Safety device in vehicle

Abstract

A safety device in a vehicle is provided. The safety device comprises a modular actuator (100) comprising a housing (1) having a first end (2), a piston (4) adapted to be mounted in the housing (1) and configured to move from a retracted position to an extended position, and a gas generator (15). The piston (4) has a first end forming a pressure surface (6) facing the first end (2) of the housing (1). A gas chamber (8) is formed between the pressure surface (6) of the piston (4) and an inner wall of the first end (2) of the housing (1), and the gas generator (15) is located in the gas chamber (8). The volume of the gas chamber (8) as seen in a state in which the piston (4) is in the retracted position is selectively adaptable by: replacing a piston (4) having a first volume with a piston having a second volume, the second volume being different from the first volume; and / or a spacer (25) is arranged in the gas chamber (4).

Description

Technical Field

[0001] The invention relates to a safety arrangement in a vehicle, the safety arrangement comprising a modular actuator. Background Art

[0002] It is well known in the art that actuators are used in safety devices in motor vehicles, these actuators are formed by pistons, which are moved from a retracted position to an extended position by gas generated by a gas generator. One example is the use of a hood lifter to lift the hood or bonnet of a vehicle in order to provide protection for a pedestrian struck by the vehicle. It has been observed that if a motor vehicle strikes a pedestrian, the bumper of the vehicle will often strike the legs or lower torso of the pedestrian. Therefore, the legs of the pedestrian will usually be pushed in the direction of travel of the vehicle, and the head and upper torso will usually tilt towards the hood and windshield of the vehicle. This tilting movement often causes the head or upper torso of the pedestrian to first contact the hood, and thereafter, if the impact force from the impact is strong enough and the vehicle continues to move forward, it also contacts the windshield. In order to minimize the damage to pedestrians caused by such impacts as described above, motor vehicles are usually provided with so-called hood lifting arrangements. These arrangements are usually configured so that the rear part of the hood (i.e., the part closest to the windshield) is lifted by one or more actuators. In the event of a vehicle striking a pedestrian, the hood will generally provide an effective, flexible impact energy absorbing structure. However, if the hood is not raised, there is a higher risk that the hood will deform to the extent that hard, non-flexible parts beneath the hood (such as the engine block) come into contact with the hood and an undesirable, rigid impact may result from a collision between the pedestrian and the vehicle. Additionally, raising the rear portion of the hood will further tilt the surface of the hood and help reduce the speed at which a body moves toward the windshield. Furthermore, the smaller acute angle between the windshield and the hood will also help to reduce the severity of a person struck by a vehicle.

[0003] Depending on the intended application and the design of the vehicle or vehicle part, it is sometimes necessary to vary the characteristics of the actuator in terms of the force applied by the piston versus time or the stroke length versus time. Another parameter that may be specific to a given application is the stroke length of the piston. This is usually achieved by providing a range of actuators of different sizes and also by varying the pyrotechnic load of the gas generator. However, this is expensive because each size requires separate tools etc. to provide the housing and piston.

[0004] There is therefore a need for an easier way to provide an actuator with different characteristics depending on the intended application. Summary of the invention

[0005] It is an object of the present invention to provide a safety device using an actuator, wherein the actuator has a design that allows the characteristics of the actuator to be adapted to the specific application.

[0006] Another object is to provide a safety device comprising an actuator which allows easy adaptation of eg force, speed and stroke length, thereby allowing the characteristics of the safety device to be adapted to the specific application.

[0007] These and other objects that will be apparent from the following summary and description are achieved by a safety device in a vehicle, the safety device comprising a modular actuator including a housing having a first end, a piston adapted to be mounted in the housing and configured to move from a retracted position to an extended position, and a gas generator, wherein

[0008] The piston has a first end forming a pressure surface facing the first end of the housing, whereby a gas chamber is formed between the pressure surface and the inner wall of the first end of the housing, the gas generator being fluidly connected to the gas chamber; and wherein

[0009] The volume of the gas chamber as seen in the state when the piston is in the retracted position can be selectively adapted by:

[0010] replacing a piston having a first volume with a piston having a second volume, the second volume being different from the first volume; and / or

[0011] A spacer is arranged in the gas chamber.

[0012] Thus, a safety device is provided comprising a modular actuator, wherein the volume of the gas chamber, as seen in the state when the piston is set to its retracted position, can be varied to allow the characteristics of the actuator to be adapted to the intended application. For example, the force with which the piston contacts an intended impact surface, such as the bonnet of a motor vehicle, can be adapted, or the time taken to tension a seat belt can be adapted. The time required to reach a particular stroke length of the piston can also be adapted based on the intended application. All of this can be achieved by relying on a single housing size and providing the housing with different interchangeable piston designs, piston sizes and also one or more spacers. This not only makes it possible to tailor an actuator to meet a particular application, but also makes it possible to reduce costs in terms of the number of different actuators that must be supplied to the market.

[0013] The piston may include an axially extending recess having a mouth facing the first end of the housing.

[0014] In one embodiment, the recess may have a uniform cross-section along its axial extension. In another embodiment, the recess may have a cross-section that tapers towards the second end of the housing.

[0015] The recess can be used to increase the volume of the gas chamber compared to a uniform piston received in a cylindrical housing. The recess can also be used to increase or reduce the pressure surface of the piston, i.e. the surface of the piston impacted by the gas generated by the gas generator when the gas generator is deployed. The recess can also be used to receive one or more spacers. Furthermore, the recess can be used to support the gas generator. All of these aspects can be used independently of each other to influence the characteristics of the actuator to meet specific applications while using the same housing.

[0016] The gas generator may be arranged in the recess. In one embodiment, the recess may be used to fix the gas generator to the piston. The fixation may be achieved, for example, by press fitting or by bonding.

[0017] The spacer may be disposed within the recess of the piston, and the piston may move relative to the spacer when the piston moves from the retracted position to the extended position.

[0018] The modular actuator can be provided with a range of different spacers having different volumes and geometries. Thus, the volume of the gas chamber within the same housing can be adapted to thereby meet the specific application of the actuator. Two or more spacers can be combined to provide the desired volume of the gas chamber.

[0019] The piston may be made of a plastic material. The piston may be formed by injection molding or by 3D printing.

[0020] By injection molding or 3D printing, the piston can be given a complex geometry, allowing for example the formation of one or more recesses, which can be used in different ways depending on the desired effect. For example, one or more recesses can be used to fix the gas generator in different positions in the gas chamber relative to the housing. Thus, when the gas generator is deployed, the force applied by the gas generator to the pressure surface of the piston can be adapted.

[0021] The one or more recesses may be arranged to provide the gas chamber with a given volume as seen in a state when the piston is in its retracted position. The one or more recesses may also be used to fix one or more spacers to the piston, thereby providing the gas chamber with a given volume as seen in a state when the piston is in its retracted position.

[0022] In addition, one or more recesses can be used to provide the piston with a customized contact surface with the inner wall of the housing. Thus, the recess can be along the interior of the piston, but can also be formed as one or more grooves in the outer envelope surface of the piston. These grooves can better control the friction between the piston and the housing when the piston moves from the retracted position to the extended position. The friction can, for example, be used to control the speed characteristics of the piston when the gas generator is deployed.

[0023] The modular actuator may further include a power connector configured to supply power to the gas generator, the power connector being connected to a support element of the piston, the support element protruding outside the housing.

[0024] In the case where the power connector is arranged outside the housing and the gas generator is arranged in the gas chamber inside the housing, the connecting wire can extend between the gas generator and the power connector to supply power to the gas generator. The connecting wire can be arranged to extend along a groove in the outer wall portion of the piston, or to extend in a channel arranged inside the piston.

[0025] The modular actuator may further comprise a power connector configured to supply power to the gas generator, the power connector being arranged adjacent to the bottom wall of the housing.The power connector may be configured to be connected to the gas generator via an opening in the bottom wall of the housing.

[0026] The housing may be formed by deep drawing a metal material. Deep drawing allows the housing to be easily manufactured without requiring any welding to form lugs or the like that are typically used to secure the actuator to the vehicle. Furthermore, since the housing may be formed without welding, there is no risk of introducing cracks or tensions in the material that are associated with welding.

[0027] In one embodiment, the safety device may be a hood lifter in a vehicle.

[0028] In one embodiment, the safety device may be a seat belt pretensioner.

[0029] In one embodiment, the safety device may be a seat structure reinforcement. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be described in detail with reference to the schematic drawings.

[0031] Figure 1 A schematic cross-section of a modular actuator according to one embodiment of the present invention is disclosed.

[0032] Figure 2a to Figure 2c Three different schematic cross-sections of a modular actuator according to the invention with three pistons having recesses of different depths are disclosed.

[0033] Figure 3 A schematic cross-section of a modular actuator using spacers according to the present invention is disclosed.

[0034] Figure 4 A schematic cross-section of another modular actuator using a piston with a recess and a top-mounted gas generator according to the present invention is disclosed.

[0035] Figure 5A schematic cross-section of yet another modular actuator using a piston with a recess and a top-mounted gas generator according to the present invention is disclosed.

[0036] Figure 6 Highly schematically disclosed are graphs of piston force versus time and stroke length versus time for a piston with a small volume gas chamber and different pyrotechnic load combinations.

[0037] Figure 7 Highly schematically disclosed are graphs of piston force versus time and stroke length versus time for a piston with a large volume gas chamber and different pyrotechnic load combinations. DETAILED DESCRIPTION

[0038] Now go to Figure 1 , discloses a schematic cross-section of one embodiment of a safety device having a modular actuator 100. The actuator 100 is disclosed with its piston in a fully retracted position.

[0039] The modular actuator 100 comprises a housing 1 in the form of a hollow cylinder having a first end 2 and a second end 3. The housing 1 may be formed of a deep drawn metal material. The first end 2 is a closed end. The housing 1 contains a piston 4. The piston 4 is disclosed as having a portion 5 extending from the housing 1 via the second end 3 of the housing 1. It should be understood that the piston 4 maintaining the functionality of the present invention may also be of a type in which the piston 4 is completely contained in the housing 1 when the piston 4 is in its fully retracted position.

[0040] The piston 4 is mounted in the housing 1. The piston 4 can be axially moved from a retracted position to a fully or substantially fully extended position within the housing 1. The retracted position is the default position of the piston 4.

[0041] The piston 4 has a pressure surface 6 facing the first end 2 of the housing 1. The pressure surface 6 generally has an outer cross-sectional area and an outer cross-sectional geometry that substantially corresponds to the inner cross-sectional area and the inner cross-sectional geometry of the housing 1. Thus, the inner wall 7 of the housing 1 together with the pressure surface 6 of the piston 4 partially define a gas chamber 8. The volume of the gas chamber 8 may vary depending on the instantaneous axial position of the piston 4 within the housing 1. When the piston 4 is in its fully retracted position, the gas chamber 8 has its minimum volume, and when the piston 4 is in its fully extended position, the gas chamber has its maximum volume.

[0042] The envelope surface 9 of the piston 4 supports a sealing ring 10 which sealingly abuts an axial portion of the inner wall 7 of the housing 1. The sealing ring 10 is housed in a circumferential recess 11 in the envelope surface 9 of the piston 4.

[0043] An end portion 12 of the housing 1 adjacent to the second end 3 of the housing 1 comprises a neck portion 13 having a locally reduced cross-sectional area. An edge portion 14 of the piston 4 opposite the pressure surface 6 is configured to abut against said neck portion 13 when the piston 4 is set to its fully extended position. Thereby, a physical stop is formed which prevents the piston 4 from falling out of the housing 1.

[0044] The modular actuator 100 also includes a gas generator 15. In the disclosed embodiment, the gas generator 15 is located in the gas chamber 8. In the disclosed embodiment, the gas generator 15 is disclosed as being received in an axially extending recess 16 of the piston 4 and is therefore supported by the piston 4. In an alternative embodiment not shown, the gas generator 15 can be arranged adjacent to the first end 2 of the housing 1. Therefore, the gas generator 15 does not have to be supported by the piston 4. Regardless of the location of the gas generator 15, the gas chamber 8 is defined by the inner wall 7 of the housing 1, the inner wall 17 of the recess 16, the pressure surface 6 of the piston 4, and the gas generator 15.

[0045] In the disclosed embodiment, the gas generator 15 is indirectly connected to a power connector 18. The power connector 18 is arranged outside the housing 1 and supported by the portion 5 of the piston 4 extending from the housing 1. In this embodiment, the power connector 18 is designed to communicate with the gas generator 15 and supply power to the gas generator via a wire arrangement 19, which extends along the axial extension of the piston 4 and thus extends within the housing 1. The wire arrangement 19 can be arranged in one or more recesses 24a, 24b in the outer envelope wall of the piston 4. The wire arrangement 19 has a first set of terminals 20 connected to terminals 21 of the power connector 18 and a second set of terminals 22 connected to terminals 23 of the gas generator 15.

[0046] Conversely, when the gas generator 15 is arranged adjacent to the first end 2 of the shell 1, the power connector 18 can be arranged on the first end 2 of the shell 1 and communicate with the gas generator 15 via an opening in the first end 2 of the shell 1 and power the gas generator.

[0047] Regardless of the location, the power connector 18 is configured to be connected to the electronic control unit ECU (not shown) of the vehicle in a manner known in the art. In the event that the ECU, via the crash sensor and the processor integrated in the ECU, should determine that there is an emergency situation to be responded to, such as a frontal collision, an activation signal is transmitted to the igniter of the gas generator 15, which will cause the gas generator to deploy. The gas generator 15 will in turn generate a volume of gas at a pressure much higher than the ambient pressure. The gas acts on the pressure surface 6 of the piston 4 and forces the piston 4 to move in the axial direction from its retracted position to its extended position.

[0048] According to the invention, the piston 4 is preferably made of a plastic material. The piston 4 is preferably formed by injection molding or by 3D printing. By injection molding or 3D printing, the piston 4 can be given a complex geometry, thereby allowing, for example, one or more recesses 16 to be formed, which can be used in different ways depending on the desired effect. The recess 16 can, for example, be part of the gas chamber 8.

[0049] A combination of multiple different embodiments and different features will be illustrated below. For example, one or more recesses 16, 24a, 24b can be used to fix the gas generator in the gas chamber relative to the housing at different positions to reduce the friction between the piston 4 and the inner wall of the housing 1 or to accommodate the wire arrangement 19. The central recess 16 can be arranged to provide the gas chamber 8 with a given volume as seen in the state when the piston is in its retracted position, and also reduce weight. The central recess 16 can also be used to fix one or more spacers as described below to the piston 4, thereby providing the gas chamber 8 with a given volume as seen in the state when the piston 4 is in its retracted position. In addition, one or more recesses 16, 24a, 24b can be used to provide the piston 4 with a customized contact surface with the inner wall of the housing 1. Therefore, the recesses 16, 24a, 24b can be formed along the inside of the piston 4, but can also be formed as one or more grooves in the outer envelope surface of the piston 4. When the piston moves from the retracted position to the extended position, these grooves can better control the friction between the piston and the housing. Friction can, for example, be used to control the velocity characteristics of the piston when the gas generator is deployed.

[0050] In the following, it will be described how the characteristics of the modular actuator 100 and thus of the safety device can be changed according to the invention.

[0051] from Figure 2a to Figure 2c Initially, one way to change the characteristics of the modular actuator 100 is by changing the volume of the gas chamber 8 . Figure 2a to Figure 2c A simplified model of a modular actuator 100 according to the present invention is disclosed. For ease of understanding, the power connector has been omitted. Furthermore, the wire arrangement extending between the power conductor and the generated gas has been omitted. Figure 2a to Figure 2c The same housing 1 is disclosed, provided with three different pistons 4a to 4c.

[0052] The housing 1 can be formed by deep drawing of a metal material. Deep drawing allows the housing to be easily manufactured without requiring any welding to form lugs or the like that are usually used to secure the actuator to the vehicle. Furthermore, since the housing can be formed without welding, there is no risk of introducing cracks or tension in the material.

[0053] All pistons 4a to 4c have the same external dimensions (i.e. the same length), therefore have the same available stroke length, and also have the same external cross-sectional dimensions. The three pistons 4a to 4c are all provided with internal axially extending recesses 16a to 16c, which extend from the pressure surface 6a to 6c facing the first end 2 of the housing 1 toward the second end 3 of the housing 1. The recesses 16a to 16c have a mouth facing the first end of the housing. In all three embodiments, the recesses 16a to 16c have the same inner diameter. In addition, in all three embodiments, the gas generator 15 is arranged in the recesses 16a to 16c and is connected to the bottom of the recess. The gas generator 15 can be fixed in the recess, for example, by press fitting or by bonding.

[0054] The axial depth of the recesses 16a to 16c differs between the three embodiments. Thus, the volume of the gas chamber 8 (which volume is defined between the inner wall 7 of the housing 1, the pressure surfaces 6a to 6c of the pistons 4a to 4c and the gas generator 15 received in the gas chamber) can be changed simply by replacing a piston having a first volume (i.e., the first size of the recess) with a piston having a second volume (i.e., the second size of the recess).

[0055] The different volumes of the pistons 4a to 4c and the different distances between the pressure surfaces 6a to 6c and the location of the gas generator 15 for the three pistons 4a to 4c result in different impact forces between the generated gas flow and the pressure surfaces 6a to 6c. This results in different characteristics of the resulting actuator when applied in a vehicle in the event of a collision. The larger the gas chamber volume, the smaller the impact force. In addition, the larger the gas chamber volume, the longer it takes for the piston to reach its fully extended position.

[0056] like Figure 2a to Figure 2c As disclosed in , the recesses 16a to 16c have a uniform cross section along their axial extension. In another embodiment, the recesses 16a to 16c may have a cross section that tapers towards the second end 3 of the housing 1 . Figure 5 One such embodiment is disclosed in , which will be discussed further below.

[0057] The recesses 16a to 16c can be used to increase the volume of the gas chamber 8 compared to a uniform solid piston received in a cylindrical housing. In yet another embodiment, the recesses 16a to 16c can be used to control the pressure surface 6a to 6c of the piston, i.e. the surface of the piston impacted by the gas generated by the gas generator when deployed. All of these aspects can be used independently of each other to influence the characteristics of the actuator to meet specific applications.

[0058] Not only the geometry and volume of the gas chamber 8 can be varied to change the characteristics of the modular actuator 100. As part of the modularity, gas generators 15 of different pyrotechnic loads can also be arranged in the piston 4. Thereby, the amount of gas, in particular the pressure of the gas generated when the gas generator is deployed, can be varied according to the desired characteristics.

[0059] Now go to Figure 3 , discloses another embodiment of a modular actuator 100 for a safety device. The housing 1 has the same Figure 2a to Figure 2c The housing 1 is of exactly the same size and design as described in the previous section. In addition, the piston 4 has the same Figure 2a to Figure 2c The same design as described in , with an axially extending recess 16. Figure 3 Implementation plan and Figure 2a to Figure 2c The difference of the disclosure of is that the recess 16 is provided with a spacer 25. The spacer 25 is coaxially arranged in the recess 16.

[0060] When the piston 4 moves from the retracted position to the extended position, the piston 4 is movable relative to the spacer 25. Therefore, the spacer 25 is slidably received in the recess 16. In addition, the spacer 25 is disclosed as being arranged adjacent to the inner bottom wall 26 of the housing 1. Therefore, in this embodiment, the gas chamber 8 is defined by the inner wall 27 of the recess 16, the end of the spacer 25 facing the second end 3 of the housing 1, and the piston-supported gas generator 15.

[0061] In the deployed state of the gas generator 15, the generated gas will act on the end of the spacer 25 facing the second end 3 of the housing 1. This will force the piston to move from its retracted position to its extended position by the piston moving axially inside the housing 1 and along the outer envelope wall 28 of the spacer 25.

[0062] Thus, in this embodiment, there is a relative movement between the spacer 25 and the piston 4 .

[0063] The modular actuator may be provided with a series of different spacers 25 having different volumes, different axial lengths and geometries. It should be understood that the spacer 25 does not have to be arranged flush with the bottom wall 26 of the housing 1. In addition, the recess 16 may be provided with two or more spacers, which are arranged one after the other in the recess to provide the desired volume of the gas chamber.

[0064] Thus, by using one or more spacers, the volume of the gas chamber within a single housing may be adapted to suit the particular application of the actuator.

[0065] Now go to Figure 4 , describes another embodiment of a modular actuator 100 according to the present invention. The housing 1 has the same Figure 2a to Figure 2c. However, as an essential difference, the gas generator 15 as well as the power connector 18 connected to the gas generator 15 are supported by the piston 4 in a position outside the housing 1. The gas generator 15 and the power connector 18 are connected to a support element 27 of the piston 4. The support element 27 protrudes outside the housing 1. The power connector 18 and the gas generator 15 are arranged in a position offset from the longitudinal center line of the piston 4 so as not to come into contact with, for example, the hood in the case where the modular actuator is used as part of a safety device (i.e. a hood lifter).

[0066] The piston 4 has a generally cylindrical outer envelope wall having a uniform diameter along its entire extension. The pressure surface 6 of the piston 4 facing the first end 2 of the housing 1 has a locally increased diameter to form a guide portion, which is configured to slide against the inner wall 7 of the housing 1. The guide portion is provided with a circumferentially extending recess 11, which in turn supports the sealing ring 10. The piston 4 is slidingly received in the housing 1 and has an internal channel 29 extending along the axial extension of the piston 4. The channel 29 contains a coaxially extending spacer 25. The spacer 25 has an internal channel 30 extending along the entire axial extension. The first free end of the channel 30 of the spacer 25 faces the gas generator 15, while the second free end of the channel of the spacer 25 faces the first end 2 of the housing 1. Thus, the gas chamber 8 is defined by the channel 29 in the piston 4, the channel 30 of the spacer 25, the gas generator 15 and the wall 26 of the second end 2 of the housing 1. Thus, by providing one or more spacers of different lengths, different diameters of the passage 30 of the spacer 25, the volume of the gas chamber 8 can be varied. Thus, the volume of the gas chamber 8 within a single housing 1 can be adapted to meet the specific application of the actuator. Two or more spacers 25 can be combined along the axial extension to provide the desired volume of the gas chamber 8.

[0067] Now turn to Figure 5 , describes another embodiment of a modular actuator 100 according to the present invention. The modular actuator 100 has Figure 4 The actuator in is of generally the same design, wherein the gas generator 15 and the power connector 18 are supported by the piston 4 in a position outside the housing 1 .

[0068] Piston 4 and Figure 4 The piston 4 of 1 is different in that it has a conical shape that tapers towards the second end 3 of the housing 1. The piston 4 comprises an internal channel 29 that extends along the axial extension of the piston 4. The channel 29 has a first conical portion 31 that tapers towards the second end 3 of the housing 1. The first conical portion 31 merges with a second portion 32 facing the first end 2 of the housing 1. Thereby, the gas chamber 8 is defined by the inner wall of the channel 29 in the piston 4, the gas generator 15 and the wall 26 of the first end 2 of the housing 1.

[0069] As Figure 4 Another difference compared to the embodiment of the present invention is that the gas generator 15 is smaller. Therefore, as part of the present invention, regardless of the design of the housing 1, the piston 4 and the spacer 25, the type of gas generator 15 and its pyrotechnic load can also be adapted to meet the specific application of the actuator.

[0070] Now turn to Figure 6 , shows a graph illustrating different characteristics that can be achieved by a modular actuator according to the invention. The same actuator with a small gas chamber is used. In the tests, the actuator was provided with three different gas generators with different pyrotechnic loads: 130 mg, 270 mg and 445 mg respectively. For each pyrotechnic load, the force versus time and the stroke length versus time are measured. The left Y-axis of the graph represents the force [N] and the right Y-axis represents the stroke length [mm]. The X-axis represents the time [ms].

[0071] From this graph it can be seen that the peak force is much lower and the rise time is slower for the 130 mg pyrotechnic load compared to the 445 mg pyrotechnic load.

[0072] Now turn to Figure 7 , shows a graph illustrating different characteristics that can be achieved by a modular actuator according to the present invention. Figure 6 The same actuator used in the previous test, but now with a large gas chamber. In the tests, the actuator was set up with three different gas generators with different pyrotechnic loads: 130 mg, 270 mg and 445 mg. For each load, the force versus time and the stroke length versus time were measured. The left Y-axis shows force [N] and the right Y-axis shows stroke length [mm]. The X-axis shows time [ms].

[0073] From this graph, it can be seen that the peak force is much lower and the lift time is much slower for the 130 mg load than for the 445 mg load. Figure 6 and Figure 7 When comparing the volume of the gas chamber from small to large, it can be seen that by increasing the volume of the gas chamber from small to large, the force will be much lower and it will take longer to reach the peak force. Figure 6 and Figure 7 When looking at the graph of the piston, it can be seen that by increasing the volume of the gas chamber from small to large, it takes much longer to reach the full stroke length of the piston.

[0074] Thus, by varying the volume of the gas chamber and the pyrotechnic load of the gas generator, different characteristics of the actuator can be provided. By using the inventive idea of ​​providing a modular actuator in which different components can be interchanged independently of each other, the characteristics can be fine-tuned to a low cost depending on the intended use of the actuator. This allows not only better performance but also lower costs.

[0075] Although the safety device has been described above in the context of a hood lifter in a vehicle, exactly the same principles apply where the safety device is a seat belt pretensioner or a seat structure reinforcement piston to reinforce the seat structure during high load conditions.

[0076] The invention has been described and illustrated above based on an embodiment where the power connector is arranged adjacent to the second end of the housing. Those skilled in the art will appreciate that the same modular principles apply if the power connector is instead connected at the first end of the housing.

[0077] In this case, the power connector may be configured to connect to the gas generator via an opening in a wall of the housing.

Claims

1. A safety device in a vehicle, the safety device comprising a modular actuator (100), the modular actuator comprising a housing (1) having a first end (2), a piston (4) adapted to be mounted in the housing (1) and configured to move from a retracted position to an extended position, and a gas generator (15), wherein The piston (4) has a first end, which forms a pressure surface (6) facing the first end (2) of the housing (1), A gas chamber (8) is formed between the pressure surface (6) of the piston (4) and the inner wall of the first end (2) of the housing (1), and the gas generator (15) is fluidically connected to the gas chamber (8); and wherein The volume of the gas chamber (8) as seen in the state when the piston (4) is in the retracted position can be selectively adapted by replacing the piston (4) having a first volume with a piston having a second volume, the second volume being different from the first volume; and / or A spacer (25) is arranged in the gas chamber (4).

2. A safety device according to claim 1, wherein the piston (4) comprises an axially extending recess (16) having a mouth facing the first end (2) of the housing (1).

3. The safety device according to claim 1, wherein the gas generator (15) is arranged in the recess (16).

4. A safety device according to claim 3, wherein the spacer (15) is arranged in the recess (16) of the piston (4), and wherein the piston (4) is movable relative to the spacer (25) when the piston (4) moves from the retracted position to the extended position.

5. The safety device according to claim 1, wherein the piston (4) is made of plastic material.

6. The safety device according to claim 1 further comprises a power connector (18) configured to supply power to the gas generator (15), wherein the power connector (18) is connected to a support element (27) of the piston, the support element protruding outside the housing (1).

7. The safety device according to claim 1, further comprising a power connector (18) configured to supply power to the gas generator (15), the power connector (18) being arranged adjacent to the first end (2) of the housing (1).

8. A safety device according to any preceding claim, wherein the housing is formed by deep drawing a metal material.

9. A safety device according to any one of claims 1 to 8, wherein the safety device is a hood lifter in a vehicle.

10. A safety device according to any one of claims 1 to 8, wherein the safety device is a seat belt pretensioner in a vehicle.

11. A safety device according to any one of claims 1 to 8, wherein the safety device is a seat structure reinforcement in a vehicle.

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