Vehicle occupant protection apparatus

A vehicle occupant protection apparatus (10) includes a reaction structure (16), an inflator (14) for inflating a vehicle occupant protection device (12), an initiator (102) for initiating a flow of inflation fluid from the inflator (14), and a tubular connector (104) containing the initiator (102). The connector (104) engages the inflator (14), and extends through an aperture (176) in the reaction structure (16). A fastener (182) engages the connector (104) to fasten the connector (104), the initiator (102) and the inflator (14) to the reaction structure (16). In a preferred embodiment, the apparatus (10) further includes a diffuser (150) with a circular end wall (152) and a cylindrical side wall (154) projecting axially from the end wall (152). The side wall (154) of the diffuser (150) has fluid flow openings (156), and has an annular edge portion (158) crimped against a rim structure (160) on the inflator (14). A mounting stud (162) projects radially from the diffuser (150) and extends through an aperture (178) in the reaction structure (16). Another fastener (180) engages the mounting stud (182) to fasten the diffuser (150) and the inflator (14) to the reaction structure (16).

FIELD OF THE INVENTION 
The present invention relates to an apparatus for protecting an occupant of 
a vehicle, and particularly relates to an apparatus including an 
inflatable vehicle occupant protection device. 
BACKGROUND OF THE INVENTION 
An inflatable vehicle occupant protection device, such as an air bag, is 
part of an apparatus which further includes a crash sensor and an 
inflator. The crash sensor senses vehicle conditions that indicate the 
occurrence of a crash. When the crash sensor senses a crash-indicating 
condition of at least a predetermined threshold level, the inflator is 
actuated. The inflator then emits inflation fluid which inflates the air 
bag into the vehicle occupant compartment to help protect an occupant of 
the vehicle from a forceful impact with parts of the vehicle. 
An air bag and an inflator are typically assembled together as parts of an 
air bag module which is separate from the crash sensor. The air bag module 
is located in the vehicle adjacent to the vehicle occupant compartment. 
For example, a driver's side air bag module may be located on the vehicle 
steering column. A passenger side air bag module may be located in the 
vehicle instrument panel. In addition to the air bag and the inflator, an 
air bag module includes a reaction structure which supports the inflator 
and the other parts of the module in the vehicle. 
SUMMARY OF THE INVENTION 
In accordance with one aspect of the present invention, an apparatus 
comprises a reaction structure, an inflator and an initiator. The inflator 
comprises a source of fluid for inflating a vehicle occupant protection 
device. The initiator, when actuated, initiates a flow of fluid from the 
inflator. The apparatus further comprises a tubular connector which 
contains the initiator. The connector engages the inflator, and extends 
through an aperture in the reaction structure. A fastener engages the 
connector to fasten the connector, the initiator and the inflator to the 
reaction structure. 
In accordance with another aspect of the present invention, an apparatus 
comprises a reaction structure, an inflator and a diffuser. The inflator 
has a rupturable closure part and an annular rim structure surrounding the 
closure part. The diffuser has a circular end wall and a cylindrical side 
wall projecting axially from the end wall. The side wall of the diffuser 
has a plurality of fluid flow openings, and has an annular edge portion 
crimped against the rim structure on the inflator. The diffuser further 
has a radially projecting mounting stud extending through an aperture in 
the reaction structure. A fastener engages the mounting stud to fasten the 
diffuser and the inflator to the reaction structure.

DESCRIPTION OF A PREFERRED EMBODIMENT 
An apparatus 10 comprising a preferred embodiment of the present invention 
is shown in FIG. 1. The apparatus 10 includes a particular type of 
inflatable vehicle occupant protection device 12 (shown schematically) 
which is commonly referred to as an air bag. The apparatus 10 further 
includes an inflator 14 for inflating the air bag 12. The inflator 14 and 
the air bag 12 are supported on a reaction structure 16. In the preferred 
embodiment of the present invention, the reaction structure 16 is a base 
plate for supporting the inflator 14 and the air bag 12 on a vehicle 
steering column (not shown) in a known manner. The base plate 16, the 
inflator 14 and the air bag 12 are preferably parts of an air bag module 
which, as known in the art, includes other parts (not shown) such as an 
air bag cover and a horn switch. Such other parts of the module can be 
connected to the base plate 16 in any suitable manner known in the art. 
The inflator 14 comprises a container 20 storing pressurized inflation 
fluid for inflating the air bag 12. As shown in greater detail in FIGS. 2 
and 3, the container 20 has a generally cylindrical shape defined by a 
tubular side wall 22, a first circular end wall 24, and a second circular 
end wall 26, each of which is centered on a longitudinal axis 27. 
The side wall 22 and the first end wall 24 of the container 20 are portions 
of a single, continuous piece of metal such as steel or aluminum. A 
circular outlet opening 28 extends through the center of the first end 
wall 24. A rupturable closure disk 30 extends across the outlet opening 
28, and is fixed and sealed to the first end wall 24 by a 
circumferentially extending weld 32. The closure disk 30 may have any 
suitable structure known in the art, but preferably has a plurality of 
radially extending score lines 34. The score lines 34 delineate a 
corresponding plurality of petal-shaped sections 36 of the closure disk 30 
which separate and deflect axially outward when the closure disk 30 is 
ruptured. 
The second end wall 26 of the container 20 has a circular base portion 38 
with an annular end surface 40. The end surface 40 abuts an opposed 
annular end surface 42 of the side wall 22. A friction weld 44 fixes and 
seals the second end wall 26 and the side wall 22 together at the abutting 
end surfaces 40 and 42 circumferentially entirely around the axis 27. The 
three walls 22, 24 and 26 of the container 20 thus define a cylindrical 
storage chamber 46. The storage chamber 46 contains pressurized inflation 
fluid such as, for example, nitrogen, argon, or a mixture of oxygen with 
an inert gas such as nitrogen and/or argon. 
A cylindrical inner portion 48 of the second end wall 26 projects axially 
from the base portion 38 into the storage chamber 46. The inner portion 48 
defines a cylindrical combustion chamber 50 which contains a charge of 
ignitable gas generating material 52 (shown schematically). The gas 
generating material 52 may have any suitable composition known in the art. 
The combustion chamber 50 has an inlet opening 54 and a plurality of 
intermediate openings 56. The inlet opening 54 is centered on the axis 27, 
and is closed by a rupturable closure disk 58. Like the closure disk 30 at 
the opposite end of the container 20, the closure disk 58 is fixed and 
sealed to the corresponding end wall 26 of the container 20 by a 
circumferentially extending weld 60. 
The second end wall 26 of the container 20 further has an outer portion 80. 
The outer portion 80 has a pair of bevelled outer edges 82 (FIG. 3), but 
otherwise has a generally rectangular configuration with a length 
extending diametrically across the axis 27 and a height extending outward 
along the axis 27. 
The outer portion 80 and the base portion 38 of the end wall 26 together 
define a conduit 83. A first section 85 of the conduit 83 extends outward 
from the inlet opening 54 along the longitudinal axis 27. A second section 
87 of the conduit 83 extends from the first section 85 along a transverse 
axis 89 perpendicular to the longitudinal axis 27. The conduit 83 thus has 
a 90.degree. turn at the juncture of the first and second sections 85 and 
87. Moreover, the second section 87 of the conduit 83 has a widened open 
end portion 90. A planar outer surface 94 of the second end wall 26 
surrounds the open end portion 90. 
An initiator assembly 100 is mounted on the second end wall 26 of the 
container 20, as best shown in FIGS. 2 and 3. The initiator assembly 100 
includes an initiator 102 and a connector 104. The initiator 102 in the 
preferred embodiment of the present invention is an electrically 
actuatable squib with a cylindrical casing 106 and a pair of electrical 
contact pins 108. As known in the art, the casing 106 contains a small 
charge of pyrotechnic material which is ignited upon the passage of 
electric current through the initiator 102 between the contact pins 108. 
The connector 104 is a tubular cylindrical part centered on the transverse 
axis 89. An annular inner wall portion 110 of the connector 104 is located 
axially between first and second cylindrical compartments 112 and 114 
within the connector 104. The initiator casing 106 and a surrounding 
plastic support body 116 are insert molded together in the first 
compartment 112. The contact pins 108 project axially from the first 
compartment 112 into the second compartment 114. A plastic socket 120 is 
molded in place in the second compartment 114. The socket 120 is shaped to 
receive an electrical terminal (not shown) for connection of the initiator 
102 in an electrical circuit in a vehicle. 
A first end portion 122 of the connector 104 is received in the widened 
open end portion 90 of the conduit 83. An annular, radially outwardly 
projecting flange 124 on the connector 104 abuts the planar outer surface 
94 of the end wall 26. The flange 124 is fixed and sealed to the end wall 
26 at the outer surface 94 by a circumferentially extending weld 126. A 
second end portion 128 of the connector 104 projects from the end wall 26, 
and has an external screw thread 130 centered on the transverse axis 89. 
A diffuser 150 is mounted on the inflator 14 at the first end wall 24 of 
the container 20. The diffuser 150 is a cup-shaped structure with a 
circular end wall 152 and a cylindrical side wall 154. The end wall 152 of 
the diffuser 150 is centered on the longitudinal axis 27, and is 
preferably closed throughout its entire area. The side wall 154 projects 
axially from the end wall 152, and has a plurality of inflation fluid 
outlet openings 156 in a circumferentially extending array. An annular 
edge portion 158 of the side wall 154 is crimped against an annular rim 
structure 160 at the outside of the first end wall 22. The diffuser 150 is 
thus fixed and sealed to the container 20 circumferentially entirely 
around the axis 27. 
The diffuser 150 further has a screw-threaded mounting stud 162. The 
mounting stud 162 projects radially from the side wall 154 along a 
transverse axis 163 which is parallel to the transverse axis 89 at the 
second end wall 26. 
The air bag 12, the inflator 14 and the base plate 16 are interconnected, 
as shown in FIG. 1, by first placing a base portion 170 of the air bag 12 
between the inflator 14 and the base plate 16. The base portion 170 of the 
air bag 12 has a pair of apertures 172 and 174. The second end portion 128 
of the connector 104 and the mounting stud 162 are received through the 
apertures 172 and 174, respectively, and further through another pair of 
apertures 176 and 178 in the base plate 16. A fastener in the form of a 
nut 180 is received on the mounting stud 162. The nut 180 is tightened 
against the base plate 16 to fasten the diffuser 150 and the inflator 14 
to the base plate 16. Another fastener in the form of a nut 182 is 
received on the second end portion 128 of the connector 104, and likewise 
fastens the connector 104, the initiator 100 and the inflator 14 to the 
base plate 16. The base portion 170 of the air bag 12 is thus clamped 
between the inflator 14 and the base plate 16. 
As noted above, the initiator 102 is connected in an electrical circuit 
when the apparatus 10 of FIG. 1 is installed in a vehicle. As shown 
schematically by way of example in FIG. 4, such an electrical circuit 190 
includes a power source 192, which is preferably the vehicle battery or a 
capacitor, and a normally open switch 194. The switch 194 is part of a 
crash sensor 196 which senses a vehicle condition indicating the 
occurrence of a crash. The crash-indicating condition may comprise, for 
example, sudden vehicle deceleration that is caused by a crash. If the 
crash-indicating condition is at or above a predetermined threshold level, 
the switch 194 closes and electric current flows through the circuit 190. 
Electric current is then directed through the initiator 102 between the 
contact pins 108 (FIGS. 2 and 3) to actuate the initiator 102. 
When the initiator 102 is actuated in the foregoing manner, the pyrotechnic 
material in the casing 106 is ignited and generates products of combustion 
including heat, hot particles and hot gases. The combustion products are 
spewed into the conduit 83 from the casing 106, and are thus directed from 
the casing 106 to the rupturable closure disk 58 at the inlet opening 54. 
The closure disk 58 ruptures under the influence of the heat and pressure 
of the combustion products in the conduit 83. The combustion products then 
move into the combustion chamber 50 through the inlet opening 54 to ignite 
the gas generating material 52. The gas generating material 52, in turn, 
generates combustion products including heat and gases. Those combustion 
products move rapidly from the combustion chamber 50 to the storage 
chamber 46 through the intermediate openings 56. This heats and further 
pressurizes the inflation fluid in the storage chamber 46 to a level at 
which the force of the fluid pressure ruptures the closure disk 30 at the 
outlet opening 28. The heated, further pressurized inflation fluid then 
flows outward through the outlet opening 28 and the diffuser openings 156 
to inflate the air bag 12. 
From the above description of the invention, those skilled in the art will 
perceive improvements, changes and modifications. Such improvements, 
changes and modifications within the skill of the art are intended to be 
covered by the appended claims.