Abstract:
A electric motor system for supplying assistive propelling power to a bicycle, comprising: one or more drivetrains, each comprising a motor-drive shaft having a pinion with fixed drive system driving a crown and bearing assembly connected to a spindle; and a controller for executing a motor control sequence comprising: an initial state activated by a rider&#39;s start command where the motor speed is being detected for an initial period, and if the motor speed is higher than a first speed threshold continuously for a first period, then the motor is turned on to output a rider-selected torque level; a continuous motor speed detection state where the motor speed is being continuously detected, and if the motor speed falls below a second speed threshold continuously for a second period, then the motor is turned off; and the motor is turned off if a stop command from the rider is received.

Description:
CLAIM FOR PRIORITY 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 62/271,304, filed on Dec. 27, 2015; the disclosure of which is incorporated by reference herein in its entirety. 
     
    
     COPYRIGHT NOTICE 
       [0002]    A portion of the disclosure of this patent document contains material, which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
       FIELD OF THE INVENTION 
       [0003]    The present invention generally relates to electrical power assisted pedal-driven bicycles. 
       BACKGROUND 
       [0004]    Most currently available motorized bicycles have either add-on or complete designs of electric motors or petro-powered motors attached to or integrated with the basic pedal-driven bicycles. However, most of these motorized bicycles are visibly identifiable as different from conventional un-motorized bicycles. Modern bicycles have body frames of open structures formed by interconnecting tubes to keep weight down while maintaining rigid structural integrity. This makes concealing the motors, batteries, and fuel tanks a challenge. 
       SUMMARY OF THE INVENTION 
       [0005]    It is an objective of the present invention to provide a system of battery-powered electric motor propulsion for supplying assistive propelling power to conventional bicycles. It is a further objective of the present invention to provide such system with concealed and disguised components such that a motorized bicycle incorporating such system appears to be substantially similar to a conventional un-motorized bicycle. It is a still further objective of the present invention to provide such system that can be adopted in existing conventional un-motorized bicycles without significant alternation to the major components of the bicycles as an after market enhancement, or be easily incorporated into new designs of bicycles. 
         [0006]    The system of battery-powered electric motor propulsion comprises a specially designed bicycle frame, a bottom bracket, a drivetrain, and a battery power supply. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Embodiments of the invention are described in more details hereinafter with reference to the drawings, in which: 
           [0008]      FIG. 1A  shows a photograph of a typical “diamond” upright bicycle frame; 
           [0009]      FIG. 2  depicts a bottom bracket shell portion of a bicycle frame in accordance to one embodiment of the present invention; 
           [0010]      FIG. 3  depicts a bottom bracket shell portion of a bicycle frame along with bottom bracket components and drivetrain components in accordance to one embodiment of the present invention; 
           [0011]      FIG. 4  depicts portions of the bottom bracket components and a drive-side crank spindle; 
           [0012]      FIG. 5  depicts the portions of the bottom bracket components assembled to the drive-side crank spindle; 
           [0013]      FIG. 6  shows a cross-sectional view of the pinion with fixed drive system that connects the motor to the crown gear of the drivetrain; 
           [0014]      FIG. 7  shows a photograph of a battery power supply assembly in accordance to one embodiment of the present invention; 
           [0015]      FIG. 8  shows another photograph of the battery power supply assembly; 
           [0016]      FIG. 9  shows a flowchart diagram of motor control in accordance to one embodiment of the present invention; 
           [0017]      FIG. 10  shows a flowchart diagram of motor control in accordance to another embodiment of the present invention; 
           [0018]      FIG. 11  shows a photograph of an electric bicycle incorporating the system of electric motor in accordance to one embodiment of the present invention; 
           [0019]      FIG. 10  shows a side view of an electric bicycle incorporating the system of single electric motor in accordance to one embodiment of the present invention; and 
           [0020]      FIG. 11  shows a side view of an electric bicycle incorporating the system of double electric motors in accordance to one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    In the following description, motorized bicycles and systems of battery-powered electric motor propulsion for supplying assistive propelling power to conventional bicycles are set forth as preferred examples. It will be apparent to those skilled in the art that modifications, including additions and/or substitutions may be made without departing from the scope and spirit of the invention. Specific details may be omitted so as not to obscure the invention; however, the disclosure is written to enable one skilled in the art to practice the teachings herein without undue experimentation. 
         [0022]    The system of battery-powered electric motor propulsion in accordance to various embodiments of the present invention comprises a specially designed bicycle frame, a bottom bracket, a drivetrain, and a battery power supply. 
       Bicycle Frame 
       [0023]    Various embodiments of the specially designed bicycle frame in accordance to the present invention are based on the modern upright bicycle frame called the “diamond” frame.  FIG. 1  shows a photograph of a typical “diamond” frame. Resembling the shape of a diamond, the profile of “diamond” frame is made up of two triangles: a main triangle and a paired rear triangle. Referring to  FIG. 1 . The frame has a tubular structure having a head tube  101 , top tube  102 , down tube  103 , seat tube  104 , a pair of chain stays  105 , and a pair of seat stays  106 . The head tube  101  contains the headset, which is the interface with the fork. The top tube  102  connects the head tube  101  to the seat tube  104  at the top. The top tube  102  may be positioned somewhat horizontally (parallel to the ground when the bicycle frame is placed upright vertically). The down tube  103  connects the head tube  101  to the bottom bracket shell  107 . The seat tube  104  connects to and provides support to the seat at the top and connects to the bottom bracket shell  107  at the bottom. The chain stays  105  run in proximately parallel to the top tube  102  connecting the bottom bracket shell  107  to the rear fork ends. The seat stays  106  connect the top of the seat tube  104  to the rear fork ends. 
         [0024]    In a first embodiment of the specially designed bicycle frame in accordance to the present invention, the down tube and/or the seat tube are securely connected (e.g. by welding) to the bottom bracket shell on its cylindrical wall. The bottom bracket shell is an open cylinder without its bases covered. The bottom bracket shell provides one or two through-hole(s) at where the down tube and/or the seat tube are connected to the bottom bracket shell. The size(s) of these one or two top through-hole(s) approximately match the sectional width(s) of the down tube and/or the seat tube. This configuration allows the hollow interiors of the bottom bracket shell, the down tube, and/or the seat tube to be interconnected. The bottom-facing side (opposite of the down tube and/or the seat tube) of the cylindrical wall of the bottom bracket shell also has one or more through-hole(s). The openings are axially aligned with the down tube and/or seat tube in their longitudinal directions. These bottom through-hole(s) allow the insertion of electric motor and gearbox assembly(ies) of the drivetrain into the down tube and/or the seat tube through the bottom bracket shell. 
         [0025]    Shown in  FIG. 2  is a bottom bracket shell  201  that is connected to the down tube  202  and the seat tube  203  of a bicycle frame. In this embodiment, the bottom bracket shell  201  has one through-hole  204  to allow the insertion of a drivetrain electric motor and gearbox assembly from the outside through the through hole  204  and the bottom bracket shell  201  and into the interior of the down tube  202 . 
         [0026]    The down tube and/or the seat tube have one or more threaded or unthreaded through hole(s) at specific location(s) to allow screw(s) or bolt(s) to penetrate through the wall(s) of the down tube and/or the seat tube and be fasten to the inserted electric motor and gearbox assembly(ies), thus securing the electric motor and gearbox assembly(ies) inside the down tube and/or the seat tube. In addition, the down tube and/or the seat tube have one or more opening(s) on their wall(s) to allow electrical wire(s) to connect the electric motor(s) from outside of the down tube and/or the seat tube. The electrical wire(s) may connect with the battery power supply assembly and/or an electronic control circuitry. 
         [0027]    In a second embodiment of the specially designed bicycle frame, the bottom bracket shell is detachable from the main bicycle frame structure. The down tube and the seat tube are connected to a hub at their bottom ends, or arranged to have their bottom ends fixed at close proximity to each other. In all of the aforesaid configurations, the down tube and/or the seat tube are open at their bottom ends, making the interior space of the down tube and/or the seat tube accessible through their bottom end(s). In the configuration where the down tube and the seat tube are connected to a hub, the hub provides one or two opening(s) at where the down tube and the seat tube join the hub in such a way that access to the hollow interior space of the down tube and/or the seat tube through the hub is unobstructed. 
         [0028]    The detachable bottom bracket shell here is also a cylindrical drum with its the bases uncovered. The bottom bracket shell provides one or two through-hole(s) on its cylindrical wall at location(s) that can be aligned with the bottom end opening(s) of the down tube and/or the seat tube when the bottom bracket shell is attached to the hub or the bottom end(s) of the down tube and/or the seat tube. This enables the hollow interiors of the bottom bracket shell, the down tube, and/or the seat tube to be interconnected. Finally, the bottom bracket shell can be secured to the hub or to the bottom ends of the down tube and seat tube by screws, nuts and bolts, other mechanical fasteners, or welding. 
         [0029]    During assembly, the electric motor and gearbox assembly(ies) of the drivetrain are first inserted into and secured inside the down tube and/or the seat tube. In the first embodiment of the bicycle frame with a non-detachable bottom bracket shell, however, a bottom bracket housing may needed to be installed in the bottom bracket shell before the installation of the electric motor and gearbox assembly(ies). Then the bottom bracket is assembled in the bottom bracket shell. In the second embodiment of the bicycle frame with a detachable bottom bracket shell, the detachable bottom bracket shell with the assembled bottom bracket there within is attached to the bicycle frame, connecting with the bottom ends of the down tube and the seat tube. With the electric motor-gearbox drive shaft(s) extending into the bottom bracket, the position of the electric motor and gearbox assembly is adjusted so to have the electric motor-gearbox drive shaft gear pinion aligned and engaged with the crown gear teeth of the crown and bearing assembly provided in the bottom bracket, thus connecting the drivetrain to the spindle. 
         [0030]    An ordinarily skilled person in the art will appreciate that other configurations similar to those in the foregoing embodiments are possible so long the one or more electric motor and gearbox assembly(ies) can be inserted into and secured within one or more of the bicycle frame tubes and that portion(s) of the secured motor and gearbox assembly(ies) are allowed to be extended into the interior of the bottom bracket shell. 
       Bottom Bracket 
       [0031]    The bottom bracket shell is to house the bottom bracket that connects the electric motor-gearbox drive shaft to the spindle. A portion of the electric motor and gearbox assembly, which includes at least the drive shaft, is extended into the bottom bracket shell through the one or two top through-hole(s) at where the down tube and/or the seat tube are connected to the bottom bracket shell. 
         [0032]    The illustration in  FIG. 3  shows one embodiment of the bottom bracket. The bottom bracket comprises two bottom bracket cups  301 , a bottom bracket screw cap  302 , one or more  0 -rings  303 , a bearing sleeve  304 , an uni-directional thrust bearing  305 , a crown and bearing assembly  306 , one or more bearing sleeve retention screws  307 , a bottom bracket housing  110  and one or more bottom bracket cap anti-rotation screws  315 . 
         [0033]    Referring to both  FIGS. 3-5 . During the assembly of the bottom bracket, one of the bottom bracket cups  301  is attached to the bottom bracket screw cap  302  and both are ringed around a drive-side crank spindle  401 . The one or more  0 -rings  303  are inserted into the bearing sleeve  304  and the bearing sleeve  304  is ringed around the drive-side crank spindle and fitted within the bottom bracket screw cap  302 . The uni-directional thrust bearing  305  is then sleeved over the bearing sleeve  304  and fitted inside the bottom bracket screw cap  302 , followed by the crown and bearing assembly  306  with its crown gear teeth facing away from the drive crank. In other embodiments not shown in the drawings, the crown gear teeth can be facing the drive crank. Finally, the bearing sleeve retention screws  307  are screwed onto the drive-side spindle  401  to retain the bearing sleeve  104  and the other components around the drive-side crank spindle  401 . A bottom bracket housing  310  is inserted into the bottom bracket shell from one side, and the drive-side crank spindle  401  with the components are placed inside the bottom bracket housing  310  from the opposite side of the bottom bracket shell. The bottom bracket housing  310  has through-holes on its cylindrical wall that align with the through-holes of the bottom bracket shell. 
         [0034]    With the unattached end of the drive-side crank spindle  401  extending out from the bracket housing  310 , the other one of the bottom bracket cups  301  can ring around the drive-side crank spindle  401  and attach to the bracket housing  310 . In either embodiment of the bicycle frame, the electric motor and gearbox assembly is positioned to have the electric motor-gearbox drive shaft gear pinion aligned and engaged with the crown gear teeth of the crown and bearing assembly  306 . The bottom bracket screw cap  302  is secured to the bottom bracket shell by one or more bottom bracket cap anti-rotation screws  315 . 
         [0035]    Torque from the electric motor-gearbox drive shaft(s) is transferred to the crown and bearing assembly  306  and in turn to the drive-side crank spindle  401 . The uni-directional trust bearing  306  allows the torque to be applied to the spindle only when peddling and the crown and bearing assembly  306  are rotating in the same direction. 
       Drivetrain 
       [0036]    Referring again to  FIG. 3 . One embodiment of the drivetrain in accordance to the present invention provides an electric motor and an accompanying planetary gearbox coupled to the electric motor. The electric motor and planetary gearbox are encased inside a tube structure, forming an electric motor and planetary gearbox assembly  312 . The electric motor and the planetary gearbox are arranged axially inside the tube structure with a drive shaft having a pinion  312   a  extending from the electric motor and gearbox assembly in the longitudinal direction into the bottom bracket for engaging the crown gear teeth of the crown and bearing assembly  306 . In one embodiment, the drive shaft with its pinion  312   a  and the crown gear teeth of the crown and bearing assembly  306  is a set of spiral bevel gear. 
         [0037]    In one embodiment, a tube housing  308  is first inserted into the seat tube or down tube and secured by one or more tube housing screws penetrating through the seat tube or down tube. Then the central bearing insert  311  is inserted into the seat tube or down tube and secured by one or more tube housing screws penetrating through the seat tube or down tube. Finally, the electric motor and gearbox assembly  312  is inserted into the tube housing  308  through the central bearing insert  311  with the extended drive shaft  312   a  facing outward and is secured by a bearing retention nut  313 . The electric motor and gearbox assembly  312  is secured within the tube housing  308 . The tube housing  308  has horizontal parallel threads  308   a  on its external surface to clasp the down tube or seat tube housing screws protruding into the hollow interior space of the down tube or seat tube with the electric motor and gearbox assembly  312  and the tube housing  308  inserted there within. The multiple horizontal parallel threads  308   a  allow the electric motor and gearbox assembly  312  and the tube housing  308  to be fixed at different positions within the down tube or seat tube. 
         [0038]    Electrical wires for power transmission, and optionally control and data wires from the electric motor and gearbox assembly  312  pass through one or more through-holes on the down tube or the seat tube to connect to external battery power supply(ies) and/or other electronic control circuitry(ies). 
         [0039]      FIG. 6  shows the pinion with fixed drive system in accordance to one embodiment of the present invention. The pinion with fixed drive system is connected to a propulsion pinion gearhead through tapered contact fit for concentricity and grub screws to avoid rotation around the motor-gearbox drive shaft. The pinion with fixed drive system and the propulsion pinion gearhead have the same axis. This is ensured by precision tapered press fit around the motor-gearbox drive shaft. The pinion with fixed drive system can be driven in one direction only by limitation of a one-way bearing between the motor and gearbox assembly and the crank. When peddling backward unexpectedly, the pinion with fixed drive system is prevented from any damage to the propulsion pinion gearhead by limitation of the one-way bearing. The one-way bearing also eliminates drag felt by the rider while free-wheeling and places no load on the motor. The frequent interruption during peddling can generate great and abrupt momentum and counter momentum on the components, which may cause damage to the propulsion pinion gearhead. The pinion with fixed drive system and one-way bearing protect the propulsion pinion gearhead from counter momentum and eliminates drag while free-wheeling, therefore not driving the motor and the planetary gearbox in reverse. 
       Battery Power Supply Assembly 
       [0040]    In one embodiment, the battery power supply assembly comprises one or more battery pack(s). Each battery pack comprises a large cylinder and a small cylinder fitted within the large cylinder. The hollow interior space between the interior of the sidewall of the large cylinder and the exterior of the sidewall of the small cylinder is to hold battery cells in a circular arrangement with cathodes/anodes facing up and the opposite electrodes facing down. The battery cells electrodes are connected using a top and a bottom annulus shaped disks with conductive paths and wires. The wires are further extended to the center hollow interior space within the sidewall of the small cylinder, where power control electronics are housed within. Individual battery cell can be removed and replaced easily by lifting the large cylinder. 
         [0041]      FIGS. 7 and 8  show the photographs of the battery power supply assembly in accordance to one embodiment of the present invention. As can be seen in the photographs, battery cells are held within the hollow space between the interior of the sidewall of the large cylinder and the exterior of the sidewall of the small cylinder. In accordance to another aspect, circuitries of a battery management system are secured within the center space of the small cylinder. 
         [0042]    The whole battery pack battery management system circuitries cylinder arrangement can be further packaged and disguised as a water bottle attached to the seat tube or down tube with wire running from the battery pack, through the seat tube or down tube, to the electric motor encased in the tube structure. 
       Motor Control 
       [0043]    Referring to  FIG. 9 . In one embodiment, a user interface, such as an electro-mechanical actuator is provided such that the rider can control the start and stop of motor-assist (i.e. pressing an ‘ON/OFF’ button, or selecting among a gear and disengaged or neutral by pressing a ‘UP/DOWN’ button). The electro-mechanical actuator connects to the motor control circuitry via wire or wireless communication. When the rider commands to start motor-assist via the electro-mechanical actuator, the motor control circuitry caused to preload the motor with reduced torque by causing the motor to draw 500 mA from the battery power supply for the purpose of detecting the motor speed. This duration of ‘motor speed detection’ state is short, i.e. 10 seconds, and the ‘motor speed detection’ state is automatically cancelled thereafter until the rider commands to start motor-assist, or automatically repeated after a ‘wait’ period, i.e. 30 seconds. During the ‘motor speed detection’ state, if the speed of the motor reaches and maintains a ‘minimum power assist’ motor speed, i.e. 4000 RPM, or higher, the motor advances to the ‘power assist’ state. The ‘power assist’ state has three sub-states: ‘gears  1 ’, ‘gear  2 ’, and ‘gear  3 ’ that can be controlled by commanding via the electro-mechanical actuator (i.e. pressing a ‘UP/DOWN’ button). The ‘power assist’ state is permanent until: a) motor speed drops and maintains below a ‘power down’ speed, i.e. 3000 RPM, for longer than ‘power down’ state duration, i.e. 0.1 seconds; or b) the rider commands via the electro-mechanical actuator to shut off motor-assist (i.e. selecting ‘OFF’ mode, or selecting ‘DOWN’ when in gear 1, or holding the ‘DOWN’ button for more than i.e. 2 seconds to select disengaged or neutral). There is an independent current (torque) limiter that shuts off motor-assist if motor speed exceeds an overload limit, i.e. 9000 RPM. When motor-assist is shutoff or stopped, no electricity is drawn by the motor. In this embodiment, a motor speed sensor can be built-in to the motor or the motor control circuitry, providing the motor speed measurement data signal to the motor control circuitry. 
         [0044]    Referring to  FIG. 10 . In an alternative embodiment, a user interface, such as an electro-mechanical actuator is provided such that the rider can control the start and stop of motor-assist (i.e. pressing an ‘ON/OFF’ button or selecting among a gear and disengaged or neutral by pressing a ‘UP/DOWN’ button). The electro-mechanical actuator connects to the motor control circuitry via wire or wireless communication. In one embodiment, when the rider commands start motor-assist via the electro-mechanical actuator, the motor control circuitry continuously takes the output signal from a bicycle speed sensor for measurement of the actual bicycle speed in a ‘bicycle speed detection’ state. If the actual bicycle speed is maintained above a ‘minimum power assist’ speed, i.e. 5 km/h, or higher for continuously for an ‘minimum power assist speed’ duration, i.e. 10 seconds, the motor control circuitry causes the motor to draw electricity from the battery power supply and enter ‘power assist’ state. The ‘power assist’ state has three sub-states: ‘gears  1 ’, ‘gear  2 ’, and ‘gear  3 ’ that can be controlled by commanding via the electro-mechanical actuator (i.e. pressing a ‘UP/DOWN’ button). The ‘power assist’ state is permanent until: a) the bicycle speed drops and maintains below a ‘power down’ speed, i.e. 3 km/h, for longer than ‘power down’ state duration, i.e. 0.1 seconds; or b) the rider commands via the electro-mechanical actuator to shut off motor-assist (i.e. selecting ‘OFF’ mode, selecting ‘DOWN’ when in gear  1 , or holding the ‘DOWN’ button for more than i.e. 2 seconds to select disengaged or neutral). There is an independent current (torque) limiter that shuts off motor-assist if motor speed exceeds an overload limit, i.e. 9000 RPM. When motor-assist is shutoff or stopped, no electricity is drawn by the motor. In this alternative embodiment, the bicycle speed is detected by a speed sensor that can be a separate component 
         [0045]      FIG. 11  shows a photograph of an electric bicycle incorporating the system of a single electric motor in accordance to one embodiment of the present invention.  FIG. 12  shows a side view of an electric bicycle incorporating the system of single electric motor in accordance to one embodiment of the present invention.  FIG. 13  shows a side view of an electric bicycle incorporating the system of double electric motors in accordance to one embodiment of the present invention. 
         [0046]    The embodiments disclosed herein may be implemented using general purpose or specialized computing devices, computer processors, or electronic circuitries including but not limited to digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA), and other programmable logic devices configured or programmed according to the teachings of the present disclosure. Computer instructions or software codes running in the general purpose or specialized computing devices, computer processors, or programmable logic devices can readily be prepared by practitioners skilled in the software or electronic art based on the teachings of the present disclosure. 
         [0047]    In some embodiments, the present invention includes computer storage media having computer instructions or software codes stored therein which can be used to program computers or microprocessors to perform any of the processes of the present invention. The storage media can include, but are not limited to, floppy disks, optical discs, Blu-ray Disc, DVD, CD-ROMs, and magneto-optical disks, ROMs, RAMs, flash memory devices, or any type of media or devices suitable for storing instructions, codes, and/or data. 
         [0048]    The foregoing description of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to the practitioner skilled in the art. 
         [0049]    The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications that are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalence.