U.S. patent application number 12/906219 was filed with the patent office on 2011-02-03 for inflators and method for manufacturing inflators.
This patent application is currently assigned to DELPHI TECHNOLOGIES, INC.. Invention is credited to VENKATASUBRAMANIAN ANANTHANARAYANAN, BRIAN T. FINNIGAN, JAMES M. PAYNE, DONALD E. WARREN.
Application Number | 20110025028 12/906219 |
Document ID | / |
Family ID | 40406249 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110025028 |
Kind Code |
A1 |
FINNIGAN; BRIAN T. ; et
al. |
February 3, 2011 |
INFLATORS AND METHOD FOR MANUFACTURING INFLATORS
Abstract
A closure assembly for an inflator comprises a housing and an
outlet plate disposed within the housing. The outlet plate has an
outlet opening configured to receive a burst disk. The outlet plate
is joined to the housing by a deformation resistance weld. The
deformation resistance weld is formed by contacting the outlet
plate with a first electrode, contacting an exterior portion of the
housing with a second electrode, and applying a voltage through the
first and second electrodes to adhere a portion of the housing to a
portion of the outlet plate.
Inventors: |
FINNIGAN; BRIAN T.;
(LEWISBURG, OH) ; ANANTHANARAYANAN;
VENKATASUBRAMANIAN; (BEAVERCREEK, OH) ; PAYNE; JAMES
M.; (GRAND BLANC, MI) ; WARREN; DONALD E.;
(TIPP CITY, OH) |
Correspondence
Address: |
Delphi Technologies, Inc.
M/C 480-410-202, P.O. Box 5052
Troy
MI
48007
US
|
Assignee: |
DELPHI TECHNOLOGIES, INC.
TROY
MI
|
Family ID: |
40406249 |
Appl. No.: |
12/906219 |
Filed: |
October 18, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11846219 |
Aug 28, 2007 |
7823918 |
|
|
12906219 |
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Current U.S.
Class: |
280/737 ;
219/148; 220/500 |
Current CPC
Class: |
B23K 11/3081 20130101;
Y10T 29/49826 20150115; B60R 21/274 20130101; B60R 2021/2685
20130101; B60R 21/268 20130101; B23K 2101/006 20180801 |
Class at
Publication: |
280/737 ;
219/148; 220/500 |
International
Class: |
B60R 21/261 20110101
B60R021/261; B23K 11/00 20060101 B23K011/00; B65D 25/04 20060101
B65D025/04 |
Claims
1. A method for securing an outlet plate within a housing of an
inflator, the method comprising: inserting the outlet plate into
the housing; applying pressure against the outlet plate with a
first electrode in a first direction; applying pressure against an
exterior portion of the housing with a second electrode in a second
direction; and welding the outlet plate to the housing by applying
a voltage through the first and second electrodes to adhere a
joining portion of the outlet plate to a joining portion of the
housing.
2. The method of claim 1, wherein the second direction is generally
perpendicular to the first direction.
3. The method of claim 1, wherein welding the outlet plate to the
housing comprises applying a first level of electrical current flow
through the outlet plate and the housing for a first period of time
to soften the respective joining portions by electrical resistance
heating and causing the softened joining portions to deform against
one another, and wherein welding the outlet plate to the housing
further comprises applying a second level of electrical current
higher than the first level of current for a second period of time
sufficient to at least partially melt the joining portions and form
a deformation resistance weld between the outlet plate and the
housing.
4. A method for securing a divider plate within an outer housing of
an inflator, the method comprising: inserting the divider plate
within the outer housing; inserting a first electrode into the
outer housing, the first electrode being configured to engage a
portion of the divider plate; applying pressure against the divider
plate with the first electrode in a first direction; applying
pressure against an exterior portion of the outer housing proximate
to the divider plate with a second electrode in a second direction;
and welding the divider plate to the outer housing by applying a
voltage through the first and second electrodes to adhere a joining
portion of the divider plate to a joining portion of the outer
housing.
5. The method of claim 4, wherein the second direction is generally
perpendicular to the first direction.
6. The method of claim 4, wherein welding the divider plate to the
outer housing comprises applying a first level of electrical
current flow through the outer housing and the divider plate for a
first period of time to soften the respective joining portions by
electrical resistance heating and causing the softened joining
portions to deform against one another, and wherein welding the
divider plate to the outer housing further comprises applying a
second level of electrical current higher than the first level of
current for a second period of time sufficient to at least
partially melt the joining portions and form a deformation
resistance weld between the outer housing and the divider
plate.
7. The method of claim 4, wherein the first electrode has an
opening configured to receive a centrally protruding portion of the
dividing plate therein, and wherein the second electrode has a pair
of members that when secured together define an annular member
having an inner opening configured to contact an exterior periphery
of the housing, and wherein the centrally protruding portion has an
orifice disposed therein, the orifice being configured to provide
fluid communication between a first chamber and the second chamber
of the housing.
8. A method for securing a base plate to an inflator housing of an
inflator, the method comprising: disposing the base plate proximate
to an open end of the inflator housing; applying pressure against
an exterior portion of the inflator housing proximate to the base
plate with a first electrode in a first direction; applying
pressure against the base plate with a second electrode in a second
direction; and welding the base plate to the inflator housing by
applying a voltage through the first and second electrodes to
adhere a joining portion of the base plate to a joining portion of
the inflator housing.
9. The method of claim 8, wherein the second direction is generally
perpendicular to the first direction.
10. The method of claim 8, wherein welding the base plate to the
inflator housing comprises applying a first level of electrical
current flow through the inflator housing and the base plate for a
first period of time to soften the respective joining portions by
electrical resistance heating and causing the softened joining
portions to deform against one another, and wherein welding the
base plate to the inflator housing further comprises applying a
second level of electrical current higher than the first level of
current for a second period of time sufficient to at least
partially melt the joining portions and form a deformation
resistance weld between the inflator housing and the base
plate.
11. A welding apparatus for deformation resistance welding a
divider plate within an outer housing of an inflation device, the
apparatus comprising: a first electrode configured to be inserted
into the outer housing, the first electrode having a contact end
with an opening configured to receive a centrally protruding
portion of the divider plate therein, the first electrode having an
outer periphery that is smaller than an inner dimension of the
housing; and a second electrode comprising a pair of members
removably secured to each other, the pair of members defining an
inner opening, the pair of members being configured to apply
pressure to an exterior surface of the outer housing when the pair
of members are secured to one another.
12. An inflator for inflating an inflatable cushion of an airbag
module, the inflator comprising: an outer housing; a divider plate
secured within the outer housing to define a first chamber and a
second chamber of the outer housing, the divider plate having an
orifice disposed therein, the orifice providing fluid communication
between the first chamber and the second chamber, the divider plate
being joined to the outer housing by a weldment disposed between
the outer housing and the divider plate; and a closure assembly
configured to seal the first chamber at a first end of the outer
housing, the closure assembly having a closure housing and an
outlet plate disposed within the closure housing, the outlet plate
having an outlet opening configured to receive a burst disk, the
outlet plate being joined to the closure housing by a second
weldment disposed between the closure housing and the outlet plate,
wherein the outer housing is joined to the outlet plate remote from
the closure housing at the first end of the outer housing, and
wherein the first chamber has a first volume of compressed
inflation gas and the second chamber has a second volume of
compressed inflation gas, the second volume being smaller than the
first volume, the second chamber being configured to route
compressed inflation gas therein to the first chamber through the
orifice of the divider plate.
13. A method for securing a first member within a generally tubular
second member, the method comprising: inserting the first member at
least partially into the second member; applying pressure against
the first member with a first electrode in a first direction;
applying pressure against an exterior portion of the second member
with a second electrode in a second direction; and welding the
first member to the second member by applying a voltage through the
first and second electrodes to adhere a joining portion of the
first member to a joining portion of the second member.
14. The method of claim 13, wherein the second direction is
generally perpendicular to the first direction.
15. The method of claim 13, wherein welding the first member to the
second member comprises applying a first level of electrical
current flow through the first member and the second member for a
first period of time to soften the respective joining portions by
electrical resistance heating and causing the softened joining
portions to deform against one another, and wherein welding the
first member to the second member further comprises applying a
second level of electrical current higher than the first level of
current for a second period of time sufficient to at least
partially melt the joining portions and form a deformation
resistance weld between the first member and the second member.
16. A method for securing a first member within a generally tubular
second member, the method comprising: inserting the first member
within the second member; inserting a first electrode into the
second member, the first electrode being configured to engage a
portion of the first member; applying pressure against the first
member with the first electrode in a first direction; applying
pressure against an exterior portion of the second member proximate
to the first member with a second electrode in a second direction;
and welding the first member to the second member by applying a
voltage through the first and second electrodes to adhere a joining
portion of the first member to a joining portion of the second
member.
17. The method of claim 16, wherein the second direction is
generally perpendicular to the first direction.
18. The method of claim 16, wherein welding the first member to the
second member comprises applying a first level of electrical
current flow through the second member and the first member for a
first period of time to soften the respective joining portions by
electrical resistance heating and causing the softened joining
portions to deform against one another, and wherein welding the
first member to the second member further comprises applying a
second level of electrical current higher than the first level of
current for a second period of time sufficient to at least
partially melt the joining portions and form a deformation
resistance weld between the first member and the second member.
19. The method of claim 16, wherein the first electrode has an
opening configured to receive a centrally protruding portion of the
first member therein, and wherein the second electrode has a pair
of members that when secured together define an annular member
having an inner opening configured to contact an exterior periphery
of the second member.
20. A method for securing a first member to a generally tubular
second member, the method comprising: disposing the first member
proximate to an open end of the second member applying pressure
against an exterior portion of the second member proximate to the
first member with a first electrode in a first direction; applying
pressure against the first member with a second electrode in a
second direction; and welding the first member to the second member
by applying a voltage through the first and second electrodes to
adhere a joining portion of the first member to a joining portion
of the second member.
21. The method of claim 20, wherein the second direction is
generally perpendicular to the first direction.
22. The method of claim 20, wherein welding the first member to the
second member comprises applying a first level of electrical
current flow through the second member and the first member for a
first period of time to soften the respective joining portions by
electrical resistance heating and causing the softened joining
portions to deform against one another, and wherein welding the
first member to the second member further comprises applying a
second level of electrical current higher than the first level of
current for a second period of time sufficient to at least
partially melt the joining portions and form a deformation
resistance weld between the second member and the first member.
23. A welding apparatus for deformation resistance welding a first
member within a generally tubular outer member, the apparatus
comprising: a first electrode configured to be inserted into the
outer member, the first electrode having a contact end with an
opening configured to receive a centrally protruding portion of the
first member therein, the first electrode having an outer periphery
that is smaller than an inner dimension of the outer member; and a
second electrode comprising a pair of members removably secured to
each other, the pair of members defining an inner opening, the pair
of members being configured to apply pressure to an exterior
surface of the outer member when the pair of members are secured to
one another.
24. An assembly comprising: a first generally tubular member; a
second member secured within the first member to define a least one
chamber, the second member being joined to the first member by a
weldment disposed between the first member and the second member;
and a third member configured to seal the at least one chamber
adjacent a first end of the first member, the third member being
joined to the first member by a second weldment disposed between
the third member and the first member.
Description
BACKGROUND
[0001] The present invention relates to pressurized containers, and
more specifically, to airbag cushion inflators and to apparatuses
and methods for manufacturing the same.
[0002] It is known to provide an inflatable restraint system
including an inflator and inflatable airbag cushion for protecting
the occupants of a transportation vehicle during collisions.
Automotive vehicles, for example, can be supplied with driver side
airbag modules, passenger side airbag modules, and side airbag
modules. Such airbag assemblies, for example, may be located within
the hub of the steering wheel and in a recess in the instrument
panel for protection of the vehicle occupants seated in opposing
relation to such assemblies. In other examples, such airbag
assemblies may be located within the seats and/or door panels for
protection of the occupants during a side-impact event.
[0003] Methods for manufacturing airbag inflators typically require
the welding of a number of parts together, particularly in light of
the increasing complexity of inflators. Prior welding techniques
used to manufacture airbag inflators have been either laser welding
or friction welding.
[0004] Laser welding is a welding technique used to join multiple
pieces of metal through the use of a laser. The beam provides a
concentrated heat source, allowing for narrow, deep welds and high
welding rates. The process is frequently used in high volume
applications, such as in the automotive industry. Some of the
shortcomings of laser welding are the very high cost of equipment
and consumables such as shielding gas and lenses, high cycle time,
uncertainty of consistently making a leak-tight joint, and somewhat
low weld strength with a potential for porosity (due to high
cooling rates, cracking can be a concern, especially when welding
high-carbon steels).
[0005] Friction welding is a technique used to weld thermoplastics
or metals by the heat generated through mechanical friction by
rubbing the members to be joined against each other under pressure,
with the addition of an upsetting force to plastically displace
material. Some of the shortcomings of friction welding are the high
cost of equipment, weld flash on both sides of the weld joint (some
of which may be loose and difficult to remove), difficulty in
controlling the finished part length upon welding, high cycle time,
and the difficulty of gripping thin plates using a friction welding
apparatus.
[0006] Accordingly, it is desirable to provide for the
manufacturing of airbag inflators using welding techniques that can
overcome at least some of the shortcomings of the prior welding
techniques.
SUMMARY OF THE INVENTION
[0007] Exemplary embodiments of the present invention relate to a
closure assembly for an inflator. The closure assembly comprises a
housing and an outlet plate disposed within the housing. The outlet
plate has an outlet opening configured to receive a burst disk. The
outlet plate is joined to the housing by a deformation resistance
weld. The deformation resistance weld is formed by contacting the
outlet plate with a first electrode, contacting an exterior portion
of the housing with a second electrode, and applying a voltage
through the first and second electrodes to adhere a portion of the
housing to a portion of the outlet plate.
[0008] Exemplary embodiments of the present invention also relate
to an inflator for inflating an inflatable cushion of an airbag
module. The inflator comprises an outer housing and a divider plate
secured within the outer housing to define a first chamber and a
second chamber of the outer housing. The divider plate has an
orifice disposed therein. The orifice provides fluid communication
between the first chamber and the second chamber. The divider plate
is joined to the outer housing by a deformation resistance weld.
The deformation resistance weld is formed by contacting the outer
housing with a first electrode at an exterior portion of the outer
housing proximate to the divider plate, contacting the divider
plate with a second electrode disposed within the outer housing,
and applying a voltage through the first and second electrodes to
adhere a portion of the outer housing to a portion of the divider
plate.
[0009] Exemplary embodiments of the present invention also relate
to an inflator for inflating an inflatable cushion of an airbag
module. The inflator comprises an inflator housing and a base plate
configured to engage with an assembly for mounting the inflatable
cushion to the airbag module. The base plate is joined to an open
end of the inflator housing by a deformation resistance weld. The
deformation resistance weld is formed by contacting the base plate
with a first electrode, contacting an exterior portion the inflator
housing with a second electrode proximate to the base plate, and
applying a voltage through the first and second electrodes to
adhere a portion of the inflator housing to a portion of the base
plate.
[0010] Exemplary embodiments of the present invention also relate
to a method for securing an outlet plate within a housing of an
inflator. The method comprises inserting the outlet plate into the
housing. The method further comprises applying pressure against the
outlet plate with a first electrode in a first direction. The
method further comprises applying pressure against an exterior
portion of the housing with a second electrode in a second
direction. The method further comprises welding the outlet plate to
the housing by applying a voltage through the first and second
electrodes to adhere a joining portion of the outlet plate to a
joining portion of the housing.
[0011] Exemplary embodiments of the present invention also relate
to a method for securing a divider plate within an outer housing of
an inflator. The method comprises inserting the divider plate
within the outer housing. The method further comprises inserting a
first electrode configured to engage a portion of the divider plate
into the outer housing. The method further comprises applying
pressure against the divider plate with the first electrode
electrode in a first direction. The method further comprises
applying pressure against an exterior portion of the outer housing
proximate to the divider plate with a second electrode in a second
direction. The method further comprises welding the divider plate
to the outer housing by applying a voltage through the first and
second electrodes to adhere a joining portion of the divider plate
to a joining portion of the outer housing.
[0012] Exemplary embodiments of the present invention also relate
to a method for securing a base plate to an inflator housing of an
inflator. The method comprises disposing the base plate proximate
to an open end of the inflator housing. The method further
comprises applying pressure against an exterior portion of the
inflator housing proximate to the base plate with a first electrode
in a first direction. The method further comprises applying
pressure against the base plate with a second electrode in a second
direction. The method further comprises welding the base plate to
the inflator housing by applying a voltage through the first and
second electrodes to adhere a joining portion of the base plate to
a joining portion of the inflator housing.
[0013] Exemplary embodiment of the present invention also relate to
a welding apparatus for deformation resistance welding a divider
plate within an outer housing of an inflation device. The apparatus
comprises a first electrode and a second electrode. The first
electrode is configured to be inserted into the outer housing. The
first electrode has a contact end with an opening configured to
receive a centrally protruding portion of the divider plate
therein. The first electrode has an outer periphery that is smaller
than an inner dimension of the housing. The second electrode
comprises a pair of members removably secured to each other. The
pair of members define an inner opening. The pair of members are
configured to apply pressure to an exterior surface of the outer
housing when the pair of members are secured to one another.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a side elevational view of an inflatable cushion
in a stored position;
[0015] FIG. 2 is a side elevational view of an inflatable cushion
in a deployed state;
[0016] FIG. 3 is a cross-sectional view of an inflator constructed
in accordance with an exemplary embodiment of the present
invention;
[0017] FIG. 4 is a cross-sectional view of an exemplary apparatus
after forming a deformation resistance weld between a closure
housing and an outlet plate of a closure assembly in accordance
with an exemplary embodiment of the present invention;
[0018] FIG. 5 is a partial cross-sectional view of the closure
housing and the outlet plate of FIG. 4 before the exemplary
deformation resistance weld is formed;
[0019] FIG. 6 is a partial cross-sectional view of the closure
housing and the outlet plate of FIG. 4 after the exemplary
deformation resistance weld is formed;
[0020] FIG. 7 is a cross-sectional view of an exemplary apparatus
prior to forming a deformation resistance weld between an outer
housing and a divider plate of an inflator in accordance with an
exemplary embodiment of the present invention;
[0021] FIG. 8 is a partial cross-sectional view of the exemplary
apparatus of FIG. 7 after forming the deformation resistance weld
between the outer housing and the divider plate of the inflator in
accordance with an exemplary embodiment of the present
invention;
[0022] FIG. 9 is a partial cross-sectional view of the outer
housing and the divider plate of FIGS. 7 and 8 after the exemplary
deformation resistance weld is formed;
[0023] FIG. 10 is a partial cross-sectional view of the outer
housing and the divider plate of FIGS. 7 and 8 after an alternative
exemplary deformation resistance weld is formed;
[0024] FIG. 11 is a cross-sectional view of an inflator constructed
in accordance with an alternative exemplary embodiment of the
present invention;
[0025] FIG. 12 is a view of the interior of an automotive vehicle
incorporating exemplary driver side and passenger side air bag
modules;
[0026] FIG. 13 is an exploded perspective view of an exemplary
driver side airbag module;
[0027] FIG. 14 is a partial cross-sectional view of an exemplary
apparatus prior to forming a deformation resistance weld between an
inflator housing and a base plate of an inflator assembly in
accordance with an exemplary embodiment of the present
invention;
[0028] FIG. 15 is a cross-sectional view of the exemplary apparatus
of FIG. 14 after forming the deformation resistance weld between
the inflator housing and the base plate of the inflator assembly in
accordance with an exemplary embodiment of the present invention;
and
[0029] FIG. 16 is a partial cross-sectional view of an exemplary
apparatus prior to forming a deformation resistance weld between an
inflator housing and a base plate of an inflator assembly in
accordance with an alternative exemplary embodiment of the present
invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0030] Exemplary embodiments of the present invention are directed
to devices for the containment and release of pressurized gas from
an airbag inflator, and to apparatuses and methods for
manufacturing the same. Particularly, as will be disclosed herein,
exemplary embodiments of the present invention are directed to
methods of manufacturing inflators using processes that involve the
welding of certain parts to each other using deformation resistance
welding techniques (DRW), and to inflators that have been
manufactured using these techniques.
[0031] DRW is a resistance welding method that has been developed
to join metal tubes to solids, sheet metal and other tubes. The
process atomically bonds metals and creates solid-state joints
through the heating and deformation of the mating surfaces. DRW can
be used to form near instantaneous, full strength, leak-tight welds
by heating metal surfaces only to the point of softening, followed
by rapid, engineered compression of the joint. Slight interference
at joint location facilitates deformation during weld process, but
is not essential. The process bonds metals and creates solid-state
joints without requiring filler welding material through the
heating and deformation of mating surfaces. DRW allows the joining
of not only similar, but also dissimilar materials (specifically
metals), providing designers with the ability to create lean
structural assemblies by using tubular components. For example,
contoured sheet metals can be welded to tubes.
[0032] DRW thus provides for more control over dimensions (in
particular, DRW can be utilized to obtain a predictable post-weld
member length) and can be used to create leak-tight joints that are
capable of holding fluids or gases under pressure and heat. These
joints can have strength exceeding that of the parent metals. The
DRW process can reduce the cycle time (which is independent of
joint size in DRW) and the cost it takes to make a variety of
structures that involve hollow members such as airbag inflators, as
will be described herein. The improved resistance welding method
increases design flexibility and efficiency while helping to cut
cost, investment, and part weight. Examples of deformation welding
techniques are described in detail in U.S. patent application Ser.
No. 10/253,099, published as Pub. No. 2004/0056001 on Mar. 25,
2004, U.S. patent application Ser. No. 10/914,837, published as
Pub. No. 2005/0006352 on Jan. 13, 2005, and U.S. patent application
Ser. No. 11/370,427, published as Pub. No. 2006/0231597 on Oct. 19,
2006, the disclosures of which are incorporated herein by
reference.
[0033] Referring now to FIG. 1, a non-limiting exemplary embodiment
of a side airbag or inflatable cushion 10 mounted to a vehicle 12
in a stored or non-deployed state is illustrated. In exemplary
embodiments, side airbag modules can comprise inflatable cushions
or curtains that traverse a side portion of the vehicle when they
are deployed in accordance with a predetermined activation event.
Generally, such a device is located along a side of the vehicle in
an uninflated state and, upon activation, deploys an inflatable
curtain along a side portion of the vehicle. Side impact airbags or
inflatable cushions are often mounted in close proximity to the
vehicle's roof rail, doorframe, center pillars, or, in some
instances, within the side door. Accordingly, the space or housing
for the uninflated airbag is typically compact and extends or
traverses along the window area or frame.
[0034] In the exemplary embodiment illustrated in FIG. 1, vehicle
12 comprises a front pillar 14, a rear pillar 16, and, if the
vehicle is so equipped (for example, it has more than one door per
side), a center pillar or pillars 18. Such pillars are commonly
referred to as A, B, C and D pillars. Inflatable cushion 10 is
stored and mounted on or proximate to a vehicle roof rail 20
beneath a headliner.
[0035] As illustrated, the rear portion of inflatable cushion 10 is
in fluid communication with a gas generator or inflator 30
positioned to provide an inflation gas to inflate inflatable
cushion 10 via a diffuser tube 31 having a plurality of diffuser
openings disclosed therein. It should, of course, be understood
that as applications may vary, the inflator may be positioned in
other locations than those illustrated in the present exemplary
embodiment. For example, the inflator may be located in a position
farther forward in the vehicle such as the door pillar, the front
pillar, or another location or locations. In addition, diffuser
tube 31 may be configured to extend through a portion of the
inflatable cushion, wherein a plurality of openings is positioned
in the diffuser tube that traverses through an interior portion of
the inflatable cushion. Thus, the presented location is provided as
an example and the present invention is not intended to be limited
by the same. In an alternative exemplary embodiment, the inflator
may be remotely located and a conduit or other fluid providing
means used to supply the inflating gas from the inflator to the
inflatable cushion.
[0036] In exemplary embodiments, inflatable cushion 10 may be
comprised of any airbag material suitable for holding gas. For
example, the inflatable cushion can comprise two sheets of woven
nylon fabric lined with urethane or other substantially impervious
material such as silicone. The two urethane coated nylon sheets in
this exemplary embodiment are secured to one another along an outer
periphery thereof to define the overall airbag shape. Prior to
deployment, the inflatable cushion is stored in a compartment
mounted to roof rail 20 or proximate to the roof rail as shown in
FIG. 1. To store inflatable cushion 10 in the compartment, the
uninflated cushion is folded into a configuration that allows it to
occupy a small discrete area within the vehicle interior.
[0037] FIG. 2 illustrates an exemplary embodiment of inflatable
cushion 10 in an inflated or deployed state. As illustrated in FIG.
2, inflatable cushion 10 comprises a deploying edge 22, which
comprises the bottom portion of the inflatable cushion that
traverses across the window openings or window frames of the
vehicle. Inflatable cushion 10 also comprises a forward edge 24, a
rearward edge 26 and a fixed edge 28. Fixed edge 28 represents the
portion of inflatable cushion 10 that remains in substantially the
same position regardless of whether the inflatable cushion is
deployed or not.
[0038] Many different types of airbags or inflatable cushion
arrangements (for example, internal cavities, tethers, and/or
seams) can be used with exemplary embodiments of the present
invention. Therefore, it should be understood that the
configuration of inflatable cushion 10 may vary and that the
illustrations in FIGS. 1 and 2 are provided as non-limiting
exemplary embodiments. The present invention is not intended to be
limited to the specific configurations provided herein in the
exemplary embodiments, as they are considered ancillary to the
present invention.
[0039] Referring now to FIG. 3, an exemplary embodiment of a side
airbag inflator 30 is illustrated. Inflator 30 comprises a
longitudinally extending, generally annular inflation housing 34, a
divider plate 80, an initiator 36, and an external closure assembly
78. Divider plate 80 is secured within inflation housing 34 to
define and partition a first inflation chamber 32 and a second
inflation chamber 76 within the inflation housing.
[0040] Closure assembly 78 of the present exemplary embodiment
includes a longitudinally extending, generally annular closure
housing 38, an annular outlet plate 40 that is joined to the
closure housing and secured to inflation housing 34 at one end of
first inflation chamber 32, and a burst disk 44. Outlet plate 40
defines an outlet opening 42 that is sealed by a burst disk 44 that
can comprise a thin metal membrane in exemplary embodiments. As
illustrated in FIG. 3, initiator 36 is mounted within closure
assembly 78.
[0041] In the present exemplary embodiment, closure housing 38 is
joined to outlet plate 40 using DRW techniques, as illustrated in
FIG. 4, to form a deformation resistance weld joint 41. Closure
housing 38 is generally annular and has an inside and an outside
surface 46, 47. Closure housing 38 also includes an upper end
flange 50 longitudinally extending from outside surface 47 of the
housing toward outlet plate 40.
[0042] Outlet plate 40, as shown in FIG. 4, is formed with a burst
disk flange 52 that extends radially inwardly in a direction
generally transverse to the annular wall of closure housing 38.
Burst disk flange 52 is configured to engage burst disk 44 so that
the burst disk will extend generally transversely to closure
housing 38 within the annulus of outlet plate 40. Outlet plate 40
is also formed with a lower end flange 54 extending longitudinally
from burst disk flange 52 in a direction generally opposed to upper
end flange 50 of closure housing 38. Lower end flange 54 is offset
radially inwardly in a direction generally transverse to upper end
flange 50 of closure housing 38 to define a recess 56 below the
outside portion of outlet plate 40.
[0043] Inside surface 46 and upper end flange 50 of closure housing
38 and the wall of outlet plate 40 adjacent to recess 56
respectively define the respective joining (that is, mating or
joining) surfaces of weld joint 41 between the closure housing and
the outlet plate. During the welding process, which is sequentially
illustrated in FIGS. 5 and 6, outside surface 47 of closure housing
38 is longitudinally aligned with the outside surface of outlet
plate 40. As best seen in FIG. 5, however, the transverse width of
the annular wall of closure housing 38 is greater than the
transverse width of recess 56 of outlet plate 40 at the outset of
the welding process. This differential provides for diametrical
interference in the mating parts to permit deformation and sliding
of the mating surfaces along each other during the weld process. In
the present exemplary embodiment, the upper end of inside surface
46 of closure housing 38 is provided with an angled chamfer 51 for
engaging lower end flange 54 of outlet plate 40 to prevent shorting
during initiation of the welding process. In the present exemplary
embodiment, angled chamfer 51 is provided with a relatively sharp
corner 55 to provide for high current density at the initiation of
the welding process.
[0044] With upper end flange 50 inserted into recess 56 and angled
chamfer 51 contacting lower end flange 54 of outlet plate 40, as
described above and shown in FIG. 5, weld joint 41 can then be
formed between closure housing 38 and the outlet plate. During the
welding process, a test plate may be provided to extend
transversely within the annulus of outlet plate 40 and simulate the
positioning of burst disk 44 in the completed inflator assembly.
The test plate may be configured to have an interstitial region to
simulate the electrode footprint in burst disk 44.
[0045] In the present exemplary embodiment, weld joint 41 is formed
by sliding inside surface 46 of closure housing 38 along lower end
flange 54 of outlet plate 40 while forcing the two components
against each other under sufficient pressure to form an
interference fit. As shown in FIG. 6, the welding process is
complete at a point at which upper end flange 50 engages outlet
plate 40. In this position, as shown in FIG. 6, the space between
upper end flange 50 and lower end flange 54 forms an expulsion or
flash trap 53, which is designed to improve the quality or the
cleanliness of weld joint 41 by preventing weld flash from reaching
the inner diameter of the functioning area of weld joint 41.
[0046] To perform the welding process described above, inside
surface 46 of closure housing 38 is compressed against lower end
flange 54 of outlet plate 40 by engaging the housing with a first
electrode 48, and applying pressure against the housing with the
first electrode in a first direction generally perpendicular to the
annular wall of the housing, while simultaneously engaging the
outlet plate with a second electrode 58, and applying pressure
against the outlet plate with the second electrode in a direction
perpendicular the first direction. The interference fit is formed
by applying sufficient pressure through first and second electrodes
48, 58 and moving at least one of the electrodes toward the other
electrode, while resistance welding together inside surface 46 of
closure housing 38 and lower end flange 54 of outlet plate 40, by
applying an electrical current between the electrodes for
resistance heating the housing and the outlet plate to a
temperature at which a metallurgical bond is formed between the
joining surfaces. Pressure and electrical current can be maintained
at a level and for a period of time sufficient to substantially
soften closure housing 38 and outlet plate 40 and allow a portion
the softened material of the housing to flow into the interference
juncture and weld the two parts together. In this manner, the
softened material can be forced to flow through a relatively
lengthy juncture, and the components to be joined can be maintained
at an optimum temperature for ensuring that a complete and high
quality weld is formed.
[0047] Further, in exemplary embodiments, it may be advantageous
apply pressure and a first level of electrical current flow through
closure housing 38 and outlet plate 40 for a first period of time,
for softening the housing by electrical resistance heating and
causing the softened housing to deform against the outlet plate,
under the pressure exerted by first and second electrodes 48, 58,
followed by the application of a second level of electrical
current, higher than the first level of current, for a second
period of time sufficient to at least partially melt the housing,
and form deformation resistance weld joint 41 between the housing
and the outlet plate.
[0048] It should be appreciated that for a joint of this type, the
ability to slide inside surface 46 of closure housing 38 along
lower end flange 54 of outlet plate 40 using DRW techniques
eliminates the close tolerance machining required in prior joining
methods, simplifies the form with which recess 56 can be provided,
and considerably simplifies, facilitates, and decreases the cost of
both construction and operation of the equipment used to make the
joint. For instance, in the exemplary embodiment described, the
point at which upper end flange 50 contacts outlet plate 40
controls the length of weld joint 41. Alternatively, stops for
first and second electrodes 48, 58 may be precisely designed for
even more precise control of the finished part length to make the
performance of the inflator more repeatable. For instance, in
exemplary embodiments, the transverse width of the annular wall of
closure housing 38 and the length of weld joint 41 can be
substantially equivalent to provide for increased weld strength. In
addition, the use of DRW techniques can provide for a reduced cycle
time, much improved weld strength and durability, and a decreased
the heat effect in the parent metals caused by weld heat by
providing the ability to heat treat the components in the weld
strength.
[0049] Referring again to FIG. 3, after closure housing 38 and
outlet plate 40 have been welded together as described above, a
wedge support member 60 and a movable wedge member 62 are disposed
between burst disk 44 and initiator 36. Support member 60 surrounds
a portion of initiator 36. In accordance with the present exemplary
embodiment, wedge member 62 is wedged between burst disk 44 and
support member 60. In addition, a projectile or pin 64 is received
in an opening 66 of support member 60. Pin 64 is also partially
received within an opening 68 in wedge member 62 to maintain the
pin in its supporting position between burst disk 44 and support
member 60.
[0050] In operation of the present exemplary embodiment, when
initiator 36 is activated, pin 64 will stroke or travel away from
support member 60 and through opening 68 in wedge member 62 to
release the wedge member from its supporting position. Pin 64 will
then make contact with, and thereby rupture, burst disk 44,
releasing the gas of first inflation chamber 32 through outlet
opening 42. In an alternative exemplary embodiment, pin 64 may be
used solely for releasing wedge member 62, in which case the
movement of the wedge member from its supporting position allows
burst disk 44 to rupture.
[0051] During this activation event, wedge member 62 travels
downwardly towards a screen member 70. Screen member 70 is
positioned to retain and/or prevent debris from exiting through an
outlet conduit 72 of the housing (in particular, debris from wedge
member 62 and portions of burst disk 44). In the present exemplary
embodiment, outlet conduit 72 is configured to provide fluid
communication between first inflation chamber 32 and an inflatable
cushion (not shown) after initiator 36 has been activated and burst
disk 44 has been removed from outlet opening 42.
[0052] In the present exemplary embodiment, initiator 36 is
angularly configured such that a surface of support member 60
locates or supports wedge member 62 between the support member and
a portion of burst disk 44 when the initiator is in an unactivated
state, as shown in FIG. 3. Furthermore, this arrangement allows
wedge member 62 to support burst disk 44 as it retains the
pressurized gas within the first inflation housing.
[0053] Wedge member 62 can further comprise another opening that is
configured to allow inflation gases to pass therethrough to allow
for the controlled release of the inflator gas under extreme
temperatures and pressures. It should, of course, be understood
that wedge member 62 may have various configurations, and exemplary
embodiments of the present invention are not limited to the
specific configurations of wedge member 62 as illustrated and
described in accordance the present exemplary embodiment.
[0054] In the present exemplary embodiment, as illustrated in FIG.
3, inflation housing 34 is integrally formed and includes a notch
79 that extends radially into the intersection of first and second
inflation chambers 32, 76. Second inflation chamber 76 comprises a
substantially smaller volume for holding a second amount of
inflation gas, which is to be provided into first inflation chamber
32 and, ultimately, through outlet opening 42 via an output orifice
81 disposed in divider plate 80, which is secured to notch 79 to
provide fluid communication between the first inflation chamber and
second inflation chamber 76. Divider plate 80 is formed with output
orifice 81 extending longitudinally into second inflation chamber
76 and an annularly shaped flange 83 extending generally
transversely to longitudinal axis 82.
[0055] In the present exemplary embodiment, divider plate 80 is
joined to notch 79 using DRW techniques, as illustrated in FIGS.
7-9, to form a deformation resistance weld joint 91. Inflation
housing 34 has an inside and an outside surface 84, 85 and defines
a longitudinal axis 82. Notch 79 is shaped as a depression that
extends radially inwardly within inflation housing 34 in a
generally transverse direction to longitudinal axis 82.
[0056] A lower surface 86 of annular flange 83 of divider plate 80
and an inner surface 87 of notch 79 proximate to second inflation
chamber 76 define the respective joining surfaces of weld joint 91.
The depression of notch 79 extends in a direction generally
parallel to the joining surfaces, both prior to and after
resistance welding divider plate 80 and notch 79 together.
[0057] With lower surface 86 of annular flange 83 and inner surface
87 of notch 79 on the side of second inflation chamber 76
contacting one another, as described above and depicted in FIGS. 7
and 8, weld joint 91 is formed by forcing notch 79 against annular
flange 83 and welding them together to the point shown in FIG. 9.
Notch 79 is compressed against annular flange 83 by engaging the
notch with a first electrode 88 and applying pressure against the
notch with the first electrode in a first direction generally
transverse to longitudinal axis 82, while simultaneously engaging
divider plate 80 with a second electrode 89, and applying pressure
against the divider plate with the second electrode in a generally
longitudinal direction perpendicular to the first direction. Notch
79 and annular flange 83 are abutted against one another by
applying sufficient pressure through first and second electrodes
88, 89, and moving at least one of the electrodes toward the other
electrode, while resistance welding together the notch and the
annular flange.
[0058] The resistance welding is accomplished by applying an
electrical current between the electrodes for resistance heating of
notch 79 and divider plate 80 to a temperature at which a
metallurgical bond is formed at between the respective joining
surfaces 86, 87 and within the depression of the notch. Pressure
and electrical current can be maintained at a level and for a
period of time sufficient to substantially soften notch 79 and
annular flange 83 and force the softened material into the
interference juncture between the two parts. In this manner, the
softened material can be forced to flow through a fairly long
juncture, and the components to be joined can be maintained at an
optimum temperature for ensuring that a complete and high quality
weld is formed. The depression of notch 79 can improve the quality
or the cleanliness of weld joint 91 by preventing weld flash from
reaching the inner diameter of the functioning area of the weld
joint.
[0059] Further, in exemplary embodiments, it may be advantageous
apply pressure and a first level of electrical current flow through
notch 79 and annular flange 83 for a first period of time, for
softening the annular flange by electrical resistance heating and
causing the softened flange to deform against the notch, under the
pressure exerted by first and second electrodes 88, 89, followed by
the application of a second level of electrical current, higher
than the first level of current, for a second period of time
sufficient to at least partially melt the annular flange, and form
deformation resistance weld joint 91 between the notch and the
flange.
[0060] By utilizing DRW techniques, the present exemplary
embodiment makes it unnecessary to use two separate chambers when
welding divider plate 80 and thus requires just a single weld joint
instead of multiple weld joints. That is, inflation housing 34 can
be integrally formed as described above and shown in FIGS. 7-9,
thereby reducing part costs and weight. It should further be
appreciated that, for a joint of this type, the ability to deform
the outer diameter of annular flange 83 within notch 79 using DRW
techniques eliminates the close tolerance machining required in
prior joining methods and considerably simplifies, facilitates, and
decreases the cost of both construction and operation of the
equipment used to make the joint. In the present exemplary
embodiments, stops for the electrodes may be precisely designed for
precise control of the finished part length to make the performance
of the inflator more repeatable. In addition, the use of DRW
techniques can provide for a reduced cycle time, much improved weld
strength and durability, and a decreased the heat effect in the
parent metals caused by weld heat by providing the ability to heat
treat the components in the weld strength.
[0061] In the exemplary embodiment illustrated in FIGS. 7-9,
divider plate 80 is formed with output orifice 81 extending
longitudinally into second inflation chamber 76 so that lower
surface 86 of annular flange 83 and inner surface 87 of notch 79 on
the side of the second inflation chamber contact one another at the
outset of the welding process. As illustrated in FIGS. 7 and 8,
such an arrangement is provided for by longitudinally extending
second electrode 89 within second inflation chamber 76 while
applying pressure against the notch with first electrode 88 in a
direction generally transverse to the second electrode. The
geometry of this exemplary embodiment can provide for better
mechanical strength of divider plate 80 in withstanding burst
pressure during initiation. In an alternative exemplary embodiment,
divider plate 80 can be formed with output orifice 81 extending
longitudinally into first inflation chamber 32 so that upper
surface 93 of annular flange 83 and inner surface 87 of notch 79
proximate to the first inflation chamber contact one another at the
outset of the welding process, as illustrated in FIG. 10. This
alternative geometry provides for improved contact between second
electrode 89 and divider plate 80 for improved electrode life in
manufacturing, and can be provided for by longitudinally extending
second electrode 89 within first inflation chamber 32 while
applying pressure against the notch with first electrode 88 in a
direction generally transverse to the second electrode.
[0062] Referring once again to FIG. 3, exemplary inflator 30 also
includes an end plate 90 disposed at an end of inflation housing 34
opposed to closure assembly 78. End plate 90 is configured with a
fill passageway 92 and a sealing means 94 secured therein after a
predetermined volume of inflation gas is supplied to first and
second inflation chambers 32, 76. In exemplary embodiments, fill
passageway 92 may be either closed or plugged in any fashion that
allows first inflation chamber 32 to be filled with a first
compressed volume of inflation gas and sealed. In non-limiting
exemplary embodiments, the gas stored in first and second inflation
chambers 32, 76 can comprise argon, helium, carbon dioxide,
nitrogen, or equivalents or mixtures thereof.
[0063] In exemplary embodiments, initiator 36 can be electrically
coupled to a sensing and diagnostic module (not shown) that is
configured to receive and interpret signals from a plurality of
vehicle sensors to determine whether an activation signal is to be
sent to the initiator. In accordance with the present exemplary
embodiment, initiator 36 is received within an initiator retainer
96 that may comprise a portion of closure housing 38. Initiator
retainer 96 helps position initiator 36 so that, upon receipt of
such an activation signal, initiator 36 will fire, causing pin 64
to stroke and rupture burst disk 44. Wedge member 62 will then be
free to move, thereby allowing the gas from first and second
inflation chambers 32, 76 to pass through outlet conduit 72.
[0064] As illustrated in FIG. 3, outlet opening 42 is substantially
larger than output orifice 81 in the present exemplary embodiment.
As a result, the inflation output from second inflation chamber 76
is at a substantially lower flow rate for an extended period of
time. This time period substantially longer than the period of time
for the inflation gases to flow out of first inflation chamber 32.
Therefore, in accordance with the present exemplary embodiment,
first inflation chamber 32 is used to provide an initial output for
initially deploying and inflating the inflatable cushion, while
second inflation chamber 76 is used to provide a secondary or
supplemental inflation output during and after the initial
inflation of the inflatable cushion. The output of second inflation
chamber 76 is configured to counteract the leakage of the inflation
gases from the inflatable cushion during initial deployment period.
In other words, to provide an extended period of inflation of the
inflatable cushion, first inflation chamber 32 is used to provide
an initial inflation output to deploy the inflatable cushion into a
desired inflated configuration, and thereafter any leakage of the
inflation gases used to inflate the inflatable cushion are
counteracted by the supplemental inflation output of second
inflation chamber 76 as smaller output orifice 81 allows the
supplemental inflation to be provided over a longer time period
than is typical for release of all the gases in a single stage
inflator.
[0065] During operation of inflator 30 of the present exemplary
embodiment, the external support member 60 for metal membrane or
burst disk 44 begins positioned at an angle to initiator 36, as
described above. Upon being activated, initiator 36 pressurizes a
chamber behind the pin that causes to the pin to stroke and release
wedge member 62. Thereafter, the pressure load on burst disk 44
creates a resultant force on wedge member 62 that pushes the wedge
member to the side away from the burst disk. Burst disk 44 then
ruptures, allowing gas to exit, and screen member 70 captures wedge
member 62.
[0066] Referring now to FIG. 11, an alternative exemplary
embodiment of an inflator manufactured in accordance with the
present invention is shown. In exemplary inflator 130, component
parts performing similar or analogous functions to those in the
exemplary embodiment described with regard to FIG. 3 above are
labeled in multiples of 100.
[0067] In the present exemplary embodiment, a metal membrane or
burst disk 144 and a wedge member 162 of a closure assembly 178 are
located on a center axis of inflator 130. Wedge member 162 is
attached directly to burst disk 144 and also contacts a narrow tip
161 of an initiator support cap 160 off-center on a parallel axis.
In this embodiment, support cap 160 is located over initiator 136.
During activation of initiator 136, a chamber 159 behind support
cap 160 is pressurized, causing the support cap to stroke and
contact wedge member 162, thereby imparting axial and radial forces
on the wedge member. The component forces of support cap 160
operate to move wedge member 162 so that burst disk 144 is
unsupported and accordingly ruptures to allow the gas to exit.
Thereafter, a screen member 170 captures burst disk 144. In
exemplary embodiments, wedge member 162 may be fixedly secured to
burst disk 144 or merely supported on the burst disk by support cap
160.
[0068] In accordance with the present exemplary embodiment, closure
housing 138 is joined to outlet plate 140 using DRW techniques in
the same manner as the analogous parts of the exemplary embodiment
of FIG. 3. Additionally, divider plate 180 is joined to notch 179
using DRW techniques in the same manner as the analogous parts of
the exemplary embodiment of FIG. 3. Exemplary embodiments of these
methods are described above and illustrated in FIGS. 4-10.
[0069] In the present exemplary embodiment, support cap 160 and
wedge member 162 are disposed between burst disk 144 and initiator
136. Support cap 160 defines chamber 159 to be in fluid
communication with initiator 136. Wedge member 162, which is
located adjacent to and wedged between burst disk 144 and support
cap 160, has an outer periphery or diameter that is less than the
outer periphery or diameter of the burst disk. As illustrated in
FIG. 11, tip 161 of support cap 160 is disposed off axis, but
parallel, to a tip 163 of wedge member 162. Of course, other
configurations (such as, for example, non-parallel tips 161, 163)
are contemplated in alternative exemplary embodiments.
[0070] During operation of the present exemplary embodiment, when
initiator 136 is activated, the pressure in chamber 159 behind
support cap 160 increases to cause the support cap to stroke away
from the initiator. This causes tip 161 of support cap 160 to act
on tip 163 to dislodge wedge member 162, thereby causing the wedge
member to travel away from burst disk 144. Thereafter, burst disk
144, no longer supported by wedge member 162, will be allowed to
rupture so that the gas of first inflation chamber 148 releases
through outlet opening 156.
[0071] While the invention has thus far been described above with
reference to specific exemplary embodiments of a side airbag
inflator comprising a first chamber and a second chamber that are
longitudinally aligned, the broader practice of the invention is
not necessarily so limited. As such, the present invention is not
intended to be limited to the specific exemplary embodiments and
configurations illustrated in the Figures and described herein, as
they are considered ancillary to the present invention.
[0072] Moreover, exemplary embodiments of inflators in accordance
with the present invention are contemplated for use with numerous
other airbag modules. For instance, in addition to side airbag
modules, the inflator may be configured as a component of a driver
side airbag module or a passenger side airbag module.
[0073] Reference will now be made to FIG. 12, in which the interior
of an exemplary vehicle 210 for transporting an operator 212 and a
passenger 214 is illustrated. Vehicle 210 may include a driver side
airbag module 220 mounted within the steering wheel 218 for
protection of vehicle operator 212. Vehicle 210 can also include a
passenger side airbag module 216 mounted within the dash panel in
substantially opposing relation to vehicle passenger 214.
Activation of airbag modules 216, 220 typically takes place upon
the occurrence and measurement of predetermined vehicle conditions
such as deceleration at a rate exceeding a predetermined value.
[0074] Referring now to FIG. 13, an exemplary embodiment of an
assembly for driver side airbag module 220 is illustrated. Airbag
module 220 is suitably mounted to a central hub or armature of a
steering wheel. Typically, some form of mounting mechanism will be
provided to mount the airbag module assembly components to each
other and to the steering wheel.
[0075] Airbag module 220 includes a cover plate 222, an inflatable
airbag cushion 224, an annular cushion ring 226, an annular cover
retainer 228, an inflator 230, and an annular retaining plate or
pad retainer plate 232. Typically, cushion ring 226 is formed from
metal and secured to one side of an inflator opening of airbag
cushion 224, while cover retainer 228, which is also formed from
metal, is disposed on the other side of the inflator opening. Thus,
a periphery of the inflator opening of airbag cushion 224 is
disposed between cushion ring 226 and cover retainer 228, and the
two are drawn together by tightening of a plurality of nuts 238
about a plurality of threaded bolts 234 passing through openings in
the cushion ring, the periphery of the inflation opening of the
inflatable cushion, and the cover retainer. In other exemplary
configurations, cushion ring 226 can be secured to cover retainer
228 by a plurality of bolts 234 passing through openings in the
cushion ring, the cover retainer, and retaining plate 232.
Thereafter, plurality of nuts 238 are disposed about threaded bolts
234 to secure the assembly together.
[0076] Cushion ring 226 is typically used for mounting/attaching
airbag cushion 224 to the airbag module. In other words, cushion
ring 226 secures the opening of airbag cushion 224 about a portion
of inflator 230 as well as retaining plate 232, which is fixedly
secured to the vehicle. In exemplary airbag module assemblies,
cushion ring 226 can be a separate metal component that is riveted
or bolted together with other adjoining components in the airbag
module, such as cover plate 222, so as to merely pinch/squeeze the
airbag cushion between the adjoining components. Cover plate 222 is
used to secure the airbag module's cover (not shown) in the final
assembly.
[0077] As illustrated in FIG. 13, airbag module 220 includes an
inflator 230 manufactured in accordance with an exemplary
embodiment of the present invention. Inflator 230 is configured to
generate inflator gas upon the sensing of predetermined vehicle
conditions (for example, rapid deceleration) to inflate airbag
cushion 224. In exemplary embodiments, inflator 230 can be of any
conventional construction for generating inflator gas to inflate
the airbag cushion 224, such as a single stage inflator. Inflator
230 has a generally cylindrical housing portion 242 secured to a
generally circular base plate 236 that suitably engages with cover
retainer 228 and cushion ring 226. A plurality of vent ports 240
are formed in and extend around housing 242 into inflator 230 in a
radial manner. Base plate 236 also includes an opening 244 to
permit an initiator to extend into inflator 230. It should be
understood that the number and dimension of vent ports 240 may be
varied according to the precise application and configuration of
inflator 230 in particular exemplary embodiments.
[0078] In exemplary embodiments of the present invention, housing
portion 242 and base plate 236 of inflator 230 are secured to one
another using DRW techniques, as illustrated in FIGS. 12 and 13, to
form deformation resistance weld joint 278. Housing 242 defines a
longitudinal axis 246 and an inside and an outside surface 248, 250
of inflator 230. Base plate 236 extends across a lower end 252 of
housing 242 in a generally transverse direction to longitudinal
axis 246.
[0079] To define the joining surfaces of weld joint 278, lower end
252 of housing 242 is formed with two angled chamfers 258, 260 on
inside and outside surfaces 248, 250 respectively, and an upper
surface 254 of base plate 236 is formed with an annular groove 262
that is generally concentric with and of a similar diameter to the
lower end of the housing. This configuration of the joining
surfaces is intended to produce two concentric deformation
resistance weld interfaces 279, 280 at the angled chamfers 258, 260
that are welded at the same time, as described below.
[0080] As best seen in FIG. 14, at the outset of the welding
process, lower end 252 of housing 242 is circumferentially aligned
with annular groove 262 of base plate 236. The transverse width of
housing 242, however, is greater than the transverse width of
annular groove 262 at the outset of the welding process. This
differential provides for diametrical interference in the mating
parts to permit deformation and sliding of the mating surfaces
along each other during the weld process.
[0081] With lower end 252 of housing 242 is longitudinally aligned
with annular groove 262 of base plate 236, a weld joint 278 can be
formed between housing portion 242 and base plate 236. In the
present exemplary embodiment, the welded joint is formed by sliding
lower end 252 of housing 242 into annular groove 262 while forcing
the two components against each other under sufficient pressure to
form an interference fit. As shown in FIG. 15, the welding process
is complete at a point at which lower end 252 of housing 242
engages the transverse section of annular groove 262.
[0082] To perform the welding process described above, lower end
252 of housing 242 is compressed into annular groove 262 by
engaging the housing with a first electrode 264, and applying
pressure against the housing with the first electrode in a first
direction generally perpendicular to the annular housing of
inflator 230, while simultaneously engaging base plate 236 with a
second electrode 266, and applying pressure against the outlet
plate with the second electrode in a direction perpendicular the
first direction. In the present exemplary embodiment, second
electrode 266 includes a direct water-cooling mechanism 272 to
provide for less heat effect in the area of base plate 236 that is
not part of weld joint 278. Second electrode 266 also comprises a
clearance aperture 268 to receive an initiator 270 where the
initiator has been received in opening 244 of base plate 236 prior
to welding, as illustrated in FIG. 15. In alternative exemplary
embodiments, initiator 270 need not be installed in opening 244
until after welding.
[0083] The interference fit is formed by applying sufficient
pressure through first and second electrodes 264, 266 and moving at
least one of the electrodes toward the other electrode, while
resistance welding together lower end 252 of housing 242 and
annular groove 262 by applying an electrical current between the
electrodes for resistance heating the housing and the outlet plate
to a temperature at which a metallurgical bond is formed between
the joining surfaces. Pressure and electrical current can be
maintained at a level and for a period of time sufficient to
substantially soften housing 242 and base plate 236 and force the
softened material into the interference juncture between the two
parts. In this manner, the softened material can be forced to flow
through a fairly long juncture, and the components to be joined can
be maintained at an optimum temperature for ensuring that a
complete and high quality weld is formed.
[0084] Further, in exemplary embodiments, it may be advantageous
apply pressure and a first level of electrical current flow through
housing 242 and base plate 236 for a first period of time, for
softening the housing by electrical resistance heating and causing
the softened housing to deform against the base plate, under the
pressure exerted by first and second electrodes 264, 266, followed
by the application of a second level of electrical current, higher
than the first level of current, for a second period of time
sufficient to at least partially melt the housing, and form
deformation resistance weld joint 278 between the housing and the
base plate.
[0085] It should be appreciated that for a joint of this type, the
ability to slide lower end 252 of housing 242 into annular groove
262 using DRW techniques eliminates the close tolerance machining
required in prior joining methods, simplifies the form with which
the annular groove can be provided, and considerably simplifies,
facilitates, and decreases the cost of both construction and
operation of the equipment used to make the joint. For instance, as
illustrated in FIG. 15, the welding mechanism can be provided with
an insulation plate 274 disposed adjacent to an upper surface 276
of inflator 230 to control the proximity of base plate 236 to first
electrode 264 during welding. Alternatively, stops for the
electrodes may be precisely designed to provide for more precise
control of the finished part length and thereby make the
performance of the inflator more repeatable. Moreover, in
alternative exemplary embodiments, annular groove 262 of base plate
236 may instead be provided as an interstitial annular groove that
extends to the periphery of upper surface 254 of the base plate, as
illustrated in FIG. 16, so that only a single deformation
resistance weld interface 281 is formed between a single angled
chamfer 258 on inside surface 248 of housing 242 and upper surface
254 of the base plate. This configuration can provide for weld
joints of a single-sided geometry that may be adequately strong for
the intended service, while permitting for improved contact between
the electrodes and outside surfaces of the mating components. In
other alternative exemplary embodiments, angled chamfers 258, 260
and/or annular groove 262 having unequal geometries so that two
unequal, concentric weld interfaces. In addition, the use of DRW
techniques can provide for a reduced cycle time, much improved weld
strength and durability, and a decreased the heat effect in the
parent metals caused by weld heat by providing the ability to heat
treat the components in the weld strength.
[0086] Referring back to FIG. 13, in response to a sudden
deceleration of the vehicle, a controller such as a sensing and
actuating system (not shown) provides an ignition signal to the
initiator to initiate deployment inflation of the airbag cushion
224. Upon actuation of the initiator in response to the ignition
signal, inflator 230 discharges an appropriate volume of gas from
vent ports 240 into airbag cushion 224.
[0087] Exemplary inflator 230 is described above and illustrated in
FIG. 13 as a component of a driver side airbag module for
installation in a driver side of a vehicle to protect the driver
thereof. It should be recognized, however, that inflator 230 can be
a component of other passive restraints in alternative exemplary
embodiments. For instance, inflator 230 can be a component of a
passenger side airbag module that can be mounted within a vehicle's
dash panel in exemplary embodiments, such as airbag module 216
shown in FIG. 12, for protection of an occupant in the vehicle's
passenger seat.
[0088] It should be recognized that the present invention is not
intended to be limited to the specific configurations provided in
the exemplary embodiments described above and illustrated in the
drawings, as they are considered ancillary to the present
invention. That is, the scope of the present invention encompasses
many other vehicle configurations and inflator arrangements in
alternative embodiments. For example, the vehicle may include three
rows of seats such as, but not limited to, sports utility vehicles,
station wagons, and vans or minivans. Alternatively, the vehicle
may comprise only a single row of seats such as, but not limited
to, sports coups. Therefore, exemplary embodiments of an airbag
inflator in accordance with the present invention may be easily
modified to accommodate all types of vehicles and airbag module
assemblies in several different types of configurations.
[0089] While the invention has been described with reference to an
exemplary embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
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