Patent Application
20130181429
The present invention relates generally to occupant protection systems for automotive vehicles and, more particularly, to a driver airbag assembly mounted in a steering wheel.
Current occupant safety systems in motor vehicles usually include a driver airbag to protect the vehicle driver against head, neck, and upper thorax injuries during a frontal collision. Driver airbags most commonly deploy from an airbag housing positioned in or on a center or hub of the steering wheel. Driver airbags deploy from the steering wheel housing to an inflated condition to cushion and prevent the driver's head and thorax from striking the steering wheel, dashboard, and other portions of the vehicle interior.
Proper placement and shaping of the driver airbag is important to minimize injury during a collision. It is known to utilize various types of internal tethers to control the inflated shape and positioning of the airbag relative to the steering wheel and the driver. One important injury mode that may be experienced by a vehicle driver during a frontal collision is flexion and extension of the neck as the driver's head is thrown forward relative to the shoulders and thorax.
In a disclosed embodiment, an airbag assembly for a motor vehicle comprises a steering wheel, an airbag housing mounted to the steering wheel, and an airbag attached to the housing that deploys therefrom when inflated. When the airbag is deployed, a head contact portion is above a horizontal centerline of the steering wheel and a chest contact portion is below the horizontal centerline, the head contact portion having a thickness greater than a thickness of the chest contact portion. An upper tether extends between the housing and a first location on a driver-facing panel of the airbag adjacent a dividing line between the head contact portion and the chest contact portion. A lower tether extends between the housing and a second location on the driver-facing panel on the chest contact portion.
In a further disclosed embodiment, an airbag assembly for a motor vehicle comprises a steering wheel, an airbag housing mounted to a hub of the steering wheel, and an airbag stored in the housing when in a deflated condition. The airbag comprises a rim-facing panel, a driver-facing panel, an upper tether extending between the housing and a first location on the driver-facing panel opposite from the hub, and a lower tether extending between the housing and a second location on the driver-facing panel below the first location. The tethers are located to shape the airbag in an inflated condition to have a head contact portion adjacent to the upper rim and a chest contact portion adjacent to the lower rim, the head contact portion being of a first thickness greater than a second thickness of the chest contact portion.
In a further disclosed embodiment, the airbag further comprises a wedge-shaped panel between and connecting the driver-facing panel and the rim-facing panel, the wedge-shaped panel being wider adjacent to an uppermost extent of the airbag
In a further disclosed embodiment, the head contact portion has a surface approximately parallel with a plane of the steering wheel
Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which:
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
Steering wheel 12 has a central portion or hub 12a located at a horizontal centerline of the wheel, an upper rim 12b, and a lower rim 12c. Upper and lower rim portions 12b, 12c may be attached to hub 12a by any number and/or configuration of spokes, as is well known in the art. A driver airbag housing 20 is located in or on the steering wheel hub 12a and contains an airbag (not visible in
An upper portion of airbag 22 is located adjacent to upper steering wheel rim 12b to provide a head contact portion 30, and a lower portion of the airbag is adjacent to lower rim 12c to provide a chest contact portion 32. Head contact portion 30 has a thickness TU (measured generally perpendicular to the plane of steering wheel 12) greater than the thickness TL of the chest contact portion 32.
The desired differential between the upper airbag thickness TU and lower airbag thickness TL is achieved by proper sizing/shaping of the airbag envelope (which may be made up or one or more panels) and by internal tethers 24, 25 as shown. Upper tether 24 is attached to airbag housing 20 and extends therefrom generally perpendicular to the plane of steering wheel 12. The other end of upper tether 24 is attached to driver-facing panel 22a at a location approximately at the dividing line between head contact portion 30 and chest contact portion 32. Upper tether 24 is preferably approximately 10 to 12 inches long. Lower tether 26 is attached to airbag housing 20 and extends at a downward angle as it extends away from airbag housing 20, being attached to driver-facing panel 22a at a location on the chest contact portion 32. Lower tether 25 is preferably approximately 6 to 8 inches long.
In the embodiment of the invention depicted, both tethers 24, 25 are straps in the approximate range of 2 to 4 inches wide and are secured to driver-facing panel 22a at the lateral center of the airbag (as best seen in
For purposes of comparison,
It should be noted that the driver's neck is in a relatively neutral position, i.e., it is not flexed forward, as a result of the greater thickness TU of the airbag at head contact portion 30 limiting the forward movement of the head. In
The disclosed inflated shape of airbag 22 is thus shown to provide safety benefits as compared with prior art airbag designs by limiting the forward flexion of the driver's neck, and thereby reducing the bending moment applied to the neck. The reduced thickness TL of the airbag at chest contact portion 32 also achieves a reduce compression loading on the driver's chest while still providing desired levels of cushioning and protection from injury. The disclosed driver-side airbag 22 also provides a surface in the head contact portion that is flatter than the prior art airbag 122, and so offers a more distributed force applied to the driver's face.
The upper tether 24 controls the shape and thickness of the upper portion (head contact portion) of the airbag which has a beneficial effect of reducing the driver's head acceleration and neck injury. The bottom tether 26 reduces the force applied to the driver's chest due to airbag contact. Therefore, a driver airbag of the disclosed shape can provide more balanced occupant protection in a frontal crash event.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
