Current discharge element

Abstract

Current diverting element, comprising a carrier (2) with a bore (6) and a contact element (7) resting on a shaft (17) which, in the assembled position, passes through the bore (6) and projects into the bore (6), wherein the carrier (2) has at least one opening (11) for receiving a connecting element (18) for connection to a third object, and wherein at least one diverting wire (13) is provided which, on the one hand, is in contact with the contact element (7) and, on the other hand, is guided into the region of the opening (11) for contact with the connecting element (18), and wherein the contact element (7) is annular and is fixed to the carrier (2) by means of an annular retaining disk (9), and wherein the or each diverting wire (13) is clamped between the contact element (7) and the retaining disk (9).

Description

[0001] In rotating mechanical systems, electrical currents can sometimes arise that must be dissipated to prevent any damage, meaning that a potentially live component must be earthed. DE 2 308 936 A, for example, discloses a conceivable current-dissipating element for the axle bearings of rail vehicles. Another example of this is high-voltage drives for motor vehicles, so-called e-axles comprising an electric motor drive with an associated gearbox, in which the electric motor drive is operated with voltages of several hundred V. For earthing, it is known to use sliding contacts or brush contacts, as shown in DE 10 2016 209 627 A1 for a synchronous motor, wherein the respective contact is connected to a rotating shaft and is otherwise earthed.It is also known to provide grounding via a bearing on which a shaft is rotatably mounted. A contact element is integrated into the bearing, which sits in sliding contact with the shaft and through which the current is diverted. However, such a bearing with such an integrated shunt function is complex in its design and must be specifically tailored to the application.

[0002] The invention is based on the problem of providing an improved current discharge element.

[0003] To solve the problem, the invention proposes a current diverting element comprising a carrier with a bore and a contact element which bears against a shaft which, in the assembled position, passes through the bore and projects into the bore, wherein the carrier has at least one opening for receiving a connecting element for connection to a third object, and wherein at least one diverting wire is provided which, on the one hand, is in contact with the contact element and, on the other hand, is guided into the region of the opening for contact with the connecting element.

[0004] The current diverting element according to the invention is a separate component that, on the one hand, accommodates the shaft and, on the other hand, is directly connected to a housing component. The current diverting element comprises a substantially plate-shaped carrier with a bore and a contact element projecting into the bore, i.e., the actual shunt element, which is in contact with a shaft passing through the bore, thus sliding against it. The carrier, in turn, i.e., ultimately the current diverting element itself, is directly connected to a third object, such as a housing component, for which purpose at least one opening is provided on the carrier for receiving a connecting element, such as a connecting screw for connecting the current diverting element to the third object, i.e., the transmission housing component. The connecting screw thus fixes the current diverting element in the assembly position.In order to discharge current, there must be an electrically conductive connection between the shaft and the housing component through which the earthing is established. Part of this connection is the contact element, which is in electrical contact with the shaft. At least one discharge wire is in contact with this contact element, which serves for the electrical connection to the connecting element in the assembled position, e.g. the screw, which in turn is in electrical contact with a third object such as the housing component. For this purpose, the discharge wire is guided into the area of ​​the opening to make contact with the connecting element. If the connecting element is inserted, e.g. the connecting screw is screwed in, contact is automatically established between the connecting screw and the discharge wire.This creates an electrical path between the shaft and the third object, formed by the contact element, the discharge wire, and the connecting element. The wire can either be glued to the carrier, or additionally or alternatively, it can also be mechanically fixed.

[0005] The contact element itself is ring-shaped and fixed to the carrier by means of an annular retaining disc. Such a contact element is also called a circular blank and its cross-section is designed such that its inner circumference rubs against the shaft and is centered by this. The contact surface is designed to provide an optimal compromise between sufficient contact and not excessive grinding stress. A retaining disc serves as a simple means of fixation, with the annular contact element, i.e., the circular blank, being braced or clamped between the retaining disc and the carrier. The or each discharge wire is clamped between the contact element and the retaining disc.

[0006] The formation of the earth connection via the discharge wire makes it possible to manufacture the carrier from plastic, i.e. a material that is non-conductive or only extremely poorly conductive. This is because the electrical contact to earth is achieved via the electrically conductive discharge wire, for example a copper wire, i.e. the carrier itself is not integrated into the discharge path. Manufacturing the carrier from plastic makes production very simple and cost-effective, and the carrier can be manufactured in virtually any shape. Alternatively, the carrier can of course also be made from metal, preferably from a stamped and possibly formed metal sheet. This is of course conductive itself, but depending on the material, its conductivity can be lower than that of a discharge wire, for example a copper wire. This means thatThe electrical resistance of the metal carrier is higher than that of the drain wire, allowing for improved grounding and thus better current dissipation via the drain wire. In such a case, the connecting element, such as the connecting screw, must be made of a suitable, low-resistance material similar to the drain wire or provided with a suitable low-resistance coating.

[0007] According to an advantageous development of the invention, the discharge wire can be laid in the region of the opening in the manner of a loop, such that a head of the connecting element is in contact with the discharge wire in the assembled position. The discharge wire is thus guided around the opening in a loop-like or loop-like manner, running relatively close to the edge of the opening. When the connecting element, e.g., the connecting screw, is screwed in, the head automatically runs axially onto the discharge wire upon reaching the end position. The wire is firmly clamped between the head and the carrier, thereby inevitably making electrical contact with the connecting element. This creates an automatic ground connection during assembly.

[0008] According to the invention, it can further be provided that the carrier has at least two openings, wherein either only one opening is assigned a discharge wire, or wherein both openings are each assigned a discharge wire or a common discharge wire. Accordingly, the carrier is fastened in two different positions by means of two connecting elements or connecting screws, which provides even better fastening, combined with an anti-twist device. For grounding, it is sufficient if only one discharge wire is provided, which runs from the contact element into the region of one opening. For redundancy reasons, a second discharge wire can also be provided, which runs from the contact element to the other opening, so that grounding is also possible via this path. Finally, a third alternative provides a common discharge wire that runs from one opening via the contact element to the other opening.Different contact options are therefore possible.

[0009] With regard to the actual laying of the discharge wire(s), different designs are conceivable. According to a first variant, the or each discharge wire can have two ends with which it is in contact with the contact element. The discharge wire is therefore an elongated wire that is in contact with the contact element at both ends and runs to the connecting element and from there back again. The individual discharge wire is therefore laid as a loop over its entire length. Alternatively, according to a second variant, it is conceivable for a common discharge wire to be designed as a closed ring that is led from one opening to the other and, in sections, along and in contact with the contact element. According to this variant, only one closed, i.e. endless, discharge wire is provided, which runs from one opening to the other and is preferably looped around the opening.One or both lengths running between the openings are guided along the contact element and are in contact with it.

[0010] According to a further development of the invention, one or more stiffening ribs formed by groove-like depressions can be provided on the support. The torsional rigidity of the quasi-plate-shaped support can be increased by means of these one or more such stiffening ribs, thus making it more torsionally rigid. Such a stiffening rib can be formed directly during the manufacture of the support, for example, in the case of a support made of metal, it can be molded in during punching and forming. In the case of a support made of plastic, such a stiffening rib can already be defined directly via the injection mold. According to the invention, the discharge wire can be guided at least sectionally in one or more depressions. The groove-like depressions therefore serve as guides for the discharge wire, whereby, if several discharge wires are provided, both can of course be guided sectionally in corresponding depressions.

[0011] One or more lead-through openings can be provided on the support, through which the discharge wire runs from one side of the support to the other. If the discharge wire contacts the contact element or the connecting element on one side of the support, and the groove-like recesses are located on the other side of the support, so that the stiffening ribs protrude toward the side with the discharge wire contacts, the or each discharge wire can be routed via lead-through openings from the contact side to the opposite side, inserted into the groove-like recesses there, and then routed back to the contact side via another lead-through opening.

[0012] The carrier can have an annular, recessed receptacle for the contact element, with the retaining disc radially overlapping the contact element. This recessed, i.e., axially flared receptacle, which is also formed, for example, by partial deep drawing during sheet metal forming or directly during plastic injection molding, can create an additional axial offset between the plane of the annular contact element and the mounting plane on the housing side.

[0013] The retaining disc is preferably fastened to the carrier via a plurality of retaining elements formed on the carrier, each passing through an opening in the retaining disc.

[0014] These retaining elements are advantageously made integrally with the support. The retaining elements can, for example, be designed as axially projecting pins that extend through the openings and are caulked or cupped to the free, extending end. Direct locking without separate forming is also conceivable.

[0015] The invention is explained below using exemplary embodiments with reference to the drawings. The drawings are schematic representations and show: Fig. 1 a schematic diagram of a current discharge element according to the invention of a first embodiment in a perspective view, Fig. 2 a schematic diagram of the current discharge element from Fig. 1 in the assembly position, Fig. 3 a schematic diagram of a current discharge element according to the invention of a second embodiment in a sectional view, and Fig. 4 an enlarged view of the connection area of ​​the retaining disc with the carrier.

[0016] Fig. 1 shows a current collector element 1 according to the invention, comprising a carrier 2, which in the example shown is made of plastic and is manufactured using a mold in an injection molding process. It is therefore made of a material that is non-conductive or very poorly electrically conductive. The carrier 2 has the central, middle carrier section 3 and two lateral, projecting sections 4. The carrier 2 can be stiffened by means of stiffening ribs 5, which are projected out on the other side via groove-like depressions made on one side, so that it becomes more torsionally rigid. The central carrier section 3 has a bore 6, into which an annular contact element 7, fastened to the carrier 3, projects with its inner circumference 8, which serves as a sliding contact for a shaft passing through the bore 6. The annular contact element 7, also made of metal, is held or secured by an annular retaining disk 9, which is fixed to the carrier 3 via suitable connecting means 10.clamped between the retaining disc 9 and the carrier 3. The retaining disc 9 is preferably also made of metal.

[0017] The two protruding sections 4 each have an opening 11, which in the example shown is also cylindrical. Each opening 11 is followed by a spacer element 12 in the form of a separate spacer sleeve. Each spacer element 12 can also be made of plastic, but also of ceramic or metal. In the assembled position, the carrier 3 is supported on a third object, for example a housing component, via the two spacer elements 12. In the assembled position, connecting screws engage through the openings 11 and are screwed into corresponding threaded holes on the housing component, via which the current discharge element 1 is fixed. The spacer elements 12 are therefore separate elements in this example. Any currents present at the shaft (not shown in detail) are discharged via the current discharge element 1 directly into the housing component, since the shaft is electrically contacted via the contact element 6, i.e. the round plate.In order to conduct the current from the contact element 7, the example shown features a metal discharge wire 13, made of copper for example, which is designed as a closed loop. It extends from one opening 11 to the other opening 11, encircling the respective opening to form a loop 14. Via feedthrough openings 15, which are preferably already made in the carrier during its manufacture, the discharge wire 13 can be guided from the edge of the opening 11 to the opposite side, where it runs into a groove-like depression over which the reinforcing ribs 5 projecting on the opposite side, i.e. the actual contact side, are formed. This is where the wire is guided in a defined manner. Via further feedthrough openings 15, the discharge wire is again led to the loop 14 shown in FIG. Fig. 1 and runs under the retaining disc 9, being clamped between the retaining disc 9 and the contact element 7. The course below the retaining disc 9 is shown in dashed lines. It extends to the opposite section 4, where it runs out again below the retaining disc 9 and runs again via feedthrough openings 15 to the opposite side into groove-like recesses provided there, from which side it again leads to the Fig. 1 and wraps around the opposite opening 11. The discharge wire can be connected to the Fig. 1 shown side, for example, using an adhesive, and on the opposite side using the receptacle in the groove-like recesses or also using an adhesive.

[0018] Fig. 2 shows the current discharge element 1 according to the invention from Fig. 1 in the assembled position on a third object 16, for example a housing component. The current diverting element 1 is supported on the third object 16 by means of the two spacer elements 12, i.e. the spacer sleeves, or is spaced apart from it in a defined manner, such that the contact element is positioned in a defined axial position relative to a shaft 17 passing through the bore 6, for example a gear shaft. To fasten the current diverting element 1, two connecting elements 18 in the form of connecting screws 19 are provided, which are screwed into corresponding threaded holes on the third object. Each connecting element 19 has a head 20, which rests firmly on the loop 14 of the diverter wire 13, either directly or via an intermediate metal washer, i.e. the loop 14 is clamped between the head 20 and the carrier 2.This is how the electrical contact is made between the discharge wire 13 and the connecting elements 19 and via these to the third object 16, via which the earthing is carried out.

[0019] In the illustrated embodiment, the carrier 2 is made of plastic, which is why the basic conductivity or electrical connection between the contact element 7 and the third object 16 is achieved via the connecting elements 19 and the discharge wire 13. Nevertheless, the carrier 2 can also be made of metal or metal sheet. This can also serve as a discharge element because it is electrically conductive; however, the conductivity of such a metal sheet is sometimes poorer than that of a discharge wire made of copper, for example. The electrical conductivity can be improved if, despite the carrier 2 being made of metal, a corresponding discharge wire 13 is used that has a lower resistance than the metal carrier 2.

[0020] Fig. 3 shows an alternative embodiment of a current diverting element 1 according to the invention, wherein the same reference numerals are used for the same components. Here, too, a carrier 2 is provided, with the central carrier section 3 and the two lateral sections 4, as well as an annular contact element 7 with the inner circumference 8 forming the sliding contact and the retaining disk 9, which clamps the contact element 7 to the carrier 2. The two openings 12 are also provided on the two sections 4. Instead of the separate spacer elements 12 in the form of spacer sleeves, however, hollow-cylindrical spacer projections 21 in the form of sleeves 22 are integrally formed on the carrier. Here, the spacer projections 21 are therefore formed integrally with the carrier 2.In this example, the carrier 2 is also made of plastic, i.e., it is a plastic component that was manufactured in a corresponding shape by injection molding. This means that no direct electrical contact can be established between the metal contact element 7 and the transmission housing component via the carrier 2.

[0021] In order to electrically connect the contact element 6 to the housing component and to divert currents, a discharge wire 13 is provided in the example shown, which is laid as a closed ring on the plastic carrier 2 and is guided as a loop 14 around the respective opening 11. It also runs, more or less hidden, between the retaining disc 9 and the contact element 7, so that contact is established there between the contact element 7 and the discharge wire 13. The course of the discharge wire 13 below the retaining disc 9 is also indicated here by dashed lines. The alternating course of the discharge wire 13 between the two sides of the carrier 2 is also provided in this example.

[0022] As described, such an integral spacer projection 21 is also provided on the other opening 11, which can also be designed as a hollow cylindrical sleeve 22. If several integral spacer projections are provided, they can have the same geometry, but they can also differ in geometry. For example, the spacer projections can have the same shape, i.e., both be hollow cylindrical, but they can also differ in shape. Likewise, the spacer projections can have the same length, but they can also be different lengths. The concrete specific geometry of the spacer projections depends in particular on the installation space situation and the assembly conditions on the transmission housing component. In fact, no spacer projection can be provided on the second opening if the assembly conditions do not require one.

[0023] During assembly, i.e., when the connecting elements or connecting screws are inserted into the openings 11 and secured, the head 20 also rests on the respective loop 14, thus being in electrical contact with it. This means that the electrical contact is also established here from the contact element 7 via the discharge wire 13 and the respective connecting element to the housing component.

[0024] As an alternative to the plastic design of the support 2, a metal design is also conceivable for this form of support 2 with the integrally formed spacer projections 21. In this case, the spacer projections 21 would be formed directly during the punching and forming of the metal sheet to produce the support 2 in the form of through-holes.

[0025] Fig.Figure 4 shows an enlarged view of the area where the retaining disc 9 is connected to the carrier 2, which is provided in each of the embodiments described above. A recessed receptacle 23 is formed on the carrier 3, into which the annular contact element 7 is inserted. Also shown is the retaining disc 9, which is captively secured to the carrier 3 via the connecting means 10 and which evidently engages over the contact element 9 at the outer circumference and clamps it in a quasi-positive manner toward the carrier 3 or the recessed receptacle 23. Axially projecting pins 24 are formed on the carrier 3, which penetrate respective openings 25 in the retaining disc 9 during assembly, after which the free end of the pins 24 is reshaped, for example, caulked, resulting in a corresponding retaining head 26 that engages over the retaining disc 9 and captively secures it. List of reference symbols 1 current discharge element 2 carriers 3 support section Section 4 5 stiffening rib 6 Hole 7 Contact element 8 inner circumference 9 Retaining disc 10 connecting devices 11 Breakthrough 12 spacer element 13 Drain wire 14 Loop 15 Feedthrough breakthrough 16 Third party object 17 Wave 18 Connecting element 19 Connecting screw 20 heads 21 distance advantage 22 sleeve 23 Recording 24 cones 25 Breakthrough 26 Holding head

Claims

[1] Current diverting element, comprising a carrier (2) with a bore (6) and a contact element (7) resting on a shaft (17) which, in the assembled position, passes through the bore (6) and projects into the bore (6), wherein the carrier (2) has at least one opening (11) for receiving a connecting element (18) for connection to a third object, and wherein at least one diverting wire (13) is provided which, on the one hand, is in contact with the contact element (7) and, on the other hand, is guided into the region of the opening (11) for contact with the connecting element (18), and wherein the contact element (7) is annular and is fixed to the carrier (2) by means of an annular retaining disk (9), and wherein the or each diverting wire (13) is clamped between the contact element (7) and the retaining disk (9). [2] Current discharge element according to claim 1, characterized bythat the discharge wire (13) is laid in the manner of a loop (14) in the region of the opening (11), such that a head (20) of the connecting element (18) is in contact with the discharge wire (13) in the assembly position. [3] Current discharge element according to claim 1 or 2, characterized by in that the carrier has at least two openings (11), wherein either only one opening (11) is assigned a discharge wire (13), or wherein both openings (11) are each assigned a discharge wire (13) or a common discharge wire (13). [4] Current discharge element according to claim 2 or 3, characterized by that the or each discharge wire (13) has two ends with which it is in contact with the contact element (7), or that a common discharge wire (13) is designed as a closed ring which is guided in sections from one opening (11) to the other along and in contact with the contact element (7). [5] Current diverting element according to one of the preceding claims, characterized by that one or more stiffening ribs (5) formed by groove-like depressions are provided on the support (2), wherein the discharge wire (13) is guided at least in sections in one or more depressions. [6] Current discharge element according to claim 5, characterized by that one or more feedthrough openings (15) through which the discharge wire (13) runs from one side of the carrier (2) to the other are provided on the carrier. [7] Current discharge element according to claim 1, characterized by that an annular, recessed receptacle (23) for the contact element (7) is formed on the carrier (2), wherein the contact element (7) is radially overlapped by the retaining disc (9). [8] Current discharge element according to one of claims 1 to 7, characterized bythat the retaining disc (9) is fastened to the carrier (2) via a plurality of retaining elements (24) formed on the carrier (2), each passing through an opening (25) in the retaining disc (9).

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