Patent Application
20090058051
The present invention relates generally to a curtain airbag for installation into a motor vehicle, especially for installation into a passenger car. Particularly the invention relates to a curtain airbag having at least two gas chambers being connected by a tube made of a flexible material extending between a first and a second gas chamber.
Curtain airbags are widely used in passenger cars. In a mounted and non-inflated state such a curtain airbag is fixed to the inner structure of the car in the area of the roof bar and extends in general along the entire roof bar. In inflated state the curtain airbag covers the side-windows and (if present) the B-pillar. In general it is not necessary that gas chambers are provided along the whole area of the side-windows. It is known to provide at least two gas chambers which are separated from one another by a non-inflatable intermediate section. In this case a first gas chamber is assigned to the front passenger or driver and the second gas chamber is assigned to the rear passenger. For larger vehicles with three seat rows it known to provide a third gas chamber for the third seat row.
Often, the curtain airbag is made of a single material, namely a woven plastic material. In order to achieve the desired gas tightness this woven material must be rather thick or coated which makes the curtain airbag heavy and expensive.
From U.S. Pat. No. 6,883,827 it is known to provide a curtain airbag with separate sections each having a gas chamber. Said sections are connected by tube elements and flexible straps. The tube elements serve for filling all gas chambers by a single gas generator and the straps serve for keeping the whole curtain airbag in position. Consequently, there exist hollow spaces between the sections and there is the risk that during an accident body parts of a passengers or the driver come into a position outside the car if the side windows are open.
From the WO 2006/74814 A1 a similar curtain airbag is known. Here, a non-inflatable intermediate section with a large surface is disposed between a first and a second section. Nevertheless there is a risk that a body part, especially an arm penetrates between the non-inflatable intermediate section and the tube connecting first and the second gas chamber. Further, this curtain airbag is rather complicated to manufacture.
Given the foregoing, it would be desirable to provide a curtain airbag that protects body parts securely from coming into a position outside the car, which is of light weight, and which is easy and of low cost to manufacture.
The present invention relates to an improved curtain airbag that is of light weight, that is low cost and easy to manufacture and that protects securely body parts from coming into a position outside the car, so called ejection mitigation.
The curtain airbag of the present invention comprises a first section having two side walls enclosing a first gas chamber and a second section having two side walls and enclosing a second gas chamber. A tube made of a flexible material extends between these two sections and connects the first gas chamber with the second gas chamber. A non-inflatable intermediate section connects the first and the second section and is sewn to the first section by a first seam and to the second section by a second seam. Further, said non-inflatable intermediate section is sewn to the tube by a third seam. Consequently, it is possible to select a suitable material for each functional part. Especially for the first and the second section as well as for the tube, a gas tight and rather heavy material can be chosen while for the non-inflatable intermediate section a light weight and less expensive material is preferred. Nevertheless, the inflated airbag constitutes a closed surface so that no body parts can project through this curtain airbag.
In a preferred embodiment the tube is being made of at least one cutting and being closed by at least one tube closing seam. Manufacturing that tube from a cutting makes the manufacture easy and cost effective. Especially the material of said cutting can be the same material as the material the first and the second section are made from. Even more preferred the third seam connecting the non-inflatable intermediate section and the tube closing seam are the same seam. This helps making the manufacture cost effective and easy. Even more preferred first seam, second seam and third seam are sections of a single seam that can be sewn in a single step.
Often, it is preferred that the first and second gas chamber are filled simultaneously and not one after the other. In order to achieve this, the gas generator must be placed between these two gas chambers, this is between first and second section of the curtain airbag. So, in a further preferred embodiment a receiving section for receiving a gas generator extends from the tube. Even more preferred said receiving section and said tube are made of a single cutting leading to a high degree of integrity and gas tightness. Still further preferred this cutting is H-shaped. In order to protect that cutting from gas streaming out of the gas generator a reinforcement layer can be provided.
In an alternative embodiment the tube for the cutting is not H-shaped. Here it is of rectangular shape and shows a longitudinal slit. This slit is necessary in order to achieve an easy assembly as will be described later in greater detail. If in this case a gas generator is to be attached to the tube a separate receiving cutting is provided and attached to a non-flit area of the tube. Said receiving cutting is forming the receiving section.
In both cases the tube shows an open longitudinal edge in a pre-assembled state. In order to achieve an easy manufacturing process this open longitudinal edge is closed after the tube has been connected to the first and the second section.
The invention will now be described in detail by ways of preferred embodiments in view of the attached figures. In the figures:
a shows how the tube is being sewn to the first section;
b shows a sectional view along line I-I of
An intermediate section 40 is provided for connecting first and second section 20, 30. Said intermediate section 40 does not comprise a gas chamber, consequently it only needs a single layer. Preferably, this intermediate section 40 is made of a light material, for example a foil or uncoated light fabric.
In assembled state the two gas chambers 21, 31 are connected via a tube. In this embodiment a receiving section extends from this tube. This tube and receiving section are made from a H-shaped cutting 54 and a reinforcement layer 56. The assembly of the tube is now explained:
As shown in
In a next step, the tube 50 is connected to the first and the second section 20, 30. This connection is made by tube connecting seams 69. Since one longitudinal edge, namely the lower edge 54b, of tube 50 and the middle edges 24, 34 of first and second section 20, 30 are open at this stage of assembly, it is easy to apply these seams 69. They can be sewn in a flat position as shown in
In a last step, the connecting and closing seam 70 is applied. This connecting and closing seam 70 has three sections namely the first seam section 70a, the second seam section 70c and the third seam section 70b. The first seam section 70a closes the open middle edge 24 of first section 20 and connects the intermediate section 40 to said first section. The third seam section 70b closes the lower edge of tube 50—therefore it is the tube-closing seam—and connects the intermediate section 40 to said tube 50. Finally, the second seam section 70c closes the open middle edge 34 of second section 30 and connects the intermediate section 40 to said second section (
The
As is shown in
Now, the sub-assembly as shown in
In the following steps the curtain airbag is finished: First, the seams 95 connecting the additional cutting the rectangular cutting 64 and the side walls 30a, 30b are sewn. Second, the tube connecting seams 69 are added in the same way as in the first embodiment. Since the lower edge 54b of the tube 50 is open at this stage, The tube closing seams 69 can be sewn in a “flat condition” similarly as shown in
Finally, a connecting and closing seam 70 as shown as in the first embodiment is added. The first seam section 70a connects the first section 20 to the intermediate section 40, closing seam section 70b closed the tube 50 and connects intermediate section 40 to the tube 50 and second seam section 70c connects the intermediate section 40 to the second section 30.
The seams can be sewn seams or other seams, like welded seams. If sewn seams are used, it might be necessary to take additional measures in order to achieve a higher gas-tightness, depending on the application. If the curtain airbag is only for protection during a side impact, there is generally no need for additional gas-tightening. If, however the curtain airbag is also for protection during a roll-over accident, the curtain airbag must keep its pressure for up to six seconds. In this case, sewn seams need sealing. Such a sealing can be provided in form of an adhesive applied between the material layers before sewing or on the outside after sewing. Especially silicone can be used as an adhesive.
