Bicycle chain

Abstract

The invention is a roller chain for bicycles, comprising a plurality of links (10, 20) hinged to one another in such a way that each link (10, 20) rotates with respect to the adjacent link (10, 20) around an axis (X), and wherein each link (10, 20) comprises at least one plate (100) consisting of a body (110) with two opposite ends (120, 130), in each of which there is a seat or hole (140) for the insertion of a connection pin (11). Said plates are made of spring steel and are elastically deformable in such a way that the distance between said two ends (120, 130) can vary as a result of the effort normally applied while pedalling.

Description

[0001] BICYCLE CHAIN

[0002] DESCRIPTION

[0003] The present patent concerns the bicycle sector and more specifically it concerns a new elastic articulated chain for bicycles.

[0004] Bicycles are known, in which the rear wheel is connected to a pedal-driven propulsion system through sprockets and a drive chain.

[0005] To simplify, at least one sprocket is connected to the hub of the rear wheel and to at least one sprocket that in turn is connected to the shaft of a pair of pedal cranks through a flexible drive chain forming a closed ring.

[0006] The chains currently used in bicycles are also known as roller chains (Galle chains), and are made up of a plurality of links, or rigid elements, hinged to one another in such a way that each link can rotate with respect to the adjacent link around a single axis, so that the chain is flexible on a single axis.

[0007] Each link is normally constituted by two facing rigid plates, which are constrained to each other by means of pins. More specifically, the known chains are constituted by a succession of outer links, that is, links with a greater distance between the two plates, alternating with inner links, that is, links with a smaller distance between the two plates, wherein the plates of the outer links are joined together by pins, while the plates of the inner links are joined together by bushings in which said pins are inserted in a rotatable manner, and where the bushings are in turn inserted in cylindrical tubular elements, called revolving rollers, which serve the function of spacers.

[0008] Each plate, which is made of a very rigid metallic material, is essentially in the shape of an 8, that is, it comprises a flat body with constant thickness with two rounded ends, into which the through holes for the insertion of the pins are drilled, and a central part joining the two ends.

[0009] The plates are usually symmetrical both with respect to a first longitudinal central axis passing through the centres of said holes made in the ends, and with respect to a second transverse central axis, orthogonal to said first longitudinal central axis and passing through the midpoint of the segment joining the centres of said holes made in the ends.

[0010] Plates in different shapes are also known, for example not symmetrical with respect to one or both axes or provided with one or more openings or lightened parts between the two ends.

[0011] An indispensable feature in the currently known drive chains for bicycles is the stiffness of the links. Indeed, it is a long-established misconception that chain links, and more particularly the plates that make them up, must be rigid, meaning non- deformable during normal use.

[0012] On the contrary, the applicant of the present patent has found that such stiffness is not completely suitable for the biomechanics of cycling, that is, for the musculoskeletal characteristics of cyclists.

[0013] The subject of the present invention is a new elastic articulated drive chain for bicycles, comprising in its main parts a plurality of links constrained to each other, and wherein one or more of said links can deform elastically in at least one direction during normal use of the chain in a bicycle, that is, when subjected to the normal stresses resulting from pedalling.

[0014] In a preferred solution, the new chain substantially comprises the same components as the known roller chains (Galle chains), but the plates are configured in a different manner, so that they can be elastically deformed to a certain extent in one direction, and more specifically in the direction defined by the longitudinal axis of the plate itself, so that the distance between the two ends of the plate can vary.

[0015] These plates are conveniently made of spring steel, for example S235JR steel.

[0016] According to a possible solution designed to achieve this result, one or more of said plates making up the links, and more preferably all the plates of all the links comprising the new chain feature at least one curvilinear section in said central part between the two ends, said curvilinear section being made of an elastically deformable material suited to deform elastically when tension is applied to the pins of the ends, thus permitting a controlled and functional extension of the length of the plate and, therefore, of the chain.

[0017] In the preferred solution, for example, the plate is provided with an opening obtained in said central part and configured to define two curvilinear sections.

[0018] Said opening is preferably symmetrical with respect to the axes of symmetry of the plate.

[0019] The configuration and the material used make at least said central part of each plate elastically deformable in the longitudinal direction during normal use of the chain in a common bicycle.

[0020] The elastic deformation of the chain, due to the action of the individual plates, has a double effect.

[0021] On the one hand, it affects the cyclist's pedalling movement, which becomes more uniform.

[0022] On the other hand, when the pedal is pushed, the potential elastic energy accumulated in one part of the chain (that is, in the part subjected to tension and which tends to elongate due to the elongation of the plates involved) is then returned when the pedal moves back.

[0023] More specifically, in the pedal stroke cycle, and considering only one of the two pedals for the sake of simplicity, the pedal is pushed downwards by the cyclist and completes an initial portion of its turn, from top to bottom. During this portion of the turn, the chain section under stress tends to elongate due to the elastic deformation of the involved plates, thus accumulating potential elastic energy.

[0024] In the continuation of the same pedal stroke, when the pedal is not pushed any longer and continues to move downwards and then returns to its initial position moving upwards, said chain section is no longer subjected to tension and tends to shorten again, thus contributing to the execution of the pedal stroke.

[0025] In conclusion, replacing the rigid plates of the known chains with the elastically deformable plates of the new chain helps the cyclist's pedalling movement, which thus matches more harmoniously the repetitive accelerations and decelerations occurring along the path and due to the circular movement of the pedal; it makes the cyclist's movement more adaptable to the varying effort conditions; it results, during the pedal stroke, in a less rigid and more comfortable impact of the foot sole in the medium and long term.

[0026] In other words, it makes the cyclist's effort more uniform when pedalling, because while it increases the effort needed to push the pedal, which is partly used to lengthen part of the chain, it also reduces the effort needed to bring the same pedal back upwards.

[0027] The characteristics of the new chain are better clarified in the following description, making reference to the drawings, which are attached by way of non-limiting example.

[0028] Figure 1 shows a three-dimensional view of one of the modules (1) forming the new chain, in turn comprising, for example, two pairs of links (10, 20) constrained to each other.

[0029] Figure 2 shows a plate (100), which is a component of the link, in detail, while Figure 3 shows a plate (100) in an elastically stretched configuration compared to the same plate when at rest, drawn with a broken line, wherein the deformation is represented so as to appear bigger for the sake of clarity.

[0030] Figure 4 shows another preferred embodiment of the plate (100’) only.

[0031] The new chain is preferably of the type known as roller chain (Galle chain), that is, a chain made up of a plurality of links (10, 20) hinged to one another in such a way that each link can rotate with respect to the adjacent link around a single axis (X), so that the chain is flexible on a single axis.

[0032] Each link (10, 20) consists of two plates (100) facing each other and spaced from each other by a given distance.

[0033] More specifically, the new chain may preferably comprise two types of alternating links: the so-called inner links (20) and the so-called outer links (10), wherein the distance between the plates (100) is greater in the outer links (10) and smaller in the inner links (20).

[0034] Each plate (100) is substantially in the shape of a number 8, that is, it comprises a flat body (110) with constant thickness with two preferably rounded ends (120, 130), in each of which there is a hole (140) for the insertion of the pins (11) connecting the plates (100) and the links (10, 20). Said holes (140) preferably have standard dimensions.

[0035] The plate (100) is preferably symmetrical with respect to a first longitudinal axis (101) passing through the centres of the holes (140) and is preferably symmetrical with respect to a second axis (102) orthogonal to said first longitudinal axis (101) at the midpoint of the segment joining said holes (140).

[0036] The central part (150) of the plate (100), meaning the part between the two ends (120, 130), comprises at least one curvilinear section (152, 153) made of a material able to deform elastically in the direction defined by said longitudinal axis (101) when subjected to the normal stress applied during a pedal stroke.

[0037] In the example shown in the figures, said central part (150) has a concave shape, that is, it has a narrowing with respect to the ends (120, 130), and furthermore it is provided with at least one central opening (151) that actually defines two symmetrical curvilinear sections (152, 153), that is, portions having an essentially curvilinear extension, for example arched with the concave side facing outwards.

[0038] Said curvilinear sections (152, 153) of said central part (150) are elastically deformable in the direction defined by said first axis (101).

[0039] In the preferred solution, the shape of said plates (100) is essentially that of the plates currently known and available on the market.

[0040] In the solution exemplified in Figure 1, said outer link (10) is, as already explained, formed by a pair of said facing plates (100), joined to each other by means of two pins (11), each inserted in the aligned holes (140) of the two plates (100). Said inner link (20) also consists of a pair of said facing plates (100), joined to each other by means of cylindrical tubular elements or bushings (12), which are mounted at the level of said holes (140) and in which said pins (11) are inserted in a rotatable manner.

[0041] Additional cylindrical tubular elements or spacer rollers (13) are mounted on the outside of said bushings (12).

[0042] Each link (10, 20) can rotate around said pins (11) with respect to the adjacent link (20, 10), thus making the chain flexible.

[0043] The chain made up in this way is thus elastically deformable when subjected to a tensile force having at least one component parallel to said first longitudinal axis (ioi).

[0044] As schematically shown in Figure 3, consider that, during normal pedalling, two opposing forces Fl, F2 are applied to the pins (11) in the holes (140) of the two ends (120, 130) of the plate (100). This results in the elongation of the plate (100), that is, the pins (11) are moved away from each other and the curvilinear sections (152, 153) widen outwards, with a consequent decrease in their curvature.

[0045] Said plates are preferably made of spring steel, for example S235JR steel.

[0046] Figure 2 shows that said opening (151) has a special shape intended to define, at the level of the area where each curvilinear section (152, 153) is joined to the ends (120, 130), a rounded concave connection section (154), in order to reduce notching and to maximise the length of the curvilinear section (152, 153), that is, the deformable section.

[0047] Figure 4 shows a plate (100’) with an opening (151’) having different dimensions and geometric shapes, designed to achieve different mechanical behaviours.

[0048] In particular, according to the invention, said opening (151’) can be made in such a way as to place it in communication with said holes (140’) for the pins (11), forming a single central opening with them. In this way, there is no ‘solid’ part between the holes (140’) and the opening (151’), where breakage points and cracks could form. In this solution, said opening (151’) has a shape that substantially follows the outer contour of the plate (100’), thus being narrower at the centre, and is provided with extensions (154’) that partially enclose the outside of said holes (140’).

[0049] The holes (140’) intended to house the pins (11) are therefore delimited by an outer circular or curvilinear portion (141’), that is, a portion facing towards the corresponding end (120, 130), while they are open towards the inside of the plate (100’). Considering a circular hole (140’), the amplitude (a) of the interruption of the hole (140’) is conveniently less than 180° and more preferably equal to 90°, in order to prevent the pin (11) from coming off the hole (141’), which is undesirable. In this solution, the curvilinear sections (152’, 153’) are further lengthened.

[0050] The overall opening obtained thus has a shape that substantially follows the contour of the plate (100), with two recesses defining the holes (140’) for housing the pins (H).

[0051] This configuration reduces the risk of cracks in the plate (100) and maximises its possible elongation.

[0052] It has been calculated that, considering a standard size plate in normal bicycle chains, the elongation obtained is equal to 1.1 -1.4 mm.

[0053] Therefore, with reference to the above description and the attached drawings, the following claims are made.

Claims

CLAIMS1. Roller chain for bicycles, comprising a plurality of links (10, 20) hinged to one another in such a way that each link (10, 20) rotates with respect to the adjacent link (10, 20) around an axis (X), and wherein each link (10, 20) comprises at least one plate (100) consisting of a body (110) with two opposite ends (120, 130), in each of which there is a seat or hole (140) for the insertion of a connection pin (11), characterized in that at least one of said plates (100) is elastically deformable in such a way that the distance between said two ends (120, 130) can vary as a result of the effort normally applied while pedalling.

2. Roller chain for bicycles according to claim 1, characterized in that the central part (150) of said plate (100) between said two ends (120, 130) comprises at least one curvilinear section (152, 153) joining said ends (120, 130), and wherein said at least one curvilinear section (152, 153) is made of an elastically deformable material.

3. Roller chain for bicycles according to claim 1 or 2, characterized in that said plate (100) is made of spring steel.

4. Roller chain according to the preceding claims, characterized in that said body (110) of each plate (100) is essentially in the shape of an 8, with said two ends (120, 130) substantially rounded and said central part (150) in a concave shape, narrower than the ends (120, 130), and wherein said at least one opening (15 l)in said plate (100) defines two substantially arched curvilinear sections (152, 153) with their concave side facing outwards.

5. Roller chain according to the preceding claims, characterized in that the shape of said opening (151) is such as to present a rounded concave section (154) at the level of the area where said curvilinear sections (152, 153) are joined to said ends (120, 130).

6. Roller chain according to the preceding claims, characterized in that said plate (100) is symmetrical with respect to a first axis (101) passing through said holes (140) and is symmetrical with respect to a second axis (102) orthogonal to said first axis (101)at the midpoint of the segment joining said holes (140).

7. Roller chain according to the preceding claims, characterized in that said opening (151’) is placed in communication with said holes (140’), creating a single opening inside the plate (100’).

8. Roller chain according to claim 7, characterized in that each of said holes (140’) is delimited by an outer circular or curvilinear portion (141’), that is, a portion facing towards the corresponding end (120, 130), while it is open towards the inside of the plate (100’), and wherein the amplitude (a) of the interruption of the hole (140’) towards the inside of the plate (100’) is less than 180° and more preferably equal to 90°.

9. Roller chain according to claim 7, characterized in that said opening (151’) comprises extensions (154’) that partially enclose the outside of said holes (140’).

10. Roller chain according to the preceding claims, characterized in that said body (110) of each plate (100) is flat and has constant thickness.

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