Airbag comprising two chambers and a gas flow channel connecting the two chambers with a valve being located in the gas flow channel

An airbag includes a first chamber, a second chamber, and a gas flow channel connecting the two chambers. A valve is located inside the gas flow channel allows an unthrottled gas stream from the first chamber to the second chamber when a pressure inside the first chamber is higher than a pressure in the second chamber and blocks or throttles the gas stream through the gas flow channel when the pressure inside the second chamber is higher than in the first chamber. The valve includes a two-layered inlay extending from a first end pointing towards the first chamber to a second end pointing towards the second chamber. The two-layered inlay is connected to the gas flow channel at its first end via at least two connecting points being remote from each other. In order to make the manufacture of the airbag very easy and in order to provide a construction that allows the possibility of a defined throttling of the gas flow in the gas flow direction opposite to the unthrottled gas flow direction, a connection free area in which at least one layer of the two-layered inlay is without connection to the gas flow channel, is provided between the two connecting points and the two layers of the two-layered inlay are at least partially connected to each other in the area of the first end.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 371 U.S. National Stage of International Application No. PCT/SE2012/051450, filed Dec. 20, 2012, and published in English as WO 2013/095283 Al on Jun. 27, 2013, which claims priority to German Patent Application No. 102011011464.9, filed Dec. 24, 2011. The entire disclosures of the above applications are incorporated by reference herein.

TECHNICAL FIELD OF THE INVENTION

The invention is concerned with an airbag comprising two chambers being connected by a gas flow channel and a valve being located in said gas flow channel.

Especially from so-called curtain airbags it is known to provide two chambers serving for the protection of the passengers, wherein the two chambers are connected via a hose type gas flow channel. For example, the first chamber serves for protecting a passenger in the front and the second chamber serves for protecting a passenger in the rear of the vehicle.

In some applications it can be desired to provide a one way valve in the gas flow channel such that gas can stream unthrottled through the gas flow channel if the pressure inside the first chamber is higher than the pressure in the second chamber, but the gas stream through the gas flow channel is blocked or at least throttled if the pressure in the second chamber is larger than in the first chamber.

PRIOR ART

Such a valve is described in the generic U.S. Pat. No. 6,402,190 B1. Here, a two-layered inlay is provided inside the gas flow channel. A circumferential seam is provided at one end of the inlay which connects the two layers of the inlay to the two side walls of the gas flow channel. So, gas can stream unthrottled from the first end of the valve to its second end. In this case the two-layered inlay is inflated towards the side walls of the gas flow channel. In the opposite case the two-layered inlay collapses and blocks the gas flow.

A similar concept is shown in the DE 10 2009 005 834 A1.

SUMMARY OF THE INVENTION

Starting from this the invention sets itself the problem to improve the valve of a generic airbag. Especially the manufacture of the airbag should be very easy and the valve should be constructed in a way that allows the possibility of a defined throttling of the gas flow in the gas flow direction opposite to the unthrottled gas flow direction.

This problem is solved by an airbag according to claim1.

As in the generic U.S. Pat. No. 6,402,190 B1 the valve is comprised of a two-layered inlay extending from a first end pointing towards the first chamber to a second end pointing towards the second chamber. But in contrast to the prior art, there is no circumferential seam such that a connection free area exists in which at least one layer of the two-layered inlay is not connected to the gas flow channel. Further, the two layers of the two-layered inlay are at least partially connected to each other in the area of the first end. Consequently, the gas flows between at least one layer of the two layered inlay and a side wall of the gas flow channel when flowing from the first to the second chamber, instead between the two layers of the two-layered inlay as is the case in the prior art.

As one will see from the description of the preferred embodiments, the assembly of the airbag is very easy and the additional work necessary in relation to an airbag without a valve is very minor. Additionally, one will see that it is very easy to “tune” the valve such that in the blocking/throttling direction a defined throttled gas flow can pass through the valve.

The invention will now be explained in detail by means of preferred embodiments in view of the accompanying figures. The figures show:

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1shows a curtain airbag10in a schematic representation. The curtain airbag10comprises a first chamber12that may be assigned to a front seated passenger and a second chamber14that may be assigned to a passenger in the rear of a motor vehicle. The two chambers12,14are connected via a hose-type gas flow channel16. An accommodation area18for a gas generator (not shown) extends from the gas flow channel16as is well known in the art. A no-return valve20is located inside the gas flow channel16in an area between the accommodation area18and the second chamber14. This no-return valve20acts such that gas can flow unthrottled into the second chamber14, but not back. The construction of this no-return valve20and its way of operation will be described later in detail.

As can be seen fromFIG. 2, the curtain airbag10is comprised of only three parts, namely a first cutting30, a second cutting32and a third cutting34. Of course, there may be more parts such as positioning tethers and attachment lugs, but since these elements are not necessary in order to understand the invention they are not shown. The first cutting30and the second cutting32are congruent and form the side walls of the curtain airbag10. The third cutting34is a rectangle and forms the no-return valve20. The assembly of the three parts is very easy: First, the third cutting34is folded in half as is shown inFIG. 2and positioned on the respective gas flow channel area of the first cutting30. Then, the second cutting32is positioned on the first cutting and the cuttings are sewn together with the edge seam36. So, one can see that the effort necessary for the assembly of the curtain airbag10is not higher than for a curtain airbag without a valve.

TheFIGS. 3, 3aand3bshow the detail D ofFIG. 1in various views. One sees a section of the hose-type gas flow channel16having a first side wall16aand a second side wall16b. Inside this gas flow channel16there is the valve20that is in form of a two-layered inlay made by the folded third cutting34. So, this two-layered inlay has a first layer21and a second layer22. The two layers21,22are connected to each other via the fold23at the first end of the two-layered inlay. This first end points towards the first chamber12. The first end of the two-layered inlay is connected to the gas flow channel16(namely its two side walls16a,16b) at two points, namely at its lower end and at its upper end, via the two closing lines17a,17bof the gas flow channel16. The two closing lines17a,17bare sections of the edge seam36in this embodiment. In this preferred embodiment the upper end and the lower end of the two-layered inlay are connected to the side walls of the gas flow channel along its entire length, but this might not be necessary in all possible embodiments. In the preferred embodiment shown, the two closing lines17a,17bof the gas flow channel have two functions: First, they close the gas flow channel and second, they serve as connecting lines between the two-layered inlay and the side walls of the gas flow channel.

One can see that the two layers21,22of the two-layered inlay of the valve are not connected to the side walls of the gas flow channel16between the closing lines17a,17b, which also constitute the connecting lines between the two-layered inlay and the gas flow channel16. So, there exists a connection free area, in which both layers21,22of the two-layered inlay are not connected to the side walls of the gas flow channel16.

If the pressure inside the first chamber12is higher than in the second chamber14, gas flows through the gas flow channel16and passes the valve20unthrottled, namely between the first layer21of the two-layered inlay and the first side wall16aof the gas flow channel and between the second layer22of the two-layered inlay and the second side wall16bof the gas flow channel16. By doing so, the two layers of the two-layered inlay are pressed together. Of course, there is a slight throttling due to a slightly higher flow resistance, but in the definitions chosen here, this state is referred to as being unthrottled.

In the other case, this is if the gas pressure inside the second chamber14is higher than in the first chamber12(this can for example occur, if a vehicle passenger in the rear of the vehicle hits the second chamber14, but the first chamber12is not hit by a passenger) the valve being formed of the two-layered inlay blocks the gas flow as is shown inFIGS. 4, 4aand4b. Gas enters the space between the two layers21,22but cannot escape, because the first end is closed by the fold23. So, the pressure between the two layers rises and presses the two layers outwardly towards the side walls16a,16band closes the valve. This works very reliably.

TheFIGS. 5, 5aand5bshow a second embodiment of the invention in a representation according toFIGS. 4, 4aand4b. Here, the valve allows a throttled gas flow from the second chamber to the first chamber. In order to achieve this, at least one hole (here two holes25a,25b) is provided in the fold23at the first end of the two-layered inlay. So, a clearly defined gas stream can pass through the valve in the direction opposite of the unthrottled passing direction. The amount of the gas flow can precisely be tuned by the choice of the total cross section of the holes. The assembly of the curtain airbag is as easy as in the first embodiment.

TheFIGS. 6 and 7show an embodiment which is very similar to the one which is shown inFIGS. 3 to 4. The difference is that the first layer21of the two-layered inlay is additionally connected to the first side wall16aby means of a first positioning seam40a. This first positioning seam40ais located at the second end of the two-layered inlay (this is the end remote from the fold23). This first positioning seam40ais basically located in the middle of the height of the first layer21. The same applies to the second layer22: The second layer22is at its second end additionally connected to the second side wall16bby means of a second positioning seam40b. By this positioning seams40a,40b, four “sub-channels” are defined in the passing state of the valve as is shown inFIG. 6.

The advantage of the presence of the positioning seams40a,40bis that in the passing state (FIG. 6) there is no risk the fold23bulges inwardly which could lead to an undesired blocking or partial blocking of the gas flow and that in the blocking state (FIG. 7), the second end of the two-layered inlay is already open at the beginning of the blocking of the gas flow, which leads to an immediate reaction.

TheFIGS. 8 and 9show a variant of the embodiment just described: Here, the positioning seams40a, and40bare positioned at an upper position.

Although not shown in the figures, it is possible to combine the embodiment shown inFIGS. 5 to 5b(at least one hole in the area of the first end) with the embodiment shown inFIGS. 6 to 9(positioning seams).

FIGS. 10 to 12show another embodiment of the invention: Here, a stiffening seam42is provided next to the fold23and extending basically parallel to the same. This stiffening seam42especially prevents the first end of the two layered inlay from bulging inwardly in the passing state.

The invention has been described by ways of a curtain airbag which is the preferred application, but it should be pointed out that the invention might also be applied to other types of airbags, especially to seat mounted or car body/door mounted side airbags.

LIST OF REFERENCE NUMBERS

16gas flow channel

16afirst side wall

16bsecond side wall

17afirst closing line

17bsecond closing line

18accommodation area for gas generator