GB2306923A

GB2306923A - Cover retainer for airbag

Info

Publication number: GB2306923A
Application number: GB9700630A
Authority: GB
Inventors: Larry Rodger Warner
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1993-08-06
Filing date: 1994-06-24
Publication date: 1997-05-14
Anticipated expiration: 2014-06-24
Also published as: GB9700630D0; GB2306923B

Abstract

The opening edge of an airbag cover is retained against a reaction plate 22 supporting the airbag by a retention strap 238 attached to the edge of the cover. The retention strap is stretched to cause the strap to neck, passed into the channel 264 between a pair of jaws 260 and then relaxed so that the teeth 262 engage the strap. Pressure of the expanding airbag on the cover upon inflation causes the strap to stretch and disengage from the teeth to allow the cover to open.

Description

INFLATABLE RESTRAINT AIR BAG The present invention relates generally to air bags for vehicles and, more specifically, to a cover retainer assembly for an inflatable restrain air bag of a vehicle.

Reference is made to G.B. Patent Application No.

9412767.7. This application is divided out of G.B.

9412767.7.

It is known that vehicles may collide with obstacles during operation. As a result, automotive vehicles have provided various structures to lessen the effects of a collision type impact on an occupant compartment of the vehicle. For example, some automotive vehicles may include an inflatable restraint air bag to lessen the effects of a collision type impact.

It is also known to incorporate an air bag into a steering wheel assembly of a vehicle to lessen the effects of a frontal collision type impact on an occupant compartment of the vehicle. For example, the steering wheel assembly may have a steering wheel cavity, an air bag disposed in the cavity and a cover member closing the cavity. The cover member is fixedly secured to the steering wheel assembly and may have a central perforation extending laterally across which tears or separates when the air bag is deployed to allow the air bag to inflate and expand into the occupant compartment.

While air bags provide an advantage in lessening the effects from a collision type impact, one design constraint is that the material for the cover member must have a rupture strength satisfactory for cover release of the air bag. Also, another design constraint is that the cover member must rupture quickly, thereby allowing high opening forces for the air bag upon deployment. A further design constraint is that attachment hardware and tool assembly are required to assemble the cover member to the steering wheel assembly.

According to the present invention, there is provided an air bag retainer assembly comprising a support member having a cavity, an air bag disposed within the cavity, a cover member closing the cavity and having at least first and second edges, means for fixedly securing said first edge of said cover member to the support member, means for releasably retaining said second edge of the cover member to the support member to allow said cover member to swing open toward said first edge upon deployment of the air bag and a reaction member disposed within the cavity and secured to the support member, said first and second edges being retention straps connected to the cover member, said releasably retaining means having a jaw member attached to said reaction member and having a plurality of teeth spaced to form a channel, said second retention strap being disposed in said channel.

One feature of the present invention is that a cover retainer assembly is provided for an inflatable restraint air bag. The cover retainer assembly releasably retains a cover member to a steering wheel assembly. Further no attachment hardware is required for the cover member of the air bag retainer assembly embodying the invention. The present invention has an advantage that assembly time for the cover member is reduced and opening forces for the air bag are minimised upon deployment of the air bag. Further, the rupture strength of the material for the cover member as a factor for satisfactory cover release is minimised.

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: FIG. 1 is a front elevational view of a cover retainer assembly G.B. 9412767.7, illustrated in operational relationship to a steering wheel assembly in an occupant compartment of a vehicle; FIG. 2 is an exploded perspective view of the cover retainer assembly and steering wheel assembly of FIG. 1; FIG. 3 is a fragmentary plan view of the cover retainer assembly and steering wheel assembly of FIGS. 1 and 2; FIG. 4 is a partial plan view of a portion of an alternate embodiment of the cover retainer assembly of FIGS.1 through 3.

FIG. 5 is a partial perspective view of a portion of an embodiment of the cover retainer assembly according to the present invention; FIG. 6 is a partial perspective view of a portion of another embodiment of the cover retainer; and FIG. 7 is a sectional view taken along line 7-7 of FIG. 6 with the cover retainer assembly in an assembled state.

Turning now to the drawings and in particular to FIGS. 1 and 2 thereof, a cover retainer assembly 10, according to the present invention, is illustrated in operational relationship with a steering wheel assembly generally indicated at 12, and an occupant compartment 14 of a vehicle such as an automotive vehicle (not shown). It should be appreciated that the steering wheel assembly 12 is movable or rotatable and connected to the remaining structure of the vehicle as is known in the art.

The steering wheel assembly 12 includes a steering wheel 16 having a central steering wheel cavity 18. The steering wheel cavity 18 is generally rectangular in shape and has an opening facing into the occupant compartment 14.

Referring to FIGS. 1 through 3, the steering wheel assembly 12 also includes an air bag assembly, generally indicated at 20, disposed within the steering wheel cavity 18. The air bag assembly 20 includes a reaction plate 22 disposed within the steering wheel cavity 18 and having a pair of flanges 24 spaced laterally and secured to the steering wheel 16 by suitable means such as fasteners 26.

The reaction plate 22 is made of a metal material although a suitable plastic material may be used. The air bag assembly 20 also includes an air bag inflator 28 secured to the reaction plate 22 by suitable means such as fasteners (not shown). The air bag assembly 20 further includes a gas or air bag 30 retained to the reaction plate 22 by suitable means such as a riveted ring (not shown).

It should be appreciated that, upon a frontal collision type impact of the vehicle, the inflator 28 deploys gas into the air bag 30 to inflate the air bag 30.

The cover retainer assembly 10 controls deployment of the air bag 30. The cover retainer assembly includes a cover member 32 to close the opening of the steering wheel cavity 18. The cover member 32 is generally rectangular in shape and has a base portion 34 and side portions 36 extending from the base portion 34 generally perpendicular thereto. The cover member 32 also has retention straps 38 connected to the side portions 36 by living hinges 40. The cover member 32 is made of a suitable material such as a relatively lightweight, soft, thin layer of cloth, vinyl, plastic, leather or a combination thereof.

The cover retainer assembly 10 also includes fasteners 42 such as rivets for fixedly securing one of the retention straps 38 to the reaction plate 22. The cover retainer assembly 10 further includes a projection 44 extending outwardly from a flange 24 of the reaction plate 22, opposite to the flange 24 to which the retention strap 38 is fixedly secured. The projection 44 may extend perpendicularly outwardly or an angle. The projection 44 may also have an end flange (not shown) extending perpendicularly thereto at the free end thereof. The cover retainer assembly 10 also includes an aperture 45 which extends through the retention strap 38 to receiver the projection 44. It should be appreciated that one of the retention straps 38 is fixedly hinged to the reaction plate 22 and at least an opposed retention strap 38 is releasably retained to the reaction plate 22. It should also be appreciated that the two other sides of the cover member 32 may have retention straps 38 releasably retained to the reaction plate 22.

In operation, one of the retention straps 38 is fixedly secured to the reaction plate 22 by the fasteners 42. The opposite retention strap 38 is pulled toward the reaction plate 22 to stretch the retention strap 38 such that the projection 44 is disposed through the aperture 46.

When the inflator 28 is activated, the air bag 30 expands and presses outwardly on the cover member 32 until a predetermined force is achieved. At the predetermined force, the projection 44 ruptures and allows the cover member 32 to swing open or rotate toward the fixedly secured retention strap 38. As a result, the energy of the air bag 30 is managed and controlled to minimise the opening force of the air bag 30. Alternatively, the projection 44 may have a generally "V" shaped edge at the bottom thereof to cut the retention strap 38 as it stretches instead of rupturing the projection 44.

Referring to FIG. 4, an embodiment 110 of the cover retainer assembly 10 is shown. Like parts of the cover retainer assembly 10 have like reference numerals increased by one hundred (100). The cover retainer assembly 110 includes the retention strap 138, having a plurality of apertures 146 spaced longitudinally therealong. The cover retainer assembly 110 also includes an inner flange 150 spaced laterally from the retention strap 138 and connected to the side portion 136 by the living hinge 140. The cover retainer assembly 110 further includes a rib 152 disposed in a track 154 between the inner flange 150 and the retention strap 138 for a function to be described. Preferably, a plurality of ribs 152 are spaced along the track 154. The ribs 152 may be generally circular or rectangular in shape.

In operation of the cover retainer assembly 110, the cover member 132 is disposed over the opening of the steering wheel cavity 18 such that the flange 24 of the reaction plate 22 is disposed in the track 154 between the inner flange 150 and retention strap 138. One of the retention straps 138 is fixedly secured to the reaction plate 22 by the fasteners 42. The opposite retention strap 138 is moved toward the reaction plate 22 by pushing or compressing the cover member 132 toward the reaction plate 22. When this occurs, the ribs 152 engage the flange 24 until a predetermined force is achieved. At the predetermined force1 the ribs 152 buckle or collapse to allow the projection 144 to be disposed in one of the apertures 146. When the inflator 28 is activated, the air bag 30 expands and presses outwardly on the cover member 132.As this occurs, a generally V shaped edge 155 on the projection 144 cuts or tears the retention strap 138 and allows the cover member 132 to swing open or rotate toward the fixedly secured retention strap 138.

Referring to FIG. 5, an embodiment 210 of the cover retainer assembly 10 of the present invention is shown.

Like parts of the cover retainer assembly 10 have like reference numerals increased by two hundred (200). The cover retainer assembly 210 has the retention strap 238 elongated with apertures eliminated. The cover retainer assembly 210 also includes a jaw member 260 moulded integral to the reaction plate 22. The jaw member 260 has a plurality of teeth 262 spaced longitudinally and extending laterally inwardly on opposed sides to form a channel 264 for a function to be described. The retention strap 238 has a width greater than a width of the channel 264. It should be appreciated that the teeth 262 overlap the retention strap 238 when disposed in the channel 264.

In operation of the cover retainer assembly 210, one of the retention straps 238 is fixedly secured to the reaction plate 22 by the fasteners 42. The opposite retention strap 238 is pulled toward the jaw member 260 to stretch the retention strap 238 and cause the retention strap 238 to neck to a smaller width to fit into the channel 264. The retention strap 238 is disposed in the channel 264 and released. This release causes the retention strap 238 to expand and allows a portion of the teeth 262 to engage or bite the retention strap 238 to retain it in place. When the inflator 28 is activated, the air bag 30 expands and presses outwardly on the cover member 232.The pressure on the cover member 232 causes the retention strap 238 to stretch and neck down to a smaller width and disengages the teeth 262 to allow the cover member 232 to swing open or rotate toward the fixedly secured retention strap 238.

The retention strap 38, 138, 238 may be moulded as an accordion of a flexible material which may be stretched to co-operate with either the projection 44, 144 or jaw member 260 without making a longer mould. The retention strap 38, 138, 238 also may be made to different lengths and the projection 44, 144 or jaw member 260 may be located at various locations along the reaction plate 22 to obtain more or less stretch of the retention strap 38, 138, 238.

Referring to FIGS. 6 and 7, another embodiment 310 of the cover retainer assembly 10 is shown. Like parts of the cover retainer assembly 10 have like reference numerals increased by three hundred (300). The cover retainer assembly 310 includes a retention strap retainer 370 connected to the reaction plate 22 by a living hinge 371.

The retention strap retainer 370 has a generally rectangular bale 372 extending outwardly perpendicularly near the living hinge 371 for a function to be described. The retention strap retainer 370 also has a flange member 373 extending outwardly and generally perpendicular at a free end thereof.

The flange member 373 has a pair of locking tabs 374 spaced laterally by a flexible membrane 375 and extending outwardly for a function to be described.

The reaction plate 22 also has a groove 376 extending longitudinally in the flange 24. The groove 376 is generally rectangular in shape and has a pair of generally V-shaped recesses 378 extending laterally to receive the locking tabs 374. The reaction plate 22 also has a pair of laterally spaced projections 380 extending outwardly on opposed sides of the groove 376. The projections 380 have generally V-shaped inner edges 382 for a function to be described.

The retention strap 338 has a generally rectangular aperture 346 extending therethrough. The aperture 346 forms a generally U-shaped strap for a function to be described.

In operation of the cover retainer assembly 310, the cover member 332 is disposed adjacent the reaction plate 22.

The retention strap retainer 370 is rotated or rocked toward the groove 376 by the living hinge 371 such that the bale 372 engages an end edge of the aperture 346. This engagement moves the cover member 332 toward the reaction plate 22 and pulls the retention strap 338 into tension.

The locking tabs 374 engage the inner edges 382 of the projections 380 and are compressed inwardly as the membrane 375 flexes to dispose the projections 380 in the groove 376.

In the groove 376, the projections 380 return to their original position such that the inner edges 382 mate with the recesses 378 to form a snap-fit therein. It should be appreciated that the retention strap retainer 370 may be used in place of the fasteners 42. It should also be appreciated that the cover retainer assembly 310 provides serviceability by allowing removal and assembly with simple hand tools.

Preferably the retention straps are formed as corrugated straps which may be stretched to a linear shape.

Claims

1. An air bag retainer assembly comprising a support member having a cavity, an air bag disposed within the cavity, a cover member closing the cavity and having at least first and second edges, means for fixedly securing said first edge of said cover member to the support member, means for releasably retaining said second edge of the cover member to the support member to allow said cover member to swing open toward said first edge upon deployment of the air bag and a reaction member disposed within the cavity and secured to the support member, said first and second edges being retention straps connected to the cover member, said releasably retaining means having a jaw member attached to said reaction member and having a plurality of teeth spaced to form a channel, said second retention strap being disposed in said channel.

2. An air bag retainer assembly as claimed in claim 1, wherein said cover member has a base portion and side portions extending from said base.portion, said first and second retention straps being hingedly connect to said side portions.

3. An air bag retainer assembly as claimed in claim 1 or 2, wherein said retention straps are formed as corrugated straps which may be stretched to a linear shape.

4. An air bag retainer assembly as claimed in any one of claims 1 to 3, wherein said fixedly securing means comprises a rotatable retention strap retainer attached to the support member and having locking tabs and a groove on the support member to receive said locking tabs.

5. An air bag retainer assembly substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.