Patent Description:
It is well known in the art to use actuators in safety devices in a motor vehicle which actuators are formed by a piston that is moved from a retracted position into an extended position by gas generated by a gas generator. One example is in the use of a hood lifter to lift the hood or bonnet of a vehicle in order of providing protection for a pedestrian hit by the vehicle. It has been observed that if a motor vehicle hit a pedestrian, the bumper of the vehicle will often strike the legs or lower torso of the pedestrian. Hence, the legs of the pedestrian will normally be pushed in the direction of travel of the vehicle and the head and upper torso will normally be tilted towards the hood and windscreen of the vehicle. This tilting movement often causes the head or upper torso of the pedestrian to first make contact with the hood and thereafter, if the impact force from the hit is strong enough and the vehicle continues forward, also reach the windscreen. In order to minimize the damages of the pedestrian caused from such an impact as described above motor vehicles are often provided with so called hood lifting arrangements. These arrangements are generally constructed such that the rear part of the hood, i.e. the part closest to the windscreen, is lifted by one or more actuators. The hood will in general provide an efficient, flexible impact energy absorbing structure in the case when a vehicle hit a pedestrian. However, if the hood is not lifted, there is a higher risk that the hood will be deformed to such extent that hard, non-flexible parts beneath the hood, e.g. an engine block, make contact with the hood and an undesired, stiff impact may be the result from the collision between the pedestrian and the vehicle. In addition, the raising of the rear part of the hood will make the surface of the hood further inclined and contribute to a reduced speed of a body moving towards the windshield. In addition, a less acute angle between the wind shield and the hood will also contribute to a less severe condition for a person being hit by a vehicle.

The hood lifters are arranged in the engine compartment and are configured to act in an upward direction. With prior art designs of the actuators, the gas generator and hence also the power connector is arranged in a bottom end of the actuator, which means that it is hard to access the power connector when connecting the actuator to the vehicles ECU (Electrical Control Unit). One way is to deliver the actuator with an integrated cable harness, i.e. type of extension cord. This allows the interface between the actuator and the cable harness to be delivered in a sealed condition to prevent intrusion of moisture or dirt over time. The cable harness is however the most expensive component in an actuator, whereby there is a desire to omit the cable harness and instead rely on the general cable system already present in the vehicle. The similar problems apply for other safety devices using actuators, such as seat belt pretensioners.

<CIT> discloses a safety device in a vehicle, said safety device comprising an actuator comprising a housing having a first end and a second end, a piston arrangement comprising a piston and a piston rod, the piston arrangement being adapted to fit in the housing and to be moved from a retracted position to an extended position, a gas generator and a power connector configured to power the gas generator; wherein the piston has a first end forming a pressure surface facing the first end of the housing, a gas chamber is formed between the pressure surface of the piston and an inner envelope wall of the housing, and the gas generator is arranged inside the gas chamber.

It is an object of the present invention to provide safety device that is easy to mount in a vehicle and to be connected to the vehicle's ECU also in narrow spaces such as in an engine compartment or under a seat.

Another object is to provide a safety device that allows a more flexible position of the power connector in view of the gas generator to thereby facilitate an adaption to available space in the vehicle.

Yet another object is to provide a safety device where the actuator can be connected to the vehicle's ECU without any integrated cable harness and without jeopardizing the sealing of the actuator.

These and other objects that will be apparent from the following summary and description are achieved by a safety device in a vehicle, said safety device comprising an actuator comprising a housing having a first end and a second end, a piston arrangement comprising a piston and a piston rod having a supporting element projecting outside the housing, the piston arrangement being adapted to fit in the housing and to be moved from a retracted position to an extended position, a gas generator and a power connector configured to power the gas generator; wherein the piston has a first end forming a pressure surface facing the first end of the housing, a gas chamber is formed between the pressure surface of the piston and an inner wall of the housing, and the gas generator being arranged inside the gas chamber; and wherein the power connector is connected to the supporting element, and at least a portion of the power connector and the second end of the piston rod is over-moulded to form an encapsulating sealing.

Accordingly, a safety device is provided wherein the piston arrangement has a supporting element that projects outside the housing and where the power connector is connected to the supporting element. The power connector is configured to power the gas generator which in turn is arranged inside the gas chamber, i.e. inside the housing. This means that a safety device is arranged where the power connector moves along with the piston arrangement as the piston arrangement is set from the retracted position to the extended position. In the event the safety device should be a hood lifter which typically operates in an upward direction, this means that the power connector will be more easy accessible in an engine compartment. Also, the extension and design of the supporting element, and hence the position of the power connector, may be adapted to the available space in the engine compartment, which further facilitates connection of the power connector to the vehicle's ECU no matter if this is made via an integrated cable harness or via the vehicle's cable system.

The supporting element may serve a dual purpose of supporting the power connector and forming an impact surface that is configured to come in contact with the hood in the event the piston arrangement is set to its extended position. In order of not destroying the power connector, it is preferred that the power connector is arranged in an offset position on the supporting element in view of the impact surface. The power connector must accordingly not be arranged aligned with the axial extension of the piston arrangement.

The over-mould may be seen as a plastic cover that provides a protective and sealing encapsulation of interfaces between the parts. This prevents intrusion of moisture and dirt into the interior of the housing.

The gas generator may be arranged in the gas chamber supported by the first end of the piston, and the gas generator may be operatively connected to the power connector via a connecting wire arrangement.

The connecting wire arrangement may be arranged to extend along a channel extending along the interior of the piston arrangement or be arranged to extend along a recess in an outer envelope surface of the piston arrangement.

The connecting wire arrangement may comprise two connecting rods. The connecting wire arrangement may be formed by rigid rods made of a metal with a high conductivity. In an alternative embodiment, the connecting wire arrangement may be formed by flexible or semi-flexible wires. No matter configuration, the connecting wire arrangement interconnect the power connector with terminals of the gas generator.

Each of the two connecting rods may comprise a spring biased connector configured to electrically connect to a respective terminal of the gas generator. A spring biased connector provides an easy mechanical connection during assembly of the actuator. Further, by a spring biased connector, a clamping force may be provided for that acts against the relevant terminal in two opposing radial direction. Thereby a robust mechanical connection is provided for that is strong enough to withstand vibrations and the like during the life length of the vehicle.

The piston rod may comprise at least one axially extending channel or groove configured to receive at least a portion of the connecting rods of the connecting wire arrangement.

The channel or groove contributes to keeping the connecting wire arrangement in position along the piston rod, both during assembly and during moving of the piston arrangement from the retracted position to the extended position.

In the event of the piston arrangement should be made of a plastic material, the plastic will serve as an insulator, whereby there is no need to provide the connecting wire arrangement as such with any insulting cover. Further, in the event of at least one groove, a reduced contact surface may be provided for between the inner wall of the housing and the outer wall or the piston arrangement, which in turn reduces the friction during moving of the actuator from the retracted position to the extended position.

The gas generator may be arranged in the gas chamber supported by the first end of the piston in a position closer to an axial center point of the housing than to the first end of the housing.

The gas generator may in one embodiment be arranged in the bottom of an axially extending recess of the piston. The gas generator may in another embodiment be arranged in the free end of the piston that is facing the closed end wall of the housing. No matter position, the force of the gas that will be generated by the gas generator in the event of a deployment of the gas generator will be directed towards the closed end wall of the housing, and as the gas chamber is filled with gas it will force the piston arrangement in the opposite direction and thereby move the piston arrangement from its retracted position to its extended position. Thus, the direction of the generated gas is opposite to the working direction of the piston arrangement.

The piston arrangement may at least partially be formed by a plastic material, whereby the piston will melt and lose stability in the event of a bonfire situation leading to self-ignition of the gas generator. Thereby, the risk of the piston arrangement forming a projectile that may shoot away in an uncontrolled manner will be reduced.

The piston arrangement may be formed by injection moulding or by 3D printing. By injection moulding or 3D printing, the piston arrangement may be given a complex geometry allowing formation of e.g. one or more recesses that can be used in different ways depending on an expected effect. By way of example, the one or more recesses may be used to fixate the gas generator in the gas chamber in different positions in view of the housing. Thereby it is made possible to adapt the force which is applied by the gas generator to a pressure surface of the piston when deploying the gas generator. One or more recesses may be arranged to provide the gas chamber a given volume as seen in a condition when the piston is in its retracted position. One or more recesses may also be used to fixate one or more spacers to the piston arrangement to thereby provide the gas chamber a given volume as seen in a condition when the piston arrangement is in its retracted position. Furter, one or more recesses may be used to provide the piston with a tailormade contact surface with the inner wall of the housing. Thus, one or more grooves may be formed in the outer envelope surface of the piston arrangement. This makes it possible to better control the friction between the piston and the housing when the piston is moved from the retracted position to the extended position. Additionally, the piston arrangement may be provided with a complex geometry allowing support and/or containment of the connecting wire arrangement and/or the gas generator.

The piston may in one embodiment comprise an axially extending recess forming part of the gas chamber. The recess may in one embodiment have a uniform cross section along its axial extension. The recess may in another embodiment have an axially tapering extension. Since the volume of the recess will form part of the gas chamber of the actuator, the volume of the recess may be adapted to achieve a certain characteristic of the actuator in terms of force and speed.

The actuator may further comprise a spacer arranged in the gas chamber. A spacer allows the provision of a modular actuator where one and the same housing and/or piston arrangement may be used in combination with one or more exchangeable spacers, whereby the volume of the gas chamber may be adapted to achieve a certain characteristic of the actuator in terms of force and speed.

The power connector may be a sealed connector in which an interface between the power connector and terminals of the connecting wire arrangement is filled or sealed-off with a cured sealing material. The sealing material may by way of example be a UV curable adhesive that is injected into the power connector or relevant interfaces during assembly of the actuator. Especially in the event the safety device should be a hood lifter, it is essential that moisture and dirt is not allowed to jeopardize the function of the safety device over time. One way is to seal-off the interface between terminals of the power connector and corresponding terminals of the connecting wire arrangement by filling the same with a curable sealing material.

The housing may be formed by deep drawing a metallic material. Deep drawing allows an easy manufacturing of the housing without any need for welding to form lugs and the like which are normally used to fixate the actuator to the vehicle. Further, since the housing may be formed without welding, there is no risk of introducing welding-related cracks or tensions in the material.

The safety device may in one embodiment be a hood lifter in a vehicle.

The safety device may in one embodiment be a seat belt pretensioner.

The safety device may in one embodiment be a seat structure reinforcer that can be activated during a crash scenario to reinforce the seat structure and connection to the car structure to counteract against high forces to the seat.

The invention will be described in detail with reference to the schematic drawings.

Now turning to <FIG> and <FIG> the overall design of a first embodiment of a safety device according to the invention is disclosed. <FIG> is a schematic exploded view of the safety device and <FIG> is a schematic cross section of the same safety device in an assembled condition.

The safety device comprises an actuator <NUM> that comprises a tubular housing <NUM> having a first end <NUM> and a second end <NUM>. The first end <NUM> comprises a closed end wall <NUM>. The second end <NUM> of the housing <NUM> is an open end through which the components of the actuator <NUM> are inserted during assembly and through which the piston arrangement <NUM> is configured to project during operation of the actuator <NUM> when moved from an ordinary retracted position to an extended position.

The housing <NUM> may be formed by deep drawing a metal material. By deep drawing, the end wall <NUM> of the first end <NUM> of the housing <NUM> will be automatically formed and also, a radially extending flange portion <NUM> may be formed at the second end <NUM> of the housing <NUM>. The flange portion <NUM> may be used to mount the actuator <NUM> to a vehicle.

A free end <NUM> of the piston arrangement <NUM>, configured to face the first end <NUM> of the housing <NUM> comprises a circumferential recess <NUM> configured to receive a sealing <NUM>. The sealing <NUM> is disclosed as an O-ring.

The piston arrangement <NUM> which is formed as a unitary body comprises a first portion forming a piston 5a and a second portion forming a piston rod 5b. The piston 5a and the piston rod 5b are merging with each other via a waist portion 5c forming a radially extending cavity. The piston 5a is configured to face the first end <NUM> of the housing <NUM> whereas the piston rod 5b is configured to face the second end <NUM> of the housing <NUM>. The piston 5a has a first end forming a pressure surface <NUM> facing the first end <NUM> of the housing <NUM>.

The piston 5a comprises an axially extending recess <NUM>, see <FIG>. A gas generator <NUM> is supported by a bottom wall of said recess <NUM> with terminals <NUM> of the gas generator <NUM> extending through openings <NUM> in the bottom wall of the recess <NUM> and into the waist portion 5c. The recess <NUM> is disclosed as having a uniform cross section along its axial extension. The recess <NUM> may with remained function have an axially tapering extension. Since the volume of the recess <NUM> will form part of a gas chamber <NUM> of the actuator <NUM>, the volume of the recess <NUM> may be adapted to achieve a certain characteristic of the actuator <NUM> in terms of applied force and speed.

The gas chamber <NUM> is formed between an inner envelope surface <NUM> of the housing <NUM>, the pressure surface <NUM> of the piston 5a and an inner envelope surface <NUM> of the recess <NUM>. It is to be understood that the volume of the gas chamber <NUM> changes as the piston arrangement <NUM> is moved from its retracted position where the volume is the smallest to its extended position where the volume is the largest.

The gas generator <NUM> is arranged inside the gas chamber <NUM>. The gas generator <NUM> may as is disclosed in <FIG>, be arranged in the gas chamber <NUM> supported by the first end of the piston 5a in a position closer to an axial center point of the housing than to the first end <NUM> of the housing <NUM>.

The piston rod 5b has a supporting element <NUM> configured to extend outside the housing <NUM> in a condition when the piston arrangement <NUM> is in the retracted position in the housing <NUM>.

The supporting element <NUM> of the piston arrangement <NUM> is disclosed as extending transverse to an axial extension of the actuator <NUM>. It is however to be understood that the supporting element <NUM> may have an extension that is adapted to the available space in e.g. an engine compartment in a vehicle or in and around a seat. It may thus form an angle different to <NUM> degrees to the axial extension of the piston.

The supporting element <NUM> supports a power connector <NUM>. The power connector <NUM> is preferably a standard component configured to fit a standard electrical connector of the vehicle. The power connector <NUM> is configured to allow the safety device to be connected to a vehicle's ECU (not illustrated) via a non-disclosed connector or via a non-disclosed cable system. The connector or cable system may be a system forming part of the vehicles power system. The power connector <NUM> is configured to be connected to the terminals <NUM> of the gas generator <NUM> via a connecting wire arrangement <NUM>. The gas generator <NUM> is accordingly arranged in the gas chamber <NUM> supported by the piston <NUM>, and the gas generator <NUM> is operatively connected to the power connector <NUM> via the connecting wire arrangement <NUM>.

The connecting wire arrangement <NUM> comprises in the disclosed embodiment two rods <NUM> which are best seen in <FIG>. Each rod <NUM> has a first connecting portion <NUM> configured to connect to a terminal <NUM> of the gas generator <NUM>, an intermediary portion <NUM> configured to follow the extension of the piston rod 5b and the supporting element <NUM>, and a second connecting portion <NUM> configured to connect to the power connector <NUM> in a position outside the housing <NUM>.

The first connecting portion <NUM>, see <FIG>, is in the disclosed embodiment formed as a U-shaped portion having two opposing plates <NUM> acting as a spring based connector. More precisely, the first connecting portion <NUM> is configured to mechanically connect to a terminal <NUM> of the gas connector <NUM> by the terminal <NUM> being arranged between the two plates <NUM>. As a result of the U-shape, the two plates <NUM> will be forced apart by the terminal <NUM> and thereby clamp against the terminal <NUM> in two opposing radial directions, see arrows. By the thus formed spring biased connector an easy mechanical connection is allowed during assembly of the actuator <NUM>. Thereby a robust mechanical connection is provided for that is strong enough to withstand vibrations and the like during the life length of the vehicle.

The intermediary portion <NUM> of the connecting wire arrangement <NUM> extends along a groove <NUM>, see <FIG>, that is formed in the outer envelope surface of the piston rod 5b. The skilled person realizes that the connecting wire arrangement <NUM> with remained function may be arranged to extend in a channel that extends along the interior of the piston arrangement.

The second connecting portion <NUM>, see <FIG>, extends into a respective opening in the power connector <NUM> thereby forming a terminal <NUM> in the power connector <NUM>.

By the two parallel connecting wire rods <NUM> of the connecting wire arrangement <NUM>, the power connector <NUM> is provided with two terminals <NUM> that can be connected to a vehicle's ECU (not illustrated).

The connecting wire rods <NUM> may be formed as rigid rods made of a metal with a high conductivity. In an alternative embodiment, the connecting wire arrangement <NUM> may be formed by flexible or semi-flexible wires. No matter configuration, the first and second connecting portions <NUM>, <NUM> of the connecting wire arrangement <NUM> interconnect the power connector <NUM> with the terminals <NUM> of the gas generator <NUM>. The channel or groove <NUM> of the piston rod 5b contributes to keeping the connecting wire arrangement <NUM> in position along the piston rod, both during assembly and during moving of the piston arrangement <NUM> from its retracted position to its extended position. In the event the piston arrangement <NUM> should be made of a plastic material, the plastic will serve as an insulator, whereby there is no need to provide the connecting wire arrangement <NUM> as such with any insulting cover.

The piston arrangement <NUM> may at least partially be formed by a plastic material, whereby the piston arrangement will melt and lose stability in the event of a bonfire situation leading to self-ignition of the gas generator <NUM>. Thereby, the risk of the piston arrangement <NUM> forming a projectile that may shoot away in an uncontrolled manner is reduced.

The piston arrangement <NUM> may be formed by injection moulding or by 3D printing. By injection moulding or 3D printing, the piston arrangement <NUM> may be given a complex geometry allowing formation of e.g. one or more recesses <NUM> that can be used in different ways depending on an expected effect. By way of example, the one or more recesses <NUM> may be used to fixate the gas generator in the gas chamber <NUM> in different positions in view of the housing <NUM>. Thereby it is made possible to adapt the force which is applied by the gas generator <NUM> to a pressure surface <NUM> of the piston when deploying the gas generator. One or more recesses <NUM> may be arranged to provide the gas chamber <NUM> a given volume as seen in a condition when the piston is in its retracted position.

Now turning to <FIG> and <FIG> anew. The power connector <NUM> and at least the supporting element <NUM> are disclosed as being over-moulded to form an encapsulating sealing <NUM>. The over-moulding may be seen as a plastic cover that provides a protective and sealing encapsulation of interfaces between the parts. This prevents intrusion of moisture and dirt into the interior of the housing <NUM>.

To further prevent intrusion of moisture and dirt into the housing <NUM>, the second end of the housing <NUM>, which as such is open to allow the piston arrangement <NUM> to be moved to its extended position, is provided with a sealing ring <NUM>.

Now turning to <FIG>, the operation of a safety device according to the first embodiment of the invention is disclosed. <FIG> discloses the safety device with the piston arrangement <NUM> in its retracted position, i.e. its ordinary use. The only part projecting out from the housing is the supporting element <NUM> to which the power connector <NUM> is connected.

The power connector <NUM> is configured to be connected to an Electronic Control Unit, ECU (not illustrated) of a vehicle in a manner well known in the art. In the event the ECU via a crash sensor and processor integrated in the ECU should determine that there is an emergency situation to be responded to, such as a frontal crash, an activation signal is communicated to an ignitor of the gas generator <NUM> which deploys the same. The activation signal is according to the invention transferred from the power connector <NUM> to the gas generator <NUM> via the connecting wire arrangement <NUM> that extends along the piston arrangement <NUM>.

The deployment of the gas generator <NUM> results in a sudden gas generation that acts on the piston arrangement <NUM> and moves the same from the retracted position, see <FIG>, to the extended position, see <FIG>, to thereby e.g. lift a hood or pull the seat belt depending on if the safety device is used as a hood lifter or a seat belt pretensioner.

The force of the gas that is generated upon deployment of the gas generator <NUM> will be directed towards the closed end wall <NUM> of the housing <NUM>, and as the gas chamber <NUM> is filled with gas it will force the piston arrangement <NUM> in the opposite direction and thereby move the piston arrangement <NUM> from its retracted position to its extended position. Thus, the direction of the generated gas is opposite to the working direction of the piston arrangement <NUM>.

Now turning to <FIG> is a highly schematic cross section of an actuator <NUM> according to the invention is disclosed. To facilitate understanding, the piston arrangement <NUM> is disclosed highly schematically. Also the supporting element, the power connector and the connecting wire arrangement have been omitted. The purpose of <FIG> is to disclose that the actuator <NUM> may comprise an optional spacer <NUM>. The spacer is disclosed as being arranged in the gas chamber <NUM>. This allows the provision of a modular actuator where one and the same housing <NUM> and/or piston arrangement <NUM> may be used in combination with one or more exchangeable spacers <NUM>, whereby the volume of the gas chamber <NUM> may be adapted to achieve a certain characteristic of the actuator in terms of force and speed.

In a condition when the gas generator <NUM> is deployed, generated gas will act against the end of the spacer <NUM> facing the second end <NUM> of the housing <NUM>. This will force the piston arrangement <NUM> to move from its retracted position to its extended position by the piston arrangement <NUM> axially moving inside the housing <NUM> and along an outer envelope wall <NUM> of the spacer <NUM>. Accordingly, there is a relative movement between the spacer <NUM> and the piston arrangement <NUM>.

Now turning to <FIG>, an exploded view of a second embodiment of the safety device according to the invention is disclosed. One difference between the second embodiment and the first embodiment is the design of the connecting wire arrangement <NUM>' and the position of the power connector <NUM>. The power connector <NUM> is connected to the supporting element <NUM> of the piston arrangement <NUM> and hence to the piston arrangement <NUM> via a cable harness <NUM>. The cable harness <NUM> encloses two wires <NUM> that constitute the connecting wire arrangement <NUM>'. The wires <NUM> extend from the power connector <NUM> that is arranged outside the housing <NUM> to the gas generator <NUM> that is arranged in the housing <NUM>. The first ends of the wires <NUM> connects to the terminals <NUM> of the gas generator <NUM>. The connection may by way of example be a mechanical or soldered connection. The second ends of the wires <NUM> connect to the power connector <NUM>. The wires may be flexible, semi flexible or even rigid.

Now turning to <FIG>, a schematic cross section of a safety device according to a third embodiment is disclosed. The embodiment differs from that of the first embodiment in that the housing <NUM> in its first end <NUM> comprises a first eyelet <NUM>. The first eyelet <NUM> is configured to form a first connection point when arranging the safety device in a vehicle. Further, the embodiment differs from that of the first embodiment in that the support element <NUM> comprises a second eyelet <NUM>. The second eyelet <NUM> is configured to form a second connection point when arranging the safety device in a vehicle. The first and second eyelets <NUM>, <NUM> may be used to allow a pivotable suspension of the safety device.

Accordingly and in summary, a safety device is provided wherein the piston arrangement <NUM> has a supporting element <NUM> that projects outside the housing <NUM> and where the power connector <NUM> is connected to the supporting element <NUM>. The power connector <NUM> is configured to power the gas generator <NUM> which in turn is arranged inside the gas chamber <NUM>, i.e. inside the housing <NUM>. This means, that the power connector <NUM> moves along with the piston arrangement <NUM> as it is set from the retracted position to the extended position. In the event the safety device should be a hood lifter which typically operates in an upward direction, this means that the power connector <NUM> will be more easy accessible in an engine compartment. Also, the extension and design of the supporting element <NUM>, and hence the position of the power connector <NUM>, may be adapted to the available space in the engine compartment, which further facilitates connection of the power connector <NUM> to the vehicle's ECU no matter if this is made via an integrated cable harness or via the vehicle's cable system.

The supporting element <NUM> may serve a dual purpose of supporting the power connector <NUM> and forming an impact surface <NUM> that is configured to either come in contact with or remain in contact with the hood in the event the piston arrangement is set to its extended position. In order of not destroying the power connector <NUM>, it is preferred that the power connector <NUM> is arranged in an offset position on the supporting element <NUM> in view of the impact surface <NUM>. The power connector <NUM> must accordingly not be arranged aligned with the axial extension of the piston arrangement <NUM> but may form any suitable angle thereto. Further, the power connector <NUM> must not be arranged to project from the supporting element <NUM> on the same side as the intended impact surface <NUM>. The embodiment of <FIG> discloses one example where the power connector <NUM> is arranged on a surface of the supporting element <NUM> opposite the impact surface <NUM>.

The power connector <NUM> has been disclosed as a female type connector. It may with remained function be a male type connector. Depending on the connector system used in the vehicle to which the actuator <NUM> should be connected, the power connector <NUM> can be an adaptor configured to receive another power connector (not disclosed) which in turn comprises terminals to connect with the terminals of the connecting wire arrangements <NUM> that extends from the gas generator <NUM> inside the housing <NUM>.

Claim 1:
A safety device in a vehicle, said safety device comprising an actuator (<NUM>) comprising a housing (<NUM>) having a first end (<NUM>) and a second end (<NUM>), a piston arrangement (<NUM>) comprising a piston (5a) and a piston rod (5b) having a supporting element (<NUM>) projecting outside the housing (<NUM>), the piston arrangement (<NUM>) being adapted to fit in the housing (<NUM>) and to be moved from a retracted position to an extended position, a gas generator (<NUM>) and a power connector (<NUM>) configured to power the gas generator (<NUM>); wherein
the piston (<NUM>) has a first end forming a pressure surface (<NUM>) facing the first end (<NUM>) of the housing (<NUM>),
a gas chamber (<NUM>) is formed between the pressure surface (<NUM>) of the piston (<NUM>) and an inner envelope wall (<NUM>) of the housing (<NUM>), and the gas generator (<NUM>) is arranged inside the gas chamber (<NUM>); and wherein
the power connector (<NUM>) is connected to the supporting element (<NUM>) and at least a portion of the power connector (<NUM>) and the second end of the piston rod (5b) is over-moulded to form an encapsulating sealing.