Simplified driver side air bag assembly

An air bag module (20) comprising: a housing (22) having a first opening (102) within a first housing portion (100), a retaining member (24) having a second opening (52) and at least one pair of opposed open faced ramps (40a,b), an air bag (26) having an inflatable cushion portion (80) and a neck portion (82), the neck portion is located between the housing and retaining member (24), a cover (30) to protect the air bag, the cover being opened by the air bag upon inflation thereof, and an inflator (28) received within the first opening from a bottom of the first housing portion (100) and into the second opening (52), the inflator including a flange (36); wherein with an edge of the inflator flange located proximate a respective open face of a ramp and the inflator rotated, the flange engages the ramps and is drawn toward the retaining member thereby sandwiching the housing and air bag therebetween.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates to a driver side air bag system and more 
particularly one that clamps a housing, retainer member, air bag and 
inflator together without the use of separate fasteners. 
It is an object of the present invention to provide an improved air bag 
system that is easy to manufacture and assemble. It is a further object of 
the present invention to provide an air bag module in which various parts 
of the module are interconnected. 
Accordingly the invention comprises an air bag module comprising: a housing 
having a first opening within a first housing portion, a retaining member 
having a second opening and at least one pair of opposed open faced ramps, 
an air bag having an inflatable cushion portion and a neck portion, the 
neck portion is located between the housing and retaining member, a cover 
protects the air bag, the cover being opened by the air bag upon inflation 
thereof, and an inflator received within the first opening from a bottom 
of the first housing portion and into the second opening, the inflator 
including a flange; wherein with an edge of the inflator flange located 
proximate a respective open or receiving face of a ramp and the inflator 
rotated, the flange engages the ramps and is drawn toward the retaining 
member thereby sandwiching the housing and air bag therebetween. In one 
embodiment the flange is segmented and also includes a ramped portion to 
engage the ramps on the retaining member. In another embodiment the ramps 
are fabricated on an elevated portion of the retaining member. In this 
embodiment the inflator flange is generally flat. 
It is a further object of the present invention to reduce the number of 
components required to manufacture an airbag module and thereby reduce 
cost. 
Many other objects and purposes of the invention will be clear from the 
following detailed description of the drawings.

DETAILED DESCRIPTION OF THE DRAWINGS 
FIG. 1 is an assembly view showing the major components of an air bag 
module 20. These components comprise a housing 22, a retaining member 24, 
an air bag or cushion 26, an inflator 28 and a cover 30. 
Inflator 28, also shown in FIG. 2, comprises a cylindrical body 32 having a 
plurality of exit ports 34 situated thereabout. A mounting flange 
generally shown by numeral 36, in the illustrated embodiment, extends from 
the midpoint of a side wall 38 of the inflator 28. It should be 
appreciated that the flange can extend from any portion of the inflator. 
The flange 36 is segmented and forms a plurality of notches between 
various segments of the flange 36. More particularly, the flange 36 
includes two flat opposing segments 36a and 36b which extend radially 
outward. The flange 36 additionally includes two additional opposing 
segments 36c and 36d. Each flange segment 36a-36d includes a respective 
small notch 38a-d which is capable of receiving a bent-over tab extending 
from the retainer member. The flange segments 36c and 36d respectively 
include a flat radially extending portion 37 and upwardly extending ramp 
portions (also referred to as a ramp) 40a and 40b respectively. As can be 
seen, the ramp portions 40a and 40b extend smoothly away from the 
corresponding radially extending portion 37 of the flange segments 36c and 
36d. The leading edge of each ramp portion is shown by numeral 39 and 
defines an open face or receiving portion. The angle of the ramp, relative 
to the flat flange segments, is chosen so that it allows interaction with 
the ramp located on the mating component to provide positive, smooth and 
effective clamping. In addition, the ramps 40a and 40b in the illustrated 
embodiment are manufactured by stamping a blank that does not contain the 
flange, and then forming the ramps and notches. As is known in the art, 
the inflator 28 may take any of a number of forms such as a cold stored 
gas inflator, a hybrid inflator or a solid propellant inflator. In each 
case, upon receipt of a control signal indicative of a crash, inflation 
gas is produced or released to inflate a closely spaced air bag such as 
air bag 26. 
As will be seen from the discussion below, the inflator is inserted from an 
underneath side of the housing 22 through a hole and twisted in place. 
This twisting action positively engages the retainer member 24 and 
sandwiches the air bag 26 between the retainer member 24 and the housing 
22 while securing the inflator 28 to the retaining member which may 
comprise a ring or plate 24. 
Reference is briefly made to FIGS. 3a and 3b, as well as FIG. 1. The 
retaining member 24 comprises a plate portion 50 having a central aperture 
52. Extending outwardly and upwardly from the plate 52 are optional side 
walls 54. As can be seen, if used, the side walls 54 give the retaining 
ring 24 a cup-like appearance. The retaining ring can take many shapes 
such as square, rectangular, or circular. The retaining ring 24 is 
typically made of metal or plastic and formed, proximate the central 
opening, with a plurality of receiving tabs. The tabs can be added to the 
plate or formed as an integral part thereon. Tabs 56a and 56b are 
positioned opposite each other and formed as upraised, integral portions 
of the plate 50. These tabs are L-shaped and include a radially, inwardly 
extending portion 58 and a vertically extending standoff or wall 60. As 
can be seen from the various views, the inwardly extending portions 58 are 
spaced parallel to the plane of the plate 50. The retaining member or ring 
24 additionally includes a plurality of opposing ramped tabs 62a and 62b. 
Each of the ramped tabs includes a ramped engagement surface 64, a side 
wall 66 and a leading edge 65 defining an open face, mouth or receiving 
end. The ramped tabs extend below the generally flat undersurface of the 
plate 50 as shown in FIG. 3a. Central aperture 52, mentioned above, 
includes circular portion 70, and two opposing notches or openings 72a and 
72b which are formed when the tabs 58a and 58b are separated from the 
plate 50. The opening 70 includes two larger dimension slots, notches or 
openings 74a and 74b which are positioned respectively under and adjacent 
the ramped tabs 62a and 62b. The retaining member 22 further includes a 
plurality of integrally formed, outwardly extending retention tabs 76a, 
76b, 76c and 76d. 
Reference is briefly made to FIG. 4 which diagrammatically illustrates the 
various features of an air bag 26. As is known in the art, an air bag is 
manufactured by one or more fabric or plastic film sections forming a 
one-piece or multi-piece construction. The bag can also be woven, knitted, 
blown, vacuum molded, etc. When formed the air bag comprises an inflatable 
cushion portion 80 and a neck portion 82. The neck portion 82 is 
positioned proximate the inflator 28. This neck portion is often 
reinforced by a number of layers of material 84 which function as a 
reinforcement and heat shield to protect the other surrounding portions of 
the air bag 26. The neck portion 82 of the present invention, including 
those other layers of material 84, includes a central opening 86 and a 
plurality of smaller openings 88, also shown in FIG. 1. Reference is again 
made to FIG. 1 which shows the neck portion 82 of the air bag. The 
additional heat shielding layers 84 and the cushion portion 80 have been 
removed for the purpose of clarity. As can be seen, the opening 86 is 
shaped similar to the opening 52 having a central portion 90 and two 
extending notches 92a and 92b which are of similar size to the openings 
72a and 72b in the plate 50. The opening 86 further includes two optional 
notches 94a and 94b which are of similar size to notches 74a and 74b of 
the plate 50. During assembly of the air bag module 20 the retaining 
member 24 is inserted within the center opening 86 and manipulated such 
that the retention tabs 76a-76d extend through one of the smaller openings 
88 with the various complementary features such as notches 74a and 92a and 
74b and 92b, etc. of the holes 52 and 58 in alignment. 
Reference is again made to FIG. 1 and more particularly to the housing 22 
and cover 30. The major purpose of the housing 22 is to provide a backing 
plate upon which the air bag 26 is positively secured to avoid inflation 
gas leaking therefrom and to provide a reaction surface during deployment. 
In its simplest form the housing 22 may comprise a base plate 100 having a 
central opening 102 shaped similar to the opening 86 in the air bag. 
However, in the embodiment shown, the housing 24 includes upraised walls 
112 which extend downwardly from the plate 100. The opening 102 includes 
larger extending notches or portions 104a and 104b and optional extending 
smaller notches or portions 106a and 106b. Notches 106a,b may be 
extensions of opening 102 or separated therefrom by a portion of the plate 
100. The plate 100 additionally includes a plurality of smaller tab 
receiving openings 108. These downwardly extending walls contact the inner 
portions of the cover. The housing and cover are then secured together by 
some means such as rivets. The precise way the cover and the housing 
cooperate is not particularly relevant to the present invention albeit 
that the cover is secured to the housing in a manner so that it will not 
be dislodged from the housing during inflation of the air bag. The housing 
22 or plate 100 may include a plurality of extending mounting fasteners 
such as the threaded inserts 120, studs or other features which are used 
to mount the module 20 to a cooperating structure within the vehicle. 
Obviously, if the module 20 were used as a driver side module, the 
fasteners 120 such as threaded studs, would be secured into a structural 
component within the steering wheel. The fasteners 120 could optionally 
extend from the retaining member 24 through cooperating openings in the 
neck 82 of the air bag 26 (not shown) and through other openings (not 
shown) in the plate 100. 
The module cover 30 is also shown in FIG. 1. This cover 30 is only 
diagrammatically illustrated as many different configurations of the cover 
can be used with the present invention. As is known in the art, the 
purpose of the cover is to provide a decorative fascia which encloses and 
protects the air bag. A typical cover will include a top 130 which is 
designed with a visible or invisible stress point, often referred to as a 
tear seam 132. The cover includes extending sides 134 which are attached 
to the housing 22 (or plate 100) at 112. In the embodiment illustrated, 
the cover is of a generally square or rectangular configuration, 
conforming to the shape of the housing. 
As can be appreciated from the above, the inflator 28 is inserted within 
opening 102 from the underside of the housing 22. This feature permits the 
other portions of the module, i.e., the cover 30, retaining member 24, air 
bag 26 and housing 22 to be assembled prior to insertion of the inflator 
28 therein. 
The assembly and operation of this embodiment of the invention is as 
follows. As mentioned above, the retaining member 24 is inserted within 
opening 86 of the air bag 20 and manipulated so that openings 52 and 90 
are in conformity and the tabs 76a-d extend through one of the openings 88 
in the air bag 26. The tabs 76a-d are then fit through a corresponding one 
of the openings 108 in the housing plate 100. Two of the tabs such as 76a 
and 76b can be bent outwardly to partially lock the retaining member 24, 
air bag 26 and housing 22 together. Subsequently, the cushion 80 of the 
air bag 26 is folded into a compact configuration and positioned about 
opening 102 of the housing plate 100. Thereafter the cover 30 is secured 
to the housing 22. 
Subsequently, the inflator 28 is secured to the above-assembled portions of 
the module 20. Reference is briefly made to FIG. 5 which illustrates a top 
isometric view showing the inflator positioned upon the plate 100 of the 
housing 22 and below the retainer member 24 with the leading edges of each 
of the ramped flanges 40a and 40b positioned at the respective opening or 
mouth 65 of the ramped tabs 62a and 62b. For the purposes of clarity, the 
cover has been removed from FIGS. 5 and 6. As can be appreciated, the 
forward tip or leading edge 39 of the respective ramp 40a and 40b extends 
above the opening 74a,b of the respective ramped tab 62a and 62b. 
Subsequently the inflator is rotated in a counterclockwise direction as 
viewed from the inside of the retaining member (as also illustrated in 
FIG. 6.) This action generates a clamp-fit between the ramped flanges 40a 
and 40b and the corresponding ramped portion 64 of the ramped tabs 62a and 
62b respectively. Further, if used, this rotation also rotates the 
radially extending flanges 36a and 36b of the inflator 28 under a 
corresponding one of the retention tabs 56a and 56b. 
As can be appreciated, the rotation of the inflator 28 clamps the retaining 
member 24 to the inflator, thereby sandwiching the air bag 26 against the 
housing plate loo. The orientation of the various parts of the flange 36 
and the retaining tabs 76a-76b can also be seen in FIG. 7. As mentioned 
above, some of these tabs 76a and 76b can be bent outwardly (see arrow 77) 
to initially retain the retaining member 24 to the housing 22 prior to 
introduction of the inflator. Other initial retaining or position 
techniques, used in manufacturing, can also be used. The remaining 
retention tabs 76c and 76d are thereafter bent inwardly (see arrow 79) and 
received within one of the notches such as 36a and/or 36b of the flange 
segments of the inflator 28. As can be appreciated, this arrangement of 
tab and notch provides an anti-rotation feature preventing the inflator 
from rotating outwardly. 
The operation of the module follows that of a classic air bag module. Upon 
receipt of a crash signal to the inflator, the propellant or gas stored 
within the inflator is activated, thereby producing or releasing a 
quantity of inflation gas which is communicated through inflator ports 34 
to inflate the air bag 26. The inflating air bag bears against the 
underside of the top 130 of the cover 30 causing the tear seam or tear 
seams 132 to rip apart, thereby providing an opening through which the air 
bag may continue to deploy to protect the occupant. As the cushion deploys 
an opposite reaction force is exerted rearwardly against the L-shaped 
bracket and the ramped surfaces which secure the inflator in the retaining 
member and housing. In addition, the retaining tabs 76a-76d serve to keep 
the cushion in position during the deployment. 
Reference is made to FIG. 8 which illustrates an alternate embodiment of 
the invention where similar components are identified by the same 
numerals. More specifically, FIG. 8 shows an alternate driver air bag 
module 20 comprising a retaining member 24, cushion 26, housing 22 and 
inflator 28. In this embodiment, the ramped flanges on the inflator 28 of 
FIG. 1 have been removed and an alternate set of ramps placed in the 
retaining member 24. The retaining member 24 comprises a plate portion 50 
with an optional upwardly extending peripheral wall 54. The center opening 
52 is generally circular in shape. The plate material 50 which previously 
was found in the center of the plate is bent over into two pairs of 
extending flanges 150a and b and 150c and d. Each of the flanges 150a-d 
includes upraised leg 152 and an inward, radially extending arm 154. The 
height and depth of the legs 152 and arms 154 will vary with the height of 
the inflator 28. Each of the flanges 150a-d includes an inwardly extending 
ramped tab 160 which is formed by stamping and bending inwardly a portion 
of each leg 152. As can be seen from FIG. 9 each tab 160 is angled 
relative to a corresponding arm 154. 
The cushion 26 of this second embodiment is identical to the cushion 
discussed above with the exception that the central opening 86 is 
generally circular to conform with the circular shape of opening 52. The 
neck 82 of the air bag 26 includes the plurality of tab receiving openings 
88. As can be seen from FIGS. 8 and 9, this retaining member 24 
additionally includes the plurality of bent-over retaining flanges 
76a-76d. The housing 22 may comprise a plate 50 or, alternatively, may be 
formed as an open sided container or box with the inclusion of the 
peripheral wall 112 (as used in FIG. 1). The plate 100 similarly includes 
the plurality of tab receiving openings 108. The inflator 28, which is 
also shown in FIG. 10, is cylindrically shaped and includes a circular, 
radially extending flange 36 which extends from the side wall of the 
inflator. The location of this flange is determined from the parameters of 
the module components. Secured to the top 170 of the inflator 28, such as 
by welding, is a mounting plate or flange 180. The mounting plate could be 
integrally formed as part of the body of the inflator. The mounting plate 
includes four radially shaped corners 182. Each side 184 of the plate 180 
is flat and further includes an inwardly directed notch 186. The diameter 
of the mounting plate 180, that is the distance measured diagonally 
between opposing, radially shaped corners 182, is slightly smaller than 
the diameter of the opening 52 of the retaining member 24. 
During assembly, the retaining member 24 is slid through the center opening 
86 in the air bag 26 and manipulated so that the tabs 76a-d extend through 
a respective tab receiving opening 88 in the air bag. Subsequently, the 
tabs 76a-d are received through one of the tab receiving openings 108 in 
plate 100. One or more of these tabs, such as tab 76a, can be bent over to 
temporarily secure the retainer 24, air bag 26 and plate 100 (or housing 
22) together as described above. Thereafter, the air bag 26 can be folded, 
a cover such as 30 secured to the housing 22 and the inflator 28 inserted 
and locked in place. Alternatively, the inflator may first be inserted 
within the retaining member and the air bag can later be folded with the 
cover and then placed upon the air bag. 
As with the earlier embodiment, the inflator 28 is inserted from the bottom 
side of the housing 22 into the retaining member 24. The inflator is 
oriented, prior to insertion within the housing 22, such that each notch 
186 lies below a corresponding, inwardly extending ramped tab 160. In this 
manner, as the inflator 28 is inserted through the housing and through and 
into the retaining member 24, the plate 180 will pass across the ramped 
tabs 160 as these tabs 160 are received in and through each corresponding 
notch 186. The inflator is inserted within the retaining member 24 until 
the top of the. plate 180 butts against the bottom of each of the radial 
arms 154. This relationship is shown in FIG. 11. For clarity, the cover 
has been removed. 
The inflator 28 is rotated in a counterclockwise manner (see arrow 190 of 
FIG. 11). As the inflator 28 including its plate 180 rotate, a leading 
edge 184 of each of the curved corners 182 enters into the wide mouth 
portion 65 of the ramped tab 160. Subsequent rotation of the inflator 28 
and plate 180 causes the corners 182 to be trapped between the ramped tabs 
160 and the radial arms 154 also drawing the inflator flange 36 inwardly 
and clamping the cushion 26 and plate 100 (of housing 22) together. 
Clockwise rotation could be included by changing the direction of the 
ramps. 
Many changes and modifications in the above-described embodiment of the 
invention can, of course, be carried out without departing from the scope 
thereof. Accordingly, that scope is intended to be limited only by the 
scope of the appended claims.