Power transmission assembly, rotating electric machine, and method for transmitting an electric excitation current

Abstract

The invention relates to a power transmission assembly comprising a power transmission device (84) for a rotating electric machine, in particular a synchronous machine, for transmitting an electric excitation current to a slip ring (85) which can be arranged on the shaft of a rotor of the machine, wherein the power transmission device comprises the slip ring, and the power transmission device comprises at least one contact element (86, 87, 88), preferably a contact element designed as a brush, for contacting the slip ring such that a sliding contact surface of the contact element can be contacted by a circumferential contact surface of the slip ring in order to form an electrically conductive sliding contact between the sliding contact surface and the circumferential contact surface. The power transmission assembly comprises an oiling device (89) for oiling the sliding contact surface and / or the circumferential contact surface with an oil-type fluid, preferably in a continuous manner, during the operation of the machine. The contact element is made of a first carbon material, preferably a copper-free carbon material, and the circumferential contact surface is made of a second carbon material, a preferably copper-free carbon material.

Description

[0001] Power transmission arrangement, rotating electrical machine and method for transmitting an electrical excitation current

[0002] The invention relates to a power transmission arrangement, comprising a power transmission device for a rotating electrical machine, in particular a synchronous machine, for transmitting an electrical excitation current into a slip ring that can be arranged on a shaft of a rotor of the machine, and a method for transmitting an electrical excitation current into a slip ring arranged on a shaft of a rotor of a rotating electrical machine, in particular a synchronous machine, wherein the power transmission device comprises at least one contact element, preferably designed as a brush, for contacting the slip ring, such that a sliding contact surface of the contact element can be contacted with a circumferential contact surface of the slip ring to form an electrically conductive sliding contact between the sliding contact surface and the circumferential contact surface.The invention further relates to a rotating electrical machine, in particular a synchronous machine, comprising a power transmission arrangement. A power transmission arrangement or power transmission device of the type initially described is well known in the prior art and is regularly used to transmit an electrical excitation current to a slip ring arranged on a rotor shaft of a current-excited or separately excited synchronous machine. From the slip ring, the excitation current then flows into an excitation winding of the rotor, which is electrically connected to the slip ring and serves to generate a magnetic excitation field.

[0003] The power transmission device typically comprises at least one contact element, usually designed as a brush, for contacting the slip ring, such that a sliding contact surface of the contact element can be contacted with a circumferential contact surface of the slip ring to form an electrically conductive sliding contact between the sliding contact surface and the circumferential contact surface. The power transmission device known from the prior art is always designed as a dry-running device, i.e., it runs without lubrication with a lubricant. This results in increased wear of the sliding contact surface and the circumferential contact surface due to increased friction between the sliding contact surface and the circumferential contact surface, which disadvantageously shortens the service life of the power transmission device or the slip ring.In addition, the dry-running power transmission device, if integrated into a gearbox, for example, requires a corresponding sealing system to protect the installation space against oil contamination. This sealing system requires additional installation space and causes additional friction losses. The presence of the sealing system therefore results in increased mass and increased friction, which disadvantageously reduces the efficiency of the machine or gearbox into which the machine may be integrated. Furthermore, the dry-running power transmission device requires a ventilation system to dissipate heat, particularly resulting from the friction between the sliding contact surface and the circumferential contact surface. This requires additional installation space and further disadvantageously reduces the efficiency of the machine or gearbox.

[0004] The present invention is therefore based on the object of proposing a power transmission arrangement, a rotating electrical machine and a method for transmitting an electrical excitation current, which has or enables an increased service life, a reduced installation space and an increased efficiency.

[0005] This object is achieved by a current transmission arrangement having the features of claim 1, a rotating electrical machine having the features of claim 16 and a method for transmitting an electrical excitation current having the features of claim 18.

[0006] The power transmission arrangement according to the invention comprises a power transmission device for a rotating electrical machine, in particular a synchronous machine, for transmitting an electrical excitation current into a slip ring that can be arranged on a shaft of a rotor of the machine, wherein the power transmission device comprises the slip ring, wherein the power transmission device comprises at least one contact element, preferably designed as a brush, for contacting the slip ring in such a way that a sliding contact surface of the contact element can be contacted with a circumferential contact surface of the slip ring to form an electrically conductive sliding contact between the sliding contact surface and the circumferential contact surface, wherein the power transmission arrangement comprises a lubrication device for, preferably continuously, lubrication of the sliding contact surface and / or the circumferential contact surface with an oily fluid during operation of the machine.The current transmission arrangement or current transmission device according to the invention is designed to transmit an electrical excitation current to a slip ring that can be arranged or is arranged on a shaft of a rotor of a rotating electrical machine, in particular a current-excited or separately excited synchronous machine. From the slip ring, the excitation current can then flow into an excitation winding of the rotor that is electrically conductively connected to the slip ring and can serve to generate a magnetic excitation field. The current transmission device comprises at least one contact element, preferably designed as a brush, for contacting the slip ring in such a way that a sliding contact surface of the contact element can be contacted with a circumferential contact surface of the slip ring to form an electrically conductive sliding contact between the sliding contact surface and the circumferential contact surface.The term “circumferential contact surface” is understood to mean a raceway, preferably in the form of a strip, which runs around the outer circumference of the slip ring in a circumferential direction of the slip ring.

[0007] The power transmission arrangement further comprises a lubrication device for the preferably continuous lubrication of the sliding contact surface and / or the circumferential contact surface with an oily fluid during operation of the machine. The lubrication device can be a component of the power transmission device or the machine, or an external lubrication device formed separately from the power transmission device and the machine. According to the invention, the power transmission arrangement or power transmission device is therefore designed as a wet rotor. The discharge of the oily fluid onto the sliding contact surface and / or the circumferential contact surface effects lubrication, so that friction between the sliding contact surface and the circumferential contact surface is reduced, which in turn results in reduced wear on the sliding contact surface and the circumferential contact surface, thereby extending the service life of the power transmission arrangement or power transmission device.of the slip ring is advantageously increased. Furthermore, the release of the oily fluid onto the sliding contact surface and / or the circumferential contact surface advantageously carries away heat resulting in particular from the friction between the sliding contact surface and the circumferential contact surface, so that a ventilation device can be dispensed with, thereby saving installation space and advantageously increasing the efficiency of a machine or a transmission into which the machine can be integrated. Furthermore, because the power transmission arrangement or power transmission device is designed as a wet rotor, if the power transmission arrangement or power transmission device is integrated, for example, in a transmission, a corresponding sealing system for protecting an installation space against oil contamination can be dispensed with, thereby advantageously saving further installation space and further increasing the efficiency of the machine or transmission.Nevertheless, the power transmission arrangement or power transmission device may comprise a sealing device for protecting a region of a power transmission from the oily fluid, which, however, in comparison to the sealing system, only insignificantly influences the installation space and the efficiency of the machine or a transmission into which the machine may be integrated.

[0008] According to the invention, the power transmission device comprises the slip ring. The power transmission device can comprise at least one slip ring or a plurality of slip rings that can be arranged on the shaft. Each slip ring can then have a circumferential contact surface.

[0009] According to the invention, the contact element is made of a first carbon material, preferably copper-free, or based on graphite, preferably

[0010] - polymer-bonded graphite, preferably with a graphite content of at least 80% by mass, preferably with polyphenylene sulfide (PPS) as polymer, - hard-fired graphite or carbon graphite or hard-fired carbon, preferably with a graphite content of at least 70% by mass, or

[0011] - a silver-graphite mixture, preferably with a silver content of 30% to 80% by mass. The contact element can also be made of another resin-bonded carbon material or another metal-carbon mixture, in particular a metal-graphite mixture. The graphite can be natural graphite, synthetic graphite, or electrographite. Furthermore, the carbon material can contain coke, in particular mineral coke, cleaning agents, and / or carbon fibers. The contact element is preferably free of copper, since copper regularly erodes under prolonged stress. Copper also regularly causes additional chemical or catalytic reactions with the oily fluid, as a result of which relevant physical properties of the oily fluid, for example, lubricity or viscosity, can be negatively affected.To avoid these adverse effects, the contact element can therefore be designed free of copper, at least in the area of ​​the sliding contact surface. In an area away from the sliding contact surface, the contact element can also contain copper for improved electrical contact with a cable, in particular a stranded wire. With the same in mind, the contact element can also be designed free of aluminum and / or steel.

[0012] According to the invention, the circumferential contact surface or the slip ring in a region of the circumferential contact surface or a contact ring of the slip ring is made of a, preferably copper-free, second carbon material or based on graphite, preferably

[0013] - Electrographite, preferably with a density of 1.55 g / cm 3 up to 2.1 g / cm 3, preferably with an open porosity of 5% to 20%, preferably with a flexural strength of at least 15 MPa,

[0014] - polymer-bonded graphite, preferably with a density of 1.55 g / cm 3 up to 2.1 g / cm 3 , preferably with an open porosity of 5% to 15%, preferably with a flexural strength of at least 15 MPa,

[0015] - Hard-fired graphite or carbon graphite or hard-fired coal, preferably with a density of 1.55 g / cm 3 up to 3.0 g / cm 3 , preferably with an open porosity of 5% to 20%, preferably with a flexural strength of at least 15 MPa, or

[0016] - a metal-graphite mixture, preferably with a density of 2.3 g / cm 3 up to 4.8 g / cm 3, preferably with an open porosity of 5% to 15%, preferably with a flexural strength of at least 15 MPa, preferably with a metal content of at least 25% by mass. The proportion of graphite in the polymer-bound graphite can be at least 80% by mass. Polyphenylene sulfide (PPS) can be provided as the polymer. Furthermore, the proportion of graphite in the hard-fired graphite can be at least 70% by mass. Furthermore, silver, for example, can be provided as the metal in the metal-graphite mixture. The circumferential contact surface can also be made of another synthetic resin-bonded carbon material. Natural graphite, synthetic graphite or electrographite can be provided as the graphite. Furthermore, the carbon material can contain coke, in particular mineral coke, cleaning agents and / or carbon fibers. The circumferential contact surface or the slip ring is preferably in the region of the circumferential contact surface orthe contact ring is designed free of added copper, since copper regularly erodes under prolonged stress. Copper also regularly causes additional chemical or catalytic reactions with the oily fluid, as a result of which relevant physical properties of the oily fluid, for example lubricity or viscosity, can be negatively influenced. In order to avoid these disadvantageous effects, the circumferential contact surface or the slip ring can be designed free of added copper, at least in the area of ​​the circumferential contact surface, or the contact ring can be designed free of added copper, at least in the area of ​​the circumferential contact surface. In an area away from the circumferential contact surface, the slip ring or the contact ring can in principle also contain copper for improved electrical contact with a connection or a cable. Against the same background, the circumferential contact surface orthe slip ring must be free of aluminum and / or steel at least in the area of ​​the circumferential contact surface or the contact ring at least in the area of ​​the circumferential contact surface.

[0017] The statements made with regard to the first carbon material of the circumferential contact surface or the slip ring in the region of the circumferential contact surface or the contact ring can be partially or completely transferred to the second carbon material of the contact element, and vice versa. In particular, the first carbon material can also be identical to the second carbon material.

[0018] The material pairings listed above for the contact element on the one hand and the circumferential contact surface or the slip ring in the area of ​​the circumferential contact surface or the contact ring on the other hand prevent not only chemical or catalytic reactions with the oily fluid, but also electrochemical attacks on the sliding contact partners, i.e. the contact element and the slip ring or the circumferential contact surface or the contact ring.

[0019] Lubrication can take place across the entire speed range of the machine.

[0020] Advantageously, the contact element, which is preferably rod-shaped, can have the sliding contact surface on the front side.

[0021] A longitudinal axis of the contact element can extend transversely to a longitudinal axis of the shaft or a rotational axis of the slip ring. The longitudinal axis or an extension of the longitudinal axis in the direction of the slip ring can run through the rotational axis of the slip ring or the longitudinal axis of the shaft.

[0022] The contact element can, for example, have a circular, square or rectangular cross-section.

[0023] Advantageously, the slip ring can have a plurality of circumferential contact surfaces, preferably at least two circumferential contact surfaces, in particular two or three circumferential contact surfaces. The circumferential contact surfaces can be spaced apart from one another, preferably at equal intervals or equidistantly, viewed in the direction of the rotational axis of the slip ring, and can run parallel to one another. Each circumferential contact surface can then be assigned to a phase.

[0024] Advantageously, the slip ring can comprise a carrier sleeve made of an electrically insulating material, preferably a polymer, and at least one contact ring arranged on the carrier sleeve, which contact ring can be made of an electrically conductive material. The contact ring can have the circumferential contact surface, preferably on the outer circumference. The carrier sleeve can form a recess or a passage into which the shaft can engage or through which the shaft can pass in order to arrange the slip ring on the shaft. The carrier sleeve can be manufactured by injection molding. Furthermore, the slip ring can comprise, preferably on the inner circumference, at least one connection for the excitation winding arranged on the contact ring or at least one line, in particular a stranded wire, which at one end, preferably on the inner circumference, is electrically conductively connected to the contact ring and at the other end can be electrically conductively connected to the excitation winding.If the slip ring comprises multiple contact rings and thus has multiple circumferential contact surfaces, the connections or lines of the slip ring assigned to different phases can be arranged at a maximum distance or angle from each other on the slip ring or contact ring, viewed in the circumferential direction of the slip ring. For example, the connections or lines can be offset from each other by an angle of 180° for two phases and by an angle of 120° for three phases.

[0025] Advantageously, the power transmission device can comprise at least one spring element, by means of which the sliding contact surface is pressed against the peripheral contact surface, preferably with a contact pressure of 7 N / cm 2 up to 35 N / cm 2, to ensure optimized contact and the formation of a uniform film of oily fluid. The spring element can be a spiral or roller spring, which exhibits a low force loss over a travel. However, it is also conceivable to provide a helical spring as the spring element. The contact pressure in the aforementioned area can reliably prevent the contact element from floating on the film or oil planing, which can lead to a loss of electrical contact between the contact element and the slip ring.

[0026] Advantageously, the power transmission device may comprise a plurality of contact elements.

[0027] Advantageously, the plurality of contact elements can be configured such that, of a plurality of circumferential contact surfaces of the slip ring, each circumferential contact surface can be contacted by means of at least one contact element of the plurality of contact elements or a respective sliding contact surface. In other words, a number of the contact elements can correspond to at least a number of the circumferential contact surfaces. In one embodiment of the power transmission arrangement or power transmission device, the power transmission device can comprise at least a first contact element for contacting a first circumferential contact surface of the slip ring and a second contact element for contacting a second circumferential contact surface of the slip ring. The plurality of circumferential contact surfaces can in principle also be provided by a plurality of slip rings that can be arranged on the shaft.Advantageously, the plurality of contact elements can be configured such that the circumferential contact surface or each circumferential contact surface can be contacted by means of at least two or two or at least three contact elements of the plurality of contact elements or a respective sliding contact surface. Accordingly, at least two contact elements, in particular two or three contact elements, can be provided for the circumferential contact surface or for each circumferential contact surface. In one embodiment of the current transmission arrangement or current transmission device, the current transmission device can comprise at least two first contact elements for contacting a first circumferential contact surface of the slip ring and at least two second contact elements for contacting a second circumferential contact surface of the slip ring. The provision of a plurality of contact elements contacting a circumferential contact surface enables the transmission of a higher excitation current.In addition, hydrodynamic effects can be avoided and uniform oiling can be achieved.

[0028] Advantageously, the power transmission device can be designed such that the two or at least three contact elements of the plurality of contact elements, when the power transmission device or slip ring is arranged on the machine, are distributed only along a portion of the circumference of the slip ring or the circumferential contact surface. Dry running can thereby be advantageously prevented. Furthermore, the power transmission device or slip ring can thus advantageously be arranged or mounted laterally on the machine or shaft and does not require a complex installation over the shaft or rotor.

[0029] Advantageously, the central angle of a circular arc defined by the part can be between 55° and 170°. The central angle can also be between 90° and 170°. In other words, the central angle is the angle between the two outermost contact elements.

[0030] Depending on the embodiment of the power transmission arrangement or power transmission device, distances between each two adjacent contact elements of the at least three contact elements of the plurality of contact elements viewed in a circumferential direction of the slip ring can all be the same size, partially different sizes or different sizes in pairs.

[0031] Advantageously, the power transmission device can comprise a holding device in which the contact element can be guided, preferably radially or movably in a radial direction of the slip ring.

[0032] In one embodiment of the power transmission arrangement or power transmission device, the holding device can comprise a holding part made of an electrically conductive material, preferably metal, in which the contact element can be guided, wherein the contact element can be electrically conductively connected to the holding part forming a busbar of the power transmission device by means of a line, preferably a stranded wire, of the power transmission device. Thus, the holding part can simultaneously function as a busbar. The holding part can be produced by stamping. Preferably, the holding part can be formed as a metal stamped part. The line can be pressed or stamped into the contact element at one end and welded, soldered, or mechanically connected, in particular clamped or crimped, to the holding part at the other end.If the power transmission device comprises a plurality of contact elements, each with a sliding contact surface for contacting a plurality of circumferential contact surfaces, the holding device can comprise a carrier part made of an electrically insulating material, in particular a polymer, in order to electrically separate the contact elements contacting different circumferential contact surfaces or associated with different phases. For example, the holding device can then comprise a holding part for each circumferential contact surface or phase, wherein the holding parts can be arranged on the carrier part.

[0033] In an alternative embodiment of the power transmission arrangement or power transmission device, the holding device can be formed from an electrically insulating material, preferably polymer and / or ceramic, wherein the power transmission device can comprise a busbar arranged on or in the holding device, wherein the contact element can be electrically connected to the busbar by means of a line, preferably a stranded wire, of the power transmission device. The holding device can be manufactured by injection molding. The line can be pressed or stamped into the contact element at one end and welded, soldered, or mechanically connected, in particular clamped or crimped, to the busbar at the other end.

[0034] Advantageously, the power transmission device can include the lubrication device. Accordingly, the lubrication device can be a component of the power transmission device or formed integrally with the power transmission device. Alternatively, the lubrication device can be included in the machine or be an external lubrication device formed separately from the power transmission device or machine.

[0035] Advantageously, the lubrication device can have at least one channel for the oily fluid. The oily fluid can then be discharged via an outlet opening, in particular at the end, of the channel. The channel can be arranged in the holding device. Alternatively, the channel can also be formed by the holding device or the contact element. If there are a plurality of circumferential contact surfaces, the channel preferably has only one outlet opening per circumferential contact surface. The channel can form a branch, in particular a fork, in order to distribute the oily fluid to the individual circumferential contact surfaces if there are a plurality of circumferential contact surfaces. It is also conceivable for the channel to have an outlet opening for each contact element if there are a plurality of contact elements.

[0036] Advantageously, the contact element can be manufactured by pressing and subsequent heat treatment, whereby the power transmission device can be designed such that, when the power transmission arrangement or device is arranged on the machine, the contact element can be pressed axially relative to a longitudinal axis of the shaft. This can increase the service life of the contact element or power transmission device.

[0037] An excitation current that can be transmitted by means of the current transmission device can have a current strength of up to 40 A.

[0038] The excitation current can be transmitted continuously or as a permanent current.

[0039] Further advantageous embodiments of the current transmission arrangement according to the invention emerge from the descriptions of the features of the subclaims referring back to method claim 18.

[0040] The rotating electrical machine according to the invention, in particular a current-excited or separately excited synchronous machine, comprises a current transmission arrangement according to the invention.

[0041] A power transmission device of the power transmission arrangement can be provided for transmitting an electrical excitation current to a slip ring arranged on a shaft of a rotor of the machine. The rotor can comprise an excitation winding electrically connected to the slip ring for generating a magnetic excitation field. The machine can comprise a lubrication device of the power transmission device. Accordingly, the lubrication device can be a component of the machine or formed integrally with the machine. For example, the lubrication device can be designed such that lubrication takes place via the shaft.

[0042] In the method according to the invention for transmitting an electrical excitation current into a slip ring arranged on a shaft of a rotor of a rotating electrical machine, in particular a synchronous machine, the slip ring is contacted by means of at least one contact element, preferably designed as a brush, of a current transmission device, such that a sliding contact surface of the contact element is contacted with a circumferential contact surface of the slip ring to form an electrically conductive sliding contact between the sliding contact surface and the circumferential contact surface, wherein the sliding contact surface and / or the circumferential contact surface is lubricated with an oily fluid by means of a lubrication device during operation of the machine, preferably continuously.

[0043] The power transmission device and the lubrication device can be part of a power transmission arrangement.

[0044] For the advantageous effects of the method according to the invention, reference is made to the description of advantages of the power transmission arrangement according to the invention.

[0045] In the method, the contact element can be formed from the first carbon material according to the corresponding features of patent claim 1 and / or the circumferential contact surface can be formed from the second carbon material according to the corresponding features of patent claim 1. In this context, reference is made to the corresponding feature description. However, the contact element and / or the circumferential contact surface can also be formed from another suitable material in the method. In the method, the power transmission device can comprise the slip ring. If the power transmission device does not comprise the slip ring in the method, the machine can comprise the slip ring.

[0046] The lubrication device can be part of the power transmission device. Alternatively, the lubrication device can be part of the machine or an external lubrication device designed separately from the power transmission device and the machine, particularly if the oily fluid is distributed via the shaft.

[0047] Advantageously, the oil-like fluid used can be engine oil and / or gear oil, preferably with a kinematic viscosity of 10 mm 2 / s up to 30 mm 2 / s at a reference temperature of 40 °C, which is regularly present in a motor or gearbox in which the power transmission arrangement or power transmission device can be integrated.

[0048] Advantageously, the oily fluid can be delivered to the sliding contact surface and / or the peripheral contact surface at a flow rate of 10 ml / min to 1000 ml / min. The flow rate can be varied depending on the machine's power or speed. The flow rate can be generated or adjusted by means of a pump, in particular an oil pump, of the machine.

[0049] Advantageously, the oily fluid can be dispensed in an upper region or upper half of the slip ring. In particular, the lubrication device, particularly when it is a component of the power transmission device, can be designed such that when the power transmission arrangement or power transmission device or slip ring is arranged on the machine, the oily fluid can be dispensed in the upper region or upper half of the slip ring. The “upper region” is understood to mean an area from 9:00 a.m. to 3:00 a.m. of the slip ring. Due to gravity, the oily fluid can then be distributed from above, in particular over the circumferential contact surface. For example, the oily fluid can be dispensed centrally above the slip ring, i.e. at 12:00 p.m. of the slip ring. The used oily fluid can then be transported away in a lower region ora lower half of the slip ring, i.e. in an area from 3:00 o'clock to 9:00 o'clock of the slip ring, in particular as a result of gravity and / or a centrifugal force.

[0050] Advantageously, the oily fluid can be dispensed onto the sliding contact surface and / or the circumferential contact surface exclusively upstream of the contact element in the direction of rotation of the slip ring in order to enable optimal lubrication. In particular, the lubrication device, particularly if it is a component of the power transmission device, can be designed such that the oily fluid can be dispensed onto the sliding contact surface and / or the circumferential contact surface exclusively upstream of the contact element in the direction of rotation of the slip ring in order to enable optimal lubrication while simultaneously enabling a simple design of the power transmission arrangement or power transmission device. Insofar as the power transmission device comprises a plurality of contact elements for contacting the circumferential contact surface, the oily fluid can be dispensed exclusively upstream of the first contact element in the direction of rotation.It is also conceivable, however, to dispense the oily fluid in front of several or even all of these contact elements. If there are a plurality of circumferential contact surfaces, the oily fluid can be dispensed for each circumferential contact surface exclusively in front of a respective first contact element which, viewed in the direction of rotation, contacts a respective circumferential contact surface. If the slip ring or the machine can rotate in two directions of rotation, the direction of rotation is to be understood as a preferred direction of rotation or forward direction of rotation. Since, when the slip ring or the machine rotates in a reverse direction of rotation, i.e. opposite to the preferred direction of rotation orSince only low speeds regularly occur in the forward rotation direction, and the operating time of the machine in the reverse rotation direction is typically only a few percent of the total operating time of the machine, the service life of the power transmission arrangement or power transmission device is only insignificantly affected by the provision of the oily fluid only upstream of the contact element. In principle, however, it is also conceivable to discharge the oily fluid onto the sliding contact surface and / or the circumferential contact surface upstream and downstream of the contact element, as viewed in the direction of rotation of the slip ring.

[0051] The oily fluid can be discharged onto the sliding contact surface and / or the circumferential contact surface through at least one outlet opening formed in the shaft and / or the slip ring and / or the contact element.

[0052] Further advantageous embodiments of the method according to the invention emerge from the feature descriptions of the subclaims referring back to device claim 1.

[0053] Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawings.

[0054] They show:

[0055] Fig. 1 is a partial view of a power transmission device in a first embodiment;

[0056] Fig. 2 is a partial view of a power transmission device in a second embodiment;

[0057] Fig. 3 is a cross-sectional view of a slip ring of a power transmission device; Fig. 4 is a partial longitudinal sectional view of the slip ring of the power transmission device;

[0058] Fig. 5 is a partial cross-sectional view of a power transmission device in a third embodiment;

[0059] Fig. 6 is a partial cross-sectional view of a power transmission device in a fourth embodiment;

[0060] Fig. 7 is a partial cross-sectional view of a power transmission device in a fifth embodiment;

[0061] Fig. 8 is a partial longitudinal sectional view of a power transmission device in a sixth embodiment;

[0062] Fig. 9 is a partial cross-sectional view of a power transmission device in a seventh embodiment.

[0063] Figs. 1 to 9 are schematic and illustrate various aspects of the invention based on various embodiments. These are predominantly partial views, in which the components to be emphasized in the respective embodiment are shown or provided with reference numerals. The remaining components are not shown or provided with reference numerals for the sake of simplicity.

[0064] Fig. 1 shows a power transmission device 10, comprising a slip ring 11 and two rod-shaped contact elements 14, 15 arranged along a part 12 of a circumference 13 of the slip ring 11 for contacting the slip ring 11, such that a respective end-side sliding contact surface 16, 17 of the contact elements 14, 15 can be contacted with a circumferential contact surface 18 of the slip ring 11 to form a respective electrically conductive sliding contact between the respective sliding contact surface 16, 17 and the circumferential contact surface 18. The contact elements 14, 15 extend with a respective longitudinal axis 19, 20 of the contact elements 14, 15 transversely to a rotational axis 21 of the slip ring 11, wherein the respective longitudinal axis 19, 20 extends through the rotational axis 21. Viewed in a circumferential direction 22 of the slip ring 11, the two contact elements 14, 15 are at an angle y xarranged at a distance from one another, wherein the angle yt is measured between the longitudinal axes 19, 20. Furthermore, the contact elements 14, 15 are each prestressed radially against the slip ring 11 by a spring element 23, 24 of the power transmission device 10 in directions indicated by arrows 25, such that the sliding contact surfaces 16, 17 are pressed against the circumferential contact surface 18. The power transmission device 10 comprises two further contact elements, each prestressed by a spring element of the power transmission device 10, which, since they are located behind the contact elements 14, 15 orSpring elements 23, 24 are arranged, not visible, for contacting a further circumferential contact surface of the slip ring 11, which is located behind the circumferential contact surface 18 when viewed in the direction extending into the plane of the drawing and is therefore not visible, and is spaced from the circumferential contact surface 18. The further contact elements are designed and arranged like the contact elements 14, 15. The further circumferential contact surface is also designed like the circumferential contact surface 18.

[0065] Fig. 2 shows a power transmission device 26, comprising a slip ring 27 and three rod-shaped contact elements 30, 31, 32 arranged along a part 28 of a circumference 29 of the slip ring 27 for contacting the slip ring 27. Viewed in a circumferential direction 33 of the slip ring 27, the two contact elements 30, 31 are arranged at an angle α and the two contact elements 31, 32 are arranged at an angle β from one another. The two outer contact elements 30, 32 are arranged at an angle γ from one another, viewed in the circumferential direction 33, which corresponds to a sum of the angle α and the angle β. The angles α, β, γ are each measured between longitudinal axes 34, 35, 36 of the contact elements 30, 31, 32. Part 28 defines a circular arc 37, where the angle y2 corresponds to a central angle of the circular arc 37.The distances between the angles α, β defining the contact elements 30, 31 and 31, 32 are different in this case. In principle, however, they can also be the same. The current transmission device 26 comprises three further contact elements, which are not visible because they are arranged behind the contact elements 30, 31, 32 when viewed in a direction extending into the plane of the drawing. The further contact elements are designed and arranged like the contact elements 30, 31, 32.

[0066] 3 and 4 together show a slip ring 38 of a power transmission device (not shown in detail here), which comprises a carrier sleeve 39 made of an electrically insulating material and three contact rings 40, 41, 42 arranged on the carrier sleeve 39 and made of an electrically conductive material, wherein the contact rings 40, 41, 42 each have a circumferential contact surface 43, 44, 45 on their outer circumference. The carrier sleeve 39 forms a passage 46 through which a shaft (not shown here) of a rotor (not shown here) of a rotating electrical machine (not shown here) can pass, in order to arrange the slip ring 38 on the shaft. The circumferential contact surfaces 43, 44, 45 are spaced apart from one another at equal intervals as viewed in the direction of a rotational axis 47 of the slip ring 38 and run parallel to one another. Each circumferential contact surface 43 , 44, 45 respectively.Each contact ring 40, 41, 42 is assigned to a phase. Furthermore, the slip ring 38 comprises two lines 48, 49 and 50, 51 and 52, 53 for each circumferential contact surface 43, 44, 45 or contact ring 40, 41, 42 or phase, which are electrically connected at one end to the inner circumference of the respective contact ring 40, 41, 42 and at the other end can be electrically connected to an excitation winding of the rotor (not shown here). Fig. 5 shows a power transmission device 54 with a holding device 55, which comprises a holding part 56 made of an electrically conductive material, in which two contact elements 57, 58 of the power transmission device 54 are guided. The contact elements 57, 58 are each electrically connected to the holding part 56 by means of a line 59, 60 of the power transmission device 54. Thus, the holding part 56 forms a busbar 61 of the power transmission device 54.The holding device 55 further comprises a carrier part 62 formed from an electrical insulating material, wherein the holding part 56 is arranged on the carrier part 62.

[0067] Fig. 6 shows a power transmission device 63 with a holding device 64 which is formed from an electrical insulating material, wherein the power transmission device 63 comprises a busbar 65 arranged in the holding device 64, wherein two contact elements 66, 67 of the power transmission device 63 are electrically conductively connected to the busbar 65 by means of a line 68, 69 of the power transmission device 63.

[0068] Fig. 7 shows a power transmission device 70 with two contact elements 72, 73 guided in a holding device 71 of the power transmission device 70. The contact elements 72, 73 contact a circumferential contact surface 75 of a slip ring 76 of the power transmission device 70. The power transmission device 70 further comprises a lubrication device 78 for lubricating the circumferential contact surface 75 with an oily fluid. The lubrication device 78 has a channel 79 for the oily fluid arranged in the holding device 71, which channel has an outlet opening 81 from which the oily fluid can be discharged in front of the first contact element 73, as viewed in a direction of rotation 83 of the slip ring 76. The power transmission device 70 and the lubrication device 78 form a power transmission arrangement or are comprised by the power transmission arrangement. Fig. 8 shows a current transmission device 94 with two contact elements 95, 96.The contact element 95 contacts a first circumferential contact surface 97 of a slip ring 98 of the power transmission device 94, while the contact element 96 contacts a second circumferential contact surface 99 of the slip ring 98. The power transmission device 94 further comprises a lubrication device 100 for lubricating the circumferential contact surfaces 97, 99 with an oily fluid. The lubrication device 100 has a channel 101 for the oily fluid, which has a fork 102 to distribute the oily fluid over the circumferential contact surfaces 97, 99. For each circumferential surface 97, 99, the channel 101 has an outlet opening 103, 104, from which the oily fluid can be discharged in front of the contact element 95, 96, viewed in a rotation direction of the slip ring 98 (not shown here). The power transmission device 94 and the lubrication device 100 form a power transmission arrangement or are comprised by the power transmission arrangement.

[0069] Fig. 9 shows a power transmission device 84 comprising a slip ring 85, three contact elements 86, 87, 88 for contacting the slip ring 85, and a lubrication device 89 with a channel 90. An outlet opening 91 of the channel 90 is located centrally above the slip ring 85, i.e., at 12:00 o'clock on the slip ring 85, in front of the first contact element 88, as viewed in a rotation direction 92 of the slip ring 85. Used oily fluid can be transported away from below the slip ring 85 in the direction of an arrow 93 due to gravity or centrifugal force. The power transmission device 84 and the lubrication device 89 form a power transmission arrangement or are encompassed by the power transmission arrangement.

[0070] For each of the descriptions of Figs. 1 to 9, in particular with regard to the components shown in a figure of Figs. 1 to 9 but not described in connection with this figure, reference is made to the other descriptions of the figures.

[0071] The objects or components shown in Figs. 1 to 9 can be combined with each other in any meaningful way.

Claims

Patent claims 1. A power transmission arrangement comprising a power transmission device (10, 26, 54, 63, 70, 84, 94) for a rotating electrical machine, in particular a synchronous machine, for transmitting an electrical excitation current into a slip ring (11, 27, 38, 76, 85, 98) which can be arranged on a shaft of a rotor of the machine, wherein the power transmission device comprises the slip ring, wherein the power transmission device comprises at least one contact element (14, 15, 30, 31, 32, 57, 58, 66, 67, 72, 73, 86, 87, 88, 95, 96), preferably designed as a brush, for contacting the slip ring, such that a sliding contact surface (16, 17) of the contact element is in contact with a circumferential contact surface (18, 43, 44, 45, 75, 97, 99) of the slip ring to form an electrically conductive sliding contact between the sliding contact surface and the peripheral contact surface, characterized in that the current transmission arrangement comprises a lubrication device (78,89, 100) for, preferably continuously, oiling the sliding contact surface and / or the peripheral contact surface with an oily fluid during operation of the machine, wherein the contact, element made of a, preferably copper-free, first carbon material, preferably - polymer-bound graphite, preferably with a graphite content of at least 80% by mass, preferably with polyphenylene sulfide (PPS) as polymer, - hard-fired graphite, preferably with a graphite content of at least 70% by mass, or - a silver-graphite mixture, preferably with a silver content of 30 mass% to 80 mass%, is formed, wherein the peripheral contact surface is made of a, preferably copper-free, second carbon material, preferably - Electrographite, preferably with a density of 1.55 g / cm 3 up to 2.1 g / cm 3, preferably with an open porosity of 5% to 20%, preferably with a flexural strength of at least 15 MPa, - polymer-bonded graphite, preferably with a density of 1.55 g / cm 3 up to 2.1 g / cm 3 , preferably with an open porosity of 5% to 15%, preferably with a flexural strength of at least 15 MPa, - Hard-fired graphite, preferably with a density of 1.55 g / cm 3 up to 3.0 g / cm 3 , preferably with an open porosity of 5% to 20%, preferably with a flexural strength of at least 15 MPa, or - a metal-graphite mixture, preferably with a density of 2.3 g / cm 3 up to 4.8 g / cm 3 , preferably with an open porosity of 5% to 15%, preferably with a flexural strength of at least 15 MPa, preferably with a metal content of at least 25% by mass.

2. Current transmission arrangement according to claim 1, characterized in that the contact element (14, 15, 30, 31, 32, 57, 58, 66, 67, 72, 73, 86, 87, 88, 95, 96) has the sliding contact surface (16, 17) on the front side.

3. Power transmission arrangement according to claim 1 or 2, characterized in that the slip ring (11, 27, 38, 76, 85, 98) has a plurality of circumferential contact surfaces (18, 43, 44, 45, 75, 97, 99).

4. Power transmission arrangement according to one of the preceding claims, characterized in that the slip ring (11, 27, 38, 76, 85, 98) comprises a carrier sleeve (39) made of an electrical insulation material, preferably polymer, and at least one contact ring (40, 41, 42) arranged on the carrier sleeve, wherein the contact ring has the circumferential contact surface (18, 43, 44, 45, 75, 97, 99).

5. Power transmission arrangement according to one of the preceding claims, characterized in that the power transmission device (10, 26, 54, 63, 70, 84, 94) comprises at least one spring element (23, 24), by means of which the sliding contact surface (16, 17) is pressed against the peripheral contact surface (18, 43, 44, 45, 75, 97, 99), preferably with a contact pressure of 7 N / cm 2 up to 35 N / cm 2 , can be pressed.

6. Power transmission arrangement according to one of the preceding claims, characterized in that the power transmission device (10, 26, 54, 63, 70, 84, 94) comprises a plurality of contact elements (14, 15, 30, 31, 32, 57, 58, 66, 67, 72, 73, 86, 87, 88, 95, 96).

7. Power transmission arrangement according to claim 6, characterized in that the plurality of contact elements (14, 15, 30, 31, 32, 57, 58, 66, 67, 72, 73, 86, 87, 88, 95, 96) are arranged such that of a plurality of circumferential contact surfaces (18, 43, 44, 45, 75, 97, 99) of the slip ring (11, 27, 38, 76, 85, 98), each circumferential contact surface can be contacted by means of at least one contact element of the plurality of contact elements.

8. Current transmission arrangement according to claim 6 or 7, characterized in that the plurality of contact elements (14, 15, 30, 31, 32, 57, 58, 66, 67, 72, 73, 86, 87, 88, 95, 96) are arranged such that the circumferential contact surface (18, 43, 44, 45, 75, 97, 99) can be contacted by means of two or at least three contact elements of the plurality of contact elements.

9. Power transmission arrangement according to claim 8, characterized in that the power transmission device (10, 26, 54, 63, 70, 84, 94) is designed such that the two or at least three contact elements (14, 15, 30, 31, 32, 57, 58, 66, 67, 72, 73, 86, 87, 88, 95, 96) of the plurality of contact elements, when the power transmission device is arranged on the machine, are distributed only along a part (12, 28) of a circumference (13, 29) of the slip ring (11, 27, 38, 76, 85, 98), wherein a center angle of a circular arc (37) defined by the part is preferably 55° to 170°.

10. Current transmission arrangement according to claim 9, characterized in that distances between each two adjacent contact elements (14, 15, 30, 31, 32, 57, 58, 66, 67, 72, 73, 86, 87, 88, 95, 96) of the at least three contact elements of the plurality of contact elements viewed in a circumferential direction (22, 33) of the slip ring (11, 27, 38, 76, 85, 98) are all the same size, partially different sizes or different sizes in pairs.

11. Current transmission arrangement according to one of the preceding claims, characterized in that the current transmission device (10, 26, 54, 63, 70, 84, 94) comprises a holding device (55, 64) in which the contact element (14, 15, 30, 31, 32, 57, 58, 66, 67, 72, 73, 86, 87, 88, 95, 96) is guided, preferably radially movable.

12. Power transmission arrangement according to claim 11, characterized in that the holding device (55) comprises a holding part (56) made of an electrically conductive material, preferably metal, in which the contact element (57, 58) is guided, wherein the contact element is electrically conductively connected to the holding part forming a busbar (61) of the power transmission device (10, 26, 54, 63, 70, 84, 94) by means of a line (59, 60), preferably a stranded wire, of the power transmission device, or that the holding device (64) is made of an electrically insulating material, preferably polymer and / or ceramic, wherein the power transmission device (10, 26, 54, 63, 70, 84, 94) comprises a busbar (65) arranged on or in the holding device, wherein the contact element (66, 67) is connected to the busbar by means of a line (68, 69), preferably stranded wire, which is electrically connected to the power transmission device.

13. Power transmission arrangement according to one of the preceding claims, characterized in that the power transmission device (10, 26, 54, 63, 70, 84, 94) comprises the lubrication device (78, 89, 100).

14. Power transmission arrangement according to one of the preceding claims, characterized in that the oiling device (78, 89, 100) has at least one channel (79, 90, 101) for the oily fluid.

15. Power transmission arrangement according to one of the preceding claims, characterized in that the contact element (14, 15, 30, 31, 32, 57, 58, 66, 67, 72, 73, 86, 87, 88, 95, 96) is produced by pressing and subsequent temperature treatment, wherein the power transmission device (10, 26, 54, 63, 70, 84, 94) is designed such that the contact element is pressed axially to a longitudinal axis of the shaft when the power transmission device (10, 26, 54, 63, 70, 84, 94) is arranged on the machine.

16. Rotating electrical machine, in particular a synchronous machine, comprising a power transmission arrangement according to one of the preceding claims.

17. Machine according to claim 16, characterized in that the machine comprises a lubrication device (78, 89, 100) of the power transmission arrangement.

18. Method for transmitting an electrical excitation current into a slip ring (11, 27, 38, 76, 85, 98) arranged on a shaft of a rotor of a rotating electrical machine, in particular a synchronous machine, wherein the slip ring is contacted by means of at least one contact element (14, 15, 30, 31, 32, 57, 58, 66, 67, 72, 73, 86, 87, 88, 95, 96) of a current transmission device (10, 26, 54, 63, 70, 84, 94), preferably designed as a brush, in such a way that a sliding contact surface (16, 17) of the contact element contacts a circumferential contact surface (18, 43, 44, 45, 75, 97, 99) of the slip ring to form an electrically conductive Sliding contact between the sliding contact surface and the peripheral contact surface, characterized in that the sliding contact surface and / or the peripheral contact surface is lubricated during operation of the machine, preferably continuously, by means of an oiling device (78, 89,100) is lubricated with an oily fluid.

19. Method according to claim 18, characterized in that the oily fluid used is engine oil and / or gear oil, preferably with a kinematic viscosity of 10 mm 2 / s up to 30 mm 2 / s at a reference temperature of 40 °C.

20. Method according to claim 18 or 19, characterized in that the oily fluid is dispensed onto the sliding contact surface and / or the peripheral contact surface (18, 43, 44, 45, 75, 97, 99) at a volume flow of 10 ml / min to 1000 ml / min.

21. Method according to one of claims 18 to 20, characterized in that that the oily fluid is discharged in an upper region of the slip ring (11, 27, 38, 76, 85, 98).

22. Method according to one of claims 18 to 21, characterized in that the oily fluid is discharged onto the sliding contact surface (16, 17) and / or the circumferential contact surface (18, 43, 44, 45, 75, 97, 99) exclusively in front of the contact element (14, 15, 30, 31, 32, 57, 58, 66, 67, 72, 73, 86, 87, 88, 95, 96) in a direction of rotation (83, 92) of the slip ring (11, 27, 38, 76, 85, 98).

23. Method according to one of claims 18 to 22, characterized in that the oily fluid is discharged through at least one outlet opening formed in the shaft and / or the slip ring and / or the contact element (14, 15, 30, 31, 32, 57, 58, 66, 67, 72, 73, 86, 87, 88, 95, 96) onto the sliding contact surface (16, 17) and / or the circumferential contact surface (18, 43, 44, 45, 75, 97, 99).

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