WO2007016972A1

WO2007016972A1 - Airbag with externally closable venting openings

Info

Publication number: WO2007016972A1
Application number: PCT/EP2005/053670
Authority: WO
Inventors: Azucena Pérez García
Original assignee: Dalphi Metal España, S.A.
Priority date: 2005-07-27
Filing date: 2005-07-27
Publication date: 2007-02-15

Abstract

An airbag having a venting area comprising one or several gas venting openings (13) and at least one instrumental opening (17) provided with a closing element (23, 33, 43, 53) made at least partially of a resilient material, which is configured to begin to deform when the internal pressure of the bag reaches a predetermined level, said venting openings (13) and instrumental opening (17) being located and configured such that said deformation of the closing element (23, 33, 43, 53) allows to partially or completely close said venting openings (13) when the internal pressure of the bag (11) exceeds predetermined levels (P2, P3), respectively.

Description

AIRBAG WITH EXTERNALLY CLOSABLE VENTING OPENINGS

FIELD OF THE INVENTION

The present invention refers to airbag venting devices used in automobiles to absorb blows experienced by drivers and passengers in the event of crashes or collisions.

BACKGROUND OF THE INVENTION

Airbags basically consist of a folded bag that is quickly inflated by means of a gas produced by a generator when certain sensing devices detect a collision of the vehicle. The bag is thus deployed in front of the driver or a passenger, depending on their location, and prevents their bodies from hitting against any area of the vehicle.

In normal deployment operation of the bag the internal pressure produced by the generator when it is filled with gas can be high enough to cause the bag to be so hard that the occupant bounces off. To prevent this drawback they have been provided with a venting opening useful for reducing the internal pressure of the bag and, accordingly, the possibility of causing damage when they are actuated.

The use of different means of blocking this venting opening is in turn known for achieving better control of the internal pressure in the bag than that provided by only the variation of the size of the opening. In this sense the use of patches for achieving that the gas does not immediately exit through the discharge opening but when the patch breaks when a given pressure inside the bag is reached can be highlighted. The art has proposed different types of patches with different means for controlling their breaking more or less according to a given resistance to the gas pressure inside the bag. Thus the presence of the gas pressure required for the bag to perform its protective function is made compatible with the assurance that the gas pressure will not reach an excessive value with a risk for people over whom the bag is deployed.

On the other hand, the need has also arisen for venting devices that allow to increase the gas outflow according to the specific characteristics of each collision and of the type of passenger affected, and in this sense different venting device solutions are also known providing venting openings of adjustable surface facilitating the increase of the venting area as the internal pressure in the bag increases. A newly arisen need poses the need for airbags that allow to reduce the venting area, even completely eliminating it, under certain impact conditions, which requires closing mechanisms that must operate opposite to the art known until now. The previously mentioned traditional patches had to completely cover the outlet opening until the internal pressure of the gas in the bag did not reach a certain level and after that they broke, ceasing to work; now the opposite is required: devices that allow to close the venting opening when it is already open when the internal pressure of the bag reaches certain levels.

In these respect, some proposals are known, such as those disclosed in patent ES 2182629, patent US 6139048 and patent application US 2004/0090054, which use movable elements for closing the venting opening, using the stresses caused in the bag due to the difference of pressure together with the difference in form of occupant load. The present invention proposes a solution in these respect based on different principles.

SUMMARY OF THE INVENTION

The objective of the present invention is to achieve an airbag with a closable venting device which for high severity condition collisions allows the partial or complete closing of the venting opening after a first phase in which it is open evacuating gas.

This objective is achieved by providing the bag, in addition to one or several gas venting openings, with an instrumental opening provided with a closing element made at least partially of a resilient material that is configured to begin to deform when the internal pressure of the bag reaches a predetermined level, the venting openings and the instrumental opening being located such that said deformation of the closing element allows to partially or completely close the venting openings when the internal pressure of the bag exceeds predetermined limits.

One advantage of the present invention is that the venting device operation depends only on the internal pressure of the bag, which is very interesting given the possibilities of controlling this variable. The final produce is stronger since it does not depend on other features such as stresses/deformations. Another advantage of the present invention is that the internal pressure of the bag is more stable as a control parameter of the venting device operation than other parameters depending on factors such as the way the bag is deployed or the occupant placement with respect to the bag.

Another advantage of the present invention is that it provides both the complete closing of the venting opening of the bag and the partial closing for those cases of intermediate severity between the major and minor impact severity conditions.

Other features and advantages of the present invention will emerge from the following detailed description of an illustrative and by no means limiting embodiment of its object in relation to the attached drawings.

DESCRIPTION OF THE DRAWINGS

Figure 1 shows a schematic elevational view of the venting area of an airbag according to the present invention.

Figure 2 shows a schematic plan view of the venting area of an airbag according to the present invention.

Figure 3 shows a schematic elevational view of the venting area of an airbag according to the present invention in the state corresponding to a low severity impact.

Figure 4 shows a schematic elevational view of the venting area of an airbag according to the present invention in the state corresponding to an intermediate severity impact.

Figure 5 shows a schematic elevational view of the venting device according to the present invention in the state corresponding to a high severity impact.

Figures 6, 8, and 9 show plan views of a venting area of an airbag according to the invention with a closing element made with a resilient portion and a less resilient portion, of a different configuration in each case. Figure 7 shows a schematic elevational view of the venting area of Figure 6.

DETAILED DESCRIPTION OF THE INVENTION

According to a first embodiment of the present invention, to which

Figures 1-5 correspond, the venting area of the bag 11 includes several venting openings 13 that may be provided or not with a membrane 15 and an instrumental opening 17 provided with a closing element 23, adhesive elements 19 being used for this purpose.

The group of venting openings 13 has an area A sized in order to achieve a sufficient evacuation of the gas under general airbag operating conditions since the closing element 23 will only operate in exceptional cases.

The closing element 23 is formed by a laminar part 25 with portions of different thickness, made of a resilient material, preferably silicone, and by a part 27 made of a less resilient material, preferably the same fabric as the bag

11 , both parts being joined by means of suitable means such as adhesion or over-injection. The least resilient part 27 limits the deformability of the resilient part 25 in the common area and, by being located in the center, it directs the deformation of the resilient part 25 towards the areas occupied by the openings

13.

The closing element 23 could also be made only of a resilient material, the desired deformation being controlled by means of different thickness.

Under the less severe impact conditions, there will be a given internal pressure P1 inside the bag 11 that will cause the membranes 15 to break but will not deform the closing element 23, which remains at rest so to speak, as can be observed in Figure 3.

Under intermediate severity impact conditions, there will be a greater internal pressure inside the bag than in the previous cases, called P2, and as a result it will be necessary to evacuate a smaller amount of gas, which is achieved by means of the partial closing of the venting openings 13 upon closing element 23 being partially deformed as a result of pressure P2, as can be observed in Figure 4.

Under higher severity impact conditions, a greater internal pressure is produced inside the bag than in the previous cases, called P3, which causes deformation of the closing element 23 partially blocking the venting openings 13 preventing the gas of the bag from exiting, as can be seen in Figure 5.

Figures 6-7 show a second embodiment of the invention with a venting area in which the venting openings 13 are on one side of the instrumental opening 17. The closing element 33 is formed by a resilient portion 35 and a less resilient portion 37, sized according to said locations.

Figure 8 shows a third embodiment of the invention with a venting area with four venting openings 13 arranged equidistantly on the outside of the instrumental opening 17. The closing element 43 is formed by a resilient portion 45 and a less resilient portion 47, sized according to said locations.

Figure 9 shows a fourth embodiment of the invention with a venting area with two non-circular shaped venting openings 13 and a closing element 53 formed by a resilient portion 55 and a less resilient portion 57. Although several embodiments of the invention have been described and represented, modifications comprised within the scope thereof can be introduced in it, the invention not being considered limited to said embodiments but to the content of the following claims.

Claims

1. An airbag the inflatable bag (11 ) of which comprises one or several gas venting openings (13), characterized in that a) the venting area of the bag where the venting openings (13) are located also comprises at least one instrumental opening (17) provided with a closing element (23, 33, 43, 53) made at least partially of a resilient material, which is configured to begin to deform when the internal pressure of the bag reaches a predetermined level; b) the venting openings (13) and the instrumental opening (17) are located and configured such that said deformation of the closing element (23, 33, 43, 53) allows to partially or completely close said venting openings (13) when the internal pressure of the bag (11 ) exceeds predetermined levels (P2, P3), respectively.

2. An airbag according to claim 1 , characterized in that the venting openings (13) are provided with membranes (15) configured to break when the internal pressure of the bag (11 ) exceeds a predetermined limit (P1 ), lower than the predetermined limits (P2, P3), that allow the closing element (23, 33, 43, 53) to partially or completely close said venting openings (13).

3.- An airbag according to claims 1 or 2, characterized in that the closing element (23, 33, 43, 53) is made with two materials of different resilience.

4.- An airbag according to claim 3, characterized in that the closing element (23) comprises a resilient part (25) occupying the entire instrumental opening (17), and a less resilient part (27) of a smaller dimension joined to it to limit its deformation in the common area.

5.- An airbag according to claim 3, characterized in that the closing element (33, 43, 53) is formed by a resilient portion (35, 45, 55) and a less resilient portion (37, 47, 57), sized such that the deformation of the resilient portion (35, 45, 55) can close the venting openings (13).

6.- An airbag according to claims 3-5, characterized in that the two portions (25, 27; 35, 37; 45, 47; 55, 57) of the closing element (23, 33, 43, 53) are joined either by adhesion or by over-injection.