METHOD AND APPARATUS FOR INDIRECT ELECTRICAL IGNITION OF COMBUSTIBLE POWDERS

• US 3,791,302 A
• Filed: 11/10/1972
• Issued: 02/12/1974
• Est. Priority Date: 11/10/1972
• Status: Expired due to Term

• Current Assignee: Ian C. Mcleod
• Original Assignee: Ian C. Mcleod
• Inventors: McLeod, Ian C.
• Primary Examiner(s): Feinberg, Samuel
• Assistant Examiner(s): Jordan, C. T.
• Application Number:
  US05/305,374
• Time in Patent Office: 459 Days
• Field of Search: 102/7.2A,7.2R,24HC 317/80 60/39.82N,256 431/92-95,97,98 42/84
• US Class Current: 102/201
• CPC Class Codes: F21K 5/02 ignited in a non-disrupting container, e.g. photo-flash bulb
• CPC Class Codes: F23Q 13/00 Igniters not otherwise provided for

Abstract

A method and apparatus for the ignition of combustible powders using transparently shielded sources of high intensity light pulses is described. Preferably, low actuating voltage, one shot or consumable photoflash lamps are used to generate a light pulse which is absorbed by the combustible powders and produces ignition. Particularly described is a flashbulb connected to a flashing circuit and a secondary circuit in the flashing circuit for intermittently or continuously conductively monitoring the firing status of the bulb prior to flashing. Particularly preferred combustible powders are nitrocellulose and/or black powders which because of their black color are particularly light absorptive. A photoflash igniter device for practicing the method is particularly described. The igniter and method are particularly useful for generating gas pressure waves which can be used for mass movement and/or forming.

Claims

1. The method of igniting combustible powders which comprises:

a. providing a finely divided light absorptive explodable combustible powder in spaced, transparently shielded separation from an electrically conductive means for generating a high intensity visible spectrum flash light pulse upon achieving a threshold voltage which has a duration of less than about one second;

b. providing means for holding the powder in position adjacent to the shield so as to be light absorptive; and

c. providing a voltage above the threshold, thereby exposing the combustible powder to the high intensity pulse so that the powder is ignited.

2. The method of claim 1 wherein the powder comprises black powder.

3. The method of claim 2 wherein a nitrocellulose powder is mixed with the black powder.

4. The method of claim 1 wherein the powder is provided in contact with the outside surface of a conventional photoflash bulb as the conductive means for generating the light pulse.

5. The method of claim 1 wherein the conductive means for generating the light pulse is a flash bulb and wherein the powder is sealed in contact with the outside of the surface of the bulb by a sealling means.

6. The method of claim 5 wherein a light absorbing sealing means for the powder is used.

7. The method of claim 5 wherein the powder is a mixture of black and nitrocellulose powders.

8. The article of manufacture useful as an igniter which comprises:

a. an electrically conductive transparently shielded means for generating a high intensity visible spectrum flash light pulse of less than one second duration upon achieving a threshold voltage;

b. a fully divided light absorptive explodable combustible powder adjacent the surface of the shield opposite the means for generating the light pulse so as to be light ignitable; and

c. means for holding the power in position adjacent to the shield so as to be light absorptive.

9. The article of claim 8 wherein the combustible powder is a mixture of bLack and nitrocellulose gun powders.

10. The article of claim 8 wherein the means for holding the powder is a covering over the powder and shield so that the powder is held in contact with the outside surface of the shield.

11. The article of claim 10 wherein the powder is exploded by the light and wherein the cover is elastic and is projectable outward from the shield upon detonation of the powder.

12. The article of claim 8 wherein the powder is explodable by the light pulse and wherein a solid mass is associated with the powder such that it is movable by the explosion.

13. The article of claim 8 wherein the light pulse means includes reactive chemicals requiring a low threshold voltage for generation of the light pulse.

14. The article of claim 8 wherein the light pulse means is a photoflash bulb having a threshold voltage of less than about five volts.