Bursting membrane unit for a hybrid gas generator, and hybrid gas generator

Abstract

A bursting membrane unit for a hybrid gas generator has a bursting membrane holder (32) with a through-opening (38), which extends in the axial direction (A) and has a central axis (M), and also a bursting membrane, which is connected to the bursting membrane holder (32) via a connecting section (36) on the bursting membrane holder (32) in such a way that the bursting membrane (34) tightly closes the through-opening (38). The connecting section (36) extends all the way around the through-opening (38) in a circumferential direction. Furthermore, an axial central axis (N) of the connecting section (36) is arranged eccentrically with respect to the central axis (M) of the through-opening (38). A hybrid gas generator having such a bursting membrane unit is also provided.

Description

[0001] ZF Airbag Germany GmbH

[0002] Burst membrane unit for a hybrid gas generator and hybrid gas generator

[0003] The invention relates to a rupture membrane unit for a hybrid gas generator, in particular for a protective device in a vehicle, comprising a rupture membrane holder with a through-opening extending in the axial direction and having a central axis, and a rupture membrane which is connected to the rupture membrane holder via a connecting section such that the rupture membrane tightly seals the through-opening. The invention further relates to a hybrid gas generator with such a rupture membrane unit.

[0004] Such burst membrane units and hybrid gas generators are known.

[0005] When a hybrid gas generator is activated, a solid propellant is typically ignited in a combustion chamber, building up operating pressure. When the pressure exceeds a certain threshold, the rupture diaphragm of the rupture diaphragm unit, which isolates the combustion chamber from a propellant-filled chamber, ruptures. Upon opening the rupture diaphragm, a shock wave is generated that travels through the propellant chamber and, at its end, opens a second rupture diaphragm, causing the propellant to flow to a protective device in a vehicle to power components (raising hoods, tightening seatbelts, shifting cushions, etc.) or to inflate gasbags.

[0006] Hybrid gas generators must be designed to reliably supply the gas needed to power or inflate the protective device whenever activated. Furthermore, they must withstand the high pressures that occur during activation. For these reasons, prior art hybrid gas generators are complex to manufacture.

[0007] The object of the invention is to provide a rupture membrane unit for a hybrid gas generator that ensures reliable activation of the hybrid gas generator and simultaneously promotes cost-effective manufacturing of the hybrid gas generator. A further object of the invention is to provide a hybrid gas generator with such a rupture membrane unit.

[0008] The problem is solved by a rupture membrane unit for a hybrid gas generator, in particular for a protective device in a vehicle, comprising a rupture membrane holder with a through-opening extending in the axial direction and having a central axis, and a rupture membrane connected to the rupture membrane holder via a connecting section such that the rupture membrane tightly seals the through-opening. The connecting section extends completely around the through-opening in a circumferential direction. Furthermore, the axial central axis of the connecting section is arranged eccentrically to the central axis of the through-opening, i.e., the axial central axis of the connecting section runs parallel to and spaced apart from the central axis of the through-opening.In accordance with the invention, the central axis of non-circular geometries passes through the center of gravity of the area that spans the corresponding geometry when viewed in the axial direction.

[0009] It was discovered according to the invention that by arranging the connecting section non-concentrically or coaxially with the through-hole, the rupture diaphragm is subjected to a greater one-sided load during activation of the hybrid gas generator than is the case with conventional rupture diaphragm units where the connecting section is arranged coaxially with the through-hole. This results in the rupture diaphragm tearing at lower pressures than in conventional rupture diaphragm units. In this way, without compromising reliability, the hybrid gas generator can be designed for lower pressures and thus manufactured more cost-effectively.

[0010] In particular, the rupture membrane tears at the point on the connecting section where the bending stress is greatest during activation. This point thus forms a predetermined breaking point and is, in particular, the point where the connecting section has the smallest distance to the central axis of the through-hole.

[0011] According to one embodiment, the through-opening has a minimum diametral, i.e., "diametral" to its own central axis, opening width (W) in the radial direction, and the connecting section has a maximum internal distance (V) between two points that are diametral, i.e., "diametral" to its own axial central axis, opposite each other in the radial direction. The axial central axis of the connecting section is radially offset from the central axis of the through-opening by a value that lies within a range between (1Z ~ 1 ' V ' ) x 0.01 and (1Z ~ 1 ' V ' )x 0.99. This design has the advantage that the pressure at which the rupture membrane tears is particularly low.

[0012] Additionally or alternatively, the axial center axis of the connecting section can be radially offset by at least 0.0125 mm relative to the center axis of the through-hole, in particular by at least 0.1 mm, and in particular by at most 0.3 mm. A value within this range ensures that the rupture diaphragm will reliably burst even at low pressures.

[0013] According to another embodiment, the through-opening has a circular cross-section arranged concentrically to its central axis. This design allows for cost-effective manufacturing of the through-opening. Furthermore, this design has the advantage that gas can flow through the through-opening in a defined manner after the rupture membrane has burst.

[0014] Furthermore, it can be provided that the connecting section runs circularly in the circumferential direction and can therefore be manufactured with little effort.

[0015] In one embodiment, the connecting section is arranged in a plane perpendicular to the axial direction, which allows it to be defined with minimal effort.

[0016] In another embodiment, the connecting section is provided on an axial end face of the rupture membrane holder and can therefore be manufactured particularly cost-effectively.

[0017] The rupture membrane holder can have an axially projecting, circumferential bead, the axial, ring-shaped end of which forms the connecting section. This design makes the connecting section particularly effective, and attaching the membrane to the connecting section, e.g., by welding, is geometrically very precise and easy.

[0018] Furthermore, the rupture membrane and the rupture membrane holder can be attached to each other via a material-bonded connection, in particular via a weld. This provides a cost-effective and reliably tight connection between the rupture membrane and the rupture membrane holder.

[0019] According to one embodiment, the rupture membrane holder has a rotationally symmetrical outer surface around an axially extending axis of rotation. The central axis of the through-hole is concentric and / or the axial central axis of the connecting section is eccentric to the axis of rotation. This design allows for cost-effective manufacturing of the rupture membrane holder. Furthermore, a coaxially arranged through-hole offers the advantage that the rupture membrane holder can be positioned within the hybrid gas generator over the outer surface with minimal effort, such that gas flows through the through-hole in a defined manner into a chamber adjacent to the rupture membrane holder, particularly centrally.

[0020] According to the invention, a hybrid gas generator, particularly for a protective device in a vehicle, is also provided to solve the aforementioned problem. This generator comprises a bursting membrane unit according to the invention, offering the aforementioned advantages, and a housing that internally includes a combustion chamber and a propellant gas chamber. In a non-triggered state of the hybrid gas generator, the bursting membrane unit separates the combustion chamber from the propellant gas chamber.

[0021] In this design, the housing between the combustion chamber and the propellant chamber can have a circumferential constriction, to which the rupture membrane unit is attached on the combustion chamber side. This makes the hybrid gas generator particularly cost-effective to manufacture.

[0022] Further advantages will become apparent from the following description and the accompanying drawings. These show: - Figure 1 in a schematic sectional view of a device according to the invention.

[0023] Hybrid gas generator with a burst membrane unit according to the invention, and

[0024] - Figure 2 shows a schematic sectional view of a burst membrane holder of the burst membrane unit from Figure 1.

[0025] The detailed description below, in conjunction with the accompanying drawings, in which identical numbers refer to identical elements, is intended to describe various embodiments of the disclosed subject matter and is not meant to represent the only embodiments. Each embodiment described in this disclosure serves only as an example or illustration and should not be construed as preferable or advantageous over other embodiments.

[0026] All features disclosed below with reference to the exemplary embodiments and / or the accompanying figures can be combined alone or in any subcombination with features of the aspects of the present disclosure, including features of preferred embodiments, provided that the resulting combination of features is meaningful to a person skilled in the art.

[0027] Figure 1 shows a hybrid gas generator 10 for a protective device in a vehicle, which has a housing 12, an ignition unit 14 with an igniter 16, a distribution unit 18 and a primary burst membrane unit 20.

[0028] The housing 12 is formed by a sleeve which extends in axial direction A along a longitudinal axis L and encloses a combustion chamber 22 and a propellant gas chamber 24 inside it.

[0029] A solid propellant is arranged in the combustion chamber 22, while the propellant gas chamber 24 is filled with a propellant gas for driving or inflating the protective device.

[0030] The ignition unit 14 is arranged adjacent to the combustion chamber 22 at a first axial end 26 of the housing 12 and seals it tightly. The igniter 16 is arranged adjacent to or within the combustion chamber 22 in such a way that the igniter 16 ignites the solid propellant when the hybrid gas generator 10 is activated.

[0031] In contrast to the ignition unit 14, the combustion chamber 22 is limited by the primary burst membrane unit 20, which is attached to an axial section 28 of the housing 12, forming a transition between the combustion chamber 22 and the propellant gas chamber 24.

[0032] In the present embodiment, the axial section 28 has a circumferential radial constriction 30, against which the primary burst membrane unit 20 rests via a primary burst membrane holder 32 on the side of the constriction 30 facing the combustion chamber 22.

[0033] In an alternative embodiment, the primary burst membrane unit 20 can be fixed inside the housing 12 in any way, as long as it effectively separates the combustion chamber 22 from the fuel gas chamber 24 when the hybrid gas generator 10 is not activated.

[0034] In this context, the primary burst membrane unit 20 also has a primary burst membrane 34, which is attached to the primary burst membrane holder 32 via a connecting section 36 (see Figure 2) and tightly closes an axial through-opening 38 of the primary burst membrane holder 32.

[0035] The primary burst membrane holder 32 and the primary burst membrane 34 are made of a metal alloy and are connected to each other by means of the connecting section 36.

[0036] The primary rupture membrane 34, for example, is formed from a foil or a thin sheet of metal.

[0037] Additionally or alternatively, the primary rupture membrane 34 can be designed in a disc or lid shape.

[0038] In the present embodiment, the primary burst membrane holder 32 and the primary burst membrane 34 are welded together.

[0039] In principle, the primary burst membrane holder 32 and the primary burst membrane 34 can each be made of any suitable material and / or be tightly connected to each other in any way, in particular by a material bond.

[0040] The through-opening 38 extends in axial direction A from one axial first end face 40 facing the combustion chamber 22 to an opposite axial second end face 42.

[0041] In the present embodiment, the through-opening 38 is designed rotationally symmetric about a central axis M in an axial section between the first end face 40 and an axial end face 44, which runs in the axial direction A.

[0042] Furthermore, the through-opening 38 has an axial section 46 with a smallest diametral opening width W, which here corresponds to the smallest diameter of the through-opening 38.

[0043] In an alternative embodiment, the passage opening 38 can be designed arbitrarily, in particular with one or more cross-sections of arbitrary shape.

[0044] The central axis M is identical to a rotational axis R, around which an outer surface 48 of the primary rupture membrane holder 32 extends rotationally symmetrically between the first end face 40 and the oppositely arranged end face 44.

[0045] In this context, the primary burst membrane holder 32 is attached to the housing 12, in particular to the constriction 30, via the outer surface 48, for example by means of a material bond.

[0046] The primary rupture diaphragm holder 32 can be arranged centrally in the housing 12, so that the central axis M coincides with the longitudinal axis L.

[0047] On the axial second end face 42 facing the propellant gas chamber 24, the primary burst diaphragm holder 32 in the present embodiment has a bead 50 projecting axially A from the end face 44 and circumferentially around an axial central axis N, the free axial end 52 of which forms the connecting section 36. The axial end 52 is rotationally symmetrical to the axial central axis N and is thus circular and arranged in a plane perpendicular to the axial central axis N.

[0048] In this context, the connecting section 36 has a smallest diametrical inner distance V, which here corresponds to the diameter or inner diameter of the connecting section 36.

[0049] In the present embodiment, the bead 50 forms a welding lip.

[0050] In principle, the connecting section 36 can be designed in any way.

[0051] In an alternative embodiment, the connecting section 36 can have an arbitrarily shaped cross-section perpendicular to the central axis M, for example, oval. In the case of non-circular geometries, the axial central axis N passes through the centroid of the area that the corresponding geometry spans when viewed in the axial direction A.

[0052] In all embodiments, the axial central axis N extends in axial direction A and is radially spaced from the central axis M by a distance D. In other words, the axial central axis N is eccentric to the central axis M.

[0053] The distance D here is 0.15 mm.

[0054] In an alternative embodiment, the distance D can be in a range between 1 - - x 0.01 and 1 - - x 0.99 hegen.

[0055] 2 2 a

[0056] Furthermore, the distance D can be at least 0.0125 mm, in particular at least 0.1 mm.

[0057] Additionally or alternatively, the distance D can be a maximum of 0.3 mm.

[0058] Adjacent to the first end face 40, a perforated protective plate 54 (see Figure 1) is arranged in the combustion chamber 22, which is located between the solid propellant and the primary burst membrane unit 20.

[0059] Furthermore, the distributor unit 18 is arranged at the second axial end 56 of the housing 12, which is positioned opposite the first axial end 26. The distributor unit 18 has a perforated distributor cap 58, which encompasses the second axial end 56 on the outside and defines a distributor chamber 60 on the inside.

[0060] The distributor chamber 60 is connected to the propellant gas chamber 24 via an outlet opening 62, which is formed here by the opening at the second axial end 56 of the sleeve-shaped housing 12.

[0061] Furthermore, the distributor unit 18 has a secondary burst membrane unit 64 arranged in the outlet opening 62, which here is designed analogously to the primary burst membrane unit 20 with a secondary burst membrane holder 66 and a secondary burst membrane 68.

[0062] In principle, the secondary burst membrane unit 64 can be designed arbitrarily, in particular with an arbitrarily designed secondary burst membrane holder 66 and an arbitrarily designed secondary burst membrane 68.

[0063] In a non-triggered state of the hybrid gas generator 10, the primary burst membrane unit 20 separates the combustion chamber 22 from the propellant gas chamber 24, thereby isolating the combustion chamber 22 from the propellant gas chamber 24.

[0064] Furthermore, in the non-triggered state of the hybrid gas generator 10, the secondary burst membrane unit 64 separates the propellant gas chamber 24 from the distribution chamber 60, thereby isolating the propellant gas chamber 24 from the distribution chamber 60.

[0065] When the hybrid gas generator 10 is activated, the igniter 16 ignites the solid propellant in the combustion chamber 22. This creates a functional pressure in the combustion chamber 22, which acts on the primary burst membrane 34 via the through-opening 38 and bulges it outwards towards the propellant gas chamber 24.

[0066] As soon as the pressure exceeds a certain threshold, for example 1000 bar, the primary rupture diaphragm 34 is ruptured. Due to the eccentric arrangement of the connecting section 36 relative to the through-hole 38, the primary rupture diaphragm 34 first tears at the point on the connecting section 36 that is closest to the central axis M of the through-hole 38, as this is where the point of highest material stress is located. This point essentially forms a predetermined breaking point. The effect is thus due to a controlled weakening of the primary rupture diaphragm 34. As a result, the primary rupture diaphragm 34 does not tear abruptly, but rather peels open from the predetermined breaking point to the opposite side of the connecting section 36.

[0067] When the primary burst membrane 34 is cut, a shock wave is formed which passes through the propellant gas chamber 24 and cuts through the secondary burst membrane 68, causing the propellant gas to flow from the propellant gas chamber 24 under high pressure into the distributor chamber 60 and finally via the perforated distributor cap 58 to the vehicle's protective device.

[0068] In this context, a basket 70 is arranged in the propellant gas chamber 24 adjacent to the side of the secondary burst membrane unit 64 facing the propellant gas chamber 24, which is designed to retain parts of the primary burst membrane 34 that may detach from the primary burst membrane holder 32 when the hybrid gas generator 10 is activated.

[0069] In this way, a burst membrane unit 20 for a hybrid gas generator 10 and a hybrid gas generator 10 with such a burst membrane unit 20 is provided, which can ensure reliable activation of the hybrid gas generator 10 at low pressures, in particular by the fact that the axial central axis N of the connecting section 36 is arranged eccentrically to the central axis M of the through-hole 38.

[0070] This means that the hybrid gas generator 10 only needs to be designed for these low pressures and can therefore be manufactured particularly cost-effectively.

[0071] Furthermore, in certain embodiments, the primary burst membrane 34 remains completely connected to the primary burst membrane holder 32 even after activation, so that the basket 70 can be omitted in these embodiments.

Claims

1. Patent claims 1. Burst membrane unit (20) for a hybrid gas generator (10), in particular for a protective device in a vehicle, comprising a burst membrane holder (32) with a through-opening (38) extending in the axial direction (A) and having a central axis (M), and a burst membrane (34) which is connected to the burst membrane holder (32) via a connecting section (36) such that the burst membrane (34) tightly closes the through-opening (38), wherein the connecting section (36) extends completely around the through-opening (38) in a circumferential direction, characterized in that an axial central axis (N) of the connecting section (36) is arranged eccentrically to the central axis (M) of the through-opening (38).

2. Burst membrane unit (20) according to claim 1, characterized in that the through-opening (38) has a smallest diametral opening width (W) in the radial direction and the connecting section (36) has a maximum inner distance (V) between two diametrically opposed points in the radial direction, wherein the axial central axis (N) of the The connecting section (36) is radially offset from the central axis (M) of the through-opening (38) by a value which is in a range between 0.01 and 1 - - x 0.99 hegt. 2 a 3. Burst membrane unit (20) according to claim 1 or 2, characterized in that the axial central axis (N) of the connecting section (36) is radially offset by at least 0.0125 mm relative to the central axis (M) of the through-opening (38), in particular by at least 0.1 mm, and in particular by at most 0.3 mm.

4. Burst membrane unit (20) according to one of the preceding claims, characterized in that the through-hole (38) has a circular cross-section which is arranged concentrically to the central axis (M) of the through-hole (38).

5. Burst membrane unit (20) according to one of the preceding claims, characterized in that the connecting section (36) extends circularly in the circumferential direction.

6. Burst membrane unit (20) according to one of the preceding claims, characterized in that the connecting section (36) is arranged in a plane perpendicular to the axial direction (A).

7. Burst membrane unit (20) according to one of the preceding claims, characterized in that the connecting section (36) is provided on an axial end face (42) of the burst membrane holder (32).

8. Burst membrane unit (20) according to claim 7, characterized in that the burst membrane holder (32) has an axially projecting, circumferential bead (50) whose axial, annular circumferential end (52) forms the connecting section (36).

9. Burst membrane unit (20) according to one of the preceding claims, characterized in that the burst membrane (34) and the burst membrane holder (32) are attached to each other via a material-bonded connection, in particular via a weld seam.

10. Burst membrane unit (20) according to one of the preceding claims, characterized in that the burst membrane holder (32) has a rotationally symmetric outer surface (48) about an axis of rotation (R) extending in the axial direction (A), wherein the central axis (M) of the through-hole (38) is arranged concentrically and / or the axial central axis (N) of the connecting section (36) is arranged eccentrically to the axis of rotation (R).

11. Hybrid gas generator (10), in particular for a protective device in a vehicle, comprising a burst membrane unit (20) according to one of the preceding claims and a housing (12) which internally comprises a combustion chamber (22) and a propellant gas chamber (24), wherein in a non-triggered state of the hybrid gas generator (10) the burst membrane unit (20) separates the combustion chamber (22) from the propellant gas chamber (24).

12. Hybrid gas generator (10) according to claim 11, characterized in that the housing (12) has a circumferential constriction (30) between the combustion chamber (22) and the propellant gas chamber (24), on which the burst membrane unit (20) is attached on the side of the combustion chamber (22).

Images