Toothed plate with a reinforcement insert and Anti-wear protection

Abstract

The present invention relates to a toothed plate with a reinforcement insert and anti-wear protection that is to be used in a transmission system for bicycles or similar vehicles with transmission by means of sprockets and a chain. The chain (2), which is inserted into teeth (10) arranged around the periphery of the plate (1), has rollers (20) that are joined by means of joining plates (21) having a separation gap (23) between them that corresponds to the position of the teeth (10), so that they fit into same. The plate comprises, in the perimeter area thereof, at least two portions made of different materials, where a first structural portion (11) is made of a thermoplastic or thermoset carbon fibre and polymer matrix composite material, which forms the structure of the teeth (10). A second portion or insert (12) made of a harder material, which covers at least the front area (10a) part of the teeth (10) that make contact with the rollers (20) of the chain (2), is a metal alloy or ceramic material that defines an internal core of each tooth (10). The second portion is a structure with filiform segments that only cover the front area (10a) of each of the teeth (10), following the contour profile of all the teeth (10), and is in turn a flat sandwich-type structure between two external layers of the first portion (11). It comprises internal gripping elements (12a) to facilitate its attachment to the first portion (11) of the plate.

Description

[0001] DESCRIPTION

[0002] TOOTHED PLATE WITH REINFORCEMENT INSERT AND ANTI-WEAR PROTECTION

[0003] OBJECT OF THE INVENTION

[0004] The invention, as expressed in the title of this specification, relates to a toothed plate with a reinforcement insert and anti-wear protection that provides, for its intended function, advantages and characteristics, which are described in detail below.

[0005] The object of the present invention lies in a plate or toothed gear, of those used in transmission systems for bicycles and similar pedal vehicles, which has the particularity of comprising in the toothed area thereof, at least, two differentiated parts made, during its manufacture, of different materials, one of composite material of carbon fiber and polymer matrix, forming the structure of the teeth, since it provides rigidity, tensile strength and lightness, and another of greater hardness, for example a metal alloy or ceramic material, in the contact area of ​​the teeth with the chain, which determines an anti-wear protection, since it offers resistance to wear due to friction, so that the area that is in direct contact with the chain roller and that suffers all the compression and friction stress, being of a harder material than that which forms the structure of the tooth itself,It increases the durability of the tooth, allowing reinforcement only in the area that has a much more pronounced wear, while the rest of the tooth, as well as the rest of the plate, can have a lower coefficient of friction and form a lighter plate.

[0006] FIELD OF APPLICATION OF THE INVENTION

[0007] The field of application of the present invention falls within the sector of the industry dedicated to the manufacture of transmission systems, focusing particularly on the field of gear systems and more specifically on those intended for bicycles and vehicles with similar transmissions.

[0008] BACKGROUND OF THE INVENTION

[0009] In bicycles, the most commonly used transmission system is toothed gears and roller chains. The toothed gear that introduces power into the system through the pedals and cranks is often called the "chainring," and the output toothed gears that transmit power to the wheel are called "sprockets."

[0010] The chainrings on standard bicycle drivetrains are typically made primarily of steel or aluminum. Standard chainrings have a plurality of teeth arranged around the periphery, all of which fit within the interior space defined by the link plates of a standard bicycle roller chain. While some bicycle chainrings have used other materials, such as carbon fiber or other materials, these have not been commercially successful due to inadequate performance or cost.

[0011] Bicycle drivetrain chains, like any roller chain, are made up of different components, including rollers, plates, and pins. The rollers are responsible for transferring energy to the front teeth. The teeth, in turn, are designed to accommodate the roller and ensure it can transmit the force effectively. The chain plates are responsible for transferring this energy between the rollers, and the pins act as a link between the different components.

[0012] Roller chains are primarily made of steel. The rollers come into contact with the gear teeth, creating an interlock that transmits power. This interlock generates friction through use, which leads to wear on both the teeth and the chain itself. With use, the chain stretches, increasing the distance between the rollers. These rollers, having to mesh with the teeth, increase friction and accelerate wear.

[0013] Depending on the material used for the toothed gears and their hardness, their useful life will vary, with the lower the hardness of the material, being shorter.

[0014] Bicycle chains don't always run in alignment with the drivetrain. Having a gear selector, usually on the rear wheel, often causes the chain to run crosswise. This causes the side plates of the chain to rub against the sidewalls of the cog, generating friction and reducing efficiency. This friction isn't like that generated by the rollers against the front of the cog, since in this case there's no direct force pushing the plate perpendicularly against the cog. Instead, the force is longitudinal to the direction of the chain, and therefore isn't as abrasive as the force that enters through the rollers can be.

[0015] Friction between a toothed gear and a roller chain.

[0016] In any mechanical transmission, its efficiency is a determining factor, as it determines the energy losses of the system. Both weight and friction can be factors that are taken into account when determining this efficiency. A lower coefficient of friction means greater efficiency and less energy loss by the system itself, which in the cycling world translates into better utilization of the energy generated by the cyclist.

[0017] - Static friction: Friction between the front of the tooth and the chain roller.

[0018] Due to the force passing through the roller and the tooth, friction is generated between these two elements. This, combined with the elongation of the chain with use, causes the softer material—in this case, the material of the chainring teeth—to wear down in the area in contact with the rollers. Once these two elements are engaged, the contact between them is static, and the teeth are designed so that the chain does not touch until it has reached its working position, thus minimizing possible friction. The force of the tooth on the roller is normal to it, generating a high friction force that, in turn, generates significant wear in this specific area.

[0019] - Dynamic friction: Friction between the side of the tooth and the chain plates

[0020] In bicycle transmissions with gears, the chain works crosswise in many gear ratios, generating friction between the chain plates and the sides of the teeth. However, this friction is less, since the main force component is longitudinal to the direction of the chain itself, and the force component that generates this friction is related to the misalignment of the chain. Therefore, it is a lower friction force than that produced by the roller, but it also causes wear on the teeth in the long run.

[0021] Carbon fiber plates.

[0022] As is known, carbon fiber is a material that can be much more structurally resistant than any metal with a significant weight reduction thanks to its low density, and depending on the polymer with which the composite material is created, a material with a low coefficient of friction can be obtained, but it is also a soft material compared to some metals such as aluminum and steel alloys, which means that it can present greater wear against friction forces.

[0023] Although carbon fiber is a rigid, strong, and lightweight material, it is soft compared to metals. When in contact with a roller chain, mostly made of metal harder than carbon itself, the chain transmits force and elongates during use, generating friction between the two materials, which gradually wears down the softer material—in this case, the carbon teeth. Therefore, although the teeth are structurally strong, they are still soft, and their resistance to frictional wear is low. Therefore, the lifespan of a chainring made entirely of carbon fiber is shorter compared to that of a chainring made of other metal alloys.

[0024] The ideal, therefore, would be to take advantage of the advantages of both types of materials. Therefore, the objective of the invention is the development of an improved bicycle chainring, that is, a toothed chainring for chain transmission, whose structural configuration offers the wear resistance due to friction of metal alloys and, at the same time, the rigidity, tensile strength and lightness of carbon fiber.

[0025] On the other hand, and as a reference to the current state of the art, it should be noted that, at least on the part of the applicant, the existence of any other toothed plate, or any other invention of similar application, that presents technical, structural and constitutive characteristics equal to or similar to those claimed here, is unknown.

[0026] EXPLANATION OF THE INVENTION

[0027] The toothed plate with reinforcement insert and anti-wear protection that the invention proposes is configured as an optimal solution to the objective previously indicated which, in turn, represents an improvement of the current state of the art, the characterizing details that make it possible and that distinguish it being conveniently included in the final claims that accompany this description.

[0028] Specifically, what the invention proposes, as previously indicated, is a toothed plate or gear plate, of the type used in transmission systems for bicycles and similar pedal vehicles, which is fundamentally distinguished by comprising in the toothed perimeter area thereof, at least, two differentiated parts made of different materials, specifically the following:

[0029] - a first part preferably made of carbon fiber composite material and polymer matrix, forming the structure of the teeth, which provides rigidity, tensile strength and lightness, said matrix being able to be a thermoplastic or a thermoset; and

[0030] - a second part made of a material of greater hardness than the first part, for example a metal alloy or ceramic material, which covers at least the front area of ​​the teeth, which is the area of ​​contact between the teeth and the chain, offering greater resistance to wear due to friction and elongation of the chain.

[0031] For this purpose, the plate manufacturing process is preferably by insert molding, where the previously manufactured second part of the plate is inserted into a mold where the material that will form the first part of the plate is fixed around the second part. The fixing process can be, for example, by compressing the material of the first part of the plate onto the second part or by injecting the material of the first part of the plate onto the second part.

[0032] Once the chainring is manufactured and assembled for use, the second part of the chainring, made of the harder material, comes into contact with the drive chain roller at the front and center of the tooth, where the greatest forces and wear are generated.

[0033] In addition, the part that forms the structure of the teeth is made of a carbon fiber composite material, contributing to structural strength and reducing friction with the chain when it is not completely aligned with the teeth and its walls rub against the chain plates.

[0034] In any case, the second part or reinforcement insert can take different forms, from a shape that follows the tooth's own profile to a smooth, sandwich-like structure, or one that only provides material to the front part of the tooth.

[0035] The main advantage of the chainring of the present invention is that the area in direct contact with the chain roller, which bears all the compression and friction stress, is made of a harder material than the tooth structure itself. This increases the durability of the tooth and helps reinforce the area that experiences much greater wear, allowing the rest of the tooth to have a lower coefficient of friction and form a lighter chainring.

[0036] In one embodiment, the wear protection part or insert is made of metal. Preferably, said metal part can be manufactured by CNC machining (computer numerical control) if a constant thickness is not desired, by laser cutting, die-cutting, sintering, or obtained by other means.

[0037] In any case, said part can have different designs that facilitate both manufacturing and positioning as well as additional functionalities.

[0038] On the other hand, for the manufacture of the part that constitutes the structure of the tooth and, preferably, the rest of the plate, and which is made of carbon fiber, different technologies can be used, from the injection of thermoplastic material with a high fiber load, or even, preferably, it can be obtained by carbon compression, prepreg lamination, RTM or any manufacturing system for obtaining parts with carbon fiber.

[0039] DESCRIPTION OF THE DRAWINGS

[0040] To complement the description being made and in order to help better understand the characteristics of the invention, some sheets of drawings are attached to this descriptive report, as an integral part thereof, in which the following has been represented for illustrative and non-limiting purposes:

[0041] Figure 1 shows a side elevational view of the entire bicycle transmission system using a chainring, chain and sprockets, showing the arrangement of the different elements, especially the toothed chainring object of the invention; Figure 2 shows a schematic plan view of the transmission system assembly shown in Figure 1 , represented with the chain displaced in different positions; Figure 3 shows a perspective view of a section of the chain comprising the transmission system shown in Figures 1 and 2; Figure 4 shows a perspective view of the exploded view of the section of chain shown in Figure 3; Figure 5 shows an elevational view of the toothed chainring object of the invention, including the transmission chain represented in section coupled to it; Figure 6.- Shows an enlarged view of detail A shown in Figure 5, which allows the arrangement of the chain rollers to be appreciated, making contact with the front surface of the chainring teeth; Figure 7.- Shows a perspective view of the toothed chainring object of the invention, showing its general configuration; Figure 8.- Shows an enlarged perspective view of a portion of the chainring of the invention, showing the external configuration of the teeth, both on its front and side parts; Figure 9.- Shows a perspective view of a portion of the chainring, according to the invention, with the teeth partially sectioned, showing the arrangement of the anti-wear protection insert part, represented in black, in an example of the same that only covers the teeth on their front face; Figure 10.- Shows a perspective view of the plate of the invention, similar to that shown in Figure 9, in this case with an example of the insert part in which the entire contour of the teeth is followed; Figure 11.- Shows a perspective view of the plate of the invention, similar to that shown in Figures 9 and 10, in this case with an example of the sandwich-shaped insert part; and Figures 1, 2 and 13.- Show sectional views of the plate in two different embodiments of the insert part, one without and the other with gripping elements to facilitate its fixing to the structural part of the plate.

[0042] PREFERRED EMBODIMENT OF THE INVENTION

[0043] In view of the aforementioned figures, and in accordance with the adopted numbering, one can observe in them a non-limiting embodiment of the toothed plate with reinforcement insert and anti-wear protection of the invention, which comprises what is described in detail below.

[0044] Thus, as can be seen in said figures, the plate (1) of the invention is applicable for implementation in a transmission system for bicycles or similar vehicles with or without a motor, which, as can be seen in figures 1 and 2, comprises a chain (2) and one or more sprockets (3) such that, when force is applied, for example with pedals (4) associated with the plate (1) in the form of a disc with the chain (2) inserted in the teeth (10) arranged around the periphery thereof, it transmits the power to the sprockets (3) which, in turn, will move the wheel to whose axis they are coupled, said chain (2) being, as can be seen in figures 3 and 4, of those formed by rollers (20) joined by means of connecting plates (21) and bushings (22) forming links with a space (23) between them according to the position of the teeth (10) of the plate (1) so that they fit into said spaces (23).

[0045] In order to better understand the characteristics of the invention, looking at Figures 5 and 6, it can be seen how, when the aforementioned fit of the teeth (10) occurs in the spaces (23) existing in the chain (2) between the rollers (20), said rollers (20), when operating the transmission system, that is, when pedaling, make contact mainly on the front part (10a) of the teeth (10), there being in said teeth (10) a central area (10b) or valley, a rear area (10c) and a cusp (1 Od). In addition, the teeth (10) have a front side (a) on one side of the plate (1) and a rear side (b), on the opposite side of the plate (1) and a central surface (c) between both sides and on which the rollers (20) of the chain (2) fit and rub.

[0046] Well, from said already known configuration, the plate (1) of the present invention is distinguished by comprising, in the perimeter area thereof, where it comprises said teeth (10), at least two differentiated parts made of different materials: - a first part (11) made, mainly but not exclusively, of carbon fiber composite material and polymeric matrix, which forms the structure of the teeth (10), providing rigidity, tensile strength, lightness and low friction; and

[0047] - a second part or insert (12) for reinforcement and anti-wear protection, made of a material of greater hardness than the material of the first part (11) and covering, at least, the front area (10a) on the central surface (c) of the teeth (10), where said teeth (10) make contact with the rollers (20) of the chain (2).

[0048] Preferably, the carbon fiber composite matrix of the first part (11) of the plate (1) is a thermoplastic or a thermoset.

[0049] Preferably, the hardest material of the second part or insert (12) of anti-wear protection is a metal alloy or ceramic material.

[0050] In any case, in one embodiment option, the second part or insert (12) of anti-wear protection is a structure that defines an internal core in each tooth (10).

[0051] In other embodiment options, such as the one shown in figure 9, the second part or insert (12) of anti-wear protection is a structure of filiform segments that only cover the front area (10a) of each of the teeth (10) of the plate (1).

[0052] In another embodiment option, as shown in figure 10, the second part or insert (12) of anti-wear protection is a filiform structure that follows the contour profile of all the teeth (10).

[0053] And, in another embodiment option, as shown in figure 11, the second part or insert (12) of anti-wear protection is a flat sandwich-like structure between two external layers of the first part (11) of carbon fiber composite material and polymer matrix.

[0054] In turn, it should be noted that, preferably, the rest of the disc forming the plate (1) is also made of the same composite material of carbon fiber and polymer matrix as the first part (1) of the perimeter area of ​​the teeth (10). On the other hand, looking at Figures 12 and 13, it can be seen how the second part or insert (12) can have different shapes and designs. Thus, in one embodiment option, the second part or insert (12) of anti-wear protection has a design that is internally regular, that is, without protruding elements (Figure 12). However, in other embodiments, said second part or insert (12) is designed as a structure comprising internal gripping elements (12a) to facilitate its fixing to the first part (11) of the plate (Figure 13).

[0055] Finally, it should be mentioned that, although in the examples shown in the figures the plate (1) shown is of the type that has a design in which two different types of teeth are contemplated, some wider and shorter interspersed with others more pointed, this type of plate being especially intended for single-plate transmissions, to prevent the chain from coming off, it should be understood that the plate (1) with insert described and claimed can be of said type or any other type with any tooth design, and therefore, also for plates designed to work in combination with more plates and their respective adaptations to facilitate gear changes.

[0056] Having sufficiently described the nature of the present invention, as well as the manner of putting it into practice, it is not considered necessary to make its explanation more extensive so that any expert in the field understands its scope and the advantages derived from it.

Claims

CLAIMS 1.- Toothed plate with reinforcement insert and anti-wear protection, applicable in a transmission system, for bicycles or similar vehicles with transmission by sprockets and chain, with chain (2) and sprockets (3) where said chain (2), which is inserted in the teeth (10) arranged around the periphery of the plate (1), has rollers (20) joined by means of joining plates (21) with a space (23) between them according to the position of the teeth (10) so that they fit into them, it is characterized by comprising, in the perimeter area thereof where it comprises said teeth (10), at least, two differentiated parts made of different materials: - a first structural part (11), made mainly but not exclusively of carbon fiber composite material and polymer matrix, which forms the structure of the teeth (10), providing rigidity, tensile strength, lightness, low friction; and - a second part or insert (12) of anti-wear protection, made of a material of greater hardness than the aforementioned structural part (11), and which covers, at least, the part of the front zone (10a) of the teeth (10), where said teeth (10) make contact with the rollers (20) of the chain (2). 2.- Toothed plate with reinforcement insert and anti-wear protection, according to claim 1, characterized in that the matrix of the carbon fiber composite material of the first part (11) of the plate (1) is a thermoplastic or a thermoset. 3.- Toothed plate with reinforcement insert and anti-wear protection, according to claim 1 or 2, characterized in that the harder material of the second part or insert (12) of anti-wear protection is a metal alloy or is ceramic material. 4.- Toothed plate with reinforcement insert and anti-wear protection, according to any of the preceding claims, characterized in that the second part or insert (12) of anti-wear protection is a structure that defines an internal core in each tooth (10). 5.- Toothed plate with reinforcement insert and anti-wear protection, according to any of claims 1 to 3, characterized in that the second part or insert (12) of anti-wear protection is a structure of filiform segments that only cover the area front (10a) of each of the teeth (10) of the plate (1). 6.- Toothed plate with reinforcement insert and anti-wear protection, according to any of claims 1 to 3, characterized in that the second part or insert (12) of anti-wear protection is a filiform structure that follows the contour profile of all the teeth (10). 7.- Toothed plate with reinforcement insert and anti-wear protection, according to any of claims 1 to 3, characterized in that the second part or insert (12) of anti-wear protection is a flat sandwich-like structure between two external layers of the first part (11) of carbon fiber composite material and polymer matrix. 8.- Toothed plate with reinforcement insert and anti-wear protection, according to any of the preceding claims, characterized in that the second part or insert (12) of anti-wear protection is a structure comprising internal gripping elements (12a) to facilitate its fixing to the first part (11) of the plate.

Images