GAS GENERATOR AND PROTECTIVE DEVICE WITH GAS GENERATOR

Abstract

A gas generator (20) has an outer housing (22) with a combustion chamber (76), an ignition cap (44) surrounded by the combustion chamber (76), which internally defines an ignition chamber (72) filled with a pyrotechnic booster charge (84) and is attached to the outer housing (22) via a base (48), and an electric igniter (46) attached to the base (48) and axially adjacent to the ignition chamber (72). The ignition cap (44) has a cylindrical circumferential wall (60) and a top wall (58) that closes an axial end (56) of the circumferential wall (60) and is integrally connected to the circumferential wall (60). The top wall (58) is curved in the axial direction (A) into the interior space (62) enclosed by the circumferential wall (60). The invention further relates to a protective device with such a gas generator (20).

Description

[0001] The invention relates to a gas generator, particularly for a protective device in a vehicle, comprising an outer housing containing a combustion chamber, an ignition cap surrounded by the combustion chamber which internally defines an ignition chamber filled with a pyrotechnic booster charge and is attached to the outer housing via a base, and an electric igniter attached to the base and enclosed by an igniter outer wall, which is axially adjacent to the ignition chamber. The invention further relates to a protective device in a vehicle, comprising a gasbag and such a gas generator for inflating the gasbag.

[0002] Gas generators for protective devices in a vehicle power, for example, parts (raising engine hoods, tightening the seat belt, moving cushions or the like) or inflate gas bags.

[0003] To meet high safety standards, gas generators must remain functional for single use for many years, meaning they are subject to high demands during this time regarding resistance to environmental influences such as moisture ingress or corrosion.

[0004] Furthermore, gas generators must be designed to reliably provide the gas for powering or inflating the protective device at all times when they are activated.

[0005] The object of the invention is to provide a gas generator that reliably supplies gas after activation. A further object of the invention is to provide a protective device incorporating such a gas generator.

[0006] The problem is solved by a gas generator, particularly for a protective device in a vehicle, comprising an outer housing containing a combustion chamber, an ignition cap surrounded by the combustion chamber, which internally defines an ignition chamber filled with a pyrotechnic booster charge and is attached to the outer housing via a base, and an electric igniter attached to the base and enclosed by an igniter outer wall, which is axially adjacent to the ignition chamber. The ignition cap has an axially extending cylindrical circumferential wall and a radially extending top wall, which completely closes one axial end of the circumferential wall and is integrally connected to it. The top wall is convex in the axial direction into the interior enclosed by the circumferential wall.

[0007] It was discovered according to the invention that the ignition chamber of the ignition cap can be reduced in a defined manner by curving the ceiling wall into the interior. In this way, it is reliably ensured that in all positions or orientations of the gas generator, in particular a lateral or overhead position, the pyrotechnic booster charge is arranged so close to the igniter or held by the ceiling wall that the igniter ignites the booster charge directly and effectively when the gas generator is activated.

[0008] According to one embodiment, the ceiling wall is inverted to such an extent that the inverted section has a cylindrical inner wall running parallel to the circumferential wall and a central section extending inwards from it. In other words, the axial end, which is closed off by the ceiling wall, is turned inwards, thus forming a double wall and being particularly stable.

[0009] The inner wall can have an axial length that corresponds to at least 50% of the axial length of the ceiling wall, in particular at least 75%, whereby the inverted section itself is pot-shaped.

[0010] Additionally or alternatively, viewed axially, the central section can enclose at least 50% of the axial cross-sectional area of ​​the interior and / or the central section can be flat, i.e., extending radially at a constant axial height, or concave. This design has the advantage that the central section forms a defined contact surface for the pyrotechnic booster charge over a large portion of the axial cross-sectional area at a given axial height.

[0011] Furthermore, it can be provided that the inner wall rests radially against the circumferential wall on its inner side or is spaced from the circumferential wall by an annular gap that is free of pyrotechnic booster charge. This ensures that no part of the pyrotechnic booster charge can slip or fall into the annular gap, and thus essentially the entire pyrotechnic booster charge remains or is arranged axially between the central section and the igniter.

[0012] According to a further embodiment, the ignition chamber is filled with the pyrotechnic booster charge at least to such an extent that the pyrotechnic booster charge is adjacent to the igniter in every position or orientation of the gas generator. This ensures that the igniter ignites the pyrotechnic booster charge in a particularly short time when the gas generator is activated.

[0013] The perimeter wall can have at least one outlet opening through which the ignition chamber is connected to the combustion chamber. Upon activation, the ignition gas formed in the ignition chamber flows through the outlet opening to the fuel located in the combustion chamber and ignites it.

[0014] In one embodiment, the ceiling wall is closed and therefore free of outflow openings, which makes the ignition cap inexpensive to manufacture.

[0015] Furthermore, it can be ensured that the volume of the ignition chamber remains constant before, during, and after activation of the gas generator, apart from any potential thermal expansion of the ignition cap. Thus, the activation of the gas generator always proceeds in the same and therefore controlled manner.

[0016] In another embodiment, the gas generator is a single-stage gas generator and is therefore particularly simple and cost-effective.

[0017] The ignition cap can also be attached to the base in such a way that it remains attached even after the gas generator has been activated. This ensures a particularly controlled activation of the gas generator.

[0018] According to one embodiment, the ignition cap abuts a compensating element at its free end; in particular, the end is laterally surrounded by the compensating element. The compensating element delimits the annular combustion chamber at an axial end and mechanically pre-tensions the fuel contained therein. This ensures that the fuel is precisely positioned in the combustion chamber in all positions and orientations of the gas generator and is effectively ignited when the gas generator is activated.

[0019] According to a further embodiment, the outer casing has a circumferential annular flange and exhaust ports located axially between an end wall of the outer casing opposite the igniter and the annular flange. The blowing gas generated during activation flows out in a controlled and effective manner through these exhaust ports.

[0020] According to the invention, a protective device is also provided in a vehicle to solve the aforementioned problem, comprising a gas bag and a gas generator according to the invention for inflating the gas bag. The gas generator is installed in the vehicle such that an end wall of the outer housing associated with the igniter points vertically upwards, and the igniter cap points downwards with the top wall. In other words, the gas generator is installed upside down or inverted by 180°.

[0021] Further advantages and features will become apparent from the following description and the accompanying drawings. These show: - Fig. 1 in a schematic representation a protective device according to the invention with a gas generator according to the invention, - Fig. 2 in a sectional view the gas generator Fig. 1, and - Fig. 3 in a sectional view, an ignition cap of the gas generator made of Fig. 2.

[0022] 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.

[0023] 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.

[0024] In Fig. Figure 1 shows a vehicle 4 standing on a roadway 2 with a vehicle roof 6 that defines a vehicle interior 8 in axial direction A.

[0025] The vehicle 4 has a protective device 10 with a gas bag 12 and a gas generator 20, which is designed to inflate the gas bag 12 when it is activated.

[0026] The gasbag 12, for example, is a head gasbag.

[0027] The gas generator 20, for example, is a single-stage gas generator.

[0028] In the Fig. In the embodiment shown in Figure 2, the gas generator 20 has an outer housing 22, which is composed of a pot-shaped diffuser 24 and a pot-shaped closure body 26 inserted therein.

[0029] The diffuser 24 has an end wall 28, a circumferential ring flange 30 and a substantially cylindrical circumferential wall section 32, which extends in axial direction A between the end wall 28 and the ring flange 30.

[0030] In the circumferential wall section 32 of the diffuser 24, several, for example twelve, outflow holes 34 are formed, which are evenly distributed over the circumference of the diffuser 24 and arranged at an axial height.

[0031] The closure body 26 has an end wall 36 and a circumferential wall section 38, which extends away from the end wall 36 in the opposite direction A and is arranged radially inside the circumferential wall section 32 of the diffuser 24.

[0032] The circumferential wall section 38 of the closure body 26 lies radially inside against the circumferential wall section 32 of the diffuser 24 and is firmly connected to it by means of a circumferential weld 40.

[0033] The pot-shaped diffuser 24 and the pot-shaped closure body 26 are thus arranged nested in opposite directions, so that the inner sides of the end walls 28, 36 are opposite each other, and define the interior 42 of the outer housing 22.

[0034] In the illustrated embodiment, the gas generator 20 is attached to the vehicle roof 6 by means of the ring flange 30, for example by means of screws or bolts, so that the outer surface of the end wall 28 of the diffuser 24 faces the vehicle roof 6. Thus, the outer surface of the end wall 28 of the diffuser 24 points vertically upwards in axial direction A towards the vehicle roof 6, while the outer surface of the end wall 36 of the closure body 26 points downwards in the opposite direction to the axial direction A towards the roadway 2.

[0035] In principle, the gas generator 20 can be mounted in any position or orientation within the vehicle 4. However, in all embodiments, the outer surface of the front wall 28 of the diffuser 24 forms the intended mounting side of the gas generator 20, i.e., the side facing the support to which the gas generator 20 is attached.

[0036] Furthermore, the gas generator 20 has an ignition cap 44 and an electric igniter 46, which are arranged inside 42 of the outer housing 22 and are attached to the closure body 26 via a base 48.

[0037] The base 48 extends through a central opening 50 in the end wall 36 of the closure body 26 and has an electrical connection 52 on the outside, which is electrically connected to the igniter 46.

[0038] The igniter 46 is embedded in the base 48, for example by overmolding or overmolding, and is thus positively connected to it.

[0039] The ignition cap 44 has a first axial end 54, which faces the end wall 36 of the closure body 26, and an axially opposite second axial end 56, which faces the end wall 28 of the diffuser 24 and is closed by a cover wall 58.

[0040] The ignition cap 44 is made in one piece and has a cylindrical, in particular circular cylindrical, circumferential wall 60, which extends in axial direction A from the second axial end 56 to the first axial end 54.

[0041] The ceiling wall 58 is curved or inverted in axial direction A into the interior space 62 enclosed by the circumferential wall 60 and thus forms an inverted section 64 of the ignition cap 44.

[0042] The ignition cap 44, for example, is a deep-drawn part, especially made of metal, and is therefore particularly cost-effective to manufacture.

[0043] The inverted section 64 (see Fig. 3) has a cylindrical inner wall 66 running parallel to the circumferential wall 60 and a central section 68 which extends radially inwards from the inner wall 66.

[0044] The central section 68 is flat in the illustrated embodiment.

[0045] In an alternative embodiment, the central section 68 can be designed essentially arbitrarily, for example concave, i.e. curved towards the interior 62.

[0046] The central section 68 is preferably designed to be free of holes and thus completely closes the circumferential wall 60 at the second axial end 56.

[0047] Furthermore, the central section 68, viewed axially, extends over approximately 60% of the axial cross-sectional area 70 (see Fig. 3) of the interior 62.

[0048] In principle, the central section 68 can extend over any proportion of the axial cross-sectional area 70 of the interior 62, but preferably over at least 50%.

[0049] The inner wall 66 has an axial length h which corresponds to approximately 60% of the axial length H of the ceiling wall 58 or of the inverted section 64.

[0050] In an alternative embodiment, the axial length h of the inner wall 66 is at least 50% of the axial length H of the ceiling wall 58, in particular at least 75%.

[0051] In the illustrated embodiment, the inner wall 66 is spaced apart from the circumferential wall 60 by an annular gap R with a width b greater than zero.

[0052] In alternative embodiments, the inner wall 66 can at least partially abut the circumferential wall 60, whereby the minimum width b of the annular gap R is zero in this case.

[0053] At the first axial end 54 (see Fig. 2) The ignition cap 44 is tightly connected to the base 48.

[0054] For example, when recasting or overmolding the igniter 46, the base 48 can be cast or overmolded onto the ignition cap 44.

[0055] In an alternative embodiment, the ignition cap 44 is attached to the base 48 in axial direction A during assembly and / or glued to it.

[0056] The ignition cap 44 internally defines an ignition chamber 72, to which the igniter 46 axially abuts via an igniter outer wall 74.

[0057] The igniter outer wall 74 is part of the igniter 46 and is cut through when the igniter 46 is activated.

[0058] In all embodiments, the ignition cap 44 is radially surrounded on the outside by an annular combustion chamber 76, which is also limited by the closure body 26 and the diffuser 24.

[0059] The combustion chamber 76 is at least partially filled with a fuel 78, which is in Fig. 2 is schematically represented by several tablets and which, when burned, produces an inflation gas, i.e., a gas which in the present embodiment is provided for inflating the gas bag 12.

[0060] To keep the fuel 78 in a defined and compact state, an elastic compensating element 80 is arranged inside 42 of the outer casing 22, which axially limits the combustion chamber 76 and mechanically preloads the fuel 78 in axial direction A.

[0061] The compensating element 80 is arranged adjacent to the end wall 28 of the diffuser 24 and surrounds the ignition cap 44 radially on the outside at the second axial end 56 sectionally in axial direction A.

[0062] Furthermore, the compensating element 80 borders in axial direction A on the second axial end 56 of the ignition cap 44.

[0063] However, the second axial end 56 of the ignition cap 44 is not attached to the compensating element 80 and forms a free end 82 of the ignition cap 44.

[0064] The ignition chamber 72 is filled with a pyrotechnic booster charge 84, which is located in Fig. 2 is schematically represented by several tablets.

[0065] The amount of pyrotechnic booster charge 84 in the ignition chamber 72 is so large that the pyrotechnic booster charge 84 is adjacent to the igniter 46 in every position of the gas generator 20, especially also in the position shown in the text. Fig. 2 the overhead position shown, in which the gas generator 20 is mounted on the vehicle roof 6 rotated by 180°, or when the gas generator 20 is mounted, for example, on a side wall, rotated by 90° in an alternative embodiment.

[0066] In this context, no pyrotechnic amplifier charge 84 is arranged in the annular gap R.

[0067] Furthermore, the annular gap R or its width b is dimensioned such that no tablets of the pyrotechnic booster charge 84 can “fall” into the annular gap R, i.e., the filling height of the pyrotechnic booster charge 84 extends essentially only to the central section 68 of the ceiling wall 58, particularly when the gas generator 20 is oriented such that the outside of the end wall 36 of the closure body 26 points vertically downwards and the outside of the end wall 28 of the diffuser 24 points axially upwards A.

[0068] The pyrotechnic booster charge 84 is designed to ignite the fuel 78 in the combustion chamber 76 after its ignition by the igniter 46.

[0069] For this purpose, the ignition cap 44 has at least one outlet opening 86, which connects the ignition chamber 72 with the combustion chamber 76 and through which, when the gas generator 20 is activated, the particles and ignition gases formed during the combustion of the pyrotechnic booster charge 84 flow into the combustion chamber 76.

[0070] In the present embodiment, the ignition cap 44 has four outlet openings 86 (see Fig. 3), which are arranged uniformly relative to each other in the circumferential direction, i.e. the four outlet openings 86 are each arranged at an angle of 90° to each other.

[0071] To provide the inflation gas for inflating the protective device 10, the igniter 46 is first activated, thereby igniting the pyrotechnic booster charge 84.

[0072] During the combustion of the pyrotechnic booster charge 84, particles and ignition gas are formed in the ignition chamber 72, which is sealed by the ceiling wall 58.

[0073] This increases the pressure in the ignition chamber 72, causing the particles and the ignition gas to flow through the outlet openings 86 into the combustion chamber 76 and ignite the fuel 78 there.

[0074] In this context, the volume of the ignition chamber 72 remains essentially constant in all phases of the activation of the gas generator 20, as well as before and after activation.

[0075] Furthermore, the ignition cap 44 remains attached to the base 48 during all phases of the activation of the gas generator 20, as well as before and after activation.

[0076] During the combustion of the fuel 78, inflation gas is formed in the combustion chamber 76, which flows radially out of the gas generator 20 via the outflow holes 34 and towards the gas bag 12, inflating it.

[0077] In order to retain particles formed during combustion in the gas generator 20, a filter 88 is arranged between the combustion chamber 76 and the exhaust holes 34, through which the blowing gas flows on its way from the combustion chamber 76 to the exhaust holes 34.

[0078] In this way, a gas generator 20 and a protective device 10 are formed with a gas generator 20 which provides gas particularly reliably after activation.

[0079] Furthermore, the gas generator 20 can be manufactured cost-effectively adapted to various requirements with different booster charges by installing an ignition cap 44 with a correspondingly large ignition chamber 72. Only the axial length H of the inverted section 64 needs to be adjusted, while the external dimensions, in particular the overall axial length of the ignition cap 44, i.e., the axial length between the first and second axial ends 54, 56, remain the same for all ignition caps 44. This ensures that the basic structure of the gas generator 20 is the same for all requirements, and the same components can be used for its manufacture.

Claims

[1] Gas generator (20), in particular for a protective device (10) in a vehicle (4), with an outer casing (22) in the interior (42) of which a combustion chamber (76) is located, an ignition cap (44) surrounded by the combustion chamber (76), which on the inside defines an ignition chamber (72) filled with a pyrotechnic booster charge (84) and is attached to the outer casing (22) via a base (48), and an electric igniter (46) attached to the base (48) and enclosed by an igniter outer wall (74), which is axially adjacent to the ignition chamber (72), wherein the ignition cap (44) has an axially extending cylindrical circumferential wall (60) and a radially extending top wall (58) which closes an axial end (56) of the circumferential wall (60) and which is integrally connected with the circumferential wall (60), characterized by, that the ceiling wall (58) is curved in axial direction (A) into the interior space (62) enclosed by the perimeter wall (60). [2] Gas generator (20) according to claim 1, characterized by , that the ceiling wall (58) is inverted to such an extent that the inverted section (64) has a cylindrical inner wall (66) which runs parallel to the circumferential wall (60) and a central section (68) extending inwards therefrom. [3] Gas generator (20) according to claim 2, characterized by , that the inner wall (66) has an axial length (h) which corresponds to at least 50% of the axial length (H) of the ceiling wall (58), in particular at least 75%. [4] Gas generator (20) according to claim 2 or 3, characterized by , that, viewed axially, the central section (68) closes off at least 50% of the axial cross-sectional area (70) of the interior (62) and / or the central section (68) is planar or concave. [5] Gas generator (20) according to any one of claims 2 to 4, characterized bythat the inner wall (66) is radially in contact with the circumferential wall (60) or is spaced apart from the circumferential wall (60) by an annular gap (R) which is free of pyrotechnic booster charge (84). [6] Gas generator (20) according to any one of the preceding claims, characterized by , that the ignition chamber (72) is filled with the pyrotechnic booster charge (84) at least to such an extent that the pyrotechnic booster charge (84) is adjacent to the igniter (46) in every position of the gas generator (20). [7] Gas generator (20) according to any one of the preceding claims, characterized by , that the circumferential wall (60) has at least one outlet opening (86) through which the ignition chamber (72) is connected to the combustion chamber (76). [8] Gas generator (20) according to any one of the preceding claims, characterized by , that the ceiling wall (58) is closed. [9] Gas generator (20) according to any one of the preceding claims, characterized by, that the volume of the ignition chamber (72) remains constant before, during and after activation of the gas generator (20). [10] Gas generator (20) according to any of the preceding claims, characterized by , that the gas generator (20) is a single-stage gas generator (20). [11] Gas generator (20) according to any of the preceding claims, characterized by , that the ignition cap (44) is attached to the base (48) in such a way that it remains attached to the base (48) even after the gas generator (20) has been activated. [12] Gas generator (20) according to any of the preceding claims, characterized by , that the ignition cap (44) adjoins a compensating element (80) at its free end (82), in particular is laterally surrounded by it, which limits the annular combustion chamber (76) at an axial end and mechanically preloads the fuel (78) contained therein. [13] Gas generator (20) according to any of the preceding claims, characterized by, that the outer casing (22) has a circumferential annular flange (30) and outflow holes (34) which lie axially between an end wall (28) of the outer casing (22) opposite the igniter (46) and the annular flange (30). [14] Protective device (10) in a vehicle (4), comprising a gas bag (12) and a gas generator (20) according to one of the preceding claims for inflating the gas bag (12), wherein the gas generator (20) is installed in the vehicle (4) such that an end wall (36) of the outer housing (22) associated with the igniter (46) points vertically upwards and the ignition cap (44) points downwards with the ceiling wall (58).

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