Patent Publication Number: US-6341993-B1

Title: Motorized swim fin

Description:
The present invention relates to underwater personal propulsion devices, specifically to a hands-free personal propulsion device which pushes an underwater diver or swimmer through the water, and enables personal control of direction and speed through an aquatic environment with minimum or no use of hands and maximum turning agility, without the restriction of cumbersome back-worn devices. 
     BACKGROUND OF THE INVENTION 
     Underwater swimming and diving is a popular sport and hobby which has gained increasing popularity throughout the world. Since underwater diving time is generally limited by the amount of air which can be carried by the diver, and the amount of air consumed by a diver is related to the amount of energy a diver expends, there is generally a significant limitation in the amount of geographic area which a diver can traverse during an underwater diving experience. 
     Various devices have been developed to aid the transport of a diver through the aquatic environment, generally being bulky devices or vehicles which the diver must ride or otherwise grasp which pulls the diver in the direction desired. Such devices are typically bulky and heavy, require skillful hand guidance by the diver, and once the diver reaches his destination must be tended, monitored or otherwise cared for, thus limiting the diver&#39;s freedom of independent activity once he has arrived at his destination. 
     One important aspect of the diving experience is the close viewing and hands-on manipulation of objects which may be found or seen in the underwater environment. Typically, a diver desires and even needs complete freedom of movement during such experience, and the need to closely monitor or be tethered to a propelling device can be distracting and very limiting to the experience. Losing sight and/or contact with a propelling device in a murky underwater environment can result in loss of the device and/or wasted time and/or air trying to relocate the device. 
     The prior art is replete with various proposed improvements to underwater transport devices. U.S. Pat. No. 4,700,654 discloses an embodiment of a motorized propulsion device comprising a motor, a battery, and control switches which are contained in a water-tight housing and connected to a propeller. The housing is attached to the swimmer&#39;s forearms and the control switches may be operated by the swimmer&#39;s fingers. The device appears to be effective in providing a forward propulsion from the elbows of a swimmer, but limits both hand movement and arm motion of the swimmer by increasing weight and adding bulk. 
     U.S. Pat. No. 3,422,787 discloses an embodiment of an underwater propulsion system comprising a housing strapped between the calves of the swimmer&#39;s legs that contains an electric motor and a propeller, a belt disposed about the swimmer&#39;s waist attached to which are several wet cell storage batteries, and a waterproof cable that connects the batteries to the motor. This device appears to severely restrict a swimmer&#39;s mobility as the swimmer&#39;s legs are bound together by the housing of the propelling device. 
     U.S. Pat. No. 3,635,188 discloses an embodiment of an underwater propulsion device comprising a pair of structural housings that are attached one to the underside of each foot of a swimmer so as to point downward from about the arch of the foot, each housing containing a motor and a propeller. The motors in these units are coupled to at least one power supply carried by the swimmer on a belt worn about the waist. As with the previous patent, the device is effective in propelling a swimmer but requires an unnatural steering technique in which an unusual flexure of the knees and torso of a swimmer appear to be required to steer. The use of a battery belt and power supply cables running the length of the swimmer&#39;s legs could interfere with myriad other diving apparatus. 
     The devices of the above prior art disclosures appear to be inconvenient to the user, restricting the swimmer to cumbersome propulsion devices that require significant limitations in bodily movement, and/or added weight. In each instance they appear to diminish a swimmer&#39;s agility and restrict the types of bodily movement that many tasks involved in swimming and diving may require. 
     An object of the present invention is to provide an underwater propelling device which can be conveniently operated by an underwater swimmer. 
     Another object of the invention is to provide an underwater propelling device which can provide convenient directional changes by hands-free or minimum hand movement. 
     Another object of the invention is to provide an underwater propelling device which is conveniently non-interfering with the diving experience and self-tending when not being used. 
     A still further object of the invention is to provide an underwater propelling device which closely simulates natural human underwater diving techniques. 
     These and other objects of the invention will be apparent from the following description of the invention. 
     SUMMARY OF THE INVENTION 
     Swim fins are generally considered standard equipment for underwater divers and swimmers and the technique of their use in propelling the diver in the diving experience is generally considered natural in that like walking, it is generally quickly adopted to become a natural activity without thought. Swim fins generally comprise a generally flat, thin flexible paddle extending from a shallow foot well configured to secure the fin to the wearers foot. The thin paddle exaggerates the width and length of the toe portion of the foot to approximate that of a rear fin. The foot well is configured to enable secure mounting of the fin to the foot while generally maximizing forward and rearward flexure of the wearers ankle so as to provide maximum agility to the diver as he propels himself forward using a swimmers kick. 
     In its broadest form, the present invention comprises the combination of a propelling device and a modified swim fin. In the modified swim fin of the invention, the foot well of the swim fin is modified from enabling generally unrestricted flexure of the ankle to restricted flexure of the ankle, while the paddle of the swim fin is modified to comprise a generally cylindrical shape extending along about its longitudinal centerline, defining an interior passageway having openings thereto at opposite ends for the forced propulsion of water therethrough. 
     In a preferred embodiment, the foot well of the swim fin comprises a boot arrangement, wherein the boot surrounds the foot and extends above the ankle of the wearer, sufficiently tightened around the ankle to resist forward and rearward flexure of the foot at the ankle to less than about 75% of normal. 
     In one embodiment, the swim fin is formed from an elastomeric compound, straps, snaps or like means are provided to enable secure attachment of the boot to the ankle and foot of the wearer. 
     The paddle is connected to the foot well of the swim fin, at about adjacent the toe of the boot. The swim fin comprises a generally longitudinally extending tubular passageway, having an inlet arranged adjacent about the toe of the boot and having an outlet arranged at about the remote end of the paddle. Wherein the tubular passageway comprises means for forcing fluid entering the inlet of the passageway through the outlet thereof. 
     In a preferred embodiment of the invention, the means for forcing fluid comprises a power driven rotatable shaft having at least one propeller arranged to forcibly push fluid entering the inlet of the passageway through the outlet thereof. 
     In a further preferred embodiment of the invention, the rotatable shaft is powered by an electric motor in electrical circuitry with a power supply. In a particularly preferred embodiment, the electric motor is variable and/or multiple speed, the power supply is remote from the swim fin, and switching means controlling the motor, is in electrical circuitry therewith. 
     In a further preferred embodiment, the inlet to the tubular passageway comprises a means for preventing the intake of vegetation, small fish, and the like into the passageway. In a particularly preferred embodiment, mesh screens are arranged at about the intake to the passageway, and the outlet from the tubular passageway is spaced inward from the remote end of the paddle. 
     It should be understood that the present invention contemplates multiple further diverse configurations and arrangements for forcibly pushing fluid and propelling a swimmer that are in accord with the spirit of the invention wherein propulsion is assisted by forcing fluid through modified swim fin means. Thus, for example, the method for the intake of fluid through the inlet and propulsion of fluid through the outlet may comprise jet means. The paddle may comprise a plurality of inlets and outlets enabled to allow an alternate flow of water through the passageway rather than the preferred embodiment of the invention. These and other embodiments of the invention will be apparent from the following detailed description of the invention. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     The nature and mode of operation of the present invention is more fully described in the following detailed description of the accompanying drawings. 
     FIG  1  is an exploded perspective view of a motorized swim fin of the invention. 
     FIG. 2 is a sectional plan view of the motorized swim fin of FIG. 1 taken along about line  2 - 2 ′. 
     FIG  3  is a sectional plan view of the motorized swim fin of FIG. 1 taken along about line  3 - 3 ′. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1-3, therein is depicted a preferred embodiment of a modified swim fin device of the invention, wherein boot  10  comprises toe end  10   a  and heel end  10   b . Securing straps  11  are located at about boot  10  so as to secure boot  10  to the foot and ankle of the wearer. Paddle  12  is illustrated as integrally formed to boot toe end  10   a  and arranged to define a generally cylindrical interior passageway “B” generally surrounding rotatable shaft  13  laying along about centerline A-A′. 
     Paddle  12  is illustrated as exaggerating the length and width of the toe portion of the foot to form a swimmer&#39;s fin, and comprises an inlet  14 , which is located at about boot toe end  12   a  as an inlet to passageway “B”, and outlet  15  which is located at about remote end of passageway “B”. Mesh filter  20  is arranged about inlet  14  to screen the intake of vegetation and the like into passageway “B”. 
     Motor  16  may be variable and/or multi-speed and is attached to about the interior of boot toe end  10   a  within paddle  12  located within passageway “B” and arranged to drive rotatable shaft  13  such that shaft  13  rotates axially along about centerline A-A′. Propeller  17  is radially center mounted onto rotatable shaft  13  such that the propeller blades are about perpendicularly situated to the shaft. Propeller  17  is located between inlet  14  and outlet  15  and secured to shaft  13  arranged to enable pushing fluid entering through inlet  14  along passageway B out through outlet  15 . 
     Motor  16  is connected through electrical circuitry  26  to wet cell storage batteries  20  in housing  19 . Variable power supply switch  21  is in electrical circuitry among the storage batteries and the motor to enable and disable the motor as desired by the wearer so as to drive rotatable shaft  13  and create a forward propulsion for the swimmer by forcing fluid through outlet  15 . In functional operation, the arrangement of power supply housing  19  and switch  21  is configured to enable the greatest comfort and flexibility to the swimmer and it is contemplated that housing  19  and switch  21  may be attached to the swimmer at any convenient location by securing locking straps  22 , attached at about power supply housing  19 , and locking strap  23  attached at about variable switch  21 .