Igniter for gas bag inflator

• US 5,772,243 A
• Filed: 08/22/1997
• Issued: 06/30/1998
• Est. Priority Date: 12/04/1995
• Status: Expired due to Fees

• Current Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Original Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Inventors: Green, David J., Lauritzen, Donald R.
• Primary Examiner(s): Johnson, Brian L.
• Assistant Examiner(s): English, Peter C.
• Application Number:
  US08/916,558
• Time in Patent Office: 312 Days
• Field of Search: 280/741, 280/736, 280/737, 280/740, 280/742, 102/202.14, 102/202.5, 102/202.12, 102/530, 102/531, 422/166, 422/165, 422/164
• US Class Current: 280/741
• CPC Class Codes: B60R 2021/26029 Ignitors
• CPC Class Codes: B60R 2021/26064 characterised by auto-ignition means
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder
• CPC Class Codes: F42B 3/04 for producing gas under pressure generators of inflation fluid especially adapted for vehicle air bags B60R21/26

Abstract

A low pressure igniter system for a gas bag inflator using a head-end chamber or closure to house a pyrotechnic ignition compound that is ignited by an initiator (squib). The housing for the igniter includes a base having a skirt that extends from the periphery of the base with the base and the skirt being a single piece of material. When initiated the low pressure igniter has a large flame front producing hot gas and particles. The low pressure igniter provides a low cost alternative to current pyrotechnic igniters, and is further advantageous in that it makes practicable fabrication of inflator housings of sheet steel.

Claims

1. A low pressure igniter for a gas bag inflator having a gas generant material in the form of pellets or wafers that is characterized by providing, when functioning, a large diameter flame front producing hot gas and particles, and which is projectile free, comprising,

an igniter housing including a base having a skirt extending from the periphery of said base, said base and said skirt of said housing being a single piece of material,

an end plate perforated over substantially the whole area thereof, said perforated end plate being attached to said skirt to form a chamber within said housing,

an initiator having an initiating portion, said initiator being mounted in the base of said housing with the initiating portion thereof extending into said chamber,

an ignition compound in said chamber, and

sealing means having a predetermined low rupture pressure positioned within said chamber and sealing said perforated end plate to retain said ignition compound in said chamber until said igniter begins to function,

whereby, upon initation of said igniter, the flame front produced by said igniter does not eject the ignited flame at great force and velocity on a front of little width into the gas generant material of said inflator but instead is expelled into the gas generant material of said inflator under a force of significantly less power as a flame having a wide diameter that weaves itself into the space between the gas generant pellets or wafers and around them and smoothly ignites them without crushing them.

2. A low pressure igniter, as defined by claim 1,

wherein said perforated end plate includes multiple holes therein.

3. A low pressure igniter, as defined by claim 1,

wherein the volume of said chamber is small whereby upon initiation of said initiator the small volume allows the pressure in the chamber to build up faster by reducing the time required to fill the volume of said chamber with gas.

4. A low pressure igniter, as defined by claim 1,

wherein said sealing means comprises a film having a thickness of about one to two thousandths of an inch.

5. A low pressure igniter, as defined by claim 4,

wherein said film of said sealing means comprises a plastic film.

6. A low pressure igniter, as defined by claim 4,

wherein said film of said sealing means comprises a metallic film.

7. A low pressure igniter, as defined by claim 1,

wherein said initiator is a side firing squib.

8. A low pressure igniter, as defined by claim 1,

further including a sunken space formed in said base of said igniter adjacent said initiator and said chamber,

an auto-ignition compound in said sunken space, and

an auto-ignition closure separating said sunken space and auto-ignition compound from said ignition compound.

9. A low pressure igniter, as defined by claim 8,

wherein said sunken space in said base has an annular shape and surrounds a portion of said initiator.

10. A low pressure igniter, as defined by claim 1,

wherein said skirt is roll crimped onto said perforated end plate to assemble said perforated end plate and said skirt together.

11. A low pressure igniter for a gas bag inflator having a gas generant material in the form of pellets or wafers that is characterized by providing, when functioning, a large diameter flame front producing hot gas and particles, and which is projectile free, comprising,

an igniter housing including a base having a skirt extending from the periphery of said base, said base and said skirt of said housing being a single piece of material,

a perforated end plate, said perforated end plate being attached to said skirt to form a chamber within said housing,

an initiator having an initiating portion, said initiator being mounted in the base of said housing with the initiating portion thereof extending into said chamber,

an ignition compound in said chamber, and

sealing means having a predetermined low rupture pressure positioned within said chamber and sealing said perforated end plate to retain said ignition compound in said chamber until said igniter begins to function,

whereby, upon initiation of said igniter, the flame front produced by said igniter does not eject the ignited flame at great force and velocity on a front of little width into the gas generant material of said inflator but instead is expelled into the gas generant material of said inflator under a force of significantly less power as a flame having a wide diameter that weaves itself into the space between the gas generant pellets or wafers and around them and smoothly ignites them without crushing them,

wherein said perforated end plate includes multiple holes therein,

wherein said skirt is roll crimped onto said perforated end plate to assemble said perforated end plate and said skirt together,

wherein said sealing means comprises a film having a thickness of about one to two thousandths of an inch, and

wherein said initiator is a side firing squib.

12. An inflator for a vehicle occupant restraint, comprising,

an elongated cylindrical housing having an elongated central passage formed therethrough,

a pyrotechnic gas generant material contained within the housing, said gas generant material being discontinuous, that is, having many openings therein and contained in said elongated central passage of said cylindrical housing,

an igniter containing substantially all of an ignition compound for igniting the pyrotechnic gas generant material and having an initiator for igniting said ignition compound, said igniter being positioned adjacent the pyrotechnic gas generant material and defining a multiple hole exit opening adjacent said central passage formed in said cylindrical housing, said multiple hole exit opening being of substantially the same diameter as that of the central passage formed in said elongated cylindrical housing,

said igniter having a housing including a base and a skirt extending from the periphery of said base and formed as a single piece of material therewith, a perforated end plate, said perforated end plate being attached to said skirt to form a chamber within said igniter housing,

said initiator being mounted in the base of said igniter housing and having an initiating portion thereof extending into said chamber, said ignition compound being contained in said chamber, and

sealing means having a predetermined low rupture pressure, sealing the perforated end plate to retain said ignition compound in said chamber until said igniter is initiated and begins to function,

whereby, when initiated, ignition and burning of the igniter ignition compound expels through said perforated end plate a large diameter low pressure flame front with lots of hot particles that is projectile free onto the gas generant material in said inflator, which flame front smoothly weaves itself into and around the openings in said discontinuous gas generant material without effecting any crushing thereof, thereby smoothly igniting said gas generant material, and

whereby, upon initiation of said igniter, the flame front produced by said igniter does not eject the ignited flame at great force and velocity on a front of little width into the gas generant material of said inflator but instead is expelled into the gas generant material of said inflator under a force of significantly less power as a flame having a wide diameter.

13. An inflator, as defined by claim 12,

wherein said generant material is comprised of a plurality of pellets.

14. An inflator, as defined by claim 12,

wherein said gas generant material is comprised of spaced wafers.

15. An inflator, as defined by claim 12,

wherein said elongated cylindrical housing is made of aluminum.

16. An inflator, as defined by claim 12,

wherein said elongated cylindrical housing is made of steel.