Rollover air bag system

[0002] 1. Field of the Invention

[0003] The present invention relates to inflation systems for airbags used in vehicle occupant restraint systems, particularly truck occupant protection airbags deployed as a result of rollover of the vehicle.

[0004] 2. Description of the Prior Art

[0005] Airbag inflators commonly employ combustible precursors which, upon combination and reaction, either generate a gas (pyrotechnic devices) to inflate an airbag, or they generate heat used to expand a compressed gas and thereby inflate the airbag. Since the inflation gas is delivered to the airbag under pressure and at a highly elevated temperature relative to ambient conditions, the delivered gas loses heat and declines in temperature rapidly as it expands to fill the airbag. With cooling the inflation gas loses substantial pressure, with the consequence that the volume of airbag which can be inflated is restricted. Chemical inflators must typically be matched to the airbag they are intended to inflate, with each increase in size of bag requiring a larger inflator.

[0006] Due the restricted volume of space available on automobiles, and the need to have inflators which operate quickly in cases of collisions, chemical inflators have been favored for automobiles. Due to the great size of the automobile market, the manufacture of chemical airbag inflators enjoys substantial economies of scale, resulting in widespread acceptance of the devices in other applications, such as occupant restraint systems for trucks.

[0007] Trucks, however, have resources not generally available on automobiles. These resources include compressed air to operate the trafler brake lines and, in some cases, an air spring suspension. The air system supporting these devices includes air pumps and tanks of substantial volume for holding compressed air for the various vehicle systems.

[0008] It is an object of the invention to provide a system for inflating airbags, particularly on trucks, which are sized and positioned to protect truck occupants in case of rollover of the truck.

[0009] It is another object of the invention to provide a system for inflating airbags which is readily applicable to different sizes of airbags.

[0010] It is still another object of the invention to employ existing truck resources to support airbag inflation during rollover incidents.

[0011] According to the invention there is provided an airbag inflation system includes an air tank for compressed air, preferably a tank already used to support the operation of the truck brake system or suspension system. An outlet from the tank is provided, sealed with a frangible seal. A squib, is positioned with respect to the outlet to open the frangible seal upon actuation. Alternatively to a squib, an electrically actuable valve may be used. An air line connects the outlet to an airbag for inflation of the airbag from the tank. The tank is pressurized by a pump installed on the truck. Air tanks may be used in rollover events because rollover events are slow compared to transmission of the crash pulse during collision events. An advantage of the system is that their is little inflation gas cooling since the tank stores air at ambient temperatures. Larger airbags than are readily supported by chemically based inflators may be used.

[0012] Additional effects, features and advantages will be apparent in the written description that follows.

[0013] The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood. by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:

[0014] FIG. 1 is a side cutaway view of a truck cab illustrating positioning of a rollover airbag within the cab;

[0015] FIG. 2 is a side cutaway view of a truck cab illustrating a deployed rollover airbag;

[0016] FIG. 3 is a schematic illustration of an airbag deployment system in accord with the present invention; and

[0017] FIG. 4 is a cross-sectional view of a squib actuation system.

[0018] FIG. 1 illustrates a vehicle 10 having a passenger compartment 12. Within the passenger compartment is seated an occupant 14 on a seat 16. The occupant is restrained from unintentionally moving from seat 16 by a safety belt 18 which is worn around the waist and over the shoulder. An undeployed airbag 20 is positioned above, to the left and behind occupant 14, preferably behind a screen or other cosmetic device (not shown). In one embodiment, airbag 20 deploys along a track 26 running along the edge of a door (not shown) into the vehicle passenger compartment 12. Alternatively, airbag 20 may be installed in the roof to deploy downwardly or in other positions not requiring extremely rapid deployment.

[0019] FIG. 2 illustrates a deployed position of airbag 20 protecting occupant 14 in vehicle passenger compartment 12. As airbag 20 expands with the introduction of compressed air, the cushion expands causing an airbag restraining strap 24 attached to one end of the airbag to track forward and down in track 26 to bring airbag 20 to a position protecting the left side of the face of occupant 14. The second end of airbag 20 held in position at a pivot 28 mounted on the inside wall of passes compartment 12. Airbag 20 is of conventional construction except as to its manner of invention.

[0020] FIG. 3 is a schematic of an airbag deployment system 30 according to a preferred embodiment of the invention. Airbag deployment system 30 comprises a compressed air tank or reservoir 32, which is pressurized with ambient air from a pump 34 driven by the vehicle prime mover or engine 35. Compressed air tank 32 supplies various vehicle systems, such as the brakes 38 or suspension 40 with compressed air through a valve control arrangement 36.

[0021] A conventional rollover sensor 42 determines when, and in some embodiments how quickly, air is to be released from tank 32 to airbag 46 through air line 47. An airbag inflation signal is, responsive to sensor conditions indicative of a rollover event, supplied to an inflation controller 44, which may be a squib or a electrically controlled valve responsive to signal level.

[0022] FIG. 4 depicts a preferred squib 58 arrangement for initiating inflation of one or more airbags. Where control of the rate of airflow from compressed air tank 32 is not considered important, a squib 58 may be used to puncture a frangible seal 52 used to close an outlet from the interior 33 of compressed air tank 32. Frangible seal 52 is attached by spot welds 56 to an interior wall 51 of tank 32 along exterior seal flanges 54. An electrically actuated squib 58 is positioned by a retainer 62 in a plenum 60 opposite frangible seal 52. Upon actuation, squib 58 explodes into seal 52 tearing the seal open and allowing compressed air into plenum 60 and from plenum 60 through a vent 64 into air line 47. Air line 47 carries the airstream to an airbag connected to the opposite end of the air line.

[0023] The invention provides an inflation system for airbags, particularly on trucks, which allows the easy use of airbags sized and positioned to protect truck occupants in case of rollover of the truck. The invention provides a system for inflating airbags which is readily applicable to different sizes of airbags without changing the configuration of the airbag inflation system and makes use of existing air pressure systems on the truck.

[0024] While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.