Gas generator

Abstract

A gas generator (10), in particular for a protective device in a vehicle, has: an outer housing (12) which has a combustion chamber (70); an ignition tube (46) which is surrounded by the combustion chamber (70), delimits an ignition space (66) on the inside and is fastened to the outer housing (12) via a base (50); and an igniter (48) which is fastened to the base (50) and axially adjoins the ignition space (66). The ignition tube (46) has at least one slot (76) which is elongate in the axial direction (A) and via which the ignition space (66) is connected to the combustion chamber (70).

Description

[0001] Gas generator

[0002] The invention relates to a gas generator, in particular for a protective device in a vehicle, with an outer housing which has a pot-shaped diffuser with a base section and a closure body, wherein the diffuser and the closure body lie opposite one another in the axial direction and a combustion chamber is present in the interior of the outer housing, an ignition tube surrounded by the combustion chamber, which on the inside delimits an ignition chamber filled with a pyrotechnic booster charge and is fastened to the outer housing via a base, and an igniter fastened to the base and axially adjacent to the ignition chamber.

[0003] Gas generators for protective devices in a vehicle drive parts (e.g., raising the hood, tightening the seat belt, moving upholstery, etc.) or inflate gas bags.

[0004] In order to meet high safety standards, gas generators must be functional for single use over many years, which means that during this time they are subject to high demands in terms of resistance to environmental influences such as moisture ingress or corrosion.

[0005] Furthermore, gas generators must be designed to reliably provide the gas to drive or inflate the protective device at all times when activated.

[0006] The object of the invention is to provide a gas generator which provides gas particularly reliably after activation.

[0007] The object is achieved by a gas generator according to the preamble of claim 1, in which the ignition tube has at least one slot which is elongated in the axial direction and via which the ignition chamber is connected to the combustion chamber. For the purposes of the invention, an axially elongated slot is a slot which has the greatest extension in the axial direction. In the following, the axially elongated slot is referred to as the axial slot. It was recognized according to the invention that an axial slot is and remains open much more reliably than a circular through-hole. Furthermore, due to its elongated extension in the axial direction, the axial slot promotes the ignition gas formed in the ignition chamber when the booster charge is activated, flowing via the at least one axial slot to the fuel arranged in the combustion chamber and effectively igniting it.

[0008] The axial slot can be provided at the end of the ignition chamber facing the base and extend over at least 10% of the axial height of the ignition chamber, in particular with the slot beginning at the end of the ignition tube closest to the base. As a result, the ignition gas flows reliably into the axially lower region of the combustion chamber, i.e., the region remote from the base section of the diffuser, where it ignites the fuel located in the lower region. In this way, after activation of the gas generator, gas is provided particularly reliably to drive or inflate the protective device, which gas is formed during the combustion of the fuel.

[0009] Additionally or alternatively, the ignition tube can have at least two or at least three axial slots, in particular arranged at equal distances from one another in the circumferential direction. This design has the advantage that the ignition gas flows through several slots simultaneously into the combustion chamber to the fuel and ignites it at several points.

[0010] According to one embodiment, in particular according to the preamble of claim 1, the ignition tube has an open first axial end facing the base and an opposite open second axial end, which is axially opposite the base section of the diffuser. By designing the ignition tube as a tube open on both sides, it can be manufactured with particularly low effort, even if it is made of high-strength steel. In particular, deep drawing is not required as a manufacturing step.

[0011] In a non-activated state of the gas generator, the second axial end can be closed by clamping the ignition tube between the diffuser and the base. When the gas generator is activated, a bottom section of the diffuser bulges out to expose the second axial end. In this way, the ignition chamber is effectively closed before and during ignition of the booster charge, while the ignition chamber remains open after ignition of the booster charge and the fuel.

[0012] According to one embodiment, the base section of the diffuser, when the gas generator is not activated, directly adjoins the second axial end of the ignition tube, sealing it tightly. Thus, the second axial end of the ignition tube is directly sealed by the outer housing, making the gas generator particularly efficient.

[0013] According to an alternative embodiment, the gas generator has a seal that, in the non-activated state of the gas generator, is arranged axially between the second axial end of the ignition tube and the base portion of the diffuser, so that the second axial end of the ignition tube is tightly sealed. In this way, the second axial end of the ignition tube is sealed via the seal and thus indirectly by the outer housing.

[0014] Furthermore, it can be provided that the closure body is pot-shaped and has a base section and a peripheral wall section that extends in the axial direction away from the base section of the closure body and toward the base section of the diffuser, thus radially delimiting the combustion chamber. In the non-activated state of the gas generator, the base section of the diffuser rests against a first end of the peripheral wall section of the closure body. In particular, the peripheral wall section of the closure body can have a smaller diameter at the first end than at a second end adjacent to the base section of the closure body. As a result, the outer housing and the combustion chamber are designed to be particularly effective and efficient.

[0015] The gas generator can be designed such that, after activation of the igniter, the booster charge burns in the ignition chamber of the ignition tube, wherein particles and ignition gas formed during combustion flow via the at least one axial slot into the combustion chamber, in particular in a direction that is at least partially axially directed toward the base portion of the closure body, and ignites a fuel arranged in the combustion chamber. During combustion of the fuel, an inflation gas is formed which axially expands the outer casing such that an outlet gap running circumferentially is formed between the base portion of the diffuser and the first end of the circumferential wall portion of the closure body, and the escaping gas flows into a diffuser chamber running circumferentially and formed radially between the circumferential wall portion of the closure body and a circumferential wall portion of the diffuser.The inflation gas flows radially out of the gas generator via outlet holes in the peripheral wall section of the diffuser. This provides the gas generator with a particularly favorable gas flow upon activation, reliably ensuring effective gas generation.

[0016] In one embodiment, the igniter is embedded in the base by casting or overmolding and is thus securely and cost-effectively attached.

[0017] In this case, the ignition tube can be sealed to the base during casting or overmolding, whereby the ignition chamber is effectively closed when the gas generator is not activated and is essentially only connected to the combustion chamber via at least one axial slot.

[0018] In a further embodiment, the base extends through a central opening in the closure body, whereby the outer housing has a particularly high strength.

[0019] The base can form a receiving geometry for an igniter plug, so that the gas generator is designed to be particularly efficient.

[0020] Furthermore, the closure body can be provided with a central recess, as seen from the outside, into which the base protrudes from the inside of the gas generator. Preferably, the recess is completely lined on the outside by the base. This makes the gas generator particularly compact and highly resistant to environmental influences such as moisture ingress.

[0021] The recess can be pot-shaped and have a bottom with a depression and / or bulge that is completely filled or surrounded by the base. This has the advantage that the recess is reliably sealed by the base. Furthermore, the base is effectively secured to the ground.

[0022] Further advantages and features are evident from the following description and the attached drawings. These show:

[0023] - Figure 1 shows a schematic sectional view of an inventive

[0024] Gas generator in non-activated state,

[0025] - Figure 2 shows a schematic sectional view of the gas generator from

[0026] Figure 1 in the activated state,

[0027] - Figure 3 shows in a perspective view an ignition tube of the

[0028] Gas generator from Figure 1 , and

[0029] - Figure 4 shows a schematic sectional view of an inventive

[0030] Gas generator according to another embodiment in the non-activated state.

[0031] The following detailed description, taken in conjunction with the accompanying drawings, in which like numerals refer to like elements, is intended to describe various embodiments of the disclosed subject matter and is not intended to be the only embodiments. Each embodiment described in this disclosure is merely exemplary or illustrative and should not be construed as preferred or advantageous over other embodiments.

[0032] All features disclosed below with respect to the embodiments and / or the accompanying figures may be combined alone or in any sub-combination 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.

[0033] Figure 1 shows a gas generator 10 with an outer housing 12 composed of a cup-shaped diffuser 14 and a cup-shaped closure body 16. The gas generator 10 is particularly designed to drive or activate a protective device in a vehicle.

[0034] The diffuser 14 has a bottom portion 18 and a substantially cylindrical peripheral wall portion 20 extending in the axial direction A.

[0035] In the peripheral wall section 20 of the diffuser 14, a plurality of, for example twelve, outflow holes 22 are formed, which are evenly distributed over the circumference of the diffuser 14 and arranged at an axial height.

[0036] The closure body 16 has a bottom portion 24 and a peripheral wall portion 26 which extends counter to the axial direction A away from the bottom portion 24 and towards a first end 28 of the peripheral wall portion 26 and is arranged radially inwardly of the peripheral wall portion 20 of the diffuser 14.

[0037] The peripheral wall section 26 of the closure body 16 has a first diameter d at its first end 28 and a second diameter D at an axially opposite second end 30, which adjoins the base section 24.

[0038] In the present embodiment, the first diameter d is smaller than the second diameter D, whereby the closure body 16 is radially bulged near the bottom portion 24 of the closure body 16 and tapers counter to the axial direction A towards the bottom portion 18 of the diffuser 14.

[0039] The peripheral wall section 26 of the closure body 16 rests at its second end 30 radially on the inside against the peripheral wall section 20 of the diffuser 14 and is firmly connected thereto by means of a circumferential weld seam 32.

[0040] Furthermore, in a non-activated state of the gas generator 10, which is illustrated in Figure 1, the peripheral wall section 26 of the closure body 16 extends to the base section 18 of the diffuser 14, so that the first end 28 of the peripheral wall section 26 bears against the base section 18 of the diffuser 14 at the end face, in particular in a ring-shaped manner in the circumferential direction. As a result, a diffuser chamber 34 is formed in the radial direction between the peripheral wall section 26 of the closure body 16 and the peripheral wall section 20 of the diffuser 14, which diffuser chamber 34 extends in the circumferential direction and borders the outflow holes 22 radially on the outside.

[0041] The cup-shaped diffuser 14 and the cup-shaped closure body 16 are thus arranged in opposite directions, nested within one another, so that the inner sides of the base sections 18, 24 are opposite one another, and delimit the interior 36 of the outer housing 12.

[0042] In this context, the closure body 16 has a central recess 38 with a central opening 40.

[0043] The indentation 38 extends into the interior 36 of the outer housing 12 or opposite to the axial direction A to the bottom section 18 of the diffuser 14.

[0044] Furthermore, the indentation 38 is pot-shaped with a bottom 42 which has an annular bulge 44.

[0045] In addition or alternatively to the annular bulge 44, the bottom 42 of the cup-shaped indentation 38 can have an annular depression in a further embodiment.

[0046] Furthermore, an ignition tube 46 and an igniter 48 are arranged in the interior 36 of the outer housing 12, which are fastened to the closure body 16 via a base 50.

[0047] The base 50 has an inner section 52 arranged in the interior 36 and an outer section 54 arranged in the recess 38, which are connected to one another by the central opening 40.

[0048] The outer section 54 completely lines the recess 38 and forms therein a receiving geometry 56 for an igniter plug (not shown), into which contact pins 58 of the igniter 48 extend.

[0049] The igniter 48 is embedded in the inner section 52, for example by overmolding or overmolding, and is thus positively connected to the base 50. Furthermore, the inner section 52 completely fills the recess 44, thereby providing a particularly stable connection between the base 50 and the closure body 16.

[0050] In this context, the ignition tube 46 has an open first axial end 60 facing the bottom portion 24 of the closure body 16 and an axially opposite open second axial end 62 facing the bottom portion 18 of the diffuser 14.

[0051] The ignition tube 46 is cylindrical, in particular circular-cylindrical.

[0052] At the first axial end 60, the ignition tube 46 is tightly connected to the inner section 52.

[0053] For example, when the igniter 48 is cast or overmolded with the base 50, the inner section 52 can be cast or overmolded onto the ignition tube 46.

[0054] In an alternative embodiment, the ignition tube 46 is plugged onto the inner section 52 in the axial direction A during assembly.

[0055] For this purpose, the ignition tube 46 can have a chamfer 64 (see Figure 3) on the radial inside at the first axial end 60 in order to facilitate insertion.

[0056] The ignition tube 46 defines an ignition chamber 66 on the inside, to which the igniter 48 is axially adjacent.

[0057] In the non-activated state of the gas generator 10, the ignition tube 46 is clamped in the axial direction A between the diffuser 14 and the base 50. In the illustrated embodiment, the bottom section 18 of the diffuser 14 rests directly against the ignition tube 46 at the end face and closes the second axial end 62, preferably tightly.

[0058] In an alternative embodiment (see Figure 4), the gas generator 10 has a seal 68 arranged in the axial direction A between the second axial end 62 and the base portion 18 of the diffuser 14 to tightly seal the second axial end 62 in the non-activated state of the gas generator 10. Preferably, the seal 68 is attached to the base portion 18 of the diffuser 14 opposite the second axial end 62 of the ignition tube 46.

[0059] The seal 68 is, for example, a disc-shaped component such as a silicone disc.

[0060] The embodiment of the gas generator 10 shown in Figure 4 is, apart from the seal 68, identical to the embodiment of the gas generator 10 shown in Figure 1.

[0061] In all embodiments, the ignition tube 46 is surrounded radially outwardly by a combustion chamber 70, which is also delimited by the closure body 16, both radially and axially, and the bottom section 18 of the diffuser 14.

[0062] The combustion chamber 70 is at least partially filled with a fuel 72, which is schematically represented in Figure 1 by a plurality of tablets and which, upon combustion, produces an inflation gas, ie a gas intended to drive or inflate the protective device.

[0063] The ignition chamber 66 is at least partially filled with a pyrotechnic booster charge 74, which is schematically represented in Figure 1 by several tablets and which is designed to ignite the fuel 72 in the combustion chamber 70 after its ignition by the igniter 48.

[0064] For this purpose, the ignition tube 46 has at least one axial slot 76 which connects the ignition chamber 66 to the combustion chamber 70 and through which the particles and ignition gases formed during the combustion of the booster charge 74 flow into the combustion chamber 70 upon activation of the gas generator 10.

[0065] In the present embodiment, the ignition tube 46 has three axial slots 76 (see Figure 3) which are arranged at equal distances from one another in the circumferential direction, ie the three axial slots 76 are each arranged offset from one another at an angle of 120°.

[0066] The axial slots 76 each have a width B in the circumferential direction and an axial length L that is greater than the width B, in particular at least twice as large. In the embodiment shown in Figure 3, the axial length L is approximately 50% of the total axial length G of the ignition tube 46.

[0067] In principle, the axial length L can be any proportion of the total axial length G, preferably at least 25%.

[0068] Furthermore, the axial slots 76 extend in the axial direction A to the first axial end 60 or to the end 78, which is near or adjacent to the base 50. Thus, the axial slots 76 are arranged in the axial half of the ignition tube 46 facing the base 50.

[0069] In principle, the axial slots 76 can be arranged at any axial height in the ignition tube 46.

[0070] Preferably, the axial slots 76 are arranged adjacent to the axial end 80 of the ignition chamber 66, which is adjacent to the base 50.

[0071] Additionally or alternatively, in a preferred embodiment, the axial slots 76 extend over at least 10% of the axial height H of the ignition chamber 66 (see Figure 1).

[0072] In order to provide the inflation gas for driving or inflating the protective device, the igniter 48 is first activated, thereby igniting the booster charge 74.

[0073] During the combustion of the booster charge 74, particles and ignition gas are formed in the ignition chamber 66 closed by the bottom section 18 of the diffuser 14.

[0074] This increases the pressure in the ignition chamber 66, causing the particles and the ignition gas to flow through the axial slots 76 into the combustion chamber 70, where they ignite the fuel 72. The flow pattern is illustrated by arrows in Figure 2.

[0075] The particles and the ignition gas flow through the axial slots 76 in a direction that points at least partially in the axial direction A toward the bottom portion 24 of the closure body 16, so that fuel 72 located near the bottom portion 24 of the closure body 16 is also reliably ignited. During the combustion of the fuel 72, inflation gas is formed in the combustion chamber 70, causing the pressure in the combustion chamber 70 to rise so sharply that the bottom portion 18 of the diffuser 14 bulges outward or expands away from the closure body 16 in the opposite direction to the axial direction A.

[0076] This state, which is shown in Figure 2 and in which the gas generator 10 or the outer housing 12 is axially expanded, is referred to as the activated state of the gas generator 10.

[0077] In the activated state of the gas generator 10, the ignition tube 46 is no longer clamped between the diffuser 14 and the base 50, but rather the second axial end 62 is released, thus leaving the ignition chamber 66 axially open at this point. This can apply analogously to the embodiment shown in Figure 4 with seal 68.

[0078] Furthermore, in the activated state of the gas generator 10, the outer housing 12 is widened to such an extent that an outlet gap 82 (see Figure 2) extending circumferentially is formed between the bottom section 18 of the diffuser 14 and the first end 28 of the peripheral wall section 26 of the closure body 16, through which the inflation gas flows from the combustion chamber 70 in the radial direction into the diffuser chamber 34.

[0079] Finally, the inflation gas flows out of the diffuser chamber 34 via the outflow holes 22 in a radial direction out of the gas generator 10 and towards the corresponding protective device.

[0080] In this way, a gas generator 10 is formed which, after activation, provides gas particularly reliably and can be produced cost-effectively.

Claims

Patent claims 1. Gas generator (10), in particular for a protective device in a vehicle, with an outer housing (12) having a pot-shaped diffuser (14) with a base section (18) and a closure body (16), wherein the diffuser (14) and the closure body (16) are opposite one another in the axial direction (A) and a combustion chamber (70) is present in the interior (36) of the outer housing (12), an ignition tube (46) surrounded by the combustion chamber (70), which defines on the inside an ignition chamber (66) filled with a pyrotechnic booster charge (74) and is fastened to the outer housing (12) via a base (50), and an igniter (48) fastened to the base (50) and axially adjoins the ignition chamber (66), characterized in that the ignition tube (46) has at least one slot (76) elongated in the axial direction (A), via which the ignition chamber (66) connected to the combustion chamber (70).

2. Gas generator (10) according to claim 1, characterized in that the axial slot (76) is provided at the end (80) of the ignition chamber (66) facing the base (50) and extends over at least 10% of the axial height (H) of the ignition chamber (66), in particular wherein the slot (76) begins from the end (78) of the ignition tube (46) near the base (50).

3. Gas generator (10) according to claim 1 or 2, characterized in that the ignition tube (46) has at least two or at least three axial slots (76), in particular which are arranged at equal distances from one another in the circumferential direction.

4. Gas generator (10) according to one of the preceding claims, in particular according to the preamble of claim 1, characterized in that the ignition tube (46) has an open first axial end (60) facing the base (50) and an opposite open second axial end (62), which is opposite the bottom section (18) of the diffuser (14) in the axial direction (A).

5. Gas generator (10) according to claim 4, characterized in that in a non-activated state of the gas generator (10) the second axial end (62) is closed by the ignition tube (46) being clamped between the diffuser (14) and the base (50), and in an activated state of the gas generator (10) a bottom section (18) of the diffuser (14) bulges out such that the second axial end (62) is exposed.

6. Gas generator (10) according to claim 4 or 5, characterized in that the bottom section (18) of the diffuser (14) in the non-activated state of the gas generator (10) lies directly against the second axial end (62) of the ignition tube (46) and in particular tightly closes it.

7. Gas generator (10) according to claim 4 or 5, characterized in that the gas generator (10) has a seal (68) which, in the non-activated state of the gas generator (10), is arranged in the axial direction (A) between the second axial end (62) of the ignition tube (46) and the bottom section (18) of the diffuser (14), so that the second axial end (62) of the ignition tube (46) is tightly closed.

8. Gas generator (10) according to one of the preceding claims, characterized in that the closure body (16) is pot-shaped and has a base section (24) and a peripheral wall section (26) which extends in the axial direction (A) away from the base section (24) of the closure body (16) and towards the base section (18) of the diffuser (14) and delimits the combustion chamber (70) radially outwards, wherein the base section (18) of the diffuser (14) rests on the end face of a first end (28) of the peripheral wall section (26) of the closure body (16) in the non-activated state of the gas generator (10), in particular wherein the peripheral wall section (26) of the closure body (16) has a smaller diameter (d) at the first end (28) than at a second end (30) which adjoins the base section (24) of the closure body (16).

9. Gas generator (10) according to claim 8, characterized in that the gas generator (10) is designed such that after activation of the igniter (48) the booster charge (74) burns in the ignition chamber (66) of the ignition tube (46), wherein particles and ignition gas formed during combustion flow via the at least one axial slot (76) into the combustion chamber (70), in particular in a direction that points at least partially in the axial direction (A) towards the base section (24) of the closure body (16), and ignites a fuel (72) arranged in the combustion chamber (70), wherein during the combustion of the fuel (72) an inflation gas is formed that axially expands the outer casing (12) such that a circumferentially extending outlet gap (82) is formed between the base section (18) of the diffuser (14) and the first end (28) of the circumferential wall section (26) of the closure body (16), and the escaping gas flows into a circumferentially extending diffuser chamber (34),which is formed in the radial direction between the peripheral wall section (26) of the closure body (16) and a peripheral wall section (20) of the diffuser (14), wherein the inflation gas flows out of the gas generator (10) in the radial direction via outflow holes in the peripheral wall section (20) of the diffuser (14).

10. Gas generator (10) according to one of the preceding claims, characterized in that the igniter (48) is embedded in the base (50) by casting or overmolding.

11. Gas generator (10) according to claim 10, characterized in that the ignition tube (46) is sealed to the base (50) during casting or injection molding.

12. Gas generator (10) according to one of the preceding claims, characterized in that the base (50) extends through a central opening (40) in the closure body (16).

13. Gas generator (10) according to claim 12, characterized in that the base (50) forms a receiving geometry (56) for an igniter plug.

14. Gas generator (10) according to one of the preceding claims, characterized in that the closure body (16), seen from the outside, has a central indentation (38) into which the base (50) projects from the interior (36) of the gas generator (10), preferably wherein the indentation (38) is completely lined towards the outside by the base (50).

15. Gas generator (10) according to claim 14, characterized in that the indentation (38) is pot-shaped and has a bottom (42) with a depression and / or bulge (44) which is filled or surrounded by the base (50).

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