Abstract:
A pneumatic spear gun has a stock supporting a barrel. The gun uses compressed gas to power a spear having movable vanes that slide along the shaft to become fixed at the base of the spear to rotate the spear and stabilize trajectory. The compressed gas is stored in a high pressure tank in the forearm of the gun. The tank also has a breathing regulator and mouthpiece. There is a gas handling system between the tank and the barrel for providing multiple single shots and regulating the flow of expanding gases.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to the field of spear fishing. The invention also includes features useful for underwater emergencies or extending dive time. 
       BACKGROUND OF THE INVENTION 
       [0002]    Spear fishing is probably one of the oldest forms of fishing. With the advent of self contained underwater breathing apparatus (SCUBA), divers were able to remain in the underwater habitat to search out and see their prey. The power driving the spear has evolved from the hand-held spear through the Hawaiian sling with resilient bands to compressed gases, such as C02 or air. The spear guns using compressed gases are less cumbersome, require less effort, and permit more rapid firing than the earlier devices. 
         [0003]    Most of the guns are not equipped with a sighting system for improved accuracy. Since the range to the target is usually fairly short, the diver merely points and shoots. 
         [0004]    In general, the spear guns are muzzle loaded and have multiple barrels for multiple shots without reloading. The spears fired by the guns may be tethered to the gun or diver or may be untethered. The use of a tether is determined by either the type of fish being hunted or the locale. Tethered spears are desirable in reef fishing to retrieve the spear and/or the fish from restricted areas too small for a diver to enter. Some of the conventional spear guns have a safety mechanism, while other guns do not have safeties. 
         [0005]    Kenaio, U.S. Pat. No. 4,019,480, discloses a pneumatic spear gun with a mechanical safety that physically blocks the movement of the trigger when in the safe position. 
         [0006]    U.S. Pat. No. 4,660,315 discloses a spear gun that uses the diver&#39;s breathing gas as the source of power. Obviously, the number of shots taken directly reduces the underwater time of the diver. Further, the dive tank must be modified to provide another valved outlet to the tank and any malfunction of that valve could lead to the depletion of the diver&#39;s air. 
         [0007]    Ekstrom, U.S. Pat. No. 5,086,749, teaches a C02 powered gun using a hollow spear that is telescoped over a tubular barrel shaft. The compressed gas is released near the forward end of the barrel and the shaft serves to guide the spear as it is fired. 
         [0008]    U.S. Pat. No. 5,595,166 to Schmidt III et al discloses a double barreled spear gun with improved accuracy. Each spear fired by the gun may be untethered or is tethered with a fixed or spooled length tether. The gun may be side loaded rather than muzzle loaded. The muzzles are adapted to break away from the remainder of the gun. The spear is powered by resilient bands released by the trigger associated with the barrel being fired. Each trigger has a safety mechanism or lock. 
         [0009]    Horlock, U.S. Pat. No. 6,170,477, discloses a pneumatic spear gun in which the spear acts as a compressing piston in the barrel as it is loaded into the firing position. The gun also has a sealed pneumatic chamber containing air that is compressed by a manual pump forcing sea water against a movable chamber wall. 
         [0010]    What is needed in the art is a pneumatic spear gun having a small tank of highly compressed gas with a system to isolate and reduce the pressure for each shot including a regulator which may also be used by the diver. The spear gun has increased accuracy provided by a sighting system and spears with movable vanes for stabilized trajectory. 
       SUMMARY OF THE INVENTION 
       [0011]    Disclosed is a pneumatic spear gun that employs compressed gas to power a spear. The spear has movable vanes that slide along the shaft to become fixed at the base of the spear to rotate the spear and stabilize trajectory. The compressed gas is stored in a high pressure tank in the fore arm of the gun. The tank also has a breathing regulator and mouthpiece. There is a gas handling system between the tank and the barrel for providing multiple single shots and regulating the flow of expanding gases. 
         [0012]    Accordingly, an objective of this invention is to provide a spear gun having a source of highly compressed gas connected to a barrel by a pressure control system that automatically reduces the pressure and permits multiple shots. 
         [0013]    It is a further objective of this invention is to provide an ergonomically shaped spear gun for accurate aiming without interference with breathing equipment. It is also an objective to provide laser sighting to improve accuracy of the spear gun. 
         [0014]    It is still another objective of this invention to provide breathable gas in the source of highly compressed gas and a regulator to permit breathing of that source of gas. 
         [0015]    It is yet another objective of this invention to provide a safety mechanism to prevent inadvertent discharge of the spear gun by actuation of the trigger, alone. 
         [0016]    It is another objective of this invention to provide a spear which cooperates with the spear gun to improve trajectory and accuracy. 
         [0017]    Other objectives and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawing wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of the specification and include exemplary embodiments of the present invention and illustrate various objectives and features thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a side perspective of the spear gun; 
           [0019]      FIG. 2  is a top view of the spear gun; 
           [0020]      FIG. 3  is a side view, partially in section, of the spear gun; 
           [0021]      FIG. 4A  is an enlarged sectional view of the firing mechanism and safety of the spear gun; 
           [0022]      FIG. 4B  is a sectional view of  FIG. 4A  showing trigger movement; 
           [0023]      FIG. 5A  is a top detail sectional view of the safety in position to fire the left barrel with right barrel safe; 
           [0024]      FIG. 5B  is a top detail sectional view of the safety in safe position for both barrels; 
           [0025]      FIG. 5   c  is a top detail sectional view of the safety in position to fire the right barrel with the left barrel safe; 
           [0026]      FIG. 6A  is a partial sectional view of the barrel with a spear in place; 
           [0027]      FIG. 6B  is a perspective of a spear of this invention with the transitional position of the vanes in phantom lines; 
           [0028]      FIG. 7  is a perspective of the spear with tether ring and vanes; and 
           [0029]      FIG. 8  is an end view, partially in section, of the spear and vanes of this invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    Although the invention will be described in terms of a specific embodiment, it will be readily apparent to those skilled in this art that various modifications, rearrangements and substitutions can be made without departing from the spirit of the invention. The scope of the invention is defined by the claims appended hereto. 
         [0031]    Now referring to the drawings, the spear gun  10  of the instant invention resembles a field gun in that it is composed of a stock  11  with a butt  12  and a forearm. The stock supports at least one barrel  13  along the upper surface but, as shown, there are two barrels  13  and  13 ′. Also, as shown, the barrels are side-by-side but could be oriented as an over-and-under double barrel. The butt  12  is joined to the forearm by a breech section of the stock in which the trigger  17  is mounted protected by a trigger guard  16 . The stock  11  is ergonomically formed to permit the gun to be sighted, by the diver, without interference with breathing equipment. A high pressure tank  19  is mounted in the fore arm of the stock  11 . A high pressure line  26 ,  27  connects the tank  19  with the closed end of the barrel to provide power to launch the spear  14 . A laser light source  29  is mounted in the front end of the fore arm to provide target acquisition in pointing the spear gun. The laser light is powered by batteries, not shown. 
         [0032]    The stock is made of wood, preferably, though other materials are a matter of choice. It is desired that the stock has positive buoyancy such that the entire weapon has neutral buoyancy underwater for ease of carrying and deployment. The front end of the fore arm also has a cavity  31  to house a stored tether  30 . 
         [0033]    In normal operation, the spear gun is carried with a spear  14  in the barrel or two spears  14 ,  14 ′ in the barrels  13 ,  13 ′. The spear  14  has a sharpened leading end with or without a barb. The barb  60  may be fixed or pivoting, as shown, on the spear shaft. The spear is of a length to extend beyond the barrel, approximately 6 inches. 
         [0034]    Mounted on the breech portion of the stock is a safety  18  which, in the safe position, prevents firing of the spear even though the trigger is pulled. In the double barreled gun, the safety  18  has a three-way position to fire either barrel or neither, as shown in  FIGS. 3 ,  4 A, and  5 A-C. The safety is in the form of a rotary valve between high pressure lines  26  and  27  connecting the trigger mechanism and the barrel. 
         [0035]    The high pressure tank  19  is the source of power for launching the spear with a velocity sufficient to penetrate most game fish within range. The range is dependent on the diving depth and ambient pressure. The tank  19  fits smoothly in the fore arm of the spear gun and may contain various gases, with compressed air being preferred, at a pressure of approximately 3,000 to 5,000 psi. The tank has a conventional breathing regulator  20  connected to one outlet. The regulator  20  includes a refill valve and a visual pressure gauge. The regulator  20  has a mouthpiece  21  to allow the diver to breathe from the tank. 
         [0036]    The tank  19  has a second outlet connected to the barrel(s) for propelling a spear. The second outlet has a high pressure line  26  that includes a high pressure regulator  22  connected to a flow fuse  23 , an accumulator  24 , the trigger  25  and the safety  18  thence through high pressure line  27  to the closed end(s) of the barrel(s). The high pressure regulator  22  is as Model 1247, marketed by Aqua Environment Corporation. The small piston type regulator has one outlet and operates with an inlet pressure of approximately 6,000 psi and an adjustable outlet pressure of 200-1,000 psi. It is self venting when the outlet pressure exceeds set pressure by 20-40%. For example, the outlet pressure for this spear gun may be set at 1,000 psi re of 1,200 to 1,400 psi. 
         [0037]    The outlet of the regulator  22  is connected to the inlet of the pressure fuse  23 , shown in  FIG. 3 . The pressure fuse  23  is a flow limiter that prevents damage to the accumulator  24  through uncontrolled filling. The pressure fuse may be a device similar to Fuse Model 443 marketed by Aqua Environment Corporation. The pressure fuse  23  has an inlet with a spring biased valve and an outlet connected to the inlet of the accumulator  24 . The inlet pressure may be approximately 6,000 psi and the nominal flow rate to close the valve may be adjusted, e.g., a flow rate of 80 cfm at 5,000 psi can be adjusted downwardly. This provides a smooth graduated closing of the outlet of the fuse as the accumulator  24  fills for a shot. The fuse provides for a small leakage to keep the pressure in the accumulator at the set system pressure. As an alternate to the fuse, a simple restrictor may be used in the line. 
         [0038]    The accumulator  24  is a pressure reservoir with a capacity necessary for launching a spear with a force of 1,000 to 1,500 psi. The accumulator outlet is connected to the trigger valve  25 , shown in  FIGS. 4A and 4B . 
         [0039]    The trigger valve  25  has a restriction plate  50  with an aperture  51  separated from the valve  52  by a spring  53 . The valve  52  has a valve stem  54  extending through the valve seat  55  to engage the trigger  17 . As the trigger  17  pivots about trigger pin  56 , the valve stem  54  moves the valve  52  away from valve seat  55  to open the high pressure line  26  from the accumulator  24  to the safety  18 . If the safety is in the all safe position, nothing happens but if the safety is set to fire a barrel the compressed gas enters the barrel to launch the spear. The spring biased restriction plate  50  cushions the explosive escape of the compressed gas. 
         [0040]    As shown in  FIGS. 4A and 6A , the expanding gas is vented into the barrel(s)  13  between the closed end and the trailing end of the spear(s)  14  through high pressure line  27 . The trailing end of the spear has an enlarged portion  39  which may be integrally formed or in the form of a grommet attached about the shaft. The enlarged portion acts as a piston to slide through the barrel and propel the spear. The enlarged portion has a cooperating locking mechanism  38  fixedly attached on the shaft. The locking mechanism may take one of several forms, such as a projection or detent. A tether ring  40  loosely encircles the shaft of the spear  14  between the enlarged end and the barb  60 . The spear may be used with or without the tether ring. A tether  30  may be connected to the ring by any suitable connector, such as a knot, clip etc., and a length of the tether may be stored in the cavity  31 . In front of the tether ring  40 , guiding vanes  32  encircle the spear shaft. The vanes  32  have a tubular body with equally spaced wing-like projections  33 ,  34 ,  35 , and  36  extending therefrom. The wings have a pitch or twist relative to the longitudinal axis of the shaft of the spear resulting from the base of the wings set at an angle, other than parallel, to the longitudinal axis of the tubular body. The tubular body of the vanes has a cooperating lock portion  37  on the rear of the vanes. 
         [0041]    To load the gun, a spear is inserted into a barrel  13 . Underwater the barrel is filled with water. To accomplish the seating of the spear, the barrel must be vented through a bleed valve. The bleed valve  60  is mounted in the high pressure line  26 , shown in  FIG. 4A , and has a selector knob  61  which is turned between an open and closed position. In the closed position, the high pressure line  26  is uninterrupted through the valve. In the open position, the high pressure line is blocked and the barrel  13 , line  27 , safety  18  are open to the ambient pressure through outlet  62 . This permits expulsion of the fluid between the rear of the spear and the end of the barrel. Additionally, the safety must be switched to the barrel being loaded to provide an open pathway between each barrel and the outlet  62  when the valve  60  is open. 
         [0042]    As the enlarged end of the spear is inserted into the muzzle of the barrel, the tether ring and the vanes contact the stock or barrel and will slide toward the sharpened end of the spear to be disposed as shown in  FIG. 1 . In use, the target will be illuminated by the laser, the safety will be turned to select a barrel and the trigger will be pulled. When the spear is launched by the expanding gas entering the barrel, the spear accelerates through the tether ring and vanes. As the vanes are carried through the water by the spear, they begin to rotate about the barrel and ultimately come to rest against the enlarged portion of the spear. Continued rotation will result in the cooperating lock mechanisms of the vanes and the enlarged portion becoming positively engaged so that the spear will rotate thereby stabilizing the trajectory. 
         [0043]    A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrated embodiment but only by the scope of the appended claims.