VARIABLE TRANSMISSION SYSTEM FOR CYCLES AND ASSOCIATED PEDAL CYCLES

Abstract

The invention relates to a variable transmission system (10) comprising: - a conical input roller (11) connected to an input roller shaft (11-1) arranged to drive the conical input roller in rotation, - a conical output roller (12) connected to an output roller shaft (12-1) arranged to drive the output roller shaft (12-1) in rotation, - an intermediate roller (13), a displacement means (14) arranged to slide from an initial transmission position in which the intermediate roller (13) is in contact with the smallest diameter (11-2) of the conical input roller (11) and with the largest diameter (12-3) of the conical output roller (12), to a final transmission position in which the intermediate roller (13) is in contact with the largest diameter (11-3) of the input roller (11). conical and with the smallest diameter (12-2) of the output roller (12) conical. Figure to be published with the abbreviation: figure 1

Description

Title of the invention: VARIABLE TRANSMISSION SYSTEM FOR BICYCLES AND ASSOCIATED PEDAL BICYCLES technical field

[0001] The invention relates to the field of variable transmissions, particularly for bicycles. In particular, the present invention relates to a variable transmission for a two-wheeled bicycle. The solution developed by the applicant aims to replace the traditional bicycle derailleur with a new power transmission system. This system is characterized by its smooth gear changes, its wide range of gear ratios (speed / torque), its quiet operation, and its installation on the bottom bracket, thus avoiding the shocks and damage common with traditional derailleurs.

[0002] The invention further relates to a pedal cycle which includes such a variable transmission system. Previous technique

[0003] Below, we describe the prior art known from which the invention was developed.

[0004] In recent years, vehicles associated with so-called soft mobility, such as two-wheelers, bicycles, tandems, cargo bikes, scooters, etc., as well as those used for transporting goods (for example, motorized carts or electric-assist trailers), have experienced significant growth. Electric assistance is often included and plays an important role in reducing polluting and noise emissions, making these vehicles easier to use, and minimizing the environmental impact on users. To facilitate travel in urban centers, technological advances have led to the emergence of high-performance and efficient solutions that support the increasingly frequent and intensive use of bicycles. This mode of transport is becoming increasingly popular due to its versatility, durability, and low environmental impact.

[0005] The ever-increasing daily use of cycles, whether electrically assisted or not, is accompanied by the development of the cycle part and more particularly the transmission system to improve the user's riding experience.

[0006] In order to improve the integration of variable transmission systems and the transmission ratio, solutions have emerged.

[0007] For example, patent application no. WO2024120815, which relates to the field of variable transmission for electrically assisted land vehicles, proposes a solution aimed at optimizing the space and integrating a variable transmission to facilitate its use within a vehicle. To this end, this solution incorporates a variable transmission using at least one conical or frustoconical input roller, one conical or frustoconical output roller, and a ring gear that cooperates with the conical or frustoconical rollers and moves axially to vary the transmission ratio. In this solution, the generatrix of each roller in contact with the ring gear is parallel to the input and output shafts of the variable transmission. Thus, the movement of the ring gear is parallel to the input and output shafts, which allows for a simple and compact design of the transmission ratio variation system.

[0008] Other patent applications, such as patent document CN103711854, describe a variable transmission with tapered rollers and a ring gear. The implementation of these tapered rollers and the ring gear requires a complex movement of the ring gear that is not parallel to the axes of the input and output shafts, which implies assembly and implementation complexity. Furthermore, such a ring gear does not have a naturally stable position; it must be held in place by external elements.

[0009] However, the use of an external ring gear still results in a significant radial footprint, and the variation in the transmission ratio is not substantial enough. Finally, the transmission ratio can also be improved.

[0010] The invention aims to overcome the drawbacks of the prior art. In particular, the invention aims to provide a variable transmission system which has a reduced size once integrated into a cycle, and which offers a wide range of speed ratios, adapting to the specific needs of the cyclist in terms of speed and torque and which makes it possible to do without a conventional derailleur.

[0011] The invention further aims to provide a pedal-powered cycle comprising such transmission system. Summary of the invention

[0012] The invention aims to overcome these drawbacks. The following presents a simplified summary of selected aspects, embodiments, and examples of the present invention in order to provide a basic understanding of the invention. However, this summary does not constitute an exhaustive overview of all aspects, embodiments, and examples of the invention. Its sole purpose is to present selected aspects, embodiments, and examples of the invention in a concise form by way of introduction. to the more detailed description of the aspects, embodiments and examples of the invention which follow the summary.

[0013] The invention relates in particular to a variable transmission system comprising: - a conical input roller connected to an input roller shaft arranged to drive the conical input roller in rotation, said input roller being further arranged to form a mechanical link with a frame, - a conical output roller connected to an output roller shaft arranged to drive the output roller shaft in rotation, the input roller shaft and the output roller shaft being substantially parallel, - an intermediate roller, positioned between the conical input and output rollers, the intermediate roller being arranged to transmit the rotational movement of the conical input roller to the conical output roller, said intermediate roller comprising in addition to an intermediate roller axis arranged to form a mechanical link with a frame axis by means of a displacement means arranged to slide, along the frame axis so as to permit a translation of the intermediate roller from an initial transmission position in which the intermediate roller is in contact with the smallest diameter of the conical input roller and with the largest diameter of the conical output roller, to a final transmission position in which the intermediate roller is in contact with the largest diameter of the conical input roller and with the smallest diameter of the conical output roller. The system according to the invention allows for increased fluidity during gear changes, which are thus made without jerking, while allowing for a widening of the speed / torque reduction ratios and thus ensuring a wide range of speed ratios.

[0014] Depending on other optional features of the system, the latter may optionally include one or more of the following features, alone or in combination: - The conical input roller and the conical output roller cooperate by friction with the intermediate roller. This ensures quiet operation of the system. - The intermediate roller is a toothless wheel. This ensures optimal, smoother power transmission, while eliminating the need for an external sprocket, thus reducing the system's size. - A preload actuator arranged to allow adjustment of a predetermined pressure on the conical input and output rollers relative to the intermediate roller. This ensures contact pressure between the elements to guarantee efficient power transmission. - The contact surfaces of the input roller shaft and the output roller shaft with the intermediate roller are respectively parallel to the intermediate roller shaft. This ensures permanent contact and constant friction between the intermediate roller, as it moves, and the conical input and output rollers. - The smallest diameter of the conical input roller is positioned approximately opposite the largest diameter of the conical output roller, and vice versa. This allows for a decrease in transmitted rotational speed and an increase in torque when the intermediate roller is positioned at the point where the smallest diameter of the conical input roller meets the largest diameter of the conical output roller, and an increase in transmitted rotational speed while decreasing torque when the intermediate roller is positioned at the point where the largest diameter of the conical input roller meets the smallest diameter of the conical output roller. - The output roller shaft is arranged to form a mechanical link with a chain sprocket, belt pulley, or wheel. - The input roller is connected to the input roller shaft by an epicyclic gear train. The epicyclic gear train is preferably arranged within the input roller. This improves the speed / torque reduction ratio while reducing the system's overall size. - The epicyclic gear train comprises a planet carrier connected to the input roller shaft, a fixed solar planet gear connected to the frame, planets held in position by the planet carrier, and a ring gear connected to the input roller. This allows the meshing stresses to be distributed across the planets, thus limiting planet wear.

[0015] According to a second object, the invention relates to a pedal cycle comprising a frame, a pair of pedals, and a variable transmission system according to the invention, the pair of pedals being mounted on the input roller axle, said input roller being further connected to the frame. The transmission system according to the invention, by virtue of its compact size, allows for easy integration into the frame of the pedal cycle, thus providing protection against external damage (shocks, impacts) and eliminating the need for a traditional derailleur, which is much more exposed and vulnerable.

[0016] According to other optional features of the process, the latter may optionally include the following features: - a gear lever connected to the means of movement so as to control the translational movement of the intermediate roller. Brief description of the drawings

[0017] Other features and advantages of the invention will be better understood from the following description and with reference to the attached drawing, given by way of illustration and not limiting.

[0018] [Fig-1] Fig. 1 represents a diagram of a first embodiment of a variable transmission system according to the invention.

[0019] [Fig.2] Fig.2 represents a diagram of a second embodiment of a variable transmission system according to the invention.

[0020] The figures do not necessarily respect the scales, particularly in thickness, for illustrative purposes.

[0021] Aspects of the present invention are described with reference to functional diagrams of devices (systems) according to embodiments of the invention. Description of embodiments

[0022] Below, we describe a summary of the invention and the associated vocabulary, before presenting the disadvantages of the prior art, and finally showing in more detail how the invention remedies them.

[0023] Thus, as illustrated in [Fig.1], the invention relates to a variable transmission system 10 which includes a conical input roller 11, an input roller shaft 11-1, an output roller 12, an output roller shaft 12-1, an intermediate roller 13, an intermediate roller shaft 13-1 and a displacement means 14.

[0024] According to the invention, the conical input roller 11 is connected to an input roller shaft 11-1 arranged to drive the conical input roller 11 in rotation. Furthermore, the input roller 11 is arranged to form a mechanical connection with a frame 2. For example, the input roller 11 may include one or more elements for ensuring a fixed mechanical connection with the frame 2 while allowing rotation of the conical input roller 11. The frame may correspond to a part of a bicycle frame within which the transmission system 10 can be positioned.

[0025] The transmission system 10 according to the invention further comprises a conical output roller 12 connected to an output roller shaft 12-1 arranged to drive the output roller shaft 12-1 in rotation. In order to ensure optimal transmission, the input roller shaft 11-1 and the output roller shaft 12-1 are substantially parallel.

[0026] Preferably, the output roller shaft 12-1 can be arranged to form a mechanical link with a chain sprocket, a belt pulley, or a wheel.

[0027] In the invention, the mechanical transmission of the movement from the conical input roller 11 to the conical output roller 12 is ensured by the intermediate roller 13. Indeed, the intermediate roller 13 is positioned between the input roller 11 and the output roller 12. conical, and is arranged to transmit the rotational movement from the conical input roller 11 to the conical output roller 12.

[0028] By way of non-limiting example, the conical input roller 11 and the conical output roller 12 can cooperate by friction with the intermediate roller 13. For this purpose, the intermediate roller 13 can be a toothed wheel. Indeed, as illustrated in Figures 1 and 2, the intermediate roller 13 has a contact surface with the conical input roller 11 and the conical output roller 12 which allows the transmission of motion between said rollers.

[0029] In order to ensure optimal transmission of motion, the contact surfaces of the input roller shaft 11-1 and the output roller shaft 12-1 with the intermediate roller 13-1 can respectively be parallel with the intermediate roller shaft 13-1.

[0030] In the context of the invention, the intermediate roller shaft 13-1 is connected to the intermediate roller and is arranged to form a mechanical link with the frame shaft 15 via the displacement means 14. The displacement means 14 is arranged to slide along the frame shaft 15 so as to allow translation of the intermediate roller 13 from an initial transmission position to a final transmission position. Speed ​​changes are thus enabled by the translation of the displacement means 14 along the conical input roller 11 and the conical output roller 12.

[0031] For this purpose, the means of displacement 14 may include a trapezoidal thread screw 16 whose rotation makes it possible to ensure the translation of said means of displacement 14, thus modifying the position of the intermediate roller 13 and, consequently, the speed ratio.

[0032] In the initial position, the intermediate roller 13 is in contact with the smallest diameter 11-2 of the conical input roller 11 and with the largest diameter 12-3 of the conical output roller 12.

[0033] In the final position, the intermediate roller 13 is in contact with the largest diameter 11-3 of the conical input roller 11 and with the smallest diameter 12-2 of the conical output roller 12.

[0034] In an embodiment of the transmission system 10 according to the invention, the smallest diameter 11-2 of the conical input roller 11 can substantially face the largest diameter 12-3 of the conical output roller 12 and the largest diameter 11-3 of the conical input roller 11 can substantially face the smallest diameter 12-2 of the conical output roller 12.

[0035] In order to maintain contact pressure and ensure transmission by friction, the variable transmission system 10 according to the invention may include a preload actuator arranged to allow adjustment of a pressure predetermined position of the conical input rollers 11 and output rollers 12 relative to the intermediate roller 13. In addition, to ensure such retention, the preload actuator may include a spring arranged between the conical output roller 12 and the output roller shaft 12-1.

[0036] In a particular embodiment of the transmission system according to the invention, the input roller 11 can be connected to the input roller shaft 11-1 by an epicyclic gear train. The epicyclic gear train is preferably arranged within the input roller 11-1 in order to optimize the overall dimensions of the transmission system.

[0037] In addition, the epicyclic gear train may include a planet carrier 25 connected to the input roller shaft 11-1, a fixed sun gear 23 connected to the frame 2, planets 24 held in position by the planet carrier 25, and a ring gear 26 connected to the input roller 11. The sun gear may, for example, be a central gear, and the planets may be planetary gears. The various elements of the epicyclic gear train preferably cooperate through mechanical linkages of the gear type. The planets may also be arranged around the input roller shaft 11-1 in order to further optimize the available space.

[0038] According to a second aspect, the invention relates to a pedal cycle comprising a frame 2, a pair of pedals 21-1, 21-2, and a variable transmission system 10 according to the invention. The pair of pedals 21-1, 21-2 is mounted on the input roller axle 11-1, more particularly at the ends of the input roller axle 11. The transmission system 10 is integrated inside the frame to ensure effective protection during use of the cycle; thus, the input roller 11 is also directly connected to the frame 2.

[0039] In one embodiment of the pedal cycle according to the invention, said pedal cycle may include a gear lever connected to the means of movement 14, so as to control the translational movement of the intermediate roller 13.

[0040] By way of non-limiting example, the rotation of the gear lever can cause the trapezoidal thread screw 16 to rotate, which ensures the translation of the means of movement 14 in order to change the speed ratio.

[0041] The invention can be the subject of numerous variations and applications other than those described above. In particular, unless otherwise indicated, the various structural and functional features of each of the embodiments described above should not be considered as combined and / or closely and / or inextricably linked to one another, but rather as mere juxtapositions. Furthermore, the structural and / or functional features of the various embodiments described above may be the subject, in whole or in part, of any different juxtaposition or any different combination.

Claims

Demands

1. Variable transmission system (10) comprising: - a conical input roller (11) connected to an input roller shaft (11-1) arranged to drive the conical input roller (11) in rotation, said input roller (11) being further arranged to form a mechanical connection with a frame (2), - a conical output roller (12) connected to an output roller shaft (12-1) arranged to drive the output roller shaft (12-1) in rotation, the input roller shaft (11-1) and the output roller shaft (12-1) being substantially parallel, - an intermediate roller (13), positioned between the conical input roller (11) and output roller (12), the intermediate roller (13) being arranged to transmit the rotational motion of the conical input roller (11) to the conical output roller (12),said intermediate roller comprising, in addition to an intermediate roller shaft (13-1) arranged to form a mechanical connection with a frame shaft (15) by means of a displacement means (14) arranged to slide along the frame shaft (15) so as to allow translation of the intermediate roller (13) from an initial transmission position in which the intermediate roller (13) is in contact with the smallest diameter (11-2) of the conical input roller (11) and with the largest diameter (12-3) of the conical output roller (12), to a final transmission position in which the intermediate roller (13) is in contact with the largest diameter (11-3) of the conical input roller (11) and with the smallest diameter (12-2) of the conical output roller (12).

2. Variable transmission system (10) according to claim 1, wherein the conical input roller (11) and the conical output roller (12) cooperate by friction with the intermediate roller (13).

3. Variable transmission system (10) according to claim 1 or 2, wherein the intermediate roller (13) is a toothless wheel.

4. Variable transmission system (10) according to any one of claims 1 to 3, said system comprising a preload actuator arranged to permit adjustment of a pressure predetermined input rollers (11) and output rollers (12) conical with respect to the intermediate roller (13).

5. Variable transmission system (10) according to any one of claims 1 to 4, wherein contact surfaces of the input roller shaft (11-1) and of the output roller shaft (12-1) with the intermediate roller (13-1) are respectively parallel with the intermediate roller shaft (13-1).

6. Variable transmission system (10) according to any one of claims 1 to 5, wherein the smallest diameter (11-2) of the conical input roller (11) substantially faces the largest diameter (12-3) of the conical output roller (12) and the largest diameter (11-3) of the conical input roller (11) substantially faces the smallest diameter (12-2) of the conical output roller (12).

7. Variable transmission system according to any one of claims 1 to 6, wherein the output roller shaft (12-1) is arranged to form a mechanical link with a chain sprocket, a belt pulley, or a wheel.

8. Variable transmission system according to any one of claims 1 to 7, wherein the input roller (11) is connected to the input roller shaft (11-1) by an epicyclic gear train.

9. Variable transmission system according to claim 8, in which the epicyclic train comprises a planet carrier (25) connected to the input roller shaft (11-1), a fixed solar planet (23) connected to the frame (2), planets (24) held in position by the planet carrier (25) and a ring gear (26) connected to the input roller (11).

10. Pedal cycle (1) comprising a frame (2), a pair of pedals (21-1, 21-2) and a variable transmission system (10) according to any one of claims 1 to 9, the pair of pedals (21-1, 21-2) being mounted on the input roller axle (11-1), said input roller (11) being further connected to the frame (2).

11. Pedal cycle (1) according to claim 10, said pedal cycle comprising a gear lever connected to the means of movement (14) so ​​as to control the translational movement of the intermediate roller (13).