US2900972A

US2900972A - Underwater spear gun

Info

Publication number: US2900972A
Application number: US611716A
Authority: US
Inventors: De Loss L Marsh; Stanley C Butler
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-09-24
Filing date: 1956-09-24
Publication date: 1959-08-25
Anticipated expiration: 1976-08-25

Description

Aug- 25, 1959 DE I ss L. MARSH l-:TAL 2,900,972

UNDERWATER SPEAR GUN 2 Sheets-Sheet 1 Filed Sept. 24, 1956 ma? www N n\ 7 .s 1MM. M m ...N 0m 5 m 0 y s m Q n QN x wN 1.. Illl |u\\ S Nw W... la 1-||||| WWMWM H Q a, n

Aug. 25, 1959 DE Loss L. MARSH rs1-AL 2,900,972

UNDERWATER SPEAR GUN Filed sept. 24, 195s 2 Sheets-Sheet 2 INVENTORS 0:1055 .4. MnefH BY 5MM if C wzie A Tram/5K5 United States Patent O UNDERWATER SPEAR GUN De Loss L. Marsh, Hayward, and Stanley C. Butler, San Lorenzo, Calif.

Application September 24, 1956, Serial No. 611,716

6 Claims. (Cl. 124-13) This invention relates to underwater spear guns, and particularly those adapted for use in the support of underwater sport fishing.

Various types of spear guns have been developed for underwater spear fishing, with the propulsive means for the spears being generally Classifiable as of the spring type, or of the compressed gas type.

In the spring type gun, rubbers or springs are used to propel the spear from the gun, the energy being stored by forcing the spear into the gun to bias the rubber or springs. The bias is removed by some form of trigger means when it is desired to lire the spear. Of necessity, the spring means must be of considerable mass to store enough energy to propel the spear against the resistance of the water and thus this type gun is relatively heavy. The moving mass of the spring means during tiring and the sudden arrest of such motion also produce a kick in the gun which is detrimental to the accuracy of the gun.

In the compressed gas type spear gun, the spear is propelled from the gun by using a compressed gas cartridge and suddenly opening such cartridge to allow the gas contained therein to escape, the expanding gas acting directly on the butt end of the spear in the gun to force the spear through the water towards the target. Although this type gun has several advantages such as ease of use, lack of kick and lightness in weight, it has several disadvantages which are quite apparent to those using such a gun. The gas cylinders are generally usable for only one shot, and thus for prolonged underwater spear fishing a large number of such cylinders must be carried by the diver. Also, the necessity of using a fresh gas cylinder each time the gun is tired becomes an economic burden. The escaping gas issues from the gun barrel in the form of bubbles, making it difficult for the diver to see and frightening the fish in the Vicinity. Further, the gas bubbles following the spear produce cavitation, thereby decreasing the accuracy of the gun.

By utilizing the principles of the present invention, the disadvantages of the former guns enumerated above have been eliminated. The present invention contemplates an underwater spear gun having a barrel open at one end so that it may be iilled with water and so that the spear may be inserted therein. The other end of the barrel is closed and contains therein a sealed, collapsible gas reservoir. The reservoir is charged by iilling it with a gas, such as air, under pressure. In use, the spear is forced into the barrel and acts as a piston to force the Water trapped in the barrel to collapse the reservoir, thus compressing the gas therein to build up the gas pressure thereof. When it is desired to lire the gun, the spear is released by a trigger means, allowing the reservoir to expand, causing the column of trapped water to eject the spear from the barrel. As may be appreciated, no gas escapes from the gun in the firing operation, thereby eliminating the need for recharging the reservoir on each shot. Also, no gas bubbles will issue from the gun with the attendant disadvantages enumerated above. Further, the column of water following the spear eliminates the cavitation problem. Kick is largely eliminated, as the only moving element in the gun is the collapsible element of the gas reservoir which may be made of very low mass, as will be explained in the detailed description set out below.

A spear gun constructed in accordance with the preceding principles also has a distinct safety feature, as will be realized by those in organized spear fishing groups. These groups have strict rules forbidding thepresence of loaded spear guns on the beaches they are using. Since the present gun requires that the barrel be lled with water before it may be loaded, it may be seen that accidental loading While on the beach is practically eliminated.

The present spear gun also has an advantage over conventional spring loaded spear guns other than those mentioned above, in that a higher cocking ratio may be engineered into the gun, thus producing a more powerful and more compact gun. For example, a spring gun may have a spring with a nal cocked resistance of lbs. However, the uncocked resistance of the spring is zero pounds, and thus the average resistance is 50 lbs. Assuming that the spear is cocked through a distance of two feet, 100 foot pounds of energy will be stored in the spring for propulsion purposes. However, the present gun may be designed to have the same final cocked resistance of 100 pounds, but the gas reservoir may be charged initially with 50 pounds pressure. The average force exerted on the spear is thus 75 pounds. Assuming the same two foot cocking distance, it is seen that foot pounds of energy are stored for propulsion, thus achieving a higher storage of energy for the same cocking distance and final cocked resistance.

It is an object of this invention to provide an underwater spear gun having a barrel open at one end to receive a closely tting spear and having a collapsible gas reservoir in the closed end of the barrel, whereby the reservoir may be compressed by the insertion of the spear in the barrel.

It is a further object of the invention to provide an underwater spear gun of the type set forth in the rst object with means to admit liquid under pressure to the barrel after the spear is in cocked position to further compress the gas reservoir.

It is a further object of the invention to provide a spear gun as set forth in the iirst object with means to vary the extensible Volume of the gas reservoir.

It is a still further object of the invention to provide a spear gun as set forth in the first object with means to prevent the distention of the air reservoir in its tired, or uncocked, position.

It is a further object of the invention to provide a spear gun as set forth in the rst object with a pressure balanced trigger means.

Other objects and advantages will become apparent in the course of the following detailed description.

In the accompanying drawings forming a part of this specification, and in which like numerals are used to designate like parts throughout the same,

Fig. l is a side elevation, in section, of a spear gun embodying the invention, illustrating the relation of the parts in an uncocked position;

Fig. 2 is a partial view similar to Fig. l, illustrating the relation of the parts in a cocked position;

Fig. 3 is a view similar to Fig. 2, illustrating a modified embodiment of the invention; and

Fig. 4 is a View similar to Fig. 2, illustrating a further modified embodiment of the invention.

Referring to the embodiment of the invention illustrated in Figs. l and 2, the spear gun, indicated generally by reference numeral 10, has a body 11 provided with a handle or pistol grip 12 and an internal bore 13. The internal bore 13 and the elongated tubular barrel extension 14, anchored at one end to the body 11 and extending outwardly therefrom, constitute the barrel of the gun. The internal bore 13 is radially enlarged at 16 at the rear of the body 11, and is internally threaded to receive the externally threaded housing 17 of the collapsible reservoir member 18. The housing 17 may be regarded as providing a closed end for the gun barrel.

The reservoir 18 is provided with a flexible diaphragm 19 sealingly closing the open end of the housing member, the diaphragm in its unstretched state being adapted to lie against the enlarged portion 16 and shoulder 21 of the bore 13. A rigid striker plate 22, preferably made of metal, is riveted, or aixed by other conventional means, to the diaphragm 19 so as to cover and overlap the bore 13. A check valve 23 of the type used on pneumatic tires provides means whereby the reservoir 18 may be filled with a compressible gas. As the reservoir is so charged, the diaphragm 19 will ex away from the rear end 24 of the housing member 17 and will come to rest against the enlarged end 16 and shoulder 21 of the bore. The striker plate 22 prevents the diaphragm from entering into the bore 13. As may be apppreciated, the elements 16, 21 and 22 limit the movement of the diaphragm 19 away from the housing end 24, and thus prevent excessive distention of the diaphragm even though the diaphragm is constantly under pressure when in use.

A piston 26 is mounted in the housing member 17 for longitudinal movement therein, such movement being caused by adjustment screw 27 and knob 28. An O-ring 29 prevents any escape of gas around the side of the piston 26.

A spear 31 is used with the `gun 10 and has a shaft 32 adapted to be inserted within the barrel extension 14. An Oring 33 surrounds the shaft 32 so as to provide a sealing engagement of the shaft 32 within the barrel extension 14. The rear end of the spear 31 is provided with a circumferential groove 34 having a vertically projecting rear face 36.

The trigger means for the spear gun utilizes a pressure balancing system as will now be described. The trigger member 37 is pivoted around a pivot pin 38 mounted on the body 10. Two lateral bores 39 and 41 are provided in the body, extending from the bore 13 to the trigger compartment 42. A trigger latch member or pin 43 is disposed within the bore 39, with an O-ring 44 providing a seal between the trigger latch member 43 and the bore 39. The upper end of the latch member 43 is provided with a vertical latching face 46 adapted to engage the vertical face 36 of the spear groove 34, as illustrated in Fig. 2. The lower end of the latching member 43 is pivoted to the trigger member 37 by pivot pin 47. As the liquid in the bore 13 is under pressure when the gun is cocked, a downward force will be applied on the latch member 43 tending to release it from latching engagement with the spear. To overcome this, a balance pin 48 is provided, this pin being disposed in the lateral bore 41, with an O-ring 49 providing a seal therebetween. The lowered end of the balance pin 48 is pivoted to the trigger member at pivot pin 51. As may be seen, the distance between pivot pins 38 and 51 is greater than the distance between the pivot pins 47 and 38, and thus with an equal downward force applied to both the latch member 43 and the balance pin 48, a resultant force will be applied to the trigger member 37 tending to bias it in a clockwise direction around the pivot pin 38, thus maintaining the trigger member in cocked position. This will be true regardless of the amount of pressure in the bore 13.

If desired, a compression spring 52 may be used to bias the trigger member 37 to cocked position. A halfround cam stud 53 is mounted in the body 11 to mainto a position as shown in Fig. 2 when it is desired to load the gun or pull the trigger.

A check valve 54, also of the type used on pneumatic tires, is provided on the body 11 to allow fluid to be injected into the bore 13, for a purpose to be hereinafter described. If desired, a front sight 56 may be provided on the forward end of the barrel extension 14. The check valve 23 may be used as a back sight in cooperation with the front sight 56 to obtain an alignment of the spear gun on a target.

The manner of operation of the spear gun is as follows. The reservoir 18 is charged with a compressed gas, preferably air, through the check valve 23, to a desired pressure. The gun is then taken by the diver underwater to allow the barrel to be lled with water. The spear 31 is now inserted into the open end of the barrel extension 14, as shown in Fig. 1. The gun is cocked to ring position by manually forcing the spear through the barrel towards the rear of the gun. The O-ring 33 on the spear shaft 32 prevents the water in the barrel from leaking past the spear, and thus the spear shaft acts as a piston to force the water in the barrel towards the closed end of the barrel. This forced water will exert a pressure on the diaphragm 19, compressing the air in the reservoir and causing the diaphragm 19 to llex towards the closed end 24 of the reservoir, as shown in Fig. 2. As the shaft is pushed into the gun, the rear end of the shaft will engage the `trigger piston 43 to hold the spear in cocked position.

It may be desirable to vary the cocked pressure exerted by the compressed air in the reservoir to meet various needs of the diver. This may be done by a manual adjustment of the piston 26 in the reservoir 18. To increase the internal pressure the diver may turn the adjusting knob 28 to force the piston 26 to move to the left, causing a further compression of the entrapped air. The mechanical advantages obtained by the adjustment screw 27 enable the reservoir pressure to be increased easily. Conversely, the internal reservoir pressure may be decreased by causing the piston 26 to move to the right, allowing the enclosed air to expand while the gun is in cocked position. As may be seen, this movement of the piston 26 varies the extensible volume of the reservoir 18.

Alternatively, or in addition, the initial cocked pressure may be increased by forcing water, by means of a hand pump (not shown) into the gun bore 13 through the check valve 54, after the gun is cocked. The additional water added to the gun bore will cause the diaphragm 26 to be forced further towards the right, thereby increasing the internal pressure of the reservoir.

The gun is fired from its cocked position by pulling the trigger member 37. This releases the latching member 43 from engagement with the spear which is now free to move through the barrel of the gun under the force of the compressed air in the reservoir 18. The diaphragm 19 moves toward the spear shaft forcing the water in the barrel to eject the spear from the gun. After the gun is red, it may be reloaded simply by inserting another spear in the barrel and forcing it into the gun. As no air is lost on each shot, it is not necessary to recharge the reservoir 18 for each shot. Rather, the gun may be used for as many shots are are desired Without requiring any addition of gas into the reservoir.

It is important to note that the diaphragm 19 may be made very light in weight, for it is subjected only to compressive forces, and is not subjected at all to stretching forces. With the gun unloaded but the reservoir charged with compressed gas, the diaphragm will lie against the enlarged bore section 16, and the only stress will be a compressive force causing the diaphragm to snugly fit the bore section 16. In the cocked position the diaphragm will have ilexed towards the rear of the gun, but the pressure on both sides of the diaphragm will be equal, with the diaphragm merely acting as a separation wall tain the trigger in safety position, the stud being tgrged b etwlll lill@ liquid and the gas. The lack of stretching forces on the diaphragm greatly lengthens the life of the diaphragm. Also, at no time is there any contact of the diaphragm by the spear shaft, eliminating any possible damage to the diaphragm by the shaft.

The embodiment illustrated in Fig. 3 utilizes the same principles disclosed above, but Ifurther illustrates the manner in which the gun may be modified to obtain the same results. 'Ihe reservoir 61 comprises a housing 62 screw threaded into the body 11 as before, and a collapsible bladder 63 secured to the rear wall64 of the housing. A check valve 65 enables the bladder to be charged with a compressible gas as before.

The trigger means illustrated in this embodiment comprises a trigger member 66 pivotally mounted on the body 11 on pivot pin 67. A valve 68, adapted to seat on valve seat 69, has a valve stem 71 extending through the body to cooperate with pivot pin 72 on the trigger member 66. The valve stern 71 has a longitudinal slot 73, allowing the valve to open without moving the trigger member. The valve 68 is disposed between the bladder 63 and the vrearmost position of the spear shaft 32.

The operation of this embodiment is essentially the same as described above. As the spear is forced into the barrel the water in the barrel will be forced past the valve 68, which opens against the relatively slight bias of compression spring 74, into the reservoir housing 62 to collapse the bladder 63, thereby further compressing the gas enclosed therein. After the spear is in position the gun is again ready to lire. 'Ihe pressure exerted on the lower face of the valve 68 maintains the valve in closed position to prevent loss of pressure. If desired, additional water under pressure may be forced into the reservoir housing 62 by means of the check valve 54, to increase the cocked pressure.

Firing the gun is accomplished by pulling the trigger member 67, thereby causing the valve stern 71 to move downwardly under the influence of pivot pin 72. As the valve 68 is cracked open the escaping water forces the valve to open suddenly, allowing the water to pass freely into the gun barrel from the housing member 62 to eject the spear.

Fig. 4 illustrates a further modification of the reservoir. In this embodiment, a free piston 71 is mounted for axial movement in the reservoir housing 72, the O-ring 73 preventing fluid flow between the piston and the housing. Air is charged into the reservoir housing 72 through the check valve 74, forcing the piston 71 to the left, where it comes to rest against the stop shoulder 75 of the body 11. As the gun is loaded, the column of water in the barrel will force the piston 71 rearwardly to compress the gas enclosed in the reservoir housing 72 to build up the cocked pressure. This movement of the piston 71 in effect collapses the air enclosing reservoir. The further operation of the gun is identical to that of the embodiment shown in Figs. l and 2.

As may be appreciated the various forms of collapsing reservoirs may be used with either the trigger means shown in Figs. 1 and 2 or with the trigger means shown in Fig. 3, as the overall operation of the gun will be the same.

It is to be understood that the forms of the invention, herewith shown and described, are to be taken as preferred samples of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of the invention, or the scope of the attached claims.

Having thus described our invention, we claim:

1. An underwaterspear gun comprising a tubular barrel closed at one end and adapted to be filled with liquid, a collapsible reservoir enclosing a compressible gas carried in said barrel, a spear having a shaft closely fitting in the other end of said barrel, whereby when said spear is inserted in said barrel the shaft acts as a piston to cause the liquid in said barrel to collapse said reservoir and compress said gas enclosed therein, said shaft of said spear having a notch therein adjacent one end thereof, a first lateral bore in said barrel, a latch pin carried in said rst bore and having one end thereof adapted to engage said notch to hold said spear in inserted position in said barrel, a trigger member pivotally connected to the other end of said latch pin, a second lateral bore in said barrel spaced longitudinally thereof from said first bore, a balance pin carried in said second bore and having one end thereof pivotally connected to said trigger member and the other end exposed to the interior of said barrel, said trigger member being pivotally mounted on the exterior of said barrel with the pivotal connection of said trigger member to said barrel being between the pivotal connection of the trigger member and the latch pin and balance pin and closer to the latch pin.

2. An underwater spear gun comprising a tubular barrel having a bore therethrough, said bore being closed at one end thereof, a movable member in said bore spaced from said closed end and sealed with respect to said bore to form a compressible reservoir in said barrel, a piston in said bore disposed between said movable member and said closed end, manually operable means to move said piston towards and away from said closed end, and a spear having a shaft closely tting in the other end of said bore.

3. A device as set forth in claim 2 further including check valve means in said barrel to admit gas under pressure between said movable member and said piston.

4. A device as set forth in claim 2 wherein said movable member is a diaphragm disposed across said bore and sealed thereto.

5. A device as set forth in claim 2 further including releasable latching means engaging said shaft to hold said spear in said bore after insertion therein.

6. A device as set forth in claim 5 further including a check valve means in said barrel to admit uid under pressure between said held spear and said movable member.

References Cited in the le of this patent UNITED STATES PATENTS 1,073,455 Wissler Sept. 16, 1913 1,204,803 McCullough Nov. 14, 1916 2,546,961 Amero Apr. 3, 1951 2,723,656 Andina Nov. 15, 1955 2,725,048 Koogle Nov. 29, 1955 2,784,712 Cassidy Mar. 12, 1957 FOREIGN PATENTS 909,725 France Ian. 7, 1946 490,796 Italy Feb. 16, 1954