Gas generator for air bag

• US 7,665,764 B2
• Filed: 01/13/2005
• Issued: 02/23/2010
• Est. Priority Date: 01/15/2004
• Status: Active Grant

• Current Assignee: Daicel Chemical Industries Limited
• Original Assignee: Daicel Chemical Industries Limited
• Inventors: Matsuda, Naoki, Hirooka, Masato
• Primary Examiner(s): Dickson; Paul N.
• Assistant Examiner(s): GOODEN JR, BARRY J
• Application Number:
  US11/033,736
• Publication Number:
  US 20050200107A1
• Time in Patent Office: 1,867 Days
• Field of Search: 280/736, 280/741, 280/742
• US Class Current: 280/741
• CPC Class Codes: B60R 2021/2633 with a plurality of inflation levels
• CPC Class Codes: B60R 2021/2648 comprising a plurality of combustion chambers or sub-chambers
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder

Abstract

The gas generator includes, a housing having a gas discharge port, a first combustion chamber defined by the housing, a first gas generating agent adapted to generate gas to inflate an air bag, the first gas generating agent having a first combustion temperature and disposed in the first combustion chamber, a second gas generating agent adapted to generate gas to inflate the air bag, the second gas generating agent having a second combustion temperature lower than the first combustion temperature and disposed in the first combustion chamber, and a first ignition unit for directly igniting at least one of the first gas generating agent and the second gas generating agent.

Claims

1. A gas generator comprising:

a housing having a gas discharge port;

an inner cylinder provided inside the housing, the inner cylinder including a partition wall dividing the inner cylinder into an upper cylinder section and a lower cylinder section;

the upper cylinder section including a partition plate dividing the upper cylinder section into an upper space at the top of the upper cylinder section above the partition plate and a lower space below the partition plate and above the partition wall;

ignition means for starting an operation of the gas generator included in the lower cylinder section;

a first gas generating agent being directly ignited by the ignition means, the first gas generating agent having a first combustion temperature and having a gas generating capacity such that when ignited the first gas generating agent will generate an amount of gas that is not less than 1.2 mol/100 g;

a second gas generating agent being ignited only by combustion of the first gas generating agent, the second gas generating agent having a second combustion temperature lower than the first combustion temperature and having a gas generating capacity such that when ignited the second gas generating agent will generate an amount of gas that substantially contributes to inflation of the air bag;

a first combustion chamber defined in the housing, the first combustion chamber accommodating, therein, only the first gas generating agent; and

a second combustion chamber defined in the housing, the second combustion chamber accommodating, therein, only the second gas generating agent, and an amount of the second gas generating agent is greater than an amount of the first gas generating agent.

2. A gas generator, comprising:

a housing;

an inner cylinder provided inside the housing, the inner cylinder including a partition wall dividing the inner cylinder into an upper cylinder section above the partition wall and a lower cylinder section below the partition wall;

the upper cylinder section including a partition plate dividing the upper cylinder section into a first space below the partition plate and above the partition wall and a second space above the partition plate, the first space including a first combustion chamber and the second space including a second combustion chamber;

the partition plate including at least one communication opening for allowing the first combustion chamber to directly communicate with the second combustion chamber, the second space further including at least one port for discharging gasses from both the first combustion chamber and the second combustion chamber to an area outside of the second space that is coupled to an air bag;

ignition means provided in the lower cylinder section below the partition wall;

a first gas generating agent disposed in the first combustion chamber and directly ignited by the ignition means to generate gas for inflating the air bag, the first gas generating agent having a first combustion temperature and having a gas generating capacity such that when ignited the first gas generating agent will generate an amount of gas that is not less than 1.2 mol/100 g; and

a second gas generating agent disposed in the second combustion chamber and adapted to generate gas for inflating the air bag, the second gas generating agent having a second combustion temperature lower than the first combustion temperature and having a gas generating capacity such that when ignited the second gas generating agent will generate an amount of gas that substantially contributes to inflation of the air bag,

wherein a total opening area of the at least one communication opening is determined based on a total surface area of the first gas generating agent.

3. The gas generator for an air bag as claimed in claim 2, wherein an interior of the first combustion chamber and an interior of the second combustion chamber have relative capacities in relation to an amount of the first gas generating agent contained in the first combustion chamber and an amount of the second gas generating agent contained in the second combustion chamber.

4. The gas generator for an air bag as claimed in claim 2,

wherein the inner cylinder provided inside the housing extends between a diffuser shell and a closure shell of the housing.

5. The gas generator for an air bag as claimed in claim 2, wherein

the first gas generating agent has a non-perforated shape and the second gas generating agent has a single-perforated cylindrical shape.

6. The gas generator as claimed in claim 2, wherein a total opening area of the at least one port is determined based on a total surface area of the second gas generating agent.

7. The gas generator for an air bag as claimed in claim 2, wherein the first gas generating agent is charged in an amount that enables the second gas generating agent to be ignited and burned by combustion of the first gas generating agent.

8. The gas generator for an air bag as claimed in claim 2 or 7, wherein the ignition means includes an electric igniter that is activated by applying an operating current in order to directly ignite the first gas generating agent.

9. The gas generator for an air bag as claimed in claim 2 or 7, wherein the first combustion temperature is between 1700 and 3000°

C., and the second combustion temperature is between 1000 and 1700°

C.

10. The gas generator for an air bag as claimed in claim 7, further comprising:

a third combustion chamber located inside the housing;

a fourth combustion chamber located inside the housing and having at least one second communication hole for allowing communication between the third combustion chamber and the fourth combustion chamber;

a third gas generating agent consisting of pellets and disposed in the third combustion chamber and adapted to generate gas to contribute to the inflation of the air bag, the third gas generating agent having a third combustion temperature;

a fourth gas generating agent disposed in the fourth combustion chamber and adapted to generate gas to contribute to the inflation of the air bag, the fourth gas generating agent having a fourth combustion temperature lower than the third combustion temperature; and

second ignition means for directly igniting the third gas generating agent, such that combustion of the fourth gas generating agent is initiated by gasses and heat generated by combustion of the third gas generating agent communicated to the fourth gas generating agent through the at least one second communication hole,

wherein the third combustion chamber accommodates only the third gas generating agent as a gas generating material.

11. The gas generator for an air bag as claimed in claim 10, wherein the third combustion temperature is between 1700 and 3000°

C., and the fourth combustion temperature is between 1000 and 1700°

C.

12. The gas generator as claimed in claim 10, wherein the third combustion chamber is formed in the lower cylinder section below the partition wall and the fourth combustion chamber is formed between a wall of the inner cylinder and the housing with the at least one second communication hole for allowing communication between the third combustion chamber and the fourth combustion chamber being formed as at least one opening in the wall of the inner cylinder.