Front motor driven bicycle with side mounted wheels

Abstract

A drive system for a side-mounted bicycle wheel includes a hub for mounting the side-mounted bicycle wheel; a motor drive for driving the side-mounted bicycle wheel, the motor drive including a motor and a planetary gear reduction assembly, the planetary gear reduction assembly being at least partially positioned within the hub and including one or more planetary gears; and a rotating hub bearing rotatably connecting the hub to the motor drive, wherein the rotating hub bearing is positioned laterally between the motor and the planetary gears.

Description

Background Art

[0001] State of the art electric bicycles are equipped with an electric motor that drives the front or rear wheel or even the pedals. These motors are equipped with a reduction gearbox or a chain or belt drive system that reduces the output speed of the motor shaft to best match the speed of the pedals or wheels of the bicycle when the bicycle is ridden at normal speed. In the case of a reduction gearbox with gears, a planetary arrangement of gears is most commonly used and well understood.

[0002] For e-bikes where the motor-gearbox is mounted directly to the front wheel, the motor-gearbox is mounted within the hub of the bicycle's front wheel. This hub is generally similar to a conventional non-motor front wheel hub in that it is fitted with an axle that fits into a double-legged front fork, and the hub has holes in the hub flange to accommodate the spokes of the bicycle wheel. The axle is rigidly mounted to the end of the front fork and is able to transfer torque from the motor to the bicycle fork through the connection to the central shaft, allowing the rider and bicycle to accelerate under the power of the motor.

[0003] However, some bicycles and electric bicycles have wheels that are mounted from only one side. One obvious benefit of this single-sided mounted wheel arrangement is that if the tire is flat, the user can change the tire without having to remove the wheel from the bicycle, such as must be done with a traditional double-sided mounted wheel design bicycle. However, one disadvantage of a single-sided mounted front wheel design is that there is a torsional moment on the front axle due to the cantilever mounting arrangement. Therefore, a single-sided mounted front wheel requires a front axle that is significantly larger in diameter than the axle in a traditional double-sided mounted design.

[0004] When the motor and reduction gearbox are mounted on the front wheel of a single-side mounted wheeled bicycle, it is simply not possible to mount the motor and reduction gearbox on the front wheel of a conventional double-side mounted electric bicycle front wheel hub motor only from one side, because the diameter of the through-axle is not enough to withstand the cantilever bending force. If the diameter of the axle is increased to account for the cantilever bending force, the diameter of the motor and the planetary gears and hub will become too large and the weight will become too large to be desirable and commercially unviable. This is because the sun gear of the front hub electric drive cuts into the axle, and if the axle diameter is increased, the planetary gears and ring gears of the planetary gearbox also need to increase in size to maintain the same gear reduction ratio. Some existing side mounted front wheel motor drives house the planetary gears and motor within a large diameter front axle, and mounted on the outer diameter of the axle are two rotating bearings that facilitate the rotation of the front wheel hub and wheel. The motor drive is connected to this outer hub by one end of a larger oversized shaft with a one-way bearing coupling. The limitation of this arrangement is that the sun gear, planetary gears and ring gears are required to be relatively small, and the disadvantage of this design is that the ability of these small gears to handle sufficiently high torque will be limited.

[0005] Designers can overcome this problem by using high-strength materials, however, the disadvantage of this solution is the higher noise level of the gears. Another disadvantage of these designs is that the rotary bearings mounted on the oversized shafts tend to be large, heavy and expensive relative to the cost base of the e-bike components. This is because the shaft diameter must be large enough to contain the planetary gear drive within it. This is particularly evident when the planetary gear drive is designed to have low noise, which often requires the use of plastic gears, and in order for these gears to be able to transmit sufficient torque, their diameter needs to be large enough. Therefore, existing side-mounted front motor drives can be made compact and lightweight but noisy, or quiet but large, heavy and expensive due to the need for large, oversized bearings mounted around the planetary gearbox.

[0006] Another disadvantage of existing single-sided mounted front wheel hub electric drives is that in order to maintain a minimum lateral width of the front motor drive, the distance between the two front wheel hub bearings is usually limited between the single-sided front fork mounting arm and the wheel spokes. If disc brakes are used, this distance is further limited, and the result may be a suboptimal hub bearing spacing, whereby the front wheel may have higher than acceptable runout and wobble, or require excessive precision and cost to maintain acceptable runout and wobble. Summary of the invention

[0007] According to a first aspect of the present invention, there is provided a drive system for a side-mounted wheel, comprising a wheel hub for mounting the side-mounted wheel; a motor drive for driving the side-mounted wheel, the motor drive comprising a motor and a planetary gear reduction assembly, the planetary gear reduction assembly being at least partially positioned within the wheel hub and comprising one or more planetary gears; and a rotating hub bearing, which rotatably connects the wheel hub to the motor drive, wherein the rotating hub bearing is positioned laterally between the motor and the planetary gears.

[0008] The hub bearing and shaft mounting arrangement of the present invention addresses the shortcomings of current side-mounted wheel drive electric vehicle designs. Positioning the rotating hub bearing in the area between the planetary gear system and the motor components facilitates the use of reasonably sized hub bearings, while still allowing for a sufficiently large diameter planetary gearbox design that enables the use of quiet plastic gears, compared to known arrangements that instead have rotating bearings positioned around the periphery of the planetary gearbox. This configuration takes advantage of the available space around the naturally small diameter motor pinion sun gear diameter, which also facilitates increasing the distance between the front hub bearings to provide more optimized spacing.

[0009] In use, the side mounted wheel may be connected to the hub, for example using a threaded connection or the like, such that the hub is coaxial with the axis of rotation of the wheel.

[0010] The planetary gear reduction assembly can be completely installed in the wheel hub or partially exposed.

[0011] The motor may be connected to a battery or similar power source.

[0012] Preferably, the rotating hub bearing is coaxial with the wheel rotation axis of the side-mounted wheel.

[0013] Preferably, the inner diameter of the rotating hub bearing is smaller than the outer diameter of the stator of the motor. Optionally, the outer diameter of the rotating hub bearing may also be smaller than the outer diameter of the stator of the motor.

[0014] Preferably, the inner diameter of the rotating hub bearing is smaller than the outer diameter of the planetary gear reduction assembly. Optionally, the outer diameter of the rotating hub bearing may also be smaller than the outer diameter of the planetary gear reduction assembly.

[0015] Preferably, the inner diameter of the rotating hub bearing is smaller than the outer diameter of the planetary input flange of the planetary gear reduction assembly. Optionally, the outer diameter of the rotating hub bearing may also be smaller than the outer diameter of the planetary input flange of the planetary gear reduction assembly.

[0016] Preferably, the motor drive further comprises a planetary input flange and a motor output flange coaxial with the wheel rotation axis of the side-mounted wheel, the planetary input flange and the motor output flange sharing a common interface with the inner surface of the rotating hub bearing.

[0017] Optionally, the rotating hub bearing may be a first rotating hub bearing, and the drive system may further include a second rotating hub bearing rotatably connecting the hub to the motor drive.

[0018] Preferably, the second rotating hub bearing is located on an opposite side of the planetary gear reduction assembly from the first rotating hub bearing.

[0019] According to a second aspect of the present invention, there is provided a bicycle comprising a side-mounted wheel mounted on the hub of the drive system of the first aspect.

[0020] Optionally, the side-mounted wheel can be a front-mounted wheel. Alternatively, the side-mounted wheel can be a rear-mounted wheel.

[0021] Optionally, the bicycle is a pedal-powered bicycle.

[0022] According to a third aspect of the present invention, there is provided an electric vehicle comprising a side-mounted wheel mounted to the hub of the drive system of the first aspect.

[0023] Alternatively, the electric vehicle may be an electric scooter. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Examples of the present invention will now be described in detail with reference to the accompanying drawings, in which:

[0025] Figure 1 A side view of a belt-driven bicycle with a side-mounted wheel is shown;

[0026] Figure 2 is a right side perspective view showing the front fork assembly and the front motor assembly; and,

[0027] Figure 3 Shows Figure 1 and Figure 2 A vertical cross-section of the front motor assembly. DETAILED DESCRIPTION

[0028] Figure 1 A preferred embodiment of a single side mounted front motor driven bicycle 1 having a front side mounted motor assembly 2 is shown.

[0029] Figure 2 Shows Figure 1 An alternative view of a single-sided mounted front motor driven bicycle 1 having a front single-sided cantilever fork member 3 facilitating rigid mounting of a front mounted motor assembly 2 and a front wheel brake caliper 6 to decelerate a front wheel disc brake rotor 5 rigidly connected to a front single-sided wheel assembly 4.

[0030] Figure 3 yes Figure 1 and Figure 2 A vertical cross-sectional front view of the front mounted motor assembly 2 through the front wheel rotation axis 7. The front mounted motor assembly 2 includes a front motor output housing 15 mounted to a front single-sided cantilever fork member 3 capable of receiving the front motor housing 9 by glue, press fit, screw or bolt type fasteners.

[0031] The front motor housing 9 is formed to house the front motor stator 10 and the front motor pinion outer bearing 14, which rotatably supports the front motor pinion 12, which is rigidly attached to the front motor magnet rotor 11. The interaction and control of the front motor stator 10 relative to the front motor magnet rotor 11 is well known and understood in the field of electric machines. The front motor pinion 12 is rotatably supported by the front motor pinion outer bearing 14 and the front motor pinion inner bearing 13, which is rotatably mounted to the front motor planet 25. The front motor planet carrier is in turn supported by the front motor planetary gearbox input flange 22 through the front motor planet carrier inner bearing 27. The front motor planetary gearbox input flange 22 is rigidly attached to the front motor output housing 15 by a plurality of front motor fasteners 16.

[0032] The front motor planetary gearbox input flange 22 is rigidly attached to the front motor planetary gearbox output flange 23 by a plurality of front motor gearbox output flange fasteners 24. The interface and connection between the front motor planetary gearbox input flange 22 and the front motor planetary gearbox output flange 23 may also be a threaded connection.

[0033] The nature of the engagement and assembly of the front motor output housing 15 and the front motor planetary gearbox input flange 22 is such that the front motor output housing 15 and the front motor planetary gearbox input flange 22 share a common interface received by the inner diameter of the front wheel hub inner bearing 20 .

[0034] The front motor planetary carrier 25 supports the front motor planetary gear shaft 29 and the front motor planetary gear 26 in a planetary gear arrangement to engage with the front motor pinion 12 and the front motor planetary gear box input flange 22 through the front motor planetary gear ring gear component 31, so that the output speed of the front motor planetary carrier 25 is reduced by between two and ten times relative to the input speed of the front motor pinion 12.

[0035] The material properties of the front motor planetary gear 26 are preferably plastic or a low noise composite material. The material properties of the front motor pinion 12 are ideally metal, such as stainless steel. The material properties of the front motor planetary gearbox input flange 22 can be ferrous metal or stainless steel metal or metal alloy. The construction and material properties of the front motor planetary gear ring gear component 31 can be of many different kinds, such as the front motor planetary gear ring gear component 31 is an integral part and a similar material to the front motor planetary gearbox input flange 22 and is constructed by a hobbing process, or the front motor planetary gear ring gear component 31 can be a different material from the front motor planetary gearbox input flange 22, such as plastic, and is constructed and attached to the front motor planetary gearbox input flange 22 by overmolding and keyed injection molding connection.

[0036] The front motor planet carrier 25 is further rotatably supported by a front motor planet carrier outer bearing 28, which is accommodated in the front motor planetary gearbox output flange 23. The front motor planet carrier 25 is rotatably connected to the front wheel hub outer 18 through a front motor one-way clutch 30, such as a one-way sprag clutch, so that the rotation of the front wheel hub outer 18 about the front wheel rotation axis 7 relative to the front motor planet carrier 25 is only possible in one direction.

[0037] The front single-sided wheel assembly 4 is rigidly mounted on one side to the front hub outer 18 with the front wheel assembly fastener 8. The front hub outer 18 is rotatably mounted to the front motor planetary gearbox output flange 23 via the front hub outer bearing 21, and is rigidly connected to the front hub inner 17 via the front disc rotor fastener 19 that passes through the front wheel disc brake rotor 5.

[0038] The front wheel hub inner part 17 is rotatably mounted to the front motor output housing 15 and the front motor planetary gearbox input flange 22 via the front wheel hub inner bearing 20. The front wheel brake caliper 6 is arranged around the front wheel disc brake rotor 5 in a well-known manner to provide braking force for the front single-sided wheel assembly 4.

[0039] like Figure 3 As shown, the position of the front wheel hub inner bearing 20 is generally on one side of the front motor planetary gear 26 and on one side of the front motor stator 10 and the front motor magnet rotating body 11, so that the front wheel hub inner bearing 20 is laterally positioned between the motor and the planetary gear system, with at least a portion of the motor on one side, such as the front motor stator 10, and at least a portion of the planetary gear system on the other side, such as the planetary front motor planetary gear 26 or the front motor planetary carrier 25.

[0040] The front wheel hub inner bearing 20 is coaxial with the front wheel rotation axis 7 and is located in the area between the planetary gear system and the front motor stator 10 and the front motor magnet rotating body 11, so that the inner diameter of the front wheel hub inner bearing 20 is smaller than the corresponding outer diameters of the front motor stator 10 and the front motor planetary gearbox input flange 22. In other words, the wheel hub inner bearing 20 is axially located between the front motor stator 10 and the front motor planetary gear 26, and radially located within the corresponding circumference defined by the radial outer surfaces of the front motor stator 10 and the front motor planetary gearbox input flange 22.

[0041] Positioning the front wheel hub inner bearing 20 in the area between the planetary gear system and the motor components has the above-mentioned benefit of facilitating the use of reasonably sized hub bearings while still allowing a planetary gearbox design of sufficiently large diameter to enable the use of quiet plastic gears, and also has the benefit of increasing the distance between the front wheel hub bearings to provide better spacing, compared to the known arrangement which instead has a rotary bearing positioned around the periphery of the front motor planetary gearbox input flange (i.e. radially in front of the front motor planetary gearbox input flange and substantially aligned with the front motor planetary gearbox input flange in the axial direction).

[0042] Although the above description is given for a pedal-driven bicycle having a front-mounted motor-driven wheel, alternative embodiments are contemplated in which the same motor assembly is used for other vehicles. For example, the motor assembly may be used for one or more non-pedal-driven bicycles, as a motor for a rear-mounted motor-driven wheel, or as a motor for a side-mounted front or rear wheel on an electric scooter, such as for a scooter (also known as a moped) that may have a drive system built into the rear suspension swing arm, an auxiliary vehicle for a disabled user, and / or a wheeled vehicle configured for use while upright.

Claims

1. A drive system for a side-mounted bicycle wheel, include: a wheel hub for mounting the side-mounted bicycle wheel; a motor drive for driving the side-mounted bicycle wheel, the motor drive comprising a motor and a planetary gear reduction assembly at least partially positioned within the hub and including one or more planetary gears and a rotatable planet carrier; as well as rotating a hub bearing to rotatably connect the hub to the motor drive, wherein the rotating hub bearing is positioned laterally between the motor and the planetary gear, and The wheel hub is connected to the planet carrier via a one-way clutch, so that the rotation of the wheel hub relative to the planet carrier is only possible in one direction.

2. The drive system of claim 1, wherein the rotating hub bearing is coaxial with the wheel rotation axis of the side-mounted bicycle wheel.

3. The drive system according to claim 1 or 2, wherein the inner diameter of the rotating hub bearing is smaller than the outer diameter of the stator of the motor.

4. The drive system according to claim 1 or 2, wherein the inner diameter of the rotating hub bearing is smaller than the outer diameter of the planetary gear reduction assembly.

5. The drive system according to claim 1 or 2, wherein the inner diameter of the rotating hub bearing is smaller than the outer diameter of the planetary input flange of the planetary gear reduction assembly.

6. The drive system of claim 1 or 2, wherein the motor drive further comprises a planetary input flange and a motor output flange coaxial with the wheel rotation axis of the side-mounted bicycle wheel, and wherein the planetary input flange and the motor output flange share a common interface with the inner surface of the rotating hub bearing.

7. The drive system of claim 1 or 2, wherein the rotating hub bearing is a first rotating hub bearing, and wherein the drive system further comprises a second rotating hub bearing rotatably connecting the hub to the motor drive.

8. The drive system of claim 7, wherein the second rotating hub bearing is positioned on an opposite side of the planetary gear reduction assembly from the first rotating hub bearing.

9. A bicycle, include:

4. A side mounted bicycle wheel mounted on the hub of a drive system as claimed in any preceding claim.

10. The bicycle of claim 9, wherein the side-mount bicycle wheel is a front-mount bicycle wheel.

11. The bicycle of claim 9, wherein the side-mount bicycle wheel is a rear-mount bicycle wheel.

12. A bicycle according to any one of claims 9 to 11, wherein the bicycle is a pedal-driven bicycle.

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