AIRBAG GAS GENERATOR AND AN AIRBAG APPARATUS

• US 20020053788A1
• Filed: 12/11/1998
• Published: 05/09/2002
• Est. Priority Date: 12/26/1997
• Status: Active Grant

• Current Assignee: Daicel Chemical Industries Limited
• Original Assignee: Daicel Chemical Industries Limited
• Inventors: YAMAZAKI, MASAYUKI, IWAI, YASUNORI, ODA, SHINGO, KATSUDA, NOBUYUKI, NAKASHIMA, YOSHIHIRO
• Granted Patent: US 6,540,256 B2
• Time in Patent Office: Days
• US Class Current: 280/736
• 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 with a simple construction, which operates to apply as small an impact as possible to the passenger during the initial stage of its operation and thereafter rapidly increase the gas pressure to reliably protect the passenger.

The airbag gas generator which includes in the housing with gas discharge ports a single ignition means activated by impacts, a gas generating agent ignited and burned by the ignition means to produce a combustion gas, and a filter means to cool the combustion gas and/or arrest combustion residue. The operation performance of the gas generator is adjusted such that the tank pressure measured at 0.25×T milliseconds will be 0.25×P (kPa) or less where a desired tank maximum pressure in the 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.

Claims

1. 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 generate 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 a peak of a combustion maximum internal pressure in the gas generator housing occurs 10-20 milliseconds after the ignition current is applied.

2. An airbag gas generator according to claim 1, wherein the operation performance is further adjusted such that the tank pressure measured at 0.80×

T milliseconds will be 0.70×

P (kPa) or higher 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.

3. An airbag gas generator according to claim 1, wherein the peak of the combustion maximum internal pressure occurs 12-16 milliseconds after the ignition current is applied.

4. An airbag gas generator according to claim 1, wherein the peak of the combustion maximum internal pressure occurs 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. An airbag gas generator according to claim 11, wherein the tank pressure 13 milliseconds after the application of the ignition current 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. An airbag gas generator according to claim 11, wherein the ignition means includes an igniter and the igniter has an output of 1000-1800 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.

15. An airbag gas generator according to claim 11, wherein the tank pressure in the tank combustion test starts to rise 3 milliseconds after the application of the ignition current and the tank pressure 0.25×

T milliseconds after the current application 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/cm².

17. An airbag gas generator according to claim 16, wherein the rupture pressure is set at 70-40 kg/cm².

18. An airbag gas generator according to claim 16, wherein the inner diameter of the gas discharge ports is in a range of 1.5 to 10 mm and the seal tape comprises a seal layer 20-200 μ

m thick and a bonding layer or adhesive layer 5-100 μ

m thick.

20. An airbag gas generator according to claim 19, wherein a peak of a combustion maximum internal pressure in the housing, at the time of activation, occurs 10-20 milliseconds after an ignition current is applied.

21. An airbag gas generator according to claim 19, wherein, in the inner diameters of two kinds of nozzles next to each other among two or more kinds of the gas discharge ports formed in the housing, the diameter ratio of the larger to the smaller in diameter ranges from 4/1 to 1.1/1 and an opening area ratio of the larger to the smaller ranges from 97/3 to 3/97.

22. An airbag gas generator according to claim 21, wherein the gas discharge ports have two kinds of nozzle diameter, larger and smaller nozzle diameters.

23. An airbag apparatus comprising:

an airbag gas generator;

an impact sensor to detect impacts and activate the gas generator;

an airbag inflated by receiving a gas generated by the gas generator; and

a module case to accommodate the airbag;

wherein the airbag gas generator is the one claimed in claim 1.

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.

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.