Bicycle with Motorised Single Leg Front Fork

Current electric bicycles are fitted with an electric motor that drives the front wheel, the rear wheel or the pedals. These motors are usually fitted with a reduction gearbox or a chain or belt drive system that reduces the output rpm of the motor shaft to optimally match the speed of the pedals or the wheels of the bicycle when the bicycle is ridden at normal speeds. In the case of a reduction gearbox with gears, the planetary arrangement of gears is most often used and is well understood.

In the case of electric bicycles with motor/gearboxes fitted directly to the front wheel, the motor/gearbox is usually mounted within the hub of the front bicycle wheel. This hub is generally similar to traditional motor-less front wheel hubs in that it is fitted on an axle suited for mounting to a double leg fork, and the hub has flanges with holes to accept the spokes of the bicycle wheel. The axle is rigidly mounted to the front fork ends and is able to transmit torque from the motor/gearbox housed within the hub to the bicycle fork to enable the rider and bicycle to proceed under motor power.

Front wheel driven electric bicycles also have an electronic controller system to manage power from the batteries to the motor/gearbox. These electronic controllers are well know and understood and are generally of the printed circuit board design and are

housed within a plastic weatherproof box which is mounted to the bicycle frame. Electric cables from a speed control mounted on the bicycle handlebar are connected to the electronic controller as are electric power cables from the battery pack and motor/gearbox.

Current front wheel driven electric bicycles have many drawbacks. Firstly, they rely on a traditional double leg front fork design to mount the front motor/gearbox system. The drawback of this mounting arrangement is that if the front tyre suffers a puncture, the entire front motor/gearbox, hub, and front wheel must be removed from the double leg fork in order to change or repair the tyre or inner tube. Front wheel electric drive hubs are generally heavy and unwieldy to move and handle. Additionally, due to the fact that torque is transferred to the front fork by the rigid mounting of the front electric drive hub axle, tools are required to undo the sturdy axle torque controlling nuts. All of this is time consuming and undesirable.

Another drawback is that due to the fact that the motor/gearbox is mounted and housed within the front hub, the diameter of current front wheel drive electric bicycle hubs is generally much larger than non-motorised bicycle hubs. This means that it is difficult or impossible to mount standard sized disk brake rotors on the hub. Disk brakes offer safer stopping of a bicycle in wet weather and the disk brake rotor outer diameter is important for optimum braking performance. With current front wheel drive

electric bicycles, fitting a disk brake system is only possible with a very large disk rotor diameter to clear the large motor/gearbox hub. This increases weight and the large diameter rotor provides less than optimal braking performance. The large diameter disk rotor means that standard disk brake callipers cannot be mounted on the standard bosses usually fitted to one leg of a double leg front fork. Consequently, additional mounting bosses for the brake calliper must be added to the double leg front fork. Furthermore, the larger diameter of the motor hub means the disk rotor mounting bolts are on a larger than usual pitch circle diameter which limits the degree to which the rotor can absorb side loads from the braking pad of the disk calliper - when used in conjunction with a single side pushed brake calliper. The result is that disk rotors on traditional front wheel drive electric bicycles can be prone to permanent bending due to side loads from the brake calliper.

Additionally, a further drawback of current front wheel drive electric bicycles is the lack of freedom of operating the bicycle with or without the motor/gearbox. Electric bicycle motor/gearboxes can be heavy and if the rider wishes to ride the bicycle without the added weight of the motor/gearbox, he or she must remove the entire front motor/gearbox wheel and fit a non-motorised front wheel. This takes a long time, requires special tools, and the rider also must have a non-motorised front wheel as a spare, which is costly and requires extra storage.

Furthermore, the location of mounting the electronic controller on current front wheel drive electric bicycles is unsatisfactory. Ideally, the electronic controller should be placed as close to the motor/gearbox and the battery as possible. This reduces losses in cables by shortening the cable length. Current front wheel drive bicycles have the mounting location of the electronic controller behind the saddle on a bicycle luggage rack or within the main frame. Due to the small size of the double leg front fork tubes, the nature of the double leg fork design does not allow the electronic controller to be fitted close to the front wheel motor/gearbox. Consequently, the electronic controller must be housed in a weather proof container which is mounted to the exterior of the bicycle frame. This can be unattractive to the user of the bicycle.

The present invention seeks to provide a solution to all of the above mentioned drawbacks of current front wheel drive electric bicycle designs by providing a single leg front fork design instead of the traditional double leg front fork designs. This will enable the rider to repair a punctured tyre or inner tube without the need to remove the wheel, because the tyre is free and open on one side for the user to remove it from the wheel without having to remove the wheel from the fork.

According to one aspect of the present invention, there is provided a front fork assembly for a bicycle, comprising a fork leg, a front wheel, an electrical controller and a motor/gearbox assembly, wherein the fork leg is tubular and includes internal guide elements to support a plate carrying the electrical controller, and wherein the fork leg has an upper end adapted to be attached to a steering tube of a bicycle frame and a lower end, a tubular lateral extension at the lower end of the fork extending to one side of the fork leg, for supporting bearing means for mounting the wheel to the fork, a motor housing open to the other side of the fork leg and coaxial with the lateral extension for removably receiving a drive motor/gearbox assembly, the motor housing communicating with the lumen of the fork leg. The arrangement is such that when the wheel and the motor/gearbox are mounted to the fork leg, a driveshaft extends from the motor/gearbox through the lateral extension to engage the wheel in a torque- transmitting relation.

Providing a single leg fork design adapted to accept the quick and easy attachment or detachment of a motor/gearbox unit from one side without the need for tools enables the rider to more readily, quickly, and easily operate the bicycle with or without the motor/gearbox. A further benefit to the rider is that the single leg fork design with the motor/gearbox mounted to it can be detached from the bicycle (as a complete sub-assembly unit) quickly, easily, safely,

and without the need for special tools. This allows for more compact storage of the bicycle if disassembled .

The single leg front fork design will have an enlarged and oversized fork leg compared to a double leg front fork design because the single leg must be strong and stiff enough to withstand the mechanical loads usually supported by two legs. The oversized fork leg allows the electronic controller to be fitted within the front fork leg, which eliminates the need for a separate outer box as the single leg fork will protect the electronics from the weather. Additionally, mounting the electronic controller within the single leg of the fork allows the electronic controller to be positioned as close to the motor/gearbox as possible.

According to a further aspect, the problem of mounting a normal sized disk brake rotor to the front wheel of a front wheel drive electric bicycle is addressed by adapting the single leg fork design to include a disk brake calliper as part of its integral structure. In the case of a cast or moulded fork leg, the calliper is integrally moulded with the lower leg structure. This eliminates the need to adapt the single leg fork to receive standard disk brake calliper mounts. The integral disk brake calliper feature makes the motorised single leg fork design lighter and more compact than the larger disk rotor designs of traditional front wheel drive electric bicycles because it does not need heavy bolts to fix the

calliper to the fork leg. Additionally, the integral calliper design provides optimum positioning for an optimum sized diameter disk rotor, thus providing optimum braking performance.

A further feature of the design is to incorporate a floating disk rotor to prevent the disk rotor from bending due to side loads from the integrated disk brake calliper.

Accordingly, an aspect of the present invention provides a bicycle having a single leg motorised front fork assembly, wherein a front wheel is rotatably mounted to one side of the fork leg, and a motor/gearbox assembly is releaseably mountable to the fork leg coaxially with the wheel from the other side.

An electronic controller is housed within the single fork leg, and the design is adapted for the quick and easy removal of the front wheel of the bicycle without the need for any tools. In one embodiment, the invention also provides for a quick release mechanism that allows quick, safe and easy detachment of the single leg motorised front fork including the motor/gearbox from the bicycle frame for easy storage.

A second aspect provides a motorised front wheel mounting assembly for a bicycle, comprising: a single-leg fork; bearings for mounting a front wheel to one side of the single-leg fork;

a motor/gearbox assembly releaseably mountable to the single leg fork and having a driveshaft engagable with a front wheel mounted to the bearings; and motor control circuitry mounted within the fork leg and adapted to supply electrical power to the motor/gearbox assembly.

A further aspect provides a front wheel assembly for a bicycle, comprising a single-leg fork; a front wheel rotatably mounted to one side of the single- leg fork; a motor/gearbox assembly releaseably mountable to the single leg fork and having a driveshaft engagable with the front wheel for the transmission of torque to the wheel; and motor control circuitry mounted within the fork leg and adapted to supply electrical power to the motor/gearbox assembly.

A preferred embodiment of the invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a bicycle fitted with a single leg motorised front fork of the invention;

Figure 2 is a perspective view showing the various features of the single leg motorised front fork of Figure 1 ;

Figure 3 is a cross sectional view of the engagement of the electronic controller and the motor/gearbox to the single leg motorised front fork, illustrating also the floating disk rotor design;

Figure 4 is an exploded perspective view showing how an electronic controller and a motor/gearbox attach to the single leg motorised front fork of the invention;

Figure 5 is a perspective view showing a detachable single leg motorised front fork;

Figure 6 is an enlarged perspective view showing the electronic controller guide rail of the single leg motorised front fork ;

Figure 1 shows a bicycle 1, comprising a frame 2 to which is attached a swinging rear arm 3. A rear wheel 4 is mounted to the rear arm 3, and a suspension unit 5 extends between the rear arm 3 and the frame 2. A saddle 6 is amounted to the frame by a seat post 7.

At the forward part of the frame 2, a steering tube 8 extends through the frame, with a single leg motorised front fork 9 and a front wheel 10 mounted to the lower end of the steering tube 8. A handlebar stem 11 extends upwardly from the steering tube 8 , and handlebars 12 are mounted to the upper end of the stem 11.

In the illustrated embodiment, the rear wheel 4 is movable relative to the frame 2 by means of the rear suspension unit 5 and rear arm 3. It is foreseen that the rear wheel 4 may alternatively be rigidly mounted to the frame, by providing the frame 2 and rear arm 3 as a rigidly connected unit. Likewise, the front fork 9 may include a telescopic fork leg, rather than the rigid fork leg illustrated in Figure 1

Figures 2 to 4 show the single leg motorised front fork assembly in more detail. The assembly comprises four main components, namely the fork 9, the front wheel 10, the motor/gearbox 13 and the electronic controller 14.

Figure 4 shows single leg front fork 9, formed at its lower end with a motor/gearbox receiving aperture 15 designed to receive a motor/gearbox 13. A rib 16 is provided within motor/gearbox aperture 15 to engage a corresponding groove 17 formed on motor/gearbox 13 when the motor/gearbox is mounted within the aperture 15, to prevent relative rotation between the motor/gearbox and the fork 9. The co-operating rib and groove 17 thus permit the transmission of torque from the motor to the front wheel 10, as will be described below.

Referring now up to Figure 3 , the front fork blade or leg 9 has a tubular extension 18 coaxial with the aperture 15, extending to the left of the fork leg 9 as seen in the Figure. The tubular extension 18

supports a pair of bearings 19, on which the front wheel hub 20 is mounted for rotation relative to the front fork leg 9. The centre of the front wheel hub 20 is formed with a recess 21 facing towards the fork leg 9.

Motor/gearbox 13 has an output shaft 22 designed to engage with and transfer torque to the recess 21 in front wheel hub 20. The engagement between output shaft 22 and front hub recess 21 may be any mechanical drive coupling arrangement, such as a non-circular driveshaft 22 engaging a non-circular recess 21, or the drive shaft 22 may be engage the recess 21 by means of a keyway, gear teeth, friction, a one way bearing clutch, rigid co-operating splines, or a slipper or Spragg clutch. The motor/gearbox 13 may be a brushless DC motor or an AC motor, mated to a reduction gearbox of the planetary type.

Extending from the side of the hub 20 adjacent to the fork leg 9 are a number of disk mounting pins 23. The mounting pins 23 are securely fixed to the hub 20, and at their free ends have enlarged magnetic heads 24. A floating disk rotor 25 is mounted on the disk pins 25, and may along the pins 25. The disk is prevented from moving past the ends of the pins by the enlarged magnetic heads 24, which also serve to retain the disk in its rest position, adjacent to the magnetic heads 24. Floating disk rotor 4 can be engaged by disc pads mounted in disk calliper 26. The disk rotor 25 is shown in a cut away view in Figure 4 , to show the

arrangement of floating disk pins 23 and the floating disk positioning magnets 24. Floating disk rotor 25 is a circular metal plate having a central circular aperture surrounded by a number of smaller openings 27 to accommodate the mounting pins 23. The central circular aperture accommodates the tubular extension 18 of the fork leg 9.

Where single front fork leg 9 is moulded or cast in construction, integrated disk calliper 26 is formed in a unified structure as part of single fork leg 9. Integrated disk calliper 26 has a disk brake lever 28 adapted to accept a traditional bicycle brake cable fixed to disk brake lever eyelet 29 and is of known and well understood mechanical or hydraulic disk brake calliper design. Floating disk pins 23 are made from a magnetic material such as steel with floating disk positioning magnets 24 are attached thereto at their free ends . The floating break this is intended for operation with a disk caliper having a fixed disk pad and a moving disk pad. The fixed disk pad is positioned to face towards the side of the disk rotor 25 remote from the fork leg 9, and the moving disk head is positioned to adjacent the face of the disk rotor nearer to the fork leg 9. When the brake is applied, the moving pad moves towards the disk brake rotor 25, and engages its surface, pushing the rotor away from the fork leg until the rotor engages the fixed brake pad, and the rotor is then gripped between the moving and the fixed brake pads. In this position, the rotor is moved slightly away from the

magnetic heads 24 of the disk mounting pins 23. When the brake is released, the moving pad retreats towards the fork leg, releasing the grip on the disk rotor. The magnetic heads 24 attracts the disk rotor back to the initial position, bringing the rotor clear of the fixed brake pad. This arrangement prevents the floating disk rotor 25 from rattling and making noise when not under a braking load. A further benefit of a floating rotor design is that the disk brake rotor is not subjected to bending by forces applied to it from the brake pads .

Figure 4 is an enlarged view showing single leg motorised front fork with the electronic controller guide rail feature 30 ready to receive electronic controller plate 31, on which the electronic control circuitry 14 is mounted. The guide rail 30 provides a groove in which an edge of the plate 31 is received. Two opposed grooves on inside surfaces of the hollow fork leg 9 engage opposite edges of the plate 31 to locate electronic controller plate 31 within the fork leg 9.

Motor/gearbox 13 has an electronic controller engagement aperture 32 designed to engage with electronic controller plate 31 of electronic controller 14. Electronic power connectors 33 extend along the surface of plate 31 from the electronic controller circuit 14 to a leading edge of the plate 31 (the lower edge as seen in Figures 3 and 4) .

Electronic controller plate 31 may be of the printed

circuit board type construction, or may be a metal plate to which the electronic controller 14 circuitry is mounted. Electronic controller 14 is fitted with battery power leads 34. Electronic controller 14 can be slid into the upper end of fork leg 9, and guided by the guide rails 30 down the length of the fork leg 9. When motor/gearbox 13 is fully engaged in aperture 15 of the fork leg 9, moving the controller plate 31 to its lowermost position engages the plate 31 in aperture 32 of the motor/gearbox 13. This engagement not only prevents axial withdrawal of the motor/gearbox 13 from the fork leg aperture 15, but also brings power connectors 33 into contact with terminals 35 of the motor/gearbox 13 to provide power to the motor.

When power is applied to the motor, torque about the axis of rotation of front hub 20 from motor/gearbox 13 will be transferred from front hub 20 to motor output shaft 22 and then to the bicycle frame 2 via motor/gearbox torque groove 17 and fork leg rib 16.

To attach motor/gearbox 13 and electronic controller 14 to the fork leg 9, motor/gearbox 13 is first inserted into motor/gearbox aperture 15 along the axis of rotation of front wheel 10, and then electronic controller 14 is slid on its plate 31 along guide rails 30 in order to engage plate 31 in aperture 32 of the motor/gearbox 13. Disassembly of motor/gearbox 13 and electronic controller 14 will be the reverse of the assembly process.

Figure 5 shows single leg motorised front fork adapted to suit mounting to a bicycle frame steering tube 8 by a fork clamp 40 and quick release lever 41. Also shown is a spring loaded drop pin aperture 42, provided in the bore passing through fork clamp 40 and dimensioned to receive steering tube 8. Quick release lever 9 is of the type of the well understood art of bicycle over-centre quick release designs, already conventionally used to secure wheels to bicycle frames, and as a seat post clamp. Operation of the leave nine selectively clamps or releases the fork clamp 40 around the steering tube 8. Bicycle frame steering tube 8 is fitted with a spring loaded drop pin 43 extending transversely through the tube 8 and having a pull ring 44 at one end. The opposing end of the drop pin 43 is resiliently urged to project out of the steering tube 8. By pulling the ring 44, the pin 43 can be moved so as to retract the opposing end of the pin 45 below the external diameter of the steering tube 8.

Fork clamp 40 is dimensioned to fit over the steering tube 8, the upper end of fork clamp 40 being provided with a recess opposite the aperture 42 to accommodate the ring end of the drop pin 43.

To mount the front fork to bicycle frame steering tube

8, spring loaded drop pin 43 is withdrawn, by pulling the ring 44, and the fork clamp 40 is then slid up the steering tube 8 until the drop pin 43 is aligned with

aperture 42 in the fork clamp. The ring 44 is then released, and drop pin 43 engages with the aperture 42. Quick release lever 41 is then removed from its open position (as shown in phantom line in figure 5) to its closed position, shown in solid line, to secure the fork clamp 42 the steering tube eight. The engagement of drop pin 43 in aperture 42 not only prevents the fork from moving axially along, or separating from, the steering tube 8, but also prevents any relative rotation of the front fork and the steering tube . The engagement ensures correct alignment between the front wheel and the handlebars mounted to the upper end of the steering tube 8.