Pyrotechnic switch element and use thereof, electric machine having same, vehicle having the switch element or the electric machine, and method for discharging using said switch element

Abstract

The invention relates to a pyrotechnic switch element (1). In order to be able to actively short-circuit an electric machine in a stable manner, it is proposed that the pyrotechnic switch element (1) has at least three electrical connections for a respective phase line (L1, L2, L3) with phases which are phase-offset with respect to one another, and that the bridging element (6) electrically short-circuits the current conductors (4a, 4b, 4c) as a common star point (S) for the phase lines (L1, L2, L3) in the bridging position (7b).

Description

[0001] Pyrotechnic switching element and its use, electric machine herewith, vehicle with the switching element or electric machine and method for discharging with this switching element

[0002] The invention relates to a pyrotechnic switching element with several electrical connections, with several conductors, each connected to a connection or forming these connections as a section, with at least one pyrotechnic charge, and with a bridging element which, in an initial position before ignition of the pyrotechnic charge, is arranged spaced apart from the conductors and, in a bridging position after ignition of the pyrotechnic charge, is in electrical contact with the conductors and electrically short-circuits them.

[0003] Pyrotechnic switching elements are known from the prior art for reliably and quickly triggering a safety-relevant function, such as an active short circuit, on an electrical device, for example, an electric machine. For this purpose, the pyrotechnic switching element comprises two conductors, a pyrotechnic charge, and a bridging element. In its initial position, before ignition of the pyrotechnic charge, the bridging element is spaced apart from the two conductors. In its bridging position, after ignition of the pyrotechnic charge, the bridging element is in electrical contact with the two conductors and short-circuits them. This closes a current path between the two terminals of the pyrotechnic switching element, enabling an electric current flow, for example, to discharge the induced energy of a winding in an electric motor during the overrun.To discharge the typically three phases of an electric machine, not only is a large number of pyrotechnic switching elements required, but also a corresponding design of the electrical connections to ensure voltage equalization between the individual phases. A pyrotechnic safety circuit for an electric machine is therefore comparatively complex and elaborate in design.

[0004] The invention therefore aims to create a pyrotechnic switching element that reduces the design effort and complexity of a pyrotechnic safety circuit. Furthermore, the pyrotechnic switching element should be simple in design and stable.

[0005] The invention solves the stated problem through the features of claim 1.

[0006] In one possible embodiment of the pyrotechnic switching element, it has several electrical connections, each with multiple conductors connected to or forming these connections. It also includes at least one pyrotechnic charge and a bridging element. In its initial position, prior to ignition of the pyrotechnic charge, the bridging element is spaced apart from the conductors. In its bridging position, after ignition of the pyrotechnic charge, the bridging element is in electrical contact with the conductors, short-circuiting them. In particular, the electrical contact between the bridging element and the respective conductors can be formed simultaneously. Advantageously, the bridging element is positioned centrally between the conductors in the bridging position.Furthermore, the pyrotechnic switching element has at least three electrical connections, each for a phase line with phases that are out of phase with each other, with the bridging element in the bridging position electrically short-circuiting the current conductors as a common star point for the phase lines.

[0007] In one possible embodiment of the pyrotechnic switching element, the bridging element simultaneously short-circuits the conductors. This simultaneous short-circuiting occurs either in the bridging position or during the movement into the bridging position. Simultaneously short-circuiting the conductors using a single bridging element has the advantage of being structurally simple to implement and requiring minimal installation space. Furthermore, the short-circuiting can occur faster than, for example, in an embodiment where a bridging element sequentially short-circuits the conductors.

[0008] The use of a single bridging element, preferably arranged centrally to the conductors, which simultaneously short-circuits the conductors electrically, has the additional advantage of resulting in a particularly low overall or contact resistance. This is especially advantageous compared to variants that, for example, require several bridging elements to short-circuit the conductors or in which one bridging element sequentially short-circuits several conductors.

[0009] By having at least three electrical connections, each for a phase conductor with phases offset from one another, the pyrotechnic switching element can discharge and thus actively short-circuit an electric machine in its run-up phase, thereby fulfilling a safety-relevant function. This is possible even with simplified electrical requirements for integration into a safety circuit, since the bridging element, in the bridging position, electrically short-circuits the conductors as a common neutral point for the phase conductors, thus eliminating the need for a complex design for voltage equalization between the individual phase conductors.

[0010] Furthermore, by using the bridging element as the neutral point, the design complexity of the pyrotechnic switching element can be kept low, ensuring a reliable electrical short circuit – resulting in high stability and design simplicity for the pyrotechnic switching element according to the invention. The active short circuit via the pyrotechnic switching element can be further improved, for example, if the electrical resistance values ​​from the respective terminal to the bridging element are essentially the same in the bridging position. In particular, this can also reduce any neutral point voltage that may result from the residual current, thus minimizing additional electrical stress on other conductors due to the phases. The stability of the pyrotechnic switching element can therefore be further improved.

[0011] This can be achieved, for example, by ensuring that the conductors have the same geometric shape and are made of the same material, that the contact area or contact resistance between the bridging element and the respective conductors is the same size, and that the conductors are arranged rotationally symmetrically and equidistant from each other. However, a skilled person can also achieve this in other ways. For example, different geometric shapes of the conductors can be compensated for by individually adjusting the contact resistances between the conductors and the bridging element, so that the resulting electrical resistance values ​​from each connection to the bridging element are essentially the same. Other possibilities are also familiar to a skilled person.

[0012] The above can be guaranteed, in particular, if, in the bridging position, the electrical resistance values ​​from the respective terminal to the bridging element are < 10 milliohms. It is also conceivable that these electrical resistance values ​​are < 5 milliohms, especially in the range of 0.1 to 5 milliohms.

[0013] The operational reliability of the pyrotechnic switching element can be increased, for example, if the pyrotechnic switching element has an electrical insulator arranged between the ends of the electrical conductors. The electrical insulator can, for example, be a housing section of the pyrotechnic switching element's housing. Advantageously, the electrical insulator is a single piece, and particularly advantageously, it is also formed as a single unit with the housing or a housing section. It is also conceivable that the electrical insulator is provided between the free ends of the electrical conductors. The advantage of a single-piece design, or a design in which the electrical insulator is a housing section of the pyrotechnic switching element's housing, is that it greatly simplifies the assembly of the pyrotechnic switching element.

[0014] Preferably, the electrical insulator has at least one hundredweight groove for each end of the electrical conductors, particularly the free end, into which the respective end projects. This positions the conductors precisely relative to each other, which ensures a stable short circuit via the bridging element.

[0015] Preferably, the pyrotechnic switching element has a housing recess between the electrical conductors into which the bridging element engages in the bridging position. This can, for example, position the bridging element more precisely and, while maintaining the specified resistance values, keep any neutral point voltage reproducibly low.

[0016] For a constructive simplification, it is also conceivable that the distances between two ends of the, in particular free, ends of the electrical conductors are each the same, thus resulting in an advantageous geometric centering via the bridging element.

[0017] For example, each conductor has at least one contact surface, and preferably two contact surfaces, for the bridging element at its ends, particularly its free ends, to ensure a low-resistance transition to the neutral point. The contact surfaces are preferably arranged on opposite broad sides of the conductors. The advantage of two contact surfaces is that the transition is particularly low-resistance in this case, thus minimizing potential losses.

[0018] A star point can be created reproducibly if the bridging element is cap-shaped with a, in particular central, bridge and at least three adjoining legs, each leg having a slot between them for the, in particular clamping, engagement of the conductors in the bridging position.

[0019] This can be particularly advantageous if the conductors, when viewed from above, converge in a star shape, thus further reducing any potential neutral point voltage.

[0020] Preferably, there is an angle of 120 degrees between two adjacent conductors. This can ensure more uniform resistance values ​​towards the neutral point as well as improved phase cancellation.

[0021] Furthermore, the invention aims to create a method by which at least three phase lines can be reproducibly discharged.

[0022] The invention solves the problem stated with regard to the method by the features of claim 13.

[0023] By using the pyrotechnic switching element according to the invention, at least three phase lines, which have phases offset from each other, can be reproducibly discharged. For this purpose, the pyrotechnic charge is ignited, and after this ignition, the bridging element, acting as a common neutral point, short-circuits these phase lines. This is particularly advantageous when phase lines of an electric machine in run-up need to be discharged in order to reproducibly fulfill a safety function.

[0024] Preferably, the pyrotechnic switching element according to the invention is used to form a common star point for at least three phase lines connected to it with phases that are out of phase with each other.

[0025] In one possible embodiment of the pyrotechnic switching element, it further includes an additional electrical connection. Furthermore, an additional current conductor is present, which is connected to or forms this additional electrical connection. In the bridging position, the bridging element also contacts the additional current conductor, so that the additional current conductor forms a neutral conductor. The total current can then flow via this neutral conductor.

[0026] The figures illustrate, for example, the invention in more detail using one embodiment as an example. They show

[0027] Fig. 1 is an isometric view of a pyrotechnic switching element,

[0028] Fig. 2 is a sectional view according to 11-11 of Fig. 1 ,

[0029] Fig. 3 is an exploded view of parts of the pyrotechnic switching element of Fig. 1.

[0030] Fig. 4 is a sectional view according to IV-IV of Fig. 1 ,

[0031] Fig. 5 is an isometric view of the opened pyrotechnic switching element of Fig. 1 with its bridging element in bridging position and

[0032] Fig. 6 is a sectional view of Fig. 5.

[0033] Figures 1 to 6 depict a pyrotechnic switching element 1. Figure 1 shows an electrically insulating housing 2 consisting of a lower housing 2a and an upper housing 2b, and several electrical connections 3a, 3b, 3c, which are designed as contact tongues. The pyrotechnic switching element 1 serves to switch on an electrical connection between the electrical connections 3a, 3b, 3c.

[0034] For this purpose, several conductors 4a, 4b, 4c are provided in the housing 2 of the pyrotechnic switching element 1, terminating at and thus forming the terminals 3a, 3b, 3c. On the side of each conductor 4a, 4b, 4c opposite terminals 3a, 3b, 3c, it has a preferably free end 13a, 13b, 13c. However, it is also conceivable that the conductors 4a, 4b, 4c are electrically connected to terminals 3a, 3b, 3c, which has not been shown. A free end is an end 13a, 13b, 13c of a conductor 4a, 4b, 4c which is unconnected or not connected in the initial position 7a.

[0035] The housing 2 also features a pyrotechnic charge 5 and an electrically conductive bridging element 6, for example made of metal, in particular copper or a copper alloy.

[0036] According to Fig. 2, this bridging element 6 is in an initial position 7a, i.e., before ignition of the pyrotechnic charge 5. In this initial position 7a, the bridging element 6 is spaced apart from the conductors 4a, 4b, 4c, so that there is no electrical connection between these conductors. When the pyrotechnic charge 5 is ignited by applying a voltage to an electrical ignition line 8 via an ignition terminal 16 on the pyrotechnic switching element 1, the bridging element 6 is moved towards the conductors 4a, 4b, 4c—in this embodiment, perpendicular to them—namely into a bridging position 7b, in which the bridging element 6 is in electrical contact with the conductors 4a, 4b, 4c and short-circuits them.For this movement towards the conductors 4a, 4b, 4c, the pyrotechnic charge 5 acts on a piston element 9, which is linearly movable along an inner wall 2a of the housing and holds the bridging element 6. A ring seal 9a, for example, is provided between the piston element 9 and the inner wall 2a of the housing to seal off the conductors 4a, 4b, 4c.

[0037] According to the invention, the pyrotechnic switching element 1 is specially designed for this active short circuit. Instead of the usual two terminals, the pyrotechnic switching element 1 has three terminals 3a, 3b, 3c and thus also three conductors 4a, 4b, 4c, as can be seen particularly in Fig. 4.

[0038] Furthermore, in the bridging position 7b, the bridging element 6 electrically shorts the conductors 4a, 4b, 4c as a common neutral point S for the phase lines L1, L2, L3, so that several phase lines L1, L2, L3 can be discharged simultaneously with a single pyrotechnic switching element 1. The bridging element 6 serves as a central voltage equalizer between the individual phases of the phase lines L1, L2, L3, which reproducibly avoids or reduces neutral point voltage. The latter is particularly important in an electric machine with a run-on time, where, due to a reduced motor speed, at least differing voltage amplitudes and / or phase drift are to be expected on the phase lines L1, L2, L3. According to the invention, this can be robustly and reliably accommodated electrically by the bridging element 6 as a common neutral point S.The extremely reliable pyrotechnic switching element 1 also enables a simplified design of a pyrotechnic safety circuit 10. This is because a single pyrotechnic switching element 1 is sufficient to actively short-circuit several phase lines L1, L2, L3 of an electrical machine in order to fulfill a safety-relevant function.

[0039] As can be seen in the exploded view in Fig. 3 and also in Fig. 5, the electrical resistances of the respective current paths, starting from the electrical terminals 3a, 3b, 3c to the central bridging element 6, are essentially the same due to their identical construction. These electrical resistances are all approximately 4 milliohms from the respective terminal 3a, 3b, 3c to the bridging element 6. The use of copper or a copper alloy conductors 4a, 4b, 4c also contributes to this.

[0040] An electrical insulator 11 ensures a sufficiently high dielectric strength and creepage distance at the pyrotechnic switching element 1. The electrical insulator 11, designed as a housing section of the housing 2, is located between the electrical conductors 4a, 4b, 4c and also serves to prevent unintentional contact between the bridging element 6 and the conductors 4a, 4b, 4c.

[0041] Furthermore, the electrical insulator 11 serves to precisely align the conductors 4a, 4b, 4c with respect to the bridging element 6. For this purpose, the electrical insulator has

[0042] 11 For each free end 13a, 13b, 13c of the electrical conductors 4a, 4b, 4c, a centering groove 16a, 16b, 16c is provided. The free ends 13a, 13b, 13c of the electrical conductors 4a, 4b, 4c project into these centering grooves 16a, 16b, 16c - which fixes their position in the housing 2.

[0043] Furthermore, the bridging element 6 in bridging position 7b is precisely aligned and thus positioned relative to the current conductors 4a, 4b, 4c. This is ensured by the pyrotechnic switching element 1 having a housing clearance.

[0044] 12 between the electrical conductors 4a, 4b, 4c, into which housing clearance 12 the bridging element 6 engages in the bridging position 7b.

[0045] The conductors 4a, 4b, 4c each have two lateral contact surfaces 14a, 14b at their free ends 13a, 13b, 13c for the bridging element 6, which in the bridging position 7b with its slots 15a, 15b, 15c surrounds these contact surfaces 14a, 14b in a saddle-like manner - as can be seen, for example, in Fig. 5 and in detail also in Fig. 6.

[0046] For this purpose, bridging element 6 is cap-shaped with a central web 6a and three legs 6b, 6c, 6d adjoining it normally, which have slots 15a, 15b, 15c between them. The clear width of the slots 15a, 15b, 15c is less than the thickness of the conductors 4a, 4b, 4c, which ensures a stable electrical clamping contact between the conductors 4a, 4b, 4c and the bridging element 6.

[0047] The distances A1, A2, A3 between each pair of free ends 13a, 13b, 13c are equal, with the conductors 4a, 4b, 4c converging towards each other in a star-shaped arrangement when viewed from above - with an angle a of 120 degrees between each pair of conductors 4a, 4b, 4c arranged next to each other.

[0048] The pyrotechnic switching element 1 according to the invention is therefore particularly suitable for an electric machine, for example an electric motor, for a vehicle not shown in detail, namely a motor vehicle, in order to actively short-circuit this electric machine and thus discharge its windings via the phase lines L1, L2, L3.

[0049] It is generally accepted that "in particular" can be translated into English as "more particularly". A feature preceded by "in particular" is to be considered an optional feature that can be omitted and therefore does not represent a limitation, for example, of claims. The same applies to "preferably", which is translated into English as "preferably".

Claims

P a t e n t a n s p r ü c h e:

1. Pyrotechnic switching element with multiple electrical connections, with multiple conductors (4a, 4b, 4c) each connected to or forming a connection (3a, 3b, 3c), with at least one pyrotechnic charge (5), and with a bridging element (6) which, in an initial position (7a) before ignition of the pyrotechnic charge (5), is spaced apart from the conductors (4a, 4b, 4c) and, in a bridging position (7b) after ignition of the pyrotechnic charge (5), is in electrical contact with the conductors (4a, 4b, 4c) and electrically short-circuits them, characterized in that the pyrotechnic switching element (1) has at least three electrical connections, each for a phase line (L1, L2, L3) with phases offset from each other, and that the bridging element (6) is in the bridging position (7b) the conductors (4a, 4b, 4c) as common star point (S) for the phase conductors (L1 , L2,L3) electrically short-circuits.

2. Pyrotechnic switching element according to claim 1, characterized in that the bridging element (6) simultaneously short-circuits the current conductors (4a, 4b, 4c).

3. Pyrotechnic switching element according to claim 1 or 2, characterized in that in the bridging position (7b) the electrical resistance values ​​resulting from the respective connection (3a, 3b, 3c) to the bridging element (6) are essentially the same.

4. Pyrotechnic switching element according to one of claims 1 to 3, characterized in that in the bridging position (7b) the electrical resistance values ​​resulting from the respective connection (3a, 3b, 3c) to the bridging element (6) are < 10 milliohms, in particular < 5 milliohms, in particular in the range of 0.1 to 5 milliohms.

5. Pyrotechnic switching element according to one of claims 1 to 4, characterized in that the pyrotechnic switching element (1 ) has an electrical insulator (11 ), in particular as a housing section of a housing (2) of the pyrotechnic switching element (1 ), which is arranged between the, in particular free, ends (13a, 13b, 13c) of the electrical conductors (4a, 4b, 4c).

6. Pyrotechnic switching element according to claim 5, characterized in that the electrical insulator (11 ) has at least one centering groove (16a, 16b, 16c) for each end (13a, 13b, 13c) of the electrical conductors (4a, 4b, 4c) into which the respective end (13a, 13b, 13c) projects.

7. Pyrotechnic switching element according to one of claims 1 to 6, characterized in that the pyrotechnic switching element (1 ) has a housing clearance (12) between the electrical conductors (4a, 4b, 4c) into which the bridging element (6) engages in the bridging position (7b) and / or that the distances (A1 , A2, A3) between two ends of the, in particular free, ends (13a, 13b, 13c) of the electrical conductors (4a, 4b, 4c) are each the same.

8. Pyrotechnic switching element according to one of claims 1 to 7, characterized in that each conductor (4a, 4b, 4c) has at least one contact surface, in particular two contact surfaces (14a, 14b), for the bridging element (6) at least at its, in particular free, ends (13a, 13b, 13c).

9. Pyrotechnic switching element according to one of claims 1 to 8, characterized in that the bridging element (6) is cap-shaped with a, in particular central, bridge (6a) and at least three legs (6b, 6c, 6d) adjoining it, which legs (6b, 6c, 6d) each have a slot (15a, 15b, 15c) between them for, in particular clamping, engagement of the conductors (4a, 4b, 4c) in the bridging position (7b).

10. Pyrotechnic switching element according to one of claims 1 to 9, characterized in that the conductors (4a, 4b, 4c) converge towards each other in a star shape when viewed from above.

11. Pyrotechnic switching element according to claim 10, characterized in that an angle (a) of 120 degrees exists between each of two adjacent current conductors (4a, 4b, 4c).

12. Pyrotechnic switching element according to one of claims 1 to 11, characterized in that an additional electrical connection is included, wherein an additional current conductor is provided which is connected to or forms the additional electrical connection and wherein, in the bridging position, the bridging element also contacts the additional current conductor and thus forms a neutral conductor.

13. Electric machine, in particular electric motor, with a pyrotechnic switching element (1 ) according to one of claims 1 to 12.

14. Vehicle, in particular land vehicle, motor vehicle, watercraft or aircraft, with a pyrotechnic switching element (1) according to any one of claims 1 to 12 or with an electric machine according to claim 13.

15. Method for discharging at least three phase lines (L1 , L2, L3) which have phases offset from each other, with a pyrotechnic switching element (1 ) according to one of claims 1 to 12, in which the pyrotechnic charge (5) is ignited and after this ignition the bridging element (6) short-circuits these phase lines (L1 , L2, L3) as a common star point (S).

16. Method according to claim 15, characterized in that phase lines (L1 , L2, L3) of an electric machine in run-up are discharged.

17. Use of a pyrotechnic switching element (1) according to one of claims 1 to 12 for forming a common star point (S) for at least three connected phase lines (L1, L2, L3) with phases that are out of phase with each other.

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