Multi-stage inflator with sympathetic ignition enhancement device

Cross-reference to related applications This application claims the benefits of provisional application number 60 / 539,801 filed on 28 January 2004 and provisional application number 60 / 541,089 filed on 2 February 2004.

Background Technique of the Present Invention The present invention incorporates an inflator for vehicle airbags, and more particularly, a device having multiple chambers that facilitates sympathetic ignition of the propellant charge in one of the inflator chambers. But about the inflator.

Some inflator designs incorporate multiple conversion chambers, each containing a predetermined amount of gas-producing material stored in each chamber. Many of these inflators are designed so that the combustion of gas-producing material in one chamber initiates the harmonious combustion of gas-producing material in another chamber. In the existing design, the ignition sequence of the gas-producing material is controlled by a separate igniter in contact with each chamber. The equipment of the igniter and associated support structure in each chamber significantly increases the bulk, complexity and manufacturing cost of the inflator.

Abstract of the invention According to the present invention, the first chamber containing a predetermined amount of the first combustible material, the second chamber containing a predetermined amount of the second combustible material, and the first chamber containing a predetermined amount of the second combustible material are harmonized according to the combustion of the first combustible material. An airbag inflator is provided that includes a thermally conductive igniter for igniting a second combustible material. The igniter has thermal communication with both the first and second flammable material. The heat from the combustion of the first combustible material is transferred along the igniter, causing the ignition of the second combustible material.

In one embodiment, the first flammable material comprises a first gas-producing composition and the second flammable material comprises a second gas-producing composition. The igniter also contains a thermally conductive member and an auto-ignition material that is activated by heat that is thermally communicated with the thermally conductive member. The harmonious ignition of the second gas-forming composition is caused by the ignition of the spontaneously igniting material due to the heat from the combustion of the first gas-forming composition transmitted along the members of thermal conductivity.

In another embodiment, the first flammable material comprises a first gas-producing composition and the second flammable material comprises a heat-activated self-igniting material. The igniter also includes a member of thermal conductivity. The harmonious ignition of the spontaneously igniting material is caused by the heat from the combustion of the first combustible material transmitted along the members of thermal conductivity.

Detailed explanation FIG. 1 is a cross-sectional view of one embodiment of the inflator 10 of the present invention. The inflater 10 is primarily intended for use in passenger-side inflatable restraint systems in motor vehicles known in the art; however, it is not limited thereto. The components of the inflator 10 can be manufactured from known materials by known processes.

The inflator 10 includes an elongated cylindrical inflator body 12 that defines the enclosure. The inflator body 12 can be cast, stamped, extruded, or otherwise metal-molded. The end caps 26 and 28 are securely attached to the opposing ends of the inflator body 12 and close the ends of the inflator body using one or more known methods. In FIG. 1, the ends of the inflator body 12 are crimped over the first and second caps 26, 28, and the caps are firmly attached inside the inflator body. The inflator body 12 is generally provided with a plurality of expanding gas outlet openings 50 spaced along the inflator body 12 to allow fluid communication between the inside of the inflator and the outside of the inflator.

The inner wall 14 is located within the inflator body 12 approximately in the middle of both ends thereof, defining the first and second inflator chambers 20 and 30, respectively. The wall 14 is preferably made of metal or ceramic and is oriented along a plane perpendicular to the longitudinal axis 11 of the inflator body 12. The wall 14 is firmly attached within the inflator body 12 by roll-crimp or other means and within the inflator body when the wall is exposed to the pressure generated by the combustion of the gas-producing material stored in the inflator body. Make sure the wall is maintained in that position. In a preferred embodiment, the wall 14 is a substantially cylindrical member with a central opening 15.

A predetermined amount of the first propellant or gas-producing composition 16 is placed in the chamber 20, and a predetermined amount of the second gas-producing composition 17 is placed in the chamber 30. Any suitable propellant can be used. Typical compounds are also disclosed, for example, in US Pat. Nos. 5,872,329, 6,074,502 and 6,210,505. These patents are referenced and incorporated as part of this specification. The compositions described in these patents illustrate, but are not limited to, gas-producing compositions useful for the applications described herein.

See Figure 1 again. The end cap 26 supports the igniter 62 and is arranged so that the igniter can ignite the first gas-producing composition 16 in the chamber 20 in a known manner. The illustrated positions and orientations of the igniter 62 can be changed according to space and manufacturing requirements without departing from the scope of the invention. Further, the igniter 62 does not need to be placed in the inflator body 12. One example of an igniter suitable for the use described herein is disclosed in US Pat. No. 6,009,809. This patent is referenced and incorporated as part of this specification. Other igniters that can be mounted to have contact with chamber 20 can also be used.

According to the present invention, a thermally conductive igniter is provided to ignite the second combustible material in a harmonious manner in response to the combustion of the first combustible material. The igniter is in thermal communication with both the first and second flammable material. The heat from the combustion of the first combustible material is transferred along the igniter to generate the ignition of the second combustible material.

See Figure 1 again. In a particular embodiment, the first flammable material comprises a first gas-producing composition 16 and the second flammable material comprises a second gas-producing composition 17. The igniter also includes a thermally conductive member 40 and a thermally activated self-igniting material 25 thermally communicated to the thermally conductive member 40. The harmonious ignition of the second gas-forming composition 17 is the ignition of the spontaneously igniting material 25 due to the heat from the combustion of the first gas-forming composition 16 transmitted along the member 40 of thermal conductivity. Produced by.

The thermally conductive harmonious igniter 40 is preferably located adjacent to the wall 14 and, by transferring heat between them, a first gas-forming composition 16 disposed in chamber 20 and in chamber 30. Facilitates harmonious ignition between the placed second gas-producing composition 17. In general, the device 40 is in thermal communication with both the first and second gas-producing material compositions. As used herein, the term "heat-contacted" means that the elements in a heat-contacted relationship can receive or transfer heat to each other.

In the embodiment shown in FIG. 1, the device 40 includes a substantially circular head 41 and a thermally conductive member having a shaft 42 formed integrally with the head 41 and extending from the axial direction of the head 41.

The device 40 provides an exposed surface area (along the head 41) in the chamber 20. In the embodiment shown in FIG. 1, the head 41 is in the form of a relatively thin plate having a substantially constant thickness. This configuration of the head 41 provides relatively rapid heating of the head 41. The device 40 also provides thermal communication between chambers 20 and 30 primarily via the shaft 42. The igniter head 41 and shaft 42 are made of a thermally conductive metal material. Suitable thermal conductive materials are known to those of skill in the art. The preferred metal is copper. Aluminum can also be used.

In different embodiments, the head 41 and shaft 42 of the device 40 can be formed with different shapes and sizes. For example, different shapes or relatively larger or smaller relative sizes of the head 41 may be desirable when using different inflator designs or different types of propellants.

A predetermined amount of the ignition compound 25, such as a heat-activated self-ignition compound known in the art, is preferably located in contact with or near the tip 41 of the shaft extending into the chamber 30. To. The spontaneous ignition substance 25 is a pyrotechnic substance that is ignited by exposure to a temperature lower than the ignition temperature of the second gas-producing composition 17 arranged in the chamber 30. When ignited, the spontaneously igniting material 25 produces a hot gas / particulate effluent. Suitable spontaneous ignition materials are known to those of skill in the art. Examples of suitable self-igniting materials are nitrocellulose-based compositions and black powder.

In a different embodiment of the igniter, the first flammable material comprises a first gas-producing composition 16. The second flammable material contains the heat-activated self-igniting material 25. The igniter also includes a thermally conductive member 40. The harmonious ignition of the self-igniting material 25 is caused by the heat from the combustion of the first gas-producing material 16 transmitted along the member 40 of thermal conductivity.

In another different embodiment (not shown), the thermally activated self-igniting compound is omitted and the portion of the igniter shaft 42 is in direct contact with the second gas-producing composition 17. In this embodiment, the conversion temperature of the first gas-producing composition and the heat conduction characteristics of the head 41 and the shaft 42 of the igniter are such that the portion of the shaft in contact with the second gas-producing composition is a self-igniting substance. It should be specified to be heated to a temperature sufficient to ignite the second gas-producing material without use.

Returning to FIG. 2, a second embodiment 110 of the inflator of the present invention is shown. In Figure 2, numbers similar to those in Figure 1 are used to indicate similar elements. The inflater 110 is a disc-type inflator, as is commonly used in driver-side inflatable restraint systems; however, it is not limited thereto. The inflator 110 includes a metal inflator body 112, such as formed from a pair of nested cups, and further includes an internal wall 114, inside the inflator 110 with first and second chambers 120 and 130. Divide into. In the embodiment shown in FIG. 2, the inflator body 112 is formed by joining or welding two sections 124 and 126 in a nested relationship with each other. Section 124 supports an igniter 162 arranged so that the first gas-producing material in chamber 120 can be ignited in a known manner. The wall 114 is preferably formed of metal or ceramic and is oriented in a plane perpendicular to the longitudinal axis 111 of the inflator body 120.

Similar to the wall 114 in FIG. 1, the wall 114 is firmly anchored within the inflator body 112 (eg by welding) and when exposed to the pressure generated by the combustion of the gas-producing material stored within the inflator body. The wall is kept in place in the inflator body. In a preferred embodiment, the wall 114 is a substantially cylindrical member with a central opening 115. Similar to the inflator 110 of FIG. 1, the chamber 120 of the inflator 110 contains a predetermined amount of the first gas-producing composition 116 and the chamber 130 contains a predetermined amount of the second gas to supply the expansion gas to the vehicle airbag. Contains the product composition 117. The ignition booster 140 is provided within the inflator 110 and preferably includes members of a configuration similar to the device 40 shown in FIG. 1, including a head 141 and a shaft 142 integrally formed and extending axially from the head 141. .. The components of the inflator 110 can be manufactured from known materials and by known processes.

In operation, both of the above inflator embodiments work in a similar fashion. If deployment of a vehicle inflatable restraint system is desired, activation signals are sent to igniters 62, 162 operably combined with first chambers 20, 120 of inflatables 10, 110. The first gas-producing substances 16 and 116 arranged in the first chamber 20 are ignited either directly or via a booster propellant, as is known in the art. Ignition of the first gas-producing material causes the rapid generation of hot expansion gas in the first chambers 10, 110. The heat generated during combustion is transferred to the second chambers 30 and 130 via the ignition devices 40 and 140. In a preferred embodiment, relatively rapid heating of devices 40, 140 causes combustion of spontaneous ignition compounds 25, 125. Combustion of spontaneous ignition compounds 25, 125 causes ignition of the second gas-producing substances 17, 117 located in the second chambers 30, 130, and rapidly explodes the expanding gas for the combined inflatable restraint system. Occur. The double chamber design combined allows for the special deployment characteristics of the airbag system. Typical, but not limited to, two-stage inflator designs and operations are described in US Patent Application No. 10 / 335,786. These patents are referenced and incorporated as part of this specification.

In another aspect shown in FIG. 3-5, the present invention provides a method of manufacturing an inflator and a harmonious ignition improver incorporated therein. The manufacturing process is illustrated for an inflator 210, which is similar to the inflator shown in FIG. However, it is understood that the methods described herein are equally applicable to those shown in FIG. 2 and to other types of inflator designs, including the types of inflators described above. To.

See Figure 3. In a typical manufacturing process, the slag material 240 is placed in the inflator body 212 adjacent to the wall 214 during assembly. The slag material 240 used to form the harmonious ignition improver is placed adjacent to the inner wall 214. A specially designed coining press with coining tools A'and B'is provided to form the slug 240 into the desired shape with head 241 and shaft 242, as substantially shown in FIG. Slag. Tools A'and B'preferably include inwardly extending molded surfaces 340A and 340B that facilitate pressing the slag 240 into the desired shape.

See Figures 4 and 5. The first and second tools A'and B'are engaged at the same time as the coin inner surface 214 to form the slag material 240. In particular, when tools A'and B'are engaged, a pair of protrusions 350 on each tool A'and B'provides a coining function, with respect to the outer wall of the inflator body 212 and the inner wall 214. Pushes the portion of the wall outward in the radial direction, thereby improving the holding power of the wall 240 in the inflator. During production, tools A'and B'are preferably moved together from opposite sides of wall 214, pressing wall 214 and slag material 240 in between. Since the slag 240 is preferably made from a relatively malleable material such as copper or aluminum, the squeezing force of tools A'and B'has a shape that substantially follows the mold surfaces 340A and 340B. Push in the slag material. During compression of the slag 240, some of its constituents tend to pass through or extend through the opening 215 of the wall 214.

The manufacturing process therefore provides a surface area on the head 241 which can transfer the heat of combustion of the first chamber 220 in the inflator to the second chamber 230 via the shaft 242. The process further provides coining of the wall 214, extrusion / molding of the device 240, and further forging of the wall 214 and the device 240 together. A predetermined amount of spontaneous ignition material (not shown) can then be placed in the vicinity of shaft 242 to facilitate ignition of the propellant charge in chamber 230, as described above. The described process minimizes the cost and time normally required to form new parts, provides a relatively strong seal between each inflator chamber, and risks a gas seal failure during airbag deployment. cut back.

See Figure 6. Any of the embodiments of devices 40, 140 described above can be incorporated into the inflator used in the vehicle occupant restraint system 200. The vehicle occupant restraint system 200 has at least one airbag 202 and inflators 10, 110 coupled to the airbag 202 to allow fluid communication with the interior of the airbag. As described above, the inflator 10 comprises a first chamber (not shown) containing a predetermined amount of the first gas producing composition (not shown), a predetermined amount of the second gas producing composition (not shown). It includes a second chamber (not shown) containing (not shown) and a device (not shown) for igniting the second gas-producing composition in response to combustion of the first gas-producing composition. As described above, the igniter communicates with a heat-activated self-igniting substance (not shown) that communicates with the second gas-producing composition, heat that communicates with both the first gas-producing composition and the self-igniting compound. Includes conductive members (not shown). The vehicle occupant restraint system 200 can operate with the collision sensor 211 connected to a known crash sensor algorithm that signals the activation of the vehicle occupant restraint system 200, for example by activating the airbag inflators 10 and 110 in the event of a collision. Can be connected. By providing improved harmonious ignition of the propellants in the second chambers 30, 130, the present invention requires a separate initiator device for each inflator chamber in many existing designs. To avoid. In addition, the heat flow between the chambers is improved. It improves the timing and reliability of inflator performance for many known designs. Although the present invention has been described with respect to a two-stage inflator design, it is understood that the ignition improvers 40, 140 disclosed herein can be incorporated into other inflator designs, such as a three-stage inflator design.

The present invention finds primary use in side impact or head curtain airbag systems, but the use is not limited thereto. It will be appreciated that the description of embodiments of the present invention is for illustrative purposes only. As such, the various structural and operational aspects disclosed herein can be modified by those skilled in the art without departing from the scope of the present invention.

The drawings illustrate embodiments of the present invention:<figref num="1">FIG. 1 is a side view of a cross section of a first embodiment of the inflator of the present invention;</figref><figref num="2">FIG. 2 is a side view of a cross section of a second embodiment of the inflator of the present invention;</figref><figref num="3">FIG. 3 is a cross-sectional side view of a portion of the inflator showing one step of the method of manufacturing the inflator of the present invention;</figref><figref num="4">FIG. 4 is a cross-sectional side view of a portion of the inflator shown in FIG. 3, showing a further step in the method of manufacturing the inflator of the present invention;</figref><figref num="5">FIG. 5 is a cross-sectional side view of a portion of the inflator shown in FIG. 4, showing a further step in the method of manufacturing the inflator of the present invention;</figref><figref num="6">FIG. 6 is an overview representation of a typical vehicle occupant restraint system incorporating the inflator of the present invention.</figref>