Protection device for high-voltage applications and method for producing a busbar for such a protection device
Patent Information
- Application Number
- EP2022729144
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-05-12
- Publication Date
- 2025-03-19
Smart Images
Figure 1.1
Abstract
Description
[0001] DESCRIPTION
[0002] Safety device for high-voltage applications and method for producing a busbar for such a safety device
[0003] The invention relates to a fuse device for high-voltage applications with a housing, a first chamber and a second chamber which are formed in the housing, a busbar which extends through the housing and between the first chamber and the second chamber, wherein in the main extension direction of the busbar a first section and a third section of the busbar are fastened in the housing on both sides of the first chamber and the second chamber and the first section is connected to the third section via a second section of the busbar, and a separating body which can be displaced from the first chamber against the busbar and by means of which separating body the second section of the busbar can be displaced in the direction of the second chamber in order to sever the busbar, as well as a method for producing a busbar for such a fuse device.
[0004] Such safety devices are used, particularly in vehicles with high-voltage applications, such as hybrid vehicles or fully electric vehicles, to disconnect the power line between the battery and the consumers, in particular the vehicle's drive, in just a few thousandths of a second, for example in the event of an accident, in order to prevent permanent short circuits. A pyrotechnic igniter is usually used as the trigger. When short circuits are detected, the igniter is activated to open the circuit and prevent personal injury or property damage. The busbar used in the safety device is accordingly disconnected by a device, usually in the shape of a piston, when the pyrotechnic igniter is activated. Care must be taken to ensure that the necessary separation force is not too great, in order to avoid the need to use pyrotechnic igniters that are too large.For this reason, predetermined breaking points are often provided in the area below the piston, where the busbar is to be separated, or around which a rotation takes place on the opposite side, so that these areas serve as a hinge.
[0005] However, these constrictions result in reduced cross-sections available for the current, which leads to increased resistance, making it difficult to ensure the sometimes high current flows.
[0006] For example, DE 10 2004 008 120 A1 describes a pyrotechnic interrupter in which a busbar is mounted in a housing. While sudden notches in the cross-section are avoided, the cross-section of the entire section to be separated is designed with a reduced thickness, with the separation or hinge areas being designed as bevels. While this prevents sudden resistance changes over the length of the busbar, a continuous constriction remains, which impairs the current flow.
[0007] Another disadvantage is that relatively high forces must be applied to separate the busbar, since there is no clearly defined breaking point.
[0008] The objective is therefore to create a safety device and a method for manufacturing a busbar for such a safety device, in which the losses due to the increased resistance can be reduced while simultaneously reducing the separating forces, thus extending the range of an electrically powered vehicle and reducing thermal stress. Furthermore, the production and assembly of such a safety device should be simplified and the space required should be reduced.
[0009] This object is achieved by a safety device for high-voltage applications having the features of main claim 1 and a method for producing a busbar for such a safety device having the features of claim 9.
[0010] The fuse device according to the invention for high-voltage applications has a housing in which a first chamber and a second chamber are formed. A busbar extends through the housing and between the first chamber and the second chamber. The busbar is usually clamped between the two parts of the housing, with one of the chambers being formed in each housing part and being at least partially separated from one another by the busbar. Viewed in the main direction of extension, the busbar has three consecutive sections, with a first section being fastened to one side of the chamber in the housing, a second section at least partially separating the two chambers from one another, and a third section being fastened to the side in the housing opposite the first section. Accordingly, the second section connects the first section and the third section of the busbar to one another.Furthermore, the safety device has a separating body that can be moved from the first chamber towards the busbar. This separating body is designed as a type of piston and is usually accelerated from the first chamber towards the second section of the busbar by firing a pyrotechnic igniter in order to sever the busbar. As a result, the second section of the busbar is either moved completely into the second chamber or is only separated from the adjacent busbar section on one side and rotated around the other adjacent busbar section into the second chamber. The second section of the busbar is arranged offset from the first section and the third section in the direction of movement of the separating body. The busbar thus has a stepped cut, whereby a cross-sectional narrowing only occurs in a differentially small space, so that the electrical resistance in the busbar is only slightly increased.Nevertheless, the remaining connection cross-section between the second section and the adjacent first and third sections is so small that the necessary separation force is significantly reduced.
[0011] Such a busbar is produced according to the invention by a method in which firstly a straight busbar blank is inserted into a tool of a punching or embossing machine between a first tool part and a second tool part. On the side of the first tool part facing the busbar blank, a bulge is formed, while on the side of the second tool part facing the busbar blank, a recess complementary to the bulge is formed, wherein the height of the recess and the bulge is 10% to 60% of the thickness of the busbar. The two tool parts are then moved towards one another with the busbar blank interposed until both tool parts rest against the busbar outside the recess or bulge, and finally the two tool parts are moved away from one another again and the punched busbar is removed from the tool.This tool design creates a fine cut in the busbar, which is typically only carried out close to the breaking point of the busbar, without constricting the cross-section of the busbar over a significant section. This means that a maximum permissible resistance is maintained while still maintaining just sufficient strength. This allows the separation force to be reduced, allowing the fuse to be made smaller, and ensuring the flow of current in the vehicle via the busbar even at high current consumption. The bulge and the recess can be cuboid-shaped, but can also be cylindrical, elliptical, or oval.
[0012] The cross-section of the busbar of the safety device according to the invention preferably corresponds to the cross-section of the second section in the part of the first section and the third section adjacent to the second section. Thus, the same current flow can be ensured across the entire second section as in the adjacent parts of the first section and the third section. A cross-sectional constriction occurs only across a small, differentially small section between the second section and the adjacent first section and third section, which, however, has only a very minor impact on the resistance compared to known designs.
[0013] Furthermore, it is advantageous if the connecting area between the first section and the second section, as well as between the third section and the second section, corresponds to 10% to 60% of the cross-sectional area of the second section of the busbar. The fine-cutting portion is selected so that it is brought close to the breaking point, thereby significantly reducing the required separation force.
[0014] The separating body advantageously has a separating surface facing the second section of the busbar, which is inclined relative to the main extension direction of the busbar. Accordingly, the separating body initially separates the busbar only on one side, further reducing the necessary separating forces. Accordingly, the transition between the first section and the second section serves as a predetermined breaking point, and the transition between the third section and the second section serves as a hinge around which the second section rotates into the second chamber. This can also be used to simplify the extinguishing of any arc that may be present.
[0015] In a further embodiment, a connecting surface between the first section and the second section, which serves as a predetermined breaking point, is smaller than a connecting surface between the first section and the third section, which serves as a hinge. For this purpose, for example, the surface of the piston can be designed at an angle to the busbar, thereby reducing the force required and ensuring that only one-sided separation occurs. This reduces the overall resistance of the busbar.
[0016] In a preferred embodiment, the offset between the second section and the first section and the third section is created by fine blanking, embossing, or punching. All of these cutting processes can be carried out very precisely and produce this type of busbar shape without chipping, which also allows the cross-sectional constriction to be created only differentially small.
[0017] In a further development of this, the offset is produced by precision punching or fine punching. This creates almost burr-free, right-angled cut surfaces, making any further processing unnecessary. In a particularly preferred embodiment of the method, one tool part is guided to the other tool part via at least two guide pins, wherein the busbar has at least one through-hole in the first section and one in the third section, through which one of the guide pins protrudes from a hole in one of the tool parts, through the respective through-hole in the busbar and into corresponding holes in the other tool part. This makes it easy to ensure correct alignment of the busbar between the tool parts and of the tool parts to one another.
[0018] Accordingly, a safety device and a method for manufacturing a busbar for such a safety device are created, which allows a high current flow through significantly reduced resistance while still requiring low separation forces. This allows the force required by the triggering actuator, in particular a pyrotechnic igniter, to be reduced, thus also reducing the size of the entire safety device. The necessary busbar can be manufactured cost-effectively.
[0019] A non-limiting embodiment of a securing device according to the invention and of a tool for manufacturing it is shown in the figures and is described below.
[0020] Figure 1 shows a side view of a pyrotechnic safety device according to the invention in a sectional view before triggering.
[0021] Figure 2 shows a perspective view of the busbar of the safety device according to the invention from Figure 1. Figures 3a) and 3b) show schematically in side view a tool for producing a busbar according to Figure 2.
[0022] The pyrotechnic safety device according to the invention shown in Figure 1 consists of a housing 10 with a first housing part 12, in the interior of which a first chamber 14 is formed, and a second housing part 16, which has an inner receiving opening 18, in which a third housing part 22 forming a second chamber 20 is fastened.
[0023] In the first chamber 14 of the first housing part 12, a separating unit 24 is arranged, which consists of a pyrotechnic igniter 26 in the form of a capsule, which can be electrically ignited via contacts 28, which are directed outwards at a central opening 30 of the first housing part 12, and of a separating body 32.
[0024] An overmolded busbar 43 is arranged between the first housing part 12 and the second housing part 16. This overmold 33 of the busbar 43 forms a first housing plate part 34, which is arranged in a correspondingly shaped receptacle in the first housing part 12 and has an inner opening 36 opposite the first chamber 14, at which the busbar 43 is uncovered. Furthermore, a circumferential groove 38 is formed on this first housing plate part 34, in which an O-ring 40 is arranged, which rests against a shoulder 42 of the first housing part 12. In addition, the overmold 33 has a second housing plate part 44 with an inner opening 45, at which the busbar 43 is also exposed and which is directed towards the second chamber 20. The surface of the overmold 33 or of the second housing plate part 44 facing the second housing part 16 is again located with an O-R interposed.ings 46 against a shoulder 48 of the second housing part 16, wherein the O-ring 46 is arranged in a circumferential groove 50 on the shoulder 48 of the second housing part 16. The first housing part 12 is connected to the second housing part 16 by screws or rivets 52, wherein by establishing the connection the two housing parts 12, 16 are pulled towards each other such that the O-rings 40, 46 seal and clamp the overmolding 33 and thus the busbar 43 to the housing parts 12, 14 and thus to the outside.
[0025] The busbar 43 extends with a first section 54 from outside the housing 10 laterally into the housing 10 and is arranged in the housing 10 between the two housing plate parts 34, 44. The busbar 43 extends further into a second section 56, which is arranged between the first chamber 14 and the second chamber 20, and into a third section 58, which, compared to the first section 54, is clamped between the two housing plates 34, 44 on the opposite side of the chambers 14, 20 and extends further outward from here.
[0026] According to the invention, the busbar 43 has a stepped shape, which means that the second section 56 is arranged offset from the first section 54 and the third section 58 in the direction of the second chamber 20 or in the direction of movement of the separating body 32 upon triggering of the igniter 26, while the first section 54 and the third section 58 are arranged in a common plane.
[0027] As can be seen in Figure 2, the second section 56 has the same thickness as the first section 54 and the third section 58. The regions of the first section 54 and the third section 58 adjacent to the second section 56 also have the same cross-section as the second section 56. The size of connecting surfaces 60 from the second section 56 to the first section 54 and to the third section 58 is approximately 30% of the cross-sectional area of the second section 56 and the adjacent regions of the first section 54 and the second section 56. In other words, the second section 56 is offset from the first section 54 and the third section 58 by approximately 70% of its thickness and has the same width.
[0028] In the present exemplary embodiment, the separating body 32 is designed as a separating piston. A separating surface 62 facing the busbar 43 is inclined to the main direction of extension of the busbar 43. In its rest position, the separating body 32 lies opposite the second section of the busbar 43, with the separating surface 62 being oriented such that the region closest to the busbar 43 is in the immediate vicinity of the connecting surface 60 between the first section 54 and the second section 56 of the busbar 43. Accordingly, the transition region between the first section 54 and the second section 56 forms a predetermined breaking point 64, at which the second section 56 is separated from the first section 54 when the pyrotechnic igniter 26 is triggered by the separating body 32, in that the busbar 43 tears at the connecting surface 60.
[0029] The inclination of the separating surface 62 of the separating body 32 is designed such that when the igniter 26 is triggered, the separating body 32 only bears against the other connecting surface 60 between the second section 56 and the third section 58, so that this connecting surface 60 acts as a hinge 66 around which the second section 56 is rotated during triggering.
[0030] This rotation occurs in the second chamber 20, which serves as an extinguishing chamber in which an arc generated when the pyrotechnic igniter 26 is triggered, which is caused by the separation of the busbar 63 due to the high voltages, is extinguished or discharged into an extinguishing device 67, for which extinguishing agents 69 and / or appropriately shaped cross-sections can be provided. Thus, bores 71 can be formed in the overmolding 33 and / or in the second housing part 16 and / or the third housing part 22, via which bores the second chamber 20 is connected to spaces (not visible in the section of Figure 1) for absorbing the pressure in the first housing part 12.
[0031] If an impact of the vehicle in which the safety device is arranged between a consumer and a battery is detected, for example due to an accident, the pyrotechnic igniter 26 is supplied with power and ignites, causing the chemical mixture contained therein to react exothermically, resulting in expansion. This expansion of the gas takes place in the first chamber 14, which serves as a pressure chamber, whereby a force acts on a closed axial boundary surface 68 of the separating body 32 in the direction of the busbar 43, which is arranged adjacent to the separating body 32. Accordingly, when the pyrotechnic igniter 26 is triggered, the pressure in the pressure chamber is increased to such an extent that the separating body 32, with its separating surface 62, is moved at high speed against the second section 56 of the busbar 43 between the predetermined breaking point 64 and the hinge 66.The force causes the busbar to break at the predetermined breaking point 64 and the flow of current is interrupted.
[0032] The separation of the busbar 43 is significantly simplified by the predetermined breaking point 64 and the hinge 66, which means that a significantly lower separation force is required compared to known designs. Nevertheless, the differentially small constriction in the area of the connecting surfaces 60 allows for an almost unhindered flow of current.
[0033] The busbar 43 according to the invention is first cut to the desired length, for example, from a rolled copper strip. This busbar blank 68 is inserted, as shown in Figure 3a), into a tool 70 of a punching or stamping machine, specifically between a first tool part 72 and a second tool part 74. This tool is shown in a very simplified manner in the figure, but a variety of fine blanking or fine-blanking tools are known, which of course have several additional tool parts.
[0034] The first tool part 72, which forms the movable, upper tool part 72 in Figure 3a), has a cuboid-shaped bulge 76 on its surface facing the busbar, in this embodiment, while the second, lower and stationary tool part 74 has a complementary recess 78 formed on the side of the busbar 43 opposite the bulge 76. To ensure that the busbar 43 is correctly aligned with the two tool parts 72, 74 and that the tool parts 72, 74 are correctly aligned and guided with respect to one another, the tool parts 72, 74 each have two holes 80, 82 arranged on either side of the recess 78 or the bulge 76. Guide pins 84 are fixedly arranged in the holes 82 of the second tool part 74, which protrude from the second tool part 74 through two correspondingly shaped through holes 86 in the busbar 43 and into the holes 80 of the first tool part 72.The through holes 86 of the busbar 43 are formed in the first section 54 and in the third section 58 of the busbar.
[0035] The first tool part 72 is then guided by the guide pins 84 and pressed towards the second tool part 74, whereby additional counterforces can also be generated. As a result, the bulge 76 is pressed against the second section 56 of the busbar blank 68. The latter is pressed into the recess 78 by the resulting shear stress. This creates a fine-cut surface 88 at which the second section 56 is cut and severed from the first section 54 and the third section 58. The height of the bulge 76 and the recess 78 are, however, selected such that this cut does not continue to the lower edge of the busbar 43, but rather the cutting portion in this example is only approximately 70%. After traversing the corresponding height, the first tool part 72 rests almost entirely against the busbar 43 and a residual fracture portion remains which acts as a connecting surface 60, as shown in Figure 3b).
[0036] This creates a busbar which, on the one hand, significantly reduces the necessary separation forces and, on the other hand, only slightly increases the electrical resistance due to the differentially small section with reduced cross-section.
[0037] It should be clear that the scope of protection is not limited to the described embodiments, but various modifications are possible. For example, the busbar manufactured according to the invention can also be used for other purposes. Modified tools can also be used, or the other tool part can be moved or have the bulge or recess. The guide can also be designed differently. The safety device can also be designed very differently. For example, the busbar can also be separated on both sides by an appropriately designed separating body. Actuation does not necessarily have to be via an igniter. The housing divisions can also be designed differently.
Claims
P A T E N T A N S P R Ü C H E 1. A safety device for high-voltage applications comprising a housing (10), at least a first chamber (14) and a second chamber (20) formed in the housing (10), a busbar (43) extending through the housing (10) and between the first chamber (14) and the second chamber (20), wherein, in the main direction of extension of the busbar (43), a first section (54) and a third section (58) of the busbar (43) are fixed on both sides of the first chamber (14) and the second chamber (20) in the housing (10), and the first section (54) is connected to the third section (58) via a second section (56) of the busbar (43), and a separating element (32) displaceable from the first chamber (14) against the busbar (43), through which the second section (56) of the busbar (43) is displaceable to cut the busbar (43) in the direction of the second chamber (20). is characterized bythat the second section (56) of the busbar (43) is arranged offset from the first section (54) and the third section (58) in the direction of movement of the separating body (32).
2. Safety device for high-voltage applications according to claim 1, characterized in that the cross-section in the part of the first section (54) and the third section (58) adjacent to the second section (56) corresponds to the cross-section of the second section (56). A safety device for high-voltage applications according to claim 1 or 2, characterized in that a connecting surface (60) between the first section (54) and the second section (56), as well as between the third section (58) and the second section (56), corresponds to 10% to 60% of the cross-sectional area of the second section (56) of the busbar (43). A safety device for high-voltage applications according to any one of the preceding claims, characterized in that the separating element (32) has a separating surface (62) facing the second section (56) of the busbar (43), which is inclined to the main direction of extension of the busbar (43). A safety device for high-voltage applications according to claim 4, characterized in that a transition between the first section (54) and the second section (56) serves as a predetermined breaking point (64) and a transition between the third section (58) and the second section (56) serves as a hinge (66).Safety device for high-voltage applications according to claim 5, characterized in that a connecting surface (60) between the first section (54) and the second section (56), which serves as a predetermined breaking point (64), is smaller than a connecting surface (60) between the first section (54) and the third section (58), which serves as a hinge (66). Safety device for high-voltage applications according to any of the preceding claims. characterized in that the offset between the second section (56) and the first section (54) and the third section (58) is produced by fine blanking, embossing, or stamping. A fuse device for high-voltage applications according to claim 7, characterized in that the offset is produced by precision stamping or fine blanking. A method for producing a busbar for a fuse device for high-voltage applications according to any of the preceding claims, characterized in that a busbar blank (68) extending straight is inserted into a tool (70) of a stamping or embossing machine between a first tool part (72) and a second tool part (74).wherein a protrusion (76) is formed on the side of the first tool part (72) facing the busbar blank (68) and a recess (78) complementary to the protrusion (76) is formed on the side of the second tool part (74) facing the busbar blank (68), wherein the height of the recess (78) and the protrusion (76) is 10% to 60% of the thickness of the busbar blank (68), the two tool parts (72, 74) are then moved towards each other with the busbar blank (68) interposed until both tool parts (72, 74) are in contact with the busbar (43) outside the recess (78) and the protrusion (76), respectively, and finally the two tool parts (72, 74) are moved apart again and the stamped busbar (43) is removed from the tool (70). Method for manufacturing a safety device for high-voltage applications according to claim 9, characterized in that one tool part (72; 74) is guided to the other tool part (74; 72) via at least two guide pins (84), wherein the busbar (43) has at least one through-hole (86) in the first section (54) and in the third section (58), through which one of the guide pins (84) projects from a hole (80; 82) in one of the tool parts (72; 74) through the respective through-hole (86) in the busbar (43) and into corresponding holes (82; 80) of the other tool part (74; 72).