AERODYNAMIC SPOKE FOR SPOKED WHEELS, ESPECIALLY FOR BICYCLES

Description

Aerodynamic spoke for spoked wheels, especially for bicycles DESCRIPTION The present invention relates to an aerodynamic spoke for spoked wheels, in particular for bicycles, according to the preamble of claim 1. A spoke 5 including such features is known for example from DE202004001185U1. The document proposes to create spokes with improved aerodynamics due to the presence of imprints on the stem that form a plurality of micro-recesses similar to those present on the surface of golf balls. In an alternative embodiment the imprints are elongated in the longitudinal direction of the stem or arranged in 10 spiral. The document claims that the presence of such repeated geometric formations helps to reduce the aerodynamic resistance of the spoke during rotation of the spoked wheel. Another ray is known from CN202863011(U). This paper proposes a ray provided with repeated widenings in step with which the reflective surface is increased 15 of the spoke to improve the visibility of the wheel at night. The document has no However, it is related to aerodynamic effects and is actually a counterproductive suggestion in this respect. The present invention fits into this technological direction and aims to further improve the aerodynamics of the spoke. The technical problem addressed and 20 solved by the invention is therefore to provide a spoke for wheels spoked, especially for bicycles, structurally and functionally designed for obtain a further reduced aerodynamic resistance compared to what achievable through the teachings of the aforementioned prior art. In the context of this problem it is an object of the invention to make available a beam in 25 where the improved aerodynamics does not compromise its mechanical resistance of the radius. Another aim is to provide a radius whose realization is possible without substantially altering the production cycle. This problem is solved and these and other goals are achieved through a ray aerodynamic for spoked wheels, especially for bicycles, made in accordance with 5 at least some of the characteristics which are the subject of the attached claims. In a preferred embodiment an aerodynamic spoke comprises a stem elongated in a dominant longitudinal direction and means on the surface of said stem to reduce the aerodynamic resistance of the spoke. Preferably the means the aforesaid comprise a plurality of undulations on the surface of said stem with 10 crests and valleys extending transversely to the said dominant longitudinal direction. Considering simultaneously each of the sections of the stem orthogonal to the dominant longitudinal direction of the stem itself it is possible to identify a theoretical nominal average section that deviates least from each of the sections considered. By analyzing each of the sections of the stem it is therefore possible to define 15 as a crest any portion of the affected section that extends outside of the area identified by the said nominal average section; it can instead be defined as a valley any area of ​​space devoid of material identified by the difference between a given section of the stem and called nominal average section. They will be supplied in following are explanatory, but not limiting, examples for the definition of crests and valleys 20 in some of the possible embodiments of the aerodynamic radius. It is understood that, in the case of other particularly complex ray shapes, a expert technician in the field, thanks to the definition above and the examples that will be provided, would be able to identify the theoretical nominal average section and, consequently, any crests and valleys that may be present on the radius in question. 25 According to a preferred aspect of the invention the consecutive crests and / or valleys are between they are spaced at a smaller step than the largest transverse dimension of the stem orthogonal to the longitudinal dimension of the stem itself. This It involves a high number of ridges and valleys arranged closely together on the surface of the stem. 5 According to an important aspect of the invention, the corrugations comprise crests and continuously extending valleys between opposite longitudinal sides of the radius In accordance with a preferred solution the spoke stem has a cross-section flattened, preferably substantially elliptical. In another preferred embodiment the spoke shaft has a cross-section 10 flattened, preferably substantially rectangular. Preferably, these crests and valleys are parallel to each other. Preferably the direction of greatest extension of each of said crests and valleys forms, with the longitudinal direction of the stem, an angle between 45° and 95°, and preferably equal to 90° + / - 5°. 15 According to an important aspect of the invention, the aerodynamic radius has at the longitudinally opposite ends of the respective means of fastening to a hub and a wheel rim. Preferably said undulations are terminated by a distance of 10-50mm from said respective fixing means. According to a further preferable aspect of the invention, the corrugations have 20 of the alternations of said crests and valleys on opposing surfaces of the stem and, preferably, said alternations on opposite surfaces of the stem are among themselves symmetrical. Preferably the maximum depth of the corrugations is between 0.1 and 1 mm, where depth means the difference in elevation from the stem axis between a 25 ridge and a valley. The features and advantages of the invention will be better understood from the description. detailed description of two of his favorite, but not exclusive, examples of his realization illustrated for indicative and non-limiting purposes with reference to the attached drawings in which: - Fig. 1 represents an overall perspective view of a first form of 5 realization of the invention - Fig. 2 represents a plan view of the first embodiment of the found - Fig. 3 represents a partial perspective view of a detail of the first embodiment of the invention 10 - Fig. 4a represents a lateral orthogonal view of a portion of the first embodiment of the invention - Fig. 4b represents a lateral orthogonal view of a portion of a second embodiment of the invention - Fig. 5 shows a partial sectional view of fig. 4a made using the 15th floor V - V - Fig. 6 shows a sectional view of fig. 4a taken using plane VI – VI - Fig. 7 shows a sectional view of fig. 4a taken using plane VII – VII 20 In the figures, 1 indicates a total radius for a spoked wheel, for example for example a bicycle wheel or similar. The spoke 1 comprises a stem 2, with a predominantly longitudinal extension, i.e. in which the longitudinal dimension is dominant and largely exceeds the thickness and the transverse extension of the stem. The stem 2 has an elongated portion 3 25 preferably with a flattened section, for example elliptical, with opposing surfaces 4, 5 and opposite longitudinal sides 6, 7. The elongated portion 3 is preferably terminated at both ends longitudinal with a cylindrical section 12 carrying fixing means respectively a traditional wheel rim and wheel hub in themselves. Typically such means 5 fixings may include an enlarged brim 8 and a threaded section 9 for the engagement of an unillustrated nipple. The stem 2 may comprise two or more contiguous elongated portions 3 even if the the provision of a single elongated portion 3 is preferable. In the embodiments shown here, the cylindrical sections 12 are connected to the 10 elongated portion 3 by means of two substantially truncated cone-shaped connections 13; However, in other embodiments not illustrated, said fittings 13 could not be present. On at least one of the opposing surfaces 4, 5 of the elongated portion 3, and preferably on both, means are provided to reduce the resistance 15 aerodynamics of the beam, which include, in a preferred solution of the invention, a plurality of undulations on the surface of said stem with ridges 10 and valleys 11 extending transversely to the said dominant longitudinal direction. Preferably crests and valleys 10, 11 are continuous or extend without interruptions between the opposite longitudinal sides 6, 7 of radius 1. Ridges and valleys are also 20 preferably parallel to each other and approximately perpendicular to the sides longitudinal 6, 7 of the radius. The pattern of the undulations is intended to include an orientation of the extension greater than each of said crests and valleys 10,11 with respect to the longitudinal direction of an angle between 45° and 95°, where said angle can be evaluated in an axial direction 25 clockwise or counterclockwise. Preferably, the orientation is 90°, plus or minus 5°, with respect to the longitudinal direction of the beam. Preferably the depth of the undulations, understood as the difference in elevation from the axis of the stem between a crest and a valley, is of the order of 1 mm; a value further preferable is of the order of 0.1 mm. The corrugations, moreover, are 5 preferably terminated at a distance of 10-50mmm from the respective means of fixing 8, 9. As can be seen from fig. 4a and 4b, in the first two embodiments illustrated, the undulations present alternating crests and valleys 10, 11 on both sides opposing surfaces 4, 5, furthermore said alternations of crests and valleys are found among themselves 10 symmetrical; however, in other embodiments not reported, said alternations they may not be symmetrical to each other, or the undulations may present an alternation of crests and valleys even on only one of the two surfaces opposing 4, 5. Always referring to fig. 4a and 4b, it can be noted how the said crests and valleys 15 10, 11 can be obtained on the said radius 1 in different ways: - in the first embodiment illustrated in fig. 4a the elongated portion 3 It has an initial diameter D1, adjacent to the connection 13, from which the following are obtained: for relief the crests 10, while the valleys 11 are thus defined in a way indirect; 20 - in the second embodiment illustrated in fig. 4b the elongated portion 3 has an initial diameter D2, adjacent to the connection 13, from which are the valleys 11 are obtained by constriction, while the crests are thus defined in indirect way. In both cases mentioned above the spoke has a reduced aerodynamic resistance. 25 following the rotation of the spoked wheel on which it is mounted with respect to elliptical spokes in which the surfaces 4,5 are free of undulations. In figs. 5, 6, and 7, schematic and partial sections of the first are shown. illustrated embodiment of the aerodynamic beam 1, suitable to exemplify the definition of any crests and valleys 10, 11 starting from the identification of the theoretical 5 nominal medium section M. It is believed that the examples given in Figs. 5 to 7 will allow an expert in the branch of identifying any crests and valleys in a wide range of embodiments, even complex ones, for the aerodynamic radius 1 which is the subject of this patent.

Claims

1. Aerodynamic spoke (1) for spoked wheels, in particular for bicycles, comprising a stem (2) elongated in a dominant direction and means on the surface of said stem for decreasing the aerodynamic drag of the spoke, characterised in that said means comprise a plurality of undulations on at least a portion of the surface of said stem with crests (10) and valleys (11) extending transversely to said dominant direction.

2. Aerodynamic spoke (1) according to claim 1, wherein said stem (2) defines a major transverse dimension orthogonal to said dominant direction, and where consecutive crests and / or valleys (10, 11) are spaced from each other with a smaller pitch than said major transverse dimension.

3. Aerodynamic spoke (1) according to one or more of the preceding claims, where crests (10) and valleys (11) are continuous between opposing longitudinal sides (6, 7) of the spoke.

4. Aerodynamic spoke (1) according to one or more of the preceding claims, where the stem (2) of the spoke has a flattened cross-section.

5. Aerodynamic spoke (1) according to claim 4, where the stem (2) of the spoke has a substantially elliptical cross-section.

6. Aerodynamic radius (1) according to one or more of the preceding claims, where said crests (10) and valleys (11) are parallel to each other.

7. Aerodynamic spoke (1) according to one or more of the preceding claims, where the direction of greatest extension of each of said crests (10) and valleys (11) forms, with the longitudinal direction of the stem (2), an angle between 45° and 95° 8. Aerodynamic radius (1) according to claim 7, wherein said angle is equal to 90° + / - 5°.

9. Aerodynamic spoke (1) according to one or more of the preceding claims, having at the longitudinally opposite ends respective means 5 for fixing to a hub and to a wheel rim.

10. Aerodynamic spoke (1) according to claim 9, wherein the corrugations are terminated at a distance of 10-50mm from the respective fixing means (8, 9).

11. Aerodynamic spoke (1) according to one or more of the preceding claims, wherein the undulations present alternations of said crests (10) and valleys (11) 10 on opposite surfaces (4, 5) of the stem (2).

12. Aerodynamic spoke (1) according to claim 11, wherein the alternations of crests (10) and valleys (11) on opposing surfaces (4, 5) of the stem (2) are symmetrical to each other.

13. Aerodynamic beam (1) according to one or more of the preceding claims, wherein the maximum depth of the corrugations is between 0.1 and 1 mm.