Electric machine and motor vehicle

Abstract

Electric machine (10) comprising a stator and a rotor mounted therein so as to be rotatable about a central longitudinal axis (14) of a motor shaft of the electric machine (10) and a slip ring module (12) connected to the motor shaft, which is rotationally fixed to the rotor and rotatable relative to a slip ring (24) of the electric machine (10) and has a wire guide channel (18, 38), wherein - a first section (20) of the wire guide channel (18, 38) extends from the slip ring (24) in an axial direction parallel to the central longitudinal axis (14) and a subsequent second section (22) of the wire guide channel (18, 38) extends radially outwards to the wire outlet (32), characterized in that - a contact wire (26, 40) for electrically connecting a rotor winding to the slip ring (24) is guided through the wire guide channel (18, 38) from the latter to a wire outlet (32) of the slip ring module (12), - in the second section (22) an elastic sealing element (42, 54) surrounding the contact wire (26, 40) is arranged to seal the wire guide channel (18, 38) against the ingress of a lubricant at the wire outlet (32), - the sealing element (42, 54) is designed as a sealing plug (42) which is arranged in the second section (22) of the wire guide channel (18, 38) and surrounds the contact wire (26, 40) in the area of ​​the second section (22), - the sealing plug (42) in the second section (22) is fixed by a thermosetting molding compound (52) which at least in the first section (20) surrounds and fixes the contact wire (26, 40).

Description

[0001] The present invention relates to an electric machine, in particular for a motor vehicle, and to a motor vehicle with such an electric machine.

[0002] Electric machines have been known in many variations for a long time, but they remain of particular importance in numerous technical and industrial applications. It is foreseeable that the importance of electric machines, especially in the field of automotive engineering, will increase even further in the future. Against this backdrop, further improvements and optimizations are clearly desirable.

[0003] EP 3 261 231 A1 describes a connecting element for an AC machine of a power generation unit. This connecting element has a first end section for connecting to a main conductor arranged in an axial seat of a rotor, and a second end section for connecting to a conductor element. A sealing element with a cross-section that is at least substantially C-shaped is provided for the second end section. The sealing element can, for example, be a sealing ring that can bear against a conductor entry point or the outer surface of the rotor outside of the rotor. This is intended to prevent the escape of cooling gas.

[0004] US patent 2015 / 0288120A1 describes a slip ring structure comprising multiple slip rings rotatable around a common axis for different phases. The slip rings are contacted by busbars extending axially. At at least one axial position, one of the busbars, which has a shorter axial length, has a larger cross-section perpendicular to the axis. This is intended to facilitate or eliminate the need for adjustment after assembly.

[0005] WO 2018 / 011740A1 describes a pumping device for a fluid reservoir for dispensing a fluid. It comprises a piston-cylinder unit forming a pump chamber, located between an operating element and a head. An inlet valve is located at the inlet of the pump chamber, and an outlet valve is located at the outlet of the pump chamber. The outlet valve is situated at the outlet of the operating element, and the outlet opening of this opening forms a valve seat, allowing the outlet valve to close the outlet opening from the outside.

[0006] Electrical machines can often be operated as electric motors or as generators. For example, an AC generator for installation in a vehicle is known from DE 10 2006 025 394 A1. This generator features slip rings rotatable on a rotating shaft and brushes that slide on these rings and are held in a brush holder. The slip rings and the brush holder are covered by a slip ring cover. A rear cover, which conceals the brushes, has a first ventilation opening that connects an interior containing the brush grips to the exterior of the AC generator. A second ventilation opening connects an interior containing the brushes within the brush holder to the exterior of the AC generator. The interior containing the brush grips is sealed by gaskets.These sealing parts can be located at the axial ends of the brush holder and the slip ring cover and consist of a sheet-like rubber material.

[0007] Another application example, DE 43 14 628 C1 discloses an electric rotary and swivel unit with a directly driven brushless motor, for example, for industrial robots. A stator serves as the base housing with stepless swivel angle adjustment, integrated air passage, and integrated electrical signal and power transmission with connectors. No external hoses or cables are present. The entire unit is dustproof and splashproof, while simultaneously featuring a modular design and easy replacement of the rotary table. Several channels run through a distributor flange, each connecting to a corresponding connection channel in the rotary distributor. Seals can be arranged on both sides of each connection between a channel and a connection channel.

[0008] In another application example, a liquid-cooled electric motor is known from DE 11 2013 003 975 T5. This motor features a coolant distribution system to distribute a liquid coolant along a first and a second path. The first path leads into a hollow rotor shaft, from where, during operation, the coolant can flow radially outwards through shaft radial holes in the hollow rotor shaft and then longitudinally into a rotor coolant passage in the rotor and into a collection tank. The second path, during operation, leads radially outwards through inlet radial holes in a coolant inlet port and then longitudinally into a peripheral coolant passage located in a gap between a housing and a stator of the electric motor, and finally also into the collection tank. For many internal flow paths, liquid-tight seals are not required, which can save costs.The only liquid-tight seals required are those that connect between the coolant and the external environment.

[0009] The object of the present invention is to improve the reliability of an electric machine, particularly in wet-running operation. This object is achieved according to the invention by the subject matter of the independent claims. Advantageous embodiments and further developments of the present invention are specified in the dependent claims, in the description, and in the figures.

[0010] The electrical machine according to the invention comprises a stator and a rotor mounted therein so as to be rotatably displaceable about a central longitudinal axis of a motor shaft of the electrical machine, as well as a slip ring module connected to, i.e., coupled to, the motor shaft. The slip ring module is rotationally fixed to the rotor and rotatable relative to a slip ring of the electrical machine and has at least one wire guide channel through which a contact wire is guided for electrically connecting a respective rotor winding to the slip ring. The at least one wire guide channel extends at least substantially from the slip ring to a wire outlet of the slip ring module. A first section of the wire guide channel runs axially parallel to the central longitudinal axis, originating at least substantially or nearly from the slip ring.A second section of the wire guide channel, adjoining the first section, extends radially outwards to the wire outlet. The wire outlet is therefore a radially outer end of the second section of the wire guide channel, essentially an opening in a side or outer wall of the slip ring module. The wire outlet can also encompass an area of ​​the slip ring module immediately surrounding this opening.

[0011] According to the invention, in the second section of the wire guide channel, an elastic sealing element surrounding the contact wire guided therein is arranged at the wire outlet to seal the wire guide channel against the ingress of lubricant. In other words, the sealing element seals the wire guide channel, in particular the second section of the wire guide channel, or the wire outlet, against a surrounding area of ​​the slip ring module or the electrical machine. The sealing element is designed as a sealing plug inserted into the second section of the wire guide channel. A sealing element can also be designed as an O-ring. Such an O-ring can, for example, rest on the wire outlet, i.e., at the radially outer end of the second section of the wire guide channel, or be inserted into a radially outer end region of the second section of the wire guide channel.

[0012] In the present invention, the sealing element is designed as a sealing plug which is arranged in the second section of the wire guide channel and surrounds the contact wire in the region of the second section of the wire guide channel. The sealing plug can partially, but preferably completely, penetrate or extend through the second section of the wire guide channel in a radial direction, i.e., perpendicular to the central longitudinal axis or to the motor shaft. By designing the sealing element as such a sealing plug inserted into the wire guide channel with a significant radial extension, a particularly good sealing effect as well as a particularly reliable fit or retention of the sealing plug in its intended position, i.e., in the second section of the wire guide channel, can advantageously be achieved.The sealing plug can be inserted into the second section of the wire guide channel either from the inside in a radially outward direction or from the outside in a radially inward direction. The former can advantageously provide a particularly reliable hold or seat for the sealing plug in the second section of the wire guide channel under the influence of centrifugal forces such as those occurring during the operation of the electric machine, while the latter can advantageously enable particularly simple manufacturing of the electric machine.

[0013] In the present invention, the sealing plug is fixed or held in the second section of the wire guide channel by a thermosetting molding compound, which, at least in the first section of the wire guide channel, encases and secures the contact wire. This can be, in particular, the thermosetting molding compound also mentioned elsewhere. The proposed fixation of the sealing plug by the molding compound advantageously prevents, in a particularly simple and cost-effective manner, the sealing plug from being pushed or pulled out of the second section of the wire guide channel, for example, due to centrifugal forces occurring during operation of the electric machine. Particularly advantageous is the fact that no additional fastening elements are required to fix the sealing plug, which can advantageously reduce the complexity as well as the manufacturing and cost effort of the electric machine.To secure the sealing plug, the molding compound can, for example, partially enclose it. Depending on the design of the sealing plug and / or the choice or combination of materials, the molding compound can hold or fix the sealing plug in place by means of a form-fit, material-fit, and / or force-fit connection.

[0014] The electrical machine according to the invention can preferably be a wet-running synchronous machine – that is, at least partially submerged in oil – for example, a current-excited synchronous machine. In a manner known in principle, the motor shaft can be fixedly connected to the rotor or driven by the rotor during operation of the electrical machine. The slip ring is part of a sliding contact, thus providing an electrical connection between a stationary part of the electrical machine and a rotating part.

[0015] Advantageously, the present invention, through the sealing element arranged in the wire guide channel, prevents the oil, which serves as a lubricant, from reaching the sliding contact, i.e., the slip ring. While it is generally known for electrical machines to provide external seals, for example on both sides of the slip ring, such as sealing rings surrounding the motor shaft or the slip ring module, the present invention is based on the understanding that the lubricant can reach the wire guide channel or the wire outlet, for example through cracks in a rotor filling material. From there, the lubricant can then creep along the contact wire through the wire guide channel—particularly due to capillary action—and thus reach the sliding contact or the slip ring. In doing so, it can circumvent the seals provided to date.If the lubricant reaches the sliding contact, it can, for example, impair the electrical contact, completely or partially interrupt the electrical flow, lead to damage or additional wear, and thus ultimately reduce the reliability and service life of the electric machine. The sealing element provided here in the second section of the wire guide channel closes or seals this previously unaddressed oil path, thereby preventing or reducing the aforementioned adverse effects.

[0016] The electric machine can have a plurality of circumferentially distributed wire guide channels, the second sections of which can each be closed or sealed with their own sealing element. Different wire guide channels, or the various contact wires running within them, allow different windings of the rotor, i.e., different poles or pole pairs of the rotor, to be contacted and supplied with electric current to generate a rotor field. For the sake of simplicity and clarity, however, the present invention will be explained here essentially for one wire guide channel and, accordingly, for one sealing element.

[0017] In an advantageous embodiment of the present invention, the wire guide channel is largely filled with the thermosetting molding compound surrounding the contact wire. The molding compound thus electrically insulates and mechanically fixes the respective contact wire. The molding compound can, for example, be injected or cast into the wire guide channel while the contact wire is arranged or held within it. Alternatively, the molding compound can form the wire guide channel by surrounding the contact wire. For manufacturing the electrical machine, the contact wire can, for example, first be inserted axially into the respective wire guide channel and then be offset radially outwards, so that a bent, radially outwardly projecting end of the contact wire passes through the second section of the wire guide channel.In this position, the contact wire can then be held or clamped. The sealing element can already be on the bent end of the contact wire or slid onto it after the contact wire has been inserted or positioned. Once both the contact wire and the sealing element are in place, the molding compound can be injected or poured in. As soon as the molding compound has solidified or hardened, the wire guide channel is formed or filled, and the contact wire is fixed by the molding compound. As explained in more detail above, the sealing element can also be advantageously held or fixed by the molding compound.Although the contact wire is embedded directly and immediately in the molding compound in this way, a gap may still exist between the contact wire and the molding compound, for example, due to air inclusions, surface roughness, and / or similar factors. Such a gap can be, for example, a few micrometers, which may be sufficient as a creepage distance for the lubricant to spread along the contact wire. It is therefore particularly advantageous that the sealing element prevents the lubricant from penetrating. Due to the elasticity of the sealing element, it can, for example, lie closer to the contact wire than the thermosetting molding compound typically does.

[0018] In a further advantageous embodiment of the present invention, the sealing element is made of an elastomer, in particular an ethylene acrylate elastomer (AEM), with a dielectric strength of at least 15 kV / mm. The sealing element is thus made of a material that is simultaneously elastic and exhibits a relatively high electrical insulation class as well as a relatively high tracking resistance or a relatively high CTI value (Comparative Tracking Index). This advantageously achieves, on the one hand, the desired sealing of the second section of the wire guide channel or the wire outlet, and on the other hand, improves the electrical insulation of the contact wire and thus the tracking and dielectric strength of the electrical machine.For example, the sealing element can increase the creepage distance between a part of the contact wire projecting radially outwards from the wire outlet and an outer surface or surface of the slip ring module surrounding the wire outlet.

[0019] In an advantageous embodiment of the present invention, the sealing plug projects radially outwards beyond an end of the second section of the wire guide channel formed by the wire outlet. In other words, the sealing plug protrudes externally beyond an outer wall or surface of the slip ring module in the area of ​​the wire outlet. This advantageously further improves the electrical insulation effect of the sealing plug, as the leakage current or breakdown distance between the radially outwardly projecting portion of the contact wire from the sealing plug and the surrounding surface of the slip ring module can be increased. Furthermore, this allows the sealing plug to advantageously bear against the contact wire over a longer distance, thereby achieving an improved and particularly reliable sealing effect.Furthermore, this design advantageously offers the possibility of widening an area of ​​the sealing plug projecting radially outwards beyond the wire outlet in an axial direction, thereby improving on the one hand the insulating effect of the sealing plug and on the other hand positioning accuracy or positioning reliability and / or the seat or retention of the sealing plug in its intended position.

[0020] In an advantageous embodiment of the present invention, the sealing plug has a shape that is at least substantially mushroom-shaped, comprising a shaft region and a comparatively wider head region. The largest diameter of the head region is larger than the smallest diameter of the second section of the wire guide channel or the diameter of the wire outlet. In other words, the sealing plug is shaped such that it can be partially inserted into the wire guide channel—namely, with its shaft region—while the head region is too wide or too large for this purpose. As described, this allows the electrical insulation effect of the sealing plug to be further improved, if necessary.Similarly, it can be prevented, for example, that the sealing plug is pushed through the second section of the wire guide channel or too far into it during the manufacturing of the electric machine. Instead, the widened head section can be designed to rest against a surface surrounding one end of the second section of the wire guide channel or the wire outlet. This is particularly easy and reliable to implement during the manufacturing of the electric machine. Depending on the design, the head section can be positioned radially inside or outside.Depending on the elasticity of the sealing plug, the diameter of the shaft section can, at least partially or partially, correspond to the diameter of the second section of the wire guide channel, or it can be so much larger than the diameter of the second section of the wire guide channel that, due to its elasticity (i.e., its elastic deformability or compressibility), the shaft section can still be inserted into the second section of the wire guide channel. The latter can advantageously result in a particularly good sealing effect of the sealing plug.

[0021] In an advantageous embodiment of the present invention, the sealing plug has a constriction with a reduced diameter. In other words, the sealing plug has at least one area with a diameter that is smaller than the diameters of the areas of the sealing plug adjoining this area on both sides in the longitudinal direction of the sealing plug. In particular, the reduced diameter of the constriction can be smaller than the diameter, especially the smallest diameter, of the second section of the wire guide channel. This design of the sealing plug allows the molding compound to enter the area of ​​the constriction and thereby enclose, at least on one side of the constriction, an area with a correspondingly larger diameter of the sealing plug.This allows for an undercut or anchor fixation, whereby the molding compound, after hardening, holds or fixes the sealing plug in the second section of the wire guide channel in a form-fitting manner. This allows the sealing plug to be fixed in a particularly simple and reliable way, thus advantageously further improving the reliability of the electric machine without the need for additional parts or components.

[0022] In an advantageous embodiment of the present invention, a widening of the sealing plug, which limits the constriction on one side facing the central longitudinal axis, is partially interrupted in its circumferential direction. In other words, this inner widening of the sealing plug is only formed in certain areas up to the full diameter of the second section of the wire guide channel and has sections or areas with a diameter smaller than the diameter of the second section of the wire guide channel. The diameter in these interruptions can correspond at least substantially to the diameter of the constriction or lie between the diameter of the constriction and the diameter of the second section of the wire guide channel. The at least one interruption of the widening advantageously creates or forms a connection to or access to the constriction.Through this connection or access point, the molding compound enclosing the contact wire – which is still liquid or viscous at that time – can flow radially outwards from the inside, i.e., from the side facing the central longitudinal axis, to the constriction during the manufacturing of the electrical machine. This allows the molding compound to reliably fill an area of ​​the second section of the wire guide channel not occupied by the sealing plug, thereby ensuring a particularly reliable fixation of the sealing plug by the molding compound.In order to achieve the most uniform possible filling of the area or volume of the second section of the wire guide channel not occupied by the sealing plug with the molding compound, as well as a particularly reliable and uniform fixing of the sealing plug by the molding compound, the widening of the sealing plug may preferably have several interruptions arranged in the circumferential direction, in particular evenly distributed.

[0023] Another aspect of the present invention is a motor vehicle comprising at least one electric machine according to the invention. If the electric machine is a drive motor for generating a force or torque for propelling the motor vehicle, the motor vehicle can accordingly be an electric or hybrid vehicle.

[0024] Further features of the invention may become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures themselves, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0025] The drawing shows in: Fig. 1. A schematic cutaway perspective view of part of an electrical machine; Fig. 2 a schematic perspective view of a sealing plug for a wire guide channel of the electric machine; Fig. 3 a partial schematic sectional view of an area around the sealing plug in an unfilled state; Fig. 4 a partial schematic sectional view of an area around the sealing plug in a filled state; and Fig. 5 a partial schematic sectional view of an area with an alternative sealing element.

[0026] In the figures, identical and functionally equivalent elements are each provided with the same reference symbols.

[0027] Fig. Figure 1 shows a schematic, cutaway perspective view of a part of an electric machine 10. In particular, a part of a slip ring module 12 is shown, which can rotate about a central longitudinal axis 14. The central longitudinal axis 14 runs longitudinally and centrally through a shaft receiving space 16 surrounded by the slip ring module 12, in which a motor shaft of the electric machine 10 can be arranged. A wire guide channel 18 runs in the slip ring module 12. This wire guide channel 18 has a first section 20 extending axially parallel to the central longitudinal axis 14 and a second section 22 extending radially through a wall of the slip ring module 12. A slip ring 24, which also surrounds the shaft receiving space 16, is also shown.In the wire guide channel 18, a contact wire 26 is arranged, which electrically contacts the slip ring 24 and is led out of the second section 22 of the wire guide channel 18 at its other end. In the complete electric machine 10, the end of the contact wire 26 leading out of the second section can be routed to a rotor winding, i.e., electrically connected to one.

[0028] The contact wire 26, analogous to the wire guide channel 18, has an axial section 28 which runs parallel to the central longitudinal axis 14 in the first section 20 and thus also radially outwards. Also analogous to the wire guide channel 18, a radial section 30 of the contact wire 26 connects to this axial section 28. This radial section 30 is guided radially outwards through the second section 22. A radially outward end of the second section 22 is here referred to as the wire outlet 32, from which the radial section 30 of the contact wire 26 protrudes from the slip ring module 12.

[0029] The wire guide channel 18 is shown here in an empty, i.e., unfilled, state to better illustrate the path of the contact wire 26. During further manufacturing of the electrical machine 10, the wire guide channel 18 will be enclosed, i.e., the area surrounding the contact wire 26 will be filled to electrically insulate and spatially fix the contact wire 26.

[0030] In the axial direction, i.e. in the direction along the central longitudinal axis 14, sealing rings are arranged on both sides of the wire outlet 32, namely a first seal 34 on one side facing the slip ring 24 and a second seal 36 on the opposite side of the wire outlet 32.

[0031] The electric machine 10 or the slip ring module 12 can have a plurality of wire guide channels 18, each with its own contact wire 26 arranged therein. An additional wire guide channel 38 with another contact wire 40 is shown here as an example. The descriptions and explanations given here for the wire guide channel 18 and the contact wire 26, and for the additional wire guide channel 38 and the additional contact wire 40, apply analogously to this channel as well as to other wire guide channels and contact wires not shown here.

[0032] Despite the seals 34, 36, it has been shown that during operation of the electric machine 10, oil can reach the wire outlet 32 ​​and travel along the contact wire 26 through the wire guide channel 18 to the slip ring 24 or a sliding contact formed by the slip ring 24 and the contact wire 26. To prevent this, the wire guide channel 18, or rather its second section 22, is sealed by an additional sealing element that surrounds the contact wire 26 in the area of ​​the second section 22 or at the wire outlet 32, in order to prevent or reduce the ingress of oil into the wire guide channel 18.

[0033] Such a sealing element is in Fig. Figure 2 shows a sealing plug 42 in a schematic perspective view. The sealing plug 42 has a generally mushroom-shaped base with a widened head region 44 and a narrower shaft region adjoining it. A constriction 46 is provided in the shaft region. On one side of the constriction 46 opposite the head region 44, the sealing plug 42 has several circumferentially evenly distributed widenings 48. These widenings 48 are interrupted circumferentially by gaps 50. In the region of the gaps 50, the sealing plug 42 therefore has a smaller diameter than in the region of the widenings 48.

[0034] The sealing plug 42 can, for example, be inserted or pushed radially from the outside to the inside onto the radial piece 30 and into the second section 22 during the manufacture of the electric machine 10. An underside of the head region 44 facing the constriction 46 can then rest on an outer surface of the grinding module 12 in the area of ​​the wire outlet 32.

[0035] For the sake of clarity, the wire guide channel 18 is shown here in an unfilled state, i.e. empty except for the contact wire 26 and the sealing plug 42, during the manufacture of the electrical machine 10.

[0036] Fig. Figure 4, also a partial schematic sectional view, shows the area around the second section 22. Here, however, the wire guide channel 18 is shown in a filled state. Specifically, the wire guide channel 18 is filled with a thermosetting molding compound 52. This molding compound 52 thus encloses the contact wire 26 and at least partially the sealing plug 42. In particular, the molding compound 52 fills the second section 22 of the wire guide channel 18 in the area of ​​the constriction 46 of the inserted sealing plug 42, thereby fixing not only the contact wire 26 but also the sealing plug 42. The shaft receiving space 16, on the other hand, is not filled by the molding compound 52 and thus remains free to accommodate the motor shaft of the electric machine 10 (not shown here). The shaft receiving space 16 can, for example, be separated from the area filled here by the molding compound 52.Likewise, during a manufacturing process, a placeholder element corresponding in its shape to the shaft receiving space 16 can be inserted into the slip ring module 12, then overmolded or cast with the molding compound 52 and subsequently removed after at least partial solidification or hardening of the molding compound 52 to release the shaft receiving space 16.

[0037] Fig. Figure 5 shows a partial schematic sectional view of an area around a radial section of the further wire guide channel 38 with an alternatively designed sealing element. The sealing element for sealing the further wire guide channel 38 is here designed as an O-ring 54 surrounding the further contact wire 40. Depending on the application or requirements, in a specific electrical machine 10, all sealing elements can preferably be of the same type, i.e., either as a sealing plug 42 or as an O-ring 54.

[0038] Overall, the examples described show how wire exits of wires for electrical contacting rotor windings or sliding contacts on the slip ring module 12 can be sealed by means of a sealing element, in particular an elastomer sealing plug with an armature fixing, in order to improve oil tightness and thus reliability, especially in a wet, i.e. oiled, operation of the electric machine 10. Reference symbol list 10 electric machine 12 Slip ring module 14 Central longitudinal axis 16 wave recording room 18 wire guide channel 20 first section 22 second section 24 slip ring 26 contact wire 28 Axial piece 30 radial piece 32 Wire outlet 34 first seal 36 second seal 38 additional wire guide channels 40 additional contact wires 42 sealing plugs 44 Head area 46 Constriction 48 widenings 50 interruptions 52 Molding compound 54 O-ring

Claims

[1] Electric machine (10) comprising a stator and a rotor mounted therein so as to be rotatable about a central longitudinal axis (14) of a motor shaft of the electric machine (10) and a slip ring module (12) connected to the motor shaft, which is rotationally fixed to the rotor and rotatable relative to a slip ring (24) of the electric machine (10) and has a wire guide channel (18, 38), wherein - a first section (20) of the wire guide channel (18, 38) extends from the slip ring (24) in an axial direction parallel to the central longitudinal axis (14) and a subsequent second section (22) of the wire guide channel (18, 38) extends radially outwards to the wire outlet (32), characterized by , that - a contact wire (26, 40) for electrically connecting a rotor winding to the slip ring (24) is guided through the wire guide channel (18, 38) from the latter to a wire outlet (32) of the slip ring module (12), - in the second section (22) an elastic sealing element (42, 54) surrounding the contact wire (26, 40) is arranged to seal the wire guide channel (18, 38) against the ingress of a lubricant at the wire outlet (32), - the sealing element (42, 54) is designed as a sealing plug (42) which is arranged in the second section (22) of the wire guide channel (18, 38) and surrounds the contact wire (26, 40) in the area of ​​the second section (22), - the sealing plug (42) in the second section (22) is fixed by a thermosetting molding compound (52) which at least in the first section (20) surrounds and fixes the contact wire (26, 40). [2] Electric machine (10) according to claim 1, characterized by , that the wire guide channel (18, 38) is largely filled with the thermosetting molding compound (52) surrounding the contact wire (26, 40). [3] Electric machine (10) according to claim 1, characterized by, that the sealing element (42, 54) is made of an elastomer, in particular an ethylene acrylate elastomer, with an electrical breakdown strength of at least 15 kV / mm. [4] Electric machine (10) according to any one of the preceding claims, characterized by , that the sealing plug (42) extends radially outwards beyond an end of the second section (22) of the wire guide channel (18, 38) formed by the wire outlet (32). [5] Electric machine (10) according to any one of the preceding claims, characterized by , that the sealing plug (42) has at least an essentially mushroom-shaped form with a shaft area and a head area (44) that is wider in comparison to the shaft area, wherein a largest diameter of the head area (44) is larger than a smallest diameter of the second section (22) of the wire guide channel (18, 38). [6] Electric machine (10) according to any one of the preceding claims, characterized by, that the sealing plug (42) has a constriction (46) with a reduced diameter. [7] Electric machine (10) according to claim 6, characterized by , that a widening (48) of the sealing plug (42) limiting the constriction (46) on one side facing the central longitudinal axis (14) is interrupted in its circumferential direction in certain areas. [8] Motor vehicle comprising an electric machine (10) according to any one of the preceding claims.

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