Patent Description:
Inflatable occupant restraint systems, including airbags, are commonly included on motor vehicles for passive occupant protection. Airbags used for frontal impact protection are generally installed in the vehicle steering wheel for the driver and behind the vehicle instrument panel for other front seat occupants. In addition to frontal impact protection, inflatable restraints are used for occupant protection from side impacts. For example, side curtain airbags are typically mounted along the roof rail of a vehicle and deploy in a downward direction to provide an energy absorbing structure between the head and upper torso of an occupant and the vehicle interior components. Side airbags may also be carried by a vehicle seat.

Inflator devices are employed to produce or supply inflation gas for inflating an inflatable airbag in the event of a collision. The inflator devices for such applications often include a gas generant material stored within the housing of the inflator device and an initiator to actuate the gas generant material when a sensor within the vehicle senses an accident condition (e.g., measures abnormal deceleration). Actuation of the gas generant material triggers inflation of the airbag within a few milliseconds with the produced gas. The inflated airbag cushions the vehicle occupant from impact forces. Initiators are also used for the pretensioning of seatbelts.

Initiators may commonly have a first or primary pyrotechnic material and a second or secondary pyrotechnic material. The primary pyrotechnic material is ignited by an electrical signal and in turn ignites the secondary pyrotechnic material. Heat from combustion of the secondary pyrotechnic material ignites gas generant material of the inflator device to produce inflation gases for an airbag.

While known initiators for inflatable occupant restraints have generally proven to be suitable for their intended uses, a continuous need for improvement in the relevant art remains. In these regards, it is desirable to eliminate or minimize performance shifts of an initiator that may result from chemical incompatibility between primary and secondary pyrotechnic materials. Document <CIT> relates to an igniting unit, especially for an inflator, comprising an electric igniter having a first inner cap which forms a space for being filled with a booster propellant charge with a second outer cap.

It is one general object of the present teachings to provide an initiator for a gas generator of a vehicle safety device, as in claim <NUM>, that hermetically separates a primary pyrotechnic material from a secondary pyrotechnic material.

In accordance with one particular aspect, the present teachings provide an initiator for a gas generator of a vehicle safety device which includes a cup defining an interior, a primary pyrotechnic material disposed in the interior of the cup, and a secondary pyrotechnic material disposed in the interior of the cup. A separator member hermetically separates the primary pyrotechnic material from the secondary pyrotechnic material.

In accordance with another particular aspect, the present teachings provide an initiator for a gas generator of a vehicle safety device. The initiator includes a cup, a base member, and a separator member. The cup defines an interior and includes a closed end, an open end, and a cylindrical sidewall extending therebetween. The base member is at least partially disposed in the cup. The base member includes an axially extending opening having a portion containing a first pyrotechnic material. The cylindrical sidewall of the cup is attached to the base member about a circumference of the base member. A second pyrotechnic material is disposed in the interior of the cup. The separator member is attached to the base member and closes one end of the axially extending opening to hermetically separate the first pyrotechnic material from the second pyrotechnic material.

One or more example embodiments will now be described more fully with reference to the accompanying drawings. The one or more example embodiments are provided so that this disclosure will be thorough and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth, such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, and that the example embodiment should not be construed to limit the scope of the present disclosure. Well-known processes, well-known device structures, and well-known technologies are not described herein in detail.

The phrases "connected to", "coupled to" and "in communication with" refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components may be coupled to each other even though they are not in direct contact with each other. The term " adjacent" refers to items that are in close physical proximity with each other, although the items may not necessarily be in direct contact. The phrase "fluid communication" refers to two features that are connected such that a fluid within one feature is able to pass into the other feature. "Exemplary" as used herein means serving as a typical or representative example or instance, and does not necessarily mean special or preferred.

With reference to drawings, an initiator for a gas generator of a vehicle safety device in accordance with the present teachings is illustrated and generally identified at reference character <NUM>. The initiator <NUM> may be part of an occupant restraint system of a motor vehicle that includes a gas generator and an inflatable airbag (not particularly shown), for example. The particular inflator or pyrotechnical inflator <NUM> shown in the drawings is particularly adapted for a driver side front airbag of an occupant restraint system. It will be understood, however, that the initiator described herein can be used in many other pyrotechnical devices within the scope of the present teachings. It will be understood, however, that various aspects of the present teachings may be readily adapted for use with other airbags or with seatbelt pretensioners.

The initiator <NUM> is generally illustrated to include a cup or case <NUM>, a first or primary pyrotechnic material, and a second or secondary pyrotechnic material <NUM>. The primary and secondary materials are disposed or stored in an interior <NUM> of the cup <NUM>. The cup <NUM> includes a cylindrical sidewall <NUM> and a circular base. The cylindrical sidewall <NUM> that extends along an axis A of the initiator <NUM> between a closed end <NUM> and an open end <NUM>. The cup <NUM> may be formed of metal and may be formed by cold striking. In one particular example, the cup <NUM> may be formed by stamping a sheet of nickeled steel, such as DC04 or DC06 and may have a thickness between <NUM> and <NUM>.

The cup <NUM> is preferably formed to include a plurality of weakened zones <NUM>. As will become more fully understood below, the weakened zones <NUM> of the cup <NUM> open in response to a pressure from within the cup <NUM> generated by combustion of the secondary pyrotechnic material <NUM>. In the embodiment illustrated, the sidewall <NUM> includes four weakened zones <NUM> uniformly distributed around the axis A. The plurality of weakened zones <NUM> can be varied in configuration or number within the scope of the present teachings.

In the embodiment illustrated, the first pyrotechnic material <NUM> is distinct from the secondary pyrotechnic material <NUM>. The primary pyrotechnic material <NUM> may be separated from the secondary pyrotechnic material <NUM> within the interior <NUM> of the cup <NUM> by a separator member <NUM>. The primary pyrotechnic material <NUM> may be in the form of a slurry. The secondary pyrotechnic material <NUM> may be a granulated material, including but not limited to a boron based material. It will be understood the particular pyrotechnic materials are outside of the scope of the present teachings and may be selected from various pyrotechnic materials well known in the art.

The initiator <NUM> of the present teachings may further include an adaptor or base member <NUM>. The adaptor <NUM> functions to contain the first pyrotechnic material <NUM> and to provide an interface between the cup <NUM> and the separator member <NUM>. The adaptor <NUM> may be formed of stainless steel or other suitable material. One suitable material is Type <NUM> stainless steel. The adaptor <NUM> is cylindrical in shape and includes a stepped configuration having a first or lower portion <NUM> and a second or upper portion <NUM>. The first portion <NUM> has a first diameter and the second portion <NUM> has a smaller, second diameter.

The adaptor <NUM> is at least partially disposed in the cup <NUM>. As shown, the adaptor <NUM> is completely or substantially completely disposed in the cup <NUM>. The adaptor <NUM> is sized to be received within the open end <NUM> of the cup <NUM>. The cylindrical sidewall <NUM> of the cup <NUM> may be attached to the adaptor <NUM> about a circumference of the adaptor <NUM>. In the embodiment illustrated, the first portion <NUM> of the adaptor <NUM> may be welded to the cup <NUM>.

The first portion <NUM> of the adaptor <NUM> defines a central opening <NUM> that receives an ignition device <NUM>. The ignition device <NUM> conventionally includes a pair of electrical connectors or pins <NUM> and a bridge wire <NUM>. The pair of electrical pins <NUM> are in reaction initiating communication with the first pyrotechnic material <NUM> through the bridge wire <NUM>. In this regard, an electrical current delivered to the pins <NUM> will serve to melt the bridge wire <NUM> and ignite the first pyrotechnic material <NUM>.

The second portion <NUM> of the adaptor <NUM> defines a central cavity <NUM>. The cavity <NUM> contains the primary pyrotechnic material <NUM>. The cavity has an open end that is closed by the separator member <NUM>. The separator member <NUM> hermetically separates the primary pyrotechnic material <NUM> from the secondary pyrotechnic material <NUM>. As used herein, the term "hermetically" describing the separation between the primary and secondary pyrotechnic materials <NUM> and <NUM> shall mean that the primary and secondary materials <NUM> and <NUM> are completely sealed from one another. The hermetic seal between the primary pyrotechnic material <NUM> and the secondary pyrotechnic material <NUM> provides a mechanical separation that eliminates or substantially eliminates any chemical incompatibility between the primary pyrotechnic material <NUM> from the secondary pyrotechnic material <NUM> that may otherwise degrade or shift performance of the initiator <NUM>.

As particularly shown in <FIG> and <FIG>, the separator member <NUM> includes a cylindrical sidewall <NUM>. The cylindrical sidewall <NUM> extends along the axis A of the initiator <NUM> between a closed end <NUM> and an open end <NUM>. The closed end <NUM> defines a disk-shaped portion. The separator member <NUM> may be formed of metal and may be formed by cold striking. In one particular example, the separator member <NUM> may be formed by stamping a sheet of stainless steel. The cylindrical sidewall <NUM> of the separator member <NUM> may be welded or otherwise securely attached to the second portion <NUM> of the adaptor <NUM>. While the separator member <NUM> is shown and described as being cylindrical, the separator member may alternatively be disk only in shape (i.e., not including the sidewall <NUM>). With such an alternative shape, the separator member <NUM> may be welded or otherwise suitably attached to the upper axial end of the second portion <NUM> of the adapter <NUM>.

The closed end or disk-shaped portion <NUM> of the separator member <NUM> may be formed to include a weakened zone <NUM>. The weakened zone <NUM>, which may be stamped into the disk-shaped portion <NUM>, is configured to open in response to a pressure in the cavity <NUM> of the adapter <NUM> generated by combustion of the first pyrotechnic material <NUM>. In the embodiment illustrated, the weakened zone <NUM> includes a plurality of radially extending arms <NUM>. The arms <NUM> are shown to originate from a common point <NUM> at a radial center of the disk-shaped portion <NUM>. The configuration of the weakened zone <NUM> may vary within the scope of the present teaching.

The initiator <NUM> of the present teachings is shown to further include an insulated resistance cover or static cover <NUM> and an elastomeric overmolding or overmolded member <NUM>. These elements <NUM> and <NUM> will be understood to be conventional insofar as the present invention is concerned. Briefly, the overmolded member <NUM> may be an injection mold of a glass filled nylon <NUM> material. The static cover <NUM> may be constructed of nylon <NUM> or other plastic material.

Claim 1:
An initiator (<NUM>) for a gas generator of a vehicle safety device, the initiator (<NUM>) comprising:
a cup (<NUM>) defining an interior;
a primary pyrotechnic material (<NUM>) disposed in the interior of the cup (<NUM>);
a secondary pyrotechnic material (<NUM>) disposed in the interior of the cup (<NUM>);
a separator member (<NUM>) hermetically separating the primary pyrotechnic material (<NUM>) from the secondary pyrotechnic material (<NUM>); and
an ignition device (<NUM>) including a pair of electrical connectors or pins (<NUM>) and a bridge wire (<NUM>);
a static cover (<NUM>) covering the cup (<NUM>);
an overmolded member (<NUM>) attaching the static cover (<NUM>) and the ignition device (<NUM>);
wherein the initiator (<NUM>) is further comprising an adaptor (<NUM>) at least partially disposed in the interior of the cup (<NUM>), the adaptor (<NUM>) holding the primary pyrotechnic material (<NUM>) and being distinct from the ignition device (<NUM>), the separator member (<NUM>) being connected to the cup (<NUM>) through the adaptor (<NUM>).