PYROTECHNIC SAFETY ELEMENT

Abstract

A pyrotechnic safety element is particularly suited for use in motor vehicles. The safety element includes a conductor, a pyrotechnic unit with a pyrotechnic propellant charge, a severing member for severing the conductor, and a housing. The conductor is composed of two separate conductor parts which are joined at a joining point and are severed by the severing member when the device is triggered.

Claims

1. A pyrotechnic safety element, comprising: a conductor formed of two separate conductor parts being sheet-metal strips arranged along a common axis, said two separate parts adjoining one another in a longitudinal direction and being connected to one another at a connecting point by a formed connection; a pyrotechnic unit with a pyrotechnic propellant charge; a severing member for severing said conductor, said severing member, upon a triggering of the pyrotechnic safety element, moving along the common axis in the longitudinal direction in order to disconnect the two conductor parts from one another at said connecting point; and a housing enclosing said pyrotechnic unit said connecting point and said severing member.

2. The safety element according to claim 1, wherein one end of one said sheet-metal strip lies on one end of the other said sheet-metal strip, forming an overlap between said ends.

3. The safety element according to claim 1, wherein the formed connection is a mechanical forming connection.

4. The safety element according to claim 1, wherein said two conductor parts are connected to one another by a clinching connection.

5. The safety element according to claim 2, wherein said two sheet-metal strips are connected to one another with at least one end of one sheet-metal strip protruding beyond said connecting point, to thereby form a projection on which said severing member engages in the event of triggering.

6. The safety element according to claim 5, wherein said projection is bent up, enabling said severing member to engage under said projection in the event of triggering.

7. The safety element according to claim 1, wherein said two conductor parts are fastened to one another to form an angle therebetween.

8. The safety element according to claim 1, wherein said severing member has a shape of a wedge and, in the event of triggering, said severing member disconnects the connection between said two conductor parts in that said severing member lifts one said conductor part off the other said conductor part.

9. The safety element according to claim 1, wherein said severing member is a plastic material element.

10. The safety element according to claim 1, wherein said housing is formed of precisely two housing parts.

11. The safety element according to claim 10, wherein said two housing parts are a side wall and a housing base, forming a housing shell, a housing cover, and a film hinge connecting said housing shell and said housing cover to one another.

12. The safety element according to claim 9, wherein at least one of said conductor parts is formed with a void in a material thereof for fastening said housing to said at least one conductor part.

13. The safety element according to claim 11, wherein said pyrotechnic unit is led through said side wall and said pyrotechnic unit is encapsulated in plastic for forming said side wall.

14. The safety element according to claim 1 configured as a safety element for a motor vehicle.

15. A fuse box for a motor vehicle, comprising a pyrotechnic safety element according to claim 1.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0041] FIG. 1 is a perspective view of a pyrotechnic safety element with a conductor comprising two conductor parts connected to one another and with a housing;

[0042] FIG. 2 is a perspective view of the two interconnected conductor parts;

[0043] FIG. 3 is a second perspective view showing the two conductor parts connected to one another together with a severing member;

[0044] FIG. 4 is a third perspective view of the two conductor parts connected to one another together with a severing member and a pyrotechnic unit;

[0045] FIG. 5 is a section taken through the housing together with the two conductor parts connected to another; and

[0046] FIG. 6 is a side view showing two conductor parts connected to one another with an alternative design of the connection.

[0047] Parts and elements that correspond to one another are respectively provided with the same designations throughout the figures.

DETAILED DESCRIPTION OF THE INVENTION

[0048] Referring now to the figures of the drawing in detail and first, particularly, to FIGS. 1 and 2 thereof, there is shown an exemplary embodiment of a pyrotechnic safety element 2 in perspective. The safety element 2 has a first conductor part 4 and a second conductor part 6, which are connected to one another at a connecting point 8. The first conductor part 4 is in this case part of a power distribution plate or a bus bar (not included in full in the representation), which is fitted in a so-called fuse box of a motor vehicle. It forms here a connection arm of the distribution plate and consequently serves either as an input current path or as an output current path, which is connected by way of the distribution plate to further connection arms and consequently other current paths of the electrical system of the motor vehicle.

[0049] As shown in FIG. 2 reveals, the two conductor parts 4, 6 designed in the form of strips are arranged along a common connecting axis 10, to be precise in such a way that one end 12 of the second conductor part 6 lies on one end 12 of the first conductor part 4, so that the two ends 12 overlap and are in surface-area contact (i.e., areal contact) in the region of the connecting point 8. For the mechanical connection of the two conductor parts 4, 6 there is a clinching joint 14 formed approximately in the middle of the region of the area of contact, which is produced in the course of a clinching process by means of a cylinder-shaped male die and a female die.

[0050] In the event of triggering, precisely this clinching joint is destroyed with the aid of a severing member 16 represented in FIG. 3, and consequently the mechanical connection between the two conductor parts 4, 6 is once more disconnected. In this case, the severing member 16 positioned on the first conductor part 4 is accelerated by a pyrotechnic propellant charge along the connecting axis 10 in the direction of the connecting point 8. As a result, the severing member 16 slides on the first conductor part 14 in the direction of the end 12 of the second conductor part 6, the severing member 16 being guided by two guiding strips 18, which are integrally formed on the severing member 16 and are positioned on both sides, that is in a flanking manner or straddling manner, on the first conductor part 4.

[0051] In the course of the movement of the severing member 16, the front of the severing member 16, which is in the form of a wedge, reaches the end 12 of the second conductor part 6, which has in the end region a kind of bent lug 20, which points away from the first conductor part 4 and together with the latter forms an angle-like engagement 22 for the wedge-shaped front of the severing member 16. This has the effect that the severing member 16 is reliably driven under the second conductor part 6, and consequently between the two conductor parts 4, 6. As a consequence, the severing member 16 as it were peels the end 12 of the second conductor part 16 off the first conductor part 4, and thereby disconnects the mechanical connection between the two conductor parts 4, 6.

[0052] In this case, the wedge-shaped front of the severing member 16 has a number of geometrical subforms, which differ from one another with regard to their function. For instance, arranged on the sides are two main wedges 24, which disconnect the connection between the two conductor parts 4, 6 and in the course of the movement of the severing member 16 are guided past the clinching joint 14, or rather past the position of the clinching joint 14. Positioned between the two main wedges 24 is a much flatter-formed auxiliary wedge 26, which is arranged downstream of the main wedges 24 (i.e., behind in the functional movement during the severing process) and serves primarily for separating the two conductor parts 4, 6 spatially from one another after the interruption of the connection, and keeping them separated, in particular in the region of the clinching joint 14.

[0053] As already mentioned, the acceleration of the separating member 16 in the event of triggering is caused by a pyrotechnic propellant charge, which is part of a pyrotechnic unit 28 and is ignited by means of a firing signal. In the exemplary embodiments, this firing signal is generated in an airbag control unit of the motor vehicle that is not shown and is fed into the pyrotechnic unit 28 by way of a signal line 30 and plug-in contacts on the pyrotechnic unit 28. Consequently defined as a triggering condition is a traffic accident that leads to the triggering of the airbag system of the motor vehicle controlled by the airbag control unit, and it is precisely in this case that the firing signal that ignites the pyrotechnic propellant charge in the pyrotechnic unit 28 is then also generated.

[0054] As FIG. 1 reveals, the pyrotechnic safety element 2 furthermore comprises a housing 32, which in the end state of assembly is fastened with the aid of four locking notches 34 to the conductor parts 4, 6 connected to one another and encloses the connecting point 8 together with the severing member 16 and the pyrotechnic propellant charge.

[0055] The housing 32 is in this case designed as two parts and consists of a housing base 36, which is depicted in FIG. 5, and also a side wall 38, which is formed by a plastic encapsulation on the pyrotechnic unit 28. In the end state of assembly, that housing wall 38 lies as it were as a sealing ring in a groove on the inner side of the housing base 36, so that as a result the side wall 38 is connected to the housing base 36 in a form-fitting manner.

[0056] The housing base 36 in turn has a housing shell 40 and a housing cover 42, which as subforms of the housing base 36 are connected to one another by way of a film hinge 44. In the course of the final assembly, the housing shell 40 is then slipped or fitted over the conductor parts connected to one another together with the severing member and the pyrotechnic unit 28, at least up to the side wall 38, and subsequently the housing cover 42 is closed and welded on the side opposite from the film hinge 44.

[0057] FIG. 5 shows that the housing 32 forms together with the conductor parts 4, 6 lateral receptacles 46 for the guiding strips 18 of the severing member 16, which in the event of triggering bring about a very precise guidance of the severing member 16 in the manner of a rail guide.

[0058] By contrast, the sealing ring 48 that can be seen in FIG. 3 is not intended to contribute to the guidance of the severing member 16, but primarily to use the increase in pressure generated in the event of triggering by the pyrotechnic propellant charge in the region behind the severing member 16 as completely as possible for the acceleration of the severing member 16, and as far as possible not to allow it to escape unused by way of any openings or gaps.

[0059] FIG. 6 illustrates an alternative design of the connection between the two conductor parts 4, 6 in a schematic view. Here, the conductor parts 4, 6 are bent or angled away in the end region and the severing member 16 is driven perpendicularly in relation to the connecting axis between the two end regions of the two conductor parts 4, 6.

[0060] The invention is not restricted to the exemplary embodiment described above. Rather, other variants of the invention can also be deduced by a person skilled in the art without departing from the subject matter of the invention. In particular, furthermore, all of the individual features described in connection with the exemplary embodiment can also be combined with one another in some other way without departing from the subject matter of the invention.

[0061] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: [0062] 2 pyrotechnic safety element [0063] 4 first conductor part [0064] 6 second conductor part [0065] 8 connecting point [0066] 10 connecting axis [0067] 12 end [0068] 14 clinching joint [0069] 16 severing member [0070] 18 guiding strip [0071] 20 lug [0072] 22 engagement [0073] 24 main wedge [0074] 26 auxiliary wedge [0075] 28 pyrotechnic unit [0076] 30 signal line [0077] 32 housing [0078] 34 locking notch [0079] 36 housing base [0080] 38 side wall [0081] 40 housing shell [0082] 42 housing cover [0083] 44 film hinge [0084] 46 receptacle [0085] 48 sealing ring