Title:
Single pin initiator for a gas generating device
Kind Code:
A1


Abstract:
A single pin initiator including a header body forming an eyelet, a header lip surface and a connector shell. An initiator canister is connected to the header body and defines a first storage chamber, wherein a supply of initiation charge material is contained. A pin is positioned within the eyelet, with a pin head portion extending into the first storage chamber defined by the initiator canister. Electrical communication between the pin and the header body is provided by a bridgewire connected to the header body and preferably contacting a flat surface of the pin head portion. A supply of initiation pyrotechnic material is disposed on at least a portion of the bridgewire, and is in initiation communication with the supply of initiation charge material. Also disclosed is a passive restraint system assembly including the single pin initiator assembly of the present invention. The passive restraint system assembly includes a gas generant canister positioned over the initiator canister and securely connected to the header body, which defines a second storage chamber containing a supply of gas generant material.



Inventors:
Hamilton, Brian K. (Ogden, UT, US)
Application Number:
10/655244
Publication Date:
03/31/2005
Filing Date:
09/04/2003
Assignee:
HAMILTON BRIAN K.
Primary Class:
International Classes:
F42B3/10; F42B3/103; F42B3/12; F42B3/195; B60R; (IPC1-7): F42B3/10
View Patent Images:
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Primary Examiner:
CLEMENT, MICHELLE RENEE
Attorney, Agent or Firm:
PAULEY PETERSEN & ERICKSON (2800 W. HIGGINS ROAD, SUITE 365, HOFFMAN ESTATES, IL, 60195, US)
Claims:
1. A single pin initiator comprising: a header body forming an eyelet, a header lip surface and a connector shell; an initiator canister connected to said header body and defining a first storage chamber; a pin positioned within said eyelet, said pin including a head portion and a body portion with at least the head portion extending into said first storage chamber; a bridgewire forming electrical communication between said pin and said header body; and a supply of initiation pyrotechnic material disposed on at least a portion of said bridgewire.

2. The single pin initiator of claim 1 further comprising a supply of initiation charge material contained within said first storage chamber, said supply of initiation pyrotechnic material in initiation communication with said supply of initiation charge material.

3. The single pin initiator of claim 2 wherein said supply of initiation charge material comprises a slurry-loaded charge comprising zirconium and potassium perchlorate.

4. The single pin initiator of claim 3 wherein said slurry-loaded charge further comprises an acrylic emulsion.

5. The single pin initiator of claim 4 wherein said slurry-loaded charge comprises hydroxypropylcellulose.

6. The single pin initiator of claim 2 wherein said supply of initiation charge material includes at least one thermal conductivity enhancer.

7. The single pin initiator of claim 6 wherein said thermal conductivity enhancer comprises aluminum powder.

8. The single pin initiator of claim 2 wherein said initiation charge material has a density of about 50% to about 75% of theoretical density.

9. The single pin initiator of claim 2 wherein said initiation charge material is deformable with respect to said initiation pyrotechnic material.

10. The single pin initiator of claim 1 further comprising a glass seal securing at least a portion of said pin within said eyelet.

11. The single pin initiator of claim 1 wherein said supply of initiation pyrotechnic material comprises a slurry-loaded initiation pyrotechnic material.

12. The single pin initiator of claim 1 wherein said header body comprises a metal material.

13. A combination comprising: a single pin initiator of claim 1; a housing positioned about said header body; a gas generant canister welded to said header body to form a hermetic structural seal and defining a second storage chamber; and a supply of a gas generant material contained within said second storage chamber.

14. The combination of claim 13 wherein said housing comprises a nylon material.

15. A single pin initiator having a longitudinal axis comprising: a header body forming an eyelet, a header lip surface and a connector shell; an initiator canister mounted to said header body and forming a first storage chamber; a supply of slurry-loaded initiation charge material contained within said first storage chamber; a pin positioned within said eyelet along the longitudinal axis of said single pin initiator, said pin having a body portion and a head portion; an insulating seal positioned within said eyelet and securing said pin body portion within said eyelet; a bridgewire mounted to said header body forming electrical communication between said pin head portion and said header body; and a supply of slurry-loaded initiation pyrotechnic material disposed on at least a portion of said bridgewire, at least a portion of said supply of slurry-loaded initiation pyrotechnic material in initiating contact with at least a portion of said supply of slurry-loaded initiation charge material.

16. The single pin initiator of claim 15 wherein said initiator canister is welded onto said header body.

17. The single pin initiator of claim 15 wherein said seal comprises a glass material.

18. The single pin initiator of claim 15 wherein said supply of slurry-loaded initiation charge material is deformable.

19. The single pin initiator of claim 15 wherein said supply of slurry-loaded initiation charge material includes a binder material.

20. The single pin initiator of claim 19 wherein said binder material comprises an acrylic emulsion.

21. The single pin initiator of claim 20 wherein said acrylic emulsion includes hydroxypropylcellulose.

22. The single pin initiator of claim 15 wherein said supply of slurry-loaded initiation charge material includes a thermal conductivity enhancer.

23. The single pin initiator of claim 22 wherein said thermal conductivity enhancer includes aluminum.

24. The single pin initiator of claim 15 wherein said supply of slurry-loaded initiation charge material comprises zirconium and potassium perchlorate.

25. A passive restraint system assembly comprising: a single pin initiator assembly having a longitudinal axis, said single pin initiator assembly comprising: a header body forming an eyelet, a header lip surface and a connector shell; an initiator canister mounted to said header body and defining a first storage chamber; a supply of initiation charge material contained within said first storage chamber; a pin positioned within said eyelet along the longitudinal axis, said pin including a head portion and a body portion with at least said pin head portion extending into said first storage chamber; a glass seal securing said pin body portion within said eyelet; a bridgewire mounted to said header body and forming electrical communication between said pin head portion and said header body; a supply of initiation pyrotechnic material disposed at least in part on at least said bridgewire, at least a portion of said supply of initiation pyrotechnic material contacting at least a portion of said supply of initiation charge material; and a gas generant canister positioned over said initiator canister and securely connected to said header body, said gas generant canister defining a second storage chamber containing a supply of gas generant material.

Description:

BACKGROUND OF THE INVENTION

This invention relates generally to passive restraint systems and more particularly, to a single pin initiator such as for use in actuating a gas generator device employed in such passive restraint systems.

Common types or forms of passive restraint system actuators include airbag inflators and seat belt pretensioners. For example, such a pretensioner in conjunction with a seat belt which is extendable across the vehicle occupant maybe provided to move at least a portion of the seat belt relative to the occupant. For example, one modem seat belt is known as a 3-point restraint because it is secured to the vehicle at three points arranged about the vehicle occupant to provide a diagonal torso section and a horizontal lap portion to hold the vehicle occupant in the seat. The belt is customarily attached to the vehicle by a spring-loaded locking retractor tending to tighten the belt, and by a buckle for quick release of the belt. Seat belt pretensioners are typically sited at the retractor or at the buckle end of the restraining seat belt. Seat belt pretensioners are commonly designed to store energy which, when released, effects the pretensioning operation. Modem pretensioners are typically pyrotechnically operated. Pyrotechnically-operated pretensioners commonly comprise a sealed tube containing a gas generant composition which reacts rapidly to generate gas and rapidly expand to provide the energy to effect the pretensioning operation. For example, such generated gas may be used to drive a piston or the like, such as included or used in a pretensioner, in association with a seat belt or other restraint device. In view of the relatively small amount of gas generated or produced from, in or by such devices, as compared to gas generating inflators typically used in the inflation of inflatable restraint system airbag cushions, such devices are commonly referred to as “micro-gas generators.”

Micro-gas generators are generally composed of a housing which contains an initiation element, or squib, and a high output, gas generating material. Squibs used in such devices typically include a heated bridgewire or other electrothermal transducer to which has been applied a thermally sensitive, very rapid burning, initiation composition. Thus, micro-gas generators are typically very small devices which generally contain components corresponding to those contained in an airbag inflator, including an initiation element, an igniter composition and a high output, gas generating material, but without the same degree of physical separation typically present in airbag inflators.

For example, typical micro-gas generators may include an initiator device or assembly. The initiator device generally includes a housing that contains or stores a supply or charge of a pyrotechnic composition. The initiator device also includes a body such as adapted or suited for the secure positioning and placement of the initiator device in a larger assembly such as a passive restraint system assembly, for example. The initiator device further includes a metal eyelet forming a bore therethrough. A first conductive pin having an outer connection end and an opposed inner terminal end is positioned through the bore and held in place by an insulator. The initiator device also includes a second conductive pin having an outer connection end and an opposed inner terminal end. An initiator transducer, e.g., a bridgewire, couples the first and second conductive pins. The initiator transducer serves to ignite the charge when properly actuated. A cap or cup member surrounds, covers or otherwise encloses the charge contained therewithin and is suitably joined or connected to the eyelet.

Typical passive restraint squibs require multiple parts, such as an initiator header and a separate connector shell. Further, a surface of the header is typically required to be made smooth, such as by grinding, to provide a smooth surface against which the initiation charge can be pressed without breaking the bridgewire or damaging the electrical connection between the bridgewire and the initiator header. Additionally, conventional passive restraint squibs typically require a separately machined feature or component to maintain an initiator pyrotechnic material in proper position relative to the initiator header and the bridgewire.

In view of the above, there is a need and a demand for an improved initiator device for use in combination with a gas generator device of a passive restraint system. In particular, there is a need and a demand for an initiator device that combines the functions of the header of a conventional initiator with the connector shell in an easily fabricated single unit. Additionally, there is a need and a demand for an initiator design that does not require additional processing to provide a smooth header surface capable of withstanding compression forces or pressure to prevent breakage of a bridgewire or other transducer element. Further, there is a need and demand for providing a mechanism for securely positioning or locking the pyrotechnic material into the assembly without pressing into a receiving feature, i.e., a “chargeholder.”

SUMMARY OF THE INVENTION

A general object of the invention is to provide an improved passive restraint system assembly.

A general object of the invention is to provide a single pin initiator for use in a gas generator device employed in the passive restraint system assembly.

A more specific objective of the invention is to overcome one or more of the problems described above.

The general object of the invention can be attained, at least in part, through a single pin initiator including a header body forming an eyelet, a header lip surface and a connector shell. An initiator canister is connected to the header body and defines a first storage chamber. A pin is positioned within the eyelet. The pin includes a head portion and a body portion. At least the head portion of the pin extends into the first storage chamber. The initiator also includes a bridgewire which forms or provides electrical communication between the pin and the header body. A supply of initiation pyrotechnic material is disposed on at least a portion of the bridgewire. In accordance with one preferred embodiment, the single pin initiator further includes a supply of initiation charge material contained within the first storage chamber. The supply of initiation pyrotechnic material is in initiation communication with the supply of initiation charge material.

The header body of the present invention serves multiple purposes and/or functions including, but not limited to: functioning as a point of attachment with the bridgewire; forming an eyelet within which an insulating seal can be formed to secure a pin body portion within the eyelet; providing a connector shell for electrical connection to the passive restraint system assembly; and interfacing with the initiator cannister joined or welded to the header body.

The prior art generally fails to provide a single pin initiator having a header body that is easily fabricated or manufactured as a single part. Further, the prior art also generally fails to provide a mechanism for maintaining an initiation pyrotechnic material properly positioned within the initiator and in initiating contact with the bridgewire, without requiring additional machining of parts or components.

The invention further comprehends a single pin initiator having a longitudinal axis and including a header body forming an eyelet, a header lip surface and a connector shell. The initiator includes an initiator canister that is mounted to the header body and forms a first storage chamber, wherein a supply of slurry-loaded initiation charge material can be contained. The initiator also includes a pin positioned within the eyelet along the longitudinal axis of the single pin initiator. The pin includes a body portion and a head portion, with the pin body portion secured within the eyelet by an insulating seal positioned within the eyelet. A bridgewire mounted to the header body forms or provides electrical communication between the pin head portion and the header body. A supply of slurry-loaded initiation pyrotechnic material is disposed on at least a portion of the bridgewire, wherein at least a portion of the supply of slurry-loaded initiation pyrotechnic material is in initiating contact with at least a portion of the supply of slurry-loaded initiation charge material.

The invention still further comprehends a passive restraint system assembly including a single pin initiator assembly having a longitudinal axis. The single pin initiator assembly includes a header body that forms an eyelet, a header lip surface and a connector shell. An initiator canister is mounted to the header body and defines a first storage chamber, wherein a supply of initiation charge material is contained. A pin is positioned within the eyelet along the longitudinal axis, and includes a head portion and a body portion with at least the pin head portion extending into the first storage chamber. The pin body portion is secured within the eyelet by a glass seal. Electrical communication between the pin head portion and the header body is formed by a bridgewire mounted to the header body. A supply of initiation pyrotechnic material is disposed at least in part on at least the bridgewire, and at least a portion of the supply of initiation pyrotechnic material contacts at least a portion of the supply of initiation charge material. A gas generant canister is positioned over the initiator canister and securely connected to the header body. The gas generant canister defines a second storage chamber containing a supply of gas generant material.

Other objects and advantages will be apparent to those skilled in the art from the following detailed description taken in conjunction with the appended claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional, schematic drawing of a single pin initiator in accordance with one preferred embodiment of the invention.

FIG. 2 is a cross-sectional, schematic drawing of a single pin initiator in accordance with an alternate preferred embodiment of the invention.

FIG. 3 is a cross-sectional, schematic drawing of a passive restraint system assembly including the single pin initiator shown in FIG. 1 in accordance with one preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates generally to passive restraint systems and more particularly, to a single pin initiator such as for use in actuating a gas generator device employed in such a system assembly.

Referring to FIG. 1, the present invention provides a single pin initiator 10 for initiating the production or generation of a product gas. In one preferred embodiment of the invention, the single pin initiator 10 includes a header body 20, formed from sheet metal preferably using a stamping process. The header body 20 forms an eyelet 22 at a lip end portion 23 of the header body 20 and a connector shell 25 at an end portion opposing the lip end portion 23. As shown for example in FIG. 1, the lip end portion 23 forms a header lip or flat surface that extends radially about a periphery of the eyelet 22. Preferably, the header body 20 is formed of a suitable material, such as a stainless steel material. The eyelet 22 includes a necked portion of the header body 20 that forms a generally cylindrical or barrel-shaped portion of the header body 20 along a longitudinal length of the header body 20; the eyelet 22 transitions into a chamber 24 formed or defined by at least a portion of the header body 20, as shown for example in FIG. 1. An initiator canister 30 is connected to the header body 20 using a suitable mechanical connection, for example by laser welding the initiator canister 30 onto the header body 20. The initiator canister 30 forms or otherwise defines a first storage chamber 32, within which can be stored or contained a supply of initiation charge material 38. As shown, the initiator canister 30 can desirably be sized such as to contain therewithin a suitable amount of initiation charge material. The supply of initiation charge material 38 may comprise suitable charge materials such as known to those having ordinary skill in the art and guided by the teachings herein provided, with such charge materials generally being combustible or ignitable to produce an output charge.

In one embodiment of the invention, the supply of initiation charge material 38 includes zirconium and potassium perchlorate made into a slurry-loaded charge containing a strong binder material, such as an acrylic emulsion. In certain preferred embodiments of the invention, the acrylic emulsion may desirably include materials such as hydroxypropylcellulose for enhancing viscosity of the slurry-loaded charge. With the addition of a low level of hydroxypropylcellulose and additional carrier fluid, for example, the slurry-loaded charge is made less dense, such as to facilitate or increase the deformability of the slurry-loaded charge. Further, the thermal conductivity of the slurry-loaded charge may be enhanced with the addition of at least one thermal conductivity enhancer, such as aluminum powder. The thermal conductivity enhancer may desirably compensate for a reduction in conductivity such as due to an inherent lower density of the slurry-loaded charge, compared to conventional pressed materials. The thermal conductivity enhancer maintains a level of “no-fire” resistance to inadvertent firing. The term “slurry” as used herein refers to a free-flowing suspension of fine nonsoluble solid material in a viscous liquid matrix.

As shown in FIG. 1, a pin 40 is positioned within the eyelet 22 and generally extends along at least a portion of a longitudinal axis A of the single pin initiator 10. The pin 40 is made of an electrically conductive material, which is compatible with the sealing material in such properties as thermal expansion and bonding, such as CARPENTER 52 glass sealing nickel-iron alloy available from Carpenter Technology Corporation of Wyomissing, Pa. or the INCONEL corrosion resistant alloys of nickel and chromium of the Special Metal Corporation of Huntington, W.V., for example. The pin 40 is in electrical communication with a sensor controlled firing circuit (not shown) such as known in the art and such as effective to send a signal to the initiator 10 to effect the desired actuation thereof. The pin 40 includes or forms a head portion 42 that at least partially extends into the first storage chamber 32. Preferably, the pin head portion 42 forms or includes a generally flat or convex smooth surface 43. The pin also includes or forms a body portion 44 that is secured within the eyelet 22. For example, in one preferred embodiment of the invention, the pin body portion 44 is secured within the eyelet 22 by an insulating seal 48, for example a glass seal thereby forming a glass to metal seal. The pin 40 is maintained in spaced relationship with the header body 20 by the seal 48, thereby electrically insulating the pin 40 from the header body 20 while providing suitable physical containment of the pin body portion 44 within the eyelet 22. Other suitable insulating materials may be used to form the seal 48, for example ceramic or plastic composite materials, that provide proper insulating characteristics while maintaining the pin body portion 44 securely positioned within the eyelet 22. A portion of the pin body portion 44 may extend through the seal 48 and into the chamber 24 formed by at least a portion of the header body 20, as shown in FIG. 1.

The generally flat or convex pin head surface 43 provides an area for mechanical connection to or contact with a bridgewire 50. The pin head surface 43 allows for adjustment and control of a length of the bridgewire 50. As shown in FIG. 1, the bridgewire 50 is connected to the lip end portion 23 of the header body 20 using any suitable mechanical connection, such as a resistance weld. The bridgewire 50 spans or extends from the lip end portion 23 of the header body 20 and contacts the pin head portion 42 to form or provide electrical communication between the pin 40 and the header body 20. Preferably, but not necessarily, the bridgewire 50 is suitably connected to the surface 43 of the pin head portion 42, using a conventional mechanical connection, such as by a suitable resistence weld. The bridgewire 50 is in initiating contact with a supply of initiation pyrotechnic material 58. In one embodiment of the invention, the bridgewire 50 is heated by current from a firing circuit to ignite the initiation pyrotechnic material 58. As discussed above, the length of the bridgewire 50 can be controlled as a result of the short distance between the pin 40 and the header body 20, thus preventing disengagement of the bridgewire 50 from the pin 40 and/or the header body 20.

The supply of initiation pyrotechnic material 58 is deposited or disposed on, and preferably bonds to, at least a portion of the bridgewire 50. Thus, the surface 43 of the pin head portion 42 provides a retention mechanism for maintaining at least a portion of the supply of initiation pyrotechnic material 58 properly disposed or deposited onto and adhered to at least a portion of the bridgewire 50. Preferably, but not necessarily, at least a portion of the supply the initiation pyrotechnic material 58 is also at least partially disposed or deposited under the pin head portion 42, and adhered to a portion of the lip end portion 23. By adhering to the pin head portion 42, the lip end portion 23 and/or the glass to metal seal 48, the supply of initiation pyrotechnic material 58 is “locked” in proper position relative to the bridgewire 50, as shown for example in FIG. 1. Additionally, the pin 40 is maintained in proper position along the longitudinal axis A of the single pin initiator 10 and positive contact between the bridgewire 50 and the header body 20 and the bridgewire 50 and the pin 40 is maintained.

In one embodiment of the invention, the supply of initiation pyrotechnic material 58 comprises a slurry-loaded initiation pyrotechnic material. Those skilled in the art and guided by the teachings herein provided will appreciate that various slurry-loaded initiation pyrotechnic materials, such as known in the art, can desirably be used in the practice of the invention. Thus, the broader practice of the invention is not necessarily limited to specific or particular such pyrotechnic materials.

As discussed above, the initiator canister 30 is preferably securely connected to the header body 20 to maintain an initiation contact or communication between the supply of initiation pyrotechnic material 58 and the supply of initiation charge material 38. As shown in FIG. 1, at least a portion of the supply of initiation pyrotechnic material 58 can be in initiating contact with at least a portion of the supply of initiation charge material 38. The initiation charge material 38 may be deformable with respect to the initiation pyrotechnic material 58 to accommodate or interfere with the supply of initiation pyrotechnic material 58, such that as compressive forces are applied to the materials as the initiator canister 30 is laser welded onto the header body 20, the initiation charge material 38 deforms or compresses. As a result, a contact surface area between the supply of initiation pyrotechnic material 58 and the supply of initiation charge material 38 is created, thereby increasing the initiating contact between the materials. Because the initiation charge material 38 is deformable, there is no compromise of the initiation pyrotechnic material-bridgewire interface caused by an interference of the initiation charge material 38 with the initiation pyrotechnic material 58. The initiation charge material 38 may provide support for the initiation pyrotechnic material 58. Further, in certain preferred embodiments of the invention, the initiation charge material 38 preferably has a relatively lower density than the density of the initiation pyrotechnic material 58. A suitable density for the initiation charge material 38 is about 50% to about 75% of theoretical density, preferably about 60% to about 68%.

Referring to FIG. 2, in an alternate preferred embodiment of the invention, a single pin initiator 210 includes a header body 220, formed from sheet metal preferably using a stamping process, which forms an eyelet 222 at a lip end portion 223 of the header body 220 and a connector shell 225 at an end portion opposing the lip end portion 223. As shown for example in FIG. 2, the lip end portion 223 forms a lip or flat surface that extends radially about a periphery of the eyelet 222. Preferably, the header body 220 is formed of a suitable material, such as a stainless steel material. The eyelet 222 forms a generally cylindrical or barrel-shaped portion of the header body 220 along a longitudinal length of the header body 220 and transitions into a chamber 224 formed or defined by at least a portion of the header body 220, as shown for example in FIG. 2. An initiator canister 230 is connected to the header body 220 using a suitable mechanical connection, for example by laser welding the initiator canister 230 onto the header body 220. The initiator canister 230 forms or otherwise defines a first storage chamber 232, within which can be stored or contained a supply of initiation charge material 238. As shown, the initiator canister 230 can desirably be sized such as to contain therewithin a suitable amount of initiation charge material 238. The supply of initiation charge material 238 may comprise suitable charge materials such as known to those having ordinary skill in the art and guided by the teachings herein provided with such charge materials generally being combustible or ignitable to produce an output charge.

Preferably, the supply of initiation charge material 238 includes zirconium and potassium perchlorate made into a slurry-loaded charge containing a strong binder material, such as an acrylic emulsion. In certain preferred embodiments of the invention, the acrylic emulsion may desirably include materials such as hydroxypropylcellulose for enhancing viscosity of the slurry-loaded charge. With the addition of a low level of hydroxypropylcellulose and additional carrier fluid, for example, the slurry-loaded charge is made less dense, such as to facilitate or increase the deformability of the slurry-loaded charge. Further, the thermal conductivity of the slurry-loaded charge may be enhanced with the addition of at least one thermal conductivity enhancer, such as aluminum powder.

As shown in FIG. 2, a pin 240 is positioned within the eyelet 222 and generally extends along at least a portion of a longitudinal axis A of the single pin initiator 210. The pin 240 is made of an electrically conductive material, which is compatible with the sealing material in such properties as thermal expansion and bonding, such as Carpenter 52 or Inconel alloys, for example. The pin 240 is in electrical communication with a sensor controlled firing circuit (not shown) such as known in the art and such as effective to send a signal to the initiator 210 to effect the desired actuation thereof. The pin 240 includes or forms a head portion 242 that at least partially extends into the first storage chamber 232. Preferably, the pin head portion 242 forms or includes a generally flat or convex smooth surface 243. The pin also includes or forms a body portion 244 that is secured within the eyelet 222. For example, in one preferred embodiment of the invention, the pin body portion 244 is secured within the eyelet 222 by an insulating seal 248, for example a glass seal thereby forming a glass to metal seal. The pin 240 is maintained in spaced relationship with the header body 220 by the seal 248, thereby electrically insulating the pin 240 from the header body 220 while providing suitable physical containment of the pin body portion 244 within the eyelet 222. Other suitable insulating materials may be used to form the seal 248, for example ceramic or plastic composite materials, that provide proper insulating characteristics while maintaining the pin body portion 244 securely positioned within the eyelet 222. A portion of the pin body portion 244 may extend through the seal 248 and into the chamber 224 formed by at least a portion of the header body 220, as shown in FIG. 2.

The generally flat or convex pin head surface 243 provides an area for mechanical connection to or contact with a bridgewire 250. The pin head surface 243 allows for adjustment and control of a length of the bridgewire 250. As shown in FIG. 2, the bridgewire 250 is connected to the lip end portion 223 of the header body 220 using any suitable mechanical connection, such as a resistance weld. The bridgewire 250 spans or extends from the lip end portion 223 of the header body 220 and contacts the pin head portion 242 to form or provide electrical communication between the pin 240 and the header body 220. Preferably, but not necessarily, the bridgewire 250 is suitably connected to the surface 243 of the pin head portion 242, using a conventional mechanical connection, such as by a suitable resistance weld. The bridgewire 250 is in initiating contact with a supply of initiation pyrotechnic material 258. In one embodiment of the invention, the bridgewire 250 is heated by current from a firing circuit to ignite the initiation pyrotechnic material 258. As discussed above, the length of the bridgewire 250 can be controlled as a result of the short distance between the pin 240 and the header body 220, thus preventing disengagement of the bridgewire 250 from the pin 240 and/or the header body 220.

The supply of initiation pyrotechnic material 258 is deposited or disposed on, and preferably bonds to, at least a portion of the bridgewire 250. Thus, the surface 243 of the pin head portion 242 provides a retention mechanism for maintaining at least a portion of the supply of initiation pyrotechnic material 258 properly disposed or deposited onto and adhered to at least a portion of the bridgewire 250. Preferably, but not necessarily, at least a portion of the supply the initiation pyrotechnic material 258 is also at least partially disposed or deposited under the pin head portion 242, and adhered to a portion of the lip end portion 223. By adhering to the pin head portion 242, the lip end portion 223 and/or the glass to metal seal 248, the supply of initiation pyrotechnic material 258 is “locked” in proper position relative to the bridgewire 250, as shown for example in FIG. 2. Additionally, the pin 240 is maintained in proper position along the longitudinal axis A of the single pin initiator 210 and positive contact between the bridgewire 250 and the header body 220 and the bridgewire 250 and the pin 240 is maintained.

In one embodiment of the invention, the supply of initiation pyrotechnic material 258 comprises a slurry-loaded initiation pyrotechnic material. Those skilled in the art and guided by the teachings herein provided will appreciate that various slurry-loaded initiation pyrotechnic materials, such as known in the art, can desirably be used in the practice of the invention. Thus, the broader practice of the invention is not necessarily limited to specific or particular such pyrotechnic materials.

As discussed above, the initiator canister 230 is preferably securely connected to the header body 220 to maintain an initiation contact or communication between the supply of initiation pyrotechnic material 258 and the supply of initiation charge material 238. As shown in FIG. 2, at least a portion of the supply of initiation pyrotechnic material 258 can be in initiating contact with at least a portion of the supply of initiation charge material 238. The initiation charge material 238 may be deformable with respect to the initiation pyrotechnic material 258 to accommodate or interfere with the supply of initiation pyrotechnic material 258, such that as compressive forces are applied to the materials as the initiator canister 230 is laser welded onto the header body 220, the initiation charge material 238 deforms or compresses.

A further advantage of the invention is the elimination of “microwelding,” which plagues conventional designs. Microwelding is electrical discharge welding of the bridgewire to the header in the “setback” area of the header, the space between the bridgewire weld and the glass seal material on a flush bridged unit where the pyrotechnic material is pressed against the header. The electrical discharge occurs when an electrostatic discharge (“ESD”) test is conducted on the unit. The effect of microwelding is to lower the resistance of the bridgewire, which causes the unit to violate the performance specifications after ESD testing. This phenomenon does not occur to a significant extent in units of the present invention because the bridgewire is arched up from the weld, and is not in casual contact with the header for any appreciable distance.

Referring to FIG. 3, there is illustrated a passive restraint system assembly 100 such as having the form of a micro-gas generator and including a single pin initiator 10, as described above with reference to FIG. 1, in accordance with one preferred embodiment of the invention.

As shown in FIG. 3, the passive restraint system assembly 100 includes a gas generant canister 60 positioned over the initiator canister 30 and securely mounted or connected to the single pin initiator 10. Preferably, the gas generant canister 60 is welded to the initiator canister 30 and/or the header body 20 to form a hermetic structural seal. Other suitable mechanical connections may also be used to securely fasten or connect the gas generant canister 60 to initiator cannister 30 and/or the header body 20. The gas generant canister 60 forms or defines a second storage chamber 62 that contains a supply of gas generant material 64. At least a portion of the gas generant material 64 is reactable or combustible to generate a product gas. The supply of gas generant material 64 may be any suitable gas generant material known to those having ordinary skill in the art. Preferably, the supply of gas generant material 64 is in the form of a granular material. However, it is understood that the broader practice of the invention is not necessarily limited to the incorporation and use of particular or specific forms of the gas generant material 64. Thus, other suitable forms of gas generant materials including, for example, tablets, grains and wafers, may be used if desired.

The initiator header body 20 is positionable or mountable relative to a housing 70 and is operatively connected to at least one sensor (not shown) for use in a vehicle. Preferably, the housing 70 forms a bore 72 within which the initiator header body 20 is positioned. The housing 70 provides electrical insulation between the single pin initiator assembly 10 and other components or parts of the passive restraint system assembly 100. The housing 70 may include a variety of compositions including plastic-like compositions that are well-suited for electrical insulation and injection molding. In one embodiment of the invention, the housing 70 is formed or manufactured using a nylon material.

As shown in FIG. 3, the housing 70 and the single pin initiator 10 positioned within the housing 70, are positionable within an insert member 80. With respect to combining the housing 70 and the insert member 80 with the single pin initiator 10, an injection molding process is utilized in which liquid or flowable housing material is disposed about selected portions of the single pin initiator 10 and selected portions of the insert member 80. When the housing material solidifies, the insert member 80 is fixedly held to the housing 70 and the housing 70 is fixedly held to the single pin initiator 10. Preferably, the insert member 80 is an integral one-piece unit forming a free end portion 82 that maintains the housing 70 secured within the insert member 80.

The single pin initiator 10 is in signal receiving communication with one or more sensors (not shown) such as known in the art and such as effective to send a signal to the single pin initiator 10 to effect the desired actuation thereof. The single pin initiator 10 is in reaction-initiating communication with the supply of gas generant material 64 such that actuation of the single pin initiator 10 results or otherwise produces reaction of at least a portion of the supply of gas generant material 64. Such reaction will result in the combustion of at least a portion of the supply of gas generant material 64 to produce a product gas. The product gas passes into the associate passive restraint system.

Method of Operation

Referring to FIG. 3, operation of the passive restraint system assembly 100 begins with at least one sensor sensing an occurrence for which actuation of the passive restraint system assembly 100 is desired. Upon sensing of the occurrence, an electrical actuation signal is delivered to the single pin initiator 10. Electrical communication between the header body 20 and the pin 40 via the bridgewire 50 causes the bridgewire 50 to heat and ignite at least a portion of the supply of initiation pyrotechnic material 58. Upon ignition of at least a portion of the supply of initiation pyrotechnic material 58, at least a portion of the supply of initiation charge material 38 ignites and combusts. The reaction of at least a portion of the initiation charge material 38 results in the subsequent ignition or reaction of at least a portion of the supply of gas generant material 64 contained within the gas generant canister 60 positioned over the initiator canister 30 and securely connected to the header body 20. As described above, such reaction will result in the combustion of at least a portion of the supply of gas generant material 64 to produce a product gas. The product gas passes into the associate passive restraint system.

Although described herein in the context of a micro-gas generator, it will be appreciated by those skilled in the art and guided by the teachings herein provided, that the single pin initiator 10 of the present invention can be appropriately incorporated into other restraint system applications, as may be desired.

Thus, the invention provides a single pin initiator for use in a gas generator device that includes a header body that is easily fabricated or manufactured as a single part. Additionally, the single pin initiator of the present invention includes or forms a pin having a head portion that forms a generally smooth surface to which a bridgewire is connected. The bridgewire provides electrical communication between the pin head portion and the header body. The generally flat smooth surface formed by the pin head portion provides an area for connection of the bridgewire. Since the initiation charge is not pressed or compacted in this design, there is no tendency to breaking of the bridgewire on an uneven surface. This design approach thereby prevents the breaking of the bridgewire and/or damage to the bridgewire-header body connection (by comparison to current practice), and allows for control of a bridgewire length, both through controlling the pin head diameter and by controlling the amount of “setback,” or radial distance from the inner edge of the bridgewire attachment to the lip end portion of the header. Further, the pin partially positioned within an eyelet formed by the header body forms a pin head portion that provides a retention mechanism for maintaining an initiation pyrotechnic material properly positioned within the single pin initiator and in initiating contact with the bridgewire, without the need for additional machined features or components.

The invention illustratively disclosed herein suitably may be practiced in the absence of any element, part, step, component, or ingredient which is not specifically disclosed herein.

While in the foregoing detailed description this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purposes of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.