DE102020119719A1 - Discharge device for an electrical machine and electrical machine with the discharge device - Google Patents

Abstract

A discharge device 15 for an electrical machine 1 for discharging an electrical charge and/or voltage from a rotor 2 via a shaft 4 to a housing section 7, with the housing section 7 delimiting a housing space 6, with a first contact device 16 for electrical and mechanical Connection to the shaft 4, with a second contact device 17 for the electrical and mechanical connection to the housing section 7, the first and the second contact device 16, 17 being rotatable relative to one another about a main axis H and electrically in a contact space 18 sealed off from the housing space 6 are in connection with each other, proposed, wherein the contact space 18 is filled with an electrically conductive liquid 19, wherein the first and the second contact device 16, 17 are electrically conductively connected to one another via the electrically conductive liquid 19.

Description

The invention relates to a discharge device with the features of the preamble of claim 1. The invention also relates to an electrical machine with the discharge device.

Electrical machines, in particular electrical traction machines, are electrically charged during operation by induced shaft voltages. In addition, circulating high-frequency currents can arise in motors with high performance classes. Such electrical machines generally have a rotor and a rotor shaft, which are mounted in a housing via roller bearings. Due to electrical discharges or the circulating high-frequency currents, the roller bearings can be damaged. In order to avoid this, a dissipation of this electrical energy is necessary. For example, grounding brushes or radially acting grinding elements (carbon brushes) are known for this purpose, which serve to ground the rotor shaft. Furthermore, axially acting shaft grounding systems are known.

The pamphlet JP 2013174326 A discloses an electronic anti-corrosion device having a rotary shaft driven by an electric motor; bearings that rotatably support the rotary shaft; a discharge element electrically connected to the rotary shaft; and a ground wire grounding the discharge element by electrically connecting the discharge element to the rotary shaft via a conductor body connected to the end face of the rotary shaft.

The object of the invention is to provide a discharge device which is characterized by improved discharge capability and freedom from wear.

This object is achieved by a discharge device having the features of claim 1 and an electrical machine having the features of claim 8. Preferred or advantageous embodiments of the invention result from the dependent claims, the following description and the attached figures.

The invention relates to a discharge device which is designed and/or suitable for an electrical machine. The electrical machine has a housing section, the housing section defining and/or delimiting a housing space. In particular, the housing section is part of a housing and/or forms this. The housing is preferably constructed in several parts, with the housing section forming part of the housing, for example an end shield. In particular, the housing section is connected to ground and/or grounded.

The electrical machine has a shaft which defines a main axis with its axis of rotation. Furthermore, the electrical machine has a stator and a rotor, which are arranged concentrically and/or coaxially to one another. The shaft is electrically and gear-connected to the rotor. In particular, the shaft is driven via and/or by the rotor. The shaft is particularly preferably designed as a rotor shaft which is preferably non-rotatably, rigidly and/or integrally connected to the rotor. Preferably, the housing portion is electrically and mechanically connected to the stator.

The shaft and the rotor are rotatably mounted in the housing space. In particular, the electrical machine has at least or exactly two bearing devices, which form or also form the rotor bearing. The rotor is preferably arranged between the two bearing devices in the housing space, with the shaft being rotatably mounted via the bearing devices in the housing space and/or on the housing section.

The discharge device is designed and/or suitable for dissipating an electrical charge and/or voltage, starting from the rotor via the shaft to the housing section. In particular, the diverting device forms an electrical connection between the shaft and the housing section. In particular, there is a permanent electrical connection between the shaft and the housing section, which is present both stationary and dynamic, ie during operation of the electrical machine.

The diverting device has a first contact device and a second contact device. The first contact device is used for the electrical connection to the shaft. Furthermore, the first contact device is used for the mechanical connection to the shaft, in particular so that the first contact device is fixed to the shaft. The second contact device is used for the electrical connection to the housing section. Furthermore, the second contact device is used for the mechanical connection to the housing section, in particular so that the second contact device is fixed to the housing section. The two contact devices can be rotated relative to one another, in particular when the electrical machine is in operation. During operation of the electrical machine, the shaft rotates about the main axis, with the first contact device being carried along by the rotating shaft and the second contact device remaining stationary on the housing section.

The first and second contact devices are electrically connected to one another in a contact space that is sealed off from the housing space. The contact space and the housing space are preferably separated from one another in a sealing manner and/or sealed off from one another. The contact space is delimited in particular in the axial and/or radial direction by the first and/or the second contact device. The contact space is preferably defined as an annular space surrounding the main axis, which is formed between the first and the second contact device. The two contact devices are arranged coaxially to one another in relation to the main axis, the first contact device being arranged on an axial end face of the shaft and the second contact device being arranged opposite thereto on the housing section. Thus, the discharge device is implemented as a so-called "frontal shaft earthing device".

In the context of the invention it is proposed that the contact space is filled with an electrically conductive liquid. For example, the electrically conductive liquid can be in the form of an oil, fat, liquid metal, ionic liquid or the like, which are themselves electrically conductive and/or have electrically conductive additives added to them. The contact space is preferably completely filled with the electrically conductive liquid. Alternatively, however, the contact space can also be partially and/or largely filled with the electrically conductive liquid. The first and the second contact device are electrically conductively connected to one another via the electrically conductive liquid. In particular, the two contact devices are spaced apart from one another in the contact space, with electrical contact being made exclusively via the electrically conductive liquid. In particular, a current path thus runs from the rotor via the shaft and the first contact device via the electrically conductive liquid to the second contact device and the housing section. The current path formed by the diverting device has a lower resistance compared to the storage devices, so that the discharge currents and/or voltages are diverted via the diverting device.

The advantage of the invention is, in particular, that a wear-free contact is established between the two diverting devices via the electrically conductive liquid, so that the diverting device can be operated with very little friction and without wear. In contrast to friction contacts, as is known from the prior art, no conductive abrasion occurs in the proposed discharge device, which means that there is no risk of short circuits due to abrasion in the electrical machine. A further advantage of the invention is that the contacting via the electrically conductive liquid enables position-independent operation of the discharge device, since permanent contact is established between the two contact devices via the electrically conductive liquid.

A specific embodiment of the invention provides that one of the contact devices is designed as a sleeve and the other contact device as a grounding rod. In principle, the sleeve can be assigned to the housing section and the grounding rod to the shaft. However, the sleeve is preferably associated with the shaft and the grounding rod is associated with the housing section. In particular, the sleeve is embodied in a rough form as a cylinder sleeve that is closed on one side. In particular, the grounding rod is embodied in a rough form as a cylindrical rod. Preferably, the sleeve and grounding rod are formed from an electrically conductive material such as steel, iron, copper or the like. The sleeve has the contact space with the electrically conductive liquid, with the grounding rod being arranged in sections in the sleeve, so that the grounding rod dips into the electrically conductive liquid in the contact space. In particular, the grounding rod and the sleeve can be rotated relative to one another about the main axis, with the grounding rod and the sleeve being in permanent contact via the electrically conductive liquid when they are rotated relative to one another. Preferably, the sleeve and the grounding rod are arranged coaxially and/or concentrically with respect to the main axis. The grounding rod is preferably inserted into the sleeve in the axial direction with respect to the main axis and is sealed off from the sleeve. In this case, the contact space is delimited in the axial direction on the one hand by the sleeve itself and on the other hand by the grounding rod which is sealingly accommodated in the sleeve. A discharge device is thus proposed which is characterized by a simple and inexpensive design and can also be easily integrated into an existing system.

In a further specification, it is provided that the sleeve has a sealing section for accommodating a sealing device and a contact section adjoining the sealing section for forming the contact space. In particular, the contact section directly adjoins the sealing section in the axial direction with respect to the main axis. The sleeve can be designed as a shaped sheet metal component, with the contact section and the sealing section being formed by metal forming. The contact section preferably has a smaller inside diameter than the sealing section. In particular, the grounding rod is arranged at a distance from the contact section in the axial and in the radial direction. Here is the Measure the distance in the axial and radial directions so that there is no contact between the earthing rod and the sleeve due to the tolerances. Alternatively or optionally in addition, the distance in the axial and/or radial direction is dimensioned so small that the volume of the contact space is minimal. The grounding rod is preferably supported in a sealing manner on the sleeve within the sealing section and/or is guided over the sealing section in a sealing manner. The contact section is preferably closed in an axial direction with respect to the main axis and the sealing section is open in an opposite axial direction, so that the grounding rod is and/or can be pushed in the axial direction via the sealing section into the contact section. For example, the contact section is pre-filled with the electrically conductive liquid before the grounding rod is installed, with the grounding rod being immersed in the electrically conductive liquid when it is pushed into the sleeve and/or sealing the contact space in a fluid-tight manner. A discharge device is proposed which is characterized by simple assembly and thus simple and inexpensive installation.

In a further specific implementation, the diverting device has a sealing device which is designed and/or suitable for sealing the contact space. In particular, the sealing device has the function of protecting the contact space from the environment, in particular the housing space, from the electrically conductive liquid escaping and/or from the ingress of foreign particles, such as dust, moisture, splash water, oil, etc., from the environment . For this purpose, the contact space is preferably of closed design and is separated from the environment in the axial direction by the sealing device. In particular, the sealing device is used for dynamic and static sealing of the contact space, so that it is sealed off from the environment, in particular from the housing space, both at a standstill and during operation. The sealing device preferably forms a fluid-tight, in particular oil-tight, separation of the contact space. The sealing device is accommodated in the sealing section with a positive and/or non-positive fit in the axial direction, with respect to the main axis, the grounding rod being supported in a sealing manner via the sealing device on an inner circumference of the sleeve. In particular, the sealing device is held in a non-positive manner via a press fit in the sealing section. Alternatively or optionally in addition, the sealing device is held in a form-fitting manner in the axial direction and/or in the opposite axial direction. The sealing device is preferably designed as a contacting rotary seal, for example as a radial shaft sealing ring, a felt ring or a shaft lip seal. A particularly tight system is thus proposed, which can be used, for example, for use in both dry and wet environments.

In a further development it is provided that the sealing device is designed as a double-acting rotary seal. For this purpose, the sealing device has a first and a second sealing lip, which, spaced apart from one another in the axial direction, abut radially on an outer circumference of the grounding rod. In principle, the first and the second sealing lip can each be formed by two separate seals, e.g. radial shaft sealing rings. However, the sealing device preferably has a cylindrical base body, with the two sealing lips being formed on an inner circumference of the base body. In particular, the base body and the two sealing lips are made of an elastic material. Alternatively, however, the base body can be made of a harder material than the two sealing lips, e.g. a hard plastic, metal or the like. The two sealing lips ensure particularly tight sealing, in particular during rotation of the shaft, with the electrically conductive liquid escaping or foreign particles entering being significantly reduced or prevented.

In a further embodiment, it is provided that the sleeve has a form-fitting contour on its inner circumference and the grounding rod has a counter-contour on its outer circumference. The form-fitting contour and the counter-contour are in positive engagement with one another in the axial direction in relation to the main axis, so that the grounding rod is secured against being pulled out of the sleeve. The grounding rod is preferably secured to the sleeve at a defined insertion depth via the form-fitting contour. In particular, the form-fitting contour can be formed by at least one collar pointing radially inward and the counter-contour by at least one collar pointing radially outward, so that an end stop for the grounding rod is formed from the sleeve at least in an axial direction. In particular, the form-fitting contour or the counter-contour has a further collar, so that an end stop for the grounding rod is formed both in the axial direction and in the opposite axial direction. The grounding rod can thus be rotated in the circumferential direction and secured against displacement in the sleeve in the axial direction. Thus, a discharge device is proposed, which is designed as a preassembled structural unit.

In a further realization it is provided that the second contact device has a fastening section at the end. In particular, the fastening section serves to fasten the second contact device to the housing cut. In principle, the sleeve can have the fastening section for fastening the sleeve to the housing section. However, the grounding rod preferably has the fastening section for fastening the grounding rod to the housing section. The diverting device has a fastening means which is designed and/or suitable for the detachable fastening of the fastening section to the housing section. The fastening means can be arranged and/or can be arranged on the fastening section in a positive and/or non-positive manner in order to secure the second contact device on the housing section. For example, the fastening section has an external or internal thread, with the fastening means being able to be designed accordingly as a nut for the external thread or as a screw for the internal thread. Preferably, the second contact device can be and/or is connected to the housing section in a fixed manner, in particular in a rotationally fixed manner, via the fastening section and the fastening means. A discharge device is thus proposed which can be mounted on the housing section in a simple manner and can be inexpensively replaced in the event of servicing.

Another subject matter of the invention relates to an electrical machine with at least or precisely one discharge device, as has already been described above or according to claims 1 to 7. In particular, the electrical machine is suitable and/or designed for a vehicle. The vehicle is preferably designed as an electric vehicle, in particular as a purely electric vehicle or as a hybrid vehicle. The vehicle can be designed as a one-lane or two-lane and/or one-axle or multi-axle vehicle, in particular a two-axle vehicle. In principle, the vehicle is designed as a passenger car, a truck or a bus. Alternatively, however, the vehicle can also be in the form of an electrically operated bicycle (pedelec), motorcycle (electric motorcycle), e-scooter or the like. The electric machine serves in particular to create and/or provide a traction torque, in particular a main traction torque, for the vehicle. For this purpose, the electrical machine can be coupled or coupled to an energy device, in particular to an energy storage device, in particular to a battery or accumulator, in order to obtain energy for generating the traction torque. The electrical machine is preferably designed as an electric motor.

In a specific embodiment, it is provided that the shaft has a shaft bore running coaxially to the main axis on the end face, the sleeve being held in the shaft bore, preferably in a non-positive manner. In particular, the shaft bore is designed as a blind hole. The sleeve, in particular the contact section and/or the sealing section, is preferably pressed into the shaft bore. Alternatively or optionally in addition, the housing section has a housing bore that runs coaxially to the main axis, with the grounding rod being held in the housing bore, in particular in a non-positive manner. In particular, the housing bore is designed as a through bore. The grounding rod, in particular the fastening section, is preferably screwed into the housing bore and/or secured in the housing bore via the fastening means. Optionally, the diverting device has a sealing element, with the fastening section being sealed off from the housing opening by the sealing element. In particular, the sealing element serves to seal the housing space against entry and/or exit of foreign particles. A diverting device is thus proposed which can be mounted in or on the shaft at the front in a particularly simple manner.

In a further specific implementation, it is provided that the housing space has a motor section which is designed and/or suitable for accommodating the rotor and stator. Furthermore, the housing space has a transmission section, which is designed and/or suitable for transmission-related connection of the shaft to a transmission device. The transmission device can be designed as a clutch device and/or as a shifting device and/or as a transmission device. The shaft is connected to the transmission device in terms of transmission technology, in particular the shaft forms an input shaft into the transmission device. For this purpose, the shaft can have a gear wheel section, for example, or can be firmly connected to a gear wheel. The gear wheel section can be formed, for example, by a toothing geometry arranged on the shaft. Alternatively, the gear wheel can be in the form of a gear wheel which is connected to the shaft in a torque-proof manner. Provision is preferably made for the motor section and the transmission section to be separated from one another via a separating section in the axial direction of the main axis, in particular in a dirt-tight and/or oil-tight manner. Preferably, the motor section and the gear section together form the housing space. The shaft is preferably passed through the separating section and sealed off from the separating section by a sealing element, e.g. another shaft sealing ring. The motor section is particularly preferably implemented as an oil area or as a dry area and the transmission section as an oil area.

According to this embodiment, it is provided that the diverting device is on an engine side of the Motor section is arranged. In particular, the diverting device is arranged at the end on the face of the shaft, which is arranged in the motor section and/or is guided out of it. Thus, the discharge device is arranged on the side of the rotor and installed where the electrical charge and/or electrical voltage is generated in the rotor, so that it can be discharged spatially close. Alternatively, the diverting device or optionally a further diverting device is arranged on a transmission side of the transmission section. In particular, the diverting device or the further diverting device is arranged at the end on the other end face of the shaft, which is arranged in the gear section and/or is guided out of it. The diverting device or the further diverting device is therefore arranged on the side of the transmission device, with this arrangement protecting the transmission section with the transmission device, so that any bearings in the transmission device do not suffer any damage from the passage of current.

• 1 eine schematische Schnittdarstellung einer elektrischen Maschine als ein Ausführungsbeispiel der Erfindung;
• 2 eine schematische Detailansicht der elektrischen Maschine aus 1 ;
• 3a, b unterschiedliche Darstellungen einer Ableitvorrichtung für die elektrische Maschine der 1 und 2.

Further features, advantages and effects of the invention result from the following description of preferred exemplary embodiments of the invention. It shows:

• 1 a schematic sectional view of an electrical machine as an embodiment of the invention;
• 2 a schematic detailed view of the electrical machine 1 ;
• 3a, b different representations of a discharge device for the electrical machine 1 and 2 .

1 shows an electrical machine 1 as an exemplary embodiment of the invention in a schematic sectional illustration. For example, the electric machine is designed and/or suitable for a vehicle, in particular an electric or hybrid vehicle. The electric machine 1 is designed as an electric traction machine and is used to generate and/or provide a traction torque, in particular a main traction torque, for the vehicle. The electrical machine 1 can be designed, for example, as a DC, synchronous or asynchronous motor, etc.

The electrical machine 1 has a rotor 2 and a stator 3 which are arranged coaxially and/or concentrically with respect to a main axis H with respect to one another. For example, the electrical machine 1 can be electrically connected to an energy device, e.g. a battery or an accumulator, in order to obtain energy for generating the traction torque.

Furthermore, the electric machine 1 has a shaft 4 for transmitting the traction torque. The rotor 2 is drivingly connected to the shaft 4 so that the shaft 4 is driven via and/or by the rotor 2 . The shaft 4 is thus designed as a rotor shaft and is mechanically, e.g. non-rotatably, and electrically connected to the rotor 2 for this purpose. The shaft 4 defines the main axis H with its axis of rotation.

The electrical machine 1 has a housing 5 which defines a housing space 6 . In the exemplary embodiment shown, the housing 5 is formed by the stator 3 and a housing section 7 and a further housing section 8 , the housing section 7 being arranged on one axial side and the further housing section 8 being arranged on the other axial side of the stator 3 . The housing space 6 is thus delimited in the radial direction by the stator 3 and in the axial direction by the two housing sections 7 , 8 .

The shaft 4 and the rotor 2 are rotatably mounted in the housing space 6 via a first and a second bearing device 9a, b. The two housing sections 7, 8 each form an end shield, with the shaft 4 being supported on the housing section 7 via the first bearing device 9a and on the further housing section 8 via the second bearing device 9b. In the exemplary embodiment shown, the bearing devices 9a, b are each designed as ball bearings, in particular deep groove ball bearings.

The housing space 6 is divided into a motor section 10 for accommodating the rotor 2 and a gear section 11 for connecting the shaft 4 to a gear device, not shown, with the motor section 10 and the gear section 11 being spatially separated from one another by a separating section 12 and via the shaft 4 are connected to one another in terms of transmission technology. For example, the separating section 12 is formed by the further housing section 8 or is also formed there.

For this purpose, the separating section 12 is arranged in the axial direction in relation to the main axis H between the motor section 10 and the transmission section 11 and is designed as a dividing wall. For example, the engine section 10 is formed as a dry section and the adjacent transmission section 11 as an oil section, with the partition section 12 forming an oil-tight partition between the engine section 10 and the transmission section 11 . For this purpose, the shaft 4 is guided from the motor section 10 through the separating section 12 into the transmission section 11 and is sealed off from the separating section 12 by a shaft sealing ring 13 .

The shaft 4 forms an input shaft into the transmission device. For this purpose, the electric machine 1 has a gear wheel 14 which is connected to the shaft 4 in a torque-proof manner and is arranged in the gear section 11 . The gear wheel 14 is designed as a gear wheel and can, for example, be in engagement with a further gear wheel, not shown, of the gear device in order to transfer the traction torque to the gear device.

During operation, damaging voltages can be induced onto the shaft 4 and thus into the rotor 2, as a result of which a capacitive coupling between the stator 3 and the rotor 2 arises. These stresses are usually dissipated via the bearing device 9a of the motor section 10 or partly also by the bearing device 9b of the transmission section 11. In addition, circulating high-frequency currents can arise in the electrical machine 1, particularly in the case of AC motors of high power classes. The circulating high-frequency currents circulate due to imbalances in the magnetic flux in the stator 3, for example through the bearing devices 9a, b of the electrical machine 1. As a result of the dissipation of the damaging voltages and the circulating high-frequency currents via the bearing devices 9a, b, bearing failures can occur . Sparks jump over the dielectric oil or grease film, also called spark erosion, between the rotating parts and the bearing raceway, causing melting craters and/or a type of bearing profiling (corrugation) in the bearing raceway of the bearing devices 9a, b.

In order to prevent the storage devices 9a, b from being damaged, this electrical energy must be dissipated. For this purpose, the electrical machine 1 has a discharge device 15 . The diverting device 15 serves to divert an electrical charge and/or electrical voltage, starting from the rotor 2 via the shaft 4 to the housing 5. The housing 5 is connected to ground and/or grounded, so that the electrical charges and/or voltages can be safely derived via the housing 5. For this purpose, the discharge device 15 is arranged on the motor side, in particular in the motor section 10, on an axial end face of the shaft 4 and is electrically connected to the shaft 4 on the one hand and to the housing 5, in particular the housing section 7, on the other hand.

the 2a FIG. 12 shows a detailed view of the motor section 10 with the diverter device 15 installed 1 . The diverting device 15 has a first and a second contact device 16, 17 which are arranged coaxially and/or concentrically with respect to the main axis H with respect to one another. The first contact device 16 is electrically and mechanically, in particular non-rotatably, connected to the shaft 4 and the second contact device 17 is electrically and mechanically, in particular non-rotatably connected to the housing section 7 . The two contact devices 16, 17 are mechanically decoupled from one another, so that the two contact devices 16, 17 can be rotated relative to one another, in particular when the electrical machine 1 is in operation.

Between the first and the second contact device 16, 17, a contact space 18 designed as an annular space is formed, via which the two contact devices 16, 17 are electrically connected to one another. For this purpose, the contact space 18 is filled with an electrically conductive liquid 19, the first and the second contact device 16, 17 being in electrically conductive contact with one another via the electrically conductive liquid 19. For example, the electrically conductive liquid is in the form of an electrically conductive oil, fat, liquid metal or ionic liquid. The contact space 18 is separated from the housing space 6 in a fluid-tight manner, so that the electrically conductive liquid 19 is prevented from escaping from the contact space 18 into the housing space 6 and foreign particles are prevented from entering the contact space 6 from the housing space 6 . Thus, an axially acting deflection device 15 is proposed, which can be used both in a dry and in a wet environment. Since the electrical contact between the first and the second contact device 16, 17 is established via the electrically conductive liquid 19, the discharge device 15 works with little friction and wear-free during operation of the electrical machine 1, so that no conductive abrasion can occur. Furthermore, the electrically conductive liquid 19 enables operation in any position, since the electrically conductive liquid 19 always ensures contact between the two contact devices 16, 17.

The first contact device 16 is designed as a sleeve 20 and the second contact device 17 as a grounding rod 21 . The sleeve 20 is designed as a metallic, in particular electrically conductive, cylindrical sleeve that is closed in an axial direction AR and is open in an opposite axial direction GR with respect to the main axis H. The grounding rod 21 is designed as a metallic, in particular electrically conductive, cylindrical rod, which is pushed so far into the sleeve 20 in the axial direction AR that the grounding rod 21 dips into the electrically conductive liquid 19 in sections. A direct contact between the grounding rod 21 (stator) and the sleeve 20 (rotor) is thus established via the electrically conductive liquid 19 . About this way of the least resistance, the induced currents are safely diverted to earth, so the currents are diverted away from the bearing through this system. The bearings of the connected assemblies, such as gears, etc., can also be protected in this way.

The discharge device 15 has a sealing device 22 , the grounding rod 21 being guided in a sealing manner in the sleeve 20 via the sealing device 22 . The sealing device 22 is arranged in front of the contact space 18 in the axial direction AR, with the grounding rod 21 being inserted in the axial direction via the sealing device 22 into the contact section 26 . In this case, the grounding rod 21 bears sealingly against the sleeve 20 via the sealing device 22 in the radial direction, so that the contact space 18 is sealed off in the opposite axial direction GR. The internal seal protects the contact space 18 from environmental influences that impair efficiency.

The housing section 7 has a first and a second housing part 7a, b, the two housing parts 7a, b being electrically and mechanically connected to one another. The first housing part 7a has a central housing opening 23, in particular arranged coaxially to the main axis H, through which the housing space 6 is accessible from the outside. The second housing part 7b is designed as a housing cover which closes the housing opening 23 . For example, the diverting device 15 can be mounted on the shaft 4 via the housing opening 23 and then connected to the housing section 7 . For this purpose, the second housing cover 7b can be mounted in the axial direction AR on the first housing cover 7a in a positive and/or non-positive manner, e.g. via a screw connection.

The shaft 4 has a shaft bore 24 arranged coaxially to the main axis H on the end face, the sleeve 20 being mounted in the shaft bore 24 in a form-fitting and/or force-fitting manner, in particular in a rotationally fixed manner. The second housing part 7b has a housing bore 25 arranged coaxially to the main axis H, with the grounding rod 21 being mounted in the housing bore 25 in a form-fitting and/or force-fitting manner, in particular non-rotatably, within the housing space 6 . The sleeve 20 thus makes direct contact with the shaft 4 and the grounding rod 21 makes direct contact with the housing section 7 .

3a shows the discharge device 15 in an exploded view. The sleeve 20 has a contact section 26 and a sealing section 27 , the contact section 26 forming the contact space 18 and the sealing section 27 forming a receptacle for the sealing device 22 . The sleeve 20 is designed as a shaped sheet metal component, with the contact section 26 and the sealing section 27 being formed by metal forming. The contact section 26 has a smaller diameter than the sealing section 27 , the sleeve 20 being pressed into the shaft bore 24 via the sealing section 27 . The grounding rod 21 is arranged in the contact section 26 at a distance from the sleeve 20 in the radial direction and in the axial direction in relation to the main axis H, the free space formed thereby being defined as the contact space 18 and filled with the electrically conductive liquid 19 completely or at least partially and /or is mostly filled.

The contact section 26 is closed in the axial direction AR and the sealing section 27 is open in the opposite axial direction GR, with the grounding rod 21 being guided into the contact section 26 via the sealing device 22 arranged in the sealing section 27 in a sealing manner. The sealing device 22 is embodied as a contacting rotary seal which rests sealingly on the one hand on an inner circumference of the sealing section 27 and on the other hand on an outer circumference of the grounding rod 21 . For this purpose, the sealing device 22 is designed as a cylindrical elastomer seal, which has a first and a second sealing lip 22a, b on its inner circumference. The two sealing lips 22a, b are spaced apart in the axial direction with respect to the main axis H and lie in the circumferential direction on the outer circumference of the grounding rod 21 in a sealing manner.

The sealing device 22 is held in the sealing section 27 in a positive and/or non-positive manner. In particular, the sealing device 22 bears against a radial shoulder 28 of the sleeve 20 in the axial direction AR, the sleeve 20 being tapered in the region of the shoulder 28 . The step 28 is formed in a transition area between the contact section 26 and the sealing section 27, the step 28 at the same time being able to form a radial stop for the grounding rod 21 in the event of an unsteady rotation.

Furthermore, the sleeve 20 has a form-fitting contour 29 on its inner circumference and the grounding rod 21 has a counter-contour 30 on its outer circumference, the form-fitting contour 29 engaging with the counter-contour 30 in order to secure the grounding rod 21 in the sleeve 20 against loss. The positive-locking contour 29 is formed by a collar pointing radially inward, and the counter-contour 30 by a groove, which is defined by two collars that are axially spaced apart and point radially outward. The collar of the form-fitting contour 29 engages in the groove of the counter-contour 30, so that the grounding rod 21 in the axial direction AR through one collar and in the axial opposite direction GR through the other collar of the counter-con tur 30 is secured. The grounding rod 21 is thus captively accommodated in the sleeve 20, so that the discharge device 15 can be offered as a preassembled structural unit.

At its free axial end, the grounding rod 21 has a fastening section 31, via which the grounding rod 21 is inserted into the housing bore 25, as shown in FIG 3b shown, can be mounted. For this purpose, the diverting device 15 has a fastening means 32 and a sealing element 33 , which can be mounted on the fastening section 31 at the end. During assembly, the grounding rod 21 is inserted with the fastening section 31 through the housing bore 25 and then secured via the fastening means 32 with the interposition of the sealing element 33 on the housing section 7, in particular the second housing part 7b. The counter-contour 30 , in particular the collar closest to the housing section 7 , can serve as a stop in the opposite axial direction GR for the grounding rod 21 . For example, the fastening section 31 has an external thread, with the fastening means 32 being designed as a screw nut and the sealing element 33 being designed as a sealing washer, with the sealing element 33 being pushed onto the fastening section 31 for assembly and the fastening means 32 being screwed onto the fastening section 31. A discharge device 15 is thus proposed which can be easily and inexpensively installed and easily replaced in the event of service.

Reference List

1

electric machine

2

rotor

3

stator

4

wave

4a, b

drilling

5

casing

6

housing space

7

housing section

7a, b

housing parts

8th

another housing section

9a, b

storage facilities

10

engine section

11

gear section

12

separation section

13

sealing organ

14

gear wheel

15

discharge device

16

first contact device

17

second contact device

18

contact space

19

electrically conductive liquid

20

sleeve

21

ground rod

22

sealing device

22a, b

sealing lips

23

case openings

24

shaft bore

25

housing bore

26

contact section

27

sealing section

28

paragraph

29

form-fitting contour

30

counter contour

31

attachment section

32

fasteners

33

sealing element

H

main axis

AR

axial direction

GR

axial opposite direction

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• JP2013174326A [0003]

Claims (10)

Dissipation device (15) for an electrical machine (1) for dissipating an electrical charge and/or voltage from a rotor (2) via a shaft (4) to a housing section (7), the housing section (7) having a housing space (6) limited, with a first contact device (16) for the electrical and mechanical connection to the shaft (4), with a second contact device (17) for the electrical and mechanical connection to the housing section (7), the first and the second contact device (16, 17) can be rotated relative to one another about a main axis (H) and are electrically connected to one another in a contact space (18) sealed off from the housing space (6), characterized in that the contact space (18) is filled with an electrically conductive liquid (19). is, wherein the first and the second contact device (16, 17) are electrically conductively connected to one another via the electrically conductive liquid (19). Drainage device (15) after claim 1 , characterized in that one contact device (16) is designed as a sleeve (20) and the other contact device (17) as a grounding rod (21), the sleeve (20) having the contact space (18) with the electrically conductive liquid ( 19) and wherein the grounding rod (21) is arranged in sections in the sleeve (20) so that the grounding rod (21) dips into the electrically conductive liquid (19) in the contact space (18). Drainage device (15) after claim 2 , characterized in that the sleeve (20) has a sealing section (27) for receiving a sealing device (22) and a contact section (26) adjoining the sealing section (27) to form the contact space (18), the earthing rod (21 ) is guided in a sealing manner via the sealing section (27) into the contact section (26). Drainage device (15) after claim 3 , characterized by a sealing device (22) for sealing the contact space (18), wherein the sealing device (22) is accommodated in the axial direction in relation to the main axis (H) in a form-fitting and/or force-fitting manner in the sealing section (27), the Grounding rod (21) via the sealing device (22) is sealingly supported on an inner circumference of the sleeve (20). Drainage device (15) after claim 4 , characterized in that the sealing device (22) is designed as a rotary seal, the sealing device (22) having at least one sealing lip (22a, b), the at least one sealing lip (22a, b) on an outer circumference of the grounding rod (21) starts radially. Drainage device (15) according to one of claims 2 until 5 , characterized in that the sleeve (20) has a form-fitting contour (29) on its inner circumference and the grounding rod (21) has a counter-contour (30) on its outer circumference, the form-fitting contour (29) and the counter-contour (30) engaging with one another , so that the grounding rod (31) is secured against losing it in the sleeve (20). Diverting device (15) according to one of the preceding claims, characterized in that the second contact device (17) has a fastening section (31) at the end, the diverting device (15) having a fastening means (32) for detachably fastening the fastening section (31) to the housing section (7) has. Electrical machine (1) with a housing section (7), with the housing section (7) delimiting a housing space (6), with a rotor (2) and with a shaft (4), with the shaft (4) being connected to the rotor (2 ) is connected electrically and in terms of transmission technology and wherein the shaft (4) and the rotor (2) are rotatably mounted in the housing space (6), the shaft (4) defining a main axis (H), characterized by at least one diverting device (15 ) according to any one of the preceding claims. Electrical machine (1) according to claim 8 , characterized in that the shaft (4) has a shaft bore (24) running coaxially to the main axis (H) on the front side, the sleeve (20) being held in the shaft bore (24) and/or that the housing section (7) has a has a housing bore (25) running coaxially to the main axis (H), the earthing rod (21) being held in the housing bore (25). Electrical machine (1) according to claim 8 or 9 , characterized in that the housing space (6) has a motor section (10) for accommodating the rotor (2) and a transmission section (11) for the transmission connection of the shaft (4) to a transmission device, with the diverting device (15) being optionally on a Motor side of the motor section (10) or on a transmission side of the transmission section (11) is arranged.

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