AU2009101006A4

AU2009101006A4 - Bicycle drive

Info

Publication number: AU2009101006A4
Application number: AU2009101006A
Authority: AU
Inventors: Andrew Paul Stuart Hamilton
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-10-02
Filing date: 2009-10-02
Publication date: 2009-11-12
Anticipated expiration: 2017-10-02
Also published as: GB2474110A; GB201015997D0

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION (Innovation Patent) Invention Title: Bicycle drive The invention is described in the following statement: 2 BICYCLE DRIVE FIELD OF THE INVENTION 5 The present invention relates to a bicycle drive system and to a bicycle incorporating such a system. BACKGROUND TO THE INVENTION 10 It is known to mount a motor, such as an electric motor, on a bicycle such that the driving power of the motor can augment the pedalling power provided by a cyclist using the bicycle. There are various known configurations for connecting an electrical motor and 15 battery to a bicycle. Typical configurations involve the use of hub motors which are mounted in the front or rear wheel hubs of the bicycles, motors that transmit power via the chains and gears of the bicycles, and direct drive motors which drive the rear wheels by physical connection to the tyres. 20 Typically, motors are 24, 36 or 48 Volt motors and are powered by battery packs of corresponding voltages. Such battery packs typically involve sealed lead acid, NiMh or standard Lithium Iron Phosphate cell technologies. Standard Lithium Iron Phosphate cells are the most advanced type of cell 25 which have been commercially used in electrically assisted bicycles. Each of these cell technologies requires a large, high capacity battery (usually 3 to 8 kg in mass), adapted to provide 250 Watt-hour of energy or greater. This often involves a plurality of cells wired in parallel, as well as in series to 30 provide the high currents required to effectively power the bicycle (usually 12 Amps at 36 Volts or more).

While the chargers for sealed lead acid batteries involve simple technology and are therefore relatively inexpensive, those required for standard lithium cells are of a more complex nature and relatively expensive. 5 Modern brushless hub motors as used in bicycles are used in conjunction with electronic controllers which control the supply of direct current (DC) from associated batteries. The controllers do this by sending appropriately timed pulses of current to the motors. The timing and duration of the pulses is varied in response to manipulation of the throttles of the bicycles to cause the motors 10 to operate at the desired speeds. Modern brushless hub motors used in this context typically have three or five high power electric wires connecting them to the controllers, while the throttles usually have four electric wires connecting them to the controllers, to transmit 15 the various electrical signals required for proper operation. Other optional sensors such as pedal sensors and brake sensors may require additional electric wiring for connection to the controllers. Because of the need for these electrical wires, in the prior art, the controllers have been permanently fixed to the bicycles, usually inside weather-proof cases. 20 Such modern brushless hub motors are typically single gear motors. As the speed of a bicycle incorporating such a motor increases, this generates increasing back-EMF (electromotive force) thus resulting in increasing electrical resistance to the motor, which in turn reduces the power output of 25 the motor. Accordingly, peak power is usually only obtained at low RPM (revolutions per minute) of the motor. Thus, as a rider of the bicycle accelerates with the assistance of the motor, power output from the motor gradually decreases to a point where the back-EMF caused by the rotation of the motor matches the forward EMF caused by the current flow through the 30 motor stemming from the associated battery, so that, at that point, the motor no longer contributes to the pedalling power provided by the rider. The prior art has various disadvantages. These include the fact that the permanent fixing of the controllers to the bicycles in weatherproof cases has 4 contributed to the weight of the bicycles, which has been particularly disadvantageous when the bicycles, especially folding bicycles, have not been used but have been transported, for example when carried by hand. 5 In addition, the permanent fixing of the controller to the bicycles has provided little deterrent against theft. This problem has been exacerbated by the use of motors that operate with standard battery voltages. This is because, due to voltages being standard, obtaining batteries of the correct voltage for use with a stolen controller has generally not been difficult. 10 Because of the relatively unsophisticated type of battery technology used and the standard voltages involved, large, heavy batteries are required, which contribute to the overall weight of the bicycles. 15 In cases where the standard Lithium Iron Phosphate battery technologies have been used as indicated above, the advantages of using such technology have been largely offset by the requirement to use more complex and expensive battery chargers. 20 The use of battery packs which have been of the same nominal voltage as the motors that they were used to power, has not derived the amount of power and torque that could be generated by the hub motors in the electrically assisted bicycle context. 25 It is an object of the present invention to overcome or ameliorate disadvantages of the prior art, or to provide a useful alternative thereto. Any discussion of the prior art in this specification is not intended as, and is not to be construed as, any admission that the prior art constitutes part of the 30 common general knowledge anywhere.

5 SUMMARY OF THE INVENTION According to a first aspect of the invention there is provided a bicycle drive system including: 5 a hub motor mounted on a hub of a wheel of a bicycle and configured to provide rotational power to the wheel, with a first plurality of electric signal transmitting wires connected to, and extending from, the motor; a throttle control mounted on the bicycle, with a second plurality of electric signal transmitting wires connected to, and extending from, the throttle 10 control; a battery pack; a motor controller electrically connected to the battery pack, with a third plurality of electric signal transmitting wires, and a fourth plurality of electric signal transmitting wires, each connected to, and extending from, the motor 15 controller; a first, high current multiple-connector electric connection plug; and a second, multiple-connector electric connection plug which is complementary to, and removably connectable with, the first plug, wherein said first and second pluralities of wires are connected to the 20 first plug and the third and fourth pluralities of wires are connected to the second plug, such that connection of the first and second plugs to each other causes the first and fourth pluralities of wires, and hence the motor and controller, to be electrically connected to each other, and causes the second and third pluralities of wires, and hence the throttle control and controller, to 25 be electrically connected to each other. In a preferred embodiment, the battery pack and motor controller are detachably fixed to each other mechanically. Preferably, there is provided a thermal insulator, preferably of plastics material, disposed between the battery 30 pack and motor controller. Preferably, the battery pack and motor controller are detachably fixed to each other by a hook and loop fastener, preferably Velcro (TM), which is preferably of plastics material and which preferably constitutes the thermal insulator.

6 In a preferred embodiment, each of the first plurality of wires and fourth plurality of wires is constituted by three wires, and each of the second plurality of wires and third plurality of wires is constituted by four wires. 5 In this case, preferably, one of the first plug and second plug is a male part of a seven-pin plug and the other of the first plug and second plug is a complementary female part of a seven-pin plug. More preferably, the first plug is a male part of a seven-pin plug 10 Preferably, each plug is a high current plug. In a preferred embodiment, the battery pack includes a plurality of cells each preferably being a Lithium Ion cell. Preferably, the battery pack includes at least twelve cells, and preferably has a weight of less than 1 kg. 15 The battery pack preferably includes twelve nano-technology Lithium Iron Phosphate (LiFePO4) cells connected in series. In a preferred embodiment, each cell is an A123 Systems (TM) High Power cell, preferably of the ANR26650M1A type incorporating Nanophosphate (TM) technology. 20 In a preferred embodiment, the cells are connected to one another in series. They are preferably adapted to provide, together, a nominal voltage of substantially 39.6 volts and preferably a capacity of substantially 91.08 Watt hours. 25 In a preferred embodiment, the controller is a brushless motor controller, which preferably has a rated voltage of 36 volts. In a preferred embodiment, the motor is one of a 100 mm and an 80 mm 30 bicycle hub motor, preferably with a rated voltage of 36 volts. In a preferred embodiment, the system includes an electrical recharging connector connected to the battery pack and adapted for connection to a recharging means for charging of the cells.

I Preferably, the system includes an electrical supplementary battery connector connected to the battery pack and adapted for connection to a complementary connector on an additional battery pack, to enable the additional battery pack 5 to be connected, preferably in parallel, to the battery pack of the system. In one preferred embodiment, the electrical recharging connector and supplementary battery connector are constituted by the same connector. 10 In a preferred embodiment, the system includes a battery charger adapted for charging a 36 volt sealed lead acid battery, the charger preferably having a charger connector which is complementary to, and connectable with, the recharging connector. The battery charger is preferably adapted for simultaneously charging all of the cells of the battery pack. 15 In a preferred embodiment, the system includes carry bag adapted to be removably suspended on the bicycle and to hold the battery pack and controller, thereby to removably suspend the battery pack and controller on the bicycle. The carry bag is preferably adapted to be mounted at or towards 20 the front of the bicycle. In a preferred embodiment, the carry bag is adapted to hold the motor controller with the battery pack secured thereto, in an upright orientation, with the controller above the battery pack. The carry bag preferably includes a openable cover which can be moved between a closed position in which it covers the controller, and an open position in which the 25 controller is uncovered. Preferably, when the cover is in the closed position, the carry bag is configured to allow a flow of air, induced by movement of the bicycle, under the cover and over the controller. According to a second aspect of the invention, there is provided a bicycle 30 incorporating a system according to the first aspect of the invention. According to a third aspect of the invention, there is provided a bicycle incorporating a hub motor, throttle control and electric connection plug, the motor, throttle control and plug constituting part of a system according to the 8 first aspect of the invention and being connectable, via a complementary plug, to other components constituting a remainder of the said system. In this specification, where reference is made to a connector being a high 5 current connector, this a connector adapted to handle 12 Amps or more of current at 40 volts. In this specification, any discussion of the prior art is not intended as, and is not to be construed as, any admission that the prior art forms part of the 10 common general knowledge in Australia or anywhere else. BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention will now be described, by way of 15 example only, with reference to the accompanying drawings in which: Figure 1 is schematic side view of a bicycle incorporating a drive system according to an embodiment of the invention; 20 Figure 2 is a schematic plan view of a combination of a battery pack, controller and connector plug forming part of the system of Figure 1; Figure 3 is a schematic front view of a female part of a seven pin plug connector forming part of the system of Figure 1; 25 Figure 4 is a schematic front view of a male part of the seven pin plug connector of Figure 3; Figure 5 is a schematic side view of details of the battery pack of Figure 2; 30 and Figure 6 is a schematic end view of the details of Figure 5.

9 DETAILED DESCRIPTION Referring to Figure 1 there is shown a bicycle 10 having a front wheel 12, a rear wheel 14, a seat 16, handle bars 18 and pedals 20. 5 Figure 1 also discloses, schematically, a bicycle drive system, generally designated 22. The drive system 22 includes a hub motor 24 mounted on the hub 26 of the front wheel 12, the motor being configured to provide rotational power to the wheel. 10 The system 22 also includes a throttle control 28 mounted on the handle bars 18. The throttle control 28 can be in the form of a rotational throttle, a lever, or of any other suitable form. 15 In addition, the system 22 includes a battery pack 30 and a motor controller 32. The battery pack 30 and motor controller 32 are detachably fixed to each other mechanically as shown in Figure 2. According to the preferred embodiment, they are secured by a hook and loop fastener 33 such as Velcro (TM). The fastener is of plastics material and serves as a thermal insulator 20 between these components to insulate the battery pack 30 from heat generated by the controller 32. The fastener 33 preferably has a minimum thickness in the order of 2 mm. The use of a detachable fastener of this type allows the battery pack 33 to be removed from the controller 32, for example in order to replace the battery pack. 25 In addition, the battery pack 30 and motor controller 32 are connected to each other electrically by wires 34 and a connection plug 35. They are held in a carry bag 36 suspended on the bicycle 10 near the front thereof. 30 The carry bag 36 is suspended on the bicycle 10 by means of a hook (not shown) or any other suitable means such that it can easily be removed from the bicycle. The carry bag 36 is a luggage bag having a main compartment 38 and a rear compartment 40 in which the battery pack 30 and controller 32 are held. The shape of the rear compartment 40 is such that the battery pack 30 10 and controller 32 are held, together, in an upright orientation, with the controller above the battery pack. The carry bag 36 includes a cover flap 41. The flap 41 is adapted to cover the 5 rear compartment 40 and hence the battery pack 30 and controller 32 held therein, and to be opened, thus exposing these components. The carry bag 36 is configured such that, when the flap 41 is in the closed position, and the bicycle is in motion, the bag permits a flow of air under the flap and over the controller 32. 10 In a preferred embodiment (not shown) the carry bag 36 has a plurality of battery and controller storage compartments. According to one preferred embodiment (not shown), the carry bag 36 has two rear compartments and two front compartments, allowing up to four battery packs connected in 15 parallel to be carried, without compromising the capacity of the main compartment 38. As can be seen in Figures 1 and 2, there are three electric wires 42 connected, to and extending from, the motor 24 and a corresponding three 20 wires 44 connected to, and extending from, the controller 32. The three wires 42 from the motor 24 terminate at the male part 46 of a high current seven-pin plug generally designated 48, while the three wires 44 from the controller terminate at the female part 50 of the seven-pin plug 48. 25 Similarly, there are four electric wires 52 connected to, and extending from, the throttle control 28, and a corresponding four wires 54 connected to, and extending from, the controller 32. The four wires 52 from the throttle control 28 terminate at the male part 46 of the seven-pin plug 48, and the corresponding four wires 54 from the controller 32 terminate at the female part 50 of the 30 seven-pin plug 48. The male part 46 of the seven-pin plug 48 has seven pins 56 and the female part 50 has seven complementary sockets 58, each for receiving a respective pin. Connection of the male and female parts 46, 50 to each other serves to 11 electrically connect the three wires 42 from the motor 24 to the corresponding three wires 44 from the controller 32, and the four wires 52 from the throttle control 28 to the corresponding four wires 54 from the controller. This, in turn, electrically connects the controller 32 to each of the motor 24 and the throttle 5 control 28. The motor 24 is either a 100 mm or an 80 mm bicycle hub motor, with a rated voltage of 36 volts. 10 The controller 32 is a brushless motor controller, also having a rated voltage of 36 volts. The battery pack 30 includes twelve, A123Systems (TM), nano-technology Lithium Iron Phosphate (LiFePO4) High Power cells (not shown), of the 15 ANR26650M1A type incorporating Nanophosphate (TM) technology. The overall weight of the battery pack 30 is less than 1 kg. The cells are connected to one another in series and are adapted to provide, together, a nominal voltage of substantially 39.6 Volts and a capacity of, or in 20 the order of, 91.08 Waft-hours. In Figures 5 and 6, there are shown details of the battery pack 30. The battery pack 30 includes two cell packs 30.1 and 30.2. Each pack 30.1, 30.2 has three pairs of cells 30.3 and 30.4 with the cells of each pair being arranged 25 axially with respect to each other. Thus each cell pack 30.1, 30.2 includes six cells. The pairs of each pack 30.1, 30.2, in turn, are arranged in a triangular configuration 30.5 (see Figure 6). The triangular configurations 30.5 of the two packs 30.1, 30.2 are the mirror image of each other. Connected to, and extending from, each arrangement of cells in each pack 30.1, 30.2 is a seven 30 pin balancing connector 30.6. Apart from other advantages of this arrangement, it facilitates accommodation of the battery packs 30.1 in the rear compartment 40.

A battery charger 62 (shown in phantom lines in Figure 2) which is adapted for charging 36 Volt sealed lead acid batteries can be connected to the battery pack 30 by means of a connection plug 64. The plug 64 corresponds to the part 35.1 of the plug 35 which connects the battery pack to the controller 32. 5 This connection plug 64 can connect with the other part 65.2 of the plug 35, to connect the charger 62 to the battery pack 30. The charger 62 has a charger connector 64 which is complementary to, and connectable with, the recharging connector 60, and is adapted for 10 simultaneously charging all of the cells of the battery pack 30 when the charger connector is connected to the recharging connector of the battery pack. The recharging connector 60 of the battery pack 30 also enables the battery 15 pack to be connected to a complementary connector 66 on an additional battery pack 68 (shown in phantom lines in Figure 2). This enables the additional battery pack 68 to be connected in parallel to the battery pack 30 of the system 22. It will thus be appreciated that the recharging connector 60 of the battery pack 30 also serves as an electrical supplementary battery 20 connector. Additional battery packs can also be connected in parallel. In a preferred embodiment, the bicycle 10 is a folding bicycle, preferably a Bromton (TM) folding bicycle. In order to adapt such a bicycle for use with the system 22, it may be necessary to replace the existing front wheel of the 25 bicycle with another wheel (namely the wheel 12, including tube and tyre, which incorporates the motor 24 as a 100 mm or an 80 mm hub motor). This in turn may require widening the front forks 70 of the bicycle 10 to accommodate the replacement wheel. For example, where the spacing between the tines of the front fork is 70 mm, this may be widened to 86 mm. 30 In addition, the modification may involve widening the dropouts (not shown) of the fork 70 to accommodate the axle (not shown) of the hub motor 24 which is wider than that of the existing front wheel of the bicycle. The modification may further involve installing the wires 42 from the motor 24 within the fork 70 of the bicycle 10 and connecting these, together with the wires 52 from the |1 throttle control 28, to the male part 46 of the seven pin plug 48. A Brompton (TM) mudguard stay and hook (not shown) may also be fitted to the hub motor axle. 5 In use, the bicycle 10 is ridden by a cyclist sitting on the seat 16. As the cyclist propels the bicycle 10 using the pedals 20, the hub motor 24 augments the driving power of the bicycle thus assisting the cyclist. The battery pack 30 together with the controller 32 are held in the bag 36 10 which is suspended on the bicycle 10, and the controller 32 is connected to the motor 24 and throttle control 28 via the seven-pin plug 48. The ability of the carry bag 36 to allow a flow of air over the controller 32 during movement of the bicycle 10 assists in cooling the controller which, 15 otherwise, may cause undesirable heating of the battery pack 30. This air flow is enabled even when the cover flap 41 is in its closed position in which it can assist in preventing the ingress of water during rainy weather. The cyclist can adjust the degree of assistance provided by the motor 24 by 20 operating the throttle control 28, which in turn operates the controller 32, and the controller in turn controls the operation of the motor. When the bicycle 10 is not needed, for example when it is parked, the controller 32 and battery pack 30 can be disconnected from the remainder of 25 the system 22 on the bicycle, by disconnecting the male and female parts 46, 50 of the plug 48. This reduces the risk that the controller 32 will be stolen. In addition it may reduce the risk that the bicycle 10 as a whole will be stolen, as the cyclist-assisting function performed by the motor 24 may be effectively negated without the battery pack 30 and the combination of the controller 32 30 and plug 50 which may be difficult to source elsewhere. The use of Lithium Ion cell technology means that the battery pack 30 is likely to be lighter, thereby contributing to the overall lightness of the bicycle. This can assist in reducing the pedalling effort of the cyclist and reducing the load on the motor 24 when the bicycle 10 is being ridden. In addition, where the 14 bicycle 10 is to be moved or carried by hand (which is likely particularly if it is of a folding type), the ability to remove the controller 32 and battery pack 30 and thereby reduce the weight of the bicycle can be beneficial. 5 The use of the nano-technology Lithium Iron Phosphate cells as described above is also advantageous as each cell is not prone to "thermal runaway" which could otherwise pose a risk to the battery pack 30 which is mounted to the controller 32. 10 The fact that the voltage produced by the battery pack 30 exceeds the nominal voltage of the motor 24 and controller 32 means that it is likely that greater power and torque can be derived from the motor. In addition, as the speed of the bicycle 10 increases, the power output from the motor 24 decreases as described above, so that the higher current through the motor 15 during acceleration of the bicycle is only temporary. This may assist in reducing the risk of overheating of the motor 24. Although the invention is described above in relation to preferred embodiments, it will be appreciated by those skilled in the art that it is not 20 limited to those embodiments, but may be embodied in many other forms.

Claims

1. A bicycle drive system including: a hub motor mounted on a hub of a wheel of a bicycle and configured 5 to provide rotational power to the wheel, with a first plurality of electric signal transmitting wires connected to, and extending from, the motor; a throttle control mounted on the bicycle, with a second plurality of electric signal transmitting wires connected to, and extending from, the throttle control; 10 a battery pack; a motor controller electrically connected to the battery pack, with a third plurality of electric signal transmitting wires, and a fourth plurality of electric signal transmitting wires, each connected to, and extending from, the motor controller; 15 a first, high current multiple-connector electric connection plug; and a second, multiple-connector electric connection plug which is complementary to, and removably connectable with, the first plug, wherein said first and second pluralities of wires are connected to the first plug and the third and fourth pluralities of wires are connected to the 20 second plug, such that connection of the first and second plugs to each other causes the first and fourth pluralities of wires, and hence the motor and controller, to be electrically connected to each other, and causes the second and third pluralities of wires, and hence the throttle control and controller, to be electrically connected to each other. 25

2. A bicycle drive system according to claim 1 wherein the battery pack includes twelve nano-technology Lithium Iron Phosphate (LiFePO4) cells connected in series. 30

3. A bicycle drive system according to claim 1 or claim 2 wherein the battery pack and motor controller are detachably fixed to each other mechanically, with a thermal insulator disposed between them. 16

4. A bicycle drive system according to any one of the preceding claims, including a carry bag adapted to be removably suspended on the bicycle and to hold the battery pack and controller, thereby to removably suspend the battery pack and controller on the bicycle, the carry bag being adapted to hold 5 the motor controller with the battery pack secured thereto in an upright orientation, with the controller above the battery pack, and including an openable cover which can be moved between a closed position in which it covers the controller, and an open position in which the controller is uncovered, wherein, when the cover is in the closed position, the carry bag is 10 configured to allow a flow of air, induced by movement of the bicycle, under the cover and over the controller.

5. A bicycle incorporating a system according to any one of the preceding claims.