FR3088592A1 - SAFETY DEVICE FOR VEHICLE ELECTRICAL CIRCUIT - Google Patents

Description

DESCRIPTION

TITLE: SAFETY DEVICE FOR VEHICLE ELECTRICAL CIRCUIT

TECHNICAL FIELD The present invention relates, in general, to the field of protection or safety devices for electrical circuits, in particular for vehicles such as motor vehicles, in particular electric vehicles. More particularly still, the present invention relates to a circuit breaker comprising a pyrotechnic actuator, intended to be arranged in such a vehicle.

These types of vehicles generally all carry at least one battery generally used as an auxiliary energy source in vehicles with an internal combustion engine but which can be used as a main energy source, in particular in electric or hybrid vehicles.

We are increasingly looking to be able to increase the energy storage capacity to increase the range of electric vehicles in particular. However, the power that such energy storage can deliver can be dangerous in the event of a short circuit that may occur during improper handling or in an accident, for example.

To do this, the present invention provides a safety device for cutting a main electrical circuit, as well as a motor vehicle comprising at least one such safety device.

PRIOR ART [0005] Due to the powers involved in such electrical circuits, electrical arcs can form when these circuits pass in particular from a closed state to an open state. These electric arcs can call into question the circuit break, or even its integrity, in the event that they are not controlled. In addition, a good cut-off speed must be provided to limit the risks of overcurrent and / or overvoltage as soon as possible. Faced with these constraints, it is possible to use pyrotechnic circuit-breakers that are well suited for being able to effectively cut these electrical circuits.

Document WO 2015/117998 describes a pyrotechnic circuit breaker, of a reduced size, which provides a quick cut-off. Such a pyrotechnic circuit breaker comprises a housing through which an electrical conductor intended to be cut. This sectioning is obtained by the arrangement, on either side of the electrical conductor, of a punch and of a matrix situated opposite this punch. A control current is generated to activate a pyrotechnic igniter. The pyrotechnic charge of this igniter will propel the punch in a translational movement towards the matrix. In this movement, the punch-die combination will cut the electrical conductor disposed between these two members.

Document WO 2017/042321 describes a protection device comprising a pyrotechnic circuit breaker, as described above, connected in series with a traditional fuse in a power circuit. The pyrotechnic circuit breaker igniter is controlled by an automatically generated current when the fuse blows. In fact, when a short circuit occurs, the strong current flowing through the fuse blows the fuse, which generates an electric arc across the fuse. This electric arc results in the appearance of a large potential difference between the terminals of the fuse, which generates a current in a secondary igniter control circuit mounted in parallel with the fuse. This current activates the igniter which in turn activates the power circuit disconnecting device. This device makes it possible to obtain an independent cut-off of the power circuit since it does not require any control electronics for the pyrotechnic igniter unlike the device described in the previous document WO 2015/117998 which uses an electronic control unit. However, without such electronics, it has no active means of triggering the pyrotechnic igniter. Consequently, this device is not suitable for anticipating potentially dangerous situations because it only allows the power circuit to be opened when the danger is already present.

Also, those skilled in the art know that interfacing any control electronics with a high power circuit is difficult. Indeed, high voltages are rarely compatible with the voltages for which the components of electronic circuits are dimensioned.

Therefore, there is an interest in finding a new more adequate solution which allows, at least in part, to resolve the aforementioned drawbacks. To this end, the invention first of all proposes an autonomous safety device which can also be controlled. The autonomous nature of this safety device aims in particular to be able to operate without external energy supply.

SUMMARY OF THE INVENTION For this purpose, a first aspect of the present invention relates to a safety device arranged to cut a main electrical circuit. This safety device comprises an autonomous tripping element, such as a fuse, arranged to form part of the main circuit, and a pyrotechnic circuit breaker unit. This unit includes at least one electrical conductor connected to the self-triggering element and arranged to be part of the main electrical circuit, as well as a disconnect device configured to sever the electrical conductor. The disconnection device comprises a first igniter, arranged to actuate the disconnection device, electrically connected with the autonomous trigger element so that an actuation of the autonomous trigger element can generate a first firing current of the first igniter. This first firing current being obtained during an opening of the main electrical circuit by the self-triggering element. According to the invention, the pyrotechnic circuit breaker unit further comprises at least one second igniter arranged to actuate the disconnecting device, and arranged to be electrically connected to an electronic control unit configured to generate a second firing current. from the second igniter.

This safety device is preferably a vehicle device, for example a motor vehicle such as a vehicle with a thermal, electric or hybrid engine. The main electrical circuit can typically be a power circuit of such a vehicle for example. The term “self-triggering element” is understood to mean an element arranged to open the main electrical circuit in the event of an overvoltage and / or overcurrent. In what follows, a fuse is said to be blown when the conductive element has been destroyed and that no electric arc can form taking into account the values of the electric voltages present in the electric circuit 1. It then forms an electrically open circuit through which no electric current can flow. A fuse is said to be blowing when the electric current passing through it has exceeded the breaking current, causing the conductive element to start to melt, but the electric voltage across its terminals is higher than the breaking voltage of this fuse, causing the appearance of an electric arc between its terminals. The electric arc continues as long as the fuse is blowing.

Advantageously, the safety device of the present invention makes it possible to cut off the main circuit either when a strong current appears in this main circuit, or by means of a control signal which gives an order voluntary to cut off the main circuit as prevention. Thus, this safety device integrates both a passive trigger system and an active trigger system. The passive tripping system being that which is linked to the fuse and which makes it possible to open the main circuit in the event of proven danger, for example during a short circuit in the main circuit. On the other hand, the active trigger system is one which can be controlled by a control unit, in particular an electrically independent or isolated control unit, in particular the control unit is independent of the main electrical circuit, so as to be protected strong currents that can travel through the main electrical circuit. This active release system enables the main circuit to be opened in the event of a potential danger, for example in anticipation of an imminent accident, like the deployment of an airbag in an identical or similar situation. In conclusion, the device provides reliable protection against strong currents with the first igniter which can be described as a passive igniter, and remains operable if necessary, even in the absence of strong current, with the second igniter, that the 'we can qualify as an active igniter.

In one embodiment, the electrical conductor connected to the autonomous triggering element is preferably mounted in series with the latter. In this embodiment, the actuation of the autonomous tripping element is constituted by the melting of the fuse.

In a preferred embodiment, the cutting device comprises a cutting member which consists of a punch and a matrix located on either side of the electrical conductor. In addition, this sectioning member can be activated by the first igniter or the second igniter. This embodiment makes it possible to concentrate two igniters on the same sectioning member. In other words, two igniters are arranged to be able to actuate a single punch. This configuration makes it possible to obtain a versatile device which is very compact and less expensive than if each igniter has its own sectioning member.

In another embodiment, the sectioning device comprises two sectioning members. In this case, the sectioning device comprises a first sectioning member and a second sectioning member, each consisting of at least one punch and at least one matrix respectively located on either side of the electrical conductor. In addition, the first sectioning member can be activated by the first igniter and the second sectioning member can be activated by the second igniter. Preferably, the two sectioning members are configured to section the same electrical conductor. This electrical conductor is a separate element from the main electrical circuit which is attached to it, namely inserted into the main electrical circuit.

In another embodiment, the firing of one of the two igniters allows the firing of the second igniter. Such a safety device has the advantage of being very reliable because it would make it possible to compensate for the malfunction of one igniter by resorting to the other whatever the cause which generates this triggering.

According to another embodiment, the pyrotechnic circuit breaker unit comprises a first sectioning device forming a first pyrotechnic circuit breaker mounted in series with a second sectioning device forming a second pyrotechnic circuit breaker and where the first cut -pyrotechnic circuit comprises the first igniter and the second pyrotechnic circuit breaker comprises the second igniter. Preferably, the first and second pyrotechnic circuit breakers are identical, which advantageously reduces manufacturing costs and facilitates maintenance, especially in the event of replacement of one of these circuit breakers.

More preferably, the device of the invention is configured to be installed in a motor vehicle and the electronic control unit is configured to activate the triggering of the second igniter during an event such as a sudden deceleration of this motor vehicle. Advantageously, this embodiment makes it possible in particular to prevent any danger, at the level of the main circuit, which may typically arise during an accident or a vehicle crash. This embodiment is therefore advantageously configured in order to be able to acquire a function of anticipating a danger and reacting accordingly, at least as a preventive measure for the safety of objects, such as batteries or vehicle equipment, and of people, such as vehicle users or persons who can work on this vehicle from outside the vehicle.

In one embodiment, the electronic control unit is further configured to activate the triggering of the second igniter by detecting a fault current. This variant may prove useful in the case where the electronic control unit is capable of managing an electrical energy storage member such as one or more batteries in order to be able to also protect this electrical energy storage member against short circuits.

Preferably, the security device further comprises an electrical resistance electrically connected in series with the first igniter.

Finally, in a last aspect, the invention also relates to a motor vehicle comprising at least one safety device according to any one of the preceding embodiments.

Although this safety device is preferably a safety device for a vehicle, it could also be used in other fields, for example in the field of building construction, as an electrical building safety device, or in the field of renewable energies, as a safety device for circuits integrating photovoltaic panels or wind turbines for example.

BRIEF DESCRIPTION OF THE FIGURES Other characteristics and advantages of the present invention will appear more clearly on reading the detailed description which follows and which presents various embodiments of the invention given by way of non-limiting examples and illustrated by the appended figures in which:

- [fig. 1] schematically represents a pyrotechnic circuit breaker

J [0025] - [fig.2] schematically represents the safety device of the invention in a first embodiment;

- [Fig.3] shows a variant of the pyrotechnic circuit breaker of Figure 1;

- [fig.4] schematically shows the safety device of the invention in a second embodiment.

DETAILED DESCRIPTION With reference to FIG. 1, this illustrates a pyrotechnic circuit breaker 10 commonly used in the prior art. This pyrotechnic circuit breaker 10 is crossed by an electrical conductor 5 of a main electrical circuit 1, typically of a power circuit which must be protected or from which people must be protected in the event of a malfunction. The two ends of the electrical conductor 5 typically constitute terminals for connection to the main electrical circuit 1. The electrical conductor 5 generally consists of a copper flat intended to be cut. To do this, the pyrotechnic circuit breaker 10 essentially comprises a sectioning member 13 formed mainly of a punch 14 and a die 15. This die 15 is arranged opposite the punch 14 and in correspondence with the latter. As illustrated in FIG. 1, the electrical conductor 5 is intact and is arranged between the punch 14 and the corresponding matrix 15. When the pyrotechnic circuit breaker 10 is actuated, for example in the event of a short circuit in the main electrical circuit 1, the punch 14 is propelled in a translational movement against the matrix 15. In this movement, the electrical conductor 5 is cut when the punch 14 strikes the matrix 15. The assembly formed by the punch 14 and the matrix 15 constitutes the sectioning member 13 surrounded by the broken line of oval shape in this FIG. 1.

The activation of the pyrotechnic circuit breaker 1 is obtained by a pyrotechnic igniter 12 which can be electrically connected to a secondary electrical circuit for its ignition. The ignition of the pyrotechnic igniter 12, by means of a trigger current flowing in the secondary electrical circuit, will make it possible to ignite the pyrotechnic charge included in the igniter. This explosion will have the effect of propelling the punch 14 towards the matrix 15 and of cutting the electric conductor 5 in passing.

Referring to Figure 2, it schematically shows the safety device of the invention in a first embodiment. This device is arranged to cut the main electrical circuit 1, in particular the electrical conductor 5 of this main electrical circuit. This safety device is preferably a vehicle safety device, in particular of a motor vehicle, for example a thermal or electric vehicle.

The safety device of the invention firstly comprises an autonomous trigger element 20. As illustrated in Figures 2 and 5 appended, this autonomous trigger element 20 could be a fuse, also commonly called circuit breaker with fuse. In this embodiment, the fuse essentially comprises, between its two terminals 21a, 21b, a conductive wire intended to melt to open the main electric circuit 1 when the electric current in this main circuit 1 reaches a value of intensity greater than the threshold maximum that fuse 20 is capable of withstanding for a certain period of time. In another embodiment, this autonomous trigger element 20 could be a magnetic switch and the main electric circuit 1 could be arranged so that when the main electric circuit is traversed by a current greater than a predetermined value, it generates a field magnetic release of this magnetic switch. To do this, several embodiments could be envisaged. In a first example, one could imagine an assembly or device consisting of a coil, of the electromagnet type for example, of a magnetic strip switch, otherwise known by the name "reed switch", and of a source of energy. In this case, the coil would be intended to be able to generate a magnetic field which would make it possible to close the reed switch (due to the sensitivity of this switch to the magnetic field) and to generate a first electric firing current of a first igniter, as described in more detail below. In a second example, one could imagine a coil mounted in the main electric circuit 1 and configured to be able to generate a magnetic field sufficient to close a magnetic switch when the main electric circuit 1 is crossed by an electric current of too high intensity. Closing the magnetic switch, mounted in parallel with the coil, could then allow free passage to an electric current to ignite the first igniter.

The safety device of Figure 2 also includes a pyrotechnic circuit breaker unit 40 arranged in series with the autonomous trigger element 20 in the main electrical circuit 1. This pyrotechnic circuit breaker unit 40 comprises at least one conductor electric 5, connected to the autonomous trigger element 20, and a cutting device 30. The electric conductor 5 is preferably mounted in series with the autonomous trigger element 20. The cutting device 30 is configured to cut the conductor electric 5 and, to do this, comprises a first igniter 31 arranged to actuate the cutting device 30, in particular to actuate at least one piston 14 comparable to the cutting member 13 illustrated in example in FIG. 1.

Furthermore and in the case where the autonomous tripping element (20) is a fuse, the first igniter (31) is electrically connected in parallel with the fuse 20, via a secondary electrical circuit 2, in order to be able to generate a first electric current hi for firing the first igniter 31 by opening of the main electric circuit 1 by the self-triggering element 20. In fact, when the main circuit 1 is crossed by a current I of too high intensity for the element with autonomous triggering 20, the latter will melt or partially melt under the effect of this too strong current. Due to the powers involved in the main circuit 1, an electric arc will then form between the terminals 21a and 21b of the self-triggering element 20 (here in the form of a fuse). The appearance of such an electric arc will also generate a voltage across the terminals of the autonomous triggering element 20. This voltage, associated with the electrical resistivity of the secondary electrical circuit 2, will generate the first firing electric current hi of the first igniter 31.

In the case where the autonomous trigger element (20) consists of a device comprising at least one coil and a reed switch, the operation of such a device could be as follows: by placing the coil between the terminals 21a and 21b (that is to say in place of the fuse previously described), the latter will generate a magnetic field when it is crossed by current I. If this current I is of high intensity, typically during 'a malfunction in the main circuit 1, the magnetic field may be strong enough to activate the reed switch arranged nearby in the secondary electric circuit 2. It should be noted that in this case, the secondary electric circuit would be electrically independent or isolated from the main circuit 1 and would further comprise a source of energy sufficient to generate a first electric current In for firing the first igniter 31 by actuation of the reed switch provided to close the secondary electrical circuit 2. Thus, the reed switch would be open in the rest position and closed in the actuated position. Note that if we consider that the autonomous trigger element 20 is formed of a device consisting of at least one coil, a reed switch and a power source, it does not remain unless this autonomous trigger element 20, in particular the coil of this element, must also be mounted in series with the electrical conductor 5.

According to the invention and as illustrated in Figure 2, the pyrotechnic circuit breaker unit further comprises at least a second igniter 32 arranged to actuate the cutting device, in particular to actuate at least one piston 14 comparable to that of the sectioning member 13 illustrated as an example in FIG. 1. In addition, this second igniter 32 is also designed to be able to be electrically connected to an electronic control unit 50. As this electronic control unit 50 does not necessarily part of the safety device of the invention, it has been shown in broken lines in FIGS. 2 and 5.

Thus, according to the invention, the pyrotechnic circuit breaker unit 40 comprises at least two igniters 31, 32, at least one of which is electrically connected with the autonomous trigger element 20, via a secondary circuit 2 , and the other is designed to be able to be connected to at least one electronic control unit 50. The connection of the first igniter 31 to the terminals 21a, 21b of the autonomous trigger element 20 can be easily carried out for example by means of terminals 41a, 41b of the pyrotechnic circuit breaker unit 40. It will be noted that, by such a connection, the first igniter 31 can be connected to the main electrical circuit 1, via the secondary electrical circuit 2, when the autonomous triggering element 20 consists of a fuse. On the other hand, the electronic control unit 50, in particular the connection to this unit via the terminals 42a, 42b of the pyrotechnic circuit breaker unit 40 (more precisely of the second igniter 32 of this unit), is in all cases isolated from the power circuit, namely from the main electrical circuit 1. The electronic circuits and components of such a control unit 50 are in fact very sensitive to variations and / or high electrical voltages to which they could be subjected. The fact that the connection of the second igniter 32 is independent of the main electrical circuit 1 therefore makes it possible to ensure the protection of the electronic control unit 50 against the undesirable effects generated by the main electrical circuit 1.

With this design, the security device of the present invention can advantageously comprise a passive electrical circuit, materialized by the secondary circuit 2 and the terminals 41a, 41b, and be connected to an active electrical circuit, via terminals 42a, 42b which are intended to electrically connect the second igniter 32 to an electronic control unit 50.

The secondary electrical circuit 2 is qualified as passive due to the fact that the first electrical hi current firing of the first igniter 31 depends on the state of the element with autonomous triggering. Consequently, the first electric current hi cannot be generated on request, for example by a control member such as the electronic control member 50. This passive electric circuit will therefore be activated by the melting of the fuse or by the closing of the reed switch, typically during a short circuit or a fault current in the main circuit 1. In the context of an arrangement of the safety device of the invention in a motor vehicle for example, such a short circuit which can typically occur during improper handling / connection or during an accident through which a shock would cause a malfunction in the main electrical circuit.

The circuit intended to be connected to terminals 42a, 42b of the second igniter 32 is qualified as active because the second electric current It2 for controlling the firing of the second igniter 32 can be generated on request by means of the member. electronic control 50. Consequently, this so-called active circuit will be particularly suitable for situations in which it is advisable to open the main electric circuit 1, as a precaution, to protect the equipment of the power circuit and the persons who may be in contact with it. circuit. Typically, such a situation arises before an impact from the vehicle, like airbags which deploy to prevent injuries to the occupants of a vehicle before an imminent impact. This can also occur during the diagnosis of a malfunction in the electrical circuit, detectable for example by a current measurement device.

Preferably, the electronic control unit 50 is configured to be able to ignite the second igniter 32 and actuate the cutting device 30 independently of the first igniter 31.

According to one embodiment, the cutting device 30 comprises a cutting member 13 such as that of Figure 1 which consists of a punch 14 and a matrix 15 located on either side of the conductor electric 5. In this embodiment, this sectioning member 13 also has the particularity of being activatable by the first igniter 31 or by the second igniter 32.

Referring to Figure 3, this illustrates an example of a first variant 10 'of the pyrotechnic circuit breaker 10 of Figure 1 may be suitable for several embodiments of the present invention. As illustrated in this FIG. 3, two igniters 12a, 12b are arranged so as to be able to actuate the same piston 14. These igniters could typically be the first igniter 31 and the second igniter 32 of any of the embodiments of the invention. Preferably, these igniters 12a, 12b are activated independently of one another.

In an embodiment such as that illustrated as an example in Figure 4, the cutting device 30 comprises a first cutting member 13a and a second cutting member 13b, each consisting of at least one punch 14 and d 'at least one matrix 15 respectively located on either side of the electrical conductor 5. In this case, the first sectioning member 13a is intended to be able to be activated by the first igniter 31 and the second sectioning member 13b is intended to be be able to be activated by the second igniter 32. In addition, the electrical conductor 5 is an element which is common to the two sectioning members 13a, 13b.

As illustrated in Figure 4, the pyrotechnic circuit breaker unit 40 could include a first pyrotechnic circuit breaker 10a mounted in series with a second pyrotechnic circuit breaker 10b, in which the first pyrotechnic circuit breaker 10a comprises the first igniter 31 and the second pyrotechnic circuit breaker 10b comprises the second igniter 32. The first and second pyrotechnic circuit breakers 10a, 10b may be different or identical. In particular, at least one of them may be identical or comparable to the pyrotechnic circuit breaker 10 illustrated in FIG. 1.

According to a preferred embodiment, the security device of the present invention is configured to be installed in a motor vehicle. In this case, the electronic control unit 50 could be configured to activate the triggering of the second igniter 32 during a sudden deceleration of this motor vehicle or the detection of a malfunction.

Again preferably and as illustrated in Figure 4, the secondary circuit 2 comprises a resistive member, such as an electrical resistance 7 for example. Such a resistor 7 will be electrically connected in parallel with the autonomous trigger element 20. As a variant, this electrical resistor 7 could be part of the first igniter 31. Typically, the electrical resistor 7 is at least ten times, preferably at least a hundred times, more resistive than the electrical conductor 5. In this way, and in particular in the case where the autonomous tripping element 20 would consist of a fuse, almost all of the current I of the main electrical circuit 1 will pass through this fuse and an insignificant part will pass through the secondary circuit 2. The secondary circuit, preferably the first igniter 31, will be configured so that this insignificant part is not sufficient to trigger the first igniter 31 and is therefore less than the first electric firing current hi of this igniter 31.

The object of the present invention also relates to a motor vehicle comprising at least one safety device according to one of the variants or one of the embodiments described above.

[0048] Although the objects of the present invention have been described with reference to specific examples, various obvious modifications and / or improvements could be made to the embodiments described without departing from the spirit and the scope. of the invention.

Claims (1)

CLAIMS [Claim 1] Vehicle safety device arranged to cut a main electrical circuit (1) comprising: - an autonomous tripping element (20), such as a fuse, arranged to form part of said main circuit (1), and - a pyrotechnic circuit breaker unit (40) comprising: - at least one electrical conductor (5) connected to the autonomous triggering element (20) and arranged to form part of the main electrical circuit, and - a cutting device (30) configured to cut said electrical conductor (5), said cutting device (30) comprising a first igniter (31), arranged to actuate the cutting device (30), electrically connected with the element with autonomous trigger (20) so that an actuation of the autonomous trigger element (20) can generate a first firing current (In) from the first igniter (31), characterized in that said circuit breaker unit pyrotechnic (40) further comprises: - at least a second igniter (32) arranged to actuate the disconnecting device (30), and arranged to be electrically connected to an electronic control unit (50) configured to generate a second electrical current (If2) for igniting the second igniter (32). [Claim 2] Device according to claim 1, characterized in that said sectioning device (30) comprises a sectioning member (13), consisting of a punch (14) and a matrix (15) located on the side and other of the electrical conductor (5), and that said sectioning member (13) can be activated by the first igniter (31) or the second igniter (32). [Claim 3] Device according to claim 1, characterized in that said sectioning device (30) comprises a first sectioning member (13a) and a second sectioning member (13b), each consisting of at least one punch (14 ) and at least one matrix (15) respectively located on either side of the electrical conductor (5), and that the first sectioning member (13a) can be activated by the first igniter (31) and the second member disconnection (13b) can be activated by the second igniter (32). [Claim 4] Device according to one of the preceding claims, characterized in that the pyrotechnic circuit breaker unit (40) comprises a first sectioning device forming a first pyrotechnic circuit breaker (10, 10 ') mounted in series with a second sectioning device forming a second pyrotechnic circuit breaker (10, 10 '), said first pyrotechnic circuit breaker comprising said first igniter (31) and said second pyrotechnic circuit breaker comprising said second igniter (32). [Claim 5] Device according to claim 4, characterized in that said first and second pyrotechnic circuit breakers are identical. [Claim 6] Device according to one of the preceding claims, characterized in that it is configured to be installed in a motor vehicle and in that the electronic control unit (50) is configured to activate the triggering of the second igniter (32) during a sudden deceleration of this motor vehicle. [Claim 7] Device according to one of the preceding claims, characterized in that the autonomous tripping element (20) is a fuse and in that said vehicle safety device further comprises an electric resistance (7) electrically connected in series with the first igniter. [Claim 8] Device according to claim 7, characterized in that the electrical resistance is at least ten times, preferably at least one hundred times, more resistive than said electrical conductor. [Claim 9] Device according to one of claims 1 to 6, characterized in that the autonomous tripping element (20) is a magnetic switch, the main electrical circuit (1) being arranged so that when it is traversed by a current greater than a predetermined value, it generates a magnetic field for triggering the magnetic switch. [Claim 10] Motor vehicle comprising at least one safety device according to one of the preceding claims.