Current discharge element

Abstract

Current diverting element, comprising a carrier (2) with a bore (5) and a contact element (6) which bears against a shaft which, in the assembled position, passes through the bore (5) and projects into the bore (5), wherein the carrier (2) has at least one opening (10) for receiving a connecting element for connection to a third object, wherein the carrier (2) has an axially projecting spacer projection (11) in the region of the opening (10), and wherein the contact element (6) is annular and is fixed to the carrier (2) by means of an annular retaining disk (8), and wherein an annular, recessed receptacle (13) for the contact element (6) is formed on the carrier (2), wherein the contact element (6) is radially engaged over by the retaining disk (8).

Description

[0001] The invention relates to a current discharge element.

[0002] In rotating mechanical systems, electrical currents can sometimes arise which must be dissipated to avoid any damage, i.e. earthing of any potentially live component must be provided. One 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 100 V. For earthing, it is known to use sliding contacts or brush contacts, whereby the respective contact is connected to a rotating shaft and is otherwise earthed. It is also known to implement earthing via a bearing, via which a shaft is rotatably mounted, by integrating a contact element into the bearing which sits in sliding contact on the shaft and via which the current is discharged, as also disclosed in US 2002 / 0 190 598 A1.DE 10 2021 210 016 A1, for example, also shows such a bearing with an integrated shunt function, which, however, is complex in its design and must be specifically designed for the application.

[0003] The invention is based on the problem of providing an improved current discharge element.

[0004] 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, wherein the carrier has an axially projecting spacer projection in the region of the opening.

[0005] 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 engaging it in a sliding manner. The carrier, in turn, i.e., ultimately the current diverting element itself, is directly connected to 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 a third object, for example, the transmission housing component. The current diverting element is thus fixed in the assembly position via the connecting screw.To define the axial position of the contact element, the current diverting element is characterized by a spacer projection provided on the carrier, which projects axially in the area of ​​the opening. This spacer projection is used to adjust the distance between the quasi-plate-shaped carrier and the contact element and the fastening plane on the third object, such as the gearbox housing component. This spacer projection is therefore an integral part of the carrier and is formed as a single piece. This spacer projection ensures the precise axial positioning of the carrier and thus also of the contact element in the assembled position. Since the spacer projection is an integral part of the carrier, no additional separate spacer elements, such as spacer sleeves, are required, which are cumbersome to handle during assembly.

[0006] 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 centers itself there. The contact surface is designed to provide an optimal compromise between sufficient contact and minimal abrasive stress. A retaining disc serves as a simple means of fixation, with the annular contact element, i.e., the circular blank, being clamped or clamped between the retaining disc and the carrier.

[0007] The carrier has a ring-shaped, 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 ring-shaped contact element and the mounting plane on the housing side.

[0008] Preferably, the spacer projection is hollow-cylindrical and surrounds the opening. The spacer projection is therefore sleeve-like and essentially axially extends the opening, which accommodates the connecting element, for example, the connecting screw. The end face of the spacer projection or the hollow-cylindrical spacer projection rests axially against the end face of the third object or the transmission housing component and is clamped against it via the connecting element.

[0009] According to a first alternative, the support is made of metal, with the spacer projection being designed as a through-hole. The support is therefore inherently made of metal or sheet metal; it can be formed according to its required geometry during a forming and punching process, for example, by punching and forming it from a sheet metal blank. During this forming process, the spacer projection can be formed directly, regardless of the specific geometry of the spacer projection—for example, whether it is designed as a semicircular projection, a closed hollow cylindrical projection, or something similar. The spacer projection can therefore be formed through a simple forming process.The design of the carrier made of metal is particularly advantageous in that simply by contacting the metal carrier, which is electrically contacted by the contact element, with the gearbox housing component via the spacer projection, the electrical contact to the earthed gearbox is established, so that a closed electrical path is provided through which the current can be discharged.

[0010] As an alternative to making the carrier out of metal, it is also conceivable to manufacture the carrier out of plastic and to mold the spacer projection into it as a single piece during the manufacturing process. Such a carrier made of plastic can be easily produced using an injection molding process and can have a variety of geometries. This manufacturing process using an injection mold also allows for the molding of a corresponding spacer projection of any geometry, including hollow cylinders. If a plastic carrier is used, appropriate discharge means must of course be provided to ensure the electrical connection between the contact element and the grounded third-party object or device.Gearbox housing component, for example in the form of an electrically conductive coating, for example in the manner of a conductor track or similar, on the plastic carrier or a separate discharge wire or similar attached to the carrier, wherein these discharge means are guided, for example, to the opening where, during assembly, automatic contact of the connecting element to the discharge means and via this to the third object is achieved.

[0011] Preferably, the carrier has at least two openings, each with an associated spacer projection, which enables a more stable attachment to the transmission housing component, which is also secured against rotation. Each opening is assigned a separate spacer projection, if necessary.

[0012] If multiple 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, for example, both hollow cylindrical, but they can also differ in shape. Likewise, the spacer elements can have the same length, but they can also be different lengths. The specific geometry of the projections depends in particular on the available space and the assembly conditions on the transmission housing component.

[0013] According to a further development of the invention, one or more stiffening ribs formed by groove-like recesses can be provided on the support. These one or more stiffening ribs can increase the torsional rigidity of the quasi-plate-shaped support, 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.

[0014] The retaining disc is preferably secured to the carrier via several retaining elements formed on the carrier, each penetrating an opening in the retaining disc. These retaining elements are expediently designed as a single piece with the carrier. The retaining elements can, for example, be designed as axially projecting pins that penetrate the openings and are caulked or cupped to the free, penetrating 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 partial view, sectioned, of the current discharge element from Fig. 1, Fig. 3 an enlarged view of area III from Fig. 2, and Fig. 4 a sectional perspective view of a current discharge element according to the invention of a second embodiment.

[0016] Fig. 1 shows a current collector element 1 according to the invention, consisting of a carrier 2, which in the example shown is made of metal and is manufactured from a metal sheet. 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 20, which are projected on the other side via groove-like recesses introduced on one side, so that it becomes more torsionally rigid. The central carrier section 3 has a bore 5 into which an annular contact element 6, fastened to the carrier 3, projects with its inner circumference 7, which serves as a sliding contact for a shaft passing through the bore 5. The annular contact element 6, also made of metal, is held by an annular retaining disk 8, which is fixed to the carrier 3 via suitable connecting means 9, or is clamped between the retaining disk 8 and the carrier 3. The retaining disk 8 is preferably also made of metal.

[0017] The two projecting sections 4 each have an opening 10, which in the example shown is also cylindrical. Each opening 10 is followed by a spacer projection 11, whereby Fig. 1 only one of them is visible. In the design of the support 3 from a metal sheet, each spacer projection 10 is designed as a one-piece through-hole. In the example shown, the spacer projection 11 forms a hollow cylindrical spacer sleeve 12. In the assembled position, the support 3 is supported on a third object, for example a housing component, via the two spacer projections 11. In the assembled position, connecting screws engage through the openings 10 and are screwed into corresponding threaded holes on the third object or on the housing component, via which the current diverting element 1 is fixed. The spacer projections 11 are therefore designed as integral through-holes in this design, i.e. separate spacer elements are not required in this case.Any currents present on the shaft (not shown in detail) are diverted via the current diverting element 1 directly into the third object, since the shaft is electrically contacted via the contact element 6, i.e. the round plate, wherein the contact element 6 is in turn electrically connected to the carrier 3, which in turn is electrically connected directly to the earthed third object via the spacer projections 11 and, of course, also the connecting screw.

[0018] Fig. 2 shows an enlarged partial view of the current discharge element 1 from Fig. 1. The contact element 6 is shown with its offset inner circumference 7, which forms the sliding contact area. A recessed receptacle 13 is formed on the carrier 3, into which the annular contact element 6 is inserted. Also shown is the retaining disc 8, which is captively fixed to the carrier 3 via the connecting means 9 and which clearly overlaps the contact element 6 at the outer circumference, clamping it in a form-fitting manner to the carrier 3 or the recessed receptacle 13.

[0019] Also shown is the spacer projection 11 in the form of the spacer sleeve 12, which is formed in one piece, i.e. integrally, on the carrier 3 as a through-hole.

[0020] As described, a similar spacer projection 11 is also provided at the other opening 10. This spacer projection can also be designed as a hollow cylindrical spacer sleeve 12, but can also have a different geometry, for example, as a half-cylinder, and can also be longer or shorter. The specific geometry of the respective spacer projection depends on the specific installation situation. In fact, no spacer projection can be provided at the second opening if the installation conditions do not require one.

[0021] Fig. 3 shows an enlarged view of area III from Fig. 2 in the area of ​​the connection of the retaining disc 8 to the carrier 3. Axially projecting pins 14 are formed on the carrier 3, which engage through respective openings 15 in the retaining disc 8 during assembly, after which the free end of the pins 14 is reshaped, for example caulked, so that a corresponding holding head 16 is produced, which engages over the retaining disc 8 so that it is fixed captive.

[0022] In the assembled position, as described, the contact element 6 rests against the shaft with its inner circumference, meaning that electrical contact is established on this side. The metal contact element 6 is electrically connected to the metal carrier 3, which in turn is electrically connected to the grounded transmission component via the spacer projection, and additionally to the metal connecting screw. A corresponding current flow from the shaft to the transmission component is therefore possible.

[0023] Fig.4 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 6 with the inner circumference 7 forming the sliding contact and the holding disk 8, which clamps the contact element 6 to the carrier 2. The two openings 10 are also provided on the two sections 4, wherein an axially projecting spacer projection 11 in the form of a hollow cylindrical sleeve 12 is also provided there. Here, too, the spacer projection 11 is formed integrally with the carrier 2. In this example, however, the carrier 2 is made of plastic, i.e. it is a plastic component that was produced in a corresponding shape by injection molding. I.e.that no direct electrical contact can be achieved between the metal contact element 6 and the gear housing component via the carrier 2.

[0024] In order to electrically connect the contact element 6 to the housing component and to divert currents, the example shown provides a discharge means 17 in the form of a discharge wire 18, which is laid as a closed ring on the plastic carrier 2 and guided as a loop 19 around the respective opening 10. It also runs virtually hidden between the retaining disc 8 and the contact element 6, ensuring contact between the contact element 6 and the discharge wire 18. The course of the discharge wire 18 below the retaining disc 8 is indicated by dashed lines.

[0025] During assembly, i.e., when the connecting screws are inserted into the openings 10 and tightened, the screw head rests on the respective loop 19, thus making electrical contact with it. This means that the electrical contact here is established from the contact element 6 via the discharge wire 18 and the respective connecting screw to the housing component.

[0026] Even if the carrier 2 is made of metal, the use of such a discharge wire may be expedient, namely if the discharge wire has a lower resistance than the material of the carrier 2. In this case, connecting screws provided with a low-resistance coating on the outside can be used. List of reference symbols 1 current discharge element 2 carriers 3 support section Section 4 5 Hole 6 Contact element 7 inner circumference 8 retaining disc 9 connecting devices 10 Breakthrough 11 Distance advantage 12 spacer sleeve 13 Recording 14 cones 15 Breakthrough 16 Holding head 17 Discharge agents 18 Drain wire 19 Loop 20 stiffening rib III Area

Claims

[1] Current diverting element, comprising a carrier (2) with a bore (5) and a contact element (6) which bears against a shaft which, in the assembled position, passes through the bore (5) and projects into the bore (5), wherein the carrier (2) has at least one opening (10) for receiving a connecting element for connection to a third object, wherein the carrier (2) has an axially projecting spacer projection (11) in the region of the opening (10), and wherein the contact element (6) is annular and is fixed to the carrier (2) by means of an annular retaining disc (8), and wherein an annular, recessed receptacle (13) for the contact element (6) is formed on the carrier (2), wherein the contact element (6) is radially engaged over by the retaining disc (8). [2] Current discharge element according to claim 1, characterized by that the spacer projection (11) is hollow cylindrical and surrounds the opening (10). [3] Current discharge element according to claim 1 or 2, characterized by that the carrier (2) is made of metal and the spacer projection (11) is designed as a through-position. [4] Current discharge element according to claim 1 or 2, characterized by that the carrier (2) is made of plastic and the spacer projection (11) is formed in one piece. [5] Current diverting element according to one of the preceding claims, characterized by that the carrier (2) has at least two openings (10), each with an associated spacer projection (11). [6] Current discharge element according to claim 5, characterized by that the two spacer projections (11) have the same geometry or different geometries. [7] Current discharge element according to one of the preceding claims, characterized by that one or more stiffening ribs (20) formed by groove-like depressions are provided on the support (2). [8] Current discharge element according to one of the preceding claims, characterized bythat the holding disc (8) is fastened to the carrier (2) via a plurality of holding elements (9) formed on the carrier (2), each passing through an opening (15) in the holding disc (8).

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