Abstract:
A motorized surfboard comprises top and bottom shells. The top shell comprises recesses that may contain motors, batteries, and motor controllers. The bottom shell comprises recesses that may contain one or more impellers. The impellers may be connected to the motors by shafts that extend through passageways between recesses in the top and bottom shells. The motors may be controlled by the user with various hand, arm, or leg motions. This may be accomplished by providing an accelerometer on the user. Orientation and motion sensed by the accelerometer may be translated to motor commands and these commands may be transmitted wirelessly to the motor controllers.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/240,974 filed on Sep. 9, 2009, entitled “POWERED SURFBOARD,” which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to motor driven surfboards. 
         [0004]    2. Description of the Related Art 
         [0005]    Surfing is the sport of riding a surfboard on the face of an ocean wave towards the shoreline. Jet powered surfboards have been devised and utilized for the purpose of surfing without waves such as in lakes or other calm waters. Several types of motorized water boards in the prior art include U.S. Pat. No. 6,702,634 to Jung; U.S. Pat. No. 6,409,560 to Austin; U.S. Pat. No. 6,142,840 to Efthymiou; U.S. Pat. No. 5,017,166 to Chang; and U.S. Pat. No. 4,020,782 to Gleason. Another powered surfboard design is described in U.S. Pat. No. 7,226,329 to Railey. This device uses small electric motors to provide power while maintaining traditional surfboard performance. 
       SUMMARY OF THE INVENTION 
       [0006]    In one embodiment, a surfboard comprises a top shell comprising one or more recesses formed therein and a bottom shell coupled to the top shell, where the bottom shell also comprises one or more recesses formed therein. The recesses in the top shell extend generally toward the bottom shell, and the recesses in the bottom shell extend generally toward the top shell. A passageway connects at least one of the one or more recesses in the top shell with at least one of the one or more recesses in the bottom shell. At least one motor may be positioned in at least one of the recesses in the top shell. At least one impeller may be positioned in at least one of the recesses in the bottom shell. The impeller may be coupled to one portion of a shaft, another portion of the shaft may be coupled to the motor, and wherein the shaft extends through the passageway. 
         [0007]    In another embodiment, a method of making a surfboard comprises affixing a top shell to a bottom shell to form a surfboard body, placing at least one motor in at least one recess in the top shell, placing at least one impeller in at least one recess in the bottom shell, and coupling the impeller to the motor. 
         [0008]    In another embodiment, a system for controlling a powered surfboard comprises an accelerometer, a processor coupled to the accelerometer, and a radio transmitter coupled to the processor. The processor is configured to receive output from the accelerometer, determine motor control commands based, at least in part, on the output from the accelerometer, and transmit motor control commands to a motorized surfboard via the radio transmitter. The system may comprise a housing for the accelerometer, processor, and radio transmitter. The housing may be integrated into a glove, a wrist strap, or an ankle strap. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is an exploded view of a top shell of a surfboard showing components placed in top shell recesses. 
           [0010]      FIG. 2  is an exploded view of a bottom shell of a surfboard showing components placed in bottom shell recesses. 
           [0011]      FIG. 3  is a cutaway view of a surfboard made from top and bottom shells with power components mounted therein in accordance with one embodiment of the invention. 
           [0012]      FIG. 4  shows a detailed view of a passageway between a motor recess in a top shell and an impeller recess in a bottom shell. 
           [0013]      FIG. 5  is a perspective view of a flow housing in which the impeller may be inserted. 
           [0014]      FIG. 6  illustrates the bottom shell attached to the top shell in the region of the surfboard tail with one flow housing attached in one of the bottom shell recesses. 
           [0015]      FIG. 7  is a block drawing showing one embodiment of a drive control system, which may be used in one embodiment of the motorized surfboard. 
           [0016]      FIG. 8  is a flow chart illustrating a method for use with one embodiment of the motorized surfboard 
           [0017]      FIG. 9  is a flow a top view of one embodiment of a drive control system, which may be used in one embodiment of the motorized surfboard. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0018]    Traditionally, the sport of surfing comprises a rider (“surfer”) paddling out by lying prone on the surfboard and paddling away from the shoreline towards a point at which waves are cresting; turning to face the shoreline; paddling quickly towards the shoreline when a wave begins to crest so as to catch the wave; and riding the wave on the surfboard propelled by the wave towards the shoreline in a prone, sitting or standing position. When riding a wave, a surfer may turn the surfboard towards or away from different parts of the cresting wave depending on the preference and skill of the surfer. Subsequently, the surfer must paddle out and repeat the process of catching and riding waves. After catching and riding waves for a period of time, the surfer may ride a wave all the way to the shoreline, or may paddle in by lying prone on the surfboard and paddling towards the shoreline. Paddling out, turning, paddling quickly to catch waves can be tiring and time consuming to the surfer and can thus limit the surfer&#39;s energy and time for riding waves. Advantageous embodiments of the present invention preserve a surfer&#39;s maximum energy for riding waves rather than exhausting the surfer&#39;s energy on paddling. In addition, embodiments of the invention help a surfer catch larger and faster waves easier. 
         [0019]    The general purpose of many embodiments described herein is to provide a motorized surfboard which can be manufactured in a less labor intensive manner, has minimal problems with leakage and long term reliability. 
         [0020]    Referring now to  FIGS. 1 ,  2 , and  3 , in advantageous embodiments, a motorized surfboard comprises a top shell  102 , and a bottom shell  202 . This hollow shell construction has been recently utilized for surfboard manufacture, and represents a departure from traditional shaped foam boards. It is one aspect of the invention that this hollow shell design has been adapted to a motorized surfboard in a manner that minimizes manufacturing costs and provides structural integrity and long term reliability. 
         [0021]    The top shell  102  is illustrated in  FIG. 1 , and the bottom shell  202  is illustrated in  FIG. 2 . In  FIG. 3 , a conceptual cutaway view is provided showing how the shells mate with each other in an especially advantageous embodiment. 
         [0022]    The top shell  102  has an outer surface  104 , and an inner surface  106 . Similarly, the bottom shell has an outer surface  204 , and an inner surface  206 . To produce the complete surfboard body, the two shells are sealed together along a seam  302  that extends around the periphery of the top and bottom shells. The “outer surface” of the top and bottom shells are the surfaces that are contiguous with the surfaces exposed to the water in use (although not all of the “outer surface” of the shells is actually exposed to water as will be seen further below). The “inner surface” of the top and bottom shells are the surfaces internal to the hollow board after sealing into a hollow surfboard body. The general methods of producing surfboards with this hollow shell technique are known in the art. Currently, Aviso Surfboards (www.avisosurf.com) manufactures surfboards in this manner from carbon fiber top and bottom shells forming a hollow surfboard body. 
         [0023]    The outer surface  104  of the top shell  102  is formed with one or more recessed portions  112 , where the recessed portions extend generally toward the inner surface  206  of the bottom shell  202  when the shells are sealed together into a hollow body. The recessed portions  112  form compartments for batteries  114 , motor controller boards  116 , and motors  118 . The motors  118  are coupled to shafts  120  that extend out the rear of the motor compartment as will be explained further below. 
         [0024]    After installation of these components, the recesses can be sealed with a cover  122  that can be secured in place with adhesive such as caulking or other water resistant sealant. If desired, an internally threaded access port  124  can be provided that receives an externally threaded cover  126 . This can provide easier access than removing or cutting the adhesive on the larger cover  122 . In some advantageous embodiments, one or both of the covers  122 ,  126  are clear so that the batteries, motors, and/or other electronics can be seen when they surfboard is sealed up and in use. Another threaded plug  130  can also be provided, which can be used to ensure equal air pressures on the inside and outside of the hollow body. This feature is well known and normally utilized for hollow shell surfboards. 
         [0025]    Turning now to  FIG. 2 , the outer surface  204  of the bottom shell  202  also includes one or more recessed portions  212 , where the recessed portions extend generally toward the inner surface  106  of the top shell  102  when the shells are sealed together into a hollow surfboard body. The bottom shell  202  may also contain recesses  218  for fin boxes that accept fins  220  in a manner known in the art. The bottom shell recesses  212  are configured to accept pump housings  224 . As shown in  FIG. 3 , the pump housings  224  receive the motor shafts  120 , onto which an impeller  226  is attached. At the rear of the pump housing  224 , a flow straightener  228  may be attached. 
         [0026]    As shown in  FIG. 3 , the recessed portion  112  in the top shell and the recessed portion  212  in the bottom shell comprise walls  302  in the bottom shell and  304  in the top shell that are proximate to one another. In advantageous embodiments, these proximate walls extend approximately perpendicular to the overall top and bottom surfaces of the surfboard. In these proximate walls are substantially aligned openings, through which the motor shaft  120  extends. Thus, the motor(s)  118 , which reside in a recessed portion of the top shell, are coupled to the impeller(s) that reside in the pump housing(s) that in turn reside in a recessed portion of the bottom shell. 
         [0027]      FIG. 4  illustrates in more detail the surfaces  302  and  304  through which the motor shaft  120  extends. Typically, the motor  118  includes an integral shaft  402  of fairly short extent. This short shaft may be coupled to a longer extended motor shaft  120  with a bellows coupler  404 . These couplers  404  are commercially available, from for example, Ruland, as part number MBC-19-6-6-A. The bellows coupling  404  is advantageous because it allows for smooth shaft rotation even in the presence of vibrations and/or small deviations in linearity of the connection. The long shaft  120  then extends through a bearing  408  which has a threaded rear portion. The threaded rear portion of the bearing  408  is threaded into a threaded insert  410  that is positioned on the other side of the openings, in the recessed portion of the bottom shell. When the bearing is tightened into the insert, a water tight seal is created as the walls  302  and  304  are compressed together. It will be appreciated that the walls  302 ,  304  may directly touch, or they may remain separated, with or without additional material between. To further minimize any potential for leakage, it is possible to place washers of rubber, polymer, or the like between the insert  410  and the wall  320 , and/or between the bearing  408  and the wall  304 . 
         [0028]      FIGS. 5 and 6  illustrate the positioning of the pump housing  224  in the recessed portion  212  of the bottom shell.  FIG. 5  illustrates the underside of the pump housing  224  and  FIG. 6  illustrates a pump housing installed in a recess of the bottom shell. The pump housing  224  is basically a hollow tube for directing water up to the impeller and out the rear of the surfboard. Thus, the pump housing comprises an inlet port  502  and an exhaust port  504 . The pump housing  224  can be secured in the recess  212  in a variety of ways. The embodiment of  FIGS. 5 and 6  includes shafts  508  that are secured to each side of the pump housing. The tip  510  of the shaft  508  extends through an opening  512  in the frontward of the pump housing  224 . Referring now to  FIG. 6 , these exposed tips  510  are placed in holes  602  in the recess to secure the pump housing into the frontward portion of the recess  212 . The rear of the pump housing may comprise a wall with holes that mate with holes  616  in the bottom shell. The holes in the bottom shell may be provided with press fit threaded inserts. Screws  518  can then be used to secure the rear of the pump housing  224  to the rear of the recess  212 . 
         [0029]    It will be appreciated that the pump housing  224  can be secured in the recess  212  in a variety of ways. For example, instead of having holes in the bottom shell for screws and pins, slots and/or blind recesses can be formed in or adhesively attached to the side surfaces of the recess that engage mating surfaces on the pump housing. Such structures can also be provided with threads for engaging screw connections. As another alternative, adhesive could be used to secure the pump housing in place. 
         [0030]    Turning now to the power and control electronics and devices illustrated in  FIGS. 1 and 3 , a wide variety of power sources, motor controllers, and motors may be utilized. They can be secured in their respective recesses on metal frames and/or plates (not shown) that are secured in the recesses with adhesive and/or with fasteners such as screws to structures in the recesses integral to the side walls or adhesively secured thereto. Acceptable sources of power include a lithium battery or plurality of lithium batteries. 
         [0031]    To avoid a hard wired connection to the motor controllers  116  from a throttle control input, the motor controller  116  advantageously include a wireless receiver. This receiver can communicate with a wireless transmitter that is controlled by the surfer in order to control the motor speed. Wireless throttle controls have been used extensively, but using a throttle while surfing poses unique issues in that paddling, standing, and riding waves will interfere with a surfer&#39;s ability to easily manipulate a control mechanism such as a trigger, a dial, or the like. In one embodiment, wireless transmission circuitry can be configured to transmit electromagnetic and/or magnetic signals underwater. Because one or both transmitter and receiver can be under the surface of the ocean during much of the duration of surfing, a transmission system and protocol that is especially reliable in these conditions may be used. For example, wireless circuitry can be implemented in accordance with the systems and methods disclosed in U.S. Pat. No. 7,711,322, which is hereby incorporated by reference in its entirety. As explained in this patent, it can be useful to use a magnetically coupled antenna operating in a near field regime. A low frequency signal, e.g. less than 1 MHz, can further improve underwater transmission reliability. With this type of throttle system, an automatic shut off may be implemented, where if the signal strength between the transmitter and receiver drops below a certain threshold, indicating a certain distance between the two has been exceeded, the receiver shuts off the electric motor. This is useful as an automatic shut off if the surfer falls off the board. 
         [0032]      FIG. 7  illustrates an alternative control mechanism  680  for controlling a motorized surfboard. Control mechanism  680  has a processor  690  for coordinating the operation of the control mechanism  680 . The processor  690  is coupled to an accelerometer  700 . The accelerometer  700  measures acceleration. These measurements are communicated to processor  690 . Processor  690  may also communicate with accelerometer  700  for the purpose of initializing or calibrating accelerometer  700 . In one embodiment, accelerometer  700  is a 3-axis accelerometer and can measure acceleration in any direction. Processor  690  is also coupled to memory  710 . In one example, memory  710  is used to store patterns or profiles of accelerometer readings which have been associated with particular motor control commands. For example, memory  710  may store a pattern of accelerometer readings which has been previously associated with a command to cause the motor controller to activate the motors. The processor  690  can compare the current accelerometer  700  outputs to the previously stored profiles to determine whether the current outputs should be interpreted as a motor command. Control mechanism  680  also has a radio transmitter  720  coupled to the processor  690 . In one embodiment, radio transmitter  720  transmits information received from processor  690 , such as motor commands, to radio receiver  504 . 
         [0033]      FIG. 8  illustrates a method  740  for using control mechanism  680 , consistent with one embodiment of the invention. At step  745 , output is received from the accelerometer. In one embodiment, the output from the accelerometer may be an analog signal representative of the acceleration measured along each axis measured by the accelerometer. In another embodiment, an analog to digital converter may be used to convert the output to a digital representation of the analog signal. Alternatively, the accelerometer may be configured to output digital signals. For example, the accelerometer itself may be configured to output a digital pulse when the acceleration detected on each axis exceeds some threshold amount. 
         [0034]    After the output from the accelerometer is received, the control mechanism compares the output to pre-determined command profiles as show in step  750 . These command profiles may also be referred to as accelerometer output patterns or simply as patterns. For example, the control mechanism may store a pattern corresponding to a repeated positive and negative acceleration substantially along a particular axis. Another pattern may correspond to an isolated positive acceleration along a particular axis. The patterns of accelerometer outputs may be associated with particular commands for the motor controllers. For example one pattern may correspond to a command to activate a subset of the available motors. Another pattern may correspond to a command to activate one or more available motors with a particular duty cycle or at a particular percentage of maximum operation potential. 
         [0035]    The comparison of the current accelerometer output to the command profile results in a determination of whether the output matches a particular command profile, as shown in step  755 . In one embodiment, if the current output does not match a command profile, the output from the accelerometer is discarded and the method concludes, leaving the control mechanism to wait for more output from the accelerometer. However, if the current output does match a command profile, the control mechanism transmits the corresponding command to the motor controllers, as shown in step  760 . After the transmission, the command mechanism may again wait for additional output from the accelerometer. 
         [0036]    In alternative embodiments, the control mechanism may operate without the need for pattern comparison. For example, in one embodiment, the control mechanism may be configured to interpret accelerometer readings as a proxy for throttle control. In one embodiment, the magnitude and duration of the accelerometer output may be directly translated into magnitude and duration signals for the motor controllers. For example, an acceleration reading above a particular threshold may be interpreted as a command to activate the motors. The duration of the command may be a proportional to the duration for which the acceleration reading is received.  FIG. 9  illustrates one possible embodiment for the control mechanism  680 . In this embodiment the control mechanism is encapsulated in a package  790  which is integrated into a glove  780 . It will be appreciated by one of ordinary skill in the art that the term integrated into the glove may comprise being attached to the surface or within the structure of glove  780 . In one embodiment the package  790  is a water tight package. In one embodiment, package  790  comprises a plastic box. In another embodiment, package  790  comprises layers of fabric or other materials. Advantageously this embodiment facilitates control of the motorized surfboard while maintaining the ability of the surfer to use his hands for normal surfing activity. For example, rather than positioning one hand on throttle  620  to control the motorized surfboard, the normal motion of the surfer&#39;s hand, while wearing the glove, may be used to control the motorized surfboard. For example, it may be desirable for the motor controller to activate the motors while the surfer would normally be paddling. This may be when the surfer is paddling out or when the surfer is attempting to position himself to catch a wave. Accordingly, when the control mechanism is embed in a glove,  780 , the control mechanism may be configured to recognize the acceleration experienced by a surfer&#39;s hand during the paddling motion as a command to engage the motors. Thus, the surfer is free to use his hands for normal surfing activity while the control mechanism activates the motors when the surfer&#39;s hand motions indicate that the surfer is performing an activity which would be aided by additional motor support. Alternatively, the control mechanism may be configured to activate the motors in response to patterns which, though not necessarily surfing related, require less effort or distraction than involved in manually manipulating a throttle. For example, while riding a wave, rather than adjusting a throttle, the surfer wearing glove  780  might simply shake his hand to engage or disengage the motor. Accordingly, the surfer is able to control the motors of the surfboard with less effort and coordination than would be required to manipulate the throttle embedded in body of the surfboard. Further, the control mechanism may be configured to automatically deactivate the motors in response to a decrease in signal strength between the receiver and a transmitter encapsulated in box  790 . For example, the control mechanism may be configured to deactivate the motors when a surfer falls off of the surfboard and becomes separated therefrom. In an alternative embodiment, the packaged control mechanism  790  may also be attached to or integrated into a wrist strap of other clothing or accessory. In another embodiment, a glove  780  or other accessory or clothing may be worn on each hand and each corresponding control mechanism may control a different subset of motors in the motorized surfboard.