Ammunition and explosives – Igniting devices and systems – Ignition or detonation circuit
Reexamination Certificate
1999-09-14
2001-08-14
Jordan, Charles T. (Department: 3641)
Ammunition and explosives
Igniting devices and systems
Ignition or detonation circuit
C102S207000, C102S487000, C102S489000, C102S497000
Reexamination Certificate
active
06272995
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to munitions, and more particularly to a high precision fuze mechanism for electronically generating a firing signal to detonate a hand grenade through the use of a magnetic signal generator incorporated in the fuze mechanism.
2. Discussion
Present day hand grenades typically incorporate pyrotechnic fuze mechanisms. These fuze mechanisms employ a fuze element that begins burning when the safety pin of the grenade is pulled from the grenade. At the end of a delay period the burning fuze element ignites a pyrotechnic element which in turn detonates the primary explosive compound of the grenade.
Such present day fuze mechanisms for grenades suffer from a number of drawbacks. For one, the delay time before detonation cannot be controlled with excellent accuracy and repeatability. Delay times typically fluctuate +/− about one to two seconds. Another drawback is that the performance of the fuze element degrades over time. This can cause further variations in the accuracy of the delay time implemented before the grenade is detonated.
It would therefore be advantageous to provide an electronically controlled fuze mechanism which would provide much greater accuracy and reliability in implementing the time delay before detonating the grenade. The difficulty with this has been the lack of electrical power available for powering a suitable electronic control circuit. With other forms of munitions that are launched from sea or air, often environmental elements such as wind are used to assist in generating electrical power for the various electronic components of the fuze mechanism of the munition. With a hand grenade, however, such environmental elements as wind force are not present in sufficient degree to reliably assist in providing power for a manually thrown hand grenade.
It would therefore be advantageous to provide a high precision fuze mechanism for a munition, such as a hand grenade, which incorporates a reliable, relatively low cost means for generating electrical power for a brief period of time, to thereby enable an electronic control system to be employed to control more precisely the time delay period prior to detonating the grenade.
It would also be advantageous to provide a fuze mechanism for a hand grenade which incorporates an electronic control circuit capable of implementing one or more time delay periods, through the use of small, lightweight electronic components, before the control circuit causes detonation of the grenade.
Still further, it would be advantageous to provide a high precision fuze mechanism for a hand grenade which incorporates an electrical impulse generator, which is only activated upon removal of a safety pin of the grenade and releasing of the grenade, and which generates sufficient electrical power to power an electronic control circuit for a short period of time, which may then be used to detonate the grenade.
Still further, it would be advantageous to provide a high precision fuze mechanism for a hand grenade which includes an electrical power generator and an electronic control circuit for implementing a precisely controlled time delay before causing detonation of the grenade, and which does not significantly increase the size, weight or overall cost of the hand grenade.
Furthermore, it would be advantageous to provide a high precision fuze mechanism for a hand grenade which includes an electrical power generator for powering an electronic control circuit, where the power generator is activated as soon as a safety pin of the grenade is withdrawn and the grenade is released, and which is not affected by the velocity with which the grenade is thrown or the orientation of the grenade through its trajectory or the position in which it lands, or by other environmental elements, before it is detonated.
SUMMARY OF THE INVENTION
The present invention relates to a high precision electromechanical fuze apparatus and method for arming and detonating a munition such as a grenade. In a preferred embodiment the fuze mechanism of the present invention comprises a magnetic signal generator which is electrically coupled to an electronic control system. The magnetic signal generator is comprised of an armature, a permanent magnet, a coil circumscribing the permanent magnet and an assembly for transmitting the electric current induced in the coil to the electronic control system. The armature is assembled in a “preloaded” state and held immovably by a safety pin. Removal of the safety pin allows the armature to rotate rapidly, thus causing an electric current to be induced in the coil of the magnetic signal generator. This signal is transmitted to the electronic control circuit which includes means for implementing at least one time delay before generating an electrical firing signal. The electrical firing signal is then used to activate an electric detonator which in turn causes detonation of a stab detonator. Detonation of the stab detonator causes detonation of the primary explosive charge of the munition.
In a preferred embodiment the armature is preloaded in the unarmed state by a coil spring. The entire assembly of the armature, a permanent magnet and the means for transmitting the electrical pulse signal are all housed within a magnetic impulse generator (MIG) housing. The armature includes a shaft to which is secured a rotor. The rotor carries the stab detonator. The coil spring is coupled to the shaft of the armature and the stored energy of the spring maintains the armature in the preloaded condition when a safety pin is inserted in an interfering relationship with a portion of the armature. Preferably a lever associated with the safety pin is employed, which must be released by the user before the safety pin can be removed. The lever is preferably spring loaded such that it automatically withdraws the safety pin as soon as the grenade is released by the user.
When the lever pin is released, thus causing the safety pin to be withdrawn, the energy stored in the spring is immediately dissipated, which causes the armature to be rotated rapidly for several revolutions. This rapid rotational movement causes a current to be electromagnetically induced in the coil. The current is transmitted through a current transmitting assembly to an electronic control system. The electronic control system incorporates at least one timer, and preferably a pair of timers, which are each initiated upon receipt of the electrical signal from the coil. After at least one, and preferably a pair, of predetermined time delays have expired, the control circuit generates an electrical firing signal which is used to detonate an electrical detonator. The stab detonator is also moved into position adjacent the electrical detonator as soon as rotation of the armature starts to occur after the safety pin is withdrawn. Detonation of the electrical detonator causes essentially simultaneous detonation of the stab detonator, which in turn causes detonation of a booster pellet disposed adjacent the primary explosive charge of the munition, and which causes detonation of the primary explosive charge.
In a preferred embodiment, the electronic control circuit includes a first timer which is initiated upon an electrical signal being received from the coil. When this timer times out, a first switch is turned on. A second timer is also initiated when the electrical signal from the coil is received. The second timer has a second time delay which is longer than the delay period of the first timer. When the second timer times out, it turns on a second switch. Only when the first and second switches are both closed does the electronic control circuit generate an electrical firing pulse to the electrical detonator to initiate the explosive train that detonates the munition.
The fuze mechanism of the present invention thus forms a high precision, lightweight, compact and relatively inexpensive means for arming and detonating a munition such as a hand grenade after a predetermined time has elapsed.
REFERENCES:
patent: 311270
Helton Donald Robert
Hewlett James Arthur
McGregor Patrick Dwayne
Schmidt William Marc
Waller Ezra Stearns
Harness Dickey & Pierce PLC
Jordan Charles T.
KDI Precision Products Inc.
Semunegus Lulit
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