Inflatable knee bolster airbag with internal tether

#This invention relates to an airbag module with an airbag having a tether for guiding the direction of the airbag.

#An airbag module typically has an inflatable airbag that serves as a cushion for a vehicle occupant in a crash. The airbag is connected to an airbag inflator, which emits a quickly expanding gas to deploy the airbag when a vehicle's crash detection system has sensed a crash. Airbags are used not only to protect a vehicle occupant from impact with a steering column of a vehicle but also against impact with other hard surfaces of a vehicle occupant compartment. Typically, this protection involves placing airbags to cover such areas as the upper part of a vehicle instrument panel as well as the sides of vehicle doors to protect against upper extremity injuries, such as injuries to the head.

#Manufacturers have also used cushioning devices to protect against injuries to the lower extremities of a vehicle occupant, such as knees and legs. In the past, this protection involved adding foam cushioning to the lower portions of the vehicle instrument panel. Recently manufacturers have considered using an active surface that deploys during a crash to create a cushion for the vehicle occupant. A challenge faced in the design of such devices is that a desirable location for deployment of these deploying devices is beneath the instrument panel. Airbags in such locations have a tendency to deploy horizontally toward the vehicle occupant. It has been very difficult to guide the airbag in a vertical direction to cover the front face of the instrument panel.

#The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows.

#FIG. 1 is a side view of the inventive airbag module with the airbag deployed between a vehicle instrument panel and a vehicle seat.

#FIG. 2 is a front view of the airbag of FIG. 1 highlighting sewn locations of the internal tether on a front panel of the airbag.

#FIG. 1 illustrates an inventive airbag module 10 with an airbag 14 fully deployed between a vehicle instrument panel 16 and a vehicle seat 12. As shown, in the inflated state the airbag 14 has an inflation chamber 17. A first portion 18 of the inflation chamber 17 that serves as a knee cushion for a vehicle occupant sitting in the seat 12 in the event of a crash. A second portion 22 of the inflation chamber 17 forms a neck that is attached to the back panel 34 of the first portion 18 of the inflation chamber 18 that serves as a knee cushion. The first portion 18 of the inflation chamber and the second portion 22 of the inflation chamber are in communication with an inflator 50 that is linked to a crash detection system 114 that controls deployment of the airbag 14 through known techniques. The inflator 50 can be a pyrotechnic inflator, a stored gas inflator or a hybrid inflator, all of which are well known to those of ordinary skill in the art. The airbag module comprises the airbag 14 and inflator 50 are stored in a module housing 94 until deployment.

#As shown the first portion 18 of the inflation chamber deploys in a direction indicated by arrow Y that is closer to being truly vertical than the second portion 22 of the inflation chamber which deploys in a direction indicated by arrow X that is closer to being truly horizontal than the first portion 18 of the inflation chamber. The geometry selected for the positioning of the deployed airbag is of course dependent upon the configuration of the vehicle in which the airbag is installed. Hence, the second portion 22 of the inflation chamber permits the first portion 18 of the inflation chamber to be placed horizontally in front of the vehicle instrument panel 16 when fully inflated as shown. The first portion 18 of the inflation chamber, here a knee cushion, has a front panel 30, a back panel 34, a first side panel 38 (as shown in FIGS. 2-4) and a second side panel 42 (as shown in FIGS. 2-4). As used herein and in the claims “front” refers to a direction facing the seat 12 of a vehicle which can receive a vehicle occupant, and “back” refers to a direction facing away from the to seat 12 of a vehicle which can receive a vehicle occupant when the airbag is deployed. Disposed within the first portion 18 of the inflation chamber is a tether 54, here a sheet of fabric as shown in FIG. 4. The tether 54 comprises a first portion 58 of the tether, a second portion 62 of the tether, and a third portion 66 of the tether. When the first portion 18 of the inflation chamber is fully deployed the first portion 58 of the tether extends generally parallel to the third portion 66 of the tether, while the second portion 62 of the tether is oriented transverse to both the first portion 58 of the tether and the third portion 66 of the tether.

#The first portion 58 of the tether 54 is secured by sewn stitches 118 attaching a first fold 98 of the tether 54 to a first front panel location 70 on the front panel 30 of the first portion 18 of the inflation chamber. The first portion 58 of the tether is also secured by sewn stitches 126 attaching a second fold 102 of the tether to a first back panel location 74 of the back panel 34 of the first portion 18 of the inflation chamber. The tether 54 is disposed across the first portion 18 of the inflation chamber along a diagonal relative to the first portion 58 of the tether. One end of the second portion 62 of the tether is sewn to the first back panel location 74 at the second fold 102 as indicated, and is secured by sewn stitches 122 attaching a third fold 106 of the tether 54 to a second front panel location 78 on the front panel 30 of the first portion 18 of the inflation chamber. The second front panel location 78 is vertically displaced from the first front panel location 70 as shown. One end of the third portion 66 of the tether is sewn to the second front back panel location 78 at the third fold 106 as indicated, and is secured by sewn stitches 130 attaching a fourth fold 110 of the tether 54 to a second back panel location 82 on the back panel 34 of the first portion 18 of the inflation chamber, which is vertically displaced from the first back panel location 74. While the means for attaching the tether to the front and back panels of the airbag is shown in this embodiment as sewing, it is understood that the means for attaching the tether to the front and back panels of the airbag may be any suitable means for attaching one piece of sheet material or fabric to another may be employed including but not limited to stitching, sewing, knitting, hot and cold applied adhesives, welding, heat staking and fasteners. This unique design of the tether 54 serves to guide the first portion 18 of the inflation chamber over the face 90 of the vehicle instrument panel 16 in an upward direction in the direction indicated by arrow Y.