Land vehicles – Wheeled – Attachment
Utility Patent
1998-09-14
2001-01-02
Swann, J. J. (Department: 3611)
Land vehicles
Wheeled
Attachment
C280S731000
Utility Patent
active
06168189
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention pertains to the field of airbag covers, such as are used in automobile steering wheels, and more specifically to tear seams, deployment doors and hinges in airbag covers.
Tear seams in airbag covers tear upon the deployment of an airbag. Conventional airbag covers feature tear seams which consist of a groove in the airbag cover. The groove provides a weakened place in the airbag cover wherein the deploying airbag can easily break through. Generally, the groove has a thickness less than that of the other portions of the airbag cover. This reduced thickness weakens the tear seam such that it ruptures upon deployment of the airbag.
Because the tear seam is of a reduced thickness, the tear seam can be visible as an indented line in the airbag cover. Conversely, tear seams may be hidden from view by being embodied in the reverse side of the airbag cover such that it is not visible to an occupant of the vehicle.
The grooves which create conventional tear seams have substantially constant depths. Because these depths do not vary, the tensile strength of the tear seam remains substantially the same throughout the tear seam. While this tensile strength is weaker than that of the remaining area of the airbag cover such that the tear seam tears before any other part of the airbag cover, the tearing of the tear seam is not easily controllable. Neither the rate of tearing of the tear seam nor the location along the tear seam wherein the tear seam first tears is easily controllable. Thus, for example, if an end of the tear seam tears before the center of the tear seam, the airbag will not deploy evenly. Rather, the airbag will deploy through the end of the tear seam, which tears first, and then push its way through the remainder of the tear seam. This could result in less than optimal deployment of the airbag.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, an airbag cover is provided which has a novel tear seam. The tear seam is a groove formed in the front of the airbag cover as well as a groove formed in the back of the airbag cover. These front and back grooves are slightly out of alignment, being separated by a thin transverse layer of the airbag cover. The transverse layer has a length and width, both of which vary at different locations along the tear seam. The centerline of the transverse layer is oriented at an angle with respect to the airbag cover. Like the transverse layer's length and width, this angle varies at different locations along the tear seam.
According to another aspect of the present invention, the tear seam defines a pair of deployment doors in the airbag cover. The deployment doors are formed in the airbag cover and open by rotating around hinges upon the deployment of the airbag. The hinges may be formed in the airbag cover by removing a portion of the back side of the airbag cover. The airbag cover may also comprise reinforcing means to strengthen the hinges.
According to another aspect of the present invention, the airbag cover has an essentially circular configuration. This differs from conventional airbag covers that have substantially square or rectangular configurations.
One advantage of the present invention is that variation of the transverse layer's length, width and angle permits the tearing of the tear seam to be controllable. The speed at which the tear seam tears and the speed at which the deployment doors open, as well as which part of the tear seam tears first can, be controlled. Additionally, fatigue failure can be prevented at locations along the tear seam, which receive considerable stress. For example, in designs where the vehicle horn is activated by depressing the airbag cover, the portion of the tear seam running through the section of the airbag cover that is depressed when the driver activates the horn can be configured to have a greater integrity.
Another advantage of the present invention is the reduction in material mass in a portion of the back side of the airbag cover. The removal of some material forms hinges within the airbag cover to permit the deployment doors to pivot open to a greater degree without tearing the hinges. The reinforcing means also aids in preventing the deployment doors from completely detaching from the airbag cover during airbag deployment.
Another advantage of the present invention is that the tear seam, unlike conventional tear seams, enables an emblem to be mounted on the front side of the airbag cover. For example, a portion of the tear seam may be configured to follow a portion of the outline of the emblem. Such design is shown herein as a semi-circle in the middle of the airbag cover. This would permit a round emblem to be mounted onto the front of the airbag cover. Upon deployment of the airbag, the tear seam would tear forming two doors out of the airbag cover. The doors would open and the airbag would deploy through the airbag cover. The round emblem, outlined by the semi-circular tear seam prior to the deployment of the airbag, would then be retained on one of the doors of the airbag cover after the semi-circular tear seam tears and the airbag deploys through the airbag cover.
Still other benefits and advantages of the invention will become apparent to those skilled in the art to which it pertains upon a reading and understanding of the following detailed specification.
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Breed Automotive Technology Inc.
Drayer Lonnie
Shriver J. Allen
Swann J. J.
Vrioni Beth
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