Patent Publication Number: US-2018036626-A1

Title: Modular drive system for skateboards

Description:
BACKGROUND 
     The present application relates generally to skateboards (including standard-length skateboards and longboards) and, more particularly, to a modular motorized drive system for skateboards. 
     A significant problem with current electric skateboards is that they cannot easily be upgraded or maintained by the user. Electric skateboards are typically sold as complete setups where the motor and electronics are permanently installed to the board. As electric vehicle technology improves, electric skateboard components like electronics and batteries can quickly become outdated. Users must generally purchase an entirely new electric skateboard to have the most up to date components. Battery packs also degrade over time and lose their charge capacity, requiring replacement. Users may also want to add a second battery pack to increase the distance they can travel without recharging the installed pack. Electric motors, which wear out over time and need to be replaced or upgraded, are also not typically replaceable by users. It would be desirable for users to have the ability to quickly and easily replace components of motorized skateboards. 
     The skateboard community is built around riders having a skateboard that fits their personality and riding style. It would be desirable for longboarders and other skateboarders to be able to quickly and easily convert their existing non-motorized skateboards to electrically powered skateboards using a motorized drive system retrofit kit. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     In accordance with one or more embodiments, a modular motorized drive system kit is disclosed for installation on a non-motorized skateboard. The kit includes at least one wheel equipped with a built in electric hub motor configured to replace a wheel of the non-motorized skateboard. The kit also includes a battery unit including a housing and one or more rechargeable batteries removably stored therein. The kit further includes a control unit including a housing and a motor controller removably stored therein. The housings of the control unit and/or the battery unit include a fastener for releasably connecting the housings to each other. The motor controller is electrically connectable with the one or more rechargeable batteries and the electric hub motor of the at least one wheel such that the motor controller can control power supplied by the one or more batteries to the electric hub motor. The kit also includes an attachment bracket for removably attaching the battery unit and the control unit to a deck of the skateboard. 
     In accordance with one or more embodiments, a motorized skateboard is disclosed having a modular drive system. The skateboard includes a deck having an upper side for supporting the rider and an opposite lower side. A front truck assembly supporting two front wheels and a rear truck assembly supporting two rear wheels is mounted on the opposite lower side of the deck, wherein at least one of the front and rear wheels is equipped with a built in electric hub motor. A battery unit includes a housing and one or more rechargeable batteries removably stored therein. A control unit includes a housing and a motor controller removably stored therein. The housings of the control unit and/or the battery unit include a fastener for releasably connecting the housings to each other. The motor controller is electrically connected with the one or more rechargeable batteries and the electric hub motor of the at least one wheel such that the motor controller can control power supplied by the one or more batteries to the electric hub motor. An attachment bracket removably attaches the battery unit and/or the control unit to the deck. 
     In accordance with one or more embodiments, a method is disclosed for retrofitting a conventional non-motorized skateboard with a modular motorized drive system. The skateboard includes a deck, a front truck assembly supporting two front wheels, and a rear truck assembly supporting two rear wheels. The method includes the steps of:
         disconnecting mounting bolts connecting one of the truck assemblies the front truck assembly to the deck of the skateboard to separate the front truck assembly from the deck;   removing at least one of the front wheels from the front truck assembly or the rear wheels from the rear truck assembly and replacing the removed wheel with a wheel equipped with a built-in hub motor;   installing an assembly comprising a battery unit, a control unit, and an attachment bracket on a rear side of the deck by placing the attachment bracket between the deck and the front-truck assembly, aligning mounting holes on the attachment bracket with mounting holes in the deck and front the truck assembly, and using mounting bolts to secure the front truck assembly to the deck and the attachment bracket; and   electrically connecting each wheel equipped with a built-in hub motor to a motor controller in the control unit.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a bottom perspective view of an exemplary skateboard equipped with a modular drive system in accordance with one or more embodiments. 
         FIG. 2  is a side view of the exemplary skateboard of  FIG. 1 . 
         FIG. 3  is a bottom plan view of the front portion of the exemplary skateboard of  FIG. 1 . 
         FIG. 4  is a bottom perspective view of the exemplary skateboard of  FIG. 1 , showing the battery unit separated from the control unit of the modular drive system. 
         FIG. 5  is an exploded bottom perspective view of the modular drive system in accordance with one or more embodiments. 
         FIG. 6  is an exploded top view of the modular drive system of  FIG. 5 . 
         FIG. 7  is a perspective view of an exemplary truck in accordance with one or more embodiments. 
         FIG. 8  is a top view of the truck of  FIG. 7 . 
         FIG. 9  is a perspective view of an exemplary attachment bracket of the modular drive system in accordance with one or more embodiments. 
         FIG. 10  is a perspective view of an alternate exemplary attachment bracket of the modular drive system in accordance with one or more embodiments. 
         FIG. 11  is a perspective view of the attachment bracket of  FIG. 10  having a control unit and a battery unit connected to the bracket in accordance with one or more embodiments. 
         FIG. 12  is a perspective view of yet another alternative attachment bracket having a control unit attached to a front portion of the bracket in accordance with one or more embodiments. 
         FIG. 13  is a perspective view of an exemplary wheel with a built-in hub motor of the modular drive system in accordance with one or more embodiments. 
         FIG. 14  is an exploded view of the wheel of  FIG. 13 . 
         FIG. 15  is a schematic block diagram illustrating components of an exemplary control unit of the modular drive system in accordance with one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments disclosed herein are directed to a modular motorized drive system for skateboards, which allows users to quickly and easily swap out electronics, battery packs, motors, and other components on their skateboards with replacement or upgraded components. Users can thereby keep their skateboards for long periods of time without the skateboards becoming outdated. The modular motorized drive system also allows users to easily convert non-motorized skateboards into motorized skateboards. The modular drive system can be mounted on most skateboards on the market using both the new and old school industry-standard truck mounting patterns. 
       FIGS. 1-4  illustrate an exemplary skateboard  10  fitted with a modular motorized drive system  12  in accordance with one or more embodiments. The skateboard  10  includes a deck  14  having an upper side for supporting the rider. A front truck assembly  16  supporting two front wheels  18  and a rear truck assembly  20  supporting two rear wheels  22  are mounted on the opposite lower side of the deck  14 . A battery unit  24  and a control unit  26  are also mounted on the lower side of the deck  14 . The drive system  12  is controlled by the rider via a wireless remote control device  54  (shown in  FIG. 15 ). 
     The battery unit  24  includes an outer housing, which holds one or more rechargeable batteries or battery packs therein. The battery unit  24  can be detached and replaced, as needed. The housing includes a battery connector for making electrical contact with battery terminals. 
     The housing of the battery unit  24  is attached to the housing of the control unit  26  in a side-by-side arrangement by means of releasable fasteners  27 .  FIGS. 1-5  show exemplary quick release fasteners  27 , each comprising a resilient pressable protruding button on opposite sides of the housing of the battery unit  24 , which can engage corresponding openings in the housing of the control unit  26 . The buttons can be pressed to disengage them from the openings, allowing the housings to be separated. 
     Various types of battery packs may be used in the battery unit  24 . By way of non-limiting example, A123 26650 LiFePo4 cells, a li-ion chemistry battery, may be used. Other sizes and form factors of batteries may also be used such as, e.g., an 18650 size battery, prismatic pouch cells, etc. 
     The control unit  26  includes an outer housing, which holds a circuit board containing various electronic components, including a motor controller, for controlling operation of the drive system  12 , as will be described further below in connection with  FIG. 15 . In one exemplary embodiment, the housing includes slots on opposite sides in the interior of the housing for slidingly receiving the circuit board. The circuit board can thereby be easily inserted or removed from the housing of the control unit  26 . 
     When the control unit  26  and the battery unit  24  are assembled, there is an electrical connection between the motor controller and the batteries or battery packs. In accordance with one or more embodiments, the skateboard has a four wheel drive system whereby all four wheels are motorized. In this embodiment, skateboard can include two separate control systems, one for each of the front and rear sets of wheels. In this embodiment, the two control systems communicate with each other through wired or wireless links. In one or more embodiments, the electrical connection that connects the positive and negative terminals of the battery pack to the positive and negative terminals of the receiving end of the first control system can also be data terminals to carry a signal from the first control unit through the battery pack to the second control unit when used in the four wheel drive system/two control unit configuration. The signal is used to carry the control input from the user to the motor controllers. In one or more alternate embodiments, the system includes separate wired connections for data and power. 
     The housing of the battery unit  24  and the housing of the control unit  26  can comprise a variety of materials including, e.g., molded plastic, carbon fiber, and aluminum or other metals (or combinations thereof). The housing of the battery unit  24  and the housing of the control unit  26  provide protection for their respective components from impacts and the environment (including exposure to liquids). 
     An attachment bracket  30  shown in detail in  FIG. 9  removably attaches the housing of the control unit  26  to the deck  14 . The attachment bracket  30  includes a plate  31  acting as a cover for enclosing the front end of the housing of the control unit  26 . The plate is connected by screws, bolts, or other fasteners to the housing of the control unit  26 . The attachment bracket  30  also includes a tongue member  42  extending from the plate. The tongue member  42  includes a set of mounting holes  44  for attachment to the deck  14  as will be described below. The attachment bracket  30  can comprise a variety of materials including, e.g., molded plastic, carbon fiber, and aluminum or other metals (or combinations thereof). 
       FIGS. 7 and 8  illustrate one example of a conventional commercially available front truck assembly  16  that can be used with the drive system  12  in accordance with one or more embodiments. (The same truck assembly can be used as the rear truck assembly  20 . The orientation of the rear truck assembly  20  may be reversed (i.e., backward facing) depending on whether or not the skateboard is a longboard.) The truck assembly  16  includes a base plate  32 , which is attached to the deck  14 , a hanger  34  pivotally engaging the base plate  32  at a pivot end, axle  36  extending laterally from the hanger  34  on which the wheels  18  are rotatably mounted, and a kingpin  38  holding the hanger  34  in place. The kingpin  38  may be tightened or loosened to adjust the turning responsiveness of the skateboard  10 . 
     The truck assembly base plate  32  includes a set of mounting holes  40  for mounting the truck assembly to the deck  14 . There are typically two standard hole patterns: new school and old school, both utilizing four holes. Six holes are shown in the base plate  32 . Of these six holes, a different set of four holes is used depending on whether the mounting is new school or old school. 
     As shown in  FIG. 9 , tongue member  42  of the attachment bracket  30  includes a set of six mounting holes  44  that correspond to and accommodate the hole patterns of both new school and old school truck assemblies. When installed, the tongue member  42  is between the truck assembly base plate  32  and the bottom of the deck  14  such that the mounting holes of the tongue member  42  and the base plate  32  are aligned with corresponding mounting holes in the deck  14 . The deck  14  is attached to the tongue member  42  and the base plate  32  with bolts extending through the respective mounting holes, and secured by nuts underneath the base plate  32 . The tongue member  42  preferably has six holes to accommodate both old school and new school standard hole patterns. 
     The tongue member  42  has a cutout  43  in the middle of it to allow for the option of “drop through” mounting of the trucks where the top plate of the truck is mounted on the top side of the board. This mounting style lowers the board for a lower center of gravity.  FIG. 10  illustrates an alternative attachment bracket  60  in accordance with one or more embodiments. The bracket  60  includes a tongue member  62  and an elongated plate  64 , on which a control unit  66  and battery unit  68  may be mounted. 
       FIG. 11  illustrates yet another attachment bracket  66 , on which a control unit  68  and battery unit  70  may be mounted. 
       FIG. 12  illustrates another exemplary attachment plate  74 , on which a control unit  76  may be mounted. 
       FIGS. 13 and 14  illustrate an exemplary wheel  18  of the skateboard  10 , which can be mounted on the axle  36  of the front truck assembly  16 . The wheel  18  includes an electric hub motor  19  incorporated therein, which directly drives the wheel  18 . The electric hub motor  19  is electrically connected by a cable  48  to the control unit  26 . The control unit  26  controls supply of electrical power from the battery unit  24  to the hub motor  19  in each front wheel  18 . 
     One exemplary process of replacing standard wheel with a hub motor wheel is as follows. The hub motor is slid over the longboard truck axle. Then a female threaded bolt is screwed over the threads on the longboard axle. The bolt is tightened to “sandwich” the motor between the truck and the bolt. Secondary securement can be provided by a set screw on the motor that tightens down on the longboard axle to resist the motor loosening when riding. 
     In the examples illustrated in the drawings, the front two wheels  18  of the skateboard  10  include electric hub motors  19  incorporated therein. In accordance with one or more alternate embodiments all four wheels of the skateboard  10  include hub motors, which are also controlled by the control unit  26 . 
     As shown in  FIG. 15 , the control unit  26  includes a controller  50 , which controls flow of current from the battery unit  24  to the hub motors  19  in the front wheels  18 . The controller  50  is connected to a wireless receiver  52 , which wirelessly receives operating signals from a wireless remote  54  operated by the skateboard user. The controller  50  controls the speed of the hub motors  19  by varying the power supplied to the hub motors  19  by the battery unit  24 . 
     The controller  50  can comprise a microcontroller, microprocessor, application-specific integrated circuit (ASIC), field programmable gate arrays (FPGA), or any general-purpose or special-purpose circuitry that can be programmed or configured to perform the functions described herein. 
     In accordance with one or more embodiments, one or more accessories  56  may also be controlled by the controller. Such accessories  56  can include, e.g., lights or audio speakers built into the skateboard  10 . The accessories  56  may also be directly controlled by the remote control device. 
     A conventional non-motorized skateboards can be retrofitted with the modular motorized drive system  12  as follows. The mounting bolts connecting the front truck assembly to the deck of the skateboard are removed to separate the truck assembly from the deck. The front wheels on the truck assembly are removed and replaced by wheels  18  equipped with built-in hub motors  19 . An assembly comprising a battery unit  24 , a control unit  26 , and an attachment bracket is placed on the rear side of the deck such that the mounting holes on the attachment bracket are aligned with mounting holes in the deck. The truck is placed on the attachment bracket such that the mounting holes on the truck are aligned with the mounting holes on the attachment bracket and the deck. Mounting bolts are then used to attach the deck to the attachment bracket  30  and the front truck assembly. The cables  48  connected to the hub motors  19  are then attached to the control unit  26 . 
     Having thus described several illustrative embodiments, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to form a part of this disclosure, and are intended to be within the spirit and scope of this disclosure. While some examples presented herein involve specific combinations of functions or structural elements, it should be understood that those functions and elements may be combined in other ways according to the present disclosure to accomplish the same or different objectives. In particular, acts, elements, and features discussed in connection with one embodiment are not intended to be excluded from similar or other roles in other embodiments. 
     Additionally, elements and components described herein may be further divided into additional components or joined together to form fewer components for performing the same functions. Accordingly, the foregoing description and attached drawings are by way of example only, and are not intended to be limiting.