Small gas generator for gas actuator and pretensioner system

• US 8,176,851 B2
• Filed: 01/17/2007
• Issued: 05/15/2012
• Est. Priority Date: 01/18/2006
• Status: Active Grant

• Current Assignee: Nippon Kayaku Company Limited
• Original Assignee: Nippon Kayaku Company Limited
• Inventors: Kodama, Ryoi, Sato, Eishi, Yoshida, Hirokazu
• Primary Examiner(s): HAYES, BRET C
• Application Number:
  US12/160,937
• Publication Number:
  US 20100186615A1
• Time in Patent Office: 1,945 Days
• Field of Search: 102/530, 102/531, 280/741, 149/46, 149/61
• US Class Current: 102/530
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder
• CPC Class Codes: B60R 22/4628 characterised by fluid actuators, e.g. pyrotechnic gas generators actuating a cable B60R22/4619
• CPC Class Codes: C06B 45/00 Compositions or products which are defined by structure or arrangement of component of product explosive charges of particular form or shape F42B1/00, F42B3/00
• CPC Class Codes: C06D 5/06 by reaction of two or more solids
• CPC Class Codes: F42B 3/04 for producing gas under pressure generators of inflation fluid especially adapted for vehicle air bags B60R21/26
• CPC Class Codes: F42B 3/103 Mounting initiator heads in initiators; Sealing-plugs

Abstract

A gas generator including a cup filled with gas generant molded articles that generate gas by combustion, and an ignitor on which an ignition agent is disposed. Each gas generant molded article is formed of smokeless powders containing nitrocellulose as its major ingredient. Each gas generant molded article includes an explosive containing a fuel agent containing a guanidine derivative and/or a tetrazole derivative and an oxidizing agent containing a metal nitrate and/or perchlorate. Thus, it is possible to provide a gas generator by which the amount of CO gas generated in operation can be reduced and the combustion speed can easily be controlled, and to provide a pretensioner system provided with the gas generator.

Claims

1. A gas generator, having a combustion chamber for generating gas, for a gas actuator for operating a safety device, the generator comprising, in the combustion chamber:

first gas generant molded articles containing a fuel component including a guanidine derivative and/or a tetrazole derivative, and an oxidizing agent component containing a perchlorate; and

second gas generant molded articles containing smokeless powders including nitrocellulose as the major ingredient,

wherein the fuel component of the first gas generant molded articles has a composition different from the fuel component of the second gas generant molded articles, the first and second gas generant molded articles are each shaped in a granular form, a flake form, a pellet form, a tablet form, a multi-perforated cylinder form, a cylindrical form, or a single perforated cylinder form, and are mixed with each other to fill up the combustion chamber.

2. The gas generator according to claim 1, wherein the oxidizing agent component contains a metal nitrate and a perchlorate, wherein the metal nitrate is a salt of a metal selected out of alkali metals and alkali earth metals, and the perchlorate contains ammonium perchlorate or potassium perchlorate.

3. The gas generator according to claim 2, wherein the fuel component of the first gas generant molded articles contains one or more selected out of nitroguanidine, guanidine nitrate, bitetrazole, azobistetrazole, and 5-aminotetrazole, and the oxidizing agent is a mixture of ammonium perchlorate and strontium nitrate, or potassium perchlorate, and further contains a binder.

4. The gas generator according to claim 3, wherein the binder contains a mixture of hydroxypropylmethylcellulose and polyacrylamide.

5. The gas generator according to claim 4, wherein each first gas generant molded article further contains an additive, and a content of the fuel component of the first gas generate molded articles is 20 to 55% by weight;

a content of the oxidizing agent is 40 to 70% by weight;

a content of the binder is 2 to 10% by weight; and

a content of the additive is 2 to 10% by weight, which are controlled so that a total of the fuel component of the first gas generant molded articles, the oxidizing agent, the binder, and the additive is 100% by weight.

6. The gas generator according to claim 2, wherein a ratio Av/Bv between a volume Av of one first gas generant molded article and a volume Bv of one second gas generant molded article is 1.2 to 1.5.

7. The gas generator according to claim 2, wherein a ratio Aw/Bw between a whole weight Aw of the first gas generant molded articles and a whole weight Bw of the second gas generant molded articles is 0.5 to 2.0.

8. The gas generator according to claim 2, wherein a ratio (dPA/dt)/(dPB/dt) between a combustion speed dPA/dt of the first gas generant molded articles and a combustion speed dPB/dt of the second gas generant molded articles is 0.3 to 1.5.

9. The gas generator according to claim 2, wherein a ratio (dPA/dt)/(dPB/dt) between a combustion speed dPA/dt of the first gas generant molded articles and a combustion speed dPB/dt of the second gas generant molded articles is 0.5 to 1.0.

10. A pretensioner system comprising the gas generator according to claim 2.

11. The gas generator according to claim 1, wherein the fuel component of the first gas generant molded articles contains one or more selected out of nitroguanidine, guanidine nitrate, bitetrazole, azobistetrazole, and 5-aminotetrazole, and the oxidizing agent is a mixture of ammonium perchlorate and strontium nitrate, or potassium perchlorate, and further contains a binder.

12. The gas generator according to claim 11, wherein the binder contains a mixture of hydroxypropylmethylcellulose and polyacrylamide.

13. The gas generator according to claim 12, wherein each first gas generant molded article further contains an additive, and a content of the fuel component of the first gas generant molded articles is 20 to 55% by weight;

a content of the oxidizing agent is 40 to 70% by weight;

a content of the binder is 2 to 10% by weight; and

a content of the additive is 2 to 10% by weight, which are controlled so that a total of the fuel component of the first gas generant molded articles, the oxidizing agent, the binder, and the additive is 100% by weight.

14. The gas generator according to claim 1, wherein a ratio Av/Bv between a volume Av of one first gas generant molded article and a volume Bv of one second gas generant molded article is 1.2 to 1.5.

15. The gas generator according to claim 1, wherein a ratio Aw/Bw between a whole weight Aw of the first gas generant molded articles and a whole weight Bw of the second gas generant molded articles is 0.5 to 2.0.

16. The gas generator according to claim 1, wherein a ratio (dPA/dt)/(dPB/dt) between a combustion speed dPA/dt of the first gas generant molded articles and a combustion speed dPB/dt of the second gas generant molded articles is 0.3 to 1.5.

17. The gas generator according to claim 1, wherein a ratio (dPA/dt)/(dPB/dt) between a combustion speed dPA/dt of the first gas generant molded articles and a combustion speed dPB/dt of the second gas generant molded articles is 0.5 to 1.0.

18. A pretensioner system comprising the gas generator according to claim 1.

19. The gas generator according to claim 1, wherein the first gas generant molded articles contain no smokeless powders, and the second gas generant molded articles contain neither a fuel component including a guanidine derivative and/or a tetrazole derivative, nor an oxidizing agent component containing a perchlorate.

20. A gas generator for generating gas for a gas actuator for operating a safety device, the gas generator comprising:

an igniter having an ignition agent; and

a combustion chamber containing first gas generant molded articles containing a fuel component including a guanidine derivative and/or a tetrazole derivative, and an oxidizing agent component containing a perchlorate, and second gas generant molded articles containing smokeless powders including nitrocellulose as the major ingredient,

wherein the first and second gas generant molded articles in the combustion chamber are arranged to be ignited by burning of the ignition agent,

wherein the fuel component of the first gas generant molded articles has a composition different from the fuel component of the second gas generant molded articles, the first and second gas generant molded articles are each shaped in a granular form, a flake form, a pellet form, a tablet form, a multi-perforated cylinder form, a cylindrical form, or a single perforated cylinder form, and are mixed with each other to fill up the combustion chamber.

21. A pretensioner system comprising the gas generator according to claim 20.

22. The gas generator according to claim 20, wherein the first gas generant molded articles contain no smokeless powders, and the second gas generant molded articles contain neither a fuel component including a guanidine derivative and/or a tetrazole derivative, nor an oxidizing agent component containing a perchlorate.