METHOD FOR PRODUCING A CONDUCTOR FOR A CURRENCY DISCONNECTOR, CONDUCTOR FOR A CURRENCY DISCONNECTOR AND CURRENCY DISCONNECTOR

Description

Technical area

[0001] The present invention relates to a method for producing a conductor for a current isolator, which has a circuit board to be separated between two conductor ends. The conductor has a conductor overmolding that has a cavity in which the circuit board is located. Furthermore, plastic melt is injected via at least one sprue into an injection mold in which the conductor is located. It further relates to a conductor with a conductor overmolding that can be produced by such a method, as well as to a current isolator with such a conductor. State of the art

[0002] Pyrotechnic current isolators are becoming increasingly widespread in electric vehicles. This is because low-power vehicles can be reliably protected by a combination of contactors and fuses, whereas with medium and higher power outputs, a current range develops between the current-carrying and isolating capacity of the contactors and the timely tripping range of the fuse, which is not adequately protected. There are many examples of current isolators in the high-voltage range. patcit0001:AT 522735 B --. by Hirtenberger shows a typical design. A characteristic element of these current isolators with greatly reduced external impact is an overmolding of the conductor, which avoids or at least minimizes a continuous gap between the plastic of the housing and the conductor, thus preventing the escape of hot gases. patcit0002:WO WO 2021 / 168493 A --. also shows a design with a pyrotechnic current isolator with conductor, isolating piston, and conductor overmolding. In this case, projections are provided in the injection molding tools so that the conductor is notched during injection molding. This represents a cost-effective way of notching the conductor. patcit0003:WO WO 2021 / 207773 A --. shows a pyrotechnic current isolator with a similar structure to patcit0004:WO WO 2021 / 168493 A --. However, at least one predetermined breaking point of the conductor is filled with polymer material to improve the stability of the conductor.patcit0005:DE 10065535 A --. describes a method for producing a busbar at least partially cast with cast resin for connecting a motor vehicle lamp unit, the production method using a casting mold which guides the cast resin to the busbar via a sprue and a sprue distributor, the busbar partially cast with cast resin having a cavity and the sprue and the sprue distributor are arranged in a lateral edge region of the busbar outside the cavity. patcit0006:JP H0774451 A --. describes a method for producing a cast printed circuit board arrangement which has a cavity, the production being carried out by placing a flexible printed circuit board in a casting mold and the thermoplastic resin flowing to the flexible printed circuit board via a sprue, the sprue taking place from the cavity.

[0003] In injection molding, a distinction is made between the sprue, the sprue distributor, the gate, and the actual injection-molded part. The sprue is the feed pipe, which usually widens conically, or rather the material that remains there after demolding. The sprue distributor refers to the channels that extend from the sprue to the actual injection-molded part, or rather the material that remains there after demolding. A sprue distributor is only necessary if the sprue does not open directly into the actual injection-molded part. The gate is the transition from the sprue (or sprue distributor, if present) to the actual injection-molded part. Normally, this is where the sprue distributor and sprue are separated, cut off, from the injection-molded part. Finally, a filling space is sometimes provided between the sprue and the sprue distributor so that the channels of the sprue distributor are evenly supplied (filled) with material.The material remaining there after demoulding is referred to below as filling space plastic.

[0004] Until now, the conductor overmolding has been produced using (at least) two external sprues. The difficulty with this conductor overmolding process lies in the distortion of the conductor overmolding and the formation of weld lines in the area of ​​the conductor overmolding that is particularly subject to pressure from a possible arc. This is because the material cools significantly on its way to the inside, where the arc forms. A weld line is the area where the plastic coming from one sprue (or a channel of a sprue distributor) joins the plastic coming from another sprue (or another channel). The strength is often reduced there because the plastic is already relatively cool at the time of merging, meaning the two plastic strands no longer fuse completely. Description of the invention

[0005] It is an object of the present invention to provide a method of the type mentioned at the outset in which these difficulties occur to a lesser extent.

[0006] This object is achieved according to the invention by a method of the type mentioned at the outset in that the sprue is made from the cavity through which the conductor is passed, wherein the plastic melt flows from the sprue to the actual conductor overmolding through a sprue distributor.

[0007] According to the invention, injection molding takes place from the inside out, so that the material on the inside of the conductor overmolding, i.e., at the edge of the cavity where the arc forms, is still relatively hot when it flows together from various channels of the sprue manifold. Warpage is also reduced because the sprue manifold prevents the injection-molded part from shrinking differently in different directions.

[0008] The sprue and sprue manifold can be removed from the conductor overmolding, resulting in a product similar to the state of the art. This can be easily accomplished in the injection mold, for example, by punching or using an ejector.

[0009] Alternatively, the conductor can be provided with a hole, and the sprue can be separated using a punch inserted through this hole. When producing the conductor overmolding, care should be taken to ensure that the sprue does not have an increase in cross-section behind the hole, as far as possible, to avoid unnecessarily complicating separation.

[0010] A third possibility is to remove the sprue and sprue distributor by turning the sprue.

[0011] Advantageously, however, the sprue remains in the conductor overmolding, resulting in a conductor in which the sprue and sprue distributor are located in the cavity of the conductor overmolding. This allows for additional functions, such as centering the circuit board during further assembly of the current isolator. When the current isolator is triggered, the sprue and sprue distributor are separated from the conductor overmolding in the area of ​​the gates. In a current isolator in which such a conductor is installed, the circuit board can be decelerated during the separation process: The usually conical sprue can, for example, be decelerated in a cylindrical bore.

[0012] The strength of the connection between the sprue and the blank can be increased if the sprue manifold is at least partially umbrella-shaped. "Umbrella-shaped" means that the sprue manifold has the shape of a circular disk; "partially umbrella-shaped" means that it has the shape of at least one circular sector. Compared to thin channels, an umbrella-shaped or partially umbrella-shaped design results in a more even distribution of the liquid plastic and also a more stable connection between the conductor overmolding and the sprue. The sprue manifold, which can consist of several channels or, as mentioned above, can also be umbrella-shaped, can be supplied with the plastic melt directly from the sprue or via a filling chamber. Supplying the plastic melt via a filling chamber has the advantage during production that it ensures even distribution of the plastic melt, which is otherwise difficult to achieve, especially with an umbrella-shaped sprue manifold.In this case, the finished product will have a filler plastic between the sprue and the sprue manifold that extends further toward the cavity wall than the sprue itself. Since the filler plastic normally rests against the conductor, this also increases the strength of the connection between the sprue and the conductor.

[0013] To increase the strength of the connection between the sprue and the blank, it is further advantageous if the blank has a hole and at least a portion of the sprue extends through this hole, preferably with a larger cross-section behind the hole than the cross-section of the hole itself. In contrast to the above-described design, in which the sprue is cut through the hole using a punch, an enlarged cross-section behind the hole is advantageous here.

[0014] According to one embodiment of the invention, the sprue distributor is formed by a plurality of channels whose connection to the conductor overmolding occurs in the lateral edge region of the conductor, in particular that the connection of the channels to the conductor overmolding touches predetermined breaking points of the conductor. This means that the gates are located where the lateral edges of the conductor enter the conductor overmolding. This can be achieved, for example, by four gates next to the conductor in the conductor plane. The geometry of the groove (usually U-, V-, or W-shaped) can in this case be continued in the gate region. This is advantageous in that the core of the injection mold, which has a projection extending into the predetermined breaking points, can be designed with circular symmetry. The predetermined breaking points are then partially filled by the plastic, namely in the remaining gap between the projection of the core and the predetermined breaking point.

[0015] It is advantageous if the channels are arranged in pairs opposite each other, relative to the axis of the cavity of the conductor overmolding. This symmetry minimizes distortion during cooling. It is particularly advantageous if there is also symmetry with respect to the plane containing the longitudinal axis of the conductor and the axis of the cavity, and / or with respect to the plane containing the normal to the longitudinal axis of the conductor and the axis of the cavity.

[0016] Alternatively, it is also possible to provide for the connection of the sprue distributor to the conductor overmolding in a plane that is at a distance from the conductor, preferably a distance of at least 1 mm, particularly preferably at least 2 mm. This results in a particularly high insulation resistance after the separation process. This is because when the conductor is separated, the sprue is also separated from the conductor overmolding, specifically in the region of the gates. This creates rough areas on which residues from the burnt-off copper tend to settle after separation. If these have no direct contact with the conductor, this is beneficial for the insulation resistance. In the simplest case, this distance is created by offsetting the parting planes of the cores of the overmolding tool, provided that the gate is made across this plane. The offset is preferably in the direction of the igniter.

[0017] The gates are also spaced from the conductor when the sprue manifold has two manifold channels perpendicular to the conductor's longitudinal axis. This arrangement minimizes distortion of the cavity. Without special measures, shrinkage in the conductor area would be less than at right angles to it, because the conductor counteracts shrinkage. If the channels are perpendicular to the conductor's longitudinal axis, they also resist shrinkage in this direction, reducing the deviation from the ideally circular cross-section. A further advantage is that the weld lines form in the area reinforced by the conductor.

[0018] As mentioned above, the gates can be located in the conductor area, which requires, in particular, that they be located in the conductor plane. For this purpose, it is advantageous if the conductor has a reduced cross-section in the area where it enters the conductor overmolding, with the reduced cross-section preferably being formed by lateral cuts on the conductor. This provides additional space for the gates.

[0019] As previously described for the variant with the sprue remaining in the conductor overmolding, the gate can also be in contact with the conductor or away from it in the variants with the sprue removed. If the gates are not in contact with the conductor, the same advantages as previously described apply. This also applies to offsetting the gates from the conductor plane. Short description of the drawings

[0020] The present invention is explained in more detail with reference to the accompanying drawings. They show: Fig. 1a a pyrotechnic current isolator with a housing base, a housing top and an intermediate conductor with a conductor overmolding having a sprue and a screen-shaped sprue distributor; Fig. 1b the conductor overmolding from below; Fig. 1c the conductor in top view; Fig. 1d a section along the line Id-Id in Fig. 1b ; Fig. 1e a section along the line Ie-Ie in Fig. 1b ; Fig. 2a another embodiment of a conductor overmolding from below, with four diagonally arranged distribution channels; Fig. 2b a section along the line IIb-IIb in Fig. 2a ; Fig. 3a and 3b Views similar to Fig. 2a and 2b , but with a filling space between the sprue and the distribution channels; Fig. 4a and 4b Views similar to Fig. 3a and 3b, but with a conductor with a central hole; Fig. 5a another embodiment of a conductor overmolding from below, with two distribution channels normal to the longitudinal axis of the conductor; Fig. 5b a section along the line Vb-Vb in Fig. 5a ; Fig. 5c a section along the line Vc-Vc in Fig. 5a ; and the Fig. 6a to 6c show views similar to the Fig. 5a to 5c , but with cuts below the conductor level and with a conductor with a central hole. Way(s) of carrying out the invention

[0021] The Fig. 1a shows a pyrotechnic current isolator, designated overall by 11. This has a housing composed of a lower housing part 12, an upper housing part 13, and an intermediate conductor overmolding 15 for a conductor 14. The individual parts are held together by four screws 16.

[0022] The conductor overmolding 15 is formed by placing the conductor 14 in an injection mold and then producing the conductor overmolding 15 by injection molding. This has the advantage that, due to the manufacturing process, there can be no gap between the conductor overmolding 15 and the conductor 14; the conductor overmolding 15 fits tightly against the conductor 14 even without any additional seals. To seal the housing, it is therefore sufficient to seal the housing bottom part 12 and the housing top part 13 against the conductor overmolding 15, which is relatively easy to do because, unlike the conductor 14 produced by stamping, injection-molded parts do not have sharp edges. For example, a groove 12a can be provided into which an O-ring is inserted.

[0023] The conductor overmolding 15 has a central cavity 20. A separating piston 19 is arranged in this cavity 20 between the conductor 14 and the upper housing part 13. A pyrotechnic igniter 17 is arranged in the upper housing part 13. This igniter can be connected to an electronic circuit via a connector 18. When the electronic circuit generates an ignition signal, the igniter 17 suddenly generates excess pressure, which presses the separating piston 19 against the conductor 14, thereby breaking out the center section of the conductor 14, hereinafter referred to as the circuit board 14c.

[0024] To facilitate this, the conductor 14 (see also Fig. 1c) on both sides of the circuit board 14c has predetermined breaking points 14b in the form of notches. In addition, recesses or incisions 14d are provided at the end of the notches, so that not only the thickness of the conductor 14 in the area of ​​the predetermined breaking points 14b is reduced, but also its width. In this way, the circuit board 14c can be easily removed by the separating piston 19 (see Fig. 1a ) are punched out. The conductor 14 (see also Fig. 1c ) has holes 14a at its ends, allowing a cable to be screwed onto each end. As long as the conductor 14 remains intact, the two screwed-on cables are electrically connected. As soon as the circuit board 14c is punched out, they are electrically separated. In this way, very high voltages (e.g., 500 V) can be separated, even when very high currents (e.g., 2000 A) are flowing.

[0025] For the simplest possible production of the conductor overmolding 15, a central sprue 21 (see also Fig. 1b , 1d and 1e ) is provided, through which the liquid plastic is fed into the injection mold. It is distributed outwardly via an umbrella-shaped sprue distributor 22, where it forms the actual conductor overmolding 15. The transition between the sprue distributor 22 and the actual conductor overmolding 15 is referred to below as gate 23. The sprue 21 including the sprue distributor 22 can be separated at gate 23, which will be explained further below.

[0026] According to a preferred embodiment of the invention, the sprue 21 remains in the current separator 11. If the lower housing part 12 (see Fig. 1a) a corresponding recess 31 is provided, the combination of sprue 21 and recess 31 acts as a guide for the plate 14c while it is moved downwards by the separating piston 19, and with appropriately selected diameters, a relatively gentle braking of the plate 14c can also be achieved.

[0027] How to do this in particular Fig. 1d sees, the plastic of the conductor overmolding 15 fills the notches of the predetermined breaking points 14b on the side facing the sprue 21, whereby the conductor 14 is stabilized.

[0028] The execution according to the Fig. 2a and 2b differs from the embodiment just described in that four distribution channels 24a to 24d are provided instead of the umbrella-shaped sprue distributor 22. These distribution channels 24a to 24d each form an angle of approximately 45° with the longitudinal axis of the conductor 14, so that in the area of ​​the recesses 14d (see Fig. 1c) of the conductor 14. In this way, the sections 23 (see Fig. 2b ) at the level of the conductor or board 14c.

[0029] The execution according to the Fig. 3a and 3b differs from the execution according to Fig. 2a and 2b This is due solely to the fact that during injection molding, a filler space was present between the sprue 21 and the distribution channels 24a-24d, which is helpful for the even distribution of the plastic into the four distribution channels 24a-24d. The plastic remaining there is referred to as filler space plastic 25. It improves the connection between the sprue 21 and the blank 14c.

[0030] This connection can be further stabilized by drilling a central hole 14e in the board 14c (see Fig. 4b) is provided, through which the plastic passes during injection molding and forms a widening 27 behind it. In this way, a positive connection is even created between the sprue 21 and the plate 14c, so that the diameter of the filling space plastic 25' can be smaller than in the previously described embodiment according to the Fig. 3a and 3b .

[0031] In the Fig. 5a to 5c An embodiment is shown where two distribution channels 26a, 26b are provided. These two distribution channels 26a, 26b run perpendicular to the longitudinal axis of the conductor 14. Since the width of the conductor 14 is smaller than the diameter of the cavity 20, the cutouts 23 can be located at the height of the conductor 14 or the circuit board 14c. The area 28 between the conductor 14 and the conductor overmolding 15 can be free, but it can also be filled with plastic.

[0032] However, the cuts 23 can also be below, as shown in the Fig. 6a to 6c This embodiment differs from the embodiment just described in that the circuit board 14c has a central hole 14e, as in the embodiment according to Fig. 4b This is the case. However, the plastic does not extend into the area above the blank 14c, so that the sprue 21, including the filling chamber plastic 25' and the distribution channels 26a, 26b, can be easily separated at the gates 23 by pressing a stamper onto the hole 14e from above.

Claims

1. Method for producing a conductor (14) for a current breaker (11), the conductor comprising, between two conductor ends, a partition (14c) to be separated, wherein the conductor (14) comprises a conductor overmolding (15) having a cavity (20) in which the partition (14c) is arranged, wherein a plastic melt is injected via at least one sprue (21) into an injection mold in which the conductor (14) is located, characterized in that injection through the sprue (21) is performed from the cavity (20) penetrated by the conductor, and the plastic melt flows from the sprue (21) to the actual conductor overmolding (15) via a distributor (22; 24a-24d; 26a, 26b).

2. The method according to claim 1, characterized in that the sprue stub (21) together with the distributor stub (22; 24a-24d; 26a, 26b) is removed from the conductor overmolding (15) before installation into the housing of the current breaker (11).

3. The method according to claim 2, characterized in that the sprue stub (21) is separated, preferably punched off, from the conductor overmolding (15) in the injection molding tool.

4. The method according to claim 3, characterized in that the sprue stub (21) is separated or punched off by at least one ejector.

5. The method according to claim 2, characterized in that the conductor (14) has a hole (14e) and that the sprue stub (21) is separated by means of a punch which is guided through this hole (14e).

6. A conductor (14) with a conductor overmolding (15) produced according to claim 1, the conductor overmolding (15) comprising a cavity (20) in which the partition (14c) is located, and a sprue stub (21), characterized in that the sprue stub (21), including the distributor stub (22), is present in the cavity (20) of the conductor overmolding (15).

7. The conductor according to claim 6, characterized in that the distributor stub (22) is at least partially umbrella-shaped.

8. The conductor according to claim 6 or 7, characterized in that between the sprue stub (21) and the distributor stub (22; 24a-24d; 26a, 26b) there is a filling cavity stub (25, 25') which, compared to the sprue stub (21), extends further in the direction of the wall of the cavity (20).

9. The conductor according to one of claims 6 to 8, characterized in that the partition (14c) has a hole (14e) and at least a part of the sprue stub (21) extends through this hole (14e) and preferably has, behind the hole (14e), a larger cross-section than the cross-section of the hole (14e).

10. The conductor according to one of claims 6 to 9, characterized in that the distributor stub is formed by a plurality of channels (24a-24d), the connections of which to the conductor overmolding (15) being made in the lateral edge region of the conductor (14).

11. The conductor according to claim 10, characterized in that the connections of the channels (24a-24d) to the conductor overmolding (15) touch predetermined breaking points (14b) of the conductor (14).

12. The conductor according to one of claims 6 to 9, characterized in that the connections of the distributor (26a, 26b) to the conductor overmolding (15) are made in a plane which is spaced from the conductor (14), preferably at a distance of at least 1 mm, particularly preferably at least 2 mm.

13. The conductor according to claim 12, characterized in that the distributor comprises two distribution channels (26a, 26b) which are oriented perpendicular to the longitudinal axis of the conductor (14).

14. The conductor according to one of claims 6 to 13, characterized in that the conductor (14) has a cross-sectional reduction in the region of entry into the conductor overmolding (15).

15. A current breaker (11) comprising a housing, a pyrotechnic igniter (17) and a separating piston (19) for separating a partition (14c) from a conductor (14), characterized in that the conductor (14) with conductor overmolding (15) is formed according to one of claims 6 to 14.