Airbag module door tether attachment

Abstract: Automotive airbag installation including an airbag module (10) containing an inflator (18) and an airbag (20) and two tethers (42a, 42b) a first end of each of which is attached to a breakaway cover portion of an instrument panel and a second end of each of which is connected by means of an anchor (44) to a channel (28a, 28b, 28c) formed in a side wall (13) of a module housing. Each anchor (44) includes a pair of pins (50) which can be slipped into the channels prior to rotation of the anchor (44) about the pins (50) so as to allow an anchor pawl to engage a detent slot formed in the side wall (13).

Description: This invention relates to motor vehicle airbag installations. More particularly, it relates to passenger side airbag module door restraints. Passenger side airbag systems are comprised of two major components. One component is the airbag module itself. Basically, it is in the form of a reaction canister which houses the inflator and airbag. It may also include a dust cover to protect the airbag. The airbag module is usually manufactured separately for later incorporation into the motor vehicle. The second component of the passenger side airbag system is the airbag door. This door is normally a portion of the automotive instrument panel but is designed to break away under the influence of the expanding airbag. It is important to restrain the door and limit its travel. One popular method of providing restraint is by use of a strap or tether. This allows a non-rigid attachment such that the fit and finish between the door and the instrument panel may be maintained, even throughout minor adjustments in the positioning of the module assembly. An example of such a passenger side airbag system is described in EP-A-0 465 869 (on which the pre-characterising part of claim 1 is based). The system includes a cover which overlies an open end of a canister in which a folded airbag is accommodated. A flexible tether connects the underside of the cover with an edge region of the canister and acts to restrain the cover when the airbag is deployed. A further passenger side airbag system is described in EP-A-0 638 464 which claims a priority date of 9 August 1993 and was published on 15 February 1995. This system also includes a cover which overlies an open end of a canister in which a folded airbag is accommodated. One end of a flexible tether is secured to the cover and a loop at the other end of the tether is inserted into a rearwardly opening C-shaped channel running the length of the canister where it is retained by means of a rod which is slid into the channel and through the loop. When the connection between the tether and the module assembly is made during the automobile assembly, it is important to provide a simple yet robust connection scheme and to minimize any tendency of the assembly to rattle when the vehicle is in motion. Accordingly, it is a primary object of the present invention to provide an airbag module assembly wherein the tether to module connection is made by a simple snap-in connection. Other objects, features and advantages will become apparent from the following description and appended claims. The invention comprises a flexible tether which has a first end secured to the breakaway door or cover formed in the instrument panel. A tether anchor is secured to the second end of the tether. Means are provided on the module for making a snap-fit engagement with the tether anchor while still providing firm support during cover breakaway. The invention will now be described by way of example only with reference to the following figures in which: FIG. 1 is an isometric view of a passenger side airbag module assembly in accordance with the present invention including the anchor ends of two tethers; FIG. 2 is a cross-section taken substantially along the line 2-2 of FIG. 1 and including the breakaway door portion of the instrument panel; and FIG. 3 is an enlarged detail illustrating the manner in which the tether anchor engages the module assembly. FIG. 1 illustrates a passenger side airbag module assembly 10 . It comprises a trough-shaped reaction canister having sidewalls 12 , 13 and a floor 15 . The reaction canister may be formed, for example, from an aluminum extrusion. The ends of the reaction canister are closed by end plates 14 , 16 so as to house a cylindrical inflator 18 (FIG. 2 ) and a folded airbag 20 . The edges of the sidewalls 12 , 13 and end plates 14 , 16 opposite the floor 15 form an open mouth. The reaction canister is provided with screw preparations 22 as needed for attaching the end plates and with airbag mouth retaining channels 24 , 26 . However, as these form no part of the present invention, they will not be further described. The reaction canister, however, does have additional features which form a part of this invention. In the illustrated embodiment, these include three circular channels 28a , 28b , 28c . These channels are coaxial and extend outwardly from the sidewall 13 of the reaction canister and the cylindrical sidewall of each channel defines a slot 30 (FIG. 3 ). It is important to note that, as shown in FIG. 1 , the opening of each slot 30 faces away from the open mouth of the reaction canister. The second feature of the reaction canister which relates to this invention comprises a slot 32 which is also formed in the sidewall 13 of the canister between its open mouth and the channels 28 . The slot 32 is parallel to the coaxial channels 28 and extends the length of the reaction canister sidewall 13 to form a detent 34 surrounded internally of the canister by a cylindrical extrusion 36 , as illustrated in FIG. 3 . A dust cover 38 of a material such as paper may optionally be employed to close the mouth of the reaction canister to protect the airbag 20 . This is particularly true if the airbag module is to be shipped to the assembly site. The vehicle destined to receive the module assembly of this invention includes an instrument panel P (FIG. 2 ). The panel has a breakaway cover 40 portion designed to separate from the instrument panel to form one or more doors during airbag deployment. Securely fastened to the breakaway cover 40 is one end of a flexible tether 42 . Two such tethers 42a and 42b are illustrated. However, one may be sufficient. The tethers may be of fabric or any other suitable material. The free end of each tether is connected to an anchor 44 . As the tether anchors are identical, only one will be described in detail. Each anchor comprises a plate 46 having a slot 48 (FIG. 2 ) through which the tether 42 is threaded and then secured back upon itself by any suitable means, such as stitching or adhesive. The distal edge of the plate 46 carries a pin 50 . The pin 50 extends outwardly from the side edges of the plate 46 . The pin 50 can be a unitary pin as shown or can comprise discrete first and second spaced, axially aligned pin members extending from each side edge of the plate 46 . As will be apparent from FIG. 1 , the dimensions of the plate 46 are such as to be received between one pair of channels 28 . Pin 50 is dimensioned so as to slip-fit into channels 28 from the open axial sides 29 thereof and form a male connection with the female channels 28 , as illustrated in FIG. 3 . Whether unitary or discrete, the pins of an anchor plate 46 are insertable into respective first and second spaced, axially aligned channels 28 . Slot 30 permits anchor plate 46 to move axially through channels 28 . This slip-fit may be made by the installer after installation of the module assembly 10 , without the need for disturbing the fit of cover 40 within the instrument panel P . In order to prevent any rattle or misalignment of anchor 44 after installation, a latch is provided to retain the anchor 44 in fixed alignment with the reaction canister sidewall 13 . As illustrated in FIG. 3 , this comprises a tongue 52 which extends the width of plate 46 and terminates in a pawl 54 . After inserting the pins 50 through their respective slots 30 , the anchor 44 is simply rotated, causing the pawl 54 to enter the slot 32 and make a snap-fit engagement over detent 34 . This retains the anchor in position and prevents rotation of the pins 50 in their channels. As previously explained, the slots 30 of the channels 28 point away from the instrument panel cover. As a result, when the cover 40 breaks away into a position 40' as illustrated in FIG. 2 , the force exerted by the extended tether 42' is such as to seat the pin 50 into firmer engagement with its channel. It is believed that the many advantages of this invention will now be apparent to those skilled in the art. For example, the male-female function of the anchor/module assembly or of the snap-fit latch members may be reversed, i.e. the female connection can be located on the anchor and the male pin on the module assembly and the detent may be carried by the anchor and the pawl carried by the module assembly.

Claims: An automotive airbag installation including: an airbag module assembly (10) which is mountable behind a breakaway cover (40), said airbag module assembly including a reaction canister for containing an inflator (18) and a folded airbag (20) therein and having an open mouth facing said cover; and a tether (42a, 42b) a first end of which is securable to said breakaway cover (40) and a second end of which is connectable to said module assembly (10) to provide firm support during cover breakaway resulting from airbag deployment, characterised in that: said second end of said tether (42a, 42b) is connected to said module assembly (10) by means of an anchor plate member (44) secured to the second end of said tether (42a, 42b); and means are provided for making a slip-fit engagement between said module assembly (10) and said anchor plate member (44), said engagement means comprising a male connector (50) on one of said anchor plate member (44) and module assembly (10) and a female connector on the other of said anchor plate member and module assembly wherein said female connector comprises a channel (28a, 28b, 28c) having a sidewall defining a slot (30) therethrough and said male connector is insertable through an axial open end (29) of said channel. The installation according to claim 1 wherein said male connector (50) is on said anchor plate member (44). The installation according to claim 1 or 2 wherein said female connector comprises at least one substantially cylindrical channel (28a, 28b, 28c) having a sidewall defining said slot (30) therethrough and said male connector comprises a pin (50) insertable through an axial open end of said cylindrical channel. The installation of any preceding claim wherein said female connector comprises first and second spaced, axially aligned channels (28a, 28b, 28c) and said male connector comprises first and second spaced, axially aligned pins (50) insertable into the respective first and second channels. The installation according to claim 3 or 4 additionally comprising means (34, 52, 54) for substantially preventing rotation of the or each pin (50) within the or each channel (28a, 28b, 28c). The installation according to claim 5 wherein said rotation preventing means (34, 52, 54) comprises a latch interconnecting said anchor plate member (44) and said module assembly (10) at a point on said anchor plate member spaced from said pin (50). The installation according to claim 6 wherein said latch comprises a detent (34) on one of said anchor plate member (44) and module assembly (10) and a pawl (54) on the other of said anchor plate member and module assembly. The installation according to claim 7 wherein said detent (34) is carried by said module assembly (10) and said pawl (54) is carried by said anchor plate member (44). The installation according to claim 8 wherein said detent (34) is a channel formed in said module assembly (10) and substantially parallel to said cylindrical channel (28a, 28b, 28c). The installation according to claim 8 or 9 wherein said pawl (54) compress a tongue (52) extending from said anchor plate member (44) and latchingly engageable with said detent (34) upon rotation of said anchor plate member (44) about said pin (50) within said substantially cylindrical channel (28a, 28b, 28c). The installation according to any one of claims 6 to 10 wherein said latch interconnects said anchor plate member (44) and said reaction canister of said module assembly (10). The installation according to claim 2 or any claim dependent thereon, wherein the channel (28a, 28b, 28c) of said female connector faces away from said open mouth of said reaction canister. The installation according to any preceding claim including an instrument panel having a breakaway portion therein forming said cover (40), wherein said reaction canister is substantially trough-shaped and mounted behind said cover (40), said canister having first and second sidewalls (12, 13), a floor (15), and first and second end plates (14, 16) for containing said inflator (18) and said folded airbag (20), therein, and wherein the or each channel (28a, 28b, 28c) is integral with, and protrudes from, said first sidewall (13) and is slotted along its length to receive a hinge pin (50) constituting said male connector therein in slip-fit engagement.

Inventors: GREEN DAVID J, RAVENBERG MICHAEL J, GREEN, DAVID J., RAVENBERG, MICHAEL J.
Applicants: MORTON INT INC, MORTON INTERNATIONAL, INC.
Application year: 1995
Main classification: B60R21
IPC codes: B60R21