Inflator with ignition distribution

An inflator includes a housing and a gas generant disposed in the housing for creating a source of inflation gas. An initiator is disposed in the housing for producing a source of energy to ignite the gas generant. A distributor is disposed between the initiator and the gas generant. The distributor defines at least two distinct flow paths for distributing the source of energy to the gas generant.

FIELD

The present disclosure generally relates to airbags. More particularly, the present disclosure relates to an airbag with an ignition distributor for distributing the ignition energy from a single initiator to various surfaces of a gas generant.

BACKGROUND

Inflatable safety restraint devices, or airbags can be found on most new vehicles. A vehicle can include an inflatable curtain airbag, for example. The inflatable curtain airbag can be deployed from a headliner of the vehicle, and can inflate to protect the head of the occupant(s) from contact with the side of the vehicle, such as the windows.

Airbags can typically include an inflator that can be connected to the one or more airbags positioned within the vehicle. The inflator can rapidly produce a quantity of inflation fluid or gas that can fill the airbag to protect the occupant(s). A typical inflator generally includes a gas generant for generating the inflation gas and an igniter system for producing a source of energy to ignite the gas generant. The igniter system can include multiple reactive charges for igniting the gas generant, depending on the particular application.

While known ignition systems may have proven satisfactory for their intended applications, a continuous need for improvement in the pertinent art remains. For example, it may be desirable to more efficiently direct the ignition energy from a single reactive charge to the gas generant.

SUMMARY

In accordance with one aspect, the present teachings provide an inflator for an airbag. The inflator includes a housing and a gas generant disposed in the housing for producing a source of inflation gas. An initiator is disposed in the housing for producing a source of energy to ignite the gas generant. A distributor is disposed between the initiator and the gas generant. The distributor defines at least two distinct flow paths for distributing the source of energy to the gas generant.

In accordance with another aspect, the present teachings provide an inflator for delivering a source of inflation gas to a side airbag of a motor vehicle. The inflator includes an elongated housing having a generally cylindrical cross section. A gas generant for producing the source of inflation gas includes first and second generally planar sides and an opening extending therethrough. An initiator is disposed in the housing for producing a source of energy to ignite the gas generant. A distributor is disposed between the initiator and the gas generant. The distributor includes a main opening for directing the source of energy to the opening of the gas generant and at least one secondary opening for directing the source of energy to one of the first and second planar sides of the gas generant, or to internal or external surfaces of the gas generant.

In accordance with a further aspect, the present teachings provide an inflator for an airbag of a motor vehicle. The inflator includes a housing and a gas generant for producing a source of inflation gas. The gas generant is disposed in the housing in a predetermined orientation. An initiator is disposed in the housing for producing a source of energy to ignite the gas generant. A distributor is disposed between the initiator and the gas generant. The distributor defines at least first and second distinct flow paths for distributing the source of energy to the gas generant. The first distinct flow path is oriented relative to the gas generant to direct the source of energy to a first surface of the gas generant. The second distinct flow path is oriented relative to the gas generant to direct the source of energy to a second surface of the gas generant.

DESCRIPTION OF VARIOUS ASPECTS

With initial reference toFIG. 1, a portion of an exemplary motor vehicle10including an airbag system12in accordance with the present teachings is illustrated. The airbag system12can include one or more airbags16and an inflator18. As various airbags16known in the art could be employed with the inflator18, such as a front impact airbag, a knee bolster, an inflatable curtain, or an overhead airbag, the airbag16will not be discussed in great detail herein. Briefly, however, with reference toFIG. 1, the airbag16may include a cushion20, which can be stored within a trim panel of the motor vehicle10. In this example, the airbag16is a side impact inflatable curtain airbag, which when inflated by the inflator18occupies a large volume of a passenger cabin in the motor vehicle10as illustrated inFIG. 1.

With continued reference to the environmental view ofFIG. 1and additional reference toFIGS. 2 through 4, the inflator18of the present teachings will be further described. Generally, the inflator18may be operative to create a rapidly expanding gas that can inflate the airbag16within milliseconds of detection of a predetermined event (e.g., impending vehicle rollover) of the motor vehicle10to enable the airbag16to inflate and create a barrier between occupant(s) of the motor vehicle10and the motor vehicle10itself, which may prevent or minimize injuries to the occupant(s). The inflator18may generally include a housing22, a gas generant24, and an ignition distribution system26.

The housing22may be an elongated housing having a generally cylindrical cross section or other cross section of suitable geometry. In one particular application, the housing has a length L of approximately 100-200 mm and a diameter D of approximately 20-30 mm. It will be understood that the noted dimensions are merely exemplary and may deviate for different applications within the scope of the present teachings. In one particular embodiment, the housing may have a length of 150 mm and a diameter of 20 mm.

The distribution system26may be crimped into an end of the housing22in a conventional manner or otherwise suitably secured within the housing22. The ignition distribution system26may generally include an actuator in the form of a pyrotechnic initiator27. The initiator27is shown in simplified cross-sectional form throughout the drawings and may include any suitable initiator. One suitable initiator is shown and described in commonly assigned U.S. Pat. No. 7,210,703, which is hereby incorporated by reference in its entirety. As such, the exemplary initiator27will not be discussed in detail herein. Briefly, however, the initiator27may include a reactive charge, a pair of conductive pins and a bridgewire (not specifically shown). The squib can produce a detonation or ignition charge upon receipt of a signal, such as an electrical current, as will be discussed. The reactive charge may be in communication with the gas generant24. The reactive charge may also be in communication with and responsive to the squib to ignite upon receipt of the charge from the squib.

One of the conductive pins may be isolated from the squib, while the other conductive pin may be coupled to the squib. The bridgewire can connect the first conductive pins. Additional reactive charge can also be packed about the bridgewire, if desired. Upon receipt of a signal, an electrical current may be introduced to the pins. The signal may be indicative of an impending collision or other vehicle event in which inflation of the cushion20is desired, for example. The introduction of the electric current may cause the squib to fire, and produce an ignition charge, which in turn, may ignite the reactive charge. Sensing of the vehicle event and the transmission of the corresponding signal to the initiator27will be understood to be conventional insofar as the present teachings are concerned.

The gas generant24may include one or more discrete elements24a. The discrete element(s)24amay be disposed within the housing22in a predetermined orientation. In this regard, the element(s)24aof the gas generant24are not pellets which are randomly disposed within the housing22. Rather, the discrete element(s)24amay be particularly oriented within the housing22to more effectively tune performance characteristics of the inflator18.

In certain applications, the gas generant24comprises a monolithic gas generant grain. Examples of suitable gas generants are described in commonly owned U.S. Ser. No. 11/472,260 filed 21 Jun. 2006, which is hereby incorporated by reference as if fully set forth herein. It will be understood, however, that another gas generant may be employed within the scope of the present teachings.

The gas generant24may be generally cylindrical or of any other desired shape. Each of the discrete element(s)24amay include a first and second parallel side or end face28. One of the first and second end faces28may be oriented to face toward the initiator27. Each of the element(s)24amay further include a bore30passing therethrough. The bore30may generally be formed or defined about a longitudinal axis defined by the discrete element(s)24a. The discrete element(s)24amay be stacked within the housing22such that the respective bores30substantially align. The bores30may have any desired shape, but may generally have a circular cross section defined by a sidewall31. In addition, the bores30may be of any suitable size to enable a desired ignition and a desired rate of gas generation. As an example, the bores30may have a diameter from about 4.5 millimeters to about 7.0 millimeters. The gas generant24may be held in place with a plug32. The plug32may be conventional insofar as the present teachings are concerned. Briefly, the plug32may include a plurality of apertures for the passage of inflation gas.

The inflator18may additionally include a conventional filter34. The filter34may be mounted in an end36of the housing22. As shown, the end36may be crimped to retain the filter34. The end36of the housing22may include a plurality of openings38for venting the inflation gas from the housing22to the cushion20. In this regard, the inflation gas passes from a central opening40of the filter34, through the filtering media of the filter34and out the plurality of openings38.

The distribution system26may further include a distributor42disposed between the initiator27and the gas generant24. The distributor42may be generally cylindrical in shape and may define at least two distinct flow paths for distributing the source of energy produced by the initiator27to the gas generant24. The at least two distinct flow paths may include a central opening44and a plurality of secondary openings46positioned radially relative to the central opening44. The central opening44may be larger than the secondary opening46. In one particular application, the central opening44may have a diameter approximately 5 mm and the secondary openings46may have a diameter of approximately 3 mm. The central opening44may be disposed relative to the gas generant24to direct the source of energy to a first surface of the gas generant24defined by the sidewall31of the bore30. The secondary openings46may be oriented relative to the gas generant24to direct the source of energy to a second surface comprising the end face28of the adjacent discrete element24aof the gas generant24.

Turning to the cross-sectional view ofFIG. 5, another inflator in accordance with the present teachings is illustrated and identified at reference character110. Given the similarities between the inflator18and the inflator110, like reference numerals will be used to identify similar elements. The inflator110differs from the inflator18, for example, in that the housing22includes a plurality of modular components.

In the embodiment illustrated, the plurality of modular components of the housing22may include first and second stampings112and114. The first stamping112may be a combustion chamber stamping into which the initiator27may be directly molded. The first stamping112may be a polymer. In this manner, conventional crimping and sealing of the initiator end of the housing22may be effectively eliminated.

The second stamping114may be a cooling chamber stamping. The cooling chamber stamping114may be formed to include an orifice116sized for controlling combustion pressure. The cooling chamber stamping114may further include a stepped wall118to accommodate a resistance weld of the cooling chamber stamping114to the combustion chamber stamping112.

A hermetic seal (not shown) may be provided over the orifice116in the form of a foil tab prior to resistance welding of the housing stampings112and114. The filter34may be held in place in the cooling chamber stamping114with a roll crimp. Hermetic sealing of the openings38is not required. Modular construction of the housing22provides for simplified hermetic sealing of the inflator110and a reduction in manufacturing steps. To the extent not otherwise described, the construction and operation of the inflator110will be understood to be identical to the description provided above for the inflator18.

It will now be apparent that the present teachings provide for an arrangement for efficiently directing a single source of energy toward the gas generant24. Performance characteristics of the inflators18and110may be modified through changes to the gas generant24and the openings44and46in the distributor42, for example.

While specific examples have been described in the specification and illustrated in the drawings, it will be understood by those skilled in the art that various changes may be made and equivalence may be substituted for elements thereof without departing from the scope of the present teachings as defined in the claims. Furthermore, the mixing and matching of features, elements and/or functions between various examples may be expressly contemplated herein so that one skilled in the art would appreciate from the present teachings that features, elements and/or functions of one example may be incorporated into another example as appropriate, unless described otherwise above. Moreover, many modifications may be made to adapt a particular situation or material to the present teachings without departing from the essential scope thereof. Therefore, it may be intended that the present teachings not be limited to the particular examples illustrated by the drawings and described in the specification as the best mode of presently contemplated for carrying out the present teachings but that the scope of the present disclosure will include any embodiments following within the foregoing description and any appended claims.