Actuator for a gas bag module with flow direction reversal in the gas guide

Abstract

Actuator (1) for a gas bag module, comprising a piston (2) having a circumferential flange (3), an igniter unit (4), and a housing (6) having a end wall (7) and a side wall (8), wherein the piston (2) is axially movably mounted in an opening (9) of the end wall (7) and is retractable into the housing (6), wherein the igniter unit (4) is fixedly connected to the housing (6), wherein an intermediate space (11) is formed between the circumferential flange (3) and the end wall (7) of the housing (6), which is fluidly connected or fluidly connectable to the igniter unit (4) by means of a gas guide in order to direct a gas from the igniter unit (4) to the intermediate space (11), wherein the gas guide has at least one separating element (45) which causes a reversal of the gas flow direction by 180° to the direction of gas discharge from the igniter unit (4). enables the piston (2) to be movable in the direction of the igniter unit (4),and wherein the separating element (45) of the gas guide has at least one first opening (20) formed in a side wall of the piston (2), characterized in that the separating element (45) is formed from two components, the piston (2) and a sleeve (24), which are displaceable relative to each other, wherein the separating element (45) has at least one second opening (26) formed in a side wall of the sleeve (24) of the igniter unit (4) and which is fluidly connectable to the first opening (20), wherein the at least one first opening (20) of the piston (2) is larger than the at least one second opening (26) of the sleeve (24), wherein the at least one first opening (20) is arranged displaceably relative to the at least one second opening (26) such that their surfaces projecting onto each other at least partially overlap.

Description

[0001] The invention relates to an actuator for a gasbag module according to the preamble of claim 1. The invention also relates to a gasbag module and a vehicle safety system.

[0002] Occupant restraint systems for motor vehicles, for example, include airbag modules that comprise a gas bag which inflates in the event of an impact to reduce the likelihood of a collision between a vehicle occupant's body parts and a vehicle component. To inflate the gas bag in the event of an impact, gas generators with at least one igniter unit are typically provided. This igniter unit can move a piston, thus forming an actuator. Conventional actuators are configured such that, upon activation of an igniter and the associated release of propellant gas, a piston held within a cylinder housing is pushed out of the cylinder housing. Such actuators can be used, for example, as release devices for retaining straps, whereby the volume of the inflated gas bag can be changed, in particular increased, by releasing the retaining straps.

[0003] Furthermore, so-called pulling or retracting actuators are known. These actuators are configured such that the piston is moved or retracted towards the inside of the housing by the expulsion of a propellant gas generated by an igniter or igniter unit. A pulling actuator with a trigger bolt is known, for example, from DE 10 2009 023 961 A1. The actuator shown there consists of a multitude of components, whereby an igniter carrier is moved along with the actuator when it is triggered. Due to the large number of components, there is a risk of components jamming and thus of the actuator not functioning fully.

[0004] Furthermore, an actuator for a gasbag module is known from the generic patent application DE 39 18 408 A1, wherein the actuator has a piston which has a circumferential flange.The actuator also has an igniter unit and a housing, which has a terminal wall and a side wall, wherein the piston is axially movable in an opening of the terminal wall and retractable into the housing, wherein the igniter unit is fixedly connected to the housing, wherein an intermediate space is formed between the circumferential flange and the terminal wall of the housing, which is fluidly connected or fluidly connectable to the igniter unit by means of a gas guide in order to direct a gas from the igniter unit to the intermediate space, wherein the gas guide has at least one separating element that allows a reversal of the gas flow direction by 180° to the direction of the gas discharge from the igniter unit, wherein the piston is movable in the direction of the igniter unit, and wherein the separating element of the gas guide has at least one first opening which is formed in a side wall of the piston.

[0005] A comparable actuator is also known from the publications DE 10 2012 007 406 A1 and US 4 054 032 A, as disclosed in the publication DE 39 18 408 A1, where the actuators described there are also based on a principle of reversing the flow direction in the gas flow.

[0006] The object of the present invention is to provide an actuator of the type mentioned above that operates as reliably as possible. It is also an object of the invention to provide a gas bag module and a vehicle safety system incorporating such an actuator.

[0007] According to the invention, this problem is solved with regard to the actuator by the subject matter of claim 1, with regard to the gasbag module by the subject matter of claim 7 and with regard to the vehicle safety system by the subject matter of claim 8.

[0008] The invention is therefore based on the idea of ​​providing an actuator for a gas bag module, comprising a piston having a circumferential flange, an igniter unit, and a housing having a end wall and a side wall, wherein the piston is axially movably mounted in an opening of the end wall and is retractable into the housing, wherein the igniter unit is fixedly connected to the housing, wherein an intermediate space is formed between the circumferential flange and the end wall of the housing, which is fluidly connected or fluidly connectable to the igniter unit by means of a gas guide in order to direct a gas from the igniter unit to the intermediate space, wherein the gas guide has at least one separating element that enables a reversal of the gas flow direction by 180° to the direction of gas discharge from the igniter unit, and wherein the piston is movable in the direction of the igniter unit.and wherein the separating element of the gas guide has at least one first opening which is formed in a side wall of the piston.

[0009] The space is thus formed between an axial boundary of the housing, i.e., the end wall, and the side of the circumferential flange facing the end wall. The gas guide, or gas channel, is designed such that the space is fluidly connected to, or capable of being fluidly connected to, the igniter unit. The gas flowing from the igniter unit in a first direction is directed through the separating element into the space, reversing the flow direction. The gas therefore flows in the space in a second direction opposite to the first. Thus, the gas flow direction reverses by 180° from the igniter unit. This exerts a force on the circumferential flange that defines the space, forcing the piston towards the igniter unit. The piston is thereby drawn into the housing, moving relative to the stationary igniter unit.

[0010] The gas flow path extends from the igniter unit, through the separating element, to the intermediate space. In other words, the gas flow path is a gas channel. The flow direction reversal is effected by the separating element. Upon entering the separating element, the flow direction is initially deflected by 90° relative to the gas discharge direction from the igniter unit. The gas exiting the separating element and flowing into the intermediate space is deflected by another 90°, in the simplest case by the radial wall of the intermediate space, i.e., the side wall of the housing. Thus, the gas flows in the intermediate space against the original flow direction after discharge from the igniter unit, resulting in an overall gas flow reversal of 180°. The intermediate space is designed as an annular gap or annular channel, which, when the actuator is activated, pressurizes the circumferential flange across its effective area along its entire circumference.

[0011] According to the invention, the separating element is formed from two components, the piston and a sleeve, which are displaceable relative to each other, wherein the separating element has at least one second opening which is formed in a side wall of the sleeve of the igniter unit and is fluidly connectable to the first opening, wherein the at least one first opening of the piston is larger than the at least one second opening of the sleeve, wherein the at least one first opening is arranged to be displaceable relative to the at least one second opening such that their surfaces projectable onto each other at least partially overlap.

[0012] Preferably, the igniter unit and the piston are arranged coaxially. The longitudinal axis of the piston can thus coincide with the central axis of the igniter unit. This allows for a rotationally symmetrical design, which contributes to the compact construction of the actuator.

[0013] A seal, in particular a sealing ring, can be arranged in the opening of the end wall and / or on the circumferential flange of the piston to prevent gas leakage. The circumferential flange of the piston can have a recess or notch in which the seal, in particular the sealing ring, is arranged.

[0014] In a preferred embodiment, the piston has a cavity with at least one opening, wherein the igniter unit projects through the opening into the cavity and forms a guide for the piston. The igniter unit thus has the dual function of generating the gas required to actuate the piston and guiding its movement. This eliminates the need for additional guide elements, further simplifying the design.

[0015] The piston can be closed on one side and have a closing wall at one axial end, which is positioned opposite the opening for the igniter unit. The circumferential flange can be positioned at the other axial end and adjacent to the opening for the igniter unit.

[0016] If the piston is hollow cylindrical, one side wall of the piston forms a hollow cylinder closed axially on one side with the end wall. The piston, or rather the side wall of the piston, preferably has a circular cylindrical shape.

[0017] It is particularly advantageous to provide several, in particular three, in particular four, in particular five, in particular six, first openings. The first openings are formed in the side wall of the piston. In a further embodiment of the invention, these first openings can be symmetrical about the central or longitudinal axis of the piston.

[0018] As previously described, the separating element consists of two components, a piston and a sleeve, which are movable relative to each other. The separating element has at least one second opening, formed in a side wall of the igniter unit's sleeve and fluidically connected to the first opening. The separating element thus has two openings, one in the piston and the other in the sleeve, allowing gas from the igniter unit to flow through the sleeve and piston into the space between the two openings.

[0019] Preferably, the sleeve has several secondary openings. In particular, the sleeve has at least two openings, at least three openings, at least four openings, at least five openings, or at least six openings. The secondary openings of the igniter unit's sleeve can be arranged symmetrically to the longitudinal axis of the igniter unit.

[0020] As already described, in the actuator according to the invention, the at least one first opening of the piston is larger than the at least one second opening of the sleeve, wherein the at least one first opening is arranged to be displaceable relative to the at least one second opening such that their projectable surfaces at least partially overlap. In other words, the cross-section or diameter of the at least one first opening of the piston is larger than the cross-section or diameter of the at least one second opening of the sleeve of the igniter unit. Thus, a permanent fluid connection between the igniter unit and the space between them is achieved during the stroke of the piston.

[0021] Preferably, the piston and the sleeve of the igniter unit have the same number of openings, or lateral openings. In this case, the piston and the sleeve of the igniter unit are arranged relative to each other such that the respective lateral openings are located in opposite, corresponding positions. The first lateral openings of the piston and the second lateral openings of the sleeve are arranged overlapping. This means that the perpendiculars from the centers of the openings to the central axis of the igniter sleeve or the piston lie on corresponding lines when viewed from above the end wall of the piston.

[0022] Preferably, at least two seals, in particular two sealing rings, are arranged between the sleeve of the igniter unit and the inner side wall of the piston. These sealing rings are preferably arranged above and below the openings so that no gas can escape from the combustion chamber, which is bounded by the sleeve of the igniter unit. This creates a tight fluid connection between the igniter unit and the space between the openings. Since the piston is movably mounted in the opening of the end wall and the gas directed into or flowing into the space cannot escape towards the end wall of the housing, a 180° reversal of the gas flow direction is caused, so that the gas acts on or impacts the top side of the circumferential flange facing the end wall of the housing and moves the piston towards the igniter unit. Due to the 180° reversal of the gas flow direction, the piston is drawn into the housing.

[0023] Preferably, the side wall of the housing has at least one opening through which gas can be supplied and / or discharged to allow pressure equalization. Depending on the size of the at least one opening, rapid venting or a rapid retraction of the piston can be achieved if the opening is chosen to be relatively large. However, if the retraction of the piston is to be dampened, the opening can be chosen to be relatively small in order to provide a certain amount of back pressure on the piston as it retracts.

[0024] The invention is explained in more detail below with reference to several exemplary embodiments and the accompanying illustrations. These show, schematically: Fig. 1: a cross-sectional view of an actuator not according to the invention; Fig. 2: a cross-sectional view of an actuator according to the invention; Fig. 3: a cross-sectional view of an actuator not according to the invention; Fig. 4: a schematic representation of the gas flow in the activated state of the non-inventive actuator according to Fig. 3.

[0025] In Fig. Figure 1 shows an embodiment of an actuator 1 not according to the invention, wherein the actuator 1 has a piston 2 with a circumferential flange 3. The actuator 1 also has an igniter unit 4 with an igniter 5. Furthermore, a housing 6 is provided, wherein this housing 6 has a end wall 7 and a side wall 8. The piston 2 is axially movably mounted in an opening 9 of the end wall 7. The end wall 7 can also be referred to as the front wall of the housing 6. The side wall 8 is designed as the radial boundary of the housing 6, and the end wall 7 as the axial boundary of the housing 6.

[0026] The igniter unit 4 is rigidly connected to the housing 6 and is located inside the housing 6. In the illustrated example, the igniter unit 4 is formed as part of the housing 6. A gap 11 is formed between the circumferential flange 3 and an axial boundary of the housing 6. That is, a gap 11 is formed between the side 10 of the circumferential flange 3 facing away from the igniter unit 4, in particular the igniter 5, and the end wall 7 of the housing 6. In other words, the gap 11 is formed between the side 10 of the circumferential flange 3 facing the end wall 7 of the housing 6, which can also be referred to as the top of the circumferential flange, and the inner surface 12 of the end wall 7. The gap 11 can also be referred to as an annular space or ring-shaped space.

[0027] The intermediate space 11 is fluidly connected or fluidly connectable to the igniter unit 4 by at least one gas guide to direct a gas from the igniter unit 4 to the intermediate space 11, wherein the gas guide has a separating element 45 that causes a reversal of the gas flow direction by 180° relative to the direction of gas discharge from the igniter unit 4, in order to move the piston 2 towards the igniter unit 4 or towards the side 38 of the housing 6 opposite the end wall 7. The illustrated intermediate space 11 is an annular gap or an annular channel through which the circumferential flange 3 can be pressurized over its entire circumference. The piston 2, or a portion thereof, is therefore also part of the separating element 45.

[0028] In the example shown, both the piston 2 and the housing 6 can be rotationally symmetrical, so that both components can have a circular cylindrical shape. The opening 9 of the end wall 7 has a larger diameter than the side wall of the piston, so that the piston 2 is movably mounted in the opening 9.

[0029] In the example shown, the circumferential flange 3 is designed as a ring, which is located on the side of the piston 2 opposite the end wall 14 of the piston 2.

[0030] The side 10 of the circumferential flange 3 facing away from the igniter unit 4 can also be referred to as the side of the circumferential flange 3 facing the inside 12 of the end wall 7 of the housing 6.

[0031] The igniter unit 4 is shown in the illustration. Fig. The igniter unit 4 and the piston 2 are arranged coaxially to the central axis M of the opening 9 of the end wall 7. The piston 2 is also arranged coaxially to the central axis M. Therefore, the igniter unit 4 and the piston 2 are arranged coaxially, i.e., axially aligned, with each other. The piston 2 with the end wall 14 has a cavity 43 with an opening, the igniter unit 4 projecting through the opening into the cavity 43 and forming a guide for the piston 2. The piston 2, with its side wall 13 and the end wall 14, defines a combustion chamber 15. The igniter unit 4 projects into this space 15, which is defined by the side wall 13 and the end wall 14. A sealing ring 16 is arranged around the igniter unit 4. In other words, a sealing ring 16 is located between the outer surface 17 of the igniter unit 4 and the inner surface 18 of the side wall 13 of the piston 2.

[0032] Due to the arrangement of the sealing ring 16, no gas can escape from the combustion chamber 15, with any gas flow being restricted to the designated path via a fluid connection between the combustion chamber 15 and the intermediate space 11. A sealing ring 19 is also provided between the end wall 7 and the side wall 13 of the piston, so that no gas can escape from the intermediate space 11. The sealing ring 19 is preferably arranged in a recess in the wall that delimits the opening 9.

[0033] The piston 2, or rather the side wall 13 of the piston, has two primary and two lateral openings 20, respectively, which are arranged symmetrically to the central axis M. The lateral openings 20 form part of the separating element 45 s of the gas guide, the gas guide connecting the igniter unit 4 and the intermediate space 11 via fluid. The lateral openings 20 are located above the outlet opening 40 of the igniter unit 4. Since the gas cannot escape towards the end wall 7 of the housing and the piston 2 is movably mounted in the opening 9, a 180° reversal of the gas flow direction occurs, causing the gas to impact the upper surface 10 of the circumferential flange 3 and move the piston 2 towards the igniter unit 4 or towards the igniter 5. Starting from the direction of gas discharge from the outlet opening 40, the gas is initially deflected by 90° due to the side openings 20 or the separating element 45.In the space 11 the gas is deflected again by 90°, such that an overall gas flow reversal of 180° is effected in relation to the direction of the gas being discharged from the outlet opening 40 of the igniter unit 4.

[0034] The gas flow and the gas flow reversal by 180° are represented by the arrows.

[0035] The gas flowing into the space 11 and acting on the side 10 of the circumferential flange 3 cannot escape from the space 11 due to the sealing ring 19 of the end wall 7 and the sealing ring 21 attached to the circumferential flange 3. The sealing ring 21 can, for example, be inserted into a recess or indentation of the circumferential flange 3 and seals the circumferential flange against the inner surface 22 of the side wall 8 of the housing 6. A lateral opening 23 is formed in the side wall 8 through which gas can be supplied and / or discharged to equalize pressure.

[0036] In Fig. Figure 2 shows the only embodiment of the actuator 1 according to the invention. Corresponding reference numerals are given for identical and matching components and elements, with the explanations regarding corresponding features being derived from Fig. 1 also on the embodiment according to Fig. 2 are transferable.

[0037] In the only embodiment belonging to the invention according to Fig. The igniter unit 4 has a sleeve 24 which projects into the cavity 43 of the piston 2, defining a combustion chamber 25 and forming the guide for the piston 2. The sleeve 24 has two secondary or lateral openings 26, which form part of the separating element 45 and serve as a fluid connection or gas guide from the igniter unit 4, in particular from the combustion chamber 25 of the igniter unit, to the intermediate space 11. The diameters of the secondary or lateral openings 26 of the sleeve 24 are smaller than the diameters of the primary or lateral openings 20 of the side wall 13 of the piston 2. The lateral openings 26 of the sleeve are aligned with the lateral openings 20 of the piston 2.

[0038] The separating element 45 is used in Fig. The piston 2 is formed from two components: the piston 2 with a first opening 20 and the sleeve 24 with a second opening 26. Both components are displaceable relative to each other such that gas from the combustion chamber 25 can first pass through the openings 26 of the sleeve and then through the openings 20 of the piston 2 into the space 11. The gas cannot escape from the space 11 towards the end wall 7 of the housing 6. To prevent gas from escaping in this area, a sealing ring 19 is provided, which is installed in the opening of the end wall 7 and creates a seal between the end wall 7 of the housing 6 and the side wall 13 of the piston 2. Additionally, the side wall 13 has a shoulder 27.Due to this section 27, the piston 2 can only be moved to a limited extent towards the end wall 7, since the section 27 is designed such that the side wall 13 of the piston 2 has a larger diameter in this area than the opening 9 of the end wall 7. The section 27 thus abuts the inner surface 12 of the end wall 7. An opening 42, which is formed in the end wall 14 of the piston 2, serves for pressure equalization.

[0039] Furthermore, a sealing ring 21 is provided on the circumferential flange 3 of the piston 2, ensuring a seal between the inner surface 22 of the side wall 8 of the housing 6 and the circumferential flange 3. In addition to the sealing ring 16, which is associated with the igniter unit 4, another sealing ring 28 is provided for the sleeve 24 of the igniter unit 4. Accordingly, the sealing ring 16 is located above the lateral openings 20 of the piston 2, and the sealing ring 28 is located below the lateral openings 20 of the piston 2. The sealing rings 16 and 28 are preferably fixed or attached to the inner surface 18 of the side wall 13 of the piston 2. Since the sealing rings 16 and 28 are located above and below the lateral openings 20 and 26, respectively, the gas from the combustion chamber 25 can be directed through the openings 26 and 20 into the intermediate space 11.Gas leakage in the area of ​​the sleeve 24 of the igniter unit 4 is prevented by the sealing rings 16 and 28, and a permanent fluid connection from the igniter unit 4 to the space 11 is provided over the entire stroke of the piston 2.

[0040] The direction of gas flow and its 180° reversal of direction can be seen from the arrows shown. Starting from the direction of gas discharge from the outlet opening 40, the gas is initially deflected by 90° due to the lateral openings 26, which form part of the separating element 45. In the space 11, the gas is deflected again by 90°, resulting in a total 180° reversal of gas flow relative to the direction of gas discharge from the outlet opening 40 of the igniter unit 4.

[0041] Also according to the in Fig. In the embodiment shown in Figure 2, the gas acts on the upper surface 10 of the circumferential flange 3, causing the piston 2 to move downwards, i.e., towards the igniter 5. The space 11 is an annular gap or channel that pressurizes the circumferential flange 3 around its entire circumference. In other words, the piston 2, or the circumferential flange 3, is moved towards the side 38 of the housing 6, which is located opposite the end wall 7 of the housing 6.

[0042] In Fig. Figure 3 shows an embodiment of the actuator 1 that is not part of the invention. Identical reference numerals are used for components and elements that function identically or have the same meaning. The corresponding explanations from Fig. 1 and Fig. 2 can refer to the components and elements of the embodiment according to Fig. 3. The references should be transferred accordingly.

[0043] In the illustrated example, the actuator 1 has a bypass sleeve 29, which also forms the separating element 45. This bypass sleeve 29 consists of an end wall 30 and a side wall 31. An opening 39 is formed on the side of the bypass sleeve opposite the end wall 30. The piston 2, in particular the circumferential flange 3 of the piston, is axially movable within the bypass sleeve 29. A gap 32, or an annular gap, is formed between the bypass sleeve 29, in particular the side wall 31 of the bypass sleeve, and the housing 6, in particular the inner surface 22 of the housing 6. The side wall 31 of the bypass sleeve has a smaller diameter than the side wall 8 of the housing 6. This gap 32 serves as a gas guide or gas channel between the igniter unit 4 and the intermediate space 11.Gas is thus directed from the combustion chamber 33 via the gap 32 to the intermediate space 11, whereby the two illustrated lateral openings 41 in the bypass sleeve 29, which fluidly connect the igniter unit and the intermediate space 11, represent a part of the separating element 45. The piston 2 is hollow, with the opening 42 in the piston 2 serving for pressure equalization.

[0044] Since the gas cannot escape from the space 11 towards the end wall 7, a 180° reversal of the gas flow direction occurs, causing the gas to act on the top 10, or on the side 10 facing away from the igniter unit 4, or on the side 10 of the circumferential flange 3 facing the end wall 7 of the housing 6. As a result, the piston 2 is moved towards the igniter unit 4. In this case, the piston moves towards the end wall 30 of the bypass sleeve. To prevent gas from escaping from the space 11 towards the end wall 7, a sealing ring 19 is provided. Furthermore, the end wall 7 and the side wall 13 of the piston 2 have a special, mutually coordinated shape. In this case, a shoulder 27 is formed, which prevents the piston 2 from being forced out of the opening 9 of the end wall 7.

[0045] Out of Fig. Figure 3 further shows that the circumferential flange 3 can have a notch 21a in which the sealing ring 21 is located. Therefore, the gas directed into the space 11 cannot escape laterally of the circumferential flange 3 towards the end wall 30 of the bypass sleeve 29.

[0046] In Fig.Figure 4 schematically illustrates the process involving an activated actuator 1 not belonging to the invention. First, an electrical pulse 34 is generated and transmitted to the igniter 5. This results in ignition and gas generation 35 in the combustion chamber 33. The gas is then directed through the gap 32, in the form of an outer gas flow section (A), via the lateral openings 41 of the bypass sleeve 29 into the intermediate space 11. Thus, a gas flow occurs between the housing 6 and the bypass sleeve 29 in the outer gas flow section (A). After the gas has passed through the lateral openings 41 of the bypass sleeve 29 and entered the intermediate space 11, pressure is applied to the piston 2, in particular to the circumferential flange 3 of the piston 2, so that the piston 2 is moved downwards in the direction of the schematic arrow 37, i.e., towards the igniter 5 or the igniter unit 4.Simultaneously, after the outer gas flow section (A) has passed through the lateral openings 41 of the bypass sleeve 29, it is deflected into a further inner gas flow section (I), whereby the gas flow direction is reversed by 180°. The outer gas flow section (A) and the inner gas flow section (I) run in opposite directions and essentially parallel to each other. The direction of gas flow and its 180° reversal can be deduced from the arrows shown. Starting from the gas's discharge direction, the gas flow is initially deflected by 90° due to the separating element 45 and the lateral openings 41. In the space 11, the gas flow is deflected again by 90°, resulting in a complete 180° reversal of the gas flow relative to the original discharge direction. Reference symbol list 1 actuator 2 pistons 3 circumferential flange 4 ignition units 5 lighters 6 cases 7 End wall 8 side wall 9 Opening in end wall 10. Side of the circumferential flange 11 space 12 Inside of the end wall 13. Side wall of the piston 14 End wall of the piston 15 Combustion chamber piston 16 Sealing ring igniter unit 17 Outer surface of ignition unit 18 Inside side wall piston 19 Sealing ring end wall 20 side opening piston 21 Sealing ring circumferential flange 21a Notch in circumferential flange 22 Inside side panel housing 23 side opening side wall housing 24-sleeve ignition unit 25 Combustion chamber igniter sleeve 26 side opening sleeve 27 Paragraph Side wall piston 28 Sealing ring sleeve igniter unit 29 Bypass sleeve 30 End wall bypass sleeve 31 Side wall bypass sleeve 32 gaps 33 Combustion chamber 34 electrical impulse 35 Ignition and Gas Production 36 Pressure build-up at the piston 37 Movement of piston 38 opposite the end wall of the housing 39 Opening Bypass sleeve 40 Outlet Igniter Unit 41 lateral opening bypass sleeve 42 Pressure equalization opening 43 Cavity 45 separating element M Central axis of opening 9 in end wall 7 I Inner gas flow section A Outer gas flow section

Claims

[1] Actuator (1) for a gas bag module, comprising a piston (2) having a circumferential flange (3), an igniter unit (4) and a housing (6) having a end wall (7) and a side wall (8), wherein the piston (2) is axially movably mounted in an opening (9) of the end wall (7) and is retractable into the housing (6), wherein the igniter unit (4) is fixedly connected to the housing (6), wherein an intermediate space (11) is formed between the circumferential flange (3) and the end wall (7) of the housing (6), which is fluidly connected or fluidly connectable to the igniter unit (4) by a gas guide in order to direct a gas from the igniter unit (4) to the intermediate space (11), wherein the gas guide has at least one separating element (45) which causes a reversal of the gas flow direction by 180° to the direction of gas discharge from the igniter unit. (4) enables the piston (2) to be movable in the direction of the igniter unit (4),and wherein the separating element (45) of the gas guide has at least one first opening (20) which is formed in a side wall of the piston (2), characterized by , that the separating element (45) is formed from two components, the piston (2) and a sleeve (24), which are displaceable relative to each other, wherein the separating element (45) has at least one second opening (26) which is formed in a side wall of the sleeve (24) of the igniter unit (4) and is fluidly connectable to the first opening (20), wherein the at least one first opening (20) of the piston (2) is larger than the at least one second opening (26) of the sleeve (24), wherein the at least one first opening (20) is arranged displaceably relative to the at least one second opening (26) such that their surfaces projectable onto each other at least partially overlap. [2] Actuator (1) according to claim 1, characterized by , that the igniter unit (4) and the piston (2) are arranged coaxially. [3] Actuator (1) according to claim 1, characterized by , that the igniter unit (4) and the piston (2) are arranged in the opening (9) of the end wall (7). [4] Actuator (1) according to claim 1, characterized by , that a seal (21) is arranged on the circumferential flange (3) of the piston (2). [5] Actuator (1) according to any of the preceding claims, characterized by , that the piston (2) has a cavity (43) with an opening, wherein the igniter unit (4) projects through the opening into the cavity (43) and forms a guide for the piston (2). [6] Actuator (1) according to any of the preceding claims, characterized by , that the side wall (8) of the housing (6) has at least one opening (23) through which gas can be supplied and / or discharged to allow pressure equalization. [7] Gasbag module with an actuator (1) according to one of the preceding claims. [8] Vehicle safety system comprising an actuator (1) or a gas bag module according to any of the preceding claims.

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