The present invention relates to a device for mounting a spoke on a wheel rim or hub.
It applies more particularly to the wheels of a bicycle.
The mounting of a spoke on a wheel rim is generally carried out using a nut traversing the wheel rim and screwed around the spoke. This mounting creates a tension in the spoke, and one obtains an assembled wheel of quality when the tension is uniform in all the spokes assembled on the rim. The spoke/nut connection can also be carried out on the level of the hub of wheel.
However, it is known that in such an assembly, the wheel thus assembled receives sudden lateral shocks and forces, which causes the relaxation of the effected spokes and the loosening of the nuts and has as a consequence the appearance of effects known as “sail” and “jump” on the effected wheel. These loosening effects appear more particularly on the rear wheels of a bicycle which have less tightened spokes on the side opposed to the free wheel. These loosening effects thus appear more frequently on the side opposite to that where the pinions are mounted.
To solve these problems of relaxation of the spokes and loosening of the nuts relative to the spokes, various solutions have already been proposed.
There is first of all, the solutions of the handcrafted type specific to each assembler of wheels who uses, according to their experience and the means available, the glue, various resins, tallow . . . .
Some have tried to develop industrial solutions directly at the time of the manufacture of the wheel.
Thus, it is known to stick the nut on the spoke with anaerobic adhesive such as that sold under mark “LOCTITE”. This solution is of a high cost and not very reliable because the polymerization of the adhesive is random and a possible later tension adjustment shears the adhesive and the risk of loosening reappears.
U.S. Pat. No. 6,205,664 shows a nut whose head holds a plastic ring which brakes the threaded end of the spoke screwed in to the nut. This solution is reliable but of a high cost because delicate to effectuate.
U.S. Pat. No. 6,557,946 shows a nut for a spoke in which an encapsulated adhesive is placed in the part opposite to the head and which also brakes the threaded end of the spoke screwed in to the nut. This solution is also of a very high cost, which leaves it applicable to the top-of-the-line wheels. Moreover as the solution of joining seen above, it does not allow multiples readjustment without shearing of the adhesive.
Lastly, patent FR2801247 shows a nut deformed locally by a punch, which locally crushes at the same time the thread of the nut and that of the rod of spoke. This solution is not reliable because the local deformation is too weak to obtain a satisfactory braking in the tolerance range of thread screw/nut thread.
The goal of the invention is then to propose another particularly simple, reliable and not very expensive solution.
To this end, the invention has as an object a device for mounting a spoke on a rim of wheel, of the type including a spoke including a rod which extends along an axis (X-X′) and whose end is provided with an external threading screwed into the internal threads of a nut, mounted in an opening defined interior to the rim, characterized in that at least a part of the threaded end of the spoke, screwed in to the nut, is curved relative to axis (X-X′), in order to increase the braking torque by direct friction of the nut by connection to the rod.
The general problems of the braking of a spoke nut relative to the spoke are in particular related to the fact that threads are of very small dimension and that the standardized tolerance between the screw and the nut is relatively wide compared to the nominal dimension of threads. Thus for a thread diameter of 2.25 mm and a thread on the order of 0.45 mm, the extent of the play is approximately 0.15 mm, and consequently, to obtain a relatively constant braking torque in all these tolerance cases, it is necessary to have a deformable element which compensates for the variations of play of this screw/nut adjustment.
The idea of the patent is to use the spoke itself as deformable element by making it work in a bent state inside the nut itself. Thus, one does not add an additional element. The bending of the spoke generates stress of radial contact between the screw and the nut and induces a tangent component by friction thus generating a braking torque that one seeks to their rotational displacement.
Other characteristics and advantages of the invention will emerge from the description which will follow relative to the annexed drawings which are given only by way of nonlimiting examples.
a is also a longitudinal cross-sectional view of a mounting device according to the embodiment of
The mounting of the spoke (1) in the nut (2) according to the invention is illustrated in the various figures with play between the nut and the spoke intentionally exaggerated to facilitate the understanding of the invention.
According to the illustrated embodiment, the device according to the invention for mounting a spoke (1) on a wheel rim is of the type including a spoke (1) made up of a rod (10) which extends according to an axis (X-X′) and whose end (11) is provided with an external thread (110) screwed into the internal threads (200) of a nut (2), mounted in an opening defined inside the rim.
According to the invention, at least a part (11a, 11b, 11c, 11d, 11e, 11f) of the threaded end (11) of the spoke (1), screwed in the nut (2), is curved relative to axis (X-X′) in order to increase the braking torque by direct friction of the nut (2) relative to the rod (10).
According to the preferred embodiment of
According to the alternative embodiments of
As mentioned previously, the play between the spoke (1) and the nut (2), as shown in
According to embodiments illustrated to the
According to the illustrated embodiment of
According to the embodiment illustrate with
According to the embodiment illustrated in
According to the embodiment illustrated in
According to the preferred manufacturing process of the spoke (1) according to the invention, the spoke (1) is curved by introduction into the space defined by the two stamping elements (3a, 3b) of form separated one of the other (
The invention which has been just described allows a simple, reliable and inexpensive mounting of a nut on a wheel spoke of a bicycle. Thus, the braking torque according to the invention is controlled precisely and stablely to any tolerances of fit between the spoke and the nut.
One obtained very good braking results in an embodiment of a spoke with threads of 2.25 mm diameter according to
It can be advantageous to exaggerate the deflection or off-set of the spoke, because, in this case, at the time of the first screwing in, the spoke will be engaged by the nut which will plastically limit its off-set: thus if one unscrews a spoke which had been screwed in completely beforehand, one notes that its off-set will have decreased. In other words, it will have been unbent to adapt to the maximum of its deformation capability in inflection relative to the nut and their relative play, thus gauging the braking torque more precisely by plastic deformation. The use of multiple waves, as shown the
In a general way, it is preferable that the first threads engage between the nut and the spoke exactly rectilinear or not deformed, because those are these first threads which most sought: it is thus preferable to begin the curving of the spoke right after this zone so as not to risk weakening the strength of the first threads of the spoke (see
The invention can apply perfectly to the already existing wheels whose the spokes can be dismounted and bent locally on the level of the threaded part of the rod, for example using a bending apparatus envisaged for this purpose, before being again screwed in individually in their associated nut.
Of course, the invention is not limited to the embodiments described and represented by way of the examples, but it includes also all the technical equivalents and their combinations.
For example, it is possible to envisage a spoke curved before its screwing in the nut, and to envisage a nut with an additional means of bending of the same part or another part of the threaded rod, inside the housing of the nut.
|05 01836||Feb 2005||FR||national|
|Filing Document||Filing Date||Country||Kind||371c Date|
|Publishing Document||Publishing Date||Country||Kind|
|3087525||Nyswaner et al.||Apr 1963||A|
|6210091||Ono et al.||Apr 2001||B1|
|6557946||Gerrit et al.||May 2003||B1|
|0 123 519||Oct 1984||EP|
|0 838 352||Apr 1998||EP|
|2 801 247||May 2001||FR|
|WO 2004065138||Aug 2004||WO|
|20090050276 A1||Feb 2009||US|