Airbag gas generator and an airbag apparatus

• US 20030137139A1
• Filed: 03/04/2003
• Published: 07/24/2003
• Est. Priority Date: 12/26/1997
• Status: Active Grant

• Current Assignee: Daicel Chemical Industries Limited (Daicel Corporation)
• Original Assignee: Daicel Chemical Industries Limited (Daicel Corporation)
• Inventors: Katsuda, Nobuyuki, Nakashima, Yoshihiro, Yamazaki, Masayuki, Iwai, Yasunori, Oda, Shingo
• Granted Patent: US 6,942,249 B2
• Time in Patent Office: Days
• US Class Current: 280/741
• CPC Class Codes: B60R 2021/26029 Ignitors
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder
• 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

Abstract

An airbag gas generator has a housing having gas discharge ports, an ignition unit provided within the housing for generating a combustion product upon activation thereof, the ignition unit including an igniter having an output pressure of 700 psi or higher at 20° C. atmosphere when said igniter is burned within a hermetically closed cylinder having a volume of 10 cc, and a seal device for closing the gas discharge ports to prevent fluid communication between an inside and outside of the housing before activation of the gas generator, the seal means being ruptured by an inner pressure increased as a result of the generation of the combustion product.

Claims

1. An airbag gas generator, comprising:

a housing having gas discharge ports;

ignition means provided within said housing for generating a combustion product upon activation thereof, said ignition means including an igniter having an output pressure of 700 psi or higher at 20°

C. atmosphere when said igniter is burned within a hermetically closed cylinder having a volume of 10 cc; and

seal means for closing the gas discharge ports to prevent fluid communication between an inside and outside of said housing before activation of said gas generator, said seal means being ruptured by an inner pressure increased as a result of the generation of the combustion product.

2. The airbag gas generator according to claim 27, wherein a tank pressure at 0.80×

T milliseconds after the initial rise in the tank pressure is higher than 0.70×

P (kPa).

3. The airbag gas generator according to claim 20, wherein the peak of the combustion internal pressure appears 12-16 milliseconds after the ignition current is applied.

4. The airbag gas generator according to claim 3, wherein the peak of the combustion internal pressure appears 13-15 milliseconds after the ignition current is applied.

5. An airbag gas generator according to claim 1, wherein a combustion chamber in which to burn the gas generating agent is provided in the housing of the gas generator, and the volume of the combustion chamber is expanded when the gas generator is activated or the gas generating agent is burned.

6. An airbag gas generator according to claim 1, wherein a combustion chamber in which to burn the gas generating agent is provided in the housing of the gas generator, a space of a predetermined volume containing no gas generating agent is formed in the combustion chamber, and a combustion volume of the gas generating agent is expanded into the space immediately after the gas generating agent is ignited.

7. An airbag gas generator according to claim 6, wherein the space is formed by dividing the combustion chamber by a partition member.

8. An airbag gas generator according to claim 1, wherein the ignition means includes a transfer charge to ignite and burn the gas generating agent and there are formed in the housing a first passage through which a combustion gas produced by the combustion of the transfer charge passes without passing through a gas generating agent accommodating portion and a second passage through which a combustion gas of the gas generating agent burned by the combustion gas of the transfer charge passes.

9. An airbag gas generator according to claim 8, wherein the first passage is a bypass to release the combustion gas of the transfer charge directly out of the housing, and the combustion gas of the transfer charge passing through the first passage is discharged out of the housing earlier than the combustion gas of the gas generating agent discharged through the second passage.

10. An airbag gas generator according to claim 1, wherein the gas produced by the operation of the ignition means is discharged directly through the filter means, and nothing except the filter means exists in a passage of the gas.

11. An airbag gas generator according to claim 1, further comprising a seal means to seal the gas generating agent from an atmosphere outside the housing, wherein a timing at which the seal means is ruptured to release the gas is within 3 milliseconds of the application of an ignition current when the atmosphere is at 20°

C.

12. The airbag gas generator according to claim 27, wherein a tank pressure 13 milliseconds after an application of ignition current to said ignition means is 11 kPa to 45 kPa.

13. An airbag gas generator according to -claim 11, wherein the ignition means includes an igniter and the igniter has an output of 700 psi or higher in a-normal temperature (20°

C.) atmosphere when the igniter is burned inside a hermetically closed cylinder with a volume of 10 cc.

14. The airbag gas generator according to claim 1, wherein the igniter has the output pressure of 1000-1800 psi.

15. The airbag gas generator according to claim 27, wherein a tank pressure 0.25×

T milliseconds after an application of ignition current to said ignition means is between 0.07×

P (kPa) and 0.25×

P (kPa).

16. An airbag gas generator according to claim 11, wherein the seal means is a seal tape to close gas discharge ports and a pressure at which the seal tape is ruptured is less than 100 kg/cm^{2 .}

17. The airbag gas generator according to claim 26, wherein the seal means ruptures at a pressure of 70-40 kg/cm².

18. The airbag gas generator according to claim 1, wherein an inner diameter of the gas discharge ports is in a range of 1.5 to 10 mm and said seal means is a seal tape including a seal layer of 20-200 um thick and a bonding layer or adhesive layer of 5-100 μ

m thick.

20. The airbag gas generator according to claim 1, wherein a peak of a combustion internal pressure generated by a first combustion gas generated due to combustion of said gas generating agent in the housing appears 10-20 milliseconds after an ignition current is applied to said ignition means.

21. The airbag gas generator according to claim 1, wherein the gas discharge ports includes at least a first gas discharge port having a first inner diameter and a second gas discharge port having a second inner diameter, smaller than the first inner diameter, a diameter ratio of the first gas discharge port to the second gas discharge port ranges from 4/1 to 1.1/1 and an opening area ratio of the first gas discharge port to the second gas discharge port ranges from 97/3 to 3/97.

22. An airbag gas generator according to claim 21, wherein the gas discharge ports includes only a plurality of first gas discharge ports and a plurality of second gas discharge ports.

24. A motor vehicle including an airbag gas generator, an airbag inflated by receiving a gas produced by the gas generator, and a module case to accommodate the airbag, all installed in a steering wheel in front of the driver seat, wherein the airbag gas generator is the one claimed in claim 1.

25. The gas generator of claim 1, wherein said seal means is ruptured within 3 milliseconds after an ignition current is applied to said ignition means at 20°

C.

26. The gas generator of claim 1, wherein said seal means is ruptured at a pressure less than 100 kg/cm².

27. The gas generator of claim 1, wherein, in a 60 liter tank combustion test, in which said gas generator is placed and activated in a 60 liter sealed tank, and said gas generator generates a maximum tank pressure of P (kPa) at T milliseconds after an initial rise in a tank pressure due to combustion of said gas generating agent, a tank pressure at 0.25×

T milliseconds after the initial rise in the tank pressure is lower than 0.25×

P (kPa).

28. The airbag gas generator of claim 1, wherein the combustion product is at least one of a second combustion gas and a heat.

29. The gas generator of claim 28, further comprising:

an ignition means accommodating chamber provided within said housing for accommodating said ignition means therein;

a combustion chamber provided within said housing for accommodating and burning said gas generating agent therein; and

a gas passage formed within said housing to direct the second combustion gas toward the gas discharge ports without passing through said combustion chamber.

30. An airbag gas generator of claim 28, further comprising:

an inner cylindrical member provided within said housing for forming an ignition means accommodating chamber therein, and defining a combustion chamber in an outer side thereof to burn said gas generating agent for generating a first combustion gas generated due to combustion of said gas generating agent,

wherein said inner cylindrical member includes communication ports through which the second combustion gas is discharged toward the gas discharge ports to rupture the seal means.

31. (amended) The airbag gas generator of claim 28, wherein said ignition means includes an igniter having an output pressure of 700 psi or higher at 20°

C. atmosphere when said igniter is burned within a hermetically closed cylinder having a volume of 10 cc,

wherein said igniter generates said at least one of the second combustion gas and the heat such that said seal tape is ruptured by the pressure increased by said at least one of the second combustion gas and the heat.

19. An airbag gas generator comprising:

a single ignition means activated by impacts; and

a gas generating agent ignited and burned by the ignition means to produce a combustion gas, the ignition means and the gas generating agent being accommodated in a housing with gas discharge ports;

wherein an operation performance of the gas generator is adjusted such that a tank pressure measured at 0.25×

T milliseconds will be 0.25×

P (kPa) or less where a desired tank maximum pressure in a tank combustion test is P (kPa) and a period of time from the start of rising of the tank pressure to the time when the maximum pressure P (kPa) is reached is T milliseconds and that the housing is formed with two or more kinds of gas discharge ports having different inner diameter and/or opening area.

23. An airbag apparatus, comprising:

an airbag gas generator, including

a housing having gas discharge ports,

 

ignition means provided within said housing for generating a combustion product upon activation thereof, said ignition means including an igniter having an output pressure of 700 psi or higher at 20°

C. atmosphere when said igniter is burned within a hermetically closed cylinder having a volume of 10 cc, and

seal means for closing the gas discharge ports to prevent fluid communication between an inside and outside of said housing before activation of said gas generator, said seal means being ruptured by an inner pressure increased as a result of the generation of the combustion product;

an impact sensor that detects impacts and activates the gas generator;

an airbag inflated by receiving the first combustion gas generated by the gas generator; and

a module case that accommodates the airbag.

32. A method of rupturing seal means for closing gas discharge ports formed in an airbag gas generator housing, in which a gas generating agent generating a combustion gas and ignition means for generating a combustion product, are provided, comprising:

generating the combustion product by activating the ignition means that includes an igniter having an output pressure of 700 psi or higher at 20°

C. atmosphere when said igniter is burned within a hermetically closed cylinder having a volume of 10 cc; and

rupturing said seal means by increasing an inner pressure within said housing by the generated combustion product.

33. (twice amended) An airbag gas generator, comprising:

a housing including a top plate provided with a first gas discharge port and a circumferential wall provided with a second gas discharge port;

ignition means provided within said housing such that said ignition means is positioned adjacent to the first gas discharge port for generating a combustion product; and

seal means for closing the first gas discharge port and the second gas discharge port to prevent fluid-communication between an inside and outside of said housing before activation of said gas generator, said seal means being ruptured by an increase in a pressure within said housing as a result of the generation of the combustion product, and

wherein the combustion product is discharged through the first gas discharge port.

34. (twice amended) An airbag apparatus, comprising:

an airbag gas generator, including,

a housing including a top plate provided with a first gas discharge port and a circumferential wall provided with a second gas discharge port,

ignition means provided within said housing such that said ignition means is positioned adjacent to the first gas discharge port for generating a combustion product,

seal means for closing the first gas discharge port and the second gas discharge port to prevent a fluid-communication between an inside and outside of said housing before activation of said gas generator, said seal means being ruptured by an increase in a pressure within said housing as a result of the generation of the combustion product;

an impact sensor that detects impacts and activates the gas generator;

an airbag inflated by receiving the combustion product and combustion gas; and

a module case that accommodates the airbag,

wherein the gas discharge port is formed at a portion of said housing adjacent said ignition means, and

wherein the combustion product is discharged through the first gas discharge port.

35. An air bag gas generator, comprising:

a housing having gas discharge ports;

ignition means provided within said housing for generating a combustion product upon activation thereof;

an ignition means accommodating chamber provided within said housing for accommodating said ignition means therein and including a port for discharging the combustion product therefrom;

a combustion chamber provided within said housing for accommodating and burning gas generating agent therein;

gas passage formed in an upper portion of said housing and separated from said combustion chamber for passing the combustion product therethrough toward the gas discharge ports; and

seal means for closing the gas discharge ports to prevent fluid communication between inside and outside of said housing before activating of said gas generator.

36. An air bag gas generator, comprising:

a housing having a gas discharge port formed in a circumferential wall thereof;

a combustion chamber provided inside said housing for accommodating gas generating agent therein;

ignition means provided inside said housing for generating a combustion product for igniting the gas generating agent;

an ignition means accommodating chamber provided inside said housing for accommodating said ignition means therein, the ignition means accommodating chamber including a port for discharging the combustion product therefrom, the port being formed in a circumferential portion of the ignition means accommodating chamber such that an axis of the gas discharge port and an axis of the port are substantially on the same plane and perpendicular to a center axis of said housing;

a retainer provided within said combustion chamber for supporting a cylindrical coolant that is provided within said housing, said retainer including a projecting portion formed therein such that the projecting portion is only in contact with the cylindrical coolant and extending into an inner side of said housing such that an inner end of the projecting portion is located above an imaginary line connecting the port and the gas discharge port; and

seal means for closing the gas discharge port to prevent fluid communication between inside and outside of said housing before activation of said gas generator, said seal means being adapted to rupture by receiving pressure of the combustion product.

37. An air bag gas generator according to claim 36, wherein an outer circumferential surface of the projecting portion is in contact with an inner surface of the cylindrical coolant.

38. An airbag gas generator, comprising:

a housing having gas discharge ports;

ignition means provided inside said housing for generating a combustion product upon activation thereof; and

seal means for closing the gas discharge ports to prevent fluid communication between an inside and outside of said housing before activation of said gas generator, said seal means being ruptured as a result of the combustion product directly reaching the seal means.