Electrostatically Dischargeable Primer

This invention relates to pyrotechnic devices, systems and firing circuits and more particularly, to an electrostatically dischargeable (electric) primer which may be used in substantially any cartridge. In a first preferred embodiment the electric primer is characterized by an electrically non-conductive plastic case fitted with a metal or metallized plastic or carbon-filled, electrically conductive center electrode which extends into a cavity packed with pyrotechnic powder. An electrically conductive membrane seal seals the pyrotechnic powder cavity and in a first preferred embodiment a concave tower receptacle is provided in the base of the electric primer to receive and match the curved end of an electrode tower extending from an ignition coil and having a positive electrode for engaging the center electrode in the electric primer and selectively investigating the primer and carrier cartridge with an interrogation pulse and discharging the pyrotechnic powder in the primer cavity. In a second preferred embodiment, the base of the non-conductive plastic case is substantially flat and continuous, with the electrode extending therethrough at the center thereof for receiving the positive electrode of the ignition coil. Voltage applied to the center electrode of the electric primer by the ignition coil effects a spark between the center electrode and the conductive membrane seal, thus firing the pyrotechnic powder in the electric primer and, in turn, firing the cartridge in which the electric primer is inserted.

A primary advantage of the electric primer of this invention is the facility for receiving an interrogation pulse from the connecting ignition coil through the center electrode of the electric primer to determine the nature, location and/or type of electric primer and carrying cartridge under investigation, especially under circumstances where the electric primer is to be fired by a computer which orchestrates alteration of the ignition coil. Accordingly, multiple electric primers may be mounted in a non-conductive firing plate and fired in a selected sequence, either manually or by computer operation, using the ignition coils to effect ignition of the pyrotechnic primer powder, either in the absence of or after an interrogation pulse applied to all or selected ones of the electric primers for identification and/or location purposes.

One of the problems associated with conventional pyrotechnic devices and systems and corresponding firing circuits, including percussion primers, electric squibs and like devices of various design, is that of the susceptibility of these devices to premature and undesirable firing by electromagnetic and other radiation, as well as limited shelf life, high expense, environmental disposal problems and the like. For example, conventional percussion-type primers are particularly prone to accidental discharge and have limited shelf life, thus limiting the utility of these devices. Furthermore, the popular electric bridgework apparatus is susceptible to accidental discharge by stray electromagnetic and other radiation and may be expensive to use, depending upon the application desired.

My U.S. Pat. No. 5,235,127, dated Aug. 10, 1993, details a "Weapon Discharge Simulation System and Electrostatically Discharged Pyrotechnic Cartridge For Use in Said System". The device is designed to simulate the firing of weapons by igniting various signature cartridges, both singularly and in multiple burst sequences. An electronic timing source provides the necessary control and impulse to effect the ignition and a unique cartridge design provides safe and reliable performance in the system.

Accordingly, it is an object of this invention to provide a new and improved electrostatically dischargeable primer which is characterized by an electrically non-conductive, preferably plastic case, a metal or metallized plastic or carbon-filled, electrically conductive center electrode extending through the non-conductive case and base, a pyrotechnic powder cavity shaped in the plastic case for receiving a charge of powder and an electrically conductive membrane seal closing the powder cavity at the opposite end of the plastic case from the base. The base is optionally fitted with a concave tower receptacle for receiving the projecting end of an electrode tower of an ignition coil for selectively firing the primer.

Another object of this invention is to provide a new and improved electrostatically dischargeable primer which includes a shaped, electrically non-conductive plastic case having a flat base, an internal powder charge and fitted with an electrically conductive center electrode extending through the base and case into the powder charge. The case is closed at the end opposite the base by an electrically conductive membrane seal and the primer is fired by a conventional ignition coil that may also be computer-operated to emit an interrogation pulse into the primer for identification and/or location purposes prior to firing of the primer.

Still another object of this invention is to provide a new and improved electrostatically dischargeable primer having a selectively-shaped, non-conductive case with a pyrotechnic powder cavity formed therein for receiving a powder charge and closed at one end by an electrically conductive membrane seal, the opposite end of the case having a flat base that accommodates an elongated conductor or center electrode extending into the powder, with a concave tower receptacle therein. The tower receptacle communicates with the conductive electrode and is shaped to receive the electrode tower and positive electrodes of an ignition coil for selective investigative and/or location pulsing and firing of the electric primer.

Another object of this invention is to provide a new and improved electrostatically dischargeable primer having a selectively-shaped, non-conductive plastic case with a pyrotechnic powder cavity formed therein for receiving a powder charge and closed at one end by an electrically conductive membrane seal, the opposite end of the case having a flat base that accommodates an elongated conductor or center electrode extending into the powder, which conductor electrode is oriented to contact the electrode tower and positive electrode of an ignition coil for selective investigative pulsing and/or location and firing of the primer.

These and other objects of the invention are provided in a new and improved electrostatically dischargeable primer for mounting in a cartridge of choice, which electric primer includes a selectively-shaped, electrically non-conductive plastic case, an elongated metal or metallized plastic or carbon-filled center electrode extending through the plastic case from the face or base of the case, which base may be optionally provided with a concave tower receptacle for receiving the electrode tower and positive electrode of an ignition coil. The opposite end of the plastic case is closed by a metallized plastic, carbon-filled or metal conductive membrane seal spaced from the center electrode to facilitate generation of a spark in a powder cavity provided with a powder charge between the center electrode and the conductive membrane seal upon activation of the ignition coil. The electric primer may be mounted in the cartridge in conventional manner and may optionally include the capability of receiving an interrogation pulse from the ignition coil to the electric primer for identification and/or location purposes prior to firing of the electric primer and cartridge of predetermined capability, to simulate the firing of various weapons systems.

The invention will be better understood by reference to the accompanying drawing, wherein:

FIG. 1 is a side sectional view of a first preferred embodiment of the electrostatically dischargeable primer of this invention;

FIG. 2 is a base end view of the electric primer illustrated in FIG. 1;

FIG. 3 is a side sectional view of an alternative preferred embodiment of the electrostatically dischargeable primer;

FIG. 4 is a base end view of the electric primer illustrated in FIG. 3;

FIG. 5 is a side sectional view of the electrostatically dischargeable primer illustrated in FIG. 1 mounted in a cartridge, seated against a firing plate and fitted with an ignition coil for interrogating and firing the electric primer and the cartridge; and

FIG. 6 is a perspective view of a typical non-conductive firing plate fitted with multiple openings for receiving multiple ignition coils and mounting corresponding electric primers and cartridges in order to simulate the firing of multiple cartridges in a selected sequence.

Referring initially to FIGS. 1 and 2 of the drawing, in a preferred embodiment the electrostatically dischargeable primer (electric primer) of this invention is identified by reference numeral 4. In a first preferred embodiment the electric primer 4 includes an electrically non-conductive electrode case 3a, which receives a metal or metallized plastic or carbon-filled, electrically conductive center electrode 3b that extends to a concave tower receptacle 11, formed in the base 3c. The tower receptacle 11 is designed to receive the curved end of the electrode tower 8 of an ignition coil 1 when the electric primer 4 is mounted in functional configuration on a non-conductive plastic firing plate 2, as illustrated in FIG. 5. The electrode tower 8 is fitted with a positive electrode 3 which seats against the center electrode 3b provided in the electric primer 4 and the opposite end of the center electrode 3b projects into a pyrotechnic or powder composition 6, packed into a powder cavity 5 shaped in the electrode case 3a. The powder 6 and powder cavity 5 are sealed at the end opposite the base 3c by means of an electrically conductive membrane seal 7, which is welded, glued or otherwise attached to the electrode case 3a and is spaced from the center electrode 3b by a spark gap 10, as illustrated in FIGS. 1 and 3.

As illustrated in FIGS. 3 and 4 of the drawing, in a second preferred embodiment of the invention the electric primer 4 is designed similar to the electric primer 4 illustrated in FIGS. 1 and 2, except that the base 3c is flat, with the center electrode 3b protruding into a flush fit therein, wherein the tower receptacle 11 is eliminated.

Referring now to FIGS. 5 and 6 of the drawing, the electric primer 4 is pressed in conventional fashion into the primer-receiving end 4b of a cartridge 4a. The electric primer 4 is oriented such that the base 3c is fitted against the flat receiving face of the non-conductive plastic plate 2 at a threaded plate opening 2a, illustrated in FIG. 6, for receiving the threaded electrode tower 8, the curved end of which electrode tower 8 projects into the concave tower receptacle 11 in the base 3c of the electric primer 4, to contact the positive electrode 3 with the exposed end of the center electrode 3b. The electric primer 4 is thus seated in the cartridge 4a in conventional manner and the ignition coil 1 is thus positioned to effect firing of the electric primer 4 at a desired time. An interrogation pulse may be emitted by the ignition coil 1 to the electric primer 4 to identify the particular type of electric primer 4 and cartridge 4a and/or locate these elements prior to firing of the electric primer 4 and the cartridges 4a, for purposes which will be hereinafter described.

Referring again to FIGS. 5 and 6 of the drawings it will be appreciated that under ordinary circumstances, multiple units of the electric primer 4 and the cartridge 4a are installed on a common non-conductive plastic plate 2 of desired size and having desired number of plate openings 2a to simulate a weapons system of desired capability. For example, under circumstances where it is desired to simulate the firing of weapons of different types for different purposes, the system may be computer-operated in the manner detailed in my U.S. Pat. No. 5,235,127 and the computer (not illustrated) electrically connected to each of the ignition coils 1 to either fire the respective electric primers 4 and cartridges 4a or investigate the particular type and/or location of electric primer 4 and cartridge 4a which is to be fired in a selected predetermined sequence by the computer. For example, the electric primers 4 and cartridges 4a which are designed to simulate the firing of a first type of shell or projectile may be identified by initially causing the corresponding ignition coils 1 to emit an interrogation pulse and identify the location and/or type of the specific electric primers 4 and cartridges 4a associated with these projectiles or shells. The projectiles or shells may then be fired by energizing the identified electric primers 4 and cartridges 4a by operation of the ignition coils 1, either manually or by computer control. Accordingly, the facility for interrogating the respective electric primers 4 and cartridges 4a prior to firing provides an inexpensive, efficient and highly effective technique for using projectiles or shells of selected design for specific purposes in a common firing plate 2 or the equivalent, in battle.

It will be appreciated by those skilled in the art that the electrode case 3a of the electric primer 4 of this invention can be constructed of substantially any electrically non-conducting material such as plastic, including polyethylene, polypropylene, ABS and the like, in non-exclusive particular, according to the knowledge of those skilled in the art. Other electrically non-conducting materials such as fiberglass and the like may also be used. The electrode case 3a can be injection molded by suitable molding techniques also well known to those skilled in the art. Furthermore, the conducting center electrode 3b can be constructed of substantially any metallized or doped or carbon-filled plastic or metal, further according to the knowledge of those skilled in the art to facilitate application of a voltage from the ignition coil 1 to effect a spark across the spark gap 10. Similarly, the conductive membrane seal 7 may be constructed of similar metallized or doped or carbon-filled plastic or metal material to further facilitate the spark across the spark gap 10 between the projecting end of the center electrode 3b and the corresponding conductive membrane seal 7, to ignite the powder 6 inside the electrode case 3a. This ignition further ignites the powder (not illustrated) in the cartridge 4a to effect simulated firing of the desired weapons system. The metallized or carbon-filled plastic components may include various types of plastic such as those innumerated above, impregnated, doped or filled with various conductive metals such as steel, aluminum, copper, carbon and the like, in non-exclusive particular, as well as metal tape applied to the plastic and further including metallized acetate, carbon and other conducting materials for the construction of the center electrode 3b and the conductive membrane seal 7 in order to effect the desired spark between these two elements. Alternatively, the center electrode 3b and the conductive membrane seal 7 or either of them may be constructed of a conductive metal such as copper, silver, aluminum or the like, for the desired purpose.

While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications may be made in the invention and the appended claims are intended to cover all such modifications which may fall within the scope and spirit of the invention.