EP3251141B1 - Pyrotechnic safety element - Google Patents

Description

The invention relates to a pyrotechnic securing element, in particular for the motor vehicle sector, comprising a conductor, a pyrotechnic unit with a pyrotechnic propellant charge, a separating body for cutting through the conductor and a housing.

To protect current paths of a vehicle electrical system of a motor vehicle, so-called fuses are typically integrated into the current paths, which melt or melt when an overcurrent occurs and thereby disconnect the corresponding current path or the corresponding current paths from the energy supply.

In addition, so-called pyrotechnic fuse elements are used in the automotive field, which do not serve to avoid overcurrents, but by an ignition signal, ie an active control, triggered when a predetermined condition, the so-called trigger condition is met. Thus, a pyrotechnic safety element, also known as a pyrotechnic safety switch, pyrotechnic switch or pyrotechnic separator, is a type of emergency stop switch of stop category 0 (EN ISO 13850: 2008 pt. 4.1.4 and EN 60204-1: 2006 clause 9.2 .2), which can be triggered manually in principle and / or automatically controlled under the predetermined trigger condition and thereby triggered.

A corresponding pyrotechnic fuse element is constructed according to a known principle and includes a pyrotechnic propellant, which is connected by an electrical ignition signal, for example, a sensor signal of a connected Sensor is ignited and as a result a separator body, means a wedge or a bolt accelerated, so that this mechanically cuts an electrical conductor.

In the automotive sector, corresponding pyrotechnic security elements are usually used as a so-called battery disconnect switch which disconnects the battery or the accumulator of the motor vehicle from the rest of the electrical system of the motor vehicle in the event of a traffic accident and thus virtually isolated. This prevents that accidentally exposed and / or damaged electrical cable connections or exposed and / or damaged electronic components pose a risk, especially for rescue workers, so for example. Ignite leaking oil or gasoline.

EP-A-1710871 discloses a fuse element according to the preamble of claim 1.

Proceeding from this, the object of the invention is to provide an advantageously designed pyrotechnic securing element.

This object is achieved by a pyrotechnic fuse element with the features of claim 1. Preferred developments are contained in the dependent claims.

A corresponding pyrotechnic securing element is designed in particular for the motor vehicle sector and comprises a conductor, a pyrotechnic unit, a separating body and a housing. Here, the conductor is formed by two separate conductor sections, which are connected to one another at a connection point and are separated again in the case of release by the separating body at the connection point.

So instead of positioning as usual a pyrotechnic unit with a separator on a solid, one-piece and one-piece ladder and sever this by means of the separator in the event of triggering, is disconnected or broken in a pyrotechnic fuse element presented here in the event of triggering a connection between two conductor sections, the previously produced under specified conditions.

Here, the connection is designed such that the forces to be applied for a separation are significantly lower than the forces which are to be applied in order to cut through a solid conductor. As a result, it is then possible to use a simpler and more compact pyrotechnic unit in the pyrotechnic fuse element and, accordingly, a pyrotechnic fuse element preferably has a pyrotechnic unit that converts a reduced amount of energy when triggered.

Although in principle the force to be applied for a separation can also be reduced by introducing material recesses into a solid conductor, for example by drilling or milling, as part of a reworking, however, such a reworking is relatively complicated, and also in comparison with the solution presented here expensive.

According to a preferred embodiment variant, each conductor section is further formed by a conductor strip or sheet metal strip and, for example, made of copper, for example CU-ETP, a copper alloy, aluminum or an aluminum alloy.

The connection of the two conductor sections is preferably application-dependent, ie. also in dependence of the material used for the conductor sections, wherein the connection is in any case designed such that the forces to be applied for the separation are specified as accurately and appropriately as possible. In addition, the connection is designed such that it is ensured that after triggering of the pyrotechnic securing element not only the connection between the two conductor sections is broken, but the two conductor sections are also sufficiently far apart spatially separated, so that neither due to contact nor as a result Rollover current flows over the two conductor sections.

In this case, the two conductor sections are preferably formed as sheet metal strips, wherein the ends rest on each other, so that they overlap and in the Touch the end area or overlap area flat. In this way it is ensured that the contact resistance between the two conductor sections is relatively small, as long as the connection between the two conductor sections is intact.

In order to keep the production cost of the pyrotechnic fuse element as simple as possible, it is also advantageous to connect the two conductor sections by deformation or deformation with each other. It is therefore preferably a purely mechanical and / or positive connection between the two conductor sections formed and on a fluid connection, for example, by gluing or welding is preferably omitted.

In an advantageous embodiment, the connection of the two conductor sections by means of clinching, also called clinching, this being suitably used as sheet metal strip conductor sections are used. These are then advantageously arranged for the process of clinching, such that one end of one conductor strip rests on one end of the other conductor strip so that the respective ends overlap, and it is precisely in this region in which the two ends overlap that occurs Connection of the two conductor strips by clinching.

For this purpose, the two correspondingly arranged conductor sections are typically arranged between a so-called die and a die, and the connection between the conductor sections is then produced by moving the die and the die toward one another. In this case, the stamp is, for example, cylindrically shaped and the die has a cylindrical recess with dimensions enlarged relative to the punch, so that the cylindrical shape of the punch can be driven at least partially into the cylindrical recess of the die during clinching and between the cylindrical shape of the punch and the cylindrical Deepening of the die still enough space for material of the two conductor sections is given.

It is also advantageous if the metal strips or conductor strips have a sheet thickness or plate thickness between 0.4 mm and 1.2 mm and when the conductor cross section is greater than 10 mm ² .

Furthermore, it is advantageous to constructively specify an attack for the separating body, by which the desired movement of the separating body is supported in the event of triggering, inter alia, since this increases the reliability of the pyrotechnic securing element. Thus, if the separating body has, for example, a wedge shape, it is advantageous to specify a kind of notch or an angular shape open to the separating body as an attack, so that the wedge-shaped separating body is driven into the notch or the angle shape in the event of triggering and thereby into a specifically predetermined movement is forced.

Now, if the two conductor sections are formed as sheet metal strips, which rest on each other in the region of the junction, it is expedient to specify for the separator in the event of triggering a movement such that it is driven between the two superimposed conductor sections and thereby separates the two conductor sections spatially from each other , For this purpose, it is advantageous if that end of the conductor section to which the separating body moves in the event of a trigger, bent away from the other conductor section, so to speak, is bent, so that the separator forced in the case of release under the weg- or bent end of the corresponding conductor section and driven between the two conductor sections. If the separating body is wedge-shaped in this case, the connection between the two conductor sections is separated in the case of release, in that the separating body lifts or shears off a conductor section from the other conductor section.

In an advantageous development, two strip-shaped conductor sections are then aligned along a common axis and arranged so that they adjoin one another in a longitudinal direction. Along this common axis, the separating body moves in the case of release in the longitudinal direction to separate the two conductor sections from each other. Preferably, one end of the one conductor strip lies on one end of the other conductor strip on, so that the two ends overlap partially and lie flat on each other.

On one of the two strip-shaped conductor sections then in particular a wedge-shaped separating body is positioned, which in case of release, for example, slidably along the corresponding conductor section in the direction of the connection point, ie in the direction of the area in which the two ends of the two conductor sections rest on one another, moves or rather, it is driven in the appropriate direction. Here is on the same side of a conductor section on which rests the separator body, the other conductor section in the region of the junction on which the wedge-shaped separating body facing end piece is bent away from the other conductor section, so that this tail together with the other conductor section an angular attack for forms the wedge-shaped separating body, in which the wedge-shaped separating body is driven in the event of triggering, whereby the separating body between the two conductor sections is forced and thereby solves them safely from each other and spatially separated from each other.

For reliable guidance of the separating body, it is preferably mounted in a slidable manner with a guide element on the one conductor section. The guide element is designed in particular as a guide strip arranged, for example, laterally on the conductor section, or comprises at least one such guide rail.

Alternatively, the two conductor sections are secured together so that they form an angular shape and are accordingly not arranged along a common axis. In addition, it is expedient to adapt the direction of movement or path of the separating body in the triggering case relative to the orientations of the two conductor sections to the respective application and / or the respective space requirement.

Since the separating body is exposed as a result of the configuration of a pyrotechnic securing element presented here in the triggering case relatively low loads, can be in a pyrotechnic fuse element presented here also use a separator made of plastic and in favor of the simplest possible production as well as cost reasons, a separating body made of plastic, for example of polyoxymethylene (POM) is preferably used.

Also, the housing is preferably made of a plastic, in which case, for example, polyamide (PA) or polybutylene terephthalate (PBT) is used. In addition, the housing is advantageously kept simple, in particular, to keep the final assembly, so the composition of the prefabricated items to the pyrotechnic fuse element, simple. Preferably, the housing is constructed of exactly two housing parts, namely a side wall and a housing base, in which a housing shell and a housing cover are connected to one another via a hinge, in particular a film hinge.

Those housing base, which typically surrounds most of the remaining components of the pyrotechnic securing element in the final assembled state, is more preferably closed during the final assembly and in particular hermetically sealed, for example by welding the housing shell and the housing cover together, for example on the side opposite the film hinge. This ensures that the generated in the case of release by means of the pyrotechnic propellant charge of the pyrotechnic fuse element pressure can be used substantially completely to accelerate the separator and can not escape the quasi unused out of the case.

For fixing the housing or for mechanical attachment of the housing to the interconnected conductor sections, a holding element is preferably formed on at least one conductor section, which is designed for example as a material recess, on which the housing is locked in the final assembled state by positive locking.

In particular, in the case of strip-shaped conductor sections, it is advantageous to design the holding element such that in each sheet metal strip, ie in each conductor section two opposing lateral indentations are given, so that the junction of the two conductor sections is quasi framed by four material recesses or notches.

Since the final assembly, as already mentioned, should be kept as simple as possible and in addition to the conductor sections also a signal line through the housing is led to the outside, via which an ignition signal in the case of triggering the pyrotechnic propellant charge of the pyrotechnic unit is transmitted, is according to a further advantageous Embodiment of the pyrotechnic fuse element, the pyrotechnic unit, molded with plastic, and in particular such that just this Kunststoffumspritzung forms the side wall of the housing. The plastic extrusion coating is, for example, annular and, in the final assembled state, preferably connected by positive engagement with the housing base or fastened to the housing base. In the simplest case, this is formed on the housing base of a groove which is positioned with closed housing base on the housing base inside and is preferably configured as a circumferential groove.

Since relatively small forces for the separation of the two conductor sections are to be applied by the pyrotechnic unit due to the configuration of the pyrotechnic security element presented here, the pyrotechnic propellant charge of the pyrotechnic unit is preferably adapted to the reduced requirements and accordingly made smaller and weaker. In particular, this makes it possible to realize a total of a relatively compact pyrotechnic securing element and also for this reason, a pyrotechnic securing element presented here is also used and installed in so-called fuse boxes.

Corresponding pyrotechnic security elements are thus not only intended to isolate the installed batteries or accumulators in a motor vehicle when triggered, ie in particular in the case of a traffic accident, and from disconnect other electrical system, but also to isolate individual modules or electrical systems in the case of triggering within the rest of the electrical system, which is particularly advantageous if, for example, energy buffers are integrated into the electrical system, so for example, capacitors, could be triggered by their discharge also accident consequential.

FIG 1

in einer perspektivischen Ansicht ein pyrotechnisches Sicherungselement mit einem Leiter aus zwei miteinander verbundenen Leiterteilstücken und mit einem Gehäuse,

FIG 2

in einer perspektivischen Ansicht die zwei miteinander verbundenen Leiterteilstücke,

FIG 3

in einer zweiten perspektivischen Ansicht die zwei miteinander verbundenen Leiterteilstücke zusammen mit einem Trennkörper,

FIG 4

in einer dritten perspektivischen Ansicht die zwei miteinander verbundenen Leiterteilstücke zusammen mit einem Trennkörper und einer pyrotechnischen Einheit,

FIG 5

in einer Schnittdarstellung das Gehäuse zusammen mit den zwei miteinander verbundenen Leiterteilstücken sowie

FIG 6

in einer Seitenansicht zwei miteinander verbundenen Leiterteilstücke mit einer alternativen Verbindungsgestaltung.

Embodiments of the invention will be explained in more detail with reference to a schematic drawing. Show:

FIG. 1

in a perspective view of a pyrotechnic fuse element with a conductor of two interconnected conductor sections and with a housing,

FIG. 2

in a perspective view, the two interconnected conductor sections,

FIG. 3

in a second perspective view, the two interconnected conductor sections together with a separating body,

FIG. 4

in a third perspective view of the two interconnected conductor sections together with a separating body and a pyrotechnic unit,

FIG. 5

in a sectional view of the housing together with the two interconnected conductor sections as well

FIG. 6

in a side view, two interconnected conductor sections with an alternative connection design.

Corresponding parts are provided in all figures with the same reference numerals.

An example described below and in Fig. 1 shown in a perspective view pyrotechnic fuse element 2 has a first conductor section 4 and a second conductor section 6, which are connected to one another at a junction 8. The first conductor section 4 is part of a not fully illustrated with power distribution plate or a bus bar, which is or which is installed in a so-called fuse box of a motor vehicle. In this case, it forms a connecting arm of the distributor plate and thus serves either as an input current path or as an output current path, which is connected via the distributor plate to other connection arms and thus to other current paths of the electrical system of the motor vehicle.

How out Fig. 2 shows, the two strip-shaped conductor sections 4,6 are arranged along a common connecting axis 10, in such a way that one end 12 of the second conductor section 6 rests on one end 12 of the first conductor section 4, so that the two ends 12 overlap and in Touch surface of joint 8 flat. Approximately in the middle of the contact surface, a clinching 14 is formed for the mechanical connection of the two conductor sections 4,6, which is produced in the context of a clinching process by means of a cylindrical punch and a die.

In the case of triggering, exactly this assertion is done with the help of an in Fig. 3 shown separating body 16 destroyed and thus the mechanical connection between the two conductor sections 4,6 dissolved again. In this case, the positioned on the first conductor section 4 separating body 16 is accelerated by means of a pyrotechnic propellant along the connecting axis 10 in the direction of junction 8 and as a result slides the separator 16 on the first conductor section 4 in the direction of the end 12 of the second conductor section 6, wherein the separator body 16 through two guide power 18 is guided, which are integrally formed on the separating body 16 and on both sides, so flanking, are positioned on the first conductor section 4.

In the course of the movement of the separating body 16, the wedge-shaped front of the separating body 16 reaches the end 12 of the second conductor section 6, which has a kind of bent tab 20 in the end region facing away from the first conductor section 4 and together with this an angular attack 22 for wedge-shaped front of the separator 16 forms. As a result, the separating body 16 is securely driven under the second conductor section 6 and thus between the two conductor sections 4,6. As a result, the separating body 16 peels off the end 12 of the second conductor section 6, as it were, from the first conductor section 4 and thus eliminates the mechanical connection between the two conductor sections 4, 6.

In this case, the wedge-shaped front of the separating body 16 has a plurality of geometric partial shapes, which differ from each other in terms of their function. Thus, two main wedges 24 are arranged on the sides, which break the connection between the two conductor sections 4, 6 and are guided past the penetration joint 14 or rather at the position of the clinching joint 14 in the course of the movement of the separation body 16. Between the two main wedges 24 a substantially flatter designed auxiliary wedge 26 is positioned downstream of the main wedges 24 and serves primarily to separate the two conductor sections 4,6 after dissolving the compound, in particular in the region of the clinching 14 spatially separated and separated to keep.

The acceleration of the separating body 16 in the case of triggering, as already mentioned, caused by a pyrotechnic propellant charge, which is part of a pyrotechnic unit 28 and is ignited by means of an ignition signal. In the exemplary embodiment, this ignition signal is generated in an airbag control unit of the motor vehicle, not shown, and fed via a signal line 30 and plug contacts to the pyrotechnic unit 28 in the pyrotechnic unit 28. As a trigger condition thus a traffic accident is set, which leads to the triggering of the airbag control unit controlled airbag system of the motor vehicle and it is precisely in this case, the ignition signal is generated, which ignites the pyrotechnic propellant charge in the pyrotechnic unit 28.

How out Fig. 1 shows the pyrotechnic fuse element 2 further comprises a housing 32 which is fixed in the final assembled state by means of four notches 34 on the interconnected conductor sections 4,6 and includes the connection point 8 together with the separating body 16 and the pyrotechnic propellant charge.

The housing 32 is designed in two parts and consists of a housing base 36, which in Fig. 5 is shown, and a side wall 38 which is formed by a plastic extrusion on the pyrotechnic unit 28. In the final assembled state that housing wall 38 is quasi as a sealing ring in a groove on the inside of the housing base 36, so that in this way the side wall 38 is positively connected to the housing base 36.

The housing base 36 in turn has a housing shell 40 and a housing cover 42, which are connected to each other as part shapes of the housing base 36 via a film hinge 44. As part of the final assembly, the housing shell 40 is then placed over the interconnected conductor sections together with the separator and the pyrotechnic unit 28, at least up to the side wall 38, and then the housing cover 42 is closed and welded on the film hinge 44 opposite side.

In Fig. 5 It can be seen that the housing 32 forms together with the conductor sections 4,6 lateral receptacles 46 for the guide rails 18 of the separating body 16, which in the case of triggering a very precise guidance of the separating body 16 in the manner of a rail guide condition.

The in Fig. 3 recognizable sealing ring 48, however, is not intended to contribute to the leadership of the separator 16, but primarily to use the triggering case generated by the pyrotechnic propellant charge increase in the area behind the separator 16 as completely as possible to accelerate the separator 16 and preferably not about any Let openings or gaps escape unused.

In Fig. 6 is still an alternative embodiment of the connection between the two conductor sections 4,6 shown schematically. Here, the conductor sections 4,6 are bent or angled in the end region and the separating body 16 is driven perpendicular to the connecting axis between the two end regions of the two conductor sections 4,6.

The invention is not limited to the embodiment described above. Rather, other variants of the invention can be derived therefrom by the person skilled in the art without departing from the subject matter of the invention.

LIST OF REFERENCE NUMBERS

2

Pyrotechnic fuse element

4

first ladder section

6

second conductor section

8th

junction

10

connecting axis

12

The End

14

Clinching

16

separating body

18

guide rail

20

flap

22

attack

24

main wedge

26

auxiliary wedge

28

pyrotechnic unit

30

signal line

32

casing

34

notch

36

housing base

38

Side wall

40

shell

42

housing cover

44

film hinge

46

admission

48

seal

Claims (12)

1. Pyrotechnic safety element (2), in particular for use in motor vehicles, comprising a conductor (4, 6), a pyrotechnic unit (28) with a pyrotechnic propellant charge, a severing member (16) for severing the conductor (4, 6) and a housing (32),
   wherein the conductor (4, 6) is formed by two separate conductor subpieces (4, 6), which are designed as sheet-metal strips (6), are connected to one another at a connecting point (8) by a forming process and in the event of triggering are disconnected again at the connecting point (8) by the severing member (16), characterized in that the conductor pieces are arranged along a common axis, so that they adjoin one another in a longitudinal direction, the severing member (16) moving along this common axis (10) in the longitudinal direction in the event of triggering in order to disconnect the two conductor subpieces (4, 6) from one another.
2. Safety element (2) according to Claim 1,
   characterized
   in that one end (12) of one sheet-metal strip (6) lies on one end (12) of the other sheet-metal strip (4), so that the two ends (12) overlap.
3. Safety element (2) according to either of Claims 1 and 2,
   characterized
   in that the two conductor subpieces (4, 6) are connected to one another by clinching (14).
4. Safety element (2) according to either of Claims 2 and 3,
   characterized
   in that the two sheet-metal strips (4, 6) are connected to one another in such a way that at least one end (12) of one sheet-metal strip (6) protrudes beyond the connecting point (8), and thereby forms a projection (20) on which the severing member (16) engages in the event of triggering.
5. Safety element (2) according to Claim 4,
   characterized
   in that the projection (20) is bent up, so that the severing member (16) engages under the projection (12) in the event of triggering.
6. Safety element (2) according to one of Claims 1 to 5,
   characterized
   in that the two conductor subpieces (4, 6) are fastened to one another in such a way that they together form the form of an angle.
7. Safety element (2) according to one of Claims 1 to 6,
   characterized
   in that the severing member (16) is designed in the form of a wedge and in the event of triggering disconnects the connection between the two conductor subpieces (4, 6) by said severing member lifting the one conductor subpiece (6) off the other conductor subpiece (4).
8. Safety element (2) according to one of Claims 1 to 7,
   characterized
   in that the severing member (16) is produced from a plastic.
9. Safety element (2) according to one of Claims 1 to 8,
   characterized
   in that the housing (32) has precisely two housing parts (36, 38), to be specific a side wall (38) and a housing base (36), in the case of which a housing shell (40) and a housing cover (42) are connected to one another in particular by way of a film hinge (44).
10. Safety element according to one of Claims 1 to 9,
    characterized
    in that, for fastening the housing (32), at least one clearance in the material (34) is formed on at least one conductor subpiece (4, 6).
11. Safety element according to Claim 9 or 10,
    characterized
    in that the pyrotechnic unit (28) is led through the side wall (38), the pyrotechnic unit (28) being encapsulated in plastic for the forming of the side wall (38).
12. Fuse box for a motor vehicle with a pyrotechnic safety element (2) according to one of the preceding claims.

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