Inflator for passive vehicle safety devices

Abstract

An inflator (10) for generating inflation gas for a safety device includes a housing (12) having an inner cavity comprising a combustion chamber (20) and a filter chamber (22). A filter (62) is disposed within the filter chamber (22). A separator (78) is disposed on a first axial side (72) of the filter (62) within the housing (12) and separates the filter chamber (22) from the combustion chamber (20). A heat insulation member (84) is disposed on a second axial side (76) of the filter (62) within the filter chamber (22). The second axial side (76) is opposite to the first axial side (72). The separator (78) is connected to the heat insulation member (84).

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Patent Application No. 17 / 130,111, filed December 22, 2020. The entire disclosure of the above application is incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to an inflator that provides inflation gas for passive vehicle safety devices, such as inflatable airbags. More specifically, this disclosure relates to an inflator for a passive vehicle safety device having a heat-insulating member on a first axial side of a filter, the heat-insulating member being coupled to a separating member on a second opposing axial side of the filter. Background Technology

[0004] This section provides background information relating to this disclosure, which is not necessarily prior art.

[0005] Inflatable occupant restraints, or airbags, are typically included in motor vehicles. In the event of an accident, sensors inside the vehicle measure, for example, abnormal deceleration, and within milliseconds, trigger the inflation of the airbag using gas produced by a device commonly known as an "inflator." The inflated airbag cushions the impact force on the vehicle occupants.

[0006] Inflators typically have one or more chambers containing gas-generating agent material. Adaptive pyrotechnic inflators contain gas-generating agent material in two chambers, which are independently activated by two ignition devices commonly referred to as "two-stage" inflators. In practice, each such gas-generating agent material containing chamber may be referred to as a "combustion chamber" because the gas-generating agent material therein is burned or otherwise reacted to produce gas for inflating the associated occupant restraints.

[0007] A known inflator is shown and described in commonly assigned U.S. Patent No. 7,950,693. The inflator is a two-stage inflator device comprising a housing defining a first chamber and a second chamber, each containing a quantity of a combustible gas-generating agent to produce an inflating gas. U.S. Patent No. 7,950,693 is incorporated herein by reference as if fully set forth herein.

[0008] While known inflators for inflatable occupant restraints (including the inflator of U.S. Patent No. 7,950,693) have generally proven suitable for their intended use, continuous improvement is still needed in the related art. Summary of the Invention

[0009] This section provides a general overview of this disclosure and is not a full disclosure of its entire scope or all its features.

[0010] According to one particular aspect, this teaching provides an inflator for generating inflation gas for a safety device. The inflator includes a housing having an inner cavity comprising a combustion chamber and a filter chamber. A filter is disposed within the filter chamber. A separating member is disposed within the housing on a first axial side of the filter and separates the filter chamber from the combustion chamber. A heat-insulating member is disposed within the filter chamber on a second axial side of the filter. The second axial side is opposite to the first axial side. The separating member is coupled to the heat-insulating member.

[0011] 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

[0012] 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.

[0013] Figure 1 This is a cross-sectional view of an inflator for inflatable occupant restraints, according to this teaching, showing the inflator before activation.

[0014] Figure 1A This teaching is similar to Figure 1 A cross-sectional view of the inflator, showing the inflator after it has been activated.

[0015] Figure 2 This is a perspective view of the cover of the second-stage igniter device according to this teaching.

[0016] Figure 3 It is along Figure 2 The cross-sectional view taken from line 3-3.

[0017] Figure 4 This is a simplified perspective view of the filter of the inflator used in this teaching.

[0018] Figure 5 yes Figure 4 A top view of the filter.

[0019] Figure 6 It is along Figure 5 The cross-sectional view taken from line 6-6.

[0020] Figure 7A This is a top view of the partition of the inflator of this teaching, showing the partition before the inflator is activated.

[0021] Figure 7B It is similar to Figure 7A The top view shows the partition components after the inflator has been activated.

[0022] Figure 8 This is a perspective view of the insulation component of the inflator of this teaching.

[0023] Figure 9 yes Figure 9 A bottom view of the thermal insulation component. Detailed Implementation

[0024] 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.

[0025] 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 do not necessarily have to be in direct contact. The phrase “fluidly connected” means that two features are connected such that fluid within one feature can enter the other. As used herein, “exemplary” refers to a typical or representative example or instance and does not necessarily refer to a particular or preferred one.

[0026] Referring to the accompanying drawings, an inflator for an inflatable occupant protection device according to the present teachings is shown, and the inflator is generally indicated by reference numeral 10. The inflator 10 is part of an occupant restraint system of a motor vehicle including an inflatable airbag (not specifically shown). The inflator 10 shown is a two-stage inflator particularly suitable for driver-side front airbags. However, it should be understood that various aspects of the present teachings can be readily adapted for use with passenger-side front airbags and other airbags.

[0027] The inflator 10 is generally shown as comprising a housing 12 having a first housing portion 14 and a second housing portion 16. In the illustrated embodiment, the housing 12 has a generally circular cross-section. The first housing portion 14 may be inertially welded or otherwise suitably attached to the second housing portion 16. The first housing portion 14 and the second housing portion 16 cooperate to define an inner cavity 20 having a filter chamber 22 separated from the combustion chamber 24 by an inner wall 26.

[0028] Combustion chamber 24 includes a first portion or first combustion chamber portion 28 that contains a first gas generating agent material 30. Combustion chamber 24 further includes a second portion or second combustion chamber portion 32 that contains a second gas generating agent material 34. For the purposes of this teaching, the first gas generating agent material 30 and the second gas generating agent material 34 may be the same material or may be different materials.

[0029] The inner wall may be an exhaust wall or a gas generator retaining wall 26 for retaining the first gas generator material 30 and the second gas generator material 34 within the combustion chamber 24. The gas generator retaining wall 26 includes a plurality of openings 36 for discharging combustion gases from the combustion chamber 24 to the filter chamber 22. A foam tray 38 may be disposed in the combustion chamber 24 adjacent to the gas generator retaining wall 26. As those skilled in the art will understand, the foam tray is generally used to provide stability for the storage of the first gas generator material 30 and the second gas generator material 34, which may settle within the combustion chamber 24 over time. The foam tray may be consumed during combustion of the first gas generator material 30 and the second gas generator material 34.

[0030] A first-stage ignition device 40 is disposed in the first portion 28 of the combustion chamber 24 for burning the first gas generating agent material 30. A second-stage ignition device 42 is correspondingly disposed in the second portion 32 of the combustion chamber 24 for burning the second gas generating agent material 34. For the purposes of this teaching, the first-stage ignition device 40 and the second-stage ignition device 42 are to be understood as conventional in construction and operation. The first-stage ignition device 40 and the second-stage ignition device 42 can be conventionally mounted to or cooperate with the housing 12.

[0031] The second portion 32 of the combustion chamber 24 is defined by one or more sidewalls 44 and a cover 46. In the illustrated embodiment, the one or more sidewalls comprise a single continuous wall or chamber wall 44. The wall 44 may be elliptical, circular, or any other cross-sectional shape. At a first end of the chamber wall 44 (the lower end shown in the figure), the chamber wall 44 receives a second-stage ignition device 42, and the base 48 of the second-stage ignition device 42 closes the first end. At a second end or opposite end of the chamber wall 44 (the upper end shown in the figure), the cover 46 normally (i.e., before the intake manifold 10 is activated) closes the second portion 32 of the combustion chamber 24. The cover 46 may be elliptical in shape or otherwise constructed in cooperation with the chamber wall 44 to close the second portion 32 of the combustion chamber 24.

[0032] The cover 46 can be moved axially from a first or closed position before combustion of the gas generating agent material to a second or open position after combustion of the gas generating agent material. Figure 1 The image shows the gas generator 10 before the combustion of gas generating materials 30 and 34. Figure 1 The image shows the inflator after the combustion of gas generating materials 30 and 34. Further explanation is given regarding the combustion of the second gas generating material 34 before combustion (e.g., ...). Figure 1 As shown in the cross-sectional view, the cover 46 is axially spaced from the generator retaining wall 26. As shown, the cover 46 can be spaced from the generator retaining wall 26 via the foam disc 38. During the combustion of the second gas generator material 34 (e.g....), Figure 1A As shown in the cross-sectional view, the foam disc 38 is consumed by the heat of the reaction, and the cover 46 is axially displaced (upward as shown) to a position adjacent to the initiator retaining wall 26 in response to the pressure increase within the second part 32 of the combustion chamber 24.

[0033] The outer side 50 of the cap 46 and the adjacent side 52 of the gas generator retaining wall 26 can be cooperatively configured to allow improved flow of combustion gases between the gas generator retaining wall 26 and the cap 46 when the cap is in the open position abutting against the gas generator retaining wall 26. In this respect, at least one of the outer side 50 of the cap and the adjacent side 52 of the gas generator retaining wall 26 includes a planar portion 54 and a raised portion 56. In the illustrated embodiment, the cap 46 includes a planar portion, a raised portion 56, and an adjacent side 52. The raised portion may be stamped into the cap 46 or otherwise formed together with or in the cap, and may extend outward from the planar portion 54 in a direction away from the second portion 32 of the combustion chamber 24.

[0034] The protruding portion 56 of the cover 46 is configured to cooperate with the gas generator holding wall 26 and maintain a generally parallel orientation between the gas generator holding wall 26 and the planar portion 54 of the cover 46 when the cover 46 is in the open position and abuts against the gas generator holding wall 26. For this purpose, the protruding portion 56 includes at least three spaced points defining a direction perpendicular to the axial direction, which abut against the gas generator holding wall 26 to maintain a generally parallel orientation. Perhaps more preferably, the protruding portion 56 includes at least three legs 58, each extending outward from a common point 60 in a direction parallel to the gas generator holding wall 26. In the illustrated embodiment, the protruding portion has a cross-shaped form with four legs 58, each extending outward from the common point 60 in a direction parallel to the gas generator holding wall 26. Each leg 58 may have a generally convex shape. It should be understood that the legs 58 of the protruding portion 56 may alternatively be spaced apart from each other (i.e., not connected to each other through the common point 60).

[0035] At least one of the protrusions 56 of the gas generator retaining wall 26 and the cap 46 may be made of a material that partially deforms when the cap 46 moves from a first position to a second position under the heat and pressure of the reaction. This partial deformation can increase the surface area contact between the cap 46 and the gas generator retaining wall 26 to prevent the cap 46 from tilting, while maintaining the combustion gas flow path between the cap and the gas generator retaining wall. In one embodiment, the cap 46 may be made of carbon steel, and the gas generator retaining wall may similarly be made of carbon steel.

[0036] A filter 62 is disposed in a filter chamber 22 to filter combustion gases before they are discharged through a radially extending port 64 in a second portion 16 of the housing 12. The second portion 16 of the housing 12 may be a diffuser cover portion. The filter 62 includes a body 66 and an opening 68 axially extending through the body 66. The opening 68 has a first end 70 at a first axial side 72 of the body portion 66 and a second end 74 at a second axial side 76 of the body portion 66. The first end 70 of the opening 68 has a first diameter D1. The second end 74 has a second diameter D2. The second diameter D2 is larger than the first diameter D1.

[0037] The opening 68 includes a first axial extension 68A extending inwardly from a first axial side 72 into the main body portion 66 and a second axial extension 68B extending inwardly from a second axial side 76 into the main body portion 66. The first axial extension 68A may have a cylindrical shape. The second axial extension 68B may have a truncated conical shape. The truncated conical shape of the second axial extension 68B may taper outwardly from a first diameter D1 adjacent to the first axial extension 68A to a second diameter D2 at the second end 74. The second axial extension 68A may taper outwardly at an angle α.

[0038] In one specific application, the first axial extension 68A has a first height H1 of approximately 3.5 mm, the second axial extension 68B has a second height H2 of approximately 7.2 mm, and the second axial extension 68A is tapered outward at an angle between 45 degrees and 70 degrees, and more preferably at an angle of approximately 60 degrees. In this particular example, the first diameter D1 of the first end 70 of the opening 68 is approximately 19.5 mm, and the second diameter D2 of the second end 74 of the opening 68 is approximately 27.8 mm.

[0039] The opening 68 of the filter 62 may alternatively include a stepped shape. In this respect, the opening 68 may alternatively be defined by one or more cylindrical portions of different diameters. For example, the second axial extension 68B of the opening 68 may alternatively be cylindrical in shape, having a stepped portion between the first axial extension 68A and the second axial extension 68B.

[0040] Filter 62 may include a first filter portion 62A radially surrounding a first axially extending portion 68A and a second filter portion 62B radially surrounding a second axially extending portion 68B. The first filter portion 62A may have a first radial density in the radial direction, and the second filter portion may have a second radial density in the radial direction. The second radial density may be greater than the first radial density, such that combustion gases flow radially through the first filter portion 62A more readily than through the second filter portion 62B. The second filter portion 68B may have a variable density in the radial direction that increases from the first filter portion 62A to the second axial side 76 of the filter 62. The variable density of the second filter portion 68B may increase linearly from adjacent to the first filter portion 62A to the second axial side 76 of the filter 62.

[0041] The filter 62 may be made of metal. More preferably, the filter may be a woven wire mesh filter. The truncated conical shape of the portion of the opening 68 passing through the second filter portion 62B may be defined by a mandrel of a corresponding shape. In this respect, the mandrel (not shown) used to create the truncated conical shape of the second axially extending portion 68B of the opening 68 may have a convex truncated conical shape corresponding to the shape of the second axially extending portion 68B. The wire mesh filter 62 may be compressed from its initial generally annular shape by the mandrel inserted into the opening 68. Compressing the wire mesh of the filter 62 with the mandrel may simultaneously compress the wire mesh of the first filter portion 62A and the second filter portion 62B axially and radially. When the wire mesh of the first filter portion 62A is not radially compressed (or at least radially compressed to a lesser extent), the density of the second filter portion 62B is greater than the density of the first filter portion 62A.

[0042] A partition member 78 disposed within the housing 12 axially separates the filter chamber 22 and the combustion chamber 24. The partition member 78 includes a plate portion 78A disposed adjacent to a first axial side 72 of the filter 62. The plate portion 78A may include a weakening zone 80. The weakening zone 80 may be adapted to open in response to an increase in pressure within the combustion chamber 24. Figure 1 and Figure 7A The image shows the weakened region 80 before it is opened. Figure 2 and Figure 7B The weakening zone 80 after opening is shown. In the illustrated embodiment, the weakening zone 80 has a cross-shaped form. Thus, the weakening zone 80 opens to define four lobes 82. However, it should be understood that, within the scope of this teaching, alternating shapes of the weakening zone can be used to define more or fewer lobes 82. After the weakening zone 80 opens, the plurality of lobes 82 of the plate portion 78A extend axially into the filter chamber 22. The size and position of the first axial extension portion 68A of the filter 62 are set to block radial movement of the plurality of lobes 82 when the weakening zone 80 is open. When the weakening zone is open, the lobes 82 of the plate portion 78A are radially spaced from the second diameter of the second axial extension portion 68B of the opening 68.

[0043] A heat insulation member 84 is axially disposed between the filter 62 and the second housing portion 16. Combustion gases passing through the filter 62 raise its temperature. The heat insulation member 84 includes a plate portion 86 having a plurality of vent holes 88. The heat insulation member 84 serves to protect the second housing portion 16 from these elevated filter temperatures. In the illustrated embodiment, the heat insulation member 84 is coupled to a partition member 78 such that the heat insulation member 84 is radially and axially captured by the partition member 78.

[0044] The partition member 78 and the heat insulation member 84 are cooperatively configured to be joined together. In this respect, the partition member includes a circumferential flange extending axially from the plate portion 78A in a direction away from the combustion chamber 24. The heat insulation member 84 includes a plurality of engaging elements 90. The engaging elements 90 may be hook-shaped engaging elements, the size and position of which are configured to press-fit into the partition member 78. The hook-shaped engaging elements 90 extend axially from the circumferential flange 92, which extends axially from the plate portion 86 of the heat insulation member 84. In the illustrated embodiment, the heat insulation member 84 includes four (4) engaging elements 90, which are circumferentially equidistantly spaced around the heat insulation member. While hook-shaped engaging elements 90 may be preferred for a particular application, it should be understood that other types of engaging elements may be incorporated within the scope of this teaching. It should also be understood that the engaging elements 90 may alternatively be carried by the partition member 78.

[0045] The filter 62 is axially trapped between the insulation member 84 and the partition member 78, such that movement of the filter 62 within the filter chamber 22 is directly blocked in a first axial direction by the plate portion 86 of the insulation member 84, and in the opposite second axial direction by the plate portion 78A of the partition member 78. The filter 62 is radially trapped by at least one of the insulation member 84 and the partition member 78, such that movement in any radial direction is blocked. In the illustrated embodiment, radial movement of the filter 62 within the filter chamber 22 is directly blocked by the circumferential flange 92 of the insulation member 84.

[0046] Specific reference Figure 1 and Figure 2 A cross-sectional view will be provided to illustrate the operation of the inflator 10 described in this teaching. The flow of combustion gases is... Figure 1A Arrows are used to indicate this. However, it should be understood that... Figure 1A The arrows included in the diagram indicate the main flow of combustion gases through the inflator 10 in a simplified manner.

[0047] When the inflator 10 is activated, the first gas generating agent material 30 ignites and generates charging gas, which pressurizes the first portion 28 of the combustion chamber 24. The increased pressure within the first portion 28 of the combustion chamber 24 opens the weakened zone 80 of the plate portion 78A of the separating member 78, causing the flaps 82 to extend into the filter chamber 22. More specifically, the flaps 82 of the plate portion 78A extend into the opening 68 of the filter 62. Figure 1A As shown, the flaps 82 continue to open until they are radially blocked at the first axial extension 68A of the opening 68 by the first portion 62A of the filter 62. Thus, the flaps 82 are radially spaced from the second portion 62B of the filter 62 at the second axial extension 68B of the opening 68, allowing unobstructed radial flow of the combustion gases. The combustion gases from the first gas generating agent material 30 pass radially through the filter 62 and are discharged through the radially extending port 64. Considering the lower density of the filter 62 at the first portion 62A, the flow of the combustion gases passes radially not only through the second portion 62B of the filter 62 but also through the first portion 62A. It should be understood that the reduced diameter of the opening 68 of the filter 62 is used to impede the movement of the flaps 82, thereby reducing the variability of the performance of the inflator 10.

[0048] When the second ignition device 42 is activated, the second gas generating agent material 34 is activated to generate a second charging gas source. When the second gas generating agent material 34 is activated, the second combustion gas source pressurizes the second portion 32 of the combustion chamber 24. The increased pressure within the second portion 32 of the combustion chamber 24 causes the cover 46 to shift from a closed position to an open position. A flow path is maintained between the cover 46 and the gas generating agent holding wall 26. Furthermore, it should be understood that this flow path maintained between the cover 46 and the gas generating agent holding wall 26... Figure 1A This is not specifically indicated by arrows. However, it will be further understood that this flow path further reduces the variability of the performance of the inflator 10. Combustion gas from the second gas generating agent material 34 similarly enters axially through the opening 36 in the gas generating agent retaining wall, through the opening in the plate portion 78A of the separating member 78, through the opening 68 in the filter 62, through the filter 62 radially, and exits at the port 64.

[0049] 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. An inflator (10) for generating inflation gas for a safety device, the inflator (10) comprising: A housing (12) having an inner cavity including a combustion chamber (20) and a filter chamber (22); A filter (62) is disposed in the filter chamber (22); A separating member (78) is disposed on the first axial side (72) of the filter (62) in the housing (12) and separates the filter chamber (22) from the combustion chamber (20); A heat insulation component (84) is disposed on the second axial side (76) of the filter (62) within the filter chamber (22), the second axial side (76) being opposite to the first axial side (72). The feature is that the separating member (78) is connected to the heat insulation member (84).

2. The inflator (10) according to claim 1, characterized in that, The partition member (78) includes a plate portion (78A) having a weakened zone (80) that opens in response to an increase in pressure within the combustion chamber (20).

3. The inflator (10) according to claim 2, characterized in that, The weakening zone (80) opens in response to the increase in pressure within the combustion chamber (20) to form a plurality of lobes (82) extending axially into the filter chamber (22).

4. The inflator (10) according to claim 3, characterized in that, The filter (62) includes an axially extending opening (68), and the plurality of lobes (82) extend axially into the axially extending opening (68).

5. The inflator (10) according to any one of the preceding claims, characterized in that, The thermal insulation member (84) is radially and axially captured by the partition member (78).

6. The inflator (10) according to claim 5, characterized in that, The heat insulation member (84) and the partition member (78) are press-fitted together.

7. The inflator (10) according to any one of the preceding claims, characterized in that, The thermal insulation member (84) includes a plurality of engagement elements (90) that engage with the partition member (78).

8. The inflator (10) according to claim 7, characterized in that, The plurality of engagement elements (90) are hook-shaped engagement elements press-fitted into the separator member (78).

9. The inflator (10) according to any one of the preceding claims, characterized in that, The filter (62) is axially trapped between the insulation member (84) and the partition member (78).

10. The inflator (10) according to any one of the preceding claims, characterized in that, The filter (62) is radially captured by at least one of the insulation member (84) and the separation member (78).

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