Air bag module

The present disclosure relates to air-bag modules for motorized vehicles.

The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.

Generally, motor vehicles are equipped with both driver and passenger air-bag modules, which deploy to protect occupants in the motor vehicles. Some vehicles have knee air-bag modules as well as curtain air-bag modules. The air-bag module is typically activated when the motor vehicle is involved in an accident. Generally, a driver air-bag module is secured to a steering wheel with a spring clip assembly, and a horn switch is positioned between the air-bag module and the steering wheel. A passenger air-bag module is mounted in or near the instrument panel.

The present invention specifically relates to a driver air-bag module coupled to a steering wheel of a motor vehicle. The air-bag module includes housing and a cover that define a cavity for receipt of an air-bag. The cover has hooks to engage with the housing to secure the cover to the housing while permitting the cover to move relative to the housing to active a horn switch. The horn switch comprises two wires embedded in the housing, at least one of these wires reinforcing the housing. The air-bag expands to absorb kinetic energy of a driver of the motor vehicle during, for example, a frontal crash event. Many of the teachings of this driver air-bag module can be extended to other types of air-bag modules.

Further features, advantages, and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

The drawings described herein are not intended to limit the scope of the present disclosure in any way. The components in the figures are not necessarily to scale, emphasis instead is placed upon illustrating the principles of the invention. In the drawings:

FIG. 1A is a perspective view of a steering wheel with an air-bag module in accordance with the principles of the present invention;

FIG. 1B is a perspective view of the air-bag module;

FIG. 2 is an expanded view of the air-bag module in accordance with the present invention;

FIG. 3A is a partial cross-sectional view of the air-bag module;

FIGS. 3B-3D are partial cross-sectional views of the air-bag module illustrating the attachment of a cover to a housing;

FIG. 4 is a perspective view of the cover with at least a portion of a horn switch;

FIG. 5 is a perspective view of the housing with at least a portion of a horn switch;

FIG. 6A is a partial view of the cover attached to the housing;

FIG. 6B is a partial view of the cover attached to the housing illustrating a portion of the horn switch; and

FIG. 7 is a perspective view of the horn switch.

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

With reference to FIGS. 1-5 , an air-bag module 10 is shown for use with a steering wheel 11 of a motor vehicle. The air-bag module 10 includes a housing 12 , a shield 14 , a cover 20 , a cushion or air-bag 22 and a horn switch 25 with an upper wire 26 and a lower wire 28 . The housing 12 can take on many shapes. In FIG. 2 the housing 12 is triangularly shaped with sides 12 a , 12 b and 12 c . The height of each side varies with many factors such as the shape and height of adjacent portions of the steering wheel 11 . Housing 12 also includes a bottom 12 d with a center opening 12 e into which an inflator 18 is placed and secured in a known manner. Positioned on the bottom 12 d and about the opening 12 e is a cage 120 ; the cage has a raised side 122 with a plurality of cutouts or openings 124 . The cage 120 includes a top 126 with a plurality of openings 128 . Openings 124 are rectangular or square shaped while openings 128 are triangular shaped. The inflator 18 is mounted within the cage and the air-bag is placed about the cage. The bottom 12 d of the housing 12 includes a plurality of openings 23 in the form of narrow slits into which a corresponding leg 21 of the shield 14 is placed.

The shape of the shield 14 is, in general, complementary to the shape and height of the housing 12 . As can be seen in FIG. 2 , the shield 14 has a generally triangular shape. In the illustrated embodiment the shield 14 is formed of two substantially identical parts 14 a and 14 b . Depending upon the shape of the housing the shield can be one-piece. Each shield part 14 a , 14 b has a long side 14 c and short sides 14 d and e . Adjacent sections 14 c - 14 e and 14 c - 14 d are separated by a respective curved portion 17 a or 17 b . This relationship mimics the shape of the housing 12 . A lower edge of each shield part 14 a,b includes a plurality of legs 21 . Each leg 21 includes a narrow portion 21 A and an enlarged portion 21 B. Each slit 23 includes an enlarged portion 23 A and narrow portion 23 B extending toward a side of the bottom of the housing. To secure each shield part 14 a,b in place the entire leg 21 is placed in a corresponding slot 23 with the enlarged portion 21 B positioned below the bottom 12 e of the housing 12 and then the shield and each respective leg 21 is moved outward so the enlarged portion 21 B is moved below the adjacent narrow portion 23 B of the slit 23 with the narrow portion 21 A of the leg 21 seated in the narrow portion 23 B of the slit. In this manner the bottom of each shield part 14 a,b is secured to the housing 12 . The shield can be secured to the housing in a number of ways, for example using rivets or having the lower portions of each shield part welded to the housing. The shield can be formed as a part of the housing as the housing is molded.

Reference is made to FIG. 5 which is an orthogonal view of the interior of the module housing 12 . The housing includes two cylindrical structures 142 which are part of the interior wall of sides 12 a, b , and c of the housing 12 and function as an interior spring housing wall, each of which is part of one of two spring assemblies 140 . As can be seen the two shield parts 14 a,b lie against the inside wall of the housing 12 and have ends positioned adjacent the two cylindrical structures 142 . The spring assembly 140 includes a cylindrical housing 144 located outside of the cylindrical structure 142 . This relationship is shown in FIG. 5 . Housing 144 has a cylindrical lower portion 146 and a larger diameter upper portion 148 . The lower portion 146 functions as a support for a mounting pin 36 . The pin 36 can be press fit or screwed into portion 144 . The upper portion 148 supports a cover mounting spring 32 . Pin 36 has a large diameter portion 154 , a narrow pin portion 156 and a flat rectangularly shaped portion 158 . Portion 158 can also be seen in FIG. 4 . A spring retainer 160 secures spring 32 to the pin 36 . The spring 32 fits into a cup-like cavity 162 formed by the upper portion 148 . The upper portion 148 includes an annular projection 164 which centers the spring 32 . The retainer 160 includes a rectangular slit 168 slightly larger than the size of the flat portion 158 of the pin 36 . With the spring 32 in place, the retainer 160 is placed above the spring 32 and flat portion 158 with the slit 168 aligned to the flat portion 158 . The retainer 160 is pressed down, compressing the spring 32 so that the flat portion 158 of the pin 36 is freely within the retainer 160 . The retainer 160 is rotated 90 degrees to hold the retainer 160 , spring 32 , and pin 36 together. Numeral 172 is a portion of the trim on the steering wheel located near the housing 12 and cover 20 .

The housing 12 and the cover 20 define a cavity 15 for receipt of the air-bag 22 . The air-bag 22 is folded or otherwise formed into a compact configuration prior to or as it is being placed into the housing 12 ; the cover 20 is then position upon the housing 12 . The horn switch 25 of the present invention is positioned between the housing 12 and the cover 20 . As shown in FIGS. 2 and 3A and other figures, the shield 14 includes a free flexible portion 14 f and a fixed portion 14 g attached to the housing 12 . The assembly of the cover 20 and the horn switch 25 to the housing 12 are described in greater detail below. The housing 12 includes at least one attachment mechanism 19 , such as, for example, a conically shaped tip, clip, hook or flange, which are operable to couple the air-bag module 10 to a steering wheel armature with a spring clip mechanism as is known in the art.

The air-bag module 10 further includes an inflator 18 , a damper (optional) 24 and retainer ring 38 . When the air-bag module 10 is assembled, a set of studs 42 extends through the retainer ring 38 , the inflator 18 , a set of damper springs 40 positioned between the inflator 18 and the damper 24 , and the damper 24 itself. A set of nuts 44 are tightened onto the set of studs 42 to secure the components of the air-bag module 10 together.

The cover 20 is operable to protect the air-bag 22 . As illustrated the cover 20 includes a top 20 a which is generally triangular to match with the general shape of the housing 12 . As is known in the art the housing 12 and cover 20 can have any desired shape. Extending from the undersurface 20 b of the cover 20 is a wall 45 and a plurality of hooks 46 extend from the wall. Portions of the top 20 a extend radially outward from the wall. The housing 12 and cover 20 are formed with counterpart locking formations such as a hook and eye (or opening). Each hook 46 has an extending flexible leg 46 a which terminates in a hook or catch formation 46 b . As can be seen from FIGS. 2 and 4 , the length of the leg 46 a and hook 46 b is relatively short which reduces the mass of the cover 20 . This is important in that the cover 20 of the present invention is given limited resilient travel towards and away from the housing 12 . In essence the cover 20 floats relative to the housing 12 and air-bag 22 . Portions of the cover 20 are used to activate the horn switch 25 of the present invention. By making the cover 20 lightweight, the force needed to activate the horn switch 25 is reduced. As can be seen in FIG. 2 and other figures the housing 12 includes a plurality of openings 23 . The cover 20 is generally made from a polymeric material, such as polyester (TPE), but any other suitable material can be employed. In certain arrangements, the shield 14 is die cut from a sheet of plastic, and the air-bag 22 in its compact shape is wrapped in in a tearable material, muslin or some non-woven material and contained in the cavity 15 and partially surrounded by the shield 14 for further protection of the air-bag 22 .

The wires 26 and 28 can be formed from any suitable conductive material such as, for example, a high carbon steel alloy wire sometimes referred to as “music wire.” As such, the wires 26 and 28 are arranged as movable electrical conductors and are configured so that when in engagement, the wires 26 and 28 are capable of crossing or contacting in a plurality of locations 31 ( FIG. 7 ) forming electrical contacts or contact points to close the electric circuit of the horn switch 25 . When the two wires 26 and 28 are employed in the horn switch 25 , the plurality of contact points 31 accommodate normal usage of a motor vehicle horn in which the driver may press upon the air-bag cover 20 at one of many different points, each of which causes at least one contact 31 to be closed. As can be appreciated, the driver of the vehicle might press upon the center of the cover 20 or at its top, bottom, sides, etc. to activate the horn.

Respective ends 29 of each of wire 26 , 28 are adapted to be connected to one or more electrical connectors to form a terminal assembly 30 (see FIG. 2 ). The terminal assembly 30 provides communication of the horn switch 25 with an electrical control unit (not shown), which communicates a horn activation signal, produced upon contact of the wires 26 , 28 , to a horn.

With reference to FIGS. 4 and 5 , the cover 20 includes a set of locator openings 34 and the housing 12 includes a set of locator openings 60 . A guide pin 36 is secured to a respective locator opening 34 . Upon assembly each pin 36 extends into a locator opening 60 to center the cover 20 onto the housing 12 . A set of springs 32 is positioned between the cover 20 and the housing 12 to create a bias force that pushes the cover 20 and the housing 12 apart such that the cover 20 floats on the housing 12 .

Referring also to FIGS. 3A, 6A and 6B , each of the hooks 46 is inserted into an open region 13 of the housing 12 . The housing 12 includes a rail 48 . This rail 48 is formed as a laterally extending shoulder as shown in FIGS. 2, 5 and others. At least three or more respective pads 47 engage with a rail 48 of the housing 12 to control the axial position of the cover 20 with respect to the housing 12 . The details of this relationship are discussed below. The upper wire 26 is positioned in a trench 50 of the rail 48 , and the lower wire 28 is insert molded in an opening 52 formed in the rail 48 during molding. Accordingly, the arrangement of the wires 26 and 28 around the rail 48 provide structural reinforcement to the wall of the housing 12 .

The position of the shield 14 and the hooks 46 when engaged with the rail 48 define a space or gap 56 . During the assembly of the cover 20 to the housing 12 , an inclined distal end 49 of each hook 46 initially makes contact with a top corner of the rail 48 as shown in FIG. 3B . Note that the space or gap 56 ensures that the hooks 46 do not push down on the top of flexible portion 14 f . Downward force on the cover 20 and the inclination of the distal end 49 causes the hooks 46 to flex inwardly against the flexible portion 14 f of the shield 14 , as shown in FIG. 3B . The inward motion of each inclined distal end 49 causes an adjacent portion of the flexible portion 14 f to flex inwardly as well. Further downward movement of the cover 20 allows the hooks 46 to flex outwardly so that the pads 47 engage under the rail 48 . The pads 47 , on hooks 46 are widely spaced among the multitude of hooks 46 to establish a stable “A” datum plane for the rest position of the cover 20 . The location “B DATUM” and angular orientation “C DATUM” locators previously described completely define a single unique position for the cover 20 with respect to the housing 12 . During deployment, strain in the cover 20 engages all hooks 46 to keep the cover 20 in place as the air-bag 22 inflates to rupture the cover 20 and exit the housing 12 and cavity 15 through doors in the cover 20 defined by pre-established tear seams and hinges. Note that during the deployment of the air-bag module 10 (that is, when the air-bag 22 inflates), the air-bag 22 pushes laterally outwards against the shield 14 . The flexible portion 14 f of the shield in turn flexes outwardly against the hooks 46 , which secures the retention of the hooks 46 by the rail 48 . Hence, the cover 20 is attached to the housing 12 by hooks 46 that are urged to stay in engagement by the resistance of the shield 14 as the air-bag 22 inflates. The shield 14 secondarily keeps the air-bag 22 from hindering movement of the cover 20 as it operates the horn.

The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.