Gas bag with valve

Abstract

A gasbag has a discharge opening (14) in an outer wall (12) which is covered by a valve (16). The valve (16) comprises at least two flexible valve elements (18) arranged side by side along a circumferential edge (20) of the discharge opening (14). Each valve element (18) has an outer edge (22) that is arranged at the circumferential edge (20) of the discharge opening (14) and is fixed there at least partially. Each valve element (18) has a surface section (28) that extends from the circumferential edge (20) into the surface of the discharge opening (14) and terminates in an inner edge (24) in the region of the discharge opening (14). The surface sections (28) are not fixed to one another at least partially in the region of the discharge opening (14) and are movable perpendicular to the surface of the discharge opening (14), so that the discharge opening (14) has a variable gas flow. The surface sections (28) of adjacent valve elements (18) overlap section by section.

Description

The invention relates to an airbag having a valve, in particular for a vehicle occupant protection system.In order to protect a vehicle occupant, airbags are filled with a high gas pressure in a short time. However, the optimum protective effect of an airbag is also dependent on its internal pressure. For example, a gas bag with a high internal pressure is often more favorable for a large, heavy vehicle occupant, while a gas bag with a lower internal pressure can develop the better protective effect for a small, light vehicle occupant. Different distances of the vehicle occupant from the airbag can also be better compensated by adapting the internal pressure. Likewise, in the case of airbags that can be filled with different volumes, a volume-independent internal pressure can be set.The adaptation of the internal pressure should be carried out as simply as possible, which is why passive valves are advantageous. These are valves which open and close purely under the control of the internal pressure and do not comprise any further mechanical, electrical or pyrotechnic actuating mechanisms.It is the object of the invention to create an airbag with a passive valve that is simple to manufacture and cost-effective.This object is achieved by a gas bag having an outflow opening in an outer wall, wherein the outflow opening is covered by a valve which comprises at least two flexible valve elements which are arranged next to one another along a circumferential edge of the outflow opening. Each valve element has an outer edge which is arranged on the circumferential edge of the outflow opening and is firmly fixed there at least in sections. In addition, each valve element has a surface section which extends from the circumferential edge into the surface of the outflow opening and ends in an inner edge in the region of the outflow opening. The surface sections are at least partially unfixed to each other in the region of the outflow opening. The surface sections are also movable perpendicular to the surface of the outflow opening, so that the outflow opening has a variable gas flow rate. The surface sections of adjacent valve elements overlap in sections.This results in an arrangement of overlapping valve elements around the outflow opening. In particular, the valve elements can be arranged in the form of a scale or iris around the outflow opening.The higher the internal pressure in the airbag, the more the surface sections of the valve elements are pressed outwards perpendicular to the surface of the outflow opening and the higher the gas flow through the now open valve. However, if the internal pressure in the airbag falls below a certain value, the valve elements are placed flat against one another and together close the surface of the outflow opening to a maximum degree. The valve is then closed. The valve is thus a pressure-adaptive passive valve.The overlapping of the individual valve elements brings about a labyrinth-like structure, which the gas must pass in order to pass out of the airbag through the outflow opening. The gas flow rate of the valve and its pressure dependence can be adjusted via the degree of overlap, the number, the shape and the rigidity of the valve elements.Preferably, adjacent valve elements overlap both on their outer edge and on their surface section and thus at least with a section of their inner edge.In addition to the valve elements, no further components are required for the valve, which makes production cost-effective and simple. In particular, the valve has neither tear seams nor tension elements.For the valve elements, for example, airbag fabric can be used.The single valve element may consist of a single fabric layer. In order to increase the rigidity, the single valve element can also consist of a plurality of identically shaped fabric layers which are placed one above the other and connected to one another, for example by adhesive bonding, welding or sewing.The use of a coating also allows the stiffness of the individual valve element to be increased.Preferably, all valve elements of a valve are identically constructed and shaped.The valve elements can be fastened along their entire outer edge to the circumferential edge of the outflow opening.In one variant, however, each valve element is fastened to the circumferential edge only along a partial section of its outer edge. This means that each valve element is also movable in at least one portion of its outer edge relative to the outer wall of the airbag and thus can fold the valve element further outwards with respect to the surface of the outflow opening.It is possible that the fastened subsection of the outer edge lies in the middle of the outer edge with respect to the circumference of the outflow opening and thus the valve element is movable on both sides of the fastened subsection with respect to the circumferential edge of the opening.The valve elements can be arranged in such a way that they together form an iris diaphragm arrangement in which the valve elements lie one above the other in a scale-like or roof-tile-like manner along the circumferential edge of the outflow opening. The valve elements can move relative to one another to a certain extent, except on the partial sections of the outer edge which are fixed along the circumferential edge of the outflow opening.Each valve element overlaps, for example, with exactly two adjacent valve elements, wherein preferably at least the plurality of valve elements is arranged one above the other in a scale-like or roof-tile-like manner along the circumferential edge of the outflow opening.Preferably, the subsection(s) of the outer edge resting directly on the circumferential edge of the outflow opening is fastened to the circumferential edge, while the subsection(s) of the outer edge resting on another valve element remain unfixed.A length of the circumferential edge fixed subsection of the outer edge of the valve element may be longer than a total length of the circumferential edge unfixed subsection or subsections, for example twice as long.The outer edge of each valve element may be longer than its inner edge.For example, 2 to 15, in particular 2, 3 or 4, valve elements are arranged around the circumferential edge of the outflow opening. These designs have proved suitable for being able to seal the outflow opening at the desired internal pressures in a substantially gas-tight manner when the valve is closed and for allowing a sufficient quantity of gas to escape in the open state.Above all, in the case of a circular outflow opening, the outer edge preferably extends in the form of a circular arc over an angle of 30° to 270°, in particular over 120°, 135°, 150°, 165° or 270°.The valve elements preferably have the shape of a segment of a circle or, more generally, the shape of a segment of the cross-sectional area of the outflow opening, even if this is not circular.The inner edge of the valve elements extends, for example, in two sections which meet at a bend. At a circumferential angle of the outer edge of less than 180°, the kink forms a tip. If the circumferential angle is greater than 180°, the bend lies in a recess. The bend corresponds in particular to the point of the valve element which, in the case of a circular outflow opening, is radially closest to the center point of the outflow opening.In one variant, both sections of the inner edge run in a straight line, which, in the case of a circular segment-shaped valve element, has the result that the inner edge sections lie along a radius of the outflow opening. In another variant, at least one of the sections of the inner edge extends concavely curved from the outer edge to the bend.The valve elements can be shaped and arranged, for example, in such a way that there is a point on the surface of the outflow opening beyond which none of the surface sections protrudes radially. In the case of a circular outflow opening, this is preferably the center of the circle which is only touched by all surface sections. At the center of the surface of the outflow opening, all valve elements can then move the freest.It is also conceivable to shape and arrange the valve elements in such a way that a region is provided at the center of the surface of the outflow opening, which region is not covered by any valve element, so that a small surface is permanently available as an outflow opening. This can be advantageous, for example, in order to facilitate the outflow of the gas from the airbag to the end of the intended service life.According to another variant, all valve elements are connected to one another by means of a circumferential fixing in the surface sections. This fixing, which is in particular a seam, restricts the movement of the valve elements perpendicular to the surface of the outflow opening and thus restricts the gas outlet. This embodiment is therefore particularly suitable for higher intended internal pressures.The fixing preferably runs concentrically to the edge of the outflow opening, preferably close to the center of the outflow opening, in order to be able to restrict the range of movement of the valve elements relatively greatly.In particular in this variant, it can also be advantageous if the valve elements have, at their radially innermost point, a bulge at which a plurality of valve elements overlap. This bulge can be used, for example, to fix the valve elements during the production of the circumferential fixing, but also to increase the flow resistance in the region of the center of the surface of the outflow opening.According to a further aspect, for stiffening the respective valve element, the surface section of at least one valve element can have a fixed fold running into the surface of the outflow opening.It would also be conceivable for this purpose to connect adjacent surface sections lying one above the other in sections with a radially extending fixing.The invention is described in more detail below with reference to several exemplary embodiments with reference to the attached figures. The figures show:FIG. 1 shows a schematic illustration of an airbag according to the invention with a valve according to a first variant;FIG. 2 is a schematic illustration of the components of the valve of FIG. 1 ;FIG. 3 shows a schematic illustration of a valve element of the valve from FIG. 1 ;FIG. 4 is a further schematic illustration of the valve from FIG. 1 ;FIG. 5 is a schematic sectional view taken along line V--V of FIG. 4;FIG. 6 is a schematic sectional view taken along the line VI-VI of FIG. 4;FIG. 7 shows a schematic illustration of the components of a valve of an airbag according to the invention according to a second variant;FIG. 8 shows a schematic illustration of a valve with valve elements according to FIG. 7 ;FIG. 9 is a schematic sectional view of the valve of FIG. 8 along the line IX--IX;FIG. 10 shows a schematic illustration of a valve element of the valve from FIG. 8 ;FIG. 11 is a schematic illustration of the valve of FIG. 8 from the opposite side;FIG. 12 is a schematic sectional view taken along the line XII-XII of FIG. 11 ;FIG. 13 shows a schematic illustration of a valve element of a valve of an airbag according to the invention according to a further variant;FIG. 14 is a schematic illustration of a valve using valve elements according to FIG. 13 ;FIG. 15 is a schematic sectional view of the valve of FIG. 14 taken along line XV-XV of FIG. 14;FIG. 16 shows a schematic illustration of a valve element of a valve of an airbag according to the invention according to a further variant;FIG. 17 is a schematic illustration of a valve using valve elements according to FIG. 16 ;FIG. 18 is a schematic sectional view of the valve of FIG. 17 along the line XVIII-XVIII of FIG. 17 ;FIG. 19 shows a schematic illustration of the size ratios of the valve elements of a valve of an airbag according to the invention;FIG. 20 shows a schematic illustration of an alternative form of a valve element of a valve of an airbag according to the invention;FIG. 21 shows a schematic illustration of a valve element of a valve of an airbag according to the invention according to a further variant;FIG. 22 is a schematic illustration of the valve using valve elements according to FIG. 21 ;FIG. 23 is a schematic sectional view taken along the line XXIII-XXIII of FIG. 22 ;FIG. 24 is a schematic sectional view taken along the line XXIV-XXIV of FIG. 22 ;FIG. 25 shows a schematic illustration of a valve element of a valve of an airbag according to the invention according to a further variant;FIG. 26 is a schematic illustration of the valve using valve elements according to FIG. 23 ; andFIG. 27 is a schematic sectional view taken along the line XXVII-XXVII of FIG. 26.In the figures, like reference numerals designate identical or substantially identical components and components. For reasons of clarity, not all identical components are always provided with reference numerals.FIG. 1 shows an airbag 10 (only schematically indicated), having an outer wall 12 which has an outflow opening 14 through which gas can outflow outwards from an interior of the airbag 10. A passive valve 16 is arranged on the outflow opening 14, which valve can close or open the outflow opening 14 with a variable gas flow rate.The term "closing" is understood here to mean that the gas flow through the outflow opening 14 through the valve 16 is greatly restricted and at least largely prevented, while the term "release" denotes that gas can flow out through the outflow opening 14 and the valve 16 with a sufficiently low flow resistance in order to allow appreciable gas transport from the airbag 10 into the environment. It is therefore not necessarily the case that, when the valve 16 is closed, no gas at all can flow out of the airbag, nor is it the case that the valve 16 no longer offers any flow resistance at all in its open state.In the first variant shown in FIGS. 1 to 6, the valve 16 comprises exactly two flexible valve elements 18, both of which are arranged on a circumferential edge 20 of the outflow opening 14.Both valve elements 18 are identically shaped and here have the shape of a segment of a circle which, in this variant, extends over a circumferential angle α of 270°.An outer edge 22 of the valve element 18 in the shape of a circular arc encloses a surface section 28 together with an inner edge 24. the inner edge 24 has two sections 24 a, 24 b, which run radially and in a straight line and meet at a bend 26 in the center of the circle. Since the circumferential angle α is greater than 180°, the two inner edge sections 24 a, 24 bdefine a recess 30.The two valve elements 18 are placed on the surface of the outflow opening 14 in such a way that the outer edge 22 runs along the circumferential edge 20 of the outflow opening 14. The valve elements 18 are positioned such that they are arranged mirror-symmetrically with respect to their inner edges 24, i.e. the recess 30 is arranged offset by 180° in both valve elements 18. One of the valve elements 18 is placed over the other valve element 18. Due to the shape of the valve elements 18, both the outer edges 22 and the surface sections 28 overlap in sections, but not the recesses 30.The outer edge 22 of each valve element 18 is held on the circumferential edge 20 of the outflow opening 14 by a fixing 31, in these examples by a seam (illustrated, for example, in FIGS. 5 and 6 ). A connection by other suitable measures, in particular adhesive bonding or welding, would of course also be possible.The valve elements 18 are either fixed along their entire outer edge 22 on the circumferential edge 20 of the outflow opening 14 (see FIGS. 3 to 6 ) or only a portion 32 of the outer edge 22 is fastened on the circumferential edge 20 in each case (see FIGS. 1 and 2 ).In the latter embodiment, the fixed subsection 32 of the outer edge 22 is here the region of the outer edge 22, which is not covered by the respective other valve element 18. This corresponds here to the middle 90° section of the outer edge 22, as can be seen in FIGS. 1 and 2. The overlapping portions 34, 36, also referred to below as first and second circumferential ends, are marked by dotted lines in FIG. 2.In the sections 34, 36 in which they overlap, the valve elements 18 are not fixed either directly to the outer wall 12 of the airbag 10 or to one another in this variant.The sections 34, 36 of one valve element 18 here both rest on the other valve element 18. However, it would also be possible to insert the two valve elements 18 into one another in such a way that one of the sections 34, 36 is in each case on top of and the other section 36, 34 is below the respective other valve element 18.Up to a certain value of the internal pressure in the airbag 10, the mechanical resistance of the valve elements 18 is so high that substantially no gas flows out of the airbag 10 to the outside. If this internal pressure value is exceeded, the forces acting outwards on the valve elements 18 are however high enough to press the valve elements 18 partially outwards, wherein a labyrinth-like flow path is produced from the interior of the airbag 10 between the individual valve elements 18 outwards, through which gas can flow out of the airbag 10. If the internal pressure in the airbag 10 falls again, the valve elements 18 again contact one another and thus close the outflow opening 14 again.The valve 16 is thus designed purely passively and is opened and closed exclusively via the current internal pressure of the airbag 10, wherein the degree of opening is likewise dependent on the internal pressure.In all variants described in this application, it is possible to fix the outer edge 22 circumferentially completely or only in sections on the circumferential edge 20.The mode of operation of the valve 16 is the same for all variants.FIGS. 7 to 12 show a valve 16 in a second variant.The general structure, the functional principle and the arrangement of the valve elements 18 around the outflow opening 14 are analogous to the first variant described above.In contrast to the first variant, a total of four valve elements 18 are present here. These are likewise designed as circle segments, but with a circumferential angle α of 135°.Since the circumferential angle α is less than 180°, the bend 26 forms a point in which the two inner edge sections 24 a, 24 bcomes with one another.The four valve elements 18 are placed one above the other along the circumferential edge 20 of the outflow opening 14 in the manner of flakes or tiles, so that an iris diaphragm arrangement results. Each valve element 18 overlaps at its outer edge 22 with its surface section 28 by a total of approximately two thirds of its length with the two adjacent valve elements 18, wherein in each case a first circumferential end at the section 34 lies on a second circumferential end at the section 36 of the adjacent valve element 18 on the one side and the second circumferential end at the section 36 lies below the first circumferential end at the section 34 of the adjacent valve element 18 on the other side. This is also outlined in the sectional view in FIG. 9.The sections 34, 36 are indicated in FIG. 7 with dashed lines.To produce the valve 16, all the valve elements 18 are placed one above the other in the desired arrangement along the circumferential edge 20 of the outflow opening 14 and then connected to the outer wall 12 of the airbag 10 by means of the fixing 31.In this variant as well, all valve elements 18 are fastened to the circumferential edge 20 of the outflow opening 14 only by a subsection 32, which here too corresponds to the section of the outer edge 22 that is not covered by any of the adjacent valve elements 18, that is to say outside the sections 34, 36.Due to the smaller circumferential angle α, the bend 26, in which the two sections of the inner edge 24 meet, does not form a recess, but a tip, which here is located in each case in the center M of the surface of the outflow opening 14.All valve elements 18 are arranged such that they do not overlap, or overlap only slightly, in the region of the bend 26.In FIGS. 10 to 12, the fixing 31 is designed so as to surround the entire circumferential edge 20 of the outflow opening, so that the valve elements 18 are connected along their entire outer edge 22 to the circumferential edge 20 of the outflow opening 14 and the fixing 31 engages all the valve elements 18 lying one above the other.In the variant shown in FIGS. 13 to 15, four valve elements 18 with a circumferential angle α of 120° are present, while the valve 16 of the variant shown in FIGS. 16 to 18 has four valve elements 18 with a circumferential angle α of 150°. The different circumferential angle α is in each case the only difference compared to the variant shown in FIGS. 10 to 12.The dimensions of the valve elements 18 are selected here such that the valve elements 18 completely cover the surface of the outflow opening 14.In the case of valve elements 18 in the form of segments of a circle, in which the two sections 24 a, 24 bof the inner edge 24 each correspond to the circle radius, these should be longer by a certain amount than the radius of the outflow opening 14, so that the outer edge 22 of the valve elements 18 can be fixed at a sufficient distance concentrically with respect to the center M of the outflow opening 14 along the circumferential edge 20. The inner edge sections 24 a, 24 bshould therefore have a length D which is greater than half the diameter d of the outflow opening 14.It is of course also possible to use differently shaped valve elements 18, for example in a sickle shape as is illustrated in FIG. 20. In this case, the outer edge 22 follows a circular arc, while at least one of the inner edge portions 24 a, 24 bis concave-shaped. Overall, the area of the surface section 28 is thus reduced compared to the other variants shown, which reduces the opening resistance of the valve 16.Just as the exact number of valve elements 18, the specific shape of the valve elements 18 is within the skill of the art.A further variant is shown in FIGS. 21 to 24.Here, four individual valve elements 18 are also present, which are arranged along the circumferential edge 20 of the outflow opening 14 in a similar manner to the variants described above.However, each of the valve elements 18 is here folded into itself, as FIGS. 11 and 13 show, wherein starting from the bend 26 an S-shaped fold 40 is formed, which runs to the outer edge 22 and in which the valve element 18 is folded along radial fold lines 41. The fold 40 is permanently secured therein by a fixation 42, here a seam.Overall, a valve element 18 with a circumferential angle α of 135° is thus again produced (other circumferential angle dimensions can of course also be realized), which however is reinforced by the fold 40 in its surface section 28.The valve elements 18 prefabricated in this way are arranged and fixed here in the same way as those of the previous variant.FIGS. 25 to 27 show yet another variant of a valve 16.Here, the surface section 28 forms a small bulge 44 in the region of the bend 26 at which the two sections 24 a, 24 bof the inner edge 24 meet.When the valve elements 18 are placed one above the other in the desired arrangement along the circumferential edge 20 of the outflow opening 14, all bulges 44 of all valve elements 18 overlap in the region of the center M of the outflow opening 14 (see FIGS. 26 and 27 ).Formed circumferentially around the bulge 44 is a fixing 46, here a seam, which fixes the adjacent valve elements 18 to one another. The fixing 46 is arranged here in the immediate vicinity of the center M of the outflow opening 14, but could also be offset further towards the circumferential edge 20 of the outflow opening.In this variant as well, the outer edge 22 of all valve elements 18 is fixed circumferentially along the circumferential edge 20 of the outflow opening 14.A fabric, in particular an airbag fabric, is used here as material for the valve elements 18. The valve element 18 consists of a single fabric layer or of a plurality of fabric layers lying one above the other. Optionally, the fabric may be provided with a coating. The number of fabric layers used and / or the coating adjusts the stiffness of the valve element 18 and thus influences the flow resistance of the valve 16. These designs are provided by the valves 16 discussed here in accordance with all variants.In all variants described here, all valve elements 18 of a valve 16 are always identically shaped and identically constructed.The invention is described here for a circular outflow opening 14. Accordingly, the valve elements 18 are also designed as circular segments. Of course, the invention can also be applied to other cross-sectional shapes of the outflow opening 14, for example elliptical openings. In this case, the valve elements 18 should likewise generally be shaped as segments of the cross-sectional area which extend over a suitable circumferential angle α.All features of the individual variants can be freely exchanged with one another or combined with one another at the discretion of the person skilled in the art. In particular, the outer edge 22 of the valve elements 18 can be fixed over its entire length or only over a subsection 32 along the circumferential edge 20 of the outflow opening 14. The use of folds 40 in the surface section of the individual valve elements 18 is also conceivable for any desired shapes and circumferential angles α of the valve elements 18. It is likewise possible to use a central bulge 44 for valve elements 18 with an arbitrary circumferential angle α. Optionally, valve elements 18 with and without fold 40 and / or bulge 44 can also be combined in a valve 16. It would also be conceivable to use valve elements 18 with different circumferential angles α in a valve 16.

Claims

Gas bag having an outflow opening (14) in an outer wall (12) which is covered by a valve (16), wherein the valve (16) comprises at least two flexible valve elements (18) which are arranged next to one another along a circumferential edge (20) of the outflow opening (14), wherein each valve element (18) has an outer edge (22) which is arranged on the circumferential edge (20) of the outflow opening (14) and is fixed firmly there at least in sections, and each valve element (18) has a surface section (28) which extends from the circumferential edge (20) into the surface of the outflow opening (14) and ends in an inner edge (24) in the region of the outflow opening (14), wherein the surface sections (28) are unfixed to one another at least in sections in the region of the outflow opening (14) and the surface sections (28) are movable perpendicularly to the surface of the outflow opening (14), such that the outflow opening (14) has a variable gas flow, and wherein the surface sections (28) of adjacent valve elements (18) overlap in sections.The airbag according to claim 1, wherein each valve element (18) is fastened to the peripheral edge (20) only along a partial portion (32) of its outer edge (22).The airbag according to claim 2, wherein each valve element (18) overlaps with exactly two adjacent valve elements (18).The airbag according to any one of claims 2 and 3, wherein a length of the subsection (32) of the outer edge (22) of the valve element (18) fixed to the circumferential edge (20) can be longer than a total length of the subsection(s) of the outer edge (22) not fixed to the circumferential edge (20), in particular twice as long.The airbag according to any one of the preceding claims, wherein 2 to 15, in particular 2, 3 or 4, valve elements (18) are arranged around the circumferential edge (20) of the outflow opening (14).The airbag according to any one of the preceding claims, wherein the outer edge (22) extends over an angle of 30° to 270°, in particular 120°, 135°, 150°, 165° or 270°.The airbag according to any one of the preceding claims, wherein the valve elements (18) have the shape of a segment of a circle and / or together form an iris diaphragm arrangement.The airbag according to any one of the preceding claims, wherein the valve elements (18) are shaped and arranged such that there is a point (M) on the surface of the outflow opening (14) beyond which none of the surface sections (28) radially protrudes.The airbag according to any one of the preceding claims, wherein all valve elements (18) are connected by a circumferential fixing (46) in the surface sections (28).The airbag according to any one of the preceding claims, wherein the surface section (28) of at least one valve element (18) has a fixed fold (40) running into the surface of the outflow opening (14).

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