Airbag cushion assembly with horn switch pocket

Abstract: A vehicle safety airbag cushion assembly (50) including an airbag cushion (52) with an open mouth (59) surrounded by a collar (58) and a strap (54) for holding the cushion (52) in a folded state prior to deployment. A first end (67) of the strap has a strap collar (62) which is connected to the airbag collar (58) and a second end (68) with tabs (72) which break away from the remainder of the strap upon deployment of the cushion. An open rectangular pocket (56) sewn to the strap (54) accommodates a horn switch (93) immediately below a horn activation face (97) of a cover (88) of an associated airbag module (85). Bolts (91) and nuts (92) clamp the cushion collar (58) and the strap between an annular retainer (89) and a housing (87) of the module.

Description: The present invention relates to a driver side airbag module horn switch attachment and, more particularly, to an airbag cushion assembly having a horn switch pocket for receiving a horn switch assembly. Driver side airbag modules, which include an airbag cushion and an airbag module cover, are normally positioned within a hub of a steering wheel of a motor vehicle. An annular retainer ring secures the airbag cushion to the airbag module, and a cushion strap holds the airbag cushion in a folded position prior to deployment. Both the airbag module cover and cushion strap include a tear seam or weakened portion for allowing the airbag cushion to break through and fully deploy during a collision or rapid deceleration of the motor vehicle. The hub of the steering wheel happens to be the same area which conventionally includes the horn switch. Accordingly, the airbag module cover must additionally serve to actuate the horn switch. A horn switch assembly normally includes suitable components such as a membrane type horn switch and a backing plate for example, and the horn switch assembly is attached to an inner surface of a horn actuation face of the airbag module cover by ultrasonic welding or heat staking. Mounting the horn switch assembly to the airbag module cover by ultrasonic welding or heat staking is a time consuming assembly process that increases the cost of manufacturing the airbag module. In addition, the horn switches are sometimes damaged by heat staking, requiring the replacement of both the horn switch assembly and airbag module cover since the entire airbag module cover must be replaced when replacing a damaged or defective horn switch assembly welded to the airbag module cover. Furthermore, heat staking puts constraints on the design, material and manufacture of the airbag module cover. US 5 265 905 A that forms the closest prior art according to the preamble of claim 1 shows an airbag cushion assembly with a horn switch pocket situated on a cushion retaining cover. An object, therefore, of the present invention is to provide an airbag module having a horn switch assembly mounted to avoid one or all of the problems associated with welding or heat staking a horn switch assembly to an airbag module cover. In carrying out this invention there is provided a cushion strap for use with a folded, inflatable airbag cushion having a collar defining an open mouth for receiving inflation fluid. The cushion strap comprises a tether and a horn switch pocket. The tether has a first end securable to the collar of the airbag cushion and is sized to bridge across the folded airbag cushion. A second end of the tether is securable to the collar of the airbag cushion to retain the airbag cushion in a folded condition. A weakened portion of the tether is breakable upon inflation of the airbag cushion. The horn switch pocket is sized to contain a horn switch assembly and has a marginal edge secured to the tether and a pocket opening sized to receive a horn switch assembly. According to another aspect of the present invention, an airbag cushion assembly for use in an airbag module is provided. The airbag cushion assembly comprises a folded, inflatable airbag cushion, a cushion strap and a horn switch pocket. The airbag cushion has a collar defining an open mouth for receiving inflation fluid, and the cushion strap has a tether. A first end of the tether extends from the collar of the airbag cushion and the tether is sized to bridge across the folded airbag cushion. A second end of the tether is secured to the collar of the airbag cushion to retain the airbag cushion in a folded condition. A weakened portion of the tether is breakable upon inflation of the airbag cushion. The horn switch pocket is sized to contain a horn switch assembly and has a marginal edge secured to the tether and a pocket opening sized to receive a horn switch assembly. A horn switch pocket according to the present invention allows a horn switch assembly to be mounted within an airbag module without being heat staked or welded to an airbag module cover. The invention together with further objects, features, advantages and aspects thereof, will be more clearly understood from the following description taken in connection with the accompanying drawings in which: FIG. 1 is an exploded view of an airbag cushion assembly according to the present invention, including an airbag cushion and a cushion strap having a horn switch pocket; FIG. 2 is a top elevational enlarged view of the airbag cushion assembly of FIG. 1 with the airbag cushion folded, the cushion strap retaining the airbag cushion in its folded position and the horn switch pocket located on top of the cushion strap and folded airbag cushion and containing a horn switch; and FIG. 3 is a side elevational further enlarged view, partially in section, of the airbag cushion assembly of FIG. 2 mounted within an airbag module. The same reference numerals refer to the same elements throughout the various figures. Referring to FIGS. 1 through 3, an airbag cushion assembly 50 according to the present invention is shown and includes an airbag cushion 52 , a cushion strap 54 and a horn switch pocket 56 . The airbag cushion 52 has a collar 58 forming an open mouth 59 and having four fastener receiving holes 60 . The cushion strap 54, which can be made from the same material as the airbag cushion 52, is for retaining the folded airbag cushion 52 in a folded condition and includes a collar 62 and a strap or tether 64. The collar 62 is similar to the collar 58 of the airbag cushion 52, defines four fastener receiving holes 65, and is positioned adjacent to the collar 58 of the airbag cushion 52 . The collar 62 of the cushion strap 54 could also be secured to the collar 58 of the airbag cushion 52 as a unitary piece by stitching for example. The tether 64 has a first end 67 extending from the collar 62 of the cushion strap 54 . In the alternative, the cushion strap 54 could be provided without the collar 62 and the first end 67 of the tether 64 could extend from the collar 58 of the airbag cushion 52. The tether 64 bridges across the folded airbag cushion 52 and has a second end 68 that is connectable either to the collar 58 of the airbag cushion 52, the collar 62 of the cushion strap 54 or a retainer ring. As shown, two tabs 70,72 defining fastener receiving holes 71,73 extend from the second end 68 of the tether 64 for attachment to a retainer ring as explained below. It is important that the tether 64 break upon deployment of the airbag cushion 52 so as not to interfere with the performance of the airbag cushion 52. The tether 64 should therefore be notched, perforated or otherwise have a weakened portion breakable upon cushion deployment. As shown, the weakened portion comprises the two tabs 70,72 as the tabs are relatively very narrow compared to the tether 64 so that the tabs will break upon cushion deployment. The horn switch pocket 56 is generally rectangular and has a marginal edge comprising two longer opposed edges 76,77 and two shorter opposed edges 78,79. As shown, the two longer opposed edges 76,77 and one shorter opposed edge 78 are secured to the tether 64 of the cushion strap 54 by stitching 80 , and the other shorter opposed edge 79 forms a pocket opening 81 sized to receive a horn switch assembly 83 . The horn switch pocket 56 is sized to contain the horn switch assembly 83 , and is positioned on the tether 64 so that the horn switch pocket is on top of the tether 64 and folded airbag cushion 52 . Referring to FIG. 3, the airbag cushion assembly 50 is mounted in an airbag module 85 also including an inflator 86 , a module housing 87 and an airbag module cover 88 . The collar 58 of the airbag cushion 52 and the collar 62 of the cushion strap 54 are sandwiched between an annular retainer ring 89 and the module housing 87 and secured with four fasteners comprising bolts 91 extending from the retainer ring 89. The bolts 91, which can be unitary with the retainer ring 89 , pass through the fastener receiving holes 60 of the collar 58 of the airbag cushion 52 and the fastener receiving holes 65 of the collar 62 of the cushion strap 54 and are secured with nuts 92 to secure the collar of the airbag cushion and the collar of the cushion strap to the retainer ring 89 . Two of the four bolts 91 also pass through the receiving holes 71,73 of the two tabs 70,72 extending from the second end 68 of the tether 64 to secure the second end of the tether to the module housing 87 . As shown in FIG. 1, the collar 58 of the airbag cushion 52 and the collar 62 of the cushion strap 54 are normally mounted or secured to the retainer ring 89 and bolts 91 to form a sub-assembly for shipping and handling prior to being mounted in the airbag module. The horn switch pocket 56 is shown containing the horn switch assembly 83 having suitable components such as a horn switch 93, a backing plate 94 and a lead 95 connecting the horn switch to a remote horn control circuit (not shown) for example. The airbag module cover 88 includes a horn activation face 97 having an outer surface 97a and an inner surface 97b. It is intended that a driver will apply pressure to the outer surface 97a of the horn activation face 97 of the airbag module cover 88 to activate the horn switch 93 of the horn switch assembly 83. The horn switch pocket 56 and horn switch assembly 83 are located directly below the inner surface 97b of the horn activation face 97 of the airbag module cover 88. For purposes of illustration, the airbag cushion 52 is shown loosely folded and packed within the airbag module cover 88. Actually, the airbag cushion 52 and horn switch assembly 83 are packed tightly against the inner surface 97a of the horn activation face 97 of the airbag module cover 88 so that the horn activation face does not have to be depressed very much to actuate the horn switch 93 . Also for purposes of illustration, the airbag cushion 52 is shown thicker than actual. The horn activation face 97 of the airbag module cover 88 has a tear seam 98 and a hinge 99. Upon deployment of the airbag cushion 52 the horn activation face 97 breaks at the tear seam 98 and swings out of the path of the airbag cushion about the hinge 99. The cushion strap 54 is preferably positioned with respect to the airbag module cover 88 so that when the airbag cushion 52 is deployed, breaking the tabs 70,72 , the tether 64 and horn switch pocket 56 will swing out of the path of the airbag cushion in the same direction as the horn activation face 97 of the airbag module cover 88. As shown, the horn switch pocket 56 is positioned on the tether 64 so that when the tether swings out of the path of the airbag cushion 52, the pocket opening 81 will generally face downwardly towards the collar 62 of the cushion strap 54 to reduce the chance of the horn switch assembly 83 being thrown out of the horn switch pocket. In the alternative, the cushion strap 54 could be positioned with respect to the airbag module cover 88 so that the tether 64 and horn switch pocket 56 will swing out of the path of the airbag cushion 52 in the opposite direction of the horn activation face 97 of the airbag module cover 88. In that case, the horn switch pocket 56 should be positioned so that the pocket opening 81 will face downwardly as the tether 64 swings out of the path of the airbag cushion 52 , and preferably so that the pocket opening extends below the tear seam 98 to ensure that the pocket opening will stay within the airbag module cover 88 upon deployment of the airbag cushion to minimize further the chance of the horn switch assembly 83 falling out. A horn switch pocket according to the present invention allows a horn switch assembly to be mounted within an airbag module without being heat staked or welded to an airbag module cover. The horn switch assembly is simply inserted into the horn switch pocket during assembly of the airbag module, and removed from the horn switch pocket during servicing or replacement of the horn switch assembly. Modifications are possible, for example, the horn switch pocket could be shaped differently than shown and described to accommodate a different horn switch assembly. Also the horn switch pocket could be secured to the tether by means other than stitching such as a suitable adhesive, for example.

Claims: An airbag cushion assembly (50) for use in an airbag module (85), the assembly comprising: an airbag cushion (52) having a collar (58) defining an open mouth (59) for receiving inflation fluid; and a horn switch holding means (56) sized to hold a horn switch assembly (83), a cushion restraint (54), the airbag cushion being folded, the cushion restraint (54) bridging across the folded airbag cushion to retain the airbag cushion in a folded condition, a weakened portion (70, 72) of the cushion restraint (54) being breakable upon inflation of the airbag cushion, and the horn switch holding means (56) having a marginal edge, at least a portion of which is secured to the cushion restraint (54) characterised in that the horn switch holding means comprises a pocket (56) sized to contain and having a pocket opening (81) sized to receive the horn switch assembly (83), the cushion restraint comprising a strap (54) including a tether (64) having first and second ends (67, 68) extending from the open mouth (59) of the airbag cushion (52), the portion of the marginal edge of the pocket (56) being secured to the tether (64) between its first and second ends. The airbag cushion assembly (50) of claim 1 further comprising a retainer ring (89) secured to the collar (58) of the airbag cushion (52). The cushion assembly (50) of claim 1 or 2 wherein the first end (67) of the tether (64) extends from the collar (58) of the airbag cushion (52) and the second end (68) of the tether is secured to the collar of the airbag cushion. The airbag cushion assembly (50) of claim 2 wherein the cushion strap (54) includes a strap collar (62) secured to the retainer ring (89) and from which the first end (67) of the tether (64) extends and wherein the second end (68) of the tether is secured to the retainer ring to retain the airbag cushion (52) in its folded condition. The airbag cushion assembly (5,0) of claim 4 wherein: the collar (58) of the airbag cushion (52) has a plurality of fastener receiving holes (60); the strap collar (62) has a plurality of fastener receiving holes (65); a plurality of fasteners (91) extend from the retainer ring (89) through the plurality of fastener receiving holes (60) in the collar of the airbag cushion and through the plurality of fastener receiving holes (65) in the strap collar to secure the collar of the airbag cushion and the strap collar to the retainer ring; and two tabs (70,72) extend from the second end (68) of the tether (64), each tab defining a fastener receiving hole (71,73) positioned around a fastener (91) of the plurality of fasteners to secure the second end of the tether to the retainer ring, the weakened portion of the tether comprising the two tabs. A cushion restraint (54) for use with a folded, inflatable airbag cushion (52) having a collar (58) defining an open mouth (59) for receiving inflation fluid, the cushion restraint (54) being sized to bridge across the folded airbag cushion to retain the airbag cushion in a folded condition, a weakened portion (70,72) of the cushion restraint (54) being breakable upon inflation of the airbag cushion; and a horn switch holding means (56) sized to hold a horn switch assembly (83) and having a marginal edge sized to receive a horn switch assembly, at least a portion of the marginal edge being secured to the cushion restraint (54), characterised in that the horn switch holding means comprises a pocket (56) sized to contain and having a pocket opening (81) sized to receive the horn switch assembly (83), the cushion restraint comprising a strap (54) including a tether (64) having first and second ends (67,68) securable to the collar (58) of the airbag cushion (52) the portion of the marginal edge of the pocket (56) being secured to the tether (64) between its first and second ends. The airbag cushion assembly (50) of any preceding claim or the airbag cushion strap (54) of claim 6, the cushion strap having a strap collar (62) securable to the collar (58) of the airbag cushion (52), the first end (67) of the tether extending from the strap collar, and the second end (68) of the tether being securable to the strap collar. The airbag cushion assembly (50) or strap (54) of any preceding claim further comprising a horn switch assembly (83) contained within the horn switch pocket (56). The airbag cushion assembly (50) or strap (54) of any preceding claim, the horn switch pocket (56) being generally rectangular with a marginal edge divided into two longer opposed edges (76, 77) and two shorter opposed edges (78,79), the two longer opposed edges and one shorter opposed edge (78) comprising a portion of the marginal edge secured to the tether (64) and the other shorter opposed edge (79) forming the pocket opening (81). The airbag cushion assembly (50) or strap (54) of any preceding claim wherein a portion of a marginal edge of the horn switch pocket (56) is secured by stitching (80). An airbag module (85) including the airbag cushion assembly (50) of any preceding claim wherein the horn switch pocket (56) is positioned on the tether (64) of the cushion strap (54) so that the horn switch pocket is located between the tether and a horn activation face (97) of an airbag module cover (88) of the airbag module when the airbag cushion assembly is mounted in the airbag module.

Inventors: BOYD KRISTEN KAY STITES, RICKS MERLE KAY, BOYD, KRISTEN KAY STITES, RICKS, MERLE KAY
Applicants: AUTOLIV ASP INC, AUTOLIV ASP, INC.
Application year: 1997
Main classification: B60R21
IPC codes: B60R21