sup.2*R10 and
m11*.omega..sup.2*R11, and the remaining symbols are as described
above with reference to the first embodiment.
[0202] Also in the case of the wheel 81, it is possible to reduce
the dynamic imbalance with respect to a wheel in which all of the
sixteen spoke connections are identical to each other, or in any
case are such as to form a balanced set, even with very low values,
for example 1 or 2 grams, of reduction in mass in the spoke
connections 8405r and 8405l and, with a suitably selected value of
such reductions in mass, to eliminate such an imbalance, as
illustrated in the following example.
Example 5
[0203] Let us consider a mass of the zone 832 of the joint of 8.5
grams and a mass of the valve 7 of 6 grams.
[0204] A reduction in mass of 2.5 grams of the spokes of each of
the spoke connections 8405r and 8405l allows a wheel 81 that is
substantially dynamically balanced to be obtained.
[0205] In all of the above embodiments, the increase in mass or the
reduction in mass can be obtained, as stated, through a spoke with
an intermediate portion of greater cross-section 154 or smaller
cross-section 155 decentered towards the outer threading for
attachment to the rim, with the advantage of increasing the
distance of the center of mass of such a greater or smaller mass
from the rotation axis of the wheel and therefore of reducing the
necessary value of the mass itself.
[0206] An alternative, applicable in all of the embodiments of the
invention, consists of differentiating, instead of the mass of the
spoke of the spoke connections involved, the masses of their
removable connection element 6, in other words differentiating the
masses of the internally threaded element or nipple 61 and/or of
the plate 62 and/or providing the plate 62 only in the spoke
connections of increased mass.
[0207] Also in these cases, the difference in mass can be obtained
using two different types of material, for example aluminum and
brass or steel, or else using different sizes of elements 61, 62 of
the same material.
[0208] It should be noted that in this case the center of mass of
the additional or reduced mass is at a distance from the rotation
axis of the wheel substantially equal to the geometric radius of
the wheel itself (in fact, equal to the length of the spoke added
to the radius of the hub), and therefore additional or reduced
masses are necessary that are about half those required in the case
of differentiation of the spokes, as exemplified by the following
example.
Example 6
[0209] Under the conditions of example 2, the spokes of the spoke
connections 2401r and 2401l are replaced with spokes identical to
the spokes of the remaining spoke connections 2402r-2408r and
202l-2408l. The use of two removable connection elements 2601r and
2601l with a mass 1.25 grams more than the mass of the remaining
removable connection elements 2602r-2608r and 2602l-2608l leads to
the dynamic balance of the wheel.
[0210] A wheel 91 according to a ninth embodiment of the invention,
in particular a rear wheel, is represented in FIG. 16.
[0211] The spoke pattern of the wheel 91 has spoke connections that
are distributed equally spaced apart along the circumference of the
rim 93, even if they are crossed in triplets close to the hub
92.
[0212] The spoke pattern of the wheel 91 includes an odd number of
spoke connections, namely twenty-seven spoke connections, eighteen
spoke connections 9401r-9418r on the right hand side of the hub 92
and nine spoke connections 9401l-9409l on the left hand side of the
hub 92.
[0213] The hole 935 for the valve 7 is not diametrically opposite
the zone 932 of the joint, a position where there is one of the
seats 131 for a spoke connection 9418r. The hole 935 for the valve
7 is therefore at an angle of about 6.7.degree. (one fifty-fourth
of a revolution) with respect to the diameter D1 passing through
the zone 932 of the joint.
[0214] According to the invention, to reduce the dynamic imbalance
of the wheel 91 resulting from the localized masses m1 of the joint
932 and m2 of the valve 7, both of the spoke connections 9401r and
9418r adjacent to the hole 935 for the valve 7 are of increased
mass with respect to the remaining spoke connections 9402r-9417r
and 9401l-9409l. Also in FIG. 16, the connections of increased mass
are shown darkened merely for illustrative purposes.
[0215] The mass increase of each of the spoke connections of
increased mass 9401r and 9418r shall be selected of a suitable
value, not necessarily equal to each other, with reference to the
masses of the localized mass increases represented by the valve 7
and by the jointing zone 932, and also with reference to the masses
of the remaining spoke connections of the set, which could all be
the same or even of different values, for example different from
one side of the hub 92 to the other.
[0216] The resultant of the centrifugal forces acting in the wheel
91 under dynamic conditions can be expressed by the following
formula (12):
F=F1+F2+F12+F13 (12)
[0217] wherein
F12=m12*.omega..sup.2*R12 (13)
F13=m13*.omega..sup.2*R13 (14)
[0218] wherein R12 and R13 stand for the distances from the center
of the wheel 91 to the centers of mass of the additional mass m12
of the increased spoke connection 9401r and of the additional mass
m13 of the increased spoke connection 9418r, respectively, and the
remaining symbols are as described above with reference to the
first embodiment.
[0219] In case the increased mass of the spoke connections 9401r
and 9418r is obtained by two spokes like the spoke shown in FIG. 6
or in FIG. 7, R12 and R13 are substantially equal to half the
geometric radius R of the wheel 91 (in fact, equal to half the
length of the spoke of spoke connection 9401r or 9418r added to the
radius of the hub 92).
[0220] It should be noted that the forces F12 and F13, which are
the effect of the additional masses m12 and m13 of the spoke
connections 9401r and 9418r with respect to the remaining spoke
connections, act in the radial direction. It should also be noted
that the forces F2, F12 and F13 form an angle of 6.7.degree., of
less than 20.degree. and of less than 6.7.degree., respectively,
with the diameter D1 passing through the zone 332 of the joint. The
various centrifugal forces F1, F2, F12, F13 thus act along four
different directions. The forces F12 and F13 also strictly speaking
lie in a plane parallel to the median plane of the wheel 91, but
this effect is totally negligible on the dynamic behavior of the
wheel 91.
[0221] Also in the case of the wheel 91, it is possible to reduce
the dynamic imbalance with respect to a wheel in which all of the
twenty-seven spoke connections are identical to each other, or in
any case are such as to form a balanced set, even with very low
values, for example 1 or 2 grams, of the additional masses of the
spoke connections 9401r and 9418r and, with suitably selected
values of such additional masses, to eliminate such an
imbalance.
[0222] A wheel 101 according to a tenth embodiment of the
invention, in particular a rear wheel, is represented in FIG.
17.
[0223] The spoke pattern of the wheel 101 includes an odd number of
spoke connections, namely twenty-seven spoke connections, eighteen
spoke connections 10401r-10418r on the right hand side of the hub
102 and nine spoke connections 10401l-10409l on the left hand side
of the hub 102. The spoke connections are grouped together in nine
triplets.
[0224] The hole 1035 for the valve 7 is not diametrically opposite
the zone 1032 of the joint, a position very close to where there is
one of the seats 131 for a spoke connection 10401r. The hole 1035
for the valve 7 is therefore at a small angle of about 4.degree.
with respect to the diameter D1 passing through the zone 1032 of
the joint.
[0225] According to the invention, to reduce the dynamic imbalance
of the wheel 101 resulting from the localized masses m1 of the
joint 1032 and m2 of the valve 7, the intermediate spoke connection
10401l of the triplet of spoke connections adjacent the hole 1035
for the valve 7 is of increased mass with respect to the remaining
spoke connections 10402l-10409l and 10401r-10418r. Also in FIG. 17,
the connection of increased mass 10401l is shown darkened merely
for illustrative purposes.
[0226] The spoke connection of increased mass 10401l is precisely
the one adjacent the spoke connection 10401r essentially
diametrically opposite the zone of the joint 1032, on the opposite
side with respect to the valve 7, so that the centrifugal force F14
due to its additional mass m14 with respect to the remaining spoke
connections, or at least with respect to the remaining spoke
connections of a regular sub-set of connections to which it
belongs, like for example the sub-set of spoke connections
10401l-10409l, has a component along the diameter D1 passing
through the zone of the joint 1032 and a component suitable for
partially compensating for the component perpendicular to the
direction D1 of the centrifugal force F2 due to the valve 7.
[0227] Also in the case of the wheel 101, it is possible to reduce
the dynamic imbalance with respect to a wheel in which all of the
twenty-seven spoke connections are identical to each other or in
any case are such as to form a balanced set, even with very low
values, for example 1 or 2 grams, of the additional mass of the
spoke connection 10401l and, with suitably selected values of such
an additional mass, to substantially eliminate such an
imbalance.
[0228] Although it is also possible to differentiate the masses of
the removable connection elements when these are provided at the
hub of the wheel instead of at the rim, such a solution is not
particularly advantageous since the distance from the rotation axis
would be very small and therefore a very large differentiation of
mass would be needed.
[0229] Of course, it is also possible to distribute the greater or
lesser mass between the spoke and the removable connection element
of the spoke connections involved, as well as to use spokes of
identical size, but made from two materials having different
specific densities, like steel and aluminum or brass and
aluminum.
[0230] In the previous embodiments the assumption that the mass m1
of the joint is greater than the mass m2 of the valve was always
considered, since this is the most common situation. Those skilled
in the art shall, however, understand that in case the mass m1 of
the joint is, on the other hand, lower than the mass m2 of the
valve, the solutions described up to now shall be applied mutatis
mutandis.
[0231] It should also be understood that the number of spoke
connections of increased or reduced mass need not be only one or
two. Just as an example, it is possible to combine the solutions of
the first and second embodiment, arranging spoke connections of
suitable increased mass 7405l, 7405r, 7406l in the wheel of the
first embodiment.
[0232] From reading the present description, those skilled in the
art shall understand that it is more generally possible to use, in
the case of single-piece rims like for example rims made from
composite material, any number of spoke connections of increased
mass, preferably but not necessarily the same as each other, in the
half of the rim opposite the one centered about the single
localized mass discontinuity or increase represented by the valve,
or else any number of spoke connections of reduced mass in the half
of the rim centered about the valve.
[0233] In the case of rims with jointing like for example metal
rims, it is in general possible to use any number of spoke
connections of increased mass in the half of the rim opposite the
half centered about the greatest localized mass increase (typically
the zone of the joint), or else any number of spoke connections of
reduced mass in the half of the rim centered about the greatest
localized mass increase.
[0234] In such a simple way it is possible to also at least
partially compensate for a second smaller localized mass increase,
typically the valve.
[0235] This occurs, in particular, when the second, smaller
localized mass increase is diametrically opposite, or substantially
opposite, with respect to the first and therefore the two localized
mass increases partially compensate for each other, like in the
illustrated embodiments.
[0236] However, it must be clear that the present invention is not
limited, in the case of rims with jointing like for example metal
rims, by the fact that the zone of the joint is diametrically
opposite, or substantially opposite, with respect to the valve.
Those skilled in the art will understand that in case such elements
are closer together it shall be sufficient to increase the mass of
the spoke connection(s) of increased mass, which shall be arranged
in a suitable position, for example in a position substantially
opposite an intermediate position between the joint and the valve,
or else to reduce the mass of the spoke connection(s) of reduced
mass, which shall be arranged in a suitable position, for example
in a position substantially adjacent to the joint.
[0237] It is also possible to provide for a separate compensation
of the localized mass discontinuities or increases represented by
the jointing zone and by the valve, for example providing for one
or two spoke connections of increased mass substantially opposite
the valve and one or two spoke connections of increased mass
substantially opposite the jointing zone, or else one or two spoke
connections of reduced mass substantially adjacent to the valve and
one or two spoke connections of reduced mass substantially adjacent
to the jointing zone, or else one or two connections of increased
mass substantially opposite the greatest localized mass increase of
the two and one or two connections of reduced mass substantially
adjacent to the smallest localized mass increase.
[0238] FIG. 18 represents a wheel 111, in particular a front wheel,
according to an eleventh embodiment of the invention.
[0239] The spoke pattern of the wheel 111 may be seen as including
a regular, balanced sub-pattern that includes sixteen spoke
connections 11401l-11408l, 11401r-11408r. According to the
invention, to reduce the dynamic imbalance of the wheel 111
resulting from the localized masses m1 of the joint 1132 and m2 of
the valve 7, it is provided to use an additional spoke connection
11409, shown darkened for illustrative purposes only.
[0240] It is noted that the positions of the overall set of spoke
connections 11401l-11408l, 11401r-11408r, 11409 are irregularly
arranged about the rotation axis of wheel 111.
[0241] The hole 1135 for the valve 7 is not diametrically opposite
the zone 1132 of the joint, although in such an opposite position
there is none of the seats 131 for the spoke connections. The hole
1135 for the valve 7 is instead at a small angle of about
3.75.degree. with respect to the diameter D1 passing through the
zone 1132 of the joint.
[0242] The additional spoke connection 11409 is adjacent the
position diametrically opposite the zone of the joint 1132, on the
opposite side with respect to the valve 7, and at a same angle of
3.75.degree. with diameter D1.
[0243] The resultant of the centrifugal forces acting in the wheel
111 under dynamic conditions can be expressed by the following
formula (15):
F=F1+F2+F15 (15)
[0244] wherein:
F15=m15*.omega..sup.2*R15 (16)
[0245] wherein R15 stands for the distance from the center of the
wheel 111 to the center of mass of the mass m15 of the additional
spoke connection 11409, and the remaining symbols are as described
above.
[0246] It should be noted that R15 is substantially equal to half
the geometric radius R of the wheel 111, actually equal to half the
length of the additional spoke 11409 added to the radius of the hub
112.
[0247] Furthermore, it is to be noted that the centrifugal force
F15 has a component along the diameter D1 passing through the zone
of the joint 1132 and a component suitable for at least partially
compensating for the component perpendicular to the direction D1 of
the centrifugal force F2 due to the valve 7.
[0248] With proper values of the mass m15 of the additional spoke
11409, the value of the resultant of the forces F gets close to
zero and the dynamic imbalance of the wheel 111 reduces with
respect to a wheel in which there are only the sixteen spoke
connections 11401l-11408l, 11401r-11408r identical to each other or
in any case such as to form a balanced set.
[0249] It will be noted that the set of spoke connections of wheel
111 is imbalanced, but once it is connected in the wheel between
the hub 112 and the rim 113, and once the valve 7 has been fitted,
the wheel 111 is less imbalanced, if not perfectly balanced.
[0250] Preferably, the additional spoke connection 11409 will be
identical to the other spoke connections 11401l-11408l of the left
side of the hub and/or to the other spoke connections 11401r-11408r
of the right side of the hub. This obviates the need to manufacture
special spoke connections, in particular special spokes, and/or to
drill different spoke attachment seats 131 in rim 113.
[0251] Mass m3 of the additional spoke connection 11409 may however
also be different from the mass of the other spoke connections
11401l-1408l of the left side of the hub and/or of the other spoke
connections 11401r-11408r of the right side of the hub.
[0252] An additional spoke connection 11409 of different mass may
be obtained in any of the numerous ways outlined above.
[0253] In particular, when at least part of the additional spoke
connection 11409 is made of plastics, the additional spoke
connection 11409 will be lighter than spokes 11401l-11408l,
11401r-11408r of the balanced sub-set made of metal.
[0254] Preferably, moreover, the additional spoke connection 11409
will not be tensioned, so that the wheel 111 will still be balanced
from a static point of view.
[0255] FIG. 19 represents a wheel 141, in particular a front wheel,
according to a twelfth embodiment of the invention.
[0256] The spoke pattern of the wheel 141 may again be seen as
including a regular, balanced sub-pattern that includes sixteen
spoke connections 14401l-14408l, 14401r-14408r. According to the
invention, to reduce the dynamic imbalance of the wheel 141 due to
the localized masses m1 of the joint 1432 and m2 of the valve 7, it
is provided to use two additional spoke connections 14409l and
14409r, shown darkened for illustrative purposes only.
[0257] In the wheel 141, the hole 1435 for the valve 7 is
diametrically opposite the zone 1432 of the joint.
[0258] The additional spoke connections 14409l and 14409r are
adjacent the hole 1435 for the valve 7, on opposite sides thereof
with respect to the valve 7.
[0259] The resultant of the centrifugal forces acting in the wheel
141 under dynamic conditions can be expressed by the following
formula (17):
F=F1+F2+F16+F17 (17)
[0260] wherein
F16=m16*.omega..sup.2*R16 (18)
F17=m17*.omega..sup.2*R17 (19)
[0261] wherein R16 and R17 stand for the distances from the center
of the wheel 141 to the centers of mass of the mass m16 of the
additional spoke connection 14409l and of the mass m17 of the
additional spoke connection 14409r, respectively, and the remaining
symbols are as described above.
[0262] It should be noted that the forces F16 and F17 each form an
angle of 3.75.degree. with the diameter D extending between the
zone of the joint 1432 and the valve 7, the diameter along which
the forces F1 and F2 act, in opposite directions. The resultant of
the two forces F16 and F17 therefore acts along the diameter D. The
forces F16 and F17 also strictly speaking lie in planes parallel to
the median plane of the wheel 141, but on opposite sides, and their
effect is totally negligible on the dynamic behavior of the wheel
21.
[0263] With proper values of the additional mass m16 and m17, the
dynamic imbalance of the wheel 141 is reduced with respect to a
wheel in which there are only the sixteen spoke connections
14401l-14408l, 14401r-14408r identical to each other or in any case
such as to form a balanced set.
[0264] The imbalance resulting from the presence of the sleeve 133
or other type of joint and of the valve 7 can in such a case be
totally cancelled out with a suitable selection of values m16 and
m17, obtaining perfect balance.
[0265] It will be noted that also the set of spoke connections of
wheel 141 is imbalanced, but once it is connected in the wheel
between the hub 142 and the rim 143, and once the valve 7 has been
fitted, the wheel 141 is less imbalanced, if not perfectly
balanced.
[0266] Also in this case, the additional spoke connections 11409l
and 11409r will preferably be identical to the other sixteen spoke
connections, to avoid the need for special manufacture, and not
tensioned, so that the wheel 141 will still be balanced from a
static point of view.
[0267] It will be understood that an unbalanced set of spoke
connections, that will dynamically balance the wheel once mounted
and fitted with valve 7, may be obtained by additional spoke
connections like in the eleventh and twelfth embodiments also in
different spoke patterns, such as in spoke patterns that include an
odd number of spoke connections as shown e.g. in FIG. 10 and FIG.
11; in spoke patterns that include groups of spokes, such as
triplets, irrespectively of the number of spoke connections, as
shown in FIG. 12 or in FIG. 17; in rims made of composite material,
thus lacking a joint, like those shown in FIG. 11 and in FIG.
12.
[0268] It will further be understood that the number of additional
spoke connections need not be only one or two, and that they need
not be arranged in the same intraspoke zone as the valve or, more
in general, as the lightest mass increase. Instead, the additional
spoke connection(s) may be arranged in intraspoke zone(s) adjacent
the intraspoke zone containing the lightest localized mass
increase.
[0269] In the case of rims with jointing like for example metal
rims, it is in general possible to use any number of additional
spoke connections in the half of the rim opposite the half centered
about the greatest localized mass increase (typically the zone of
the joint).
[0270] When the zone of the joint is not diametrically opposite, or
substantially opposite, with respect to the valve, a suitable
number of additional spoke connection(s) of a suitable mass shall
be arranged in a suitable position, for example in a position
substantially opposite an intermediate position between the joint
and the valve.
[0271] It is also possible to provide for a separate compensation
of the localized mass discontinuities or increases represented by
the jointing zone and by the valve, for example providing for one
or two additional spoke connections substantially opposite the
valve and one or two additional spoke connections substantially
opposite the jointing zone.
[0272] Like in the case of the spoke connections of increased mass,
in the case of single-piece rims like for example rims made from
composite material, it will be possible to use any number of
additional spoke connections, preferably but not necessarily of the
same mass, in the half of the rim opposite the one centered about
the single localized mass discontinuity or increase represented by
the valve.
[0273] Finally, while it is preferred to retain a subset of spoke
connections that is balanced with respect to the axis of rotation
of the wheel to easily obtain balance from a static point of view
by not tensioning the additional spoke connection(s), those skilled
in the art will understand that this is not mandatory within the
invention. Indeed, it will be possible to devise a number of other
spoke patterns that are so imbalanced as to cause perfect balance
of the wheel once the valve is fitted, and that also perform well
from a static point of view.
[0274] The set will include denser regions, i.e. with a greater
number of spoke connections, and less dense regions, i.e. with a
smaller number of spoke connections, the criteria for their
arrangement with respect to the localized mass increase(s) of the
wheel being analogous to the criteria outlined above for arranging
spoke connection(s) of a different mass within a regular sub-set of
spoke connections of the wheel.
* * * * *