US20020109339A1

US20020109339A1 - Air bag inflator with initiator retainer

Info

Publication number: US20020109339A1
Application number: US09/780,751
Authority: US
Inventors: Ahmad Al-Amin
Original assignee: TRW Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 2001-02-09
Filing date: 2001-02-09
Publication date: 2002-08-15
Also published as: US6830264B2; DE10204627B4; US20020109340A1; DE10204627A1

Abstract

An inflator (10) comprises a container (30) in which inflation fluid is stored under pressure. The container (30) has an opening (40) through which inflation fluid flows from the container. A rupturable closure member (60) is fixed to the container (30) and blocks flow of inflation fluid through the opening (40). The inflator includes an initiator (70) for, when actuated, rupturing the closure member (60) to enable inflation fluid to flow from the container through the opening (40). The inflator (10) also includes a retainer (90) for retaining the initiator (70) on the container (30). The retainer (90) comprises first and second parts (92, 94) that are movable relative to each other when the retainer is not connected with the container (30). The first and second retainer parts (92, 94) when connected with the container (30) cooperate to clamp the initiator (70) in position on the container. The first and second retainer parts (92, 94) define a fluid outlet (108, 140) through which inflation fluid flows from the opening (40) to exit the inflator (10).

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an inflator that provides inflation fluid to inflate an inflatable vehicle occupant protection device and, more specifically, to an initiator retainer for an air bag inflator.

2. Description of Related Art

An inflatable vehicle occupant protection device, such as an air bag, is inflated upon the occurrence of a vehicle condition requiring inflation of the air bag. When inflation is required, an inflator is actuated to provide inflation fluid, which inflates the air bag into the vehicle occupant compartment.

The inflator includes a container defining an inflation fluid pressure chamber with an outlet passage. A rupturable closure member is fixed to the container to block flow of inflation fluid through the outlet passage. The inflator further includes an electrically actuatable initiator which, when actuated, causes the closure member to rupture so that inflation fluid in the pressure chamber can flow from the inflator. In some applications, it is desirable that the inflation fluid exit the inflator in a direction parallel to a longitudinal axis of the inflator.

SUMMARY OF THE INVENTION

The present invention is an inflator for inflating an inflatable vehicle occupant protection device. The inflator comprises a container in which inflation fluid is stored under pressure. The container has an opening through which inflation fluid flows from the container. A rupturable closure member is fixed to the container and blocks flow of inflation fluid through the opening. The inflator includes an initiator for, when actuated, rupturing the closure member to enable inflation fluid to flow from the container through the opening. The inflator also includes a retainer for retaining the initiator on the container. The retainer comprises first and second parts that are movable relative to each other when the retainer is not connected with the container. The first and second retainer parts, when connected with the container, cooperate to clamp the initiator in position on the container. The first and second retainer parts define a fluid outlet through which inflation fluid flows from the opening to exit the inflator. In one embodiment, the inflation fluid exits the inflator in a direction parallel to a longitudinal central axis of the inflator.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, in which: [0007]
FIG. 1 is a schematic illustration of a vehicle occupant protection apparatus embodying the present invention; [0008]
FIG. 2 is an enlarged sectional view of an inflator that forms part of the apparatus of FIG. 1; [0009]
FIG. 3 is a further enlarged view of a portion of the inflator of FIG. 2; and [0010]
FIG. 4 is a view similar to FIG. 2 showing an inflator in accordance with a second embodiment of the invention; and [0011]
FIG. 5 is a view similar to FIG. 2 showing an inflator in accordance with a third embodiment of the invention.[0012]

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a vehicle occupant protection apparatus. In particular, the present invention relates to an inflator for an inflatable vehicle occupant protection device. As representative of the present invention, FIG. 1 illustrates an [0013] inflator 10 that forms part of a vehicle protection apparatus 11 for helping to protect an occupant of a vehicle 12.
The [0014] protection apparatus 11 includes an inflatable vehicle occupant protection device in the form of a side curtain 14. The side curtain 14 is mounted adjacent the side structure 16 of the vehicle 12. A fill tube 20 extends into the side curtain 14. The inflator 10, when actuated, directs fluid into the fill tube 20 which, in turn, directs fluid into the inflatable side curtain 14 to inflate the side curtain. The side curtain 14 is inflated from a deflated and stowed condition (not shown) to an inflated condition, as illustrated in FIG. 1. In its inflated condition, the side curtain 14 is positioned between the side structure 16 of the vehicle 12 and a vehicle occupant. The side curtain 14 is made of a material having a low permeability so that the side curtain remains inflated for a long period of time, such as seven seconds or longer.
The [0015] vehicle 12 includes a sensor 24, known in the art, for sensing a side impact to the vehicle and/or a vehicle rollover, to actuate the inflator 10. The sensor 24 may include vehicle electric circuitry for actuating the inflator 10 in response to sensing a side impact to the vehicle and/or a vehicle rollover. The sensor 24 provides an electric signal over lead wires 26 to the inflator 10, when the inflator is to be actuated.
The inflator [0016] 10 (FIG. 2) comprises a source of inflation fluid for the side curtain 14. The inflator 10 includes a container 30 having a generally elongate configuration including a main body portion 32. The main body portion 32 of the container 30 has a tubular, cylindrical configuration including an axially extending, cylindrical side wall 34. The side wall 34 is centered on a longitudinal central axis 36 of the inflator 10.
A [0017] first end wall 38 of the main body portion 32 has an opening 40. The first end wall 38, an opposite second end wall 42, and the side wall 34 define a chamber 44 in the container 30.
An [0018] end cap 50 is affixed to the first end wall 38 of the main body portion 32, at a location extending across the opening 40. The end cap 50 is connected to the main body portion 32 in any suitable manner known in the art, such as by friction welding, laser welding, brazing or screw threads. The end cap 50 (FIGS. 2 and 3) has a generally cup-shaped configuration including an axially extending, cylindrical side wall 52 and an annular end wall 54.
A [0019] rupturable closure member 60, such as a rupture disk, is affixed to the end wall 54 of the end cap 50 by a laser weld. The rupture disk 60 could, however, be connected to the end cap 50 in any manner well known in the art, such as by brazing, projection welding or electron beam welding. The rupture disk 60 could also be formed in one piece with the end cap 50. The rupture disk 60 is centered on the axis 36 and blocks fluid flow through the opening 40.
The [0020] chamber 44 contains pressurized inflation fluid. The inflation fluid stored in the chamber 44 preferably includes helium at a storage pressure within the range of about 4,000 psi to about 7,000 psi. The inflation fluid may, however, have any other composition and storage pressure suitable for inflating the side curtain 14.
The [0021] inflator 10 includes an initiator 70. The initiator 70 is of a known design including a support portion 72 (FIG. 3) and a cylindrical main body portion 74 that projects from the support portion. The main body portion 74 and the support portion 72 of the initiator 70 are covered in a deformable material 76, such as molded nylon.
The [0022] support portion 72 of the initiator 70 has first and second frustoconical surfaces 78 and 80 that extend, in opposite directions along the axis 36, from a cylindrical outer side surface 82 of the support portion. A pair of terminal pins 84 extend from the support portion 72, in a direction away from the main body portion 74 of the initiator 70.
The [0023] inflator 10 includes a retainer 90 for retaining the initiator 70 on the container 30. The retainer 90 includes first and second retainer parts 92 and 94. The first and second retainer parts 92 and 94 are separate members that are movable relative to each other when they are not connected with the container 30.
The [0024] first retainer part 92, or inner retainer part, is made from metal and has a disc-shaped main body portion 100 including parallel, radially extending inner and outer major side surfaces 102 and 104. A mounting flange 106 extends radially outward from the main body portion 100.
A plurality of [0025] fluid outlet openings 108 are formed in the main body portion 100 of the first retainer part 92. The fluid outlet openings 108, two of which are shown in the drawings, are circular in shape and are disposed in a circular array centered on the axis 36. The fluid outlet openings 108 extend axially between the inner and outer major side surfaces 102 and 104.
The [0026] first retainer part 92 has a central surface 110 that defines a central opening 112 in the first retainer part. One portion 114 of the central opening 112 is formed as an annular notch, opening into the outer side surface 104, for receiving a portion of the initiator 70, as described below. Another portion 116 of the central opening 112 is formed as an annular notch, opening into the inner side surface 102, for receiving a portion of a support barrel 150, as described below.
The [0027] second retainer part 94, or outer retainer part, is made from metal and has a main body portion 120 with a radially extending inner major side surface 121. A mounting flange 122 extends radially outward from the main body portion 120. The mounting flange 122 on the second retainer part 94 is the same diameter as the mounting flange 106 on the first retainer part 92.
The [0028] second retainer part 94 includes cylindrical inner and outer walls 124 and 126 that extend parallel to the axis 36. The inner and outer walls 124 and 126 define between them an annular collection chamber 128. The inner wall 124 defines, radially inward of the inner wall, a chamber 130 for receiving a portion of the initiator 70. The inner wall 124 has a frustoconical surface 132 centered on the axis 36.
The [0029] second retainer part 94 includes an outlet tube 140. The outlet tube 14 has a cylindrical configuration and projects from the second retainer part 94, at one circumferential location on the second retainer part. The outlet tube 140 extends parallel to the longitudinal central axis 36 of the inflator 10. The outlet tube 140 is in fluid communication with the collection chamber 128, so that fluid flowing into the collection chamber can exit the second retainer part 94 through the outlet tube.
The [0030] support barrel 150 is made from metal and has a cylindrical side wall 152 with a first end portion 154. The side wall 152 is capped at its end opposite the first end portion 154 by a radially extending end wall 156. A circular central opening 158 is formed in the end wall 156 of the support barrel 150.
The [0031] inflator 10 is assembled by first welding the rupture disk 60 to the end cap 50. The subassembly of the end cap 50 and rupture disk 60 is then welded to the main body portion 32 of the container 30.
The [0032] end portion 154 of the side wall 152 of the support barrel 150 is pressed into the notch 116 in the inner side surface 102 of the first retainer part 92. The support barrel 150 is, thereby, positioned on the first retainer part 92 for movement with the first retainer part.
The subassembly of the [0033] first retainer part 92 and the support barrel 150 is inserted into the end cap 50 of the inflator 10. The main body portion 100 of the first retainer part 92 has an interference fit with the side wall 52 of the end cap 50. The mounting flange 106 of the first retainer part 92 engages a stop surface 160 on the side wall 52. The end wall 156 of the support barrel 150 is located adjacent the closure member 60.
The [0034] initiator 70 is then fitted into the central opening 110 of the first retainer part 92. The initiator 70 is self-centering in the first retainer part 92. The support portion 72 of the initiator 70 is received in the notch 114 in the first retainer part 92. The main body portion 74 of the initiator 70 extends within the support barrel 150.
The [0035] second retainer part 94 is then fitted onto the container 30. The frustoconical surface 132 on the second retainer part 94 engages the support portion 72 of the initiator 70. The inner major side surface 121 of the second retainer part 94 engages the outer major side surface 104 of the first retainer part 92. The mounting flanges 106 and 122 of the retainer parts 92 and 94 overlie each other.
A projecting [0036] portion 162 of the end wall 52 of the end cap 50 is deformed radially inwardly and crimped onto the mounting flange 122 of the second retainer part 94 to secure the retainer 90, and thereby the initiator 70, on the container 30. Alternatively, the retainer 90 may be welded to the end cap 50 of the container 30.
The [0037] initiator 70 is thus clamped between the first retainer part 92 and the second retainer part 94. The metal from which the first and second retainer parts 92 and 94 are made presses into, and deforms, the plastic outer covering of the support portion 72 of the initiator 70. This engagement of the retainer 90 with the initiator 70 creates a fluid-tight seal between the initiator and the retainer.
When the [0038] chamber 44 is not filled with inflation fluid, the closure member 60 is a flat disk and is spaced from the end wall 156 of the support barrel 150. During the subsequent loading of the closure member 60 by the pressure of inflation fluid introduced into the chamber 44 through a fill opening (not shown), the closure member is stressed and undergoes plastic deformation into contact with the end wall 156 of the support barrel 150. The closure member 60 deforms into the shape shown in FIG. 3.
The force of the inflation fluid in the [0039] chamber 44, acting on the closure member 60, presses the support barrel 150 firmly into engagement with the first retainer part 92. The support barrel 150 is thus mounted in a load bearing relationship between the closure member 60 and the first retainer part 92. The first retainer part 92, in turn, transmits the storage pressure force through the second retainer part 94 to the end cap 50.
Upon receipt of an electric signal from the [0040] sensor 24, the initiator 70 is actuated in a known manner to produce a shock wave and combustion products. The shock wave and combustion products flow through the interior of the support barrel 150 into engagement with the closure member 60 and rupture the closure member. Inflation fluid flows through the opening 40 in the container 30 and into the end cap 50. The inflation fluid then flows through the fluid outlet openings 108 in the first retainer part 92 and into the collection chamber 128 of the second retainer part 94. The collection chamber 128 of the second retainer part 94 directs the inflation fluid into the outlet tube 140. The inflation fluid exits the inflator 10 through the outlet tube 140 and thereafter flows to the side curtain 14 to inflate the side curtain. The inflation fluid exits the inflator 10 in a direction parallel to the longitudinal axis 36 of the inflator.
FIG. 4 illustrates a portion of an inflator [0041] 10 a constructed in accordance with a second embodiment of the invention. Portions of the inflator 10 a that are the same as, or similar to, corresponding portions of the inflator 10 are given the same reference numerals with the suffix “a” attached.
In the inflator [0042] 10 a, an initiator 70 a is clamped between first and second retainer parts 92 a and 94 a. The second retainer part 94 a does not include a fluid outlet tube, like the fluid outlet tube 140 (FIG. 3). Instead, the second retainer part 94 a (FIG. 4) has a plurality of fluid outlet openings 166 that are aligned with fluid outlet openings 108 a in the first retainer part 92 a. The fluid outlet openings 166 in the second retainer part 94 a open into a chamber 168 in a diffuser 170.
The [0043] diffuser 170 is a tubular member, preferably made from sheet metal, that is crimped onto the end cap 50 a. The diffuser 170 has a relatively wide collection portion 172 that extends around the retainer 90 a and the initiator 70 a. An outlet tube 174 extends from the collection portion 172.
Operation of the inflator [0044] 10 a is similar to operation of the inflator 10. When the initiator 70 a is actuated, the combustion products of the initiator are directed through the support barrel 150 a into engagement with the closure member 60 a. The closure member 60 a ruptures, enabling inflation fluid to flow into the end cap 50 a, through the aligned openings 108 a and 166 in the retainer parts 92 a and 94, into the chamber 168 of the diffuser 170. The inflation fluid flows out of the inflator 10 a through the outlet tube 174 of the diffuser 170, in a direction parallel to the longitudinal axis 36 a of the inflator.
FIG. 5 illustrates a portion of an inflator [0045] 10 b constructed in accordance with a third embodiment of the invention. Portions of the inflator 10 b that are the same as, or similar to, corresponding portions of the inflator 10 are given the same reference numerals with the suffix “b” attached.
The inflator [0046] 10 b includes a retainer 90 b. The retainer 90 b comprises a first retainer part in the form of a support barrel 150 b, and a second retainer part 94 b. The second retainer part 94 b has a configuration similar to that of the second retainer part 94 a of the inflator 10 a (FIG. 4). The second retainer part 94 b (FIG. 5) supports an initiator 70 b having a deformable plastic covering 76 b.
The [0047] second retainer part 94 b has an annular notch 116 b that is presented toward the closure member 60 b. The notch 116 b receives a flared end portion 154 b of a support barrel 150 b. The end portion 154 b of the support barrel 150 b also engages the plastic covering 76 b of the initiator 70 b. The dimensions of the support barrel 150 b, initiator 70 b, and second retainer part 94 b are selected so that, in assembly of the inflator 10 b, the support barrel initially presses against only the initiator, and not the second retainer part, until the fluid force on the closure member 60 b loads the support barrel 150 b. As a result, the flared end portion 154 of the support barrel 150 b effects a fluid tight-seal against the initiator 70 b.
From the above description of the invention, those skilled in the art may perceive improvements, changes and modifications in the invention. For example, although the inflator [0048] 10 is shown being used with a side curtain 14, the inflator could be used in any known inflatable vehicle occupant protection device, such as frontal or side impact air bags, inflatable seat belts, inflatable knee bolsters, inflatable air bags to operate knee bolsters, and inflatable head liners. Also, the invention is applicable to inflators that do not use a support member, such as the support barrel 150, to support a rupturable member. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.

Claims

Having described the invention, I claim:

1. An inflator for inflating an inflatable vehicle occupant protection device, comprising:

a container in which inflation fluid is stored under pressure, said container having an opening through which inflation fluid flows from said container;

a rupturable closure member fixed to said container and blocking flow of inflation fluid through said opening;

an initiator for, when actuated, rupturing said closure member to enable inflation fluid to flow from said container through said opening; and

a retainer for retaining said initiator on said container, said retainer comprising first and second parts that are movable relative to each other when said retainer is not connected with said container;

said first and second retainer parts when connected with said container cooperating to clamp said initiator in position on said container;

said first and second retainer parts defining a fluid outlet through which inflation fluid flows from said opening to exit said inflator.

2. An inflator as set forth in claim 1 wherein said first and second retainer parts have aligned fluid outlet openings through which inflation fluid flows.

3. An inflator as set forth in claim 1 wherein said first and second retainer parts have adjacent mounting portions that are secured to said container to hold said retainer in position on said container.

4. An inflator as set forth in claim 1 wherein said first retainer part has a disk-shaped configuration including a central opening for receiving and supporting said initiator and at least one fluid outlet opening.

5. An inflator as set forth in claim 1 further comprising a support for said rupturable closure member, said rupturable closure member having a first portion deformed into engagement with said support by the pressure of said inflation fluid in said container, said support transmitting force from said closure member to said retainer.

6. An inflator as set forth in claim 1 wherein said first retainer part comprises a support for said rupturable closure member, said rupturable closure member having a first portion deformed into engagement with said support by the pressure of said inflation fluid in said container.

7. An inflator as set forth in claim 6 wherein said initiator when actuated generates combustion products and a shock wave that are directed through the interior of said support into engagement with said closure member to rupture said closure member.

8. An inflator as set forth in claim 1 wherein said first retainer part is received in said container with an interference fit to locate said first retainer part relative to said container, said initiator being supported on said first retainer part, and said second retainer part being self-centering on said initiator.

9. An inflator as set forth in claim 1 wherein said container has a longitudinal axis and said fluid outlet extends parallel to said longitudinal axis of said container.