System for driving the rear wheel of an electrically assisted bicycle

Abstract

The present invention relates to a system for driving the rear wheel (7) of an electric-assisted bicycle, the system comprising: a rear support (3) adapted to support the rear wheel (7); and an electric motor adapted to be coupled to the crank assembly (8) to rotate the crank assembly, the motor including a stator (45), a rotor (46) and a transmission arranged to convert rotational motion of the rotor (46) into rotational motion of the crank assembly, the crank assembly being adapted to rotate the rear wheel (7) via a drive (70), wherein the rear support (3) includes a first cavity (40) and a second cavity (50), the rotor (46) and the stator (45) being arranged in the first cavity, the transmission being arranged in the second cavity, and wherein the second cavity (50) contains a lubricant and is sealed with the lubricant relative to the first cavity (40).

Description

Technical Field

[0001] This invention relates to a system for driving the rear wheel of an electric-assisted bicycle. Background Technology

[0002] The market for electric-assist bicycles is expanding rapidly, enabling users to travel longer distances and / or climb hilly terrain.

[0003] In existing bicycles, the motor unit is mounted in a housing assembled onto the bicycle frame, and the motor is connected to the rear wheel so that it can be driven to rotate.

[0004] Typically, the goal is to reduce the weight and size of electric-assist bicycles. At the same time, structural components must resist mechanical stress and possess good rigidity.

[0005] Another issue involves the dissipation of heat generated by the motor when the bicycle is in use. Summary of the Invention

[0006] One object of the present invention is to design an electric-assisted bicycle in which the motor is integrated in a simpler manner, thereby reducing the weight of the bicycle and the number of components.

[0007] For this purpose, the present invention provides a system for driving the rear wheel of an electric-assisted bicycle, comprising:

[0008] • Rear stay, configured to be mounted on the front triangular member of the frame, the rear stay being adapted to support the rear wheel, and

[0009] • An electric motor adapted to be coupled to the crank assembly to rotate the crank assembly, the motor including a stator, a rotor rotatably movable relative to the stator, and a transmission arranged to convert the rotational motion of the rotor into rotational motion of the crank assembly, the crank assembly being adapted to rotate the rear wheel via a drive mechanism.

[0010] The rear support includes a first housing and a second housing. The rotor and the stator are arranged in the first housing, and the transmission device is arranged in the second housing. The second housing contains lubricant, which is sealed relative to the first housing.

[0011] This design eliminates the need for a motor housing, reducing the bicycle's weight and size at the motor. It also allows for a more compact frame construction and offers greater design freedom compared to existing solutions, while maintaining stability.

[0012] The aforementioned arrangement of the motor also allows for more efficient dissipation of the heat generated by the motor.

[0013] Preferably, the motor further includes an output shaft that is driven to rotate by a transmission device and rotates integrally with the crank assembly, the output shaft being arranged at least partially in the second housing.

[0014] Advantageously, the transmission also includes a gearbox or continuously variable transmission system arranged in the second housing, which allows selective changing of the ratio between the rotor speed and the crank assembly speed.

[0015] The rear support can be obtained through molding.

[0016] Advantageously, the first and second housings are integrally formed in the rear support.

[0017] Preferably, the drive system further includes a reinforcing structure integrated into the wall of the rear support. The reinforcing structure may include multiple reinforcing ribs.

[0018] Advantageously, the second housing includes a pair of holes configured to allow a drive mechanism for connecting the crank assembly to the rear wheel to pass through.

[0019] Advantageously, the first housing includes one or more heat dissipation holes.

[0020] Preferably, the first housing includes an opening and a removable maintenance cover arranged to close the opening.

[0021] The present invention also relates to an electric bicycle, comprising:

[0022] • A frame, which includes a front triangular piece attached to a fork that carries the front wheel.

[0023] •- As described above, in this drive system, the rear bracket is mounted on the front triangular member.

[0024] • The rear wheel carried by the rear support, and

[0025] • A drive unit that connects the crank assembly to the rear wheel, such that rotation of the crank assembly drives rotation of the rear wheel.

[0026] Preferably, the drive device is a belt, chain, or shaft.

[0027] Advantageously, the motor is arranged in the crankshaft.

[0028] Advantageously, the front triangular member includes a hollow inclined tube that receives an electrical connection to the battery of the motor.

[0029] In some embodiments, the frame is further provided with a front suspension and a rear suspension, the rear bracket being pivotally mounted on the front portion of the front triangular member in a single-pivot type, and the rear suspension being arranged between the rear bracket and the rear portion of the front triangular member.

[0030] The bicycle may include at least one rear wheel support mounted on a rear stand, the support being adjustable between a drive unit mounting position and a tensioned position of the drive unit located behind the front stand relative to the mounting position.

[0031] Preferably, the rear support includes a guide device, such as an elliptical hole, and each rear wheel support is mounted on the rear support by a screw engaging in the guide device.

[0032] Bicycles can exist without a mechanical tensioning system that drives the vehicle. Attached Figure Description

[0033] Other features and advantages will become apparent from the following detailed description with reference to the accompanying drawings, in which:

[0034] - Figure 1 This is a right-side view of a bicycle including the drive system of the present invention.

[0035] - Figure 2 This is an exploded diagram of the drive system.

[0036] - Figure 3 yes Figure 1 Another exploded view of the drive system in the diagram.

[0037] - Figure 4 This is a top view of the drive system of the present invention.

[0038] - Figure 5 yes Figure 3 A perspective view of the drive system in the image.

[0039] - Figure 6 yes Figure 3 Another perspective of the drive system in the diagram. Detailed Implementation

[0040] In this disclosure, the terms "front" and "rear," "front part" and "rear part" should be understood as referring to the direction of travel of the bicycle. The terms "right," "left," "horizontal," "up," and "down" should be understood as referring to the position of the bicycle when traveling on a horizontal surface.

[0041] Figure 1 This is an overall view of an electric-assisted bicycle 100 including the drive system of the present invention. The bicycle includes a frame, which includes a front triangular member 2 and a rear support 3.

[0042] The rear bracket 3 is mounted on the front triangular piece 2 of the frame, typically at the crank assembly 8. The rear end of the rear bracket 3 carries the rear wheel 7.

[0043] The bicycle 100 includes an electric motor arranged in a rear support near the crank assembly 8. Preferably, the motor is arranged in a shaft 88 of the crank assembly 8. The electric motor is coupled to the crank assembly 8, which in turn is coupled to the rear wheel 7 and is intended to drive the rear wheel 7 to rotate.

[0044] The motor includes a stator 45 and a rotor 46 that rotates relative to the stator.

[0045] By way of non-limiting illustration, the stator 45 includes a plurality of winding elements arranged in a ring around the axis of rotation of the rotor 46. An alternating magnetic field is generated by the windings of the stator 45. The rotor 46 includes one or more permanent magnets that interact with the alternating magnetic field of the stator 45, thereby driving the rotor 46 to rotate. In operation, the rotor 46 typically has a rotational speed between 8,000 and 18,000 rpm.

[0046] The motor also includes a transmission mechanism that allows the rotational motion of the rotor 46 to be converted into the rotational motion of the crank assembly 8. Figure 2 and Figure 3 In the transmission device, there is a gearbox 55, which includes a reduction system 51, a plurality of small gears of different sizes meshing with each other, and an output shaft 81 that rotates integrally with the crank assembly 8.

[0047] The gearbox 55 may additionally have bearings to facilitate the rotation of the corresponding pinion. Some bearings may be threaded onto the output shaft 81.

[0048] The gearbox 55 allows the user to change the torque between the rotor 46 and the crank assembly 8 of the bicycle, thereby selecting the ratio between the rotational speed of the rotor 46 and the rotational speed of the crank assembly 8. The rotor 46 causes the crank assembly 8 to move via the reduction gear system 51 of the gearbox 55.

[0049] In other embodiments (not shown), the transmission includes a continuously variable transmission (CVT). The CVT system includes a belt for continuously adjusting the speed ratio between the motor and the wheels.

[0050] In other embodiments (not shown), the transmission may be without a gearbox and continuously variable transmission system. In this case, the transmission only allows the rotational motion of the rotor 46 to be converted into the rotational motion of the crank assembly 8, but it is not possible to change the torque between the rotor 46 and the crank assembly 8.

[0051] When the drive system includes neither a gearbox nor a continuously variable transmission system, the transmission device is more... Figure 2 and Figure 3The transmission mechanism is simpler. It includes a reduction system 51 with an output shaft 81 that rotates integrally with the crank assembly 8. The transmission may also include fewer pinions than those in a gearbox. In this case, the ratio between the rotor 46's rotational speed and the crank assembly's rotational speed is predetermined and cannot be changed by the user.

[0052] The transmission converts the motion of rotor 46 into rotational motion of the output shaft, and thus into rotational motion of crankset 8. The rotational motion of output shaft 81 and crankset 8 has a lower speed and higher torque than the rotational motion of rotor 46. Typically, when the electric bicycle is in use, the speed of crankset 8 is between 40 rpm and 150 rpm, and can optionally be modified via gearbox 44 or a continuously variable transmission (CVT).

[0053] The rotor 46 is connected to the gearbox 55 or a transmission device, for example, via the spindle 43.

[0054] The crank assembly 8 is configured to actuate the drive mechanism 70, such as a chain, belt, or shaft. The drive mechanism 70 moves on an element 77 coaxial with the rear wheel, thereby driving the rear wheel to rotate. The element 77 coaxial with the rear wheel can be a pinion, a gearbox, a continuously variable transmission (CVT), a sprocket designed to be belt-driven, or a shaft-driven fixed device.

[0055] At crank assembly 8, drive unit 70 can be engaged with gears, sprockets designed to run belts, or shaft drive fixtures.

[0056] refer to Figures 2 to 4 The bicycle's rear support 3 includes a first housing 40 and a second housing 50 designed to house motor components. By way of non-limiting illustration, the first housing 40 has a smaller volume than the second housing 50. The first housing 40 may be arranged in the front portion of the rear support 3. In some embodiments, the first housing 40 is offset to one side of the rear support, for example, offset to the right side, as... Figure 4 and Figure 5 As shown. In other embodiments, the first housing may be offset to the left of the rear support, or it may be positioned centrally. The first housing preferably has a substantially cylindrical geometry, with the axis of the cylinder transverse to the direction of travel of the bicycle and parallel to the axle 88 of the crankset 8 and the axle 77 of the rear wheel 7.

[0057] The second housing 50 is advantageously positioned between the first housing 40 and the shaft 88 of the crank assembly 8. The first housing 40 and the second housing 50 are generally adjacent to each other and separated by a wall 49.

[0058] The rotor 46 and stator 45 are arranged in the first housing 40. The cylindrical shape of the housing 40 allows these components to be accommodated with minimal space requirements. The rotation axis of the rotor and the direction of the main shaft 43 correspond to the axis of the first housing and are parallel to the shaft 88 of the crank assembly 8.

[0059] Any electrical connectors and cables intended to supply power to the stator, as well as the electronic circuitry for driving the motor, may also be arranged in the first housing 40. The first housing does not contain any lubricant to prevent possible short circuits caused by current conduction in the lubricant and to ensure proper electrical operation of the rotor 46 and stator 45.

[0060] At least a portion of the gearbox 55 or continuously variable transmission system, the reduction system 51, and the output shaft 81 is arranged in the second housing 50. A portion of the output shaft 81 is connected to the crank assembly 8 and may protrude from the second housing 50.

[0061] The second housing also contains a lubricant designed to lubricate the gearbox, reduction gear system, any bearings, output shaft, and drive mechanism. Typically, this lubricant is oil. The lubricant ensures smooth operation and prevents the motor's mechanical parts from seizing.

[0062] The second housing sealably contains the lubricant relative to the first housing. For example, a lubricant-resistant wall is arranged between the first and second housings. Seals may be arranged between the first and second housings to ensure a good seal for the lubricant. The lubricant barrier protects the rotor 46, stator 45, and all electrical components from lubricant contamination, thereby preventing any short circuits.

[0063] The spindle passes through an opening in the wall between the first housing 40 and the second housing 50 to connect the rotor 46 to the transmission 55. The spindle prevents the passage of lubricant in a sealed manner. For example, the spindle is mounted in a bearing disposed in the wall between the first and second housings, the bearing being sealed against lubricant, for example including an anti-lubricant seal on at least one side of the wall.

[0064] Therefore, the first housing 40 and the second housing 50 form a housing containing the motor assembly. Motor components can be mounted within the housing without requiring a dedicated housing. The motor's electrical components, namely the stator 46, rotor 45, cables and electrical connectors required to power the motor, and in some cases, electronic circuitry, are arranged in the first housing 40. The motor's mechanical components requiring lubrication are arranged in the second housing 50. The arrangement of the second housing 50 between the first housing 40 and the crank assembly 8 allows for easy transmission of rotational motion from the rotor 46 to the crank assembly 8. The second housing 50 typically includes two orifices forming the input and output of the drive unit 70. These orifices allow the drive unit 70 to pass between components at the crank assembly 8 and the axle 77 of the rear wheel 7.

[0065] refer to Figure 6 Other openings 42 can be formed in the outer wall of the first housing 40 to allow heat generated by the motor to dissipate.

[0066] Maintenance openings 58 may be provided in the first housing 40 and / or the second housing 50. Advantageously, each opening 58 is located on an easily accessible side surface of the rear support. The maintenance opening (not shown) in the first housing provides access to the stator 45, rotor 46, cables, and any electrical connectors and / or electronic circuitry connected to the stator. The maintenance opening 58 in the second housing provides passage to the drivetrain 55, output shaft 81, and, where applicable, passage to the gearbox or continuously variable transmission. These openings allow for easy maintenance, lubrication, or repair operations on the motor. Advantageously, each maintenance opening is closed by a corresponding removable cover 57 when the bicycle is in use to prevent dirt and dust from entering the bicycle motor. A lubricant seal is typically arranged between the edge of the maintenance opening in the first housing and the cover of the first housing 40 to prevent any lubricant from entering the first housing 40. A lubricant seal 59 may also be placed between the edge of the maintenance opening 58 in the second housing and the cover 57 of the second housing 50 to prevent lubricant leakage from the second housing.

[0067] The rear support may include reinforcing structures, such as multiple ribs 60 on one or both side surfaces 36. These ribs stabilize the rear support 3 against impacts, allowing for a more refined and lightweight design of the wall. The geometry of the ribs can take into account the direction of impacts that typically occur at the rear support when the bicycle is in use. The geometry of the ribs also allows for an aesthetic design of the bicycle that can be adapted to the manufacturer's preferences. Preferably, the reinforcing structure is integrated into the side surfaces 36 of the rear support 3. Each side surface 36 may be provided with caps 31a, 31b to prevent dirt from accumulating on the reinforcing structure 60.

[0068] Reference Figure 3 and Figure 4 The rear support can be formed by two semi-stays 3a and 3b assembled on both sides of the rear wheel. This design facilitates the formation of corresponding housings 40 and 50. For example, the first housing 40 can be entirely disposed within the first semi-stay 3a, or partially disposed within both the first semi-stay 3a and the second semi-stay 3b. In this case, an anti-lubricant seal is arranged between the portion 40a of the first housing disposed within the first semi-stay 3a and the portion 40b of the first housing disposed within the second semi-stay 3b. This seal ensures an anti-lubricant seal between the first and second housings.

[0069] The second housing 50 may be partially arranged in the first half-support 3a and partially arranged in the second half-support 3b, or it may be completely arranged in only one half-support 3a, 3b.

[0070] In this configuration, when assembling the bicycle, the motor components are assembled into each housing before assembling the half-frames 3a and 3b. Then, the two half-frames 3a and 3b can be assembled. Since housings 40 and 50 are formed within the two half-frames, the assembly of the half-frames 3a and 3b allows for the closure of each housing. The half-frames 3a and 3b are assembled, for example, with screws 38.

[0071] Alternatively, the rear support 3 can be formed as a single piece. In this case, each housing includes an opening configured for inserting motor components during assembly and a cover for closing said opening. The housing can also be integrally formed in the rear support, thereby reducing the number of rear support components.

[0072] Advantageously, the rear support is formed by molding, particularly by injection molding or casting. This manufacturing method allows for the formation of a housing of precise dimensions to receive different motor components. Molding also allows for the formation of reinforcing structures, such as ribs 60 in the walls of the housing and / or vents configured for access via drive units and / or for heat dissipation. Therefore, the formation of this structure is achieved using the same method, facilitating the manufacture of the bicycle's rear support.

[0073] Advantageously, the front triangle 2 of the bicycle frame is hollow, allowing a battery to be housed therein to power the motor, for example in the slant tube 20 or tube 21 used to support the saddle, and through which brake cables and cables connecting the battery to electrical components of the motor arranged in the first housing 40 pass. In some embodiments, the front triangle 2 is also formed by molding.

[0074] The bicycle may additionally include a front suspension and / or a rear suspension. Advantageously, the front triangular member 2 is pivotally mounted on the rear support 3 about a horizontal axis 33. The pivot is located at the lower part of the front triangular member, typically at the junction between the tube supporting the saddle 21 and the base 22 of the front triangular member. This type of junction is referred to as a "single pivot".

[0075] like Figure 2 As shown, the rear bracket carries a support member 300 for the rear wheel in its rear portion. The support member 300 is designed in the form of a bracket that receives the hub of the rear wheel and includes one or more threaded holes to receive corresponding fixing screws 302.

[0076] In a particularly advantageous manner, each fixing screw 302 passes through a corresponding elliptical hole 301 in the rear support. When the screws are not tightened, the support 300 can slide between a front position and a rear position along the rectangular hole. The front position allows for mounting of the drive unit (chain or belt) between the crankset and the rear wheel, while the rear position allows for adjustment of the mechanical tension in the drive unit. Once the desired tension is achieved, the screws 302 can be tightened to hold the support 300 in the bicycle's operating position. Therefore, the need for a tensioner or other additional systems for adjusting the mechanical tension in the drive unit can be eliminated.

[0077] Obviously, any guide device other than an elliptical hole can be used, which allows each screw 302 to be guided along a trajectory that can be straight, curved, or any other suitable shape between the mounting position and the tension adjustment position.

[0078] Therefore, this bicycle design allows for the use of belts, which are quieter and more reliable drive mechanisms that require no maintenance and eliminate the need for spring-mounted tensioners, eccentric brackets, or any other tensioners of this type.

Claims

1. A system for driving the rear wheel (7) of an electric-assisted bicycle, comprising: • A rear support (3), configured to be mounted on the front triangular member (2) of the frame, the rear support (3) being adapted to support the rear wheel (7), and • An electric motor adapted to be coupled to the crank assembly (8) to rotate the crank assembly, the motor including a stator (45), a rotor (46) rotatably movable relative to the stator (45), and a transmission arranged to convert the rotational motion of the rotor (46) into the rotational motion of the crank assembly, the crank assembly being adapted to rotate the rear wheel (7) via a drive device (70). The rear support (3) includes a first housing (40) and a second housing (50), the rotor (46) and the stator (45) are arranged in the first housing (40), the transmission device is arranged in the second housing (50), the second housing (50) contains lubricant, and the lubricant is sealed relative to the first housing (40).

2. The drive system according to claim 1, wherein, The motor also includes an output shaft, which is driven to rotate by the transmission device and rotates integrally with the crank assembly (8), and the output shaft is at least partially arranged in the second housing (50).

3. The drive system according to claim 1 or 2, wherein, The transmission device also includes a gearbox (55) or a continuously variable transmission system arranged in the second housing (50), the gearbox or the continuously variable transmission system allowing selective changes in the ratio between the rotational speed of the rotor (46) and the rotational speed of the crank assembly (8).

4. The drive system according to any one of the preceding claims, wherein, The rear support (3) is obtained by molding.

5. The drive system according to any one of the preceding claims, wherein, The first housing (40) and the second housing (50) are integrally formed in the rear support (3).

6. The drive system according to any one of the preceding claims further includes a reinforcing structure (60) integrated in the wall of the rear bracket (3).

7. The drive system according to claim 6, wherein, The reinforcing structure (60) includes multiple reinforcing ribs.

8. The drive system according to any one of the preceding claims, wherein, The second housing (50) includes a pair of orifices configured to allow passage of the drive unit (70) that connects the crank assembly (8) to the rear wheel (7).

9. The drive system according to any one of the preceding claims, wherein, The first housing (40) includes one or more heat dissipation orifices (42).

10. The drive system according to any one of the preceding claims, wherein, The first housing (40) includes an opening and a removable maintenance cover arranged to close the opening.

11. An electric bicycle (100), comprising: • A frame, the frame including a front triangular member (2) that engages with a fork carrying the front wheel. • The drive system according to any one of claims 1 to 10, wherein the rear bracket (3) is mounted on the front triangular member (2), • The rear wheel (7) carried by the rear bracket (3), and • A drive unit (70) that connects the crank assembly (8) to the rear wheel (7) such that the rotation of the crank assembly (8) drives the rear wheel (7) to rotate.

12. The electric bicycle according to claim 11, wherein, The drive device (70) is a belt, chain or shaft.

13. The electric bicycle according to claim 11 or claim 12, wherein, The motor is arranged in the shaft (88) of the crank assembly (8).

14. The electric bicycle according to any one of claims 11 to 13, wherein, The front triangular member (2) includes a hollow inclined tube that receives a battery electrically connected to the motor.

15. The bicycle according to any one of claims 11 to 14, wherein, The frame is also provided with a front suspension and a rear suspension, the rear support is pivotally mounted on the front of the front triangular member in a single-pivot type, and the rear suspension is arranged between the rear support and the rear of the front triangular member.

16. The bicycle according to claim 15, comprising at least one rear wheel support mounted on the rear support (3), the support being adjustable between a mounting position of the drive unit (70) and a tensioned position of the drive unit (70), the tensioned position being positioned behind the front support relative to the mounting position.

17. The bicycle according to claim 16, wherein, The rear support (3) includes a guide device (301) such as an elliptical hole, and each support of the rear wheel is mounted on the rear support (3) via a screw (302) engaged in the guide device (301).

18. The bicycle according to any one of claims 15 to 17, without a mechanical tensioning system for the drive unit (70).

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