Two-stage inflator

Abstract

A dual stage inflator (10) for an inflatable vehicle safety device includes a second stage combustion cup (46) having a first member (68) and a second member (70) formed separately from one another and cooperating to define an interior (64) for receiving a second stage gas generant material.

Description

Technical Field

[0005]

[0001] The present disclosure generally relates to an inflator for providing inflation gas for an inflatable vehicle safety device such as an inflatable airbag. More specifically, the present disclosure relates to a two-stage inflator for an inflatable vehicle airbag that includes a second-stage combustion cup having a variable gas generant capacity.

Background Art

[0002] This section provides background art information related to the present disclosure, and the background art information is not necessarily prior art.

[0003] Inflatable occupant restraints or airbags are commonly included in motor vehicles to provide impact protection for the vehicle occupants. When an accident occurs, one or more sensors within the vehicle measure, for example, an abnormal deceleration and trigger the inflation of the airbag within milliseconds by gas generated by a device commonly referred to as an "inflator". The inflated airbag protects the vehicle occupants from the impact force.

[0004] Various types of inflators for inflating airbags have been disclosed in the art. One known inflator device is shown and described in U.S. Patent No. 6,189,927 by the same applicant. The inflator of the '927 patent is an adaptive pyrotechnic inflator or two-stage inflator having gas generant material in two chambers. The gas generant material is actuated independently by two ignition devices. The gas generant material containment chambers of such an inflator may be referred to as "combustion chambers" because the gas generant material therein is burned or reacted to produce the gas used to inflate the associated occupant restraint. U.S. Patent No. 6,189,927 is incorporated herein by reference as if fully set forth herein.

[0005] Another known two-stage inflation device is shown and described in U.S. Patent Application No. 17 / 189,336 by the same applicant. The inflator of this application includes a housing defining a first chamber. The first chamber contains a first gas-generating material. A combustion cup is disposed within the first chamber and defines an interior for containing an igniter material. A first igniter device extends into the interior of the combustion cup. The combustion cup and lid, disposed within the first chamber, cooperate to define a second chamber for containing a second gas-generating material. The combustion cup includes cup sidewalls and an open end. The lid is typically in a closed position relative to the cup sidewalls to close the open end of the combustion cup and is movable away from the cup sidewalls in response to an increase in pressure within the combustion cup to expel combustion gases from the combustion cup. A second igniter device extends into the combustion cup. The lid and at least one of the cup sidewalls include an axially elongated vent shape that gradually appears in response to the movement of the lid away from the cup sidewall. U.S. Patent No. 17 / 189,336 by the same applicant is incorporated herein by reference as if it were described herein in its entirety.

[0006] Known inflators for inflatable occupant restraints, including but not limited to U.S. Patent No. 6,189,927 and U.S. Patent No. 17 / 189,336 by the same applicant, have generally proven suitable for their intended use, but there is a need for continued improvement in the relevant art. [Overview of the project]

[0007] This section provides an overview of the disclosure and does not constitute a comprehensive disclosure of the entire scope or all functions of the disclosure.

[0008] The general objective of this instruction is to provide a two-stage inflator having a fixed first-stage performance and a variable second-stage performance that can be adjusted for a specific application.

[0009] In a particular embodiment, this teaching provides a second-stage combustion cup for a two-stage inflator of an inflatable vehicle safety device. The second-stage combustion cup comprises a first member and a second member. The first member and the second member are formed separately from each other and cooperate to define an interior for receiving the second-stage gas-generating material. The second member may contain an amount of second-stage gas-generating material that can be varied to adjust the performance of the inflator for a particular application.

[0010] In another specific embodiment, this teaching provides a two-stage inflator for an inflatable vehicle safety device. The two-stage inflator includes a housing and a first combustion cup and a second combustion cup disposed within the housing. The second combustion cup may be a second-stage combustion cup including a first member and a second member formed separately from the first member and coupled to the first member. The first and second members cooperate to define an interior for receiving the second-stage gas generating material.

[0011] In yet another specific embodiment, the teaching provides a method for assembling a two-stage inflator for an inflatable vehicle safety device, comprising a first cup and a second cup or combustion cup, wherein the first cup is an igniter cup for containing igniter material, and the second cup is a second-stage combustion cup for containing second-stage combustion material. The method includes inserting a first member of the second-stage combustion cup into the housing of the inflator and inserting the first-stage combustion cup into the housing. The method further includes inserting a second member of the second-stage combustion cup into the housing after the first member of the second-stage combustion cup and the first-stage combustion cup have been inserted into the housing. The method further includes coupling the second member to the first member while the first and second members are in the housing.

[0012] Further areas of availability will become apparent from the descriptions provided herein. The descriptions and specific examples in this summary are intended for illustrative purposes only and are not intended to limit the scope of this disclosure. [Brief explanation of the drawing]

[0013] The drawings described herein are for illustrative purposes only of selected embodiments and not of all possible implementations, and are not intended to limit the scope of this disclosure. [Figure 1] Figure 1 is a cross-sectional view of the inflator for the inflatable vehicle safety device according to this instruction, showing the inflator in its pre-operation state. [Figure 2] Figure 2 is another cross-sectional view of the inflator shown in Figure 1, and the inflator is shown without the igniter material and gas generating material for illustrative purposes. [Figure 3] Figure 3 is an exploded perspective view of the inflator shown in Figure 1. [Modes for carrying out the invention]

[0014] Herein, one or more exemplary embodiments are described more fully with reference to the accompanying drawings. One or more exemplary embodiments are provided so as to fully convey the scope of the disclosure to those skilled in the art. Many specific details, such as examples of specific components, apparatus and methods, are described in order to give a full understanding of the embodiments of the disclosure. It will be obvious to those skilled in the art that specific details do not need to be adopted and that exemplary embodiments should not be construed as limiting the scope of the disclosure. Well-known processes, well-known apparatus structures and well-known techniques are not described in detail herein.

[0015] The terms “connected,” “joined,” and “communicated” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interactions. Two components may be joined to one another even if they are not in direct contact with each other. The term “adjacent” refers to things being physically close to each other, but not necessarily in direct contact. As used herein, “exemplary” means serving as a typical or representative example or case, and does not necessarily mean special or preferred.

[0016] By general reference to the drawings, a two-stage inflator for inflatable occupant protection devices such as inflatable airbags, as described in this instruction, is illustrated and generally identified by reference numeral 10. The inflator 10 shown in the drawings is a two-stage inflator adapted in particular to a passenger-side front airbag. However, it will be understood that various embodiments of this instruction can be readily adapted for use with driver-side front airbags and other airbags.

[0017] The inflator 10 has a cylindrical outer shape and is schematically illustrated to include a housing 12 formed from two structural components, namely a first housing portion or base portion 14 and a second housing portion or diffuser cap portion 16. Thus, the housing 12 may have a generally circular cross-section. The first housing portion 14 and the second housing portion 16 may be formed from steel, aluminum or other suitable material and may be fixed to each other, for example, by inertia welding, or otherwise suitably connected to each other. In the particular embodiment shown, the housing 12 may have a diameter of about 65.8 mm and a length L of about 68 mm. However, it will be understood that these dimensions are illustrative and can be readily adapted within the scope of this teaching.

[0018] As shown in the drawings, the second housing portion 16 may be considered as the upper housing portion, and the first housing portion 14 may be considered as the lower housing portion. These descriptive terms (e.g., upper and lower), as well as any other directional descriptive terms used with respect to housing portions 14 and 16, and elsewhere in this specification with respect to other features or elements, are understood to be merely to facilitate reference to the drawings and not to be limited. The second housing portion 16 as a whole is inverted bowl shape and includes an end wall 20 and a cylindrical side wall 22. The side wall 22 includes a plurality of spaced-apart gas outlet ports 24.

[0019] The first housing portion 14 includes a first mounting opening and a second mounting opening, respectively, indicated by reference numerals 26 and 28, the use of which will be discussed in more detail below. The first housing portion 14 can be integrally formed to include a peripheral mounting bracket 32 ​​extending radially outward from the housing 12.

[0020] The housing 12 is configured to define an interior or chamber 34. The interior 34 of the housing 12 may be generally cylindrical. The chamber 34 typically contains or houses a feed of a first gas generating material or first-stage gas generating material 36, in the form of an explosive, such as that known to be used in airbag inflators. Surrounding the first gas generating material 36 is a filter 40. The filter 40 may be formed from multiple layers or wraps of metal screen. Surrounding the filter 40 and generally adjacent to the inner surface of the side wall 22 is an adhesive-backed foil seal 42. The adhesive-backed foil seal 42 seals the gas generating material 36 inside the inflator 10, thereby protecting the gas generating material 36 from ambient conditions such as moisture.

[0021] The inflator 10 includes a first cup and a second cup or combustion cup 44 and 46 disposed within the interior 34 of the housing 12. The first cup may be an igniter cup or igniter tube 44, and the second cup may be a second-stage combustion cup 46. The first combustion cup 44 may include a cylindrical side wall 48. Ignition material 50 is housed within the first cup 44. A first-stage igniter device, i.e., a first igniter 52, is mounted to the housing 12 via a first mounting opening 26 and extends into the first cup 44. A second-stage igniter device, or second igniter 54, is mounted to the housing 12 via a second mounting opening 28 and extends into the second-stage combustion cup 46. As far as this teaching is concerned, it will be understood that the first igniter device 52 and the second igniter device 54 may take the form of known pyrotechnic initiator devices. Therefore, the first igniter device 52 and the second igniter device 54 may include a squib 56, a squib adapter or holder 58, and a squib seal 60. The igniter devices 52 and 54 are conventionally attached to the housing 12 by the squib adapter or holder 58, or fitted to the housing 12. The squib seal 60 conventionally seals the squib 56 together with the adapter 58.

[0022] The first cup 44 can be formed of a gas-impermeable material such as metal, and its cylindrical sidewall 48 includes a plurality of spaced, preferably substantially uniformly spaced, gas outlet orifices 62. The gas outlet orifices 62 may normally be covered (for example, when the inflator 10 is stationary or in a pre-operation state), and the passage of material may be prevented by a pressure-sensitive cover or barrier, for example, by an adhesive-backed foil seal wrap, as is well known in the art. As is known, the cover may be selected to open or burst when a predetermined pressure is applied from inside the first cup 44.

[0023] When actuated, ignition of the igniter material 50 causes the pressure inside the first cup 44 to increase, and upon subsequent predetermined rupture or opening of the cover, enables the ignition products generated by the combustion of the igniter material 50 to pass through the outlet orifice 62 from the first igniter device 52 to the gas generant material 36 housed inside the housing 12. Contact between the ignition products and the first gas generant material 36, or that which occurs therebetween, results in ignition and reaction of the first gas generant material 36. The generated expanding gas passes through the filter 40, ruptures the foil seal 42, passes through the gas outlet port 24 (as shown by arrow A in FIG. 2), exits the inflator 10 and enters the associated airbag cushion (not shown).

[0024] The second stage combustion cup 46, in the illustrated embodiment, is shown as being composed of a plurality of separate parts or members that cooperate to define an interior 64 having an interior volume for storing the second gas generant material 66. The second gas generant material 66 may be in the form of a pyrotechnic material and may be either the same or different in composition, shape, size or form compared to the first gas generant material 36. As shown in the drawings, the second stage combustion cup 46 may be formed separately and may include a first or lower member 68 and a second or upper member 70 that cooperate to define an interior 64 for receiving the second gas generant material 66. The first member 68 and the second member 70 may be press fit together or otherwise fixed to each other in any manner well known in the art. Alternatively, the second stage combustion cup 46 may include more than two members within the scope of the present teachings. As will be more fully understood hereinafter, the amount of the second stage gas generant material within the second stage combustion cup 46 can be varied to adjust the performance of the inflator 10.

[0025] The first member 68 of the combustion cup 46 of the second stage can be formed of a gas-impermeable material such as metal so as to include a side wall 72, a first axial end 74, and a second axial end 76. The first axial end is an open end 74 that is closed by the second igniter device 54. In the illustrated embodiment, the cup side wall 72 is a cylindrical side wall 72. The first member 68 includes a first diameter D1.

[0026] The second member 70 of the combustion cup 46 of the second stage can similarly be formed of a gas-impermeable material such as metal so as to include a side wall 78, a first or lower axial end 80, and a second or upper axial end 82. The first axial end 80 and the second axial end 82 are open ends. In the illustrated embodiment, the side wall 78 includes a first cylindrical portion 84 adjacent to the first axial end 80 and a second cylindrical portion 86 adjacent to the second axial end 82. The first cylindrical portion and the second cylindrical portion are a first axially extending portion 84 and a second axially extending portion 86, respectively. The first cylindrical portion 84 of the second member 70 defines a male portion that is received within the open upper end 76 of the first member 68. In this regard, the first member 68 defines a female portion. The first cylindrical portion 84 has an outer diameter that is nominally smaller than the first diameter D1 of the first member 68 such that the first cylindrical portion 84 can be press-fitted into the first member 68. In other embodiments, the first member 68 may define a male portion and the first cylindrical portion 84 may define a female portion. Further, one of the first member 68 and the second member 70 defines a male portion and the other of the first member 68 and the second member 70 defines a portion that receives the male portion.

[0027] The second cylindrical portion 86 of the second member 70 has a second inner diameter D2. The second inner diameter D2 is larger than the first inner diameter D1. The second member 70 further includes a radially extending flange 88 between the first axially extending portion 84 and the second axially extending portion 86.

[0028] The second cylindrical portion 86 of the side wall 78 of the second member 70 may include a plurality of spaced-apart, preferably substantially uniformly spaced, gas outlet orifices 90. The gas outlet orifices 90 may normally (for example, when the inflator is stationary or in a pre-operation state) be covered by a lid 92 that closes the second end of the second member 70 and extends axially over the portion of the second cylindrical portion 86 containing the gas outlet orifices 90.

[0029] When activated, the combustion of the gas generating agent material 66 in the second combustion cup 46 results in an increase in pressure inside the second stage combustion cup 46. The increase in pressure inside the second igniter 46 displaces the lid 92 away from the second member 70, exposing the gas outlet orifice 90. Again, the generated expanding gas passes through the filter 40 and the gas outlet port 24 (as indicated by arrow A in Figure 2) and exits the inflator 10 into the associated airbag cushion (not shown).

[0030] Continuing with reference to the drawings, the method of this instruction for assembling a two-stage inflator is described here. Assembly can be started by inserting the squib adapter 58 into the housing 12 and welding the adapter 58 to the housing 12. The squib 56 and filter 40 can then be inserted into the housing 12. Before inserting the second-stage combustion cup 46, the first-stage combustion cup or igniter tube 44 is inserted into the housing 12 and loaded with igniter material 50. Next, the first member 68 of the second-stage combustion cup 46 is inserted. In the next assembly step, the first gas generating material 66 is loaded into the housing and the first-stage damper pad 94 may be inserted. The second member 70 of the second-stage combustion cup 46 can then be inserted into the first member 68 and press-fitted in the manner considered above. As shown in the figure, the second member 70 of the second stage combustion cup 46 extends radially over the open upper end of the first stage combustion cup and covers the open upper end. Next, the second gas generating material 66 is loaded into the second stage combustion cup 46. The amount of the second gas generating material can be varied according to the desired performance of the inflator 10. The second stage damper pad 96 is inserted and the lid 92 is press-fitted onto the second member 70. The diffuser 16 of the housing 12 is positioned in place and inertia-welded to the base 14. The two-member configuration of the second stage combustion cup 46 in this teaching favorably allows for the loading of the first stage generating material before the loading of the second stage generating material. The enlarged volumetric area of ​​the second member 70 of the second stage combustion cup 46 covers the top of the sealed and independent first generating material load.

[0031] It will be understood that the inflator 10 according to this instruction can provide adjustable performance according to selected operating conditions required or desired for the installation and application of a particular inflatable restraint system. During operation, both the amount or rate of expansion gas generation can be appropriately modified, such as in the case of a vehicle collision or collision accident, to take into account one or more states of occupant presence. The result of such inflator performance adaptability is provided by two separate, ballistically isolated chambers of the gas generating agent material of the inflator 10 according to this instruction.

[0032] For example, such an inflator 10 can be operated to have a first stage opening in which the igniter material 50 is ignited to produce combustion products, which are then sent to the chamber 34 to burn the first gas generating material 36. In this way, the expanding gas can be generated at a first power level without activating or igniting the second igniter device 54 to activate the gas generating material 66 contained in the second stage combustion cup 44. As understood, such operation may be desirable to provide minimized or reduced inflator power, for example, in the case of a low-speed impact. Alternatively, the inflator 10 according to this teaching may be operated so that both the first igniter device 52 and the second igniter device 54 are activated.

[0033] As can be understood, the operation and ignition of both the first igniter device 52 and the second igniter device 54, and the first gas generating material 36 and the second gas generating material 66, may be accompanied by simultaneous or near-simultaneous operation and ignition of the first igniter device 52 and the second igniter device 54. Such simultaneous or near-simultaneous operation may be desirable to provide rapid inflation and deployment of the associated airbag cushion. For example, this rapid inflation and deployment may be desirable in response to a high-speed or severe vehicle collision. Alternatively, in response to the detection of a moderate vehicle collision, it may be desirable to sequentially operate and ignite the first igniter device 52 and the second igniter device 54. Furthermore, such sequential operation and ignition may allow the time lag or delay between the operation and ignition of the first and second squibs, and consequently the combustion of the first gas generating material 36 and the second gas generating material 66, to be adjusted to meet specific requirements for the installation of a particular inflatable restraint system, as can be understood by those skilled in the art. Therefore, such inflator assemblies are particularly well-suited for use as adaptive power inflators, in that they can be manufactured to depend largely on one or more selected operating conditions, such as ambient temperature, the presence of occupants, the use of seat belts, and the vehicle's deceleration rate.

[0034] While specific embodiments and uses of the Disclosure are illustrated and described, it will be understood that the present invention is not limited to the exact configurations and components disclosed herein. Various modifications, changes, and variations that will be apparent to those skilled in the art may be made in the arrangement, operation, and details of the methods and systems disclosed herein without departing from the spirit and scope of the Disclosure.

Claims

1. A second stage combustion cup 46 for a two-stage inflator 10 of an inflatable vehicle safety device, The first member 68 and The second member 70 comprises, A second-stage combustion cup 46 characterized in that the second member 70 is formed separately from the first member 68 and is coupled to the first member 68, the first member 68 and the second member 70 cooperate to define a continuous interior 64 for receiving the second-stage gas generating agent material, and the second member is selectable from a plurality of volumes to change the second-stage gas generating agent capacity of the second-stage combustion cup.

2. The second stage combustion cup 46 according to claim 1, characterized in that the first member 68 includes a first axial end 74 for receiving a second stage igniter device 54 and a second axial end 76 on the opposite side, the second axial end 76 being an open end, and the second member 70 includes an open connecting portion 80 for receiving the second axial end 76 of the first member 68, and as a result, the first member 68 and the second member 70 cooperate to define a continuous combustion chamber.

3. The second stage combustion cup 46 according to claim 2, further characterized by a second stage lid 92 that closes the open side of the second stage combustion cup 46, wherein the second stage lid 92 is attached to the first member 68 and is spaced axially apart from the open connection portion of the second member 70.

4. The second stage combustion cup 46 according to any one of claims 1 to 3, characterized in that the first member 68 and the second member 70 of the second stage combustion cup 46 are press-fitted with each other.

5. The second stage combustion cup 46 according to claim 2 or 3, characterized in that the second member 70 includes a first axially extending portion 84 and a second axially extending portion 86, wherein the first axially extending portion 84 has a first inner diameter, and the second axially extending portion 86 has a second inner diameter, the second inner diameter being larger than the first inner diameter.

6. The second stage combustion cup 46 according to claim 2 or 3, wherein the second member 70 includes a first axially extending portion 84, a second axially extending portion 86, and a radially extending flange 88 between the first axially extending portion 84 and the second axially extending portion 86, the first axially extending portion 84 having a first inner diameter, and the second axially extending portion 86 having a second inner diameter, the second inner diameter being larger than the first inner diameter.

7. The second stage combustion cup 46 according to claim 6, characterized in that the first axially extending portion 84 extends within the first member 68.

8. The second stage combustion cup 46 according to any one of claims 1 to 3, characterized in that the first member 68 and the second member 70 are cylindrical.

9. A second-stage combustion cup 46 according to any one of claims 1 to 3, characterized in that it is combined with the two-stage inflator 10.

10. The aforementioned two-stage inflator 10 further includes a first-stage combustion cup, The second stage combustion cup 46 according to claim 5, combined with the two-stage inflator 10, characterized in that the second axially extending portion 86 of the second member 70 extends radially over the first stage combustion cup.

11. The two-stage inflator 10 further includes a first-stage combustion cup, The second stage combustion cup 46 according to claim 6, combined with the two-stage inflator 10, characterized in that the second axially extending portion 86 of the second member 70 extends radially over the first stage combustion cup.

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