The present invention relates to the general field of electrical switching devices, and more particularly to those of the type using pyrotechnic actuation. The invention also relates to an electrical power supply system secured by a device of this type.
Pyrotechnic switching devices are known comprising a body in which is present a pyrotechnic initiator configured, when it is triggered, to set in motion a piston provided with a relief in the direction of a conductive bar, to cut through it. Documents WO 2016/038043 and WO 2016/038050 show examples of devices of this type which allow accomplishing switching in the event of excess current in a circuit.
It would be desirable to switch the current, not only in the event of excess current, but also when a non-electrical anomaly occurs (a shock for example). There exists therefore a need to dispose of a reliable, compact and low-cost switching solution to accomplish this.
The present invention therefore has the purpose of mitigating disadvantages of this type by proposing a pyrotechnic switching device comprising a first and a second pyrotechnic initiators, and a body in which are present:
The device also comprises a fuse element connected in series with the conductive portion and configured to trip when the intensity of the current passing through it exceeds a predetermined value, the first initiator being connected to the terminals of the fuse element so that tripping the fuse element actuates the first initiator, each initiator being configured to cause the switching device to switch from a first current conducting configuration to a second current interrupting configuration, the mobile switching element being set in motion toward the conducting portion in order to break it by the impact of the relief during switching from the first to the second configuration. When the current passing through the conducting portion reaches the tripping threshold of the fuse (predetermined current value), all the current then passes through the first initiator, which also causes its tripping and the interruption of the current due to breakage of the conductive portion. When the second initiator is tripped, for example by means of a control element outside the device, the conductive portion is also broken and the current is interrupted.
The switching device according to the invention thus allows disposing of the advantages of a switching device tripped automatically by overrunning the current threshold (first initiator), and another switching device tripped by another anomaly (second initiator), without the bulk that mounting two devices of this type in series would produce. The use of two distinct initiators which are then tripped by separate connectors allows avoiding coupling between the fuse element and the control element which would result from the use of a single initiator which would be connected both to a fuse element and to a control element. Coupling of this type could then impair the control element in the event of overrunning the threshold value of the current at which the fuse element is tripped. The device according to the invention is thus reliable, simple and compact in design, and preserves the integrity of the control element which can be connected to the second initiator in the event of tripping in response to overrunning the current threshold.
Each initiator can have an output, each output being in communication with a pressurization chamber delimited by the mobile switching element. The mobile switching element can thus separate the pressurization chamber from the chamber in which the conductive portion is present. The mobile switching element can thus be a piston having a cross section of oblong shape in a plane perpendicular to an axis along which it moves in the switching device.
In one exemplary embodiment, the mobile switching element can be configured to break the conductive portion by the impact of the relief at a zone distinct from that where the fuse element is present during switching from the first to the second configuration.
In one exemplary embodiment, the fuse element can be present inside the body. In particular, the fuse element can be present in the chamber in which the conductive portion is present.
In one exemplary embodiment, the fuse element can be present in a second chamber present in the body and distinct from the chamber in which the conductive portion is present. This second chamber can be a cavity present inside the body, for example positioned under the conductive portion.
In one exemplary embodiment, the fuse element can be present in an insulating shell containing a powder of an electrically insulating material.
In one exemplary embodiment, the fuse element can be applied to the conductive portion.
In one exemplary embodiment, the fuse element can consist of a thinned zone of the conducting portion.
In one exemplary embodiment, the mobile switching element can comprise at least one second relief facing the conductive portion, and the conductive portion can have at least one guide slot intended to cooperate with the second relief during switching from the first to the second configuration, the second relief being closer to the conductive portion, in the first configuration, than the insulating relief. This type of positioning improves the reliability of switching. In fact, during switching from the first to the second configuration, and before the impact of the insulating relief on the conductive portion, the second relief will engage in the corresponding slot of the conductive portion and will allow the piston to be guided which still holding in position the conductive portion at the time of impact with the piston. In one exemplary embodiment, the second relief can extend transversely relative to the relief which is intended to impact on the conductive portion. In one exemplary embodiment, the second relief can extend from a lower face of the mobile switching element over a greater distance than the distance over which the relief extends which is intended to impact on the conductive portion of said face.
In one exemplary embodiment, the device can also comprise an additional fuse element connected in parallel to the conductive portion, said additional fuse element being configured to trip when the intensity of the current passing through it exceeds a predetermined value, said additional fuse element having a pre-arc time greater than the time taken by the switching device to switch from the first configuration to the second configuration.
During a normal operation of the system (i.e. when the switching device is in the first configuration), the additional fuse element is conducting, current passes through the conductive portion and the additional fuse element. On the other hand, when the intensity of the current passing through the electrical circuit exceeds the predetermined value for the fuse element connected in series with the conductive portion or when an initiator is tripped by the control element, the switching device switches into the second configuration. The additional fuse element being selected to have a pre-arc time greater than the time taken for disconnecting the conductive portion, the additional fuse element is always conducting at the time when the switching device arrives in the second configuration. In this manner, the additional fuse element short-circuits the switching device, avoiding the appearance of an electric arc within the latter. Secondly, the current circulating in the additional fuse element will melt the latter, which will cause the complete interruption of the electrical current circulating in the circuit. What is meant by “pre-arc time” is, in a manner known per se, the time that the additional fuse element takes to melt and volatilize when a current with an intensity greater than or equal to a predetermined value passes through it.
One advantage of the second fuse element is that the formation of an electric arc at the broken conductive portion is avoided, because the current can still circulate in the additional fuse element during a short period before the latter is tripped and interrupts the circuit. In addition, as the additional fuse element is subjected during this instant to the entire intensity circulating in the electrical circuit, its operation is reliable. This advantageously allows improving the reliability of the electrical switching performed.
In one embodiment, the switching current of the additional fuse element (predetermined current value) can be equal to a nominal electrical current value defined as being less than or equal to four times the maximum value of current intended to circulate in the device in normal operation. In one embodiment, the switching voltage (or breakdown voltage) of the additional fuse element can be greater than or equal to a nominal voltage value defined as being the maximum voltage value intended to be applied to the terminals of the device in normal operation.
The invention also has as its object a secured power supply system comprising at least:
In one exemplary embodiment, the anomaly can be a non-electrical anomaly. What is meant by “non-electrical anomaly” is for example a shock, i.e. a sudden movement of the control element to which the switching device can be connected, or overrunning the temperature or pressure threshold in the environment of the control element.
The invention also applies to a secured electrical system comprising a secured power supply system as defined above, and a device supplied by said secured power supply system. An electrical installation can comprise a secured electrical system of this type.
A secured electrical system of this type can be located, for example, in a motor vehicle, an airplane, a train, a photovoltaic installation, an autonomous domestic installation.
Other features and advantages of the present invention will be revealed by the description given below, with reference to the appended drawings which illustrate an embodiment of it free of any limiting character. In the figures:
The body 10 comprises two lateral openings 11 on two opposite faces of the body 10 (only one lateral opening 11 is visible in
Each of the electrical connectors 21a and 22a of the pyrotechnic initiators 21 and 22 is configured to initiate a pyrotechnic charge 21b and 22b to which they are connected. Each pyrotechnic charge 21b and 22b is, when it is initiated (they can be initiated separately), for example by means of a current passing through the electrical connectors 21a or 22a, capable of generating a pressurization gas by its combustion. According to the invention, the first pyrotechnic initiator 21 is connected, here by means of its connectors 21a, in parallel with the fuse element 50 (i.e. connected to the terminals of the fuse element 50).The second pyrotechnic initiator 22 can be connected by means of its connectors 22a to a control element C (
The piston 30, constituting a mobile switching element within the meaning of the invention, has a cross section of oblong shape in a plane perpendicular to a vertical direction Z of the switching device 1. The direction Z corresponds to the direction in which the piston 30 moves in the switching device 1, and here is perpendicular to the directions L and T. Here the switching device 1 comprises a single piston 30. The piston 30 comprises a circumferential recess 31 in which a seal 32, for example an O ring seal, is intended to be housed. When the piston 30 is in the switching device 1, the O ring seal 32 ensures sealing between the body 10 and the piston 30. The piston 30 can move in the direction Z inside the body 10 between a high position (first position, device in the first configuration), as in
As illustrated in
In conformity with the invention, the piston 30 has an electrically insulating relief. More precisely, the piston 30 comprises here a lower face 34 from which protrudes the relief 33. The relief 33 is positioned facing the conductive portion 40. The relief 33 generally extends here in the transverse direction T. The relief 33 has here a dimension in the transverse direction T which is equal to or slightly greater than the dimension, in this same direction T, of the conductive portion 40. The relief 33 also extends in the direction L and has a nonzero thickness in this direction L. The piston 30 comprises here, on the initiators 21 and 22 side, a skirt 35 delimiting the pressurization chamber 14 and allowing guiding the piston 30 in the body 10.
The conductive portion 40 takes, in the example illustrated, the shape of a plate having a dimension in the longitudinal direction L which is greater than the dimension in this same direction of the body 10 so as to protrude on either side of the switching device 1, through the lateral openings 11. In the example illustrated, the conductive portion 40 comprises two guide slots 41 extending here in the longitudinal direction L, which are intended to cooperate with longitudinal reliefs 36 (second reliefs) protruding on the lower face 34 of the piston 30 after the tripping of an initiator 21 or 22. The longitudinal reliefs 36, in the first configuration, are closer to the conductive portion 40 than the relief 33. The cooperation of the reliefs 36 and the slots 41 allows guiding the piston 30 at the moment of breakage of the conductive portion 40 while still holding it in position, which improves the reliability of switching.
The fuse element 50 takes, in the example illustrated, the shape of a commercial fuse, i.e. it is present in an insulating shell containing a powder of an electrically insulating material. For example, the fuse element 50 can comprise a fusible wire present in silica powder. The fuse element 50 can, as in the example illustrated, be present outside the body or, as a variant, inside the body, as in the examples of
The support 60 takes, in the example illustrated, the shape of a drawer in which the conductive portion 40 is present. In the example illustrated, the support 60 is configured to retain the conductive portion in position in the switching device 1, for example by providing a corresponding housing there. Here the support 60 is equipped with a recess 61 which extends in the transverse direction T and in which the relief 33 is intended to be received after the tripping of one of the pyrotechnic initiators 21 and 22, once the conductive portion 40 has been cut. The recess 61 in the support thus allows locking the piston 30 in the second position and ensuring definitive cutting of the conductive portion 40. Notches 62 corresponding to the longitudinal reliefs 36 can be present in the support 60 to house said reliefs 36 when the device 1 reaches the second configuration.
The operation of the device 1 will now be briefly described in connection with
The switching device 1 described previously has a single conductive portion 40. However, it does not depart from the scope of the present invention if the device has several conductive portions, for example two or three conductive portions, which can be broken simultaneously by the relief of the mobile switching element.
Finally,
Number | Date | Country | Kind |
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1760702 | Nov 2017 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR2018/052819 | 11/13/2018 | WO | 00 |