GB2339408A

GB2339408A - Method of securing an airbag cover to an airbag housing

Info

Publication number: GB2339408A
Application number: GB9815060A
Authority: GB
Inventors: Jean-Chrisophe Partaix; Hughes Vendrand; Laurent Hellot
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1998-07-10
Filing date: 1998-07-10
Publication date: 2000-01-26
Anticipated expiration: 2018-07-10
Also published as: GB2339408B; GB9815060D0

Description

2339408 PATENTS ACT 1977 P12526GB-NF/isd "E"PROVEMENTS IN OR RELATING TO

AN AIRBAG UNIT"

Description of Invention

THIS INVENTION RELATES to an airbag unit, and more particularly relates to an airbag unit to be mounted in a motor vehicle, such as a motor car, at a position in front of the driver or front seat passenger of the vehicle.

Such airbag units have been proposed previously, and typically comprise a mounting plate or housing, to which is connected a cover, the mounting plate or housing and the cover together enclosing a chamber in which the airbag is packed in a folded condition. Typically the cover is made of a resilient plastic material which has elastic properties. The cover may have resilient portions, such as resilient locking arms which each snap over an outwardly directed flange or tongue provided on the mounting plate or housing to secure the cover in position. EP-A-0573154 discloses an arrangement of this type. In this airbag unit the locking arms are secured by blocking means which are fixed to the bottom of the housing. The locking arms are thus retained in the locking position. However, when the airbag is inflated the pressure exerted by the inflating airbag on the inside of the cover tends to release the locking arms by pushing them outwardly. The release of the locking arms is only prevented by the blocking means which, although having a complicated shape, are relatively weak.

2 The present invention seeks to prove an improved airbag unit.

According to this invention there is provided an airbag unit comprising a mounting plate or housing, and a cover mounted on the plate or housing, the cover and the plate or housing defining a chamber containing an airbag, the cover having sidewalls located adjacent the periphery of the plate or housing, the sidewalls being provided with resilient tongues, each tongue extending generally parallel with the adjacent sidewall, each tongue being provided with a first abutment adapted to be brought into cooperating engagement with a cooperating second abutment which is formed on the mounting plate or housing by a movement of the resilient tongue outwardly away from the centre of the mounting plate or housing to secure the cover to the mounting plate or housing.

Preferably said tongues are integral parts of the cover.

Conveniently the cover is made of a polymer with resilient properties.

Advantageously the first abutment is an aperture or recess in the resilient finger, and the second abutment is a protrusion directed towards the centre of the plate or housing.

Conveniently the second abutment is a tongue formed on the plate or housing at one edge of an aperture through which the resilient finger passes.

In an alternative embodiment the first abutment is a protrusion carried by the resilient finger and the second abutment is defined by an aperture formed in the plate or housing.

3 Conveniently the said protrusion forming the first abutment has an inclined undersurface and a horizontal upper surface and the aperture is formed in a peripheral upstanding flange provided on the plate or housing.

Preferably each finger is associated with a blocking element the blocking element being adapted to engage the finger and retain the finger in the position in which the abutments engage.

Conveniently the blocking element is formed integrally with the plate or housing.

Preferably the blocking element is in the form of a tab extending from one side of an aperture formed in the plate or housing.

Conveniently the blocking element is movable from a non-blocking position to a blocking position with a plastic deformation of the blocking element.

Alternatively the blocking element is movable from a non blocking position to a blocking position with an elastic deformation of the blocking element.

Advantageously means are provided to retain the blocking element in the blocking position.

Preferably the means to retain the blocking element in position comprise a protrusion on the tongue, said protrusion having a face adapted to be engaged by the blocking element, when in the blocking position, to retain the blocking element in the blocking position.

4 Preferably the plate or housing is of metal.

In order that the invention may be more readily understood, and so that fi,irther features thereof may be appreciated, the invention win now be described, by way of example, with reference to the accompanying drawings, in which:

FIGURE I is a vertical sectional view through part of one embodiment of an airbag unit in accordance with the invention, showing the components of the unit in a first position during manufacture of the unit, FIGURE 2 is a view corresponding to Figure I showing the components in a subsequent position, FIGURE 3 is a view corresponding to Figure 2 showing the components in a further subsequent position, FIGURE 4 is a view corresponding to Figure 3 showing the components in a final position, the view being taken on the line IV - IV of Figure 5, FIGURE 5 is a sectional view taken on the line V - V of Figure 4, FIGURE 6 is a view, generally corresponding to Figure 1, showing a second embodiment of a airbag unit according to the invention, with the component parts in a first position during manufacture, FIGURE 7 is a view corresponding to Figure 6 illustrating the components in a final position, FIGURE 8 is a view, generally corresponding to Figure 4, showing a third embodiment of an airbag unit according to the invention, and FIGURE 9 is a view, generally corresponding to Figure 4, showing a fourth embodiment of an air bag unit according to the invention.

Referring initially to Figure 1, an airbag unit comprises a mounting plate 1, which has a generally rectangular shape and which has an outer peripheral upstanding flange 2 and a central circular aperture 3. A gas generator 4 is mounted in position in the aperture 3.

Adjacent the periphery of the plate I there are a plurality of spaced apertures 5. Each aperture 5 has an inwardly directed tongue 6, extending in towards the centre of the aperture from the side of the aperture adjacent the periphery 2 of the plate 1. Thus the tongue 6 extends inwardly from the periphery of the plate towards the centre of the plate. Each aperture also has a deflected tab 7 which extends from the side of the aperture opposite the tongue towards the tongue. The tab 7 is deflected downwardly out of the plane of the rest of the plate 1.

The plate I is associated with a cover 10, which is formed of a resilient polymer. The cover has a rectangular top surface 11, and depending sidewalls 12. The sidewalls 12 are dimensioned to lie adjacent the peripheral flange 2 of the plate 1.

In the region of each of the apertures 5 'in the plate I the sidewall 12 of the cover carries, on its inner side, a resilient finger 13 which is formed integrally with the sidewall. The finger 13 extends parallel with the sidewall 6 and is spaced slightly inwardly from the sidewall. The finger is dimensioned so that the end of the finger 13 may pass through the aperture 5. At a position adjacent its lower end the finger is provided with a transverse aperture or recess 14 which is dimensioned to receive the tongue 6 of the aperture 5. At the very end of the finger there is a protrusion 15 which extends towards the centre of the plate 1, this protrusion 15 presenting a planar upper surface 16. The lowest part of the side of the finger 13 closest to the sidewall 12 is chanifered 17.

The cover 10 is to be assembled with the plate I and the gas generator 4 to define a chamber 20 which accommodates a folded airbag 2 1. As the cover is moved towards the plate I the upstanding peripheral flange 2 of the plate I is received between the finger 13 and the sidewall 12. The chamfered region 17 at the lower end of the finger engages the part of the plate I between the upstanding peripheral flange 2 and the aperture 5, and the finger is guided, as shown in Figure 2, to enter the aperture 5. The resilient finger, in this position, is flexed inwardly, towards the centre of the plate 1, away from the sidewall. 12.

As the end of the finger passes through the aperture 5, the recess or aperture 14 formed in the end of the finger become aligned with the tongue 6, and the resilient finger snaps back to its original position, with the tongue received within the aperture or recess 14. When effecting this movement the finger moves outwardly away from the centre of the plate or housing 1. The tongue 6 then acts as an abutment which is engaged by a co-operating abutment, in the form of the aperture or recess 14, the engagement of the two abutments retaining the cover in position on the plate 1.

Subsequently the tab 7 may be moved upwardly, with a plastic deformation of the tab, from an initial unblocking position to a final blocking position. The end of the tab will engage the undersurface of the protrusion 15 7 provided at the lower end of the finger 13, and this will tend to flex the finger 13 so that the lower end thereof is moved towards the adJ a- cent sidewall 12. As the tab 7 continues to move upwardly the end of the tab 7 will move to a position above the planar upper surface16 of the projection 15. The resilient finger 13 will then return to its initial position. When the tab 7 is released it will tend to move downwardly, but the end of the tab 7 will engage the planar upper surface 16 of the projection 15, and this will prevent substantial downward movement of the tab 7. Thus the tab 7 makes a snap connection with the finger and then acts as a blocking element which prevents movement of the resilient finger 13. The end of the tab 7 engages the finger 13 and prevents the finger 13 from flexing inwardly towards the centre of the plate I to release the finger from the tongue 6. This is the position shown in Figure 4.

It is to be understood that on inflation of the airbag the pressure applied by the inflating airbag to the cover will tend to move the resilient fingers 13 outwardly, away from the centre of the plate 1, thus reinforcing the engagement between the aperture or recess 14 in the resilient finger 13, and the tongue 6. Thus, on inflation of the airbag the housing is held very securely on the plate 1.

Figures 6 and 7 illustrate an embodiment which is substantially identical with that of Figures I to 5, with the exception that the protrusion 15 is omitted. In this embodiment the cover 10 is mounted on the plate I in the same way as in the embodiment described above, but as the tab 7 moves upwardly to its final blocking position it does not make a snap connection with the protrusion on the exterior of the tongue. In this embodiment the tab 7 may be configured to move elastically. Thus, as the finger 13 is introduced into the aperture 5 the end of the finger 13 may move the tab downwardly, away from its initial position, with an elastic deformation of the tab. The tab is thus stressed, and moved to an unblocking position. When the finger 13 has been moved to the 8 position in which the aperture or recess 14 in the finger is aligned with the tongue 6, thus permitting the finger 13 to flex back to its Hi-ditial position, the tab 7 will also move back to its initial position, releasing the stresses stored when it was initially moved with the elastic deformation. The tab 7 is thus moved to a blocking position in which movement of the resilient finger is blocked.

Figure 8 shows a fiu-ther modified embodiment which is similar to that of Figures 6 and 7. However in the embodiment of Figure 8 there is no through aperture formed in the resilient finger 13 to engage the tongue 6, but instead there is a closed recess 14. The closed recess defines the abutment that engages the tongue 6.

Figure 9 shows a modified embodiment of the invention in which the aperture 5 is not provided with a tongue 6 and in which the peripheral Range 2 of the plate 1 is provided with a rectangular aperture aligned with the aperture 5. Also the face of the resilient finger 13 that is directed towards the sidewall 12 is provided with a protrusion 21 that has an inclined undersurface 22 and a planar upper surface 23.

The components of Figure 9 will be assembled in the manner described above with reference to Figure I to 5. As the finger 13 moves downwardly the inclined undersurface 22 of the projection 21 will engage the upper edge of the peripheral upstanding flange 2 on the plate 1, thus deflecting the finger 13 inwardly. When the cover has been moved downwardly by a short distance the protrusion 21 will be aligned with the aperture 20 formed in the peripheral upstanding flange 2, and the finger will return to its initial position with the protrusion 21 received in the aperture 20. Upward movement of the cover is prevented by the engagement of the planar upper surface 23 of the protrusion 21, which acts as a first abutment, with the upper edge of the aperture 20, 9 which constitutes a second abutment. Again, in this embodiment the tab 7 serves to act as a blocking member to lock the resilient finger in position, and also the pressure applied to the cover, by the airbag, on inflation of the airbag, tends to reinforce the connection between the two abutments constituted by the upper surface 23 of the projection 2 1, and the upper edge of the aperture 20.

VAiile the invention has been described with reference to an embodiment in which the gas generator and the cover are mounted on a plate, in alternative embodiments the gas generator and the cover may be mounted on a housing

Claims

CLAIMS: 1. An airbag unit comprising a mounting plate or housing, and a cover mounted on the plate or housing, the cover and the plate or housing defining a chamber containing an airbag, the cover having sidewalls located adjacent the periphery of the plate or housing, the sidewalls being provided with resilient tongues, each tongue extending generally parallel with the adjacent sidewall, each tongue being provided with a first abutment adapted to be brought into cooperating engagement with a co-operating second abutment, which is formed on the mounting plate or housing, by a movement of the resilient tongue outwardly away from the centre of the mounting plate or housing to secure the cover to the mounting plate or housing. 2. A unit according to claim I wherein said tongues are integral parts of the cover. 3. A unit according to claim I or 2 wherein the cover is made of a polymer with resilient properties. 4. A unit according to any one of the preceding claims wherein the first abutment is an aperture or recess in the resilient finger, and the second abutment is a protrusion directed towards the centre of the plate or housing. 5. A unit according to claim 4 wherein the second abutment is a tongue formed on the plate or housing at one edge of an aperture through which the resilient finger passes. 6. A unit according to any one of claims I to 3 wherein the first abutment is a protrusion carried by the resilient finger and the second abutment is defined by an aperture formed in the plate or housing. 7. A unit according to claim 6 wherein the said protrusion forming the first abutment has an inclined undersurface and a horizontal upper surface and the aperture is formed in a peripheral upstanding flange provided on the plate or housing. 8. A unit according to any one of the preceding claims wherein each finger is associated with a blocking element, the blocking element being adapted to engage the finger and retain the finger in the position in which the abutments engage. 9. A unit according to claim 8 wherein the blocking element is formed integrally with the plate or housing. 10. A unit according to claim 9 wherein the blocking element is in the form of a tab extending from one side of an aperture formed in the plate or housing. 11. A unit according to claim 9 or 10 wherein the blocking element is movable from a non-blocking position to a blocking position with a plastic deformation of the blocking element. 12. A unit according to claim 9 or 10 wherein the blocking element is movable from a non blocking position to a blocking position with an elastic deformation of the blocking element. 12 13. A unit according to any one of claims 9 to 12 wherein means are provided to retain the blocking element in the blocking position. - 14. A unit according to claim 13 wherein the means to retain the blocking element in position comprise a protrusion on the tongue, said protrusion having a face adapted to be engaged by the blocking element, when in the blocking position, to retain the blocking element in the blocking position. 15. A unit according to any one of the preceding claims wherein the plate or housing is of metal. 16. An airbag unit substantially as herein described with reference to, and as shown in, Figures I to 5 of the accompanying drawings. 17. An airbag unit substantially as herein described with reference to, and as shown in, Figures 6 and 7 of the accompanying drawings. 18. An airbag unit substantially as herein described with reference to, and as shown in, Figure 8 of the accompanying drawings 19. An airbag unit substantially as herein described with reference to, and as shown in, Figure 9 of the accompanying drawings. 20. Any novel feature or combination of features disclosed herein. Amendments to the claims have been filed as follows CLAIMS:

1. An airbag unit comprising a mounting plate or housing, and a cover mounted on the plate or housing, the cover and the plate or housing defining a chamber containing an airbag, the cover having sidewalls located adjacent the periphery of the plate or housing, the sidewalls being provided with resilient tongues, each tongue extending generally parallel with the adjacent sidewall, each tongue being provided with a first abutment, being an aperture or recess in the resilient finger, adapted to be brought into co-operating engagement with a cooperating second abutment, being a protrusion directed towards the centre of the plate or housing, which is formed on the mounting plate or housing, by a movement of the resilient tongue outwardly away from the centre of the mounting plate or housing to secure the cover to the mounting plate or housing.

2. A unit according to claim I wherein said tongues are integral parts of the cover.

3. A unit according to claim I or 2 wherein the cover is made of a polymer with resilient properties.

4. A unit according to any one of the preceding claims wherein the second abutment is a tongue forTned on the plate or housing at one edge of an aperture through which the resilient finger passes.

5. A unit according to any one of the preceding claims wherein each finger is associated with a blockina element, the blocking element being adapted to 0 engage the finger and retain the finger in the position in which the abutments engage.

6. A unit according to claim 5 wherein the blocking element is formed integrally with the plate or housing.

7. A unit according to claim 6 wherein the blocking element is in the form of a tab extending from one side of an aperture formed in the plate or housing.

8. A unit according to claim 6 or 7 wherein the blocking element is movable from a non-blocking position to a blocking position with a plastic deformation of the blocking element.

9. A unit according to claim 6 or 7 wherein the blocking element is movable I from a non blocking position to a blocking position with an elastic deformation of the blocking element.

10. A unit according to any one of claims 6 to 9 wherein means are provided to retain the blocking element in the blocking position.

11. A unit according to claim 10 wherein the means to retain the blocking element in position comprise a protrusion on the tongue, said protrusion having C a face adapted to be engaged by the blocking element, when in the blocking position, to retain the blocking element in the blocking position.

12. A unit according to any one of the preceding claims wherein the plate or housing is of metal.

13. An airbag unit substantially as herein described with reference to, and as shown in, Figures I to 5 of the accompanying drawings.

14. An airbag unit substantially as herein described with reference to, and as shown in, Figures 6 and7 of the accompanying drawings. -

15. An airbag unit substantially as herein described with reference to, and as shown in, Figure 8 of the accompanying drawings I