Abstract:
An electric motorized propulsion system ( 10 ) for swimmers and divers ( 12 ) includes pair of leg-mounted propulsion units ( 14 ), each containing sealed electric motors ( 12 ), propellers ( 22 ), and housings ( 21 ), attach to the user&#39;s legs to provide thrust, manoeuvrability, and hands-fee operation. A control box ( 18 ) containing a motor variable speed control ( 54 ) is mountable at a convenient place on the swimmer&#39;s body. A battery unit, either simulating a diver&#39;s weight belt ( 16 ) or provided as a cylindrical hard pack ( 60 ) is carryable on thc back of thc swimmer. Electrical power and signal cables ( 30, 46 ) connect the control box to the battery unit and to the propulsion motor housings.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention pertains to propulsion systems for individual swimmers and divers. More specifically, it pertains to an electrically powered swimmer&#39;s propulsion system in which a motor-propeller assembly is mountable to at least one of the swimmer&#39;s legs.  
         BACKGROUND OF THE INVENTION  
         [0002]    Swimmers and divers often have need to travel longer distances in or under the water than are feasible without an external source of propulsion, whether for recreational, commercial or military purposes. An external propulsion source reduces the air consumption rate, fatigue and chance of decompression sickness for the diver. There are products available to provide powered propulsion for a diver. One kind of product is a powered water sled, a drawback of which is that it requires at least one hand to operate, making it difficult to perform certain tasks such as photography. Another troublesome characteristic of previously described propulsion arrangements is that the units can become lost if they are released when in the water. Also, it has been proposed to mount a propulsion unit to an air tank worn on the back of a scuba diver. While that approach provides propulsion, it does so in a way which does not well serve the diver&#39;s need for maneuverability.  
           [0003]    Thus, a need exists for a diver&#39;s personal powered propulsion system which can be operated in a hands-free manner, which is effective, and which enables a user to have a high degree of maneuverability in and under the water. The equipment comprising the system should be releasable by the user in the event of special need, but otherwise should be attached to the diver.  
         SUMMARY OF THE INVENTION  
         [0004]    This invention addresses the needs identified above. It provides an efficient and effective personal powered propulsion system for swimmers and divers which enables the user to have good maneuverability in and under the water and which, during use, leaves the user&#39;s hands free for the performance of desired tasks or actions.  
           [0005]    Generally speaking, the invention provides a powered propulsion device for a swimmer or a diver. A propeller and propeller drive electrical motor assembly is adapted to be releasably mounted to a leg of a swimmer. An electrical battery unit is adapted to be supported by the torso of the swimmer. A motor control is provided, as are electrical conductors which are connectible between the motor control, the battery unit, and the propeller motor assembly. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    The above-mentioned and other features and components of the invention are set forth in the following description of illustrative embodiments of the invention, which description is presented with reference to the accompanying drawings in which:  
         [0007]    [0007]FIG. 1 is a top plan view of a diver equipped with a personal propulsion device;  
         [0008]    [0008]FIG. 2 is an enlarged view, partially in cross-section which shows a propeller and drive motor assembly and how it can be releasably connected to a lower leg of a diver;  
         [0009]    [0009]FIG. 3 is a perspective view of a battery unit wearable by a diver in the manner of a belt;  
         [0010]    [0010]FIG. 4 is a rear elevation view of a motor control component of the propulsion device;  
         [0011]    [0011]FIG. 5 is a view showing another form of battery unit for the propulsion device.  
         [0012]    [0012]FIG. 6 is an end view of the structure shown in FIG. 5. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]    [0013]FIG. 1 shows a personal propulsion device  10  according to this invention as it may be worn or carried in use by a diver  12  or a swimmer. The diver may be a scuba diver equipped with an open circuit air breathing system which typically includes one or two compressed air tanks  13  borne by use of a suitable harness, on the back of the diver. The diver may be a free diver, i.e., one which does not carry an air supply. A user of this propulsion device may be a snorkel diver/swimmer.  
         [0014]    Propulsion device  10  is comprised principally by one or, more preferably, two propeller and propeller motor assemblies  14  (FIG. 2), a battery unit  16  (FIG. 3) and a manually operable motor control  18 . As shown in FIG. 2, each motor assembly  14  includes an electric motor  20  which is contained in a sealed, water-tight housing  21  which can be cylindrical. A propeller  22  is located outside housing  21  adjacent the rear end of the housing. The propeller is affixed to a rotatable shaft  23  which extends from the housing through redundant shaft seals (not shown) of any suitable kind. Motor  20  can be a brushless DC motor, such as an Aveox 27/39/4 motor which can operate at high speed, i.e., a speed higher than the speed at which propeller  22  is designed to operate. To enable the propeller to be driven at a rotational rate which is lower than that of the motor, shaft  23  can be an output shaft of a speed reducing gearbox  24  which can be located in the rear interior of housing  21  and which has the shaft of motor  20  as its input. The gearbox can be an Aveox gearbox having an input-to-output speed ratio of 4.4:1. The propeller can be about  3{fraction (1/4)} inches in diameter with a pitch of  3 inches; such propellers are available and often are used in model racing boats. The normal operating rate of the motor can be around 20,000 rpm, and the propeller turns rate can be on the order of 4500 rpm or so. Consistent with the performance desired in device  10 , other combinations of motors, propellers and gearboxes can be used.  
         [0015]    Motor  20  can be provided for variable speed operation. To that end, a motor speed controller  26  can be provided in the forward interior of housing  21  with its output terminals coupled directly to the input terminals of motor  20 . By placing speed controller  26  in housing  21 , a simpler electrical connector set  27 , say a three terminal set as opposed to a more costly connector set having as many as eight terminals, can be used to connect a cable  30  to housing  21 , as compared to the alternate instance of locating the electronic motor speed controller in control unit  18 . The forward end of motor housing  21  can be streamlined, as shown in FIG. 2, and can carry one moiety  28  of the electrical connector set  27 . The other cooperating moiety  29  of that connector set can be carried at the end of a waterproof multi-conductor electrical cable  30  which can connect at its other end to control unit  18 . Alternatively, cable  30  can extend, in a watertight manner, through the forward end of housing  21  for connection inside the housing of its conductors to the terminals of controller  26  or of motor  20 , as desired. Direct connection of the cable conductors to controller  26 , rather than via connector set  27 , is preferred. A suitable motor speed controller  26  can be an Aveox SL-18 controller.  
         [0016]    Propeller  22  preferably is located inside a protective open cage  32  which is affixed to the rear end of motor housing  21 . The presence of the cage around the propeller protects the propeller from contacting the body of a user, or of anything (such as a swim fin) worn by the user, during operation of the propeller. If desired in an appropriate instance, the portion of the protective cage radially adjacent the propeller blades can be defined as a shroud of a Kort nozzle; an appropriate instance could be one in which it is planned that the propeller be operated predominantly at a characteristic constant turns rate.  
         [0017]    As shown in FIG. 2, motor housing  21 , with the propeller carried by it, is adapted by other components of assembly  14  to be mounted in a releasable manner to a leg, preferably a lower leg, of diver  12 . Those other components of the assembly can include a flexible sheath-like base  34 , a mounting plate  35  and a bracket  36  coupled between the motor housing and plate  35 . Base  34  can be a modification of a conventional sheath for a diver&#39;s knife. Base  34  can have upper  37  and lower  38  strap and buckle arrangements of known kind and design which enable the base to be releasably strapped to the lower leg of a diver. In a preferred base  34 , the leg engaging straps are equipped, at and adjacent their free ends, with Velcro hook material and pile material pieces which afford precise control over the girth encompassed by the straps as secured about a diver&#39;s leg. Other forms of strap securement arrangements can be used. The upper and lower strap and buckle arrangements  37 ,  38  can be located at the opposite ends of a flexible body  39  of the base.  
         [0018]    Mounting plate  35  of assembly  14  can be a flat, comparatively rigid and strong member, such as a sheet of carbon fiber reinforced composite material. Plate  35  can be coupled to base  34  by snugged straps  40  secured to the base and passing through slots (not shown) located in the corners of the plate. Bracket  36  can be in the form of a length of upwardly open channel having its web abutting the mounting plate and the edges of its flanges engaged with the exterior of the motor housing. The motor housing, the bracket and the mounting plate can be secured together by screws  42  extending through the mounting plate and the bracket into threaded engagement with the motor housing. In such manner, the motor housing can be securely made a part of the motor assembly which can be mounted to a diver&#39;s leg.  
         [0019]    As shown in FIG. 1, propulsion device  10  preferably includes a pair of propeller and motor assemblies in accord with the foregoing descriptions. The two motor assemblies can be strapped to the diver&#39;s legs as shown, with each assembly connected electrically to a master motor control  18  carried by the diver at his/her waist or at the diver&#39;s torso.  
         [0020]    [0020]FIG. 3 depicts a belt-like battery unit  16  for propulsion device  10 . The battery unit includes an elongate flexible housing  44  which can be defined as a pouch formed of waterproof trilaminate fabric closable by a waterproof zipper (slide fastener). Inside the housing  44  can be a plurality of rechargeable batteries, such as 20 1.2V NiMH (nickel metal hydride) F cell batteries suitably interconnected to each other, as in series. The battery set is connected in turn, inside the housing, to the conductors of a waterproof multi-conductor cable  46  which extends through a watertight seal in the housing to motor control  18 . At its end opposite from housing  44 , cable  46  can terminate at one moiety  47  of a suitable water-tight electrical connector, the other moiety  48  of which is mounted to a motor control enclosure  49 . So that the belt-like battery unit can be secured around the waist of a diver, it can carry at its ends a pair of flexible straps  50 ,  51 , one ( 50 ) of which in turn carries a releasable clasp or buckle  52  with which the other strap ( 51 ) is releasably engagable. The straps and buckle can be like those commonly found as components of a diver&#39;s weight belt. Because it has substantial mass, battery unit  16  can be worn in the place of and instead of a weight belt.  
         [0021]    [0021]FIG. 4 is a rear elevation view of master motor control  18 . It includes a water-tight enclosure  49  to which, as at a side thereof, are mounted watertight electrical connector moieties  28  (preferably two of them) and  48  via which cables  30  and  46  from one or two propeller and motor assemblies  14  and a battery unit can be connected. Within enclosure  49  is a switch which controls ON and OFF states of device  10  and also the speed at which motors  20  are operated. A manually engagable rotatable actuator knob  54  can be mounted to the enclosure for operation by the diver. Knob  54  can operate a potentiometer located within the enclosure and which can include the ON/OFF switch function at one end of its range of operation. As noted above, while enclosure  49  can include the variable speed controlling electronics for motors  20 , it is preferred that the motor speed control circuitry for each motor be placed in the respective motor housing  21 .  
         [0022]    Enclosure  49  is adapted for mounting on one of belts  50 ,  51  of battery unit  16 , or on a separate belt or strap carried either around the diver&#39;s torso or on a wetsuit worn by the diver. To afford such mounting capability, a pair of loops are defined on the rear face of enclosure  49  through which the belt or strap can pass. A shown in FIG. 4, those loops can be defined by respective ones of a pair of metal straps or brackets  55  the ends of which are secured to the enclosure but which, between those ends, are spaced from the enclosure surface. Thus, because control  18  is carried by the diver at a location where actuator  54  is readily accessible, the operation of device  10  can be initiated or terminated, and the turns rate of propellers  22  can be set, from time to time as needed with the diver&#39;s hands being free for other activities at other times.  
         [0023]    The mounting of the propellers and their drive motors on the legs, preferably the lower legs above the ankles, of the diver is consistent with efficient propulsion of the diver who is pushed through the water. When a diver propels himself by use of swim fins, the diver also is pushed through the water by thrust applied to the body via the legs. Also, divers are familiar with, and reflexively rely upon, leg motions to maneuver in the water. The placement of the thrust units  14  on the lower legs of the diver enables the diver to maneuver by use of those familiar leg motions.  
         [0024]    [0024]FIG. 5 shows another battery unit  60  useful in the practice of this invention. Battery unit  60  is comprised by a rigid, sealed, preferably cylindrical housing  61  inside which is disposed an array of plural batteries. For example, 21 1.2V NiMH F or M cells can be disposed in housing  61  in three layers of 7 cells each disposed in a hexagonal array and electrically interconnected to each other. A wet pluggable bulkhead connector passes the battery leads to control unit  18  via a cable  62 . The batteries are rechargeable, and a relief valve  63  in the housing wall allows excess gas pressure due to battery recharging to vent from the housing. A similar pressure relief valve can be included in the structure of battery unit  16  if desired.  
         [0025]    Battery unit  60  can be carried by a diver as an additional component of an air tank arrangement in a scuba diving rig. A way to mount the battery unit  60  to a pair of scuba air tanks is shown in FIG. 6. Alternatively, housing  61  can be equipped with its own harness to enable battery unit  60  to be carried on the back of a diver who elects to dive without use of scuba equipment.  
         [0026]    The separability of the major components of device  10 , as via the disconnectible electrical connectors described above, makes it possible for a spent battery unit to be replaced by a fresh battery unit while the diver is in or under the water. Such battery unit changes can be planned events, or they can occur in response to an emergency.  
         [0027]    Personal propulsion devices according to this invention enable divers to travel faster and farther than they can travel in comparable time without such devices. Divers can operate submerged more productively without becoming physically tired, a circumstance which enhances diver safety.  
         [0028]    The foregoing descriptions of different embodiments of this invention have been presented illustratively, by way of example, not as an exhaustive catalog of the forms and arrangements by which the invention can be practiced or implemented. Variations and modifications of the structures and procedures described can be practiced or made without departing from the fair scope and content of the invention.