Pyrotechnic switching element and its use, electric machine therewith, vehicle with switching element or electric machine and method for discharging with this switching element

Abstract

A pyrotechnic switching element (1) is shown. In order to be able to actively short-circuit an electric machine in a stable manner, it is proposed 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) in the bridging position (7b) electrically short-circuits the current conductors (4a, 4b, 4c) as a common neutral point (S) for the phase lines (L1, L2, L3).

Description

[0001] 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.

[0002] 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.

[0003] 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.

[0004] The invention solves the stated problem through the features of claim 1.

[0005] 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.

[0006] Furthermore, by using the bridging element as the star point, the design effort on the pyrotechnic switching element can remain low and a reliable electrical short circuit can be ensured - which leads to high stability with design simplicity in the pyrotechnic switching element according to the invention.

[0007] 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 any additional electrical load on other conductors due to the phases. This can further improve the stability of the pyrotechnic switching element.

[0008] The above can be guaranteed, in particular, if the electrical resistance values ​​from the respective terminal to the bridging element are ≤ 10 milliohms in the bridging position. It is also conceivable that these electrical resistance values ​​are ≤ 5 milliohms, especially in the range of 0.1 to 5 milliohms.

[0009] The operational reliability of the pyrotechnic switching element can be increased, for example, if the pyrotechnic switching element has an electrical insulator that is arranged between the ends of the electrical conductors.

[0010] The electrical insulator could, for example, be a housing section of the pyrotechnic switching element. It is also conceivable that the electrical insulator is provided between the free ends of the electrical conductors.

[0011] Preferably, the electrical insulator has at least one centering 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, ensuring a stable short circuit across the bridging element.

[0012] 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.

[0013] 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.

[0014] For example, each conductor has at least one contact surface, and in particular two contact surfaces, for the bridging element at its ends, especially its free ends, in order to ensure a low-resistance transition to the neutral point. The contact surfaces are preferably arranged on opposite broad sides of the conductors.

[0015] 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, which legs each have a slot between them for the, in particular clamping, engagement of the current conductors in the bridging position.

[0016] 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.

[0017] 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.

[0018] Furthermore, the invention aims to create a method by which at least three phase lines can be reproducibly discharged.

[0019] The invention solves the problem stated with regard to the method by the features of claim 13.

[0020] 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.

[0021] This is particularly advantageous when phase lines of an electric machine in a run-up phase are discharged in order to reproducibly fulfill a safety function.

[0022] 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.

[0023] The figures illustrate, for example, the invention in more detail using one embodiment as an example. They show Fig. 1 is an isometric view of a pyrotechnic switching element, Fig. 2 a sectional view according to II-II of the Fig. 1 , Fig. 3 an exploded view of parts of the pyrotechnic switching element of the Fig. 1 Fig. 4 a sectional view according to IV-IV of the Fig. 1 , Fig. 5 an isometric view of the opened pyrotechnic switching element of the Fig. 1 with its bridging element in bridging position and Fig. 6 a sectional view of the Fig. 5 .

[0024] After the Figuren 1 bis 6 A pyrotechnic switching element 1 is shown. It can be seen after Fig. 1 An electrically insulating housing 2 consisting of a lower housing 2a and an upper housing 2b, and several electrical terminals 3a, 3b, 3c, which are designed as contact tongues. The pyrotechnic switching element 1 serves to switch on an electrical connection between the electrical terminals 3a, 3b, 3c.

[0025] 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. It is also conceivable that the conductors 4a, 4b, 4c are electrically connected to the terminals 3a, 3b, 3c, which has not been shown. 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.

[0026] After Fig. 2 This bridging element 6 is located 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.

[0027] 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 is particularly evident in Fig. 4 can be seen.

[0028] 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.

[0029] As shown in the exploded view after Fig. 3 and also in the Fig. 5 As can be seen from the identical construction of the respective current paths, starting from the electrical terminals 3a, 3b, 3c and extending to the central bridging element 6, their electrical resistances are essentially the same. 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.

[0030] 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.

[0031] 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 11 has a centering groove 16a, 16b, 16c for each free end 13a, 13b, 13c of the conductors 4a, 4b, 4c. The free ends 13a, 13b, 13c of the conductors 4a, 4b, 4c project into these centering grooves 16a, 16b, 16c, thus fixing their position in the housing 2.

[0032] Furthermore, the bridging element 6 in bridging position 7b is precisely aligned and thus positioned relative to the conductors 4a, 4b, 4c. This is ensured by the pyrotechnic switching element 1 having a housing clearance 12 between the electrical conductors 4a, 4b, 4c, into which housing clearance 12 the bridging element 6 engages in bridging position 7b.

[0033] 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, engages these contact surfaces 14a, 14b in a saddle-like manner – as is the case, for example, in the Fig 5 as well as in detail in Fig. 6 recognizable.

[0034] 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.

[0035] 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 α of 120 degrees between each pair of conductors 4a, 4b, 4c arranged next to each other.

[0036] 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.

[0037] 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

1. Pyrotechnic switching element, with several electrical connections, with several 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 by the fact that the pyrotechnic switching element (1) has at least three electrical connections for each phase line (L1, L2, L3) with phases offset from each other, and that the bridging element (6) in the bridging position (7b) electrically short-circuits the current conductors (4a, 4b, 4c) as a common star point (S) for the phase lines (L1, L2, L3).

2. Pyrotechnic switching element according to claim 1, characterized by the fact 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.

3. Pyrotechnic switching element according to claim 1 or 2, characterized by the fact that in the bridging position (7b) the electrical resistance values ​​≤ 10 milliohms, in particular ≤ 5 milliohms, especially in the range of 0.1 to 5 milliohms, resulting from the respective terminal (3a, 3b, 3c) to the bridging element (6) are.

4. Pyrotechnic switching element according to one of claims 1 to 3, characterized by the fact 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).

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

6. Pyrotechnic switching element according to one of claims 1 to 5, characterized by the fact 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.

7. Pyrotechnic switching element according to one of claims 1 to 6, characterized by the fact thatEach 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).

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

9. Pyrotechnic switching element according to one of claims 1 to 8, characterized by the fact that The conductors (4a, 4b, 4c) converge towards each other in a star shape when viewed from above.

10. Pyrotechnic switching element according to claim 9, characterized by the fact thatThere is an angle (α) of 120 degrees between each pair of adjacent conductors (4a, 4b, 4c).

11. Electric machine, in particular electric motor, with a pyrotechnic switching element (1) according to one of claims 1 to 10.

12. Vehicle, in particular a land vehicle, motor vehicle, watercraft or aircraft, with a pyrotechnic switching element (1) according to any one of claims 1 to 10 or with an electric machine according to claim 11.

13. 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 10, 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).

14. Method according to claim 13, characterized by the fact thatPhase lines (L1, L2, L3) of an electric machine in run-up are discharged.

15. Use of a pyrotechnic switching element (1) according to one of claims 1 to 10 for forming a common neutral point (S) for at least three phase lines (L1, L2, L3) connected thereto with phases that are out of phase with each other.

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