ROTARY POWER TRANSMISSION UNIT FOR BICYCLE RIDING

Abstract

A rotational force transmission element (1) for steering a bicycle (10), in particular a stem (6) or a crank arm (7, 8), comprising a centrally hollow, elongated body (2) situated between two extreme attachment zones (4), one with a steering interface element, in particular a handlebar or a pedal, the other with the corresponding part of the bicycle, the volumetric void ratio being greater than or equal to 25%, and more preferably greater than or equal to 30%, and even more preferably greater than or equal to 35%. FIGURE 2

Description

Title of the invention: ROTARY POWER TRANSMISSION DEVICE FOR BICYCLE RIDING technical field

[0001] The present invention relates to a rotational force transmission element for steering a bicycle, in particular a stem or a crank arm, comprising an elongated, centrally hollow body situated between two extreme attachment points, one with a steering interface element, in particular a handlebar or a pedal, and the other with the corresponding part of the bicycle. The invention also relates to a bicycle equipped with one or the other of these elements. Previous technique

[0002] Bicycle performance is directly related to its mass. In a constant quest to improve this performance, significant developments have been made in recent years to optimize the various components of the bicycle, particularly with regard to their mass. Efforts have focused on the use of lighter materials, new designs, or simply on optimizing conventional parts.

[0003] For example, US patent 5904072 describes a crankset comprising a crank arm for attachment to the chainrings by a system having a plurality of mounting tabs. The crank arm also has a longitudinal groove designed to lighten the assembly.

[0004] Document FR2973769 describes a bicycle stem made of lightweight material, in particular a composite material.

[0005] These components allow for some mass savings, although these are not fully optimized.

[0006] There is therefore still a need to design high-performance bicycle components, particularly with minimal mass, without sacrificing endurance and mechanical strength characteristics. Summary of the invention

[0007] First of all, a first objective of the invention is to provide one or more bicycle parts enabling the creation of a high-performance bicycle with a reduced mass.

[0008] Yet another objective of the invention is to provide one or more bicycle parts enabling the production of a high-performance bicycle without degradation of the characteristics of endurance, resistance and solidity.

[0009] To achieve this, the invention provides a rotational force transmission element for steering of a bicycle, in particular a stem or a bottom bracket arm, comprising an elongated centrally hollowed body situated between two extreme attachment zones, one with a steering interface element, in particular a handlebar or a pedal, the other with the corresponding part of the bicycle, the volumetric void ratio being greater than or equal to 25%, and more preferably greater than or equal to 30% and even more preferably greater than or equal to 35%.

[0010] Such an architecture is advantageously used to equip high-performance bicycles, particularly racing and / or competition bicycles. The weight savings achieved compared to conventional parts make it possible to produce lighter bicycles without compromising strength, durability, or robustness. Cyclists or racers using such bicycles can thus increase their potential performance level.

[0011] According to an advantageous embodiment, the elongated body comprises at least one portion consisting of a lattice structure. Such a structure allows for significant mass reductions.

[0012] Advantageously, the surface void ratio of such a structure is greater than or equal to 25%, and more preferably greater than or equal to 30% and even more preferably greater than or equal to 40%.

[0013] According to an advantageous embodiment, at least one fixing zone cooperates with the truss structure. Tests have shown that a fixing zone combined with a truss structure allows for mass reductions without degrading the strength, durability, or robustness characteristics.

[0014] According to an advantageous embodiment, the force transmission element consists of a bracket. In such a case, it is advantageous to provide that the entire body is made up of a truss structure.

[0015] According to another advantageous embodiment, the force transmission element consists of a crank arm on the side of the chainring(s). In such a case, it is advantageously provided that the area for attaching to the chainrings comprises a plurality of mounting tabs.

[0016] The invention also provides for a bicycle comprising a rotational force transmission element for driving as previously described. Brief description of the drawings

[0017] All implementation details are given in the following description, supplemented by Figures 1 to 13, presented solely for the purpose of non-limiting examples, and in which: Fig. 1

[0018] [fig.1] Figure 1 is a representation of an example of a gallows of the art previous, shown in perspective; Fig. 2

[0019] [fig.2] Figure 2 is a perspective representation of an example of a gallows; Fig.3

[0020] [fig.3] Figure 3 is a top view of the gallows of Figure 2; Fig. 4

[0021] [fig.4] Figure 4 is a front view of the gallows of Figure 2; Fig. 5

[0022] [fig.5] Figure 5 is a representation of an example of a crank arm (side trays) of earlier art, shown in perspective; Fig. 6

[0023] [fig.6] Figure 6 is a front view of an example of a crank arm (side trays); Fig. 7

[0024] [fig.7] Figure 7 is a perspective view of the crank arm of Figure 6; Fig. 8

[0025] [fig.8] Figure 8 is a side view of the crank arm of Figure 6; Fig. 9

[0026] [fig.9] Figure 9 is a representation of an example of a crank arm (side as opposed to the plateaus) of earlier art, shown in perspective; Fig. 10

[0027] [fig.10] Figure 10 is a perspective view of an example of a crank arm (opposite side of the plateaus); Fig. II

[0028] [fig.l 1] Figure 11 is a side view of the crank arm of Figure 10; Fig. 12

[0029] [fig.12] Figure 12 illustrates an example of a crankset using the arms of figures 6 and 10; Fig. 13

[0030] [fig.13] Figure 13 illustrates an example of a bicycle using transmission components of effort by rotation for driving. Description of the implementation methods DEFINITIONS

[0031] By "volumetric void ratio" is meant the proportion of the total volume of the part occupied by void space. This proportion is established on the basis of a virtual solid part, occupying an identical total volume, with an identical shape.

[0032] By "surface void ratio" is meant the proportion of the external surface of the part occupied by void. This proportion is established on the basis of a solid virtual part, occupying an identical volumetric envelope, with an identical shape and a solid surface.

[0033] By “truss structure” is meant a mechanical arrangement formed by a plurality of beams cooperating with each other and forming a structure with at least as many void surfaces as solid surfaces. Such a structure is often referred to by the well-known English term “mesh”.

[0034] Figure 1 illustrates a bicycle stem according to the prior art. This stem consists of an elongated solid body whose ends form attachments adapted to cooperate with the adjacent parts of the bicycle, namely the handlebars and the steering stem. The solid metal structure makes it possible to obtain an inexpensive part with high mechanical strength and ease of manufacture. However, such a part has a relatively significant mass, which can negatively impact the dynamic characteristics of a high-performance bicycle.

[0035] Figures 2 to 4 illustrate different views of a rotational force transmission element 1 for steering a bicycle 10, in this example a stem 6, namely a perspective view in Figure 2, a top view in Figure 3, and a front view in Figure 4.

[0036] The arm 6 comprises an elongated body 2. In this embodiment, the body is ovoid in shape. The interior of the body 2 is entirely hollow. This longitudinal recess 3 forms a void. Consequently, the volumetric void ratio is greater than or equal to 25%, and more preferably greater than or equal to 30%, and even more preferably greater than or equal to 35%. In the illustrated example, it represents 35% of the part's volume.

[0037] The periphery or envelope of the body is formed by a lattice structure 5, creating a perforated envelope. As a result, the surface void ratio is greater than or equal to 25%, and more preferably greater than or equal to 30%. In the illustrated example, it represents 32% of the surface area of ​​the part.

[0038] Contrary to expectations, having a hollow body surrounded by an envelope with a plurality of openings allows the advantages of these two weight reduction methods to be combined, without weakening the strength and mechanical resistance characteristics of the part.

[0039] Each end of the body 2 has a mounting area 4. In the illustrated example, each of the mounting areas has a plurality of contact interfaces.

[0040] As illustrated in Figure 13, which shows a bicycle 10 equipped with various rotational force transmission components 1 for steering, a first mounting area allows the stem 6 to be fixed to the axle of the fork 14. The opposite mounting area allows fix the handlebar 11 to the stem 6.

[0041] Figure 5 illustrates a bicycle crankset lever (chainring side) according to the prior art. This lever-stem consists of an elongated solid body whose ends form attachments adapted to cooperate with the adjacent parts of the bicycle, namely the chainrings on one side and a pedal on the other. The solid metal structure makes it possible to obtain an inexpensive part with high mechanical strength and ease of manufacture. However, such a part has a relatively significant mass, which can negatively impact the dynamic characteristics of a high-performance bicycle.

[0042] Figures 6 to 8 illustrate different views of a rotational force transmission element for driving a bicycle, in this example a crank arm 7 on the side of the chainring(s), i.e. a front view in figure 6, a perspective view in figure 7, and a side view in figure 8.

[0043] The crank arm 7 comprises an elongated body 2. In this embodiment, the body comprises two beams of substantially parallel profiles, slightly spaced apart, forming a longitudinal recess 3. The thickness of the recess is close to that of one of the beams. On each side of the body 2, the ends of the beams meet, thus defining the length of the longitudinal recess 3. One side of the crank arm is specifically designed to cooperate with the outer chainring 13 of the crankset 12, as shown in the crankset example in Figure 12 and in the bicycle example 10 in Figure 13. In the embodiment shown in Figures 6 to 8, the beam intended to be against the outer chainring 13 extends beyond the longitudinal recess 3 to reach the central area of ​​the chainring 13.

[0044] To cooperate with the chainring(s), the mounting area 4 has four mounting tabs 15 extending transversely from the beams of the body 2, forming a symmetrical arrangement with two tabs on each side. Each tab 15 consists of a lattice structure 5 connecting to each of the beams. This double attachment of the tabs 15 to the body 2 provides an arrangement that allows forces to be transmitted to the crankset without risk of breakage or other mechanical failure related to the transmission of significant forces. This optimized arrangement also allows for weight reduction, contributing to very high-level performance, for example, during races or other competitions. The other side of the body 2 has a mounting area, for example, a threaded hole, for attaching a pedal.

[0045] Due to the planned architecture with a longitudinal recess 3 and a truss structure 5, the volumetric void ratio is greater than or equal to 25%, and more preferably greater than or equal to 30%, and even more preferably greater than or equal to 35%. In the illustrated example, it represents 45% of the volume of the part.

[0046] Figure 9 illustrates a crank arm (side opposite the chainrings) of a bicycle according to art front. This arm consists of an elongated solid body whose ends form attachments designed to engage with adjacent bicycle components, namely the bottom bracket axle on one side and a pedal on the other. The solid metal structure results in an inexpensive part with high mechanical strength and ease of manufacture. However, such a part has a relatively significant mass, which can negatively impact the dynamic characteristics of a high-performance bicycle.

[0047] Figures 10 and 11 illustrate different views of a rotational force transmission element for driving, in this example a crank arm 8 on the side opposite the chainring, with a perspective view in Figure 10, and a side view in Figure 11.

[0048] The crank arm 8 comprises an elongated body 2. In this embodiment, the body comprises two beams of similar profiles, substantially parallel and slightly spaced apart, forming a longitudinal recess 3 whose thickness in this example is close to that of one of the beams. On each side of the elongated body 2, the ends of the beams meet, thus defining the length of the longitudinal recess 3. One side of the crank arm is specifically designed to cooperate with the crank axle 12, as shown in the crank example in Figure 12 and in the bicycle example 10 in Figure 13. As illustrated in the embodiment shown in Figures 10 and 11, on the side intended to be fixed to the crank axle, the two beams meet and form a ring with a notch allowing for tightening once the arm is in place on the crank axle.The tightening is carried out, for example, using screws provided for this purpose. On the other side of the body 2, the fixing area 4 provides a threaded hole into which a pedal can be fixed.

[0049] This optimized arrangement also allows for mass savings contributing to achieving very high-level performance, for example during races or other competitions. As shown in Figure 11, a secondary recess 16 is arranged between the bottom bracket axle mounting area.

[0050] Due to the planned architecture with a longitudinal recess 3 and a secondary recess 16, the volumetric void ratio is greater than or equal to 25%, and more preferably greater than or equal to 30%, and even more preferably greater than or equal to 35%. In the illustrated example, it represents 45% of the volume of the part.

[0051] The various examples of rotational force transmission elements described above are advantageously made with lightweight materials with very high mechanical resistance, such as, for example, metallic alloys, in particular titanium-based, and / or preferably materials suitable for implementation by additive manufacturing.

[0052] Preferably, a titanium alloy in the form of a metal powder, Ti6A14V, also known as Ta6V, is used, with implementation by manufacturing additive, facilitating the implementation of the lattice structure and the recesses in the parts. List of reference signs

[0053] 1. Rotational force transmission element for steering a bicycle 2. Body lying down 3. Longitudinal or axial recess 4. Fixing area 5. Lattice structure 6. Gallows 7. Crank arm, chainring side 8. Crank arm on the side opposite the chainrings 9. 10. Bicycle 11. Handlebar 12. Crankset 13. Cranksets 14. Fork axle 15. Mounting brackets 16. Secondary evidence

Claims

Demands

1. A rotational force transmission element (1) for steering a bicycle (10), in particular a stem (6) or a crank arm (7, 8), comprising a centrally hollow elongated body (2) situated between two extreme attachment zones (4), one with a steering interface element, in particular a handlebar or a pedal, the other with the corresponding part of the bicycle, characterized in that the entire body (2) is made up of a lattice structure (5), in that at least one attachment zone (4) cooperates with the lattice structure (5), in that the surface void ratio is greater than or equal to 25%, and more preferably greater than or equal to 30% and even more preferably greater than or equal to 40%, and in that the volume void ratio is greater than or equal to 25%, and more preferably greater than or equal to 30% and even more preferably greater than or equal to 35%.

2. Rotational force transmission element (1) according to claim 1, consisting of a gantry (6).

3. A rotational force transmission element (1) according to any one of claims 1 or 2, wherein the body (2) is ovoid in shape, the interior of the body being entirely hollow, forming an empty chamber.

4. Rotational force element (1) according to claim 1, consisting of a crank arm (7) on the side of the chainring(s).

5. Rotational force transmission element (1) according to claim 4, wherein the area (4) for attachment to the chainrings (13) of the crankset comprises a plurality of attachment tabs (15).

6. Rotational force transmission element (1) according to claim 1, consisting of a crank arm (8) on the opposite side of the chainring(s).

7. Bicycle (10) comprising a rotational force transmission element (1) for driving the bicycle according to any one of claims 1 to 6.