Two-stage inflator

Abstract

The present disclosure provides a dual stage inflator (10) for an inflatable vehicle safety device, the dual stage inflator including a housing (12) defining a first chamber (34) containing a first gas generating material (36). An igniter cup (46) is disposed in the first chamber (34) and defines an interior containing an igniter material (49). A first igniter device (50) extends into the interior of the igniter cup. A combustion cup (62) and a cover (64) are disposed in the first chamber and cooperate to define a second chamber (66) containing a second gas generating material (68). The combustion cup includes a cup sidewall (69) extending between a first axial end (70) and a second axial end (72). The first axial end is an open end. The cover is normally in a closed position relative to the combustion cup to close the open end of the combustion cup and is movable away from the combustion cup in response to an increase in pressure within the combustion cup to vent combustion gases out of the combustion cup. A second igniter device (84) extends into the combustion cup and closes the second axial end (72) of the combustion cup. The combustion cup includes a first axially extending portion (74) adjacent the first axial end having a first outer diameter and a second axially extending portion (76) adjacent the second axial end having a second outer diameter greater than the first outer diameter. The cover includes a cover sidewall (62) extending in the axial direction and radially overlapping at least a portion of the combustion cup including the first outer diameter.

Description

Technical Field

[0001] This disclosure generally relates to an inflator for supplying inflation gas to inflatable vehicle safety devices, such as inflatable airbags. More specifically, the invention relates to a two-stage inflator for inflatable vehicle airbags. Background Technology

[0002] This section provides background information relating to this disclosure, which is not necessarily prior art.

[0003] Motor vehicles typically include inflatable occupant restraint devices, or airbags, to provide impact protection for vehicle occupants. In the event of an accident, one or more sensors inside the vehicle measure, for example, abnormal deceleration, and within milliseconds, trigger the airbag to inflate using gas produced by a device commonly known as an "inflator." The inflated airbag cushions the impact force on the vehicle occupants and protects them from injury.

[0004] Various types of inflators for airbag inflation have been disclosed in the prior art. A known inflator device is shown and described in commonly assigned U.S. Patent No. 6,189,927 ('927 Patent). The inflator of the '927 Patent is an adaptive pyrotechnic inflator or a two-stage inflator having gas-generating material in two chambers. The gas-generating material is independently activated by two ignition devices. The chamber containing the gas-generating material in such an igniter may be referred to as a "combustion chamber" because the gas-generating material therein is burned or otherwise reacted to produce gas for inflating the associated occupant restraint devices. U.S. Patent No. 6,189,927 is hereby incorporated by reference, as if fully set forth herein.

[0005] While known inflators for inflatable occupant restraint devices (including the inflator of U.S. Patent No. 6,189,927) have generally proven suitable for their intended use, continuous improvement is still needed in the related art. Summary of the Invention

[0006] This section provides a general overview of this disclosure and is not a full disclosure of its entire scope or all its features.

[0007] The general objective of this teaching is to provide a two-stage inflator with a combustion cup that includes a lid and has an increased volume for loading a gas generator.

[0008] According to one embodiment, this teaching provides a two-stage inflator for an inflatable vehicle safety device, the two-stage inflator including a housing defining a first chamber containing a first gas-generating material. An igniter cup is disposed in the first chamber and defines an interior containing igniter material. A first igniter device extends into the interior of the igniter cup. A combustion cup and a cap are disposed in the first chamber and cooperate to define a second chamber containing a second gas-generating material. The combustion cup includes a cup sidewall extending between a first axial end and a second axial end. The first axial end is an open end. The cap is normally in a closed position relative to the combustion cup to close the open end of the combustion cup and can move away from the combustion cup 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 and closes the second axial end of the combustion cup. The combustion cup includes a first axial extension having a first outer diameter adjacent to the first axial end and a second axial extension having a second outer diameter greater than the first outer diameter adjacent to the second axial end. The lid includes a lid sidewall that extends in an axial direction and radially overlaps with at least a portion of the combustion cup portion, including a first outer diameter.

[0009] According to another specific embodiment, this teaching provides an inflator for an inflatable vehicle safety device, the inflator including a cup portion having cup sidewalls and an open end. The cup sidewalls extend between a first axial end and a second axial end. A cap cooperates with the cup sidewalls to define a combustion chamber. The cap generally closes the combustion chamber and is movable away from the cup sidewalls to expel combustion gases from the combustion chamber. A gas generating agent is disposed within the combustion chamber. An ignition device extends into the combustion chamber. The cup portion includes a first axially extending portion having a first outer diameter adjacent to the first axial end and a second axially extending portion having a larger second outer diameter adjacent to the second axial end. The cap includes an axially extending cap sidewall that extends in the axial direction and radially overlaps with at least a portion of the cup portion including the first outer diameter.

[0010] Other applicable fields will become apparent from the description provided herein. The descriptions and specific examples in this invention are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0011] The accompanying drawings described herein are for illustrative purposes only for selected embodiments and not all possible implementations, and are not intended to limit the scope of this disclosure.

[0012] Figure 1 This is a cross-sectional view of an inflator for an inflatable vehicle safety device, as per the teachings of this invention, showing the inflator before activation.

[0013] Figure 2 yes Figure 1Another cross-sectional view of the inflator, which is shown for illustrative purposes as having no igniter material and no gas generating material.

[0014] Figure 3 It is along Figure 1 The sectional view taken from line 3-3 of A.

[0015] Figure 3A yes Figure 3 A magnified portion of the sectional view.

[0016] Figure 4 yes Figure 1 A perspective view of the second stage cover of the inflator.

[0017] Figure 5 It is used for Figure 1 A perspective view of the alternative second-stage cover of the inflator.

[0018] Figure 6 It is a pressure curve of the combustion chamber relative to time, including the second-stage air-filling device. Detailed Implementation

[0019] One or more exemplary embodiments will now be described more fully with reference to the accompanying drawings. One or more exemplary embodiments are provided so that this disclosure will be thorough and will fully communicate the scope to those skilled in the art. Numerous specific details, such as examples of specific components, apparatuses, and methods, are set forth to provide a thorough understanding of embodiments of this disclosure. It will be apparent to those skilled in the art that specific details are not required, and the exemplary embodiments should not be construed as limiting the scope of this disclosure. Well-known processes, well-known apparatus structures, and well-known techniques are not described in detail herein.

[0020] The phrases “connected to,” “linked to,” and “connected to” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interactions. Two components may be connected to each other even if they are not in direct contact. The term “adjacent” refers to items that are physically very close to each other, although these items are not necessarily in direct contact. As used herein, “exemplary” means an example or instance used as typical or representative, and does not necessarily refer to a particular or preferred one.

[0021] Referring generally to the accompanying drawings, a two-stage inflator for inflatable occupant protection devices (such as airbags) according to the present teachings is shown, and this two-stage inflator is generally indicated by reference numeral 10. The inflator 10 shown in the drawings is a two-stage inflator particularly suitable for passenger-side front airbags. However, it should be understood that various aspects of the present teachings can be readily adapted for use with driver-side front airbags and other airbags.

[0022] The inflator 10 is generally shown with a cylindrical outer profile and includes a housing 12 formed by two structural components: a first housing portion or base portion 14 and a second housing portion or diffuser cover 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 of aluminum or other suitable materials and may be secured to each other by, for example, inertial welding and welding, or otherwise suitably connected to each other. In the particular embodiment shown, the housing 12 may have a diameter of approximately 65.8 mm and a length L of approximately 68 mm.

[0023] As shown in the accompanying drawings, the second housing portion 16 can be considered the upper housing portion, and the first housing portion 16 can be considered the lower housing portion. These descriptors (e.g., upper and lower) used with respect to housing portions 14 and 16, and elsewhere herein, for other features or elements, are to be understood as merely for convenience of reference to the drawings and are not to be construed as limiting. The second housing portion 16 is generally inverted bowl-shaped and includes an end wall 20 and cylindrical sidewalls 22. The sidewalls 22 include a plurality of spaced-apart gas outlets 24.

[0024] The first housing portion 14 includes a first mounting opening and a second mounting opening, indicated by reference numerals 26 and 28, respectively, the use of which will be discussed in more detail below. The first housing portion 14 may be integrally formed to include an outer peripheral mounting bracket 32 ​​extending radially outward from the housing 12.

[0025] The housing 12 is configured to define a first chamber 34. The first chamber 34 may be generally cylindrical. The first chamber 34 contains or contains a quantity of a first gas-generating material 36, which is typically a pyrotechnic gas-generating material, such as gas-generating materials known for use in airbag inflators. A filter 40 surrounds the first gas-generating material 36. The filter 40 may be formed of multiple layers or multiple turns of metal mesh. An adhesive foil seal 42 surrounds the filter 40 and is generally adjacent to the inner surface of the sidewall 22. The adhesive foil seal 42 can hermetically seal the gas-generating material 36 within the inflator 10, thereby protecting the gas-generating material from environmental conditions (e.g., moisture). The inflator 10 may also include a retainer 44 to hold the inflator components in a suitably opposing arrangement within the inflator 10.

[0026] Igniter cup 46 is disposed within the first chamber 34. As shown, the first igniter cup 46 defines an ignition chamber 47 and may include cylindrical sidewalls 48. Igniter material 49 is contained within the igniter cup 46. The first igniter device 50 is mounted to the housing 12 via a first mounting opening 26 within the first chamber 34. For the purposes of this teaching, it should be understood that the first igniter device 50 may take the form of a known pyrotechnic device. Thus, the first igniter device 50 may include an ignition tube 52, an ignition tube adapter or retainer 54, thereby including an ignition tube seal 56. The igniter device 50 is typically mounted to or mates with the housing 12 via the ignition tube adapter or retainer 54. The ignition tube seal 56 typically seals the ignition tube 52 using the adapter 54.

[0027] As shown, the igniter cup 46 may include an open upper end closed by a spacer member 58. The spacer member 58 may be generally cylindrical in shape with a closed lower end. The spacer member or igniter tube cap 58 may be used to prevent the igniter generator propellant 49 from dislodging from the igniter cup 46. The spacer member 58 has holes at its bottom that allow gases produced by combustion to ignite the propellant. Alternatively, the igniter cup 46 may be integrally formed to include a closed upper end.

[0028] The igniter cup 46 may be formed of an impermeable material (such as metal), and the cylindrical sidewall 48 includes a plurality of spaced-apart, preferably substantially uniformly spaced, gas outlet holes 60. The gas outlet holes 60 may typically be covered (e.g., when the inflator is stationary or before startup) and prevented from passing through by a pressure-sensitive cover or barrier (such as a sealed package with adhesive foil, as is known in the art). It is understood that the cover may be selected to open or rupture when a predetermined pressure is applied from the interior of the igniter cup 46.

[0029] Upon activation, the ignition of the igniter material 49 causes an increase in pressure inside the igniter cup 46, subsequently causing the cover to rupture or open as intended, allowing the ignition products generated by the combustion of the igniter material 49 to pass through the outlet port 60 from the first igniter device 50 to the gas generating material 36 contained in the first chamber 34. The resulting contact between the ignition products and the first gas generating material 36 leads to the ignition and reaction of the first gas generating material 36. The generated charging gas passes through the filter 40, causing the foil seal 42 to rupture, and passes through the gas outlet 24 (e.g., Figure 3 (As indicated by arrow A in the diagram), and exits the inflator 10 into the associated airbag cushion (not shown).

[0030] The first chamber 34 also houses or includes a combustion cup portion 62 or a second-stage cup portion and a lid 64. The combustion cup portion 62 and the lid 64 cooperate to define a secondary chamber or a second chamber or a combustion chamber 66. The second chamber contains a second gas generating material 68. The second gas generating material 68 may be in the form of pyrotechnic material and may be the same as or different from the first gas generating material 36 in composition, shape, size, or form.

[0031] The combustion cup portion 62 includes a cup sidewall 69, a first axial end 70, and a second axial end 72. The first axial end is an open end 70. In the illustrated embodiment, the cup sidewall is a cylindrical sidewall 69. The cap 64 is normally in a closed position relative to the cup sidewall 69 to close the open end 70 of the combustion cup portion 62. As will be discussed further below, the cap 64 can move axially away from the cup sidewall 69 in response to an increase in pressure within the combustion cup portion 62 to expel combustion gases from the combustion cup portion 62. The axial direction will be understood as the up-down direction, as shown in the figures. Like the igniter cup portion 46, the combustion cup portion 62 may be formed of an impermeable material, such as metal.

[0032] In the illustrated embodiment, the combustion cup portion 62 is shown as including a first axially extending portion 74 adjacent to the first end 70 and a second axially extending portion 76 adjacent to the second end 72. The first axially extending portion 74 has a first outer diameter D1, and the second axially extending portion 76 has a second outer diameter D2. The first outer diameter D1 is smaller than the second outer diameter D2. The cup portion sidewall 64 includes a tapered portion 78 between the first axially extending portion 74 and the second axially extending portion 76. The tapered portion 78 gradually tapers from the first outer diameter D1 to the second outer diameter D2. In the specific embodiment shown, the first outer diameter D1 is approximately 27.8 mm, and the second outer diameter D2 is approximately 31 mm.

[0033] The cap 64 includes an end portion 80 and a cap sidewall 82. The cap sidewall 82 extends in an axial direction and radially overlaps at least a portion of the first axial portion 74 of the combustion cup portion 62. The cap sidewall 82 has a third outer diameter D3. In some applications, the third outer diameter D3 is not greater than the first outer diameter D1. In the illustrated embodiment, the third outer diameter D3 is substantially equal to the first outer diameter D1. The cap sidewall 82 has a wall thickness. The second axially extending portion 76 of the combustion cup portion 62 can be positioned closer to the filter 40 than the thickness of the cap sidewall 82. In this way, the volume within the combustion cup portion 62 can be effectively increased to accommodate a larger amount of the second gas generating material 68. In the illustrated embodiment, the volume of the combustion chamber 66 is jointly defined by the combustion cup portion 62 and the cap 64.

[0034] The second end 72 of the combustion cup portion 62 is closed by the second igniter device 84. In the illustrated embodiment, the combustion cup portion 62 is shown as including an axially extending circumferential flange 86 at the second end 72. An end wall 87 extends radially between the axially extending circumferential flange 86 and the second portion 76 of the combustion cup portion 62. The axially extending circumferential flange 86 defines an opening 88 for receiving the second igniter device 84. The opening 88 has a fourth diameter D4 smaller than a first diameter D1. The axially extending circumferential flange 86 is shown extending away from the second portion 76 of the combustion cup portion 62. Alternatively, the axially extending circumferential flange 86 may extend into the second portion 76 of the combustion cup portion 62. The second igniter device 84 is mounted to or mates with the housing 12 via a second ignition tube adapter or retainer 90. The second ignition tube seal 92 seals the second ignition tube 84 using the adapter 90.

[0035] At least one of the lid 64 and the cup sidewall 69 includes an exhaust geometry for discharging combustion gases from the combustion cup portion 62. According to this teaching, at least one of the lid 64 and the cup sidewall 69 may include an axially elongated exhaust geometry that gradually emerges in response to movement of the lid 64 away from the cup sidewall 69. The axially elongated exhaust geometry may be in the form of at least one axially elongated hole 94, at least two axially spaced holes 96, or a combination thereof. In the illustrated embodiment, the axially elongated exhaust geometry is disposed in the lid sidewall 82.

[0036] Special reference Figure 3 and Figure 3 C and Figure 4 A cross-sectional view shows the cover 64 as including a plurality of axially elongated holes 94. In the illustrated embodiment, the cover 64 includes six axially elongated holes 94 spaced equidistantly around the cover sidewall 82. In this particular embodiment, the axially elongated holes 94 may be similarly shaped. It should be understood that, within the scope of this teaching, the cover 64 may include more or fewer axially elongated holes 94. It should also be understood that the holes 94 may have different shapes or different sizes.

[0037] Turn Figure 5 An alternative cover 98 according to the teachings is shown. Unlike cover 64, cover 98 includes an elongated venting geometry in the form of a plurality of axially spaced holes 96. As shown, the holes 96 are circular. Alternatively, the holes 96 can be elongated or any other shape. The holes 96 can be arranged in circumferentially extending rows. As shown, the sidewall 82 of cover 98 includes three rows of holes. The circumferentially extending rows of holes can be axially spaced from each other.

[0038] It should be understood that the inflator 10 according to this teaching can provide operational performance according to selected operating conditions required or desired by a particular inflatable restraint system device and application. More specifically, the inflator 10 of this teaching can be activated in such a way that one or both of the amount or rate of inflation gas produced can be appropriately altered, such as in the event of a vehicle collision or crash, to take into account the presence of one or more occupants. Such inflator performance adaptability results are provided by two separate and ballistically isolated gas-generating material chambers of the inflator 10 of this teaching.

[0039] For example, such an inflator 10 can be operated to have a first-stage emission, wherein igniter material 49 is ignited to produce combustion products, which are conveyed to a first chamber 34 to burn a first gas-generating material 36. In this way, inflation gas can be generated at a first output level without activating or igniting the second igniter device 84, or reacting with or not activating the gas-generating material 68 contained in the second chamber 66. As will be understood, such operation may be desirable to provide a minimized or reduced inflator output, such as in the case of a low-speed collision. Alternatively, an inflator 10 according to the present teachings can be operated such that both the first igniter device 50 and the second igniter device 84 are activated.

[0040] As will be understood, such operation and ignition of the first ignition device 50 and the second ignition device 84, as well as the first gas generating material 36 and the second gas generating material 68, may include simultaneous or near-simultaneous activation and ignition of the first ignition device 50 and the second ignition device 84. Such simultaneous or near-simultaneous activation 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, sequential activation and ignition of the first ignition device 50 and the second ignition device 84 may be desirable in response to the detection of a moderately severe vehicle collision. Furthermore, as those skilled in the art will understand, through such sequential activation and ignition, the time lag or delay between the activation and ignition of the first and second ignition tubes, and consequently the combustion of the first gas generating material 36 and the second gas generating material 68, can be adjusted to meet the specific requirements of a particular inflatable restraint system device. Therefore, such inflator components are particularly well-suited for applications as adaptive output inflators, as they can typically be manufactured to meet one or more selected operating conditions, such as ambient temperature, occupant presence, seatbelt use, and the vehicle's deceleration rate.

[0041] As the second igniter device 84 is activated, the second gas generating material 68 is burned to produce reaction products, causing an increase in pressure within the cup 66. This increase in pressure causes the lid 64 to shift away from the combustion cup 62, gradually revealing the elongated exhaust geometry in the lid's sidewall 82. Figure 6 As shown in the graph (pressure versus time within combustion chamber 66), the gradual exposure of the elongated exhaust geometry helps maintain the pressure within combustion chamber 66 for a longer period. As a result, the second gas generating material 68 can burn more completely, and associated effluent is reduced.

[0042] Therefore, this teaching provides a two-stage inflator 10 having a combustion cup portion 62 with a lid 80, which has an increased volume for loading the gas generating agent compared to a conventional combustion cup portion with a constant diameter. In the specific application described herein, the two-stage inflator 10 of this teaching can achieve a volume increase of at least 5%, preferably at least 10%, more preferably at least 15%. In one example, this teaching provides an increase of approximately 19.85% in volume.

[0043] While specific embodiments and applications of this disclosure have been shown and described, it should be understood that the invention is not limited to the precise constructions and components disclosed herein. Various modifications, alterations, and variations, which will be apparent to those skilled in the art, may be made to the arrangement, operation, and details of the methods and systems disclosed herein without departing from the spirit and scope of this disclosure.

Claims

1. A two-stage inflator (10) for an inflatable vehicle safety device, the two-stage inflator (10) comprising: The housing (12) defines a first chamber (34) containing a first gas generating material (36); Igniter cup (46), which is disposed in the first chamber (34) and defines an interior containing igniter material (49); A first igniter device (50) extends into the interior of the igniter cup (46); A combustion cup portion (62) and a lid (64) are disposed in the first chamber (34) and cooperate to define a second chamber (66) containing a second gas generating material (68). The combustion cup portion (62) includes a cup portion sidewall (69) extending between a first axial end (70) and a second axial end (72), the first axial end (70) being an open end. The lid (64) is normally in a closed position relative to the combustion cup portion (62) to close the open end (70) of the combustion cup portion (62). The lid (64) is capable of moving away from the combustion cup portion (62) in response to an increase in pressure within the combustion cup portion (62) to expel combustion gases from the combustion cup portion (62). A second igniter device (84) extends into the combustion cup portion (62) and closes the second axial end (72) of the combustion cup portion (62); and A filter (40) is located radially between the cup sidewall (69) and the housing (12); Its features are: The combustion cup portion (62) includes a first axial extension portion (74) with a first outer diameter adjacent to the first axial end (70) and a second axial extension portion (76) with a second outer diameter adjacent to the second axial end (72), wherein the first outer diameter is smaller than the second outer diameter. The lid (64) includes a lid sidewall (82) extending in the axial direction and radially overlapping at least a portion of the combustion cup portion (62), including a first outer diameter. The cover sidewall (82) has a thickness in the radial direction, and the second axial extension (76) of the combustion cup portion (62) is positioned closer to the filter (40) in the radial direction than the thickness of the cover sidewall (82).

2. The two-stage inflator (10) according to claim 1, characterized in that, The cup sidewall (69) includes a tapered portion (78) located between the first axial extension portion (74) and the second axial extension portion (76).

3. The two-stage inflator (10) according to any one of the preceding claims, characterized in that, The lid sidewall (82) includes an exhaust geometry for discharging combustion gases from the second chamber (66), the exhaust geometry being exposed in response to movement of the lid (64) away from the cup sidewall (69).

4. The two-stage inflator (10) according to claim 1 or 2, characterized in that, The cover sidewall (82) has a third outer diameter, which is not greater than the first outer diameter.

5. The two-stage inflator (10) according to claim 1 or 2, characterized in that, The cover sidewall (82) has a third outer diameter, which is substantially equal to the first outer diameter.

6. The two-stage inflator (10) according to claim 1 or 2, characterized in that, The combustion cup portion (62) further includes an axially extended circumferential flange (86) located at the second axial end (72), the axially extended circumferential flange (86) defining an opening for receiving the second igniter device (84), the opening defined by the axially extended circumferential flange (86) having a fourth diameter smaller than the first outer diameter.

7. The two-stage inflator (10) according to claim 6, characterized in that, The axially extending circumferential flange (86) extends away from the second axially extending portion (76) of the combustion cup portion (62).

8. The two-stage inflator according to claim 6, characterized in that, The combustion cup portion (62) further includes an end wall (87) extending radially between the axially extending circumferential flange (86) and the second axially extending portion (76).

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