Inflatable protective cushion to cover the side panes of a vehicle

[0002] The invention relates to an inflatable protective cushion to cover the side panes of a vehicle in the event of a side impact, having a front end and a frontal anchor point in an area of the A-column and a rear anchor point in an area of the C-column of the vehicle, and having a gas distribution tube substantially extending between the A- and C-columns of the vehicle and connected to a gas generator.

[0003] Such a protective cushion is stowed in the folded state along the lower roof edge within the vehicle. On account of the curved shape of the roof edge, the lower edge of the protective cushion must have a greater length than the straight connecting line between the two anchor points. When the protective cushion becomes activated, automatic shortening of its lower edge occurs due to the expansion of the protective cushion in transverse direction to the connecting line between the anchor points. In its activated state, the protective cushion is therefore stretched along its lower edge. However, after the gas pressure inside the protective cushion has decreased, the tension along its lower edge is lost. But in the event of the vehicle overturning, the protective action by the protective cushion is desired, by it acting as a protective curtain. The protective cushion cannot fulfill this function adequately when it is not under tension along its lower edge.

[0004] By the invention, a protective cushion of the type initially mentioned is further developed in the aspect that, on activation of the protective cushion, it is tensioned along its lower edge with the tension remaining effective even after the pressure in the protective cushion has decreased. According to the invention this is achieved in that the gas distribution tube has an end with a piston slidably accommodated therein, having a piston rod connected to the piston protruding from the end of the gas distribution tube, one of the anchor points being provided on a free end of the piston rod.

[0005] On activation of the protective cushion, the piston, and with it the piston rod, is pushed out of the front end of the gas distribution tube, causing the frontal anchor point of the protective cushion to be displaced towards the front. This means that the effective length of the line between the two anchor points is increased. The protective cushion is now tensioned along its lower edge between the two anchor points, independently of a shortening of the protective cushion which will occur when it becomes inflated. The tensioning of the protective cushion remains effective even after its relaxation.

[0006] According to a preferred embodiment, which is favored by the interior design of modern vehicles, the piston rod is inclined at an acute angle with respect to the straight line defined by the anchor points. With this embodiment there is no need for a separate back stop for both the piston and the piston rod, because the piston rod is clamped in the front end of the gas distribution tube, due to the traction exerted along the lower edge of the protective cushion.

[0007] Further advantages and characteristics of the invention read from the following description of a preferred embodiment and the drawing referred to, in which

[0008] FIG. 1 shows a schematic general view of an activated protective cushion in a vehicle; and

[0009] FIG. 2 shows an enlarged detail view of the area marked by a frame X in FIG. 1.

[0010] FIG. 3 shows an enlarged detail view of the area marked by a frame X in FIG. 1, according to an advantageous embodiment.

[0011] The protective cushion, generally given the designation 10 in the illustrations, is designed to cover the side pane of a vehicle in the event of a side impact or when the vehicle overturns, and extends from a frontal anchor point 12 at the A-column to a rear anchor point 14 at the C-column of the vehicle. A gas generator 16 is furthermore arranged at the C-column, from which a gas distribution tube 18 leads into the interior of the protective cushion 10. In its activated state, the protective cushion 10 forms a curtain which covers the side panes of the vehicle as well as the middle B column. As illustrated in FIG. 1, not the entire surface of the protective cushion is inflatable; the frontal end portion of the protective cushion, adjoining the anchor point 12, is not inflatable.

[0012] As illustrated in FIG. 2, the gas distribution tube 18 leaves the protective cushion 10 at its front end and is extended forward to the frontal anchor point 12. A slidable piston 20 is inserted into the front end of the gas distribution tube 18 and a piston rod 22, rigidly connected to the piston 20, protrudes from the end of the gas distribution tube 18. This end of the gas distribution tube 18 is flanged inwards and so forms a stop for the piston 20. The free end of the piston rod 22 is provided with an eye 24 which is connected to a tensioning strap 26, sewn on the front end of the protective cushion 10. The flow cross section of the gas distribution tube 18 is reduced by a gas deflection ramp 28 before it leaves the protective cushion 10. The diameter of the gas distribution tube 18 is also reduced at its front end. In its advantageous embodiment, as illustrated in FIG. 3, the gas distribution tube 18 is extended at its front end by an insert tube which is inserted into the gas distribution tube 18 and has a cross section with a lower diameter than that of the gas distribution tube 18.

[0013] For activating the protective cushion, the gas generator 16 is ignited. The compressed gases supplied by the gas generator 16 are fed into the inflatable part of the protective cushion 10 by way of the gas distribution tube 18. At the same time, the pressure produced acts upon the inner end face of the piston 20, whereby the piston with its piston rod 22 is pushed forwards until it meets the stop provided by the flanged end at the front end of the gas distribution tube 18. Together with the piston rod 22, the eye 24 is also displaced in a forward direction, whereby the distance between the anchor points 12, 14 is increased and the lower edge of the protective cushion 10 is correspondingly tensioned. Since the piston rod 22 is at an acute angle with respect to the straight line between the anchor points 12, 14, the piston 20 is clamped at the frontal end of the gas distribution tube 18 by the traction force produced so that a back stop becomes unnecessary.