Pyrotechnic switch and method for operating a pyrotechnic switch

Abstract

A pyrotechnic switch 30 comprises a busbar 10 connected to a first terminal 31 and a second terminal 32, and a movable part or piston 33 which is moved towards the busbar by a pyrotechnic actuator 34.

Description

The disclosure is related to a pyrotechnic switch and a method for operating a pyrotechnic switch. A pyrotechnic switch includes a first and a second terminal and a busbar that is realized as a conductor and is connected to the first and the second terminal. A pyrotechnic actuator is able to drive a movable part towards the busbar for breaking the busbar. Document US 2U19 / U184so4 Al descrioes a pyrouecnnic swatch for breaking and connecting electrical circuits. The pyrotechnic switch comprises a first and a second electrical conductor. A predetermined disconnection point connects one end of the first electrical conductor to one end of the second electrical conductor. In a normal operating state of the pyrotechnic switch, currents can flow between the first electrical conductor and the second electrical conductor via the predetermined disconnection point. The pyrotechnic switch further has a disconnection bolt which can sever the predetermined disconnection point between the first and. the second electrical conductor after the ignition element is It is an object to provide a pyrotechnic switch and a method for operating a. pyrotechnic switch with an improved breaking characteristic . The object is achieved by the subject-matter of the independent claims. Further developments are described in the dependent craxms. There is provided a pyrotechnic switch, comprising a first and a second terminal, a busbar connected to the first and the second terminal, a movable part, and a pyrotechnic actuator for moving the movable part towards the busbar. The busbar includes a slot. Advantageously, the slot results in a weakness of the busbar in a predetermined area. Thus, a breaking of the busbar is achieved with a high reproducibility. Advantageously, the busbar is xabricared as a single pq. r. x h. n o, t ii e li s x, a r x x a s ex low and predetermined value of resistance before breaking and can easily be mounted. In a development of the pyrotechnic switch, in a first operating state of the pyrotechnic switch, the movable part is apart from the busbar. In a second operating state of the pyrotechnic switch, the pyrotechnic actuator is configured to move the movable part towards the busbar for breaking the busbar . In a development, the pyrotechnic switch is configured such that the movable part hits the busbar in the area of the slot. The movable part has e.g. a sharp edge hitting the busbar at the slot or nearby the slot. In a development of the pyrotechnic switch, the busbar includes a first and a second main side. The slot is located at the first main side of the busbar. The movable part hits the busbar at the first main side of the busbar. Alternatively, the movable part hits the busbar at the second main side of the busbar. In a development of the pyrotechnic switch, a cross-section of the slot has a form of a triangle. The triangle has e.g. a rounded edge at the ground of the triangle. In an alternative development of the pyrotechnic switch, a cross-section of the slot has a form of one of a group comprising a half circle, a circular segment, a U-form and a. rectangle. Thus, in the cross-section, the slot has e.g. two side walls and a ground. The rectangle has e.g. rounded edges at the ground of the rectangle. With rounded edges the recuangle is similar to a slot with U-tom. In a development of the pyrotechnic switch, a depth of the slot is in the range between 20% and 80% of a thickness of the busbar. Alternatively, the depth of the slot is in the range between 40% and 60% of the thickness of the busbar. In a development of the pyrotechnic switch, a width of the busbar has a smaller value than a length of the busbar. The length is e.g. the distance of the first terminal to the second terminal. In a development of the pyrotechnic switch, the busbar has the form of a cuboid. The length is e.g. the length of the cuboid. One end of the cuboid is connected to the first terminal and another end of the cuboid is connected to the second terminal. The busbar has a first to a fourth edge. The first and the second edge are longer than the third and the fourth edge. The first and the second edge of the busbar are parallel to each other. The third and the fourth edge of the busbar are connected to the first and the second terminal. In an example, the busbar is named conductor or pyre conductor. The busbar is made of metal, e.g. copper. In a development of the pyrotechnic switch, at least one tangent line of the slot has a non-perpendicular angle to a centreline of the busbar. The centreline may also be named centreline, middle line or midline of the busbar. Typically, the tangent line is located at a midline of the slot. In case the slot has the form of a straight line, typically one tangent line exists. In case the slot has the form of a curved cine, sever a± tangent zines exrst. In case the slot has the form of a circular ring element, several tangent lines have a non-perpendicular angle to the centreline. In this case the slot may additionally have a tangent line being perpendicular to the centreline of the busbar. Advantageously, at least one tangent line of the slot is not perpendicular to the centreline. Therefore, the slot extends along the length of the busbar. This results in a distribution of the resistance caused by the slot along the length of the busbar. Thus, the heat distribution on the busbar is flattened. The non-perpendicular angle of the slot to the centreline optimizes the cross-section of the busbar which gives a reduced resistance of the busbar. Advantageously, by having the slot for the break in the busbar at an angle instead of perpendicular to the busbar allows the cross-sectional area of the busbar be maximized rather than having a hot spot with the cross-section significantly reduced at one point. The slot results in a predetermined and desired weakness of the busbar. Thus, the slot may be named weakness slot, notch or weakness notch. In an example, this does not have an impact on the breaking force needed for breaking of the busbar during switch firing as this is not dependent on the angle of the slot. In a development of the pyrotechnic switch, the angle of the tangent line with respect to the centreline is in the range between 20° and 70° In a development of the pyrotechnic switch, the angle of the tangent line with respect to the centreline is in the range between 30° and 60°. In an example, the angle is 45°. Advantageously, the by having the slot at an angle the crosssection reduction is not concentrated at one point. Heating due to reduced cross-section is much reduced and also spread along the length of the busbar. In an example, a slight increase of the force to break the busbar may result from the longer length of the slot in comparison to a slot with perpendicular angle to the centreline. This has only a minimal impact and could be assessed by simulation. A depth of the slot or a length of the slot could be changed without much impact to the minimum cross-section. In a development of the pyrotechnic switch, a tangent line of the slot has a perpendicular angle to the centreline. The slot is perpendicular along the width of the busbar. The tangent line of the slot is perpendicular to the first and the second edge of the busbar. This results in a reduced cross-section at this position and may result in an increased resistance, power loss and thus increased heat. Advantageously, such a slot can be easily fabricated. Advantageously, an area useci for the slot on the busbar is minimized. In a development of the pyrotechnic switch, the busbar has a main direction, A current flowing through the busbar has a main path. The angle discussed in this disclosure can also be determined with respect to the main direction of the busbar, 10 the main path of the current in the busbar or the first edge of the busbar instead of the centreline. The slot has e.g. a midline. The slot has a first and a second eoge xormed ox me sxot ano the first marn side of rhe 15 busbar. In a development of the pyrotechnic switch, the slot is realized as a straight line or approximately as a straight line. Thus, the slot has one tangent line. The tangent line 20 may be the midline of the slot. The tangent line is parallel to the first and the second edge of the slot. In an alternative development of the pyrotechnic switch, the slot has a form of a group comprising a circular ring 25 element, a U-form, an arrow and a meander. The tangent line is e.g. a tangent to the midline of the slot. Alternatively, the tangent line is defined as a tangent to the first and the second edge of the slot. 30 In case of the slot being an arrow, the slot has at least two tangent lines. In an example, both tangent lines have a non perpendicular angle to the centreline of the busbar In a development of the pyrotechnic switch, the movable part has an edge that is formed such as the slot. The edge is ctesigned to fit to the slot. The edge and tne scot have the same orientation. The edge and the slot are parallel to each other. The edge has e.g. a form of a group comprising of a straight line, approximately a straight line, a circular ring element, a U-form, an arrow and a meander. For example, the edge hits the slot, in case the movable part hits the busbar at the first main side of the busbar. The edge hits e.g. the area of the slot, in case the movable part hits the busbar at the second main side of the busbar. In a development of the pyrotechnic switch, the slot extends rrom she first, ectge of the busoar co the second ecige of she busbar. Alternatively, the slot has a distance to the first edge and a distance to the second edge. There is provided a method for operating a pyrotechnic switch. According to the method, in a first operating state of the pyrotechnic switch, a movable part is held apart from a busbar. In a second operating state of the pyrotechnic switch, the pyrotechnic actuator is triggered such that a movable part is driven by the pyrotechnic actuator towards the busbar and the movable part breaks the busbar. The busbar includes a slot. Advantageously, the busbar can be broken at the slot by the movable part. Thus, the breaking is realized with nigh reproducibility. The second operating state follows the first operating state. The pyrotechnic switch is particularly suitable for the method for operating a pyrotechnic switch. Features described in connection with the pyrotechnic switch can therefore be used for the method and vice versa. In a development of the method, a tangent line of the slot has a non-perpendicular angle to a centreline of the busbar. Advantageously, the design for the break of the busbar in the pyrotechnic switch reduces resistance and heat by maximizing the cross-sectional area along the conductor. In a development, the slot can be realized as slit, notch, groove, recess and / or cut. In a development, the disclosure is related to an angled slot break pyro. Pyro is tne abbreviation for pyro switch or pyrotechnic switch. The following description of figures of embodiments shall further illustrate and explain aspects of the pyrotechnic switch and the rn.eth.od for operating a pyrotechnic switch. Parts and components with the same structure and the same effect, respectively, appear with equivalent reference symbols. Insofar as parts and components correspond to one another in terms of their function in different figures, the description thereof is not repeated, for each of the following f i q u r e s . Figures 1A ID show an exemplary embodiment of a busbar of a pyrotechnic switch; Figures 2A to 2D show a further exemplary embodiment of a busbar of a pyrotechnic swit Figures 3A to 3H show alternative exemplary embodiments of a busbar of a pyrotechnic switch; and Figures 4A to 4C show exemplary embodiments of a pyrotechnic switch; and Figures 5A and 5B show details of exemplary embodiments of a pyrotechnic switch. Figures 1A to ID show an exemplary embodiment of a busbar 10. In Figures 1A, IC and ID, cross-sections of the busbar 10 are shown. Figure IB shows a top view of the busbar 10. As shown in Figure 1A, the busbar 10 has a slot 11. The slot 11 has tne rorm of a triangle m a cross-section. Thus, the slot 11 has a first and a second edge 13, 14 and a middle line 12. The busbar 10 has a cuboid form. The busbar 10 has a first and a second main side 15, 16. The slot 11 is realized at the first main side 15 of the busbar 10. In Figure IB, a top view on the first main side 15 of the busbar is illustrated. The busbar 10 includes a first to a fourth edge 17 to 20. The first and the second edge 17, 18 form longer sides of the busbar 10. The third and the fourth edge 19, 20 form shorter sides of the busbar 10. The first and the second edge 17, 18 are longer than the third and the fourth edge 19, 20. The third edge 19 is connected to a first terminal 31 of a pyrotechnic switch 30 (shown in Figures 4A to 4C, 5A and 5B). Correspondingly, the fourth edge 20 is connected to a second terminal 32 of the pyrotechnic switch 30. The busbar 10 is made out of metal, for example copper. A metallic conductor of the busbar 10 continues at the third and the fourth edge 19, 20 until the metallic conductor reaches the first and the second terminal 31, 32. The busbar 10 has a centreline 22. In the example shown in Figure IB, the busbar 10 is symmetric with respect to the centreline 22 in a top view. The busbar 10 has a length L and a width W, wherein L >W. A tangent line 23 can be drawn at the slot 11. In this example the tangent line 23 is located on the middle line 12 of the slot 11. The tangent line 23 forms an angle o; to the centreline 22. In the example shown in Figures 1A to ID, the angle a is 90°. In Figure IC, a cross-section of the busbar 10, for example near the fourth edge 20, is shown. In Figure ID, a cross-section of r.he busbar 10 m tne slot il is shown. The slot li has a depth D. The busbar 10 has a thickness T. In Figure ID, the area of the cross-section at the smallest point is shown. Figures 2A to 2D show a further exemplary embodiment of a busbar 10 which is a further development of the embodiment shown in Figures 1A to ID. As illustrated in Figure 2B, the slot 11 is not perpendicular to the centreline 22. The slot 11 has the angle a towards the centreline 22. The tangent line 23 has the angle a towards the centreline 22. The angle a is different from 90°. In the example shown in Figure 2B, the angle a has approximately the value of 60u. Alternatively, the angle c< has approximately the value of 45° or another value. In Figure 2D, the area of the cross-section at the smallest point is shown. In the upper part of Figure 2D, a crosssection of the busbar 10 is shown at the location at which the slot 11 is in contact with the second edge 18. In the lower part of Figure 2D, a cross-section of the busbar 10 is shown in which the slot 11 is between the first and the second edge 17, 18. A reduced cross-section results in an increase or the resistance an tnis point or tie .busbar 10. The locations with the increased resistance are distributed along the length of the busbar 10. Thus, a heat generation is also distributed along the length of the busbar 10. Therefore, hotspots are avoided. Figure 3A shows an alternative exemplary embodiment of a busbar 10 which is a further development of the embodiments shown above. The busbar 10 comprises the slot 11. and a further slot 11'. The further slot 11' is realized such as the slot 11. Thus, the further slot 11' has a further first edge 13', a Further second edge la' and a zurthez middle line 12'. A further tangent line 23' can be drawn at the further slot 11'. The further tangent line 23' is identical or nearly identical to the further middle line 12' of the further slot 11'. The tangent line 23 and the further tangent line 23' have the same angle a towards the centreline 22. In an alternative embodiment, not shown, the angle a' of the further tangent line 23' towards the centreline 22 is different from the angle a of the tangent line 23 towards the centreline 22. In an alternative, not shown embodiment, the angle a' of the further tangent line 23' and the angle a of the tangent line 23 are 90°. Figure 3B shouts an alternative exemplary embodiment of a busbar 10 which is a further development of the embodiments shown above. The slot 11 is realized in the form of an arrow. Thus, a tangent line 23 and a further tangent line 23' can be drawn at the slot 11. The tangent line has an angle a towards the centreline 22 and the further tangent line 23' has a further angle cd towards the centreline 22. Both angles a, a' are e.g. identical. Alternatively, the angles a, a' are e.g. different. Figure 3C shows a further alternative embodiment of a busbar 10 which is a further development of the above-shown embodiments. The slot 11 has the form of a circular ring element. Thus, the middle line 12 of the slot 11 has the form of a part of a circle. Therefore, different tangent lines 23, 23' can be drawn at the middle line 12. One tangent line, not shown, in Figure 3C has an angle a that is equal to 90° to t ne c enu r e 1 me z 2 . no we vs r, most o l cue l ang e m lines ^3^ ^3^ which can be drawn at the middle line 12 have an angle a which is different from. 90° towards the centreline 22. Thus, there is at least one tangent line 23 that has a non-perpendicular angle a to the centreline 22. In the example shown in Figure 3C, the tangent lines 23 and the further tangent lines 23' are shown. Figure 3D and 3E show further exemplary embodiments of a busbar 10 which is a further development of the above-shown embodiments. As shown in Figure 3D and 3E, the slot 11 has a form of a meander in a top view. Figure 3F shows a further exemplary embodiment of a busbar 10 which is a further development of the above-shown embodiments. As shown in Figure 3F, the slot 11 has a form of a rectangle in a cross-section. Figure 3G shows a further exemplary embodiment of a busbar 10 which is a further development of the above-shown embodiments. As shown in Figure 3G, the slot 11 has a torm of a half circle in a cross-section. Alternatively, the slot 11 has e.g. a U-form in a cross-section. Figure 3H shows a further exemplary embodiment of a busbar 10 which is a further development of the above-shown embodiments. The busbar 10 has rounded corners. The slot 11 has the form of a straight line. Due to the chosen dimensions, the middle line 12, the first edge 13 and the second edge 14 are not shown. An angle 3 is defined as angle between the slot 11 and a straight line that is perpendicular to the first and the second edge 17, 18. The angle p has the value of 45°. The centerline 22 and the first and the second edge x / , x 8 axe parallax to e a c n o tn e r. Ine angxe ex can oe calculated as a = 90° - p = 45°. The pyrotechnic switch 30 comprises the first and. the second terminal 31, 32. In this example, the first and the second terminal 31, 32 are realized as openings of the busbar 10. The openings may have the form, of circles. In Figure 3H, a busbar or conductor connection arrangement is illustrated. Figures 4A to 4C show exemplary embodiments of a pyrotechnic switch 30 with a busbar 10 which is a further development of the above-shown embodiments. In Figures 4A and 4B, embodiments of the pyrotechnic switch 30 are shown before break of the busbar 10 and in Figure 4C, an embodiment of the pyrotechnic switch 30 is shown after break of the busbar 10. The pyrotechnic switch 30 comprises the first and the second terminal 31, 32. The busbar 10 is connected, to the first and the second terminal 31, 32. In the examples shown in Figures 4A to 4C, the first and the second terminal 31, 32 are realized as holes, cutouts or apertures of the busbar 10. Moreover, the pyrotechnic switch 30 includes a movable part 33 and a pyrotechnic actuator 34. The movable part 33 comprises an edge 35. The edge 35 arranged in a distance to the busbar 10 before breaking the busbar 10. The pyrotechnic actuator 34 is configured for moving the movable part 33 towards the busbar 10. The edge 35 is that part of the movable part 33 that hits the busbar 10 first after ignition of the pyrotechnic actuator 34. Additionally, the pyrotechnic switch 30 comprises a first part and a second part 37, 38 of a housing. The pyrotechnic actuator 34 and the movable part 33 are arranged in the first part 37 of the housing. A gasket 40 of the pyrotechnic switch 30 provides a seal between the first part 37 of the housing and tne movable part o3. A first g'asket 41 is arranged between the first part 37 of the housing and the busbar 10. A second gasket 42 is located between the second part 38 of the housing and the busbar 10. As shown in Figure 4A, the movable part 33 is adjacent to the second main side 16 of the busbar 10; thus, the slot 11 (which can be named notch) is on a bottom side of the busbar 10 (which can be named conductor). According to Figure 4B, the movable part 33 is adjacent to the first main side 15 of the busbar 10; thus, the slot 11 is at a top side of the busbar 10. The pyrotechnic switch 30 is at normal condition in Figures 4A and 4B: The pyrotechnic switch 30 is able to conduct current between the first and the second terminal 31, As shown in Figure 4C, acrnar3^. dm pdrre UA ' C. UA x—- -A— x-* i x-. -L -L '-f k-, busbar 10 in the area i nt er rup t ed. T her e is after ignition of the pyrotechnic 35 hits the busbar 10 and destroys the of the slot 11. Thus, the busbar 10 is no electrical connection from the first terminal 31 via the busbar 10 to the second terminal 32 after ignition of the pyrotechnic actuator 34 and the shift of the movable part 33. In Figure 4C, the pyrotechnic switch 30 is shown in a position post clearing a fault and / or crash condition. Advantageously, by providing the slot 11, the force for breaking the busbar 10 is reduced and the reliability for breaking the busbar 10 is increased. The breaking of the busbar 10 occurs at the slot 11. Thus, the two parts of the busbar 10 have predetermined forms after breaking of the busbar 10. Figures 5A and 5B show details of exemplary embodiments of a pyrotechnic switch 30 which are further developments of the amove snown emboo.rm.ents. As snown in I igure m, rhe edge aS of the movable part 33 has the form of the slot 11. The edge 35 and the slot 11 have the same orientation. The edge 35 has the form of a straight line. The straight line of the edge 35 is oriented such as the straight line of the slot 11. The straight line of the edge 35 is parallel to the tangent line 23 of the busbar 10. Thus, after ignition, of the pyrotechnic actuator 34, the straight line of the edge 35 hits the slot 11. In Figure 5A, the first main side 15 of the busbar 10 is oriented towards the movable part 33. As elucidated in rigure 5n, ins Hiovaoie part .13 is oriented towards the second main side 16 of the busbar 10. Also in this case, the edge 35 of the movable part 33 is oriented towards the slot 11. The edge 35 and the slot 11 are parallel (since the slot 11 is on the not-shown first main side 1.5, the slot 11 is not shown in Figure 5B). In Figure 5A, the 1 is on top of the busbar 1 the results in a predetermined weak location of the busbar 10, a reliable operation of the pyrotechnic switch 30 is achieved. In an example, the busbar 10 is a single part or single piece berore creaking. in an example, one busbar 10 consists of exactly one part before breaking. In an example, the busbar 10 is broken into two parts or two pieces by the breaking of the busbar 10. In an example, the number of parts of the busbar 10 increases by the breaking of the busbar 10. The embodiments shown in Figures 1A to 5B as stated represent 10 examples of the improved pyrotechnic switch; therefore, they do not constitute a complete list of all embodiments according to the improved pyrotechnic switch. Actual pyrotechnic switches may vary from the embodiments shown in t erms o t parts, sir uc ture s anci shape, i or examoi e . Reference numerals 10 Busbar 11, 11' slot 3 12, 12' middle line 13, 13' first edge 14 , 14 ' second edge 15 first main side 16 second main side 10 17 to 20 edge 22 centreline 23, 23' tangent line 3 0 pyrotechnic switch 31 first rerminal 1 5 32 second terminal 33 movable part 34 pyrotechnic actuator 35 edge 37, 38 part of the housing 2 0 40 to 42 gasket a, a' angle D depth L length T thickness 25 W width

Claims

1. Pyrotechnic switch (30), comprising:- a first and a second terminal (31, 32),5 - a busbar (10) connected to the first and the secondterminal (31, 32),- a movable part (33), and- a pyrotechnic actuator (34) for moving the movable part (33) towards the busbar (10),10 wherein the busbar (10) includes a slot (11), and- wherein at least one tangent line (23) of the slot (11) has a non-perpendicular angle (a) to a centreline (22) extending along a main direction of the busbar (10).xt15 2. Pyrotechnic switch (30) of claim 1,wherein in a first operating state of the pyrotechnic switch (30), the movable part (33) is apart from the busbar (10), and£\J wherein in a second operating state of the pyrotechnic switch 20 (30), the pyrotechnic actuator (30) is configured to move themovable part (33) towards the busbar (10) for breaking the busbar (10).

3. Pyrotechnic switch (30) of claim 1 or 2,25 wherein the pyrotechnic switch (30) is configured such that the movable part (33) hits the busbar (10) in the area of the slot (11).

4. Pyrotechnic switch (30) of one of claims 1 to 3,30 wherein a cross-section of the slot (11) has a form of atriangle .

5. Pyrotechnic switch (30) of one of claims 1 to 3,wherein a cross-section of the slot (11) has a form of one of a group comprising a half circle and a circular segment.

6. Pyrotechnic switch (30) of one of claims 1 to 3,5 wherein a cross-section of the slot (11) has a form of one of a group comprising a U-form and a rectangle.

7. Pyrotechnic switch (30) of one of claims 1 to 6,wherein a depth (D) of the slot (11) is in the range between10 20% and 80% of a thickness (T) of the busbar (10).

8. Pyrotechnic switch (30) of one of claims 1 to 7,wherein the angle (a) of the tangent line (23) with respect1520to the centreline (22) is in the range between 20° and 70°.

9. Pyrotechnic switch (30) of claim 8, wherein the angle (a) of the tangent line (23) with respectto the centreline (22) is in the range between 30° and 60°.

10. Pyrotechnic switch (30) of one of claims 1 to 9,wherein a further tangent line (23') of the slot (11) has aperpendicular angle (cd) to the centreline (22).

11. Pyrotechnic switch (30) of one of claims 1 to 10,25wherein the slot(11)realized asa straightline .

12. Pyrotechnic switch (30) of one of claims 1 to 10, wherein the slot (11) has a form of a group comprising a circular ring element, a U-form, an arrow and a meander.3013. Pyrotechnic switch (30) of one of claims 1 to 12, wherein the movable part (33) has an edge (35) that is formed such as the slot (11).24 10 2414. Method for operating a pyrotechnic switch (30), comprising- in a first operating state of the pyrotechnic switch (30), 5 holding a movable part (33) apart from a busbar (10) , and- in a second operating state of the pyrotechnic switch (30) triggering the pyrotechnic actuator (34) such that the movable part (33) is driven by the pyrotechnic actuator (34) towards the busbar (10) and the movable part (33) breaks the10 busbar (10),wherein the busbar (10) includes a slot (11), and- wherein at least one tangent line (23) of the slot (11) has a non-perpendicular angle (a) to a centreline (22) extending along a main direction of the busbar (10).15

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