Electrically initiated inertial igniters for thermal batteries and the like
A method for electrically initiating an inertial igniter for a munition is provided. The method including: generating electrical power upon a firing acceleration of the munition: powering circuitry on board the munition with the generated electrical power; and electrically determining, at the circuitry, whether an acceleration profile experienced by the munition is an all-fire condition.
1. An electrically initiated inertial igniter for a munition, the electrically initiated inertial igniter comprising:
an electrical energy harvesting device for generating a voltage over a duration of an acceleration of the munition;
a first circuit powered by the electrical energy harvesting device for determining when the acceleration experienced by the munition is an all-fire condition, the first circuit having a sub circuit having at least a capacitor for directing a portion of the charge resulting from the voltage and duration to the capacitor, wherein the all-fire condition is determined based on both the voltage and duration generated by the electrical energy harvesting device and a predetermined accumulated voltage in the capacitor; and
a second circuit initiated by the first circuit when the first circuit determines that the acceleration experienced is the all-fire condition.
2. The electrically initiated inertial igniter of claim 1 , wherein the electrical energy harvesting device is a piezoelectric generator.
3. The electrically initiated inertial igniter of claim 1 , wherein the first circuit further electrically initiates pyrotechnic materials at a specified time into a flight of the munition.
4. The electrically initiated inertial igniter of claim 1 , wherein the second circuit ignites the igniter pyrotechnic materials.
5. The electrically initiated inertial igniter of claim 4 , wherein the first circuit is capable of being programmed to predetermined all-fire requirements.
6. The electrically initiated inertial igniter of claim 1 , wherein the sub circuit further includes a draining element for draining any charge accumulated in the capacitor resulting from non-firing events.
7. The electrically initiated inertial igniter of claim 6 , wherein the draining element is a resistor.
8. A method for electrically initiating an inertial igniter for a munition, the method comprising:
generating a voltage over a duration of an acceleration of the munition;
powering a capacitor in a sub circuit of a first circuit on board the munition by directing a portion of a charge resulting from the voltage and duration to the capacitor;
electrically determining, at the first circuit, whether the acceleration experienced by the munition is an all-fire condition based on both the voltage and duration of voltage generation and a predetermined accumulated voltage in the capacitor; and
initiating a second circuit by the first circuit when the first circuit determines that the acceleration experienced is the all-fire condition.
9. The method of claim 8 , wherein the generating comprises vibrating a piezoelectric generator.
10. The method of claim 8 , further comprising electrically initiating pyrotechnic materials at a specified time into a flight of the munition.
11. The method of claim 8 , further comprising programming the first circuit to predetermined all-fire requirements.
12. The method of claim 8 , further including draining any charge accumulated in the capacitor resulting from non-firing events.