Electrode ignition and control of electrically operated propellants

Patent metadata

Field	Value
Publication number	US-10145337-B2
Application number	US-201615197421-A
Country	US
Kind code	B2
Filing date	Jun 29, 2016
Priority date	Jun 29, 2016
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

Electrical ignition of electrically operated propellant in a gas generation system provides an ignition condition at an ignition surface between a pair of electrodes that satisfies three criteria of a current density J that exhibits a decreasing gradient along an axis normal to an ignition surface, is substantially constant across the ignition surface and exceeds an ignition threshold at the ignition surface. These criteria may be satisfied by one or more of an angled electrode configuration, a segmented electrode configuration or an additive to the electrically operated propellant that modifies its conductivity. These configurations improve burn rate control and consumption of the available propellant and are scalable to greater propellant mass to support larger gas generation systems.

First claim

We claim:

1. A gas generation system, comprising:
a combustion chamber;
an electrically operated propellant within the combustion chamber; and
a pair of electrodes configured for coupling with an electrical power source, said electrical power source configured to apply an electrical input across the electrodes creating an ignition condition in which (a) a current density (J) through the propellant between the pair of electrodes on an ignition surface exhibits a decreasing gradient along an axis normal to the ignition surface, (b) a contour of the ignition surface approximately matches a contour of current lines between the electrodes to within 5% such that current density J is approximately constant across the ignition surface to within 5% and (c) the current density J at the ignition surface exceeds an ignition threshold as approximately all of ignition surface burns and regresses along the axis.

2. The gas generation system of claim 1 , wherein at least 95% of the ignition surface burns as the surface regresses along the axis.

3. The gas generation system of claim 1 , wherein the system comprises at least 10 grams of the electrically operated propellant that is consumed as the ignition surface burns and regresses along the axis.

4. The gas generation system of claim 1 , wherein the system comprises at least 100 grams of the electrically operated propellant that is consumed as the ignition surface burns and regresses along the axis.

5. The gas generation system of claim 1 , wherein the system comprises at least 1,000 grams of the electrically operated propellant that is consumed as the ignition surface burns and regresses along the axis.

6. The gas generation system of claim 1 , wherein said pair of electrodes are angled at greater than 0 degrees and less than 90 degrees with respect to each other such that a cross-section of the propellant between the electrodes increases in area along the axis normal to the ignition surface.

7. The gas generation system of claim 1 , further comprising a conducting or non-conductive additive in the electrically operated propellant having a gradient concentration along the axis normal to the ignition surface.

8. The gas generation system of claim 1 , wherein the electrically operated propellant comprises an ionic perchlorate-based oxidizer such that the propellant has a self-sustaining threshold pressure of at least 500 psi at which the propellant once ignited by the electrical input cannot be extinguished and below which the propellant can be extinguished by interruption of the electrical input.

9. The gas generation system of claim 8 , wherein the self-sustaining threshold pressure is at least 1,000 psi.

10. The gas generation system of claim 1 , further comprising:
an airbag coupled to the combustion chamber, wherein the combustion of the electrically operated propellant generates pressured gas that is exhausted from the chamber to inflate the airbag.

11. A gas generation, comprising:
a combustion chamber;
an electrically operated propellant within the combustion chamber; and
a pair of electrodes configured for coupling with an electrical power source, said electrical power source configured to apply an electrical input across the electrodes creating an ignition condition in which (a) a current density (J) through the propellant between the pair of electrodes on an ignition surface exhibits a decreasing gradient along an axis normal to the ignition surface, (b) a contour of the ignition surface approximately matches a contour of current lines between the electrodes such that current density J is approximately constant across the ignition surface and (c) the current density J at the ignition surface exceeds an ignition threshold as approximately all of ignition surface burns and regresses along the axis, wherein each of said pair of electrodes comprises a plurality of sub-electrodes, further comprising a network of a relay and a plurality of switches that activate one pair of sub-electrodes at a time to propagate the electrical signal along the axis.

12. A gas generation system, comprising:
a cylindrical combustion chamber;
an electrically operated propellant within the combustion chamber;
an even number of four or more said electrodes spaced radially about a longitudinal axis of the cylindrical combustion chamber embedded in said electrically operated propellant for coupling with an electrical power source, said electrical power source configured to apply an electrical input across the electrodes creating an ignition condition in which (a) a current density (J) through the propellant between the pair of electrodes on an ignition surface exhibits a decreasing gradient along an axis normal to the ignition surface, (b) a contour of the ignition surface approximately matches a contour of current lines between the electrodes such that current density J is approximately constant across the ignition surface and (c) the current density J at the ignition surface exceeds an ignition threshold as approximately all of ignition surface burns and regresses along the axis, each adjacent pair of said four or more said electrodes angled at greater than 20 degrees and less than 90 degrees with respect to each other such that a cross-section of the propellant between the electrodes increases in diameter along an axis normal to an ignition surface that regresses radially along the axis away from the longitudinal axis.

13. A gas generation system, comprising:
a cylindrical combustion chamber;
an electrically operated propellant within the combustion chamber;
at least two electrodes configured for coupling with an electrical power source, wherein said at least two said electrodes extend axially about a longitudinal axis of the cylindrical combustion chamber embedded in said electrically operated propellant, said electrical power source configured to apply an electrical input across the electrodes creating an ignition condition in which (a) a current density (J) through the propellant between the pair of electrodes on an ignition surface exhibits a decreasing gradient along an axis normal to the ignition surface, (b) a contour of the ignition surface approximately matches a contour of current lines between the electrodes such that current density J is approximately constant across the ignition surface and (c) the current density J at the ignition surface exceeds an ignition threshold as approximately all of ignition surface burns and regresses along the axis; and
a conducting or non-conductive additive in the electrically operated propellant having a gradient concentration along the longitudinal axis normal to the ignition surface,
wherein said ignition surfaces ignites at an end of the cylindrical combustion chamber and regresses along the longitudinal axis.

14. A gas generation system, comprising:
a combustion chamber;
an electrically operated propellant within the combustion chamber; and
a pair of electrodes configured for coupling with an electrical power source,
wherein said pair of electrodes are angled at greater than 20 degrees and less than 90 degrees with respect to each other such that a cross-section of the propellant between the electrodes increases in diameter along an axis normal to an ignition surface,
wherein said electrical power source is configured to apply an electrical input across the electrodes creating an ignition condition in which the ignition surface ignites and regresses along the axis,
wherein the electrically operated propellant comprises an ionic perchlorate-based oxidizer such that the propellant has a self-sustaining threshold pressure of at least 500 psi at which the propellan

Assignees

• Raytheon Co

Inventors

• Summers Matt H
• Villarreal James K
• Langhenry Mark T
• Danforth Jeremy C
• Walter John W

Classifications

• F02K9/95

  characterised by starting or ignition means or arrangements (safety devices F02K9/38) · CPC title

• F42C19/0819

  Primers or igniters for the initiation of rocket motors, i.e. pyrotechnical aspects thereof · CPC title

• B60R2021/26029

  Ignitors · CPC title

• F02K9/94

  Re-ignitable or restartable rocket- engine plants; Intermittently operated rocket-engine plants · CPC title

• F02K9/26 Primary

  Burning control {(F02K9/10, F02K9/34, F02K9/86, F02K9/92 and F02K9/94 take precedence)} · CPC title