WO2020093079A1

WO2020093079A1 - Pyrotechnic current separator

Info

Publication number: WO2020093079A1
Application number: PCT/AT2019/060376
Authority: WO
Inventors: Leyton MUNOZ; Ludwig Marker
Original assignee: Hirtenberger Automotive Safety Gmbh & Co Kg
Priority date: 2018-11-06
Filing date: 2019-11-06
Publication date: 2020-05-14
Also published as: DE212019000419U1; AT521862B1; AT521862A1

Abstract

The pyrotechnic current separator (1) separates a circuit board (3) from a conductor (2) with the aid of a separation punch (14) driven by an igniter (15). An extinguishing agent (13) for extinguishing the electric arc that occurs during the separation is situated behind the separation tool (14). According to the invention, the extinguishing agent (13), during the separation process, is already situated in the region where the conductor (2) passes through the housing before the current flow is completely interrupted. In this way, the join between the conductor and the housing is additionally sealed off by the extinguishing agent (13). Specifically, the conductor may be curved in a U shape, or the two conductor ends (2a, 2b) remaining after the separation process may each have a (loop) contact (23a, 23b), such that, immediately after the mechanical separation, an electrical connection still exists from one conductor end (2a) to the other conductor end (2b) via the contact (23a) of said one conductor end to the circuit board (3) and from said circuit board (3) via the contact (23b) of the other conductor end (2b). Only once the circuit board (3) leaves the region of the contacts (23a, 23b) is the current flow interrupted.

Description

PYROTECHNICAL ELECTRICAL DISCONNECTOR

Technisches GebietTechnical field

The present invention relates to a pyrotechnic current isolator with a housing in which a separating plunger is guided which can be driven by an igniter, a conductor also being passed through the housing, from which a circuit board can be separated when the igniter is ignited by the separating plunger, so that after the separation process, two conductor ends remain at a distance therebetween, and furthermore - seen in the direction of movement of the separation stamp - an extinguishing agent is provided behind the separation stamp to extinguish an arc which arises during the separation process.

Stand der TechnikState of the art

Pyrotechnic isolators are now a common part of the safety concept in the event of an accident in electric vehicles. In conventional vehicles, it was only the 12 V battery that was disconnected, in hybrid vehicles and fully electric vehicles, batteries with voltages up to 1000 V must be reliably disconnected. As a result of the need for greater efficiency, the internal resistances of the batteries decrease and with it the achievable short-circuit currents, which have to be interrupted.

The market offers a variety of pyrotechnic disconnectors, for example the one in the

EP

3103131

A

described current isolator, which is marketed by Autoliv under the name PSS 4.

The applicant has also

WHERE

WO 2017/066816

A

such a current isolator described. This document discloses the preamble of claim 1. These current isolators can separate medium to high currents, but produce massive external effects during the separation process in the form of the escape of hot gases or particles, which can cause short circuits in switch boxes and thus undermine the protective principle of the current isolator or can even lead to fire.

As was determined in the context of the present invention, this is due, inter alia, to the fact that the area where the conductor is led into and out of the housing cannot be adequately sealed (at least not with reasonable effort), so that hot gases and particles can escape to the outside between the conductor and the housing.

Darstellung der ErfindungPresentation of the invention

It is therefore an object of the present invention to provide a current isolator in which the external effect is reduced to a minimum.

This object is achieved according to the invention by a pyrotechnic current isolator of the type mentioned at the outset in that during the disconnection process the extinguishing agent is already in the area where the conductor passes through the housing before the current flow is completely interrupted.

The extinguishing agent is under high pressure during the separation process. If it is already in the area where the conductor passes through the housing before the arc arises, the release agent acts as an additional seal that seals the gap between the conductor and the housing. Such a current isolator therefore has only a minor external impact.

One possible embodiment provides for the conductor to be bent in a U shape, the blank to be punched out being in the back of the U and the back of the U lying in the direction of movement of the separating stamp in front of the area where the conductor passes through the housing .

Another possible embodiment provides that the conductor is essentially flat and that the two conductor ends each have a contact which protrudes from the conductor ends in the direction of movement of the separating stamp, so that an electrical connection continues from an conductor end immediately after the circuit board has been disconnected whose contact to the board and from this board is via the contact of the other conductor end to the other conductor end. So there are two contacts attached to the conductor, at the edge of the (future) conductor ends, so that an electrical connection continues to exist immediately after the mechanical separation. Through the two contacts, a current flow over the board is still possible even after the mechanical separation of the conductor with short-arc arcs between the contact and the board. When moving the circuit board between the contacts, only arcs with a length of less than 2 mm should occur. The electrical isolation takes place only after the circuit board has left the contacts. Since the arcs occurring here have only a small expansion, the energy released and therefore also the external effect are low. A large arc only arises when the circuit board leaves the contacts, but at this point the extinguishing agent is already in the level of the conductor and seals the gap between the conductor and the housing. This also improves the separation performance, because if the gases are let out of the housing through an opening, the separation performance is significantly deteriorated.

When the board leaves the area of the contacts, electrical separation begins by elongating the arcs and interacting with the extinguishing agent. The release of the resulting gases is difficult because extinguishing agent is already on the conductor level and seals the gap between the housing and the conductor.

The distance between the separating punch and the housing is preferably at most 1 mm, preferably at most 0.5 mm. As a result, the arcs are squeezed between the separating stamp and the housing wall, which improves the extinguishing effect. I.e. there is only a small gap between the separating piston and the housing wall after leaving the circuit board in the area of the contacts for the arcing.

The contacts are preferably part of the conductor. This simplifies production.

The extinguishing agent preferably contains silicone. Silicone has the advantage of sealing gaps well in addition to the extinguishing effect.

According to the invention, two effects are achieved: firstly, by at least partially closing the area of the gap between the conductor and the housing with the extinguishing agent, a higher internal pressure is formed, and secondly, the extinguishing agent leads to cooling of any gases still escaping.

The external impact can be further reduced if the current isolator has an additional housing. It is particularly favorable if there is energy-absorbing material in the additional housing, preferably glass, stone or mineral wool.

Kurze Beschreibung der ZeichnungenBrief description of the drawings

The present invention is explained in more detail with reference to the accompanying drawings. 1 shows a current isolator according to the invention in the starting position; 2 shows the same immediately after its triggering; 3 the same in the end position after it has been triggered; 4 shows the current intensity as a function of time, both of a known current isolator and of the current isolator according to the invention; FIG. 5 shows the voltage as a function of the time in turn of the known current isolator and the current isolator according to the invention; FIG. 6 shows the power as a function of the time in turn of the known current isolator and the current isolator according to the invention; and FIG. 7 shows the external effect as a function of the time in turn of the known current isolator and the current isolator according to the invention.

Bester Weg zur Ausführung der ErfindungBest way to carry out the invention

1 shows a current isolator 1 according to the invention in the starting position. The current isolator 1 has a conductor 2. The conductor 2 has a central region 3 which is delimited from the rest of the conductor 2 by

predetermined breaking points

4a, 4b. This results in

conductor ends

2a, 2b. If this central region 3 is broken out of the conductor 2, it is also referred to as a circuit board. In the form shown, the current isolator 1 has an upper housing part 5 and a lower housing part 6. These are held together in an electrically conductive manner by reinforcing

plates

7, 8 and screws (only two

screws

9a and 9b are visible in section). All screws go past conductor 2 on the side. The current isolator 1 thus has an electrically conductive housing which is insulated from the conductor 2 and which, if necessary, can be placed on vehicle ground.

The upper housing part 5 has a bore 10 inside, in which there is a pressure piston 11 with an O-ring 12, an extinguishing agent 13 and a separating punch 14 with an O-ring 14 '. To trigger the current isolator 1, an electrical igniter 15 is provided, which is held in position by an encapsulation 16, which includes a steel disk 17.

The lower housing part 6 also has a bore 18 in the interior, in which a braking element 19 and a base 20 are located. The bottom 20 can have a bore 21. This represents an additional volume if the brake element 19 is compressed during the triggering.

The conductor 2 has two

electrical contacts

23a, 23b which extend from the conductor in the direction remote from the igniter. The distance between the two

contacts

23a, 23b is designed so that it corresponds to the size of the circuit board 3.

Fig. 2 shows the current isolator 1 shortly after tripping. The pressure of the igniter 15 after triggering presses on the circuit board 3 via the pressure piston 11, the extinguishing agent 13 and the separating ram 14 and breaks it out of the conductor 2 along the

predetermined breaking points

4a, 4b. Furthermore, the entire package (pressure piston 11, Extinguishing agent 13, separating stamp 14, board 3) in the direction remote from the igniter. The circuit board 3 moves along the

contacts

23a, 23b. The braking element 19 is compressed and stabilizes the movement of the circuit board 3. If the conductor 2 has a current flowing through it when the circuit board 3 is removed, two arcs are formed between the

conductor ends

2a, 2b or the

contacts

23a, 23b and the circuit board 3. However, these are only very short and therefore have a low energy input. In this state, the conductor is mechanically separated, but is still electrically connected, at least at higher currents.

2, the circuit board 3 is located at the ends of the (sliding)

contacts

23a, 23b remote from the igniter. In the following, the circuit board 3 leaves the area of the (sliding)

contacts

23a, 23b, the arcs between the ends of the (sliding)

contacts

23a, 23b and the circuit board 3 become longer and the actual quenching process begins. At this time, the extinguishing agent 13 is already in the level of the conductor 2 and fills any gaps between the conductor ends 2a, 2b and the upper housing part 5 and lower housing part 6 when pressure is applied. The conductor ends 2a, 2b are fixed in the housing by means of

holes

24a, 24b, in which there are

pins

25a, 25b. With this arrangement, the parting plane between upper housing part 5 and lower housing part 6 is separated from the location of the arcs and protected by the extinguishing agent. A direct escape of hot gases along the conductor 2 is thus avoided. Closing the housing with the extinguishing agent simultaneously increases the pressure in the housing, which means that the arcs can be extinguished better.

Fig. 3 shows the end position of the separating punch 14 and board 3. The braking element 19 is compressed. Up to this position, the electrical resistance of the current isolator 1 increases due to the lengthening of the arcs between the circuit board 3 and the ends of the (sliding)

contacts

23a, 23b, which is reflected in an increase in the voltage curve (see FIG. 5 below). It is particularly advantageous if the arc has already been extinguished when the circuit board has reached the lower position.

4 shows the current profile 31 of a known current isolator and the current profile 32 of a current isolator according to the invention. Both curves start at a current of 17 kA. The starting point is the mechanical separation of the conductor, which can be recognized by a change in the voltage at the current isolator. The curve of the known current isolator begins to decrease rapidly, while the curve of the current isolator according to the invention shows a kind of plateau as long as the circuit board is in the area of the contacts. After leaving the area of the contacts, the current curve shows a sharp drop, which speaks for a good extinguishing effect. The separation time is 0.65 ms in the known current isolator and 0.49 ms in the current isolator according to the invention.

The voltage curves in Fig. 5 show the same behavior pattern. In curve 31 of the conventional current isolator, the voltage rises rapidly because the resistance increases due to the lengthening of the arcs, while the resistance and thus also the voltage on the current isolator according to the invention (curve 32) remains largely constant up to approximately 0.2 ms. After leaving the area of the contacts, the voltage that represents the internal resistance begins to rise sharply because the arcs lengthen and they are in contact with the extinguishing agent. The final quenching peak of the curve of the current isolator according to the invention is cut off at approximately 2100 V, which is due to the measuring range of the devices used. After disconnection, the source voltage of 500 V is present at both current isolators.

The performance curves, which are calculated from current multiplied by voltage, also show the behavior of the two current isolators in FIG. 6. While the power loss 31 of the known current isolator begins to increase rapidly, the power 32 of the current isolator according to the invention initially has a plateau and then begins to increase. The area under the power curves corresponds to the energy. It is significantly influenced by the energy E _Ind , which is stored in an inductance L at a current I (E _ind = I ² · L / 2). In addition, there is an ohmic component, which increases the longer the separation process takes and the arc continues to burn. The known current isolator shows a somewhat higher energy than the current isolator according to the invention.

To quantify the external impact, the current isolators were filmed with a high-speed camera under identical conditions (shutter, aperture, ...) with 120 k FPS. For the analysis, the pixels of each video frame were examined in the HSV color space (HSV = Hue Saturation Value, i.e. hue, saturation, brightness). The HSV color space is a cylindrical color coordinate system in contrast to the RGB color space, which is a Cartesian color coordinate system. The advantage of the HSV system is that the brightness (Value) can be assessed independently of the hue (Hue) and the color saturation (Saturation). This facilitates the detection of the external impact, since only one value needs to be assessed. By definition, the maximum value that the V-value change can reach is 1.

To assess the external impact, the number of pixels was counted that exceed a lower limit of the V value change during the recording and this number is set in relation to the total number of pixels.

The lower limit of the V value change, from which an external effect is counted, was chosen so that the known current isolator has an external effect of approximately 100%. The current isolator according to the invention only has a maximum value of 30%, i.e. the external impact is reduced by more than half.

7 shows the course of the external effect over time. While the normal current isolator (curve 31) shows the external effect immediately at the start of the separation process, this only occurs later with the current isolator according to the invention (curve 32) and with a much lower intensity. Strictly speaking, the majority of the hot gases only appear after the separation process has been completed.

The reduction of the external effect can be further improved by housing the current isolator, in particular if energy-absorbing material, e.g. Glass wool, rock wool or mineral wool. This allows the external impact to be suppressed under the visual observability.

1: Stromtrenner
2: Leiter
2a, 2b: Leiterenden
3: mittlerer Bereich von 2 bzw. Platine
4a, 4b: Sollbruchstellen
5: Gehäuseoberteil
6: Gehäuseunterteil
7: Verstärkungsblech
8: Verstärkungsblech
9a, 9b: Schrauben
10: Bohrung
11: Druckkolben
12: O-Ring
13: Löschmittel
14: Trennstempel
14': O-Ring
15: Zünder
16: Umspritzung
17: Stahlscheibe
18: Bohrung
19: Bremselement
20: Boden
21: Bohrung
23a, 23b: Kontakte
24a, 24b: Löcher
25a, 25b: Stifte

Reference symbol list

1: Current isolator
2nd: ladder
2a, 2b: Conductor ends
3rd: middle area of 2 or board
4a, 4b: Predetermined breaking points
5: Upper part of the housing
6: Lower part of the housing
7: Reinforcement plate
8th: Reinforcement plate
9a, 9b: Screws
10th: drilling
11: Pressure piston
12: O-ring
13: Extinguishing agent
14: Separating stamp
14 ': O-ring
15: Detonator
16: Overmolding
17th: Steel disc
18th: drilling
19th: Braking element
20th: ground
21st: drilling
23a, 23b: contacts
24a, 24b: Holes
25a, 25b: pencils

Claims

Pyrotechnic current isolator (1) with a housing in which a separating plunger (14) is guided which can be driven by an igniter (15), a conductor (2) also being passed through the housing and from which when the igniter (15 ) a plate (3) can be separated by the separating stamp (14), so that two conductor ends (2a, 2b) remain at a distance therebetween after the separation process, and further - behind the separating stamp (14. viewed in the direction of movement of the separating stamp (14) ) an extinguishing agent (13) is provided for extinguishing an arc which arises during the disconnection process, characterized in that during the disconnection process the extinguishing agent (13) is already in the area where the conductor (2) passes through the housing before the current flows is completely interrupted.
Current isolator according to Claim 1, characterized in that the conductor (2) is bent in a U-shape, the blank to be punched out being in the back of the U and the back of the U lying in front of the region, as seen in the direction of movement of the separating stamp (14) where the conductor (2) passes through the housing.
Current isolator according to claim 1, characterized in that the conductor (2) is substantially flat and that the two conductor ends (2a, 2b) each have a contact (23a, 23b) which is in the direction of movement of the separating plunger (14) from the conductor ends (2a, 2b) protrudes, so that immediately after disconnection of the circuit board an electrical connection continues from one conductor end (2a) via its contact (23a) to the circuit board (3) and from this circuit board (3) via the contact (23b) of the other End of the conductor (2b) to the other end of the conductor (2b).
Current isolator according to claim 3, characterized in that the distance between the separating punch (14) and the housing is at most 1 mm, preferably at most 0.5 mm.
Current isolator according to claim 3 or 4, characterized in that the contacts (23a, 23b) are part of the conductor (2).
Current isolator according to one of claims 1 to 5, characterized in that the extinguishing agent (13) contains silicone.
Current isolator according to one of claims 1 to 6, characterized in that the current isolator (1) has an additional housing.
Current isolator according to claim 7, characterized in that there is energy-absorbing material in the additional housing, preferably glass, stone or mineral wool.