Gas generator

• US 20080063993A1
• Filed: 08/27/2007
• Published: 03/13/2008
• Est. Priority Date: 08/28/2006
• Status: Active Grant

• Current Assignee: Daicel Chemical Industries Limited (Daicel Corporation)
• Original Assignee: Daicel Chemical Industries Limited (Daicel Corporation)
• Inventors: Katsuda, Nobuyuki, Oda, Shingo
• Granted Patent: US 7,614,875 B2
• Time in Patent Office: Days
• US Class Current: 431/253
• CPC Class Codes: B60R 2021/26011 using a filter through which the inflation gas passes
• CPC Class Codes: B60R 2021/26029 Ignitors
• CPC Class Codes: B60R 21/26 characterised by the inflation fluid source or means to control inflation fluid flow arrangement or mounting thereof to the vehicle B60R21/20; blasting cartridges for producing gas under pressure in general F42B3/04; initiators or igniters therefor F42B3/10

Abstract

A gas generator includes, a housing having a gas discharge port; at least one combustion chamber accommodating a gas generating agent therein; a cylindrical filter disposed between the gas discharge port and the combustion chamber; and at least one ignition device for igniting and combusting the gas generating agent, each device comprising an igniter assembly in which an electric igniter is enclosed and fixed by a metal member and a resin portion. The igniter assembly has, in the resin portion, a holder accommodation space disposed over an opening formed in a bottom portion of the housing, and fixed by a holder inserted from the outside into the opening. An inner wall surface of the holder accommodation space has concave and convex portions that engage convex and concave portions of the holder, so that the igniter assembly is fixed without being welded to the bottom portion of the housing.

Claims

1. A gas generator comprising:

a housing having a gas discharge port;

one or two or more combustion chambers accommodating a gas generating agent therein;

a cylindrical filter disposed between the gas discharge port and the combustion chamber; and

one or two or more ignition devices for igniting and combusting the gas generating agent, each device comprising an igniter assembly in which an electric igniter is enclosed and fixed by a metal member and a resin portion,

the igniter assembly having a holder accommodation space in the resin portion, being disposed so that the holder accommodation space is disposed over an opening formed in a bottom portion of the housing, the igniter assembly being fixed by a holder inserted from the outside into the opening; and

an inner wall surface of the holder accommodation space having a concave portion and a convex portion, the holder having a convex portion and a concave portion, and the concave and convex portion of the inner wall surface of the holder accommodation space and the convex and concave portion of the holder engaging with each other, so that the igniter assembly is fixed without welding to the bottom portion of the housing.

2. The gas generator according to claim 1, wherein

the holder has an annular substrate and hook portions provided to protrude in at least two locations on the annular substrate, the hook portions are made from an elastic material and have a plate-like shape having a concave portion and a convex portion, and distal end portions of the hook portions are provided to protrude and expand in the direction of an outer circumferential edge of the annular substrate;

the annular substrate of the holder is inserted from the outside into the opening formed in the bottom portion of the housing; and

the concave and convex portions on the inner wall surface of the holder accommodation space and the convex and concave portions of the hook portions engage with each other, and a force that acts to expand outwardly the distal end sections of the hook portions applies pressure to the inner wall surface of the holder accommodation space, whereby the igniter assembly is fixed without welding to the bottom portion of the housing.

3. The gas generator according to claim 1, wherein

the holder has a first annular substrate, a second annular substrate that is formed on the first annular substrate and has a diameter less than that of the first annular substrate, and hook portions provided to protrude in at least two locations on the second annular substrate, the hook portions are made from an elastic material and have a plate-like shape having a concave portion and a convex portion, and distal end portions of the hook portions are provided to protrude and expand outwardly in the direction of an outer circumferential edge of the second annular substrate;

a step surface between the first annular substrate and the second annular substrate abuts against an outer surface of the bottom portion of the housing, and the second annular substrate is inserted into the opening formed in the bottom portion of the housing; and

the concave and convex portions on the inner wall surface of the holder accommodation space and the convex and concave portions of the hook portions engage with each other, and a force that acts to expand outwardly the distal end sections of the hook portions applies pressure to the inner wall surface of the holder accommodation space, whereby the igniter assembly is fixed without welding to the bottom portion of the housing.

4. The gas generator according to claim 1 or 2, wherein a cup member that defines a agent accommodation chamber is provided, the cup member is disposed such that a bottom surface of the cup member abuts against a top surface of the housing, and a circumferential edge of an opening of the cup member abuts against the igniter collar.

5. A method of fixing one or two or more igniter assemblies without employing a welding method to a housing of a gas generator in which a housing is obtained by joining and integrating a closure shell having a opening for fixing the ignition device and a diffuser shell having a gas discharge port, the ignition device has an electric igniter enclosed and fixed by a metal member and a resin portion and the resin portion has a holder accommodation space, comprising steps of

disposing the igniter assembly so that the holder accommodation space is disposed over the opening of the closure shell, and

inserting a holder into the opening from the outside and fixing the igniter assembly to a bottom surface of the closure shell,

the steps causing a concave portion and a convex portion of an inner wall surface of the holder accommodation space to engage with a convex portion and a concave portion of the holder, so that the igniter assembly is fixed without welding to a bottom portion of the housing.

6. The method of fixing an igniter assembly according to claim 5, wherein

as the holder, one having an annular substrate and hook portions provided to protrude in at least two locations on the annular substrate is used, the hook portions being made from an elastic material and having a plate-like shape having a concave portion and a convex portion, and distal end portions of the hook portions being provided to protrude and expand in the direction of an outer circumferential edge of the annular substrate;

in the step of fixing the igniter assembly to the bottom surface of the closure shell, the holder is inserted so that the concave and convex portions on the inner wall surface of the holder accommodation space engage with the convex and concave portions of the hook portions, and a force that acts to expand outwardly the distal end sections of the hook portions applies pressure to the inner wall surface of the holder accommodation space, whereby the igniter assembly is fixed to a bottom surface of the closure shell.

7. The method of fixing an igniter assembly according to claim 5, wherein

as the holder, one having a first annular substrate, a second annular substrate that is formed on the first annular substrate and has a diameter less than that of the first annular substrate, and hook portions provided to protrude in at least two locations on the second annular substrate is used, the hook portions being made from an elastic material and having a plate-like shape with a concave portion and a convex portion, and distal end portions of the hook portions being protruded so as to expand in the direction of an outer circumferential edge of the second annular substrate,

in the step of fixing the igniter assembly to the bottom surface of the closure shell, the holder is inserted so that a step surface between the first annular substrate and second annular substrate abut against an outer surface of the bottom portion of the housing and the concave and convex portions on the inner wall surface of the holder accommodation space and the convex and concave portions of the hook portions are engaged with each other, and a force that acts to expand outwardly the distal end sections of the hook portions applies pressure to the inner wall surface of the holder accommodation space, whereby the igniter assembly is fixed to the bottom surface of the closure shell.

8. The method for fixing an igniter assembly according to claim 5 or 6, further including a step of,

after the step of fixing the igniter assembly to the bottom surface of the closure shell, disposing a cup member that forms an agent accommodation chamber such that the bottom surface thereof abuts against a top surface of the housing and a circumferential edge of an opening thereof abuts against the igniter collar.