CONTACT CARRIER, CONTACT CARRIER ARRANGEMENT AND LOW-VOLTAGE CIRCUIT BREAKER

Description

[0001] The invention relates to a contact carrier for fastening a contact element of a low-voltage protective switching device by means of a soldering process, such that a solder layer is formed between the contact carrier and the contact element. Furthermore, the invention relates to a contact carrier arrangement comprising a contact carrier and a contact element fastened thereto by soldering, as well as to a low-voltage protective switching device comprising such a contact carrier and / or such a contact carrier arrangement.

[0002] Electromechanical low-voltage protective devices, such as circuit breakers, miniature circuit breakers of various current classes such as MCBs (miniature circuit breakers), MCCBs (molded case circuit breakers), or ACBs (air circuit breakers), as well as industrial low-voltage protective devices such as motor protection switches, contactors, or soft starters, have at least one switching contact with which the circuit monitored by the respective low-voltage protective device can be interrupted when a predefined condition occurs, such as a short circuit or thermal overload. For this purpose, two contact elements of the switching contact are separated from each other, usually by moving a movable contact element away from a contact element fixed in the protective device's housing.The term "switching contact" includes both simple switching contacts with only one contact point and double-interrupting switching contacts, for example bridge contacts, in which the current flow at two contacts electrically connected in series is interrupted by means of a contact bridge on which two movable contact elements are arranged.

[0003] The actual contact element is usually made of a silver alloy due to its good electrical conductivity. However, since silver is both expensive and relatively soft, the contact carriers—the components to which the contact elements are attached and which must have a certain strength—are not made of silver, but of copper or steel. The term "contact carrier" refers to both a contact carrier that is fixed in a housing of the circuit breaker (so-called fixed contact carrier) and a contact carrier that can be moved within the housing (so-called moving contact carrier).

[0004] A soldering process, such as resistance soldering, is generally used to attach the mostly cuboid-shaped contact elements to the respective contact carrier in order to maintain good joint strength despite the lower joining temperature. This can cause the solder mass, which acts as an intermediate layer between the contact carrier and the contact element to bond with both joining partners and thus form a stable joint, to protrude laterally from beneath the contact element and rise up the sides of the contact element. Since this can negatively impact the process reliability of the joining process and the reliability of the joint – and thus the reliability of the low-voltage protective device – this so-called solder rise must be avoided or kept as low as possible.

[0005] From the document US 2 759 074 A, a contact carrier for fastening a contact element by means of a soldering process is known, so that a solder layer is formed between the contact carrier and the contact element, wherein the contact carrier has a contacting surface for the solder layer delimited by a first groove-like depression.

[0006] Furthermore, a generic contact carrier is known from the document US 2 298 999 A, in which the contacting surface additionally has a rough surface structure.

[0007] It is therefore the object of the present invention to provide a contact carrier, a contact carrier arrangement and a low-voltage protective switching device which avoids or at least reduces the above-mentioned problems.

[0008] This object is achieved according to the invention by the contact carrier, the contact carrier arrangement, and the low-voltage protective switching device according to the independent claims. Advantageous embodiments are the subject of the dependent claims.

[0009] The contact carrier according to the invention serves for fastening a contact element of a low-voltage protective switching device by means of a soldering process, so that a solder layer is formed between the contact carrier and the contact element, and has a contacting surface for the solder layer, which in turn has a rough surface structure and is delimited by a first groove-like depression.

[0010] Depending on the type of switch contact (single or double break switch contact), two contact elements can be arranged on one contact carrier. Regardless of the number of contact elements, when the contact element is joined to the contact carrier using resistance soldering, the underside of the contact element is usually first coated with solder. The underside of the contact element is then placed on the contact surface formed on the contact carrier and heated using an electric current. The rough surface structure, which can be created, for example, by rough planing or embossing, gives the contact surface a multitude of small depressions that serve as solder deposits into which the solder, which liquefies due to the heating, can flow.This causes a smaller amount of the liquid solder material to emerge from the sides of the contact element and rise up the contact element's sides. If solder rises up one or more of the contact element's sides, there is a risk that the solder will run onto the top of the contact element due to capillary action, which could lead to the failure of the low-voltage circuit breaker. Furthermore, rough planing increases the contact resistance between the contact element and the contact carrier.

[0011] The first groove-like depression, which defines the contacting surface and can also be produced by embossing, serves as an additional solder depot, i.e. as a receiving volume into which excess solder material can flow in order to prevent the solder material from rising up one or more of the side surfaces of the contact element. Furthermore, the bonding proportion of the solder connection, i.e. the proportion of the area connected by the solder connection, is significantly increased. In this way, the flow behavior of the solder material can be specifically influenced during the soldering process so that solder rise can be significantly reduced. The quality of the joint - and thus the process reliability of the joining process - is thereby significantly improved, which can significantly reduce the probability of failure of the low-voltage protective switchgear.

[0012] In the inventive design of the contact carrier, the contacting surface is substantially rectangular in shape and has a second groove-like depression which runs in a crescent shape from a first corner to an adjacent second corner of the rectangular contacting surface.

[0013] The second groove-like depression can be produced, for example, by embossing. With its help, it is possible to direct the solder flow, i.e. the liquefied solder material, from the center of the rectangular contact surface towards the corners – and thus into the first groove-like depression surrounding the contact surface. In this way, the solder rise, i.e. the rising of the solder material on the side surfaces of the contact element, can be significantly reduced. The geometry of the second groove-like depression can be adapted to the conditions of the respective contact carrier arrangement, i.e. to the interaction of a respective contact carrier with a respective contact element, by varying the crescent width and depth.

[0014] In a further advantageous development of the contact carrier, the contacting surface has a third groove-like depression, which runs in a crescent shape from a third corner to an adjacent fourth corner of the rectangular contacting surface. The effect of the second groove-like depression to limit solder rise is further enhanced by the third groove-like depression. The second and third groove-like depressions can be arranged symmetrically on the contacting surface.

[0015] In a further advantageous development of the contact carrier, the contacting surface is completely enclosed by the first groove-like depression. The contacting surface is circumferentially delimited by the first groove-like depression and thus enclosed without interruption, so that the leakage of solder material onto the surface of the contact carrier surrounding the first groove-like depression can be largely prevented. This further improves the process reliability of the joining process.

[0016] In a further advantageous embodiment, the contact carrier is made of sheet metal, in particular copper sheet metal. The use of copper sheet metal enables good electrical conductivity while simultaneously maintaining sufficient mechanical stability. The term "copper" encompasses both pure copper material and copper alloys. Furthermore, the term "sheet metal" refers to a component whose lateral and horizontal dimensions are significantly larger than its vertical dimensions, i.e., the component has a relatively small thickness or height compared to its length and width.

[0017] In a further advantageous development, the contact carrier has a rear-mounted indentation in the area of ​​the contacting surface. In the area of ​​the contacting surface, which is formed on a top side of the contact carrier, the contact carrier has an indentation on a bottom side of the contact carrier opposite the top side. In this way, the current flow—and thus the heating zone during resistance soldering—can be specifically influenced. Depending on the variant, the indentation on the bottom side of the contact carrier can be adapted to the respective conditions in terms of its size and contour.

[0018] The contact carrier arrangement according to the invention for a switching contact of a low-voltage protective switching device has a contact carrier of the type described above and a contact element fastened thereto by soldering, so that a solder layer is formed between the contact carrier and the contact element.

[0019] With regard to the general advantages of the contact carrier assembly according to the invention, reference is made to the above statements regarding the advantages of the contact carrier according to the invention. The phrase "by soldering" is to be understood as meaning that the contact element is firmly attached to the contact carrier using a soldering process, for example, the resistance soldering process.

[0020] In an advantageous development of the contact carrier arrangement, the contact element has a bulbous upper surface. A lower surface of the contact element faces the contact surface of the contact carrier and is connected to it by soldering. The upper surface of the contact element, opposite the lower surface, serves to make contact with another contact element of the switching contact and is convex for this purpose, i.e., curved upwards or outwards.

[0021] In a further advantageous development of the contact carrier arrangement, the contact element is made of a silver alloy. The use of a silver alloy for the contact element has the advantage that silver exhibits good electrical conductivity and the strength requirements of the contact element are negligible.

[0022] The low-voltage protective switching device according to the invention, for example a circuit breaker, motor protection switch or the like, has a contact carrier and / or a contact carrier arrangement of the type described above.

[0023] By using the contact carrier according to the invention and / or the contact carrier arrangement according to the invention, the quality of the joining connection - and thus the process reliability of the joining process - is significantly improved, whereby the probability of failure of the low-voltage protective switching device can be significantly reduced.

[0024] In the following, exemplary embodiments of the contact carrier and the contact carrier arrangement are explained in more detail with reference to the attached figures. The figures show: Figures 1 and 2 schematic representations of a contact carrier arrangement, without the crescent-shaped recess according to the invention; Figures 3 and 4 schematic representations of a contact carrier arrangement, without the crescent-shaped recess according to the invention; Figures 5 and 6 schematic representations of a contact carrier arrangement, without the crescent-shaped recess according to the invention; Figure 7 a schematic representation of a contact carrier arrangement, without the crescent-shaped recess according to the invention; Figure 8 a schematic representation of a contact carrier arrangement with the crescent-shaped recess according to the invention; Figures 9 and 10 schematic representations of a contact carrier arrangement, without or with the crescent-shaped recess according to the invention;

[0025] In the various figures of the drawing, identical parts are always provided with the same reference symbol. This description applies to all drawing figures in which the corresponding part can also be seen.

[0026] In the Figures 1 and 2 A contact carrier assembly 1 is shown schematically in plan and elevation views. The contact carrier assembly 1 has a contact carrier 10, on which a substantially cuboid-shaped contact element 20 is fastened. The contact element 20 is placed on a contact surface 13 provided for this purpose (see Figures 5ff) of the contact carrier 10 and is integrally connected by soldering, so that a flat solder layer 21 is formed between the contact surface 13 of the contact carrier 10 and the contact element 20.

[0027] The contact carrier 10 comprises electrically conductive material—for example, steel, copper, or a combination of both materials, for example, copper-plated steel sheet or copper electroplated onto steel sheet—and can be manufactured, for example, by stamping. The contact element 20 is preferably formed from a silver alloy. Since both the contact carrier 10 and the contact element 20 are electrically conductive, resistance soldering is preferably used as the soldering method for connecting the two joining partners—the contact element 20 and the contact carrier 10. To accommodate excess solder material, the contact carrier 10 further comprises a first groove-like recess 14, which delimits the contacting surface 13 to the outside.

[0028] In the Figures 3 and 4A contact carrier arrangement 1 is shown schematically in plan and elevation views. This is a so-called bridge contact with two switching points electrically connected in series, in which two contact elements 20 are accordingly attached to the movably mounted contact carrier 10 by soldering.

[0029] The contact element 20, which is shown as essentially cuboid-shaped, has a bottom side, via which it is connected to a top side 11 of the contact carrier 10. An upper side of the contact element 20 opposite the bottom side is shown in the illustrations of the Figures 1 to 4 as a flat surface oriented parallel to the top side 21. However, this is not absolutely necessary; it is also possible to design the top side of the contact element 20 to be spherical, i.e., curved upwards, i.e., convex.

[0030] In the Figures 5 to 10various design features are shown schematically in different views, however not always the inventive crescent-shaped recess of the inventive contact carrier 10. The Figures 5 and 6 show schematic representations of a contact carrier 10, where Figure 5 shows a plan view of the contact carrier 10, while in Figure 6 a sectional view along the Figure 5 shown schematically on the section line AA.

[0031] The contact carrier 10 has a sheet-like shape, i.e. its length and width in a first direction x and a second direction y are significantly greater than its thickness in a third direction z. The contact carrier 10 is made of an electrically conductive material and can be produced, for example, by stamping. The essentially rectangular contact surface 13 for contacting the contact element 20 is formed on the upper side 11 of the contact carrier 10. The contact surface 13 has a rough surface structure, which can be produced, for example, by embossing or rough planing, and is delimited by the first groove-like depression 14, which completely surrounds the contact surface 13.

[0032] In Figure 7 The contact carrier 10 is shown schematically. Figure 7 also a sectional view along the Figure 5The section line AA is drawn here. However, the contact carrier 10 shown here has an indentation 17 on its underside 12 opposite the top side 11, which is formed on the rear side in the area of ​​the contacting surface 13. With the help of the indentation 17, which can be adapted in terms of size and shape to the variant of a low-voltage protective switching device to be formed, the electrical current flowing through the contact carrier—and thus through the contact arrangement—during resistance soldering can be specifically influenced. In this way, the solder rise on the sides of the contact element 20 can be reduced.

[0033] In Figure 8 A third embodiment of the contact carrier 10 according to the invention is shown schematically. The representation of the contact carrier 10 essentially corresponds to the representation described above for Figure 5, wherein the contact carrier 10 has a second groove-like depression 15 and a third groove-like depression 16 in the region of the rectangular contact surface 13. The two groove-like depressions 15 and 16 are arranged symmetrically to one another and each run in a crescent shape from one corner to an adjacent corner of the rectangular contact surface 13, each spanning one of the long sides of the rectangular contact surface 13.

[0034] The second and third groove-shaped depressions can also be produced by embossing or rough planing and serve to direct the solder flow away from the sides and towards the corners of the contacting surface 13 in order to prevent or at least reduce solder rise on the sides of the contact element 20. The width and curvature of the two crescent-shaped groove-like depressions 15 and 16, respectively, can be adapted to the respective switching device type in terms of their size and contour. Figure 8 The embodiment shown is available with or without back embossing according to the illustrations of the Figures 6 and 7 feasible.

[0035] In the presentation of the Figure 8 The contacting surface 13 has a first and a second groove-like depression; however, it is also possible to provide the contacting surface 13 with only one of the two crescent-shaped, groove-like depressions 15 and 16, respectively.

[0036] The Figures 9 and 10 show schematically further features of the contact carrier 10 according to the Figures 3 and 4 already known design as a bridge contact in plan view, ie with a view of the top side 11 of the contact carrier 10. Figure 9 shows the contact carrier 10 designed as a bridge contact with two contact surfaces 13, each surrounded by a first groove-like depression 14. The underside 12 (see Figures 6 and 7 ) can be designed with or without indentation 17. In Figure 10 is the contact carrier 10 designed as a bridge contact, wherein the two contact surfaces 13 each have, in addition to the first groove-like recess 14, the two crescent-shaped groove-like recesses 15 and 16. Here, too, the underside 12 can be designed with or without an indentation 17.

[0037] The design measures described above, i.e., the rough surface structure of the contacting surface 13, the first groove-like recess 14, and the two crescent-shaped groove-like recesses 15 and 16, significantly reduce solder rise. The geometric design of these design measures can be adapted to the specific conditions of the respective switching device type, depending on the contact size, contact material, dimensions of the contact carrier, etc. List of reference symbols

[0038] 1Contact carrier arrangement 10Contact carrier 11Top side 12Bottom side 13Contacting surface 14First groove-like depression 15Second groove-like depression 16Third groove-like depression 17Impression 20Contact element 21Solder layer Xfirst direction Ysecond direction Zthird direction

Claims

1. Contact carrier (10) for fastening a contact element (20) of a low-voltage protective switching device by means of a soldering operation, so that a solder layer (21) is formed between the contact carrier (10) and the contact element (20), wherein the contact carrier (10) has a contacting area (13) for the solder layer (21), wherein the contacting area (13) has a rough surface structure and is delimited by a first channel-like depression (14), characterized in that the contacting area (13) is of substantially rectangular shape and has a second channel-like depression (15) which runs in the shape of a sickle from a first corner to an adjacent second corner of the rectangular contacting area (13).

2. Contact carrier (10) according to Claim 1, wherein the contacting area (13) has a third channel-like depression (16) which runs in the shape of a sickle from a third corner to an adjacent fourth corner of the rectangular contacting area (13).

3. Contact carrier (10) according to either of the preceding claims, wherein the contacting area (13) is completely surrounded by the first channel-like depression (14).

4. Contact carrier (10) according to any of the preceding claims, wherein the contact carrier (10) is formed from sheet metal, in particular from sheet copper.

5. Contact carrier (10) according to any of the preceding claims, wherein the contact carrier (10) has a rear-side impression (17) in the region of the contacting area (13).

6. Contact-carrier arrangement (1) for a switching contact of a low-voltage protective switching device, having a contact carrier (10) formed according to any of Claims 1 to 5 and a contact element (20) fastened to the contact carrier by means of soldering, so that a solder layer (21) is formed between the contact carrier (10) and the contact element (20).

7. Contact carrier arrangement (1) according to Claim 6, wherein the contact element (20) has a convex top side.

8. Contact carrier arrangement (1) according to either of Claims 6 and 7, wherein the contact element (20) is formed from a silver alloy.

9. Low-voltage protective switching device, for example line circuit breaker, motor circuit breaker or the like, which has a contact carrier (10) according to any of Claims 1 to 5 and / or a contact-carrier arrangement (1) according to either of Claims 7 and 8.