EP3618090B1 - Pyrotechnic current disconnector - Google Patents

Description

Technical area

The present invention relates to a pyrotechnic current isolator in which a conductor is severed by the application of pressure, the current isolator having a housing which has a lower part and an upper part with an igniter, the lower part and upper part being connected to one another by screws and the conductor between the lower part and Upper part is inserted and has holes through which extend elements that fix the conductor in the longitudinal direction.

State of the art

The increase in traffic and the associated pollutant emissions from vehicles are now a major problem, especially in inner-city areas. Electric (BEV) and hybrid vehicles are currently seen as a possible solution, with the latter being predicted to increase. The advantage of hybrid vehicles is that a motor / generator element is used for the frequent starting and braking processes, which has a high degree of efficiency when starting and which feeds the energy back into the power storage unit when braking. This energy storage device, which is small compared to a fully electric vehicle, still has a very high short-circuit current, which must be reliably switched off in the event of damage.

Current isolators for automotive applications have been known for a long time, typical versions are the PSS1 and PSS2 from Autoliv, whose basic structure is shown in the DE 102004023415 A is described. Due to the construction by means of multiply angled conductors, however, these can only be produced with considerable financial outlay and have only limited protection against water.

Another design is in the WO 2012/025272 A the company Autokabel described, here the manufacture of the conductor by soldering the two conductor sections is a main cost driver. Here the separation is not carried out by a separating piston, but by a liquid / pasty separating and extinguishing agent. The mandatory filling with liquid / pasty separating and extinguishing agent is only required for certain requirements.

Finally there are the concepts of the Safran company, WO 2016/038044 A , the principle of which is an equally complex, multi-stage separation of the conductor, the manufacture of the conductor is also complex and the system is not watertight. Here the housing consists of an upper part and a lower part, the upper part and the lower part are held together by four screws at the four corners.

A device of the type mentioned is from WO 2017/066816 A known. Here, too, the housing is held together by screws, with nuts being provided as counterparts to the screws. The conductor is fixed in the housing by pins.

Brief description of the invention

It is the object of the present invention to simplify the construction of this circuit breaker and thereby to reduce the manufacturing costs.

According to the invention, this object is achieved by a circuit breaker of the type mentioned at the outset in that the elements that fix the conductor in the longitudinal direction are formed by the screws that connect the lower part and the upper part to one another.

According to the invention, the screws fulfill a double function: they not only hold the upper part and lower part together, but also fix the conductors in the housing. This not only saves components, but also simplifies assembly.

Preferably the screws are insulated from the conductor. This prevents the separation point from being bridged by connecting the screws after the conductor has been separated. This insulation can be done by a sleeve, which can also be molded onto the upper part or lower part.

In a preferred embodiment, the current isolator has a separating piston which, when the conductor is separated, punches a circuit board out of the conductor, so that two conductor sections separated from one another remain, with a collecting chamber for the plate and the separating piston being provided on the side of the conductor remote from the fuse, as is the case with the generic WO 2017/066816 A the case is.

If the collecting chamber tapers away from the conductor, so that a bending moment arises when the plate and separating piston are braked, this is absorbed by the screws. So the screws stiffen the housing.

As an alternative to this, the separating piston can be braked in that it is embodied in a stepped manner, so that the separating piston hits the ladder sections with the step. Since the ladder sections are fixed by the screws, the force required for braking is transmitted to the screws and absorbed by them.

If the step is inclined, there is also a force on the ladder sections in their longitudinal direction, which is absorbed directly by the screws as a transverse force, so that the tension on the screws is reduced.

In the case of the stepped separating piston, in particular, it is advantageous if the heads of the screws rest on the lower part and thereby reinforce the housing in the area where the separating piston and plate meet.

The conductor is preferably sealed off from the housing by a seal against the ingress of water. When the seal is sprayed onto the conductor, no additional components are necessary.

The screws preferably have a safeguard against automatic loosening. This can be done in a known manner by means of an adhesive.

Furthermore, the screws can be secured against deliberate loosening. This can be done by means of a screw contour that is destroyed when a dedicated tightening torque is reached, e.g. by means of a multi-part screw head, of which at least a part breaks off when a dedicated tightening torque is reached. However, it can also be done by means of a screw contour that only allows the application of force in one direction, e.g. the directional application of force can take place over at least one surface with a wedge-shaped cross-section.

The screws are preferably made directly into the plastic existing lower part or upper part and have a thread optimized for adhesion in plastic. In this way you can not only save the nuts and thus simplify assembly, the housing is also better stabilized due to the direct connection of screw and upper or lower part. The screws preferably have a pull-out force of at least 500 N.

Brief description of the drawing figures

The present invention is explained in more detail with the aid of the accompanying drawings. It shows: Fig. 1 a current isolator according to the invention in section, Fig. 2 a variant of this with a different braking of the separating piston, Fig. 3 a circuit breaker with an integrated signal line, which is also disconnected when the pyrotechnic switch is triggered, in a section that compares to Figs. 1 and 2 is guided rotated by 90 °, and Fig. 4 the isolating piston of the isolator from Fig. 3 in perspective view.

Description of the types of execution

According to Fig. 1 a circuit breaker 1 according to the invention has a conductor 2 with conductor sections 3a, 3b, the conductor 2 being able to be fixed in the housing through holes 4a, 4b. The housing consists of an upper part 5 and a lower part 6. In the upper part 5 there is an igniter 7 and a separating piston 8 with a groove 9 which contains an O-ring 10. The conductor 2 has two predetermined breaking points 11a, 11b in the interior of the housing, which delimit a central section 12. If this section 12 is separated from the conductor 2, it is also called a circuit board. As far as the design corresponds to the existing concepts.

In order to prevent the cut-off circuit board from coming into contact again, it is necessary for the circuit board to be held in place in the lower part 6 by structural elements after the circuit breaker 1 has been triggered. These structural elements can, for example, have a knob-like design.

The separating piston 8 preferably has a concave cutting surface which enables the conductor 2 to be separated cleanly.

Furthermore, a clean separation process is made possible by the fact that the conductor 2 has a greater width outside the housing than on the Has separation points.

The upper part 5 and the lower part 6 are held together by screws 13a, 13b, which lead through the conductor 2 and thus not only fix the conductor 2 and hold the housing halves together, but also reinforce them. This means that additional metallic reinforcements are not required. In the holes 4a, 4b through the conductor sections 3a, 3b, insulation 14a, 14b can prevent contact between the screws 13a, 13b and the conductor sections 3a, 3b. This insulation can be part of the upper or lower part 5 or 6 or a separate part.

The screws 13a, 13b are particularly preferably inserted from the side remote from the igniter, as a result of which the heads 15a, 15b of the screws 13a, 13b become a structural reinforcement of the lower part 6. As a result, the blank 12 punched out by the separating piston 8 during the separating process can be safely caught.

The collecting chamber 16 for the plate 12 is conical, so that when the plate 12 (and possibly the separating piston 8) is braked, a bending moment is generated on the screws 13a, 13b and these serve as structural reinforcement. This bending moment presses the screws against the plastic in the transverse direction, which increases their axial holding force. In this design, the screws 13a, 13b can also be inserted from the igniter side.

As screws, screws with plastic threads are preferred. Compared to metric screws, these are characterized by a large pitch, significantly more material between the threads and a largely axial load on the carrier material. Particularly preferred are screws with pull-out forces of at least 500 N. The screws can be equipped with a safeguard against automatic loosening (for example in the event of vibration), for example by means of serrations or ribs on the screw head.

The screws can have a contour on the head for transmitting the screwing and tightening torque, which becomes ineffective when a defined torque is reached, for example by tearing off part of the Head. This effectively prevents disassembly.

To achieve watertightness, especially after the shot, a seal 17 is provided; this is particularly preferably sprayed onto the conductor 2 and consists of conventional sealing materials, for example EPDM or TPE with approx. 70 Shore; here, too, the fixation of the conductor sections 3a helps , 3b during and after the separation process by the screws 13a, 13b to ensure the tightness.

In Fig. 2 Another design is shown in which the separating piston 8 is designed as a stepped piston and the position of the predetermined breaking points 11a, 11b and the diameter of the collecting chamber 16 are adapted to the smaller diameter 19 remote from the fuse. In this design, the smaller diameter 19 remote from the fuse separates the central section 12 of the conductor 2 when the igniter 7 is activated from the conductor 2, the conductor sections 3a, 3b subsequently serving as a path limit for the separating piston 8 and therefore the fixing of the conductor ends by the screws is particularly cheap. If the step of the piston is inclined (frustoconical), forces act on the conductor sections 3a, 3b in their longitudinal direction, whereby the screws are in turn pressed laterally against the plastic.

A current isolator 1 of the type described above can also be equipped with an additional isolating device for a signal line 18, as shown in FIG Fig. 3 is shown. This additional separating device generally only becomes effective after the conductor 2 has been separated, in order to document the separating process and to initiate any subsequent steps. A separating piston 8 according to the invention in combination with the signal line 18 is shown in FIG Fig. 4 shown.

The separating piston 8 has a predetermined orientation to the conductor 2, which is ensured in the exemplary embodiment by tabs 16a, 16b. The signal line 18 has two ends 19a, 19b and a separating area 20. A pin 21 of the separating piston 8 engages in the separating area 20 of the signal line 18. When the igniter 7 is ignited, the separating piston 8 separates the central section 12 of the conductor 2 and the pin 21 of the Separating piston 8 tears through the signal line 18. In the preferred embodiment, the geometry of the separating area of the signal line 18 and the pin 21 is designed in such a way that the conductor 2 is separated first and only then is the signal line 18 separated. An embossing of the signal line 18 ensures a more precise definition of the tear-off point.

The separating piston 8 ensures the insulation between conductor 2 and signal line 18 before, during and after the separating process.

The assembly is particularly advantageous in that the conductor loop of the signal line 18 protrudes downwards from the upper part 5 after the encapsulation, the separating piston 8 with O-ring 10 is inserted and the conductor loop of the signal line 18 on the interface between the upper part 5 and the lower part 6 and over the pin 21 of the separating piston 8 is bent, after which the lower part 6 is placed and screwed on.

In a so-called leadwire design, i.e. the contact points of igniter 7 and signal line 18 are led out to an external plug, the signal line can be made in one piece. In this case, the signal line is a wire or a stranded wire, which preferably has no insulation in the separation area and is injected into the housing.

Furthermore, in the case of Leadwire variants, where the igniter 7 and the ignition line are also injected in the upper part, it is particularly advantageous if the signal line 18 is also injected in the housing, specifically in the lower part 6.

In a preferred variant, the cables of the ignition line leave the upper part 5 parallel to the conductor level, and the cables of the signal line 18 also leave the lower part 6 parallel to the conductor level, particularly preferably the ignition line and the signal line exit in the same direction. If necessary, a plug connection can also be attached here.

The watertightness of this system can be achieved by a sealing ring - as shown above - mostly in combination with a (four-pole) watertight plug or two (two-pole) watertight plugs.

Claims (11)

1. A pyrotechnic current disconnector (1), in which by pressurisation a conductor (2) is cut, wherein the current disconnector (1) includes a housing which has a lower part (6) and an upper part (5) having an igniter (7), wherein the lower part (6) and the upper part (5) are connected to one another by screws (13a, 13b), and the conductor (2) is inserted between the lower part (6) and the upper part (5) and includes holes (4a, 4b) through which elements extend which fix the conductor (2) in the longitudinal direction, characterised in that the elements which fix the conductor (2) in the longitudinal direction are formed by the screws (13a, 13b) which connect the lower part (6) and the upper part (5) to one another.
2. The pyrotechnic current disconnector according to claim 1, characterized in that the screws (13a, 13b) are insulated from the conductor (2).
3. The pyrotechnic current disconnector according to claim 1 or 2, characterised in that the current disconnector (1) includes a separating piston (8) which upon separating the conductor (2) punches a board (12) from the conductor (2) such that two conductor sections (3a, 3b) separated from one another remain, and in that a collecting chamber (16) for the board (12) and the separating piston (8) is provided on the side of the conductor (2) remote from the igniter.
4. The pyrotechnic current disconnector according to claim 3, characterised in that the collecting chamber tapers away from the conductor (2) so that upon decelerating of board (12) and separating piston (8) a bending moment is created which is absorbed by the screws (13a, 13b).
5. The pyrotechnic current disconnector according to claim 3, characterised in that the separating piston (8) is formed stepwise such that the separating piston (8) hits the conductor sections (3a, 3b) with the step and is thereby decelerated.
6. The pyrotechnic current disconnector according to claim 5, characterised in that the step is inclined.
7. The pyrotechnic current disconnector according to any one of claims 1 to 6, characterized in that the screws (13a, 13b) include heads (15a, 15b), and these heads (15a, 15b) of the screws (13a, 13b) adjoin the lower part (6) and thereby reinforce the housing in an impact region of the separating piston (8) and the board (12).
8. The pyrotechnic current disconnector according to any one of claims 1 to 7, characterised in that the conductor (2) is sealed from the ingress of water against the housing by a seal (17).
9. The pyrotechnic current disconnector according to claim 8, characterized in that the seal (17) is injection-moulded onto the conductor (2).
10. The pyrotechnic current disconnector according to any one of claims 1 to 9, characterized in that the screws (13a, 13b) include a securing device against self-acting loosening and/or against deliberate loosening.
11. The pyrotechnic current disconnector according to any one of claims 1 to 10, characterised in that the screws (13a, 13b) are directly screwed into the lower part (6) or upper part (5) made of plastic and include a thread optimised for adhesion in plastic.

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