TIME DELAY TRIGGERING UNIT
United States Patent 3586332
A triggering unit is provided which will release at a preset time a device it is carrying such as a braking parachute. The triggering unit is housed in a missile capable of being fired through a gas or liquid medium and comprises a primary release mechanism which is connected to a slidable rod. The rod is arranged in the missile housing so that it must move against a force set up by the medium through which the missile passes or the friction forces between the rod and the housing. The rod, which is triggered by the primary release mechanism, will move a specified distance necessary to release the device carried by the unit. The time required for the shaft to move the specified distance is controlled by the forces against which the shaft must move.
US Patent References:
/1079200.html
Wilde - November 1913 - 1079200
Toy parachute
Griggs - May 1929 - 1713432
Parachute release
Hunt et al. - August 1952 - 2607159
Toy rocket and parachute
Swan - June 1956 - 2748529
Rocket and launcher therefor
Parris - December 1961 - 3014308
/1079200.html
Wilde - November 1913 - 1079200
Toy parachute
Griggs - May 1929 - 1713432
Parachute release
Hunt et al. - August 1952 - 2607159
Toy rocket and parachute
Swan - June 1956 - 2748529
Rocket and launcher therefor
Parris - December 1961 - 3014308
Application Number:
04/713465
Publication Date:
06/22/1971
Filing Date:
03/15/1968
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
446/51, 473/613, 43/6, 473/577
International Classes:
B64D17/34; F42B6/02; F42B10/50; F42B10/56; F42B12/36; B64D17/00; F42B6/00; F42B10/00; F42B12/02; F41B5/02
Field of Search:
273/106.5 43/6,86
US Patent References:
| 3452466 | INERTIA ACTUATED INFLATABLE UNDERWATER SPEAR | July 1969 | Heartness |
Primary Examiner:
Oechsle, Anton O.
Assistant Examiner:
Shapiro, Paul E.
Claims:
I claim
1. A triggering unit mounted in association with an elongated missile for slowing the travel of the missile when fired through a fluid medium which comprises:
2. The triggering unit of claim 1 wherein an elastic band is placed around the jaws to hold the jaws in a closed position.
1. A triggering unit mounted in association with an elongated missile for slowing the travel of the missile when fired through a fluid medium which comprises:
2. The triggering unit of claim 1 wherein an elastic band is placed around the jaws to hold the jaws in a closed position.
Description:
The present invention relates to an improved self-contained triggering unit which is inexpensive to manufacture, has few moving parts, is small enough to be carried in the housing of a missile and requires no remote parts for operation. The unit can release at a preset time a device such as a braking parachute to slow and stop the missile's flight, or other devices such as dye markers for indicating the location of the missile. Because the triggering unit is so compact and requires no remote parts for operation, it has particular utility in arrow shafts and watergun spears for stopping the shaft or spear after it has travelled a specified distance. The triggering unit also is useful in toy rockets and planes.
The triggering unit in accordance with the invention comprises a primary release mechanism carried by a missile and which acts upon a slidable rod. The rod, in turn, is slidably mounted in a housing. Preferably, the housing which carries the rod is the missile housing in order to reduce the overall weight of the entire unit. This is particularly important where the triggering unit is to be assembled in an arrow or spear in which case the effect of drag on the arrow or spear because of excessive weight should be avoided. The primary release mechanism, which acts upon the rod, is arranged so that once the missile is fired it will permit the rod to slide within the housing. The rate at which the rod moves is controlled by resulting the forces against which the rod must move. These forces are set up by the medium through which the missile passes or the forces caused by the friction between the rod and the housing.
A device such as a braking parachute, which is carried by the missile, and controlled by the rod will be released after the rod has moved a specified distance within the housing. Once the parachute has been released it will slow and then abort the flight of the missile. The distance that the missile travels before being slowed and stopped is controlled by regulating the speed at which the rod moves within the housing. More particularly, the average velocity of the missile multiplied by the time it takes the rod to move from its preset position to its triggering position equals the total distance the missile will travel before the parachute will act to abort the flight. Because the entire triggering unit is carried within the missile, there are none of the problems or complexities of using ground control means to trigger the unit. Up until this invention, the only devices which could be used in arrows or spears for slowing the device required the use of ground cords or devices which could only stop the arrow after it contacted foliage along the ground. The triggering unit of the present invention eliminates these drawbacks by having the missile carry the entire triggering unit which can release the parachute in midflight.
The importance of the present invention when used in an arrow or underwater spear becomes evident when it is realized that loss of most arrows in hunting or target shooting results from missing the target and falling into the surrounding foliage. With the present triggering unit, the braking device can be released after the arrow should have contacted the target. If the target is missed the braking means will be released, stopping the flight of the arrow just beyond the target for easy recovery.
Another advantage of the triggering unit is that because there are very few moving parts, there is very little chance that the unit will fail to function. In addition, since the parts of the unit are arranged at the back portion of the housing and most of the impact forces are absorbed at the front end upon contact on the target, there is very little chance of damage to the rearwardly mounted working parts of the unit.
Another important feature of the triggering unit is that it can be readily reassembled in the field after it has been used without the need for any special equipment or personnel. The reassembly procedure only requires reinserting the rod into the missile housing and resetting the primary release mechanism.
Further details of the present invention and its advantages will be readily understood by reference to the accompanying drawings which illustrate preferred embodiments of the invention and in which:
FIG. 1A and 1B are a cross-sectional view of the missile with the primary release mechanism in the unset position;
FIG. 2 is a cross-sectional view of the back portion of the missile with the primary release mechanism in the set position;
FIG. 3 is a section taken along the line 3-3 of FIG. 2;
FIG. 4 is a modified form of the primary release mechanism;
FIG. 5 shows a missile carrying the primary release mechanism of FIG. 4 with the primary release mechanism in the set position; and
FIG. 6 shows the missile of FIG. 5 after the primary release mechanism has been triggered.
Referring to FIG. 1A and 1B, for purposes of illustration the missile is shown as an arrow 10 having a shaft or stele 12, a pointed head 14 secured to the forward end of the shaft and a nock 16 secured to the back of the shaft. Fletching or feathering not shown in the drawing is usually provided near the end of the shaft 12 to stabilize the flight of the arrow 10.
The shaft 12 is a hollow tube made of a suitable structural material such as wood or metal. An opening 13 is provided in the forward end of the shaft, the importance of which will be explained herein.
Slidably seated in the shaft 12 is a primary release mechanism 18, slide means 19 having the general shape of a cylindrical rod and hereinafter referred to as a rod, and a valve block 20. The primary release mechanism 18 comprises a housing 21, a stem 22, a locking cam follower 23, a pin 24 and a spring 26. The housing 21 as can be seen from FIGS. 1A and 2 has cam surfaces 28 along its inside wall. The cam surfaces in which there are at least two, are spaced around the periphery of the housing 21 and have two extended portions 28a connected by a ledge 28b. The importance of the cam surfaces will be explained below.
The stem has a narrow portion 30 which passes through an opening 31 in the nock 16. The narrow portion has a slot 32 cut therein as can be seen in FIG. 1A. The stem also has a wider portion 34 which is hollowed out to form an opening 35. Around the periphery of the sidewalls of the wider portion 34 are teeth 36 which extend downward to form points 38 at the bottom of the wide portion. The cam follower 23 is made from a tube having a narrowed end 37 and a flanged portion having teeth 40 with cam surfaces 42 molded thereon.
The primary release mechanism 18 is assembled by inserting the cam follower 23 into the opening 35 of the stem so that the teeth 36 of the stem are in contact with the teeth 40 of the cam follower. One end of the pin 24 is then inserted into the cam follower 23 so that it rests up against the narrowed end 37 of the cam follower 23 and the spring 26 is mounted on the other end of the pin. The spring 26 is held in place by a stop 44 located on the pin and the rod 19. The stop 44 can be made in a form of a slidable collar so that the tension in spring 26 can be varied.
The rod 19 is a unitary structure slidably seated in the shaft 12 having four major portions. The first portion 46, against which spring 26 rests, and the second portion 50, having a smaller outside diameter then the first portion, are provided with a continuous bore 50 therethrough as can be seen from FIGS. 1A and 3. The bore 50 is made large enough to receive the pin 24. The housing 21 of the primary release mechanism 18 is attached to the first portion 46 of the rod 19 by screwing the portion onto the housing as illustrated in FIG. 2. However, other means known to the art can be used to attach the first portion 46 to the housing 21. The second portion 48 has a slot 52 passing completely through it, as best seen in FIG. 3. Two jaw members 54 having flanged sections 56 are dropped into the slot 52 and held in a closed position by an elastic band 58 wrapped around the exterior of the jaw members. When the jaw members 54 are in the open position, the flanged section 56 is seated in a recess 60 cut into the inner wall of the shaft 12.
The third portion 62 of the slidable rod 19 carries the braking means which for purposes of illustration is shown as a parachute 64. The parachute 64 is slidably mounted on the third portion 62 by means of a slip ring 66. The parachute is then carefully wrapped around the third portion 62 so that it can open when it is exposed to air currents.
The fourth portion 68 of rod 19 has a heavy duty spring 70 permanently mounted on its forward end as shown in FIG. 1B. The other end of the spring is permanently attached to the valve block 20.
The valve block 20 has an air passage 72 (see FIG. 1B) in which a valve pin 74 is seated. The valve pin 74, which also passes through the opening 13 of the shaft 12, acts to regulate the amount of air which can be drawn into the valve block 20 and to hold the valve block in place within the shaft. An annular member 76 is provided in order to absorb the inertia of the valve block 20 on impact of arrow 10 against a target and thereby prevent application of the inertia forces upon pin 74. This avoids any risk of shearing or other damage to pin 74. It should be understood however that the annular ring can be eliminated by using a shaft 12 which is solid at its front end. Thus the valve block 20 can rest up against the solid portion of the shaft. However, in order to facilitate manufacture it has been found that a tubular shaft is preferred with use of an annular ring to hold the valve block in place.
As brought out above, the head 14 of the arrow is fastened to the front of the shaft 12. The preferred method of attachment is to provide matching threads on the shaft and head and then screwing the head onto the shaft. However, it should be understood that other methods of attachment can be used such as using a resin or adhesive between the shaft and the head.
In assembling the triggering unit for firing, the primary release mechanism 18 and the slidable rod 19 are pushed into the shaft 12 in order to compress the spring 70. The nock 14 is then mounted on the shaft by means of an interlocking grove 77 and tongue 79 and held in place by a friction fit at 78. While the unit is held in this position, stem 22 is pushed forward which causes the spring 26 to compress and to move the pin 24 through the bore 50. As the pin 24 moves forward, it will spread the jaws 54 apart and seat the flanges 56 thereof within the recess 60 of the shaft 12. The seated jaws will support and maintain the spring 70 in its compressed state. When the stem 22 is pushed forward, the cam follower 23 will move forward beyond the cam surfaces 28. The stem 22 is then released causing the cam surfaces 42 of the cam follower 23 to engage the extended portions 28a of the cam surfaces 28. When this occurs, the cam follower 23 will rotate a small angular increment to seat the cam surfaces 42 on the ledge 28b and lock the cam follower in the forward position shown in FIG. 2. The cam follower 23, which is now locked in the forward position, will hold spring 26 in its compressed state and hold pin 24 between the jaws 54.
In firing the arrow 10, a bow string (not shown) is placed in the nock 16. When the arrow 10 is drawn, the bow string will move the stem 22 forward to engage the points 38 of the teeth 36 with the points of the teeth 40 and unseat the cam follower from the ledge 28b. When the arrow 10 is released from the bow, the spring 26 will act against the cam follower 23 causing the teeth 40 to slide off the points 38 of teeth 36 and rotate the cam follower 23 a small angular increment so that the cam surfaces 42 of the cam follower will not engage the cam surfaces 28 of the housing, allowing the cam follower to return to its original position shown in FIG. 1A. The spring 26 will also move the pin 24 rearwardly out of bore 50 of the second portion 48 of the rod 19. The elastic band 56 will cause the jaws 54 to close unseating the flanges 56 from the recess 60 in the shaft 12. When the arrow 10 is released from the bow, the spring 70 which is no longer restrained will start to move the rod 19 towards the back of the arrow 10. The rate at which the rod 19 can move is directly related to the amount of air allowed through port 72 of the valve block 20. Thus, if the valve 74 is closed so no air can pass through the port, the potential energy stored in the spring 70 will be insufficient to break the vacuum formed in the shaft 12 and thus the rod 19 cannot move. If, however, the valve 74 is completely opened, the spring 70 can expand at its normal rate since no vacuum will be formed in the shaft 12 as a result of air entering the shaft by way of the port 72. It can now be seen that the rate of movement of the rod 19 will depend on the degree the valve 74 is opened and the strength of the spring 70. The friction forces between the housing 21 and the rod 19 and the inside walls of the shaft 12 can be reduced to inconsequential by coating the inside walls of the shaft with a suitable material such as Teflon or a lightweight grease or oil. However, if the device is used in a toy where a critical release time is not necessary, the need for a valve can be eliminated by not making the shaft airtight and relying on the friction forces between the inside walls of the shaft 12 and the housing 21 and the rod 19 to slow the movement of the rod and housing out of the shaft 12.
As brought out above, after the arrow has been fired from the bow, the spring 70 will move the rod 19 and in turn the housing 21 out the back of the shaft. The nock 16, which is frictionally held to the shaft 12 at 78, will disengage from the shaft but will remain attached to the narrow portion 30 of the stem 22 by means of a spring-loaded setscrew 80 which is seated in the nock and the slot 32. After the nock 16 is unseated from the shaft 12, the primary release mechanism 18 and the rod 19 will move out of the shaft. When the third portion 62 of the rod 19 moves out of the shaft 12, the air currents will open the parachute 64 and short the flight of the arrow 10. The triggering unit will not be lost when the flight is interrupted since the spring 70 is permanently attached to the arrow shaft 12 by means of the valve block 20 and the rod 19 which in turn is attached to the primary release means 18. Of course, if the target area is hit, the rod 19 does not have opportunity to leave the shaft 12 and therefore the flight is not stopped.
The triggering unit is readily reassembled by reinserting the primary release means 18 and the rod 19 into the shaft 12 which will compress the spring 70. The stem 22 is then moved forward and released which will cause the cam follower 23 to rotate and seat the cam surfaces 42 on the ledge 28b in the manner described above. The pin 24, which will also move forward and be held in the forward position as a result of the cam surfaces 42 being seated on the ledge 28b, will compress spring 26 and open jaws 54 to seat the flanges 56 of the jaws in the recess 60 of the shaft 12 to hold the spring 70 in its compressed position as shown in FIG. 2. The triggering unit has now been set and the arrow 12 is again ready for use.
Another embodiment of applicant's invention is shown in FIGS. 4 through 6. The missile in these figures, for purposes of illustration, is a spear 90 for use underwater with a conventional spear gun (not shown). Referring to FIG. 5, the spear 90 consists of a shaft 92 having a hollowed front portion and made from a suitable material such as steel. The wall of the shaft 92 is provided with a small opening 94 (FIG. 5) and two slots 96, the lengths of which are parallel to the long axis of the shaft. A head 98 is secured to the forward end of the shaft 92. The head 92 has a neck region 100 which extends over a small portion of the shaft 92 beyond the point of attachment of the head to the shaft. When the head 98 is secured to the shaft 92, the neck region 100 does not contact the shaft but leaves an annular space 102 between the shaft and neck region.
Members 104, constituting a primary release mechanism, have the general shape of dished semicircles and are mounted on a pair of cylindrical members 106. The cylindrical members 106, which act as braking means for the spear, have curved cutaway portions 107 terminating in tapered ends 108. The tapered ends 108 have openings 110 for mounting purposes as will be explained hereinafter. The cylindrical members 106 are mounted on rod-shaped slide means 112, having an opening therein for receiving a pivot pin 114.
In assembling the device, the slide means 112 is seated in the shaft 92 and the opening for receiving the pivot pin 114 is aligned with the slots 96. The cylindrical members 106 are then placed over the shaft 92 so that the openings 110 are also aligned over the opening in the slide means 112. The pivot pin 114 is then inserted through the other openings 110, the opening in the slide means 112 and out through the other openings 110 and locked in place by wedging or equivalent means. The head 98 is then screwed to the shaft 92 by means of matching threads 115 and 116 in the head and shaft respectively (FIG. 5). It should be understood that other means of attaching the head to the shaft can be used such as the use of resins, adhesives or rivets. The cylindrical members 106 are then moved forward toward the front end of the spear into the annular space 102. The triggering unit is now set and the spear is ready for firing.
The primary release mechanism 107 operates when the spear 92 is fired from a conventional spear gun (not shown). Prior to firing, water enters the inner spaces and hollow interior of shaft 92 filling these up. As the spear proceeds through the water, after it is fired, the pressure of water against the primary release means 104 causes the slide means 112 to slide backwardly away from the front end of the spear. The rod 112 pushes against the water contained in the hollow shaft space to the rear of slide means 112 and this reverse pressure is relieved by passage of the water out through opening 94. Therefore, the rate at which the slide means 112 moves will depend on the size of the openings 94. If desired, a valve can be provided in the opening 94 to change the size of the opening and thus the rate of speed of the slide means 112. As the slide means 112 continues to move, the portion of the cylindrical members 106 seated in the annular space 102 will withdraw from this space causing the cylindrical members to separate from each other by a pivoting motion about the pivot pin 114 (FIG. 6). The curved cutaway portions 107 of the cylindrical members 106 are shaped to allow the cylindrical members to open a fully extended position shown in FIG. 6 without any interference.
Prior to withdrawal of the cylindrical members 106 from the annular space 102, the spear travels with very little interference since the primary release mechanism 104 offers only sufficient land surface to slide the slide means 112 but not to materially effect the speed of the spear. When the cylindrical members 106 open, the travel of the spear is aborted because of the large land surfaces of the cylindrical members which offer a large resistance to the water. The period of unimpeded travel of the spear, before cylindrical members 106 open, is preferably selected as the maximum approximate range to a target that is expected to be encountered, whereby the aborting of the spear travel will not occur prematurely. As previously explained, this time is controlled primarily by the size of the opening 94. If the spear travel is aborted, the triggering unit is reset by pivoting the cylindrical members 106 down on top of the shaft 92 and inserting the forward ends of the cylindrical members into the annular space 102.
In the embodiment of the invention illustrated in FIGS. 1--3, marker material such as dyes or smoke-producing chemicals may be packaged in a rupturable bag and placed adjacent the parachute 64, so that the marker material may be ejected simultaneously with the parachute to aid in locating the aborted missile.
It will be understood that it is intended to cover all changes and modifications of the preferred embodiments of the invention herein chosen for the purpose of illustration which do not constitute departures from the spirit and scope of the invention.
The triggering unit in accordance with the invention comprises a primary release mechanism carried by a missile and which acts upon a slidable rod. The rod, in turn, is slidably mounted in a housing. Preferably, the housing which carries the rod is the missile housing in order to reduce the overall weight of the entire unit. This is particularly important where the triggering unit is to be assembled in an arrow or spear in which case the effect of drag on the arrow or spear because of excessive weight should be avoided. The primary release mechanism, which acts upon the rod, is arranged so that once the missile is fired it will permit the rod to slide within the housing. The rate at which the rod moves is controlled by resulting the forces against which the rod must move. These forces are set up by the medium through which the missile passes or the forces caused by the friction between the rod and the housing.
A device such as a braking parachute, which is carried by the missile, and controlled by the rod will be released after the rod has moved a specified distance within the housing. Once the parachute has been released it will slow and then abort the flight of the missile. The distance that the missile travels before being slowed and stopped is controlled by regulating the speed at which the rod moves within the housing. More particularly, the average velocity of the missile multiplied by the time it takes the rod to move from its preset position to its triggering position equals the total distance the missile will travel before the parachute will act to abort the flight. Because the entire triggering unit is carried within the missile, there are none of the problems or complexities of using ground control means to trigger the unit. Up until this invention, the only devices which could be used in arrows or spears for slowing the device required the use of ground cords or devices which could only stop the arrow after it contacted foliage along the ground. The triggering unit of the present invention eliminates these drawbacks by having the missile carry the entire triggering unit which can release the parachute in midflight.
The importance of the present invention when used in an arrow or underwater spear becomes evident when it is realized that loss of most arrows in hunting or target shooting results from missing the target and falling into the surrounding foliage. With the present triggering unit, the braking device can be released after the arrow should have contacted the target. If the target is missed the braking means will be released, stopping the flight of the arrow just beyond the target for easy recovery.
Another advantage of the triggering unit is that because there are very few moving parts, there is very little chance that the unit will fail to function. In addition, since the parts of the unit are arranged at the back portion of the housing and most of the impact forces are absorbed at the front end upon contact on the target, there is very little chance of damage to the rearwardly mounted working parts of the unit.
Another important feature of the triggering unit is that it can be readily reassembled in the field after it has been used without the need for any special equipment or personnel. The reassembly procedure only requires reinserting the rod into the missile housing and resetting the primary release mechanism.
Further details of the present invention and its advantages will be readily understood by reference to the accompanying drawings which illustrate preferred embodiments of the invention and in which:
FIG. 1A and 1B are a cross-sectional view of the missile with the primary release mechanism in the unset position;
FIG. 2 is a cross-sectional view of the back portion of the missile with the primary release mechanism in the set position;
FIG. 3 is a section taken along the line 3-3 of FIG. 2;
FIG. 4 is a modified form of the primary release mechanism;
FIG. 5 shows a missile carrying the primary release mechanism of FIG. 4 with the primary release mechanism in the set position; and
FIG. 6 shows the missile of FIG. 5 after the primary release mechanism has been triggered.
Referring to FIG. 1A and 1B, for purposes of illustration the missile is shown as an arrow 10 having a shaft or stele 12, a pointed head 14 secured to the forward end of the shaft and a nock 16 secured to the back of the shaft. Fletching or feathering not shown in the drawing is usually provided near the end of the shaft 12 to stabilize the flight of the arrow 10.
The shaft 12 is a hollow tube made of a suitable structural material such as wood or metal. An opening 13 is provided in the forward end of the shaft, the importance of which will be explained herein.
Slidably seated in the shaft 12 is a primary release mechanism 18, slide means 19 having the general shape of a cylindrical rod and hereinafter referred to as a rod, and a valve block 20. The primary release mechanism 18 comprises a housing 21, a stem 22, a locking cam follower 23, a pin 24 and a spring 26. The housing 21 as can be seen from FIGS. 1A and 2 has cam surfaces 28 along its inside wall. The cam surfaces in which there are at least two, are spaced around the periphery of the housing 21 and have two extended portions 28a connected by a ledge 28b. The importance of the cam surfaces will be explained below.
The stem has a narrow portion 30 which passes through an opening 31 in the nock 16. The narrow portion has a slot 32 cut therein as can be seen in FIG. 1A. The stem also has a wider portion 34 which is hollowed out to form an opening 35. Around the periphery of the sidewalls of the wider portion 34 are teeth 36 which extend downward to form points 38 at the bottom of the wide portion. The cam follower 23 is made from a tube having a narrowed end 37 and a flanged portion having teeth 40 with cam surfaces 42 molded thereon.
The primary release mechanism 18 is assembled by inserting the cam follower 23 into the opening 35 of the stem so that the teeth 36 of the stem are in contact with the teeth 40 of the cam follower. One end of the pin 24 is then inserted into the cam follower 23 so that it rests up against the narrowed end 37 of the cam follower 23 and the spring 26 is mounted on the other end of the pin. The spring 26 is held in place by a stop 44 located on the pin and the rod 19. The stop 44 can be made in a form of a slidable collar so that the tension in spring 26 can be varied.
The rod 19 is a unitary structure slidably seated in the shaft 12 having four major portions. The first portion 46, against which spring 26 rests, and the second portion 50, having a smaller outside diameter then the first portion, are provided with a continuous bore 50 therethrough as can be seen from FIGS. 1A and 3. The bore 50 is made large enough to receive the pin 24. The housing 21 of the primary release mechanism 18 is attached to the first portion 46 of the rod 19 by screwing the portion onto the housing as illustrated in FIG. 2. However, other means known to the art can be used to attach the first portion 46 to the housing 21. The second portion 48 has a slot 52 passing completely through it, as best seen in FIG. 3. Two jaw members 54 having flanged sections 56 are dropped into the slot 52 and held in a closed position by an elastic band 58 wrapped around the exterior of the jaw members. When the jaw members 54 are in the open position, the flanged section 56 is seated in a recess 60 cut into the inner wall of the shaft 12.
The third portion 62 of the slidable rod 19 carries the braking means which for purposes of illustration is shown as a parachute 64. The parachute 64 is slidably mounted on the third portion 62 by means of a slip ring 66. The parachute is then carefully wrapped around the third portion 62 so that it can open when it is exposed to air currents.
The fourth portion 68 of rod 19 has a heavy duty spring 70 permanently mounted on its forward end as shown in FIG. 1B. The other end of the spring is permanently attached to the valve block 20.
The valve block 20 has an air passage 72 (see FIG. 1B) in which a valve pin 74 is seated. The valve pin 74, which also passes through the opening 13 of the shaft 12, acts to regulate the amount of air which can be drawn into the valve block 20 and to hold the valve block in place within the shaft. An annular member 76 is provided in order to absorb the inertia of the valve block 20 on impact of arrow 10 against a target and thereby prevent application of the inertia forces upon pin 74. This avoids any risk of shearing or other damage to pin 74. It should be understood however that the annular ring can be eliminated by using a shaft 12 which is solid at its front end. Thus the valve block 20 can rest up against the solid portion of the shaft. However, in order to facilitate manufacture it has been found that a tubular shaft is preferred with use of an annular ring to hold the valve block in place.
As brought out above, the head 14 of the arrow is fastened to the front of the shaft 12. The preferred method of attachment is to provide matching threads on the shaft and head and then screwing the head onto the shaft. However, it should be understood that other methods of attachment can be used such as using a resin or adhesive between the shaft and the head.
In assembling the triggering unit for firing, the primary release mechanism 18 and the slidable rod 19 are pushed into the shaft 12 in order to compress the spring 70. The nock 14 is then mounted on the shaft by means of an interlocking grove 77 and tongue 79 and held in place by a friction fit at 78. While the unit is held in this position, stem 22 is pushed forward which causes the spring 26 to compress and to move the pin 24 through the bore 50. As the pin 24 moves forward, it will spread the jaws 54 apart and seat the flanges 56 thereof within the recess 60 of the shaft 12. The seated jaws will support and maintain the spring 70 in its compressed state. When the stem 22 is pushed forward, the cam follower 23 will move forward beyond the cam surfaces 28. The stem 22 is then released causing the cam surfaces 42 of the cam follower 23 to engage the extended portions 28a of the cam surfaces 28. When this occurs, the cam follower 23 will rotate a small angular increment to seat the cam surfaces 42 on the ledge 28b and lock the cam follower in the forward position shown in FIG. 2. The cam follower 23, which is now locked in the forward position, will hold spring 26 in its compressed state and hold pin 24 between the jaws 54.
In firing the arrow 10, a bow string (not shown) is placed in the nock 16. When the arrow 10 is drawn, the bow string will move the stem 22 forward to engage the points 38 of the teeth 36 with the points of the teeth 40 and unseat the cam follower from the ledge 28b. When the arrow 10 is released from the bow, the spring 26 will act against the cam follower 23 causing the teeth 40 to slide off the points 38 of teeth 36 and rotate the cam follower 23 a small angular increment so that the cam surfaces 42 of the cam follower will not engage the cam surfaces 28 of the housing, allowing the cam follower to return to its original position shown in FIG. 1A. The spring 26 will also move the pin 24 rearwardly out of bore 50 of the second portion 48 of the rod 19. The elastic band 56 will cause the jaws 54 to close unseating the flanges 56 from the recess 60 in the shaft 12. When the arrow 10 is released from the bow, the spring 70 which is no longer restrained will start to move the rod 19 towards the back of the arrow 10. The rate at which the rod 19 can move is directly related to the amount of air allowed through port 72 of the valve block 20. Thus, if the valve 74 is closed so no air can pass through the port, the potential energy stored in the spring 70 will be insufficient to break the vacuum formed in the shaft 12 and thus the rod 19 cannot move. If, however, the valve 74 is completely opened, the spring 70 can expand at its normal rate since no vacuum will be formed in the shaft 12 as a result of air entering the shaft by way of the port 72. It can now be seen that the rate of movement of the rod 19 will depend on the degree the valve 74 is opened and the strength of the spring 70. The friction forces between the housing 21 and the rod 19 and the inside walls of the shaft 12 can be reduced to inconsequential by coating the inside walls of the shaft with a suitable material such as Teflon or a lightweight grease or oil. However, if the device is used in a toy where a critical release time is not necessary, the need for a valve can be eliminated by not making the shaft airtight and relying on the friction forces between the inside walls of the shaft 12 and the housing 21 and the rod 19 to slow the movement of the rod and housing out of the shaft 12.
As brought out above, after the arrow has been fired from the bow, the spring 70 will move the rod 19 and in turn the housing 21 out the back of the shaft. The nock 16, which is frictionally held to the shaft 12 at 78, will disengage from the shaft but will remain attached to the narrow portion 30 of the stem 22 by means of a spring-loaded setscrew 80 which is seated in the nock and the slot 32. After the nock 16 is unseated from the shaft 12, the primary release mechanism 18 and the rod 19 will move out of the shaft. When the third portion 62 of the rod 19 moves out of the shaft 12, the air currents will open the parachute 64 and short the flight of the arrow 10. The triggering unit will not be lost when the flight is interrupted since the spring 70 is permanently attached to the arrow shaft 12 by means of the valve block 20 and the rod 19 which in turn is attached to the primary release means 18. Of course, if the target area is hit, the rod 19 does not have opportunity to leave the shaft 12 and therefore the flight is not stopped.
The triggering unit is readily reassembled by reinserting the primary release means 18 and the rod 19 into the shaft 12 which will compress the spring 70. The stem 22 is then moved forward and released which will cause the cam follower 23 to rotate and seat the cam surfaces 42 on the ledge 28b in the manner described above. The pin 24, which will also move forward and be held in the forward position as a result of the cam surfaces 42 being seated on the ledge 28b, will compress spring 26 and open jaws 54 to seat the flanges 56 of the jaws in the recess 60 of the shaft 12 to hold the spring 70 in its compressed position as shown in FIG. 2. The triggering unit has now been set and the arrow 12 is again ready for use.
Another embodiment of applicant's invention is shown in FIGS. 4 through 6. The missile in these figures, for purposes of illustration, is a spear 90 for use underwater with a conventional spear gun (not shown). Referring to FIG. 5, the spear 90 consists of a shaft 92 having a hollowed front portion and made from a suitable material such as steel. The wall of the shaft 92 is provided with a small opening 94 (FIG. 5) and two slots 96, the lengths of which are parallel to the long axis of the shaft. A head 98 is secured to the forward end of the shaft 92. The head 92 has a neck region 100 which extends over a small portion of the shaft 92 beyond the point of attachment of the head to the shaft. When the head 98 is secured to the shaft 92, the neck region 100 does not contact the shaft but leaves an annular space 102 between the shaft and neck region.
Members 104, constituting a primary release mechanism, have the general shape of dished semicircles and are mounted on a pair of cylindrical members 106. The cylindrical members 106, which act as braking means for the spear, have curved cutaway portions 107 terminating in tapered ends 108. The tapered ends 108 have openings 110 for mounting purposes as will be explained hereinafter. The cylindrical members 106 are mounted on rod-shaped slide means 112, having an opening therein for receiving a pivot pin 114.
In assembling the device, the slide means 112 is seated in the shaft 92 and the opening for receiving the pivot pin 114 is aligned with the slots 96. The cylindrical members 106 are then placed over the shaft 92 so that the openings 110 are also aligned over the opening in the slide means 112. The pivot pin 114 is then inserted through the other openings 110, the opening in the slide means 112 and out through the other openings 110 and locked in place by wedging or equivalent means. The head 98 is then screwed to the shaft 92 by means of matching threads 115 and 116 in the head and shaft respectively (FIG. 5). It should be understood that other means of attaching the head to the shaft can be used such as the use of resins, adhesives or rivets. The cylindrical members 106 are then moved forward toward the front end of the spear into the annular space 102. The triggering unit is now set and the spear is ready for firing.
The primary release mechanism 107 operates when the spear 92 is fired from a conventional spear gun (not shown). Prior to firing, water enters the inner spaces and hollow interior of shaft 92 filling these up. As the spear proceeds through the water, after it is fired, the pressure of water against the primary release means 104 causes the slide means 112 to slide backwardly away from the front end of the spear. The rod 112 pushes against the water contained in the hollow shaft space to the rear of slide means 112 and this reverse pressure is relieved by passage of the water out through opening 94. Therefore, the rate at which the slide means 112 moves will depend on the size of the openings 94. If desired, a valve can be provided in the opening 94 to change the size of the opening and thus the rate of speed of the slide means 112. As the slide means 112 continues to move, the portion of the cylindrical members 106 seated in the annular space 102 will withdraw from this space causing the cylindrical members to separate from each other by a pivoting motion about the pivot pin 114 (FIG. 6). The curved cutaway portions 107 of the cylindrical members 106 are shaped to allow the cylindrical members to open a fully extended position shown in FIG. 6 without any interference.
Prior to withdrawal of the cylindrical members 106 from the annular space 102, the spear travels with very little interference since the primary release mechanism 104 offers only sufficient land surface to slide the slide means 112 but not to materially effect the speed of the spear. When the cylindrical members 106 open, the travel of the spear is aborted because of the large land surfaces of the cylindrical members which offer a large resistance to the water. The period of unimpeded travel of the spear, before cylindrical members 106 open, is preferably selected as the maximum approximate range to a target that is expected to be encountered, whereby the aborting of the spear travel will not occur prematurely. As previously explained, this time is controlled primarily by the size of the opening 94. If the spear travel is aborted, the triggering unit is reset by pivoting the cylindrical members 106 down on top of the shaft 92 and inserting the forward ends of the cylindrical members into the annular space 102.
In the embodiment of the invention illustrated in FIGS. 1--3, marker material such as dyes or smoke-producing chemicals may be packaged in a rupturable bag and placed adjacent the parachute 64, so that the marker material may be ejected simultaneously with the parachute to aid in locating the aborted missile.
It will be understood that it is intended to cover all changes and modifications of the preferred embodiments of the invention herein chosen for the purpose of illustration which do not constitute departures from the spirit and scope of the invention.