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

Abstract

The invention relates to a current transmission assembly (10), comprising a current transmission device (11) for a rotating machine for transmitting an electric current into or out of a rotor (13) of the machine, which rotor is formed with a slip ring (14) and / or a shaft (12) and / or a commutator, and to a method for transmitting an electric current into or out of a rotor of a rotating machine, which rotor is formed with a slip ring and / or a shaft and / or a commutator, wherein the current transmission device comprises at least one contact element (15), preferably in the form of a brush, for contacting the slip ring or the shaft or the commutator in such a way that a sliding contact surface of the contact element can contact a rotor contact surface (19) of the slip ring or the shaft or the commutator in order to form an electrically conductive sliding contact between the sliding contact surface and the rotor contact surface, wherein the current transmission device comprises at least one spring arrangement (45), by means of which the sliding contact surface can be pressed against the rotor contact surface, wherein the spring arrangement (45) is formed with at least one bimetal strip (46).

Description

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

[0002] The invention relates to a current transmission arrangement comprising a current transmission device for a rotating machine for transmitting an electric current into or from a rotor of the machine formed with a slip ring and / or a shaft and / or a commutator, and a method for transmitting an electric current into or from a rotor of a rotating machine formed with a slip ring and / or a shaft and / or a commutator, wherein the current transmission device comprises at least one contact element, preferably designed as a brush, for contacting the slip ring or the shaft or the commutator, such that a sliding contact surface of the contact element can be contacted with a rotor contact surface of the slip ring or the shaft or the commutator to form an electrically conductive sliding contact between the sliding contact surface and the rotor contact surface.wherein the current transmission device comprises at least a spring arrangement by means of which the sliding contact surface can be pressed against the rotor contact surface. The invention further relates to a rotating machine comprising a current transmission arrangement.

[0003] A current transmission arrangement or current transmission device of the type described above is well known from the prior art and is regularly used for transmitting an electric current into or from a rotor of a rotating machine, which is equipped with a slip ring and / or a shaft and / or a commutator. If the current transmission device is designed to transmit an electric current into a rotor, it can also be designed to transmit the electric current into a slip ring or commutator of the rotor. The machine can be an electric machine, in particular a synchronous machine, especially a current-excited or separately excited one, or a DC machine. If the current transmission device is designed to transmit an electric current from a rotor, it can also be designed to transmit the electric current into a slip ring or commutator of the rotor.The electrical current is conducted from a rotor shaft, preferably into a stator of the machine. This prevents unwanted current flow through the shaft's bearing points, which could lead to surface damage to the bearing bodies or bearing rings due to spot welding.

[0004] The current transmission device typically comprises at least one contact element, usually designed as a brush, for contacting the slip ring, shaft, or commutator, such that a sliding contact surface of the contact element can be contacted with a rotor contact surface of the slip ring, shaft, or commutator to form an electrically conductive sliding contact between the sliding contact surface and the rotor contact surface. The current transmission device typically includes at least one spring arrangement by means of which the sliding contact surface can be pressed against the rotor contact surface. The current transmission device can be designed as a dry-running device, i.e., operating without lubrication with an oil-like fluid, or as a wet-running device, i.e., operating with lubrication with an oil-like fluid.In a current transmission device designed as a wet rotor, the sliding contact surface and / or the rotor contact surface are lubricated with an oil-like fluid during operation of the machine.

[0005] In a current transmission device known from the prior art, particularly in a current transmission device designed as a wet rotor, the viscosity of an oily fluid changes depending on its temperature, and in particular decreases with increasing temperature. This regularly leads to so-called "lifting" of the contact element from the slip ring, shaft, or commutator, where the sliding contact surface of the contact element no longer makes contact with the rotor contact surface of the slip ring, shaft, or commutator. Such lift-off regularly results in sparking and thus damage and increased wear on the sliding contact surface of the contact element and the rotor contact surface of the slip ring, shaft, or commutator, thereby reducing the service life of the current transmission arrangement, in particular the current transmission device.the machine, in particular the slip ring or the shaft or the commutator, is adversely shortened.

[0006] The present invention is therefore based on the objective of proposing a current transmission arrangement, a rotating machine and a method for transmitting an electric current, which has or enables an increased service life.

[0007] This problem is solved by a current transmission arrangement having the features of claim 1, a rotating machine having the features of claim 15 and a method for transmitting an electric current having the features of claim 16.The current transmission arrangement according to the invention comprises a current transmission device for a rotating machine for transmitting an electric current into or from a rotor of the machine formed with a slip ring and / or a shaft and / or a commutator, wherein the current transmission device comprises at least one contact element, preferably designed as a brush, for contacting the slip ring or the shaft or the commutator, such that a sliding contact surface of the contact element can be contacted with a rotor contact surface of the slip ring or the shaft or the commutator to form an electrically conductive sliding contact between the sliding contact surface and the rotor contact surface, wherein the current transmission device comprises at least one spring arrangement by means of which the sliding contact surface can be pressed against the rotor contact surface, wherein the spring arrangement is formed with at least one bimetallic strip.

[0008] The current transmission arrangement or device according to the invention is designed to transmit an electric current into or from a rotor of a rotating machine, the rotor being equipped with a slip ring and / or a shaft and / or a commutator. If the current transmission device is designed to transmit an electric current into a rotor, it can be configured to transmit the electric current into a slip ring or commutator of the rotor. The slip ring or commutator can be arranged on the shaft. The machine can be an electric machine, in particular a synchronous machine, especially a current-excited or separately excited one, or a DC machine. The rotor contact surface can, in particular, be a circumferential contact surface of the slip ring. The commutator can, in particular, be a drum commutator, an end-face commutator, or a planar commutator.The rotor contact surface can, in particular, be a circumferential contact surface or an end contact surface of the commutator. The DC machine can, for example, be a component of a fuel pump. If the current transmission device is designed to transmit an electric current from a rotor, it can be configured to transmit or conduct the electric current from a rotor shaft, preferably into a stator of the machine. This avoids undesired current flow through bearing surfaces of the shaft, which could lead to surface damage of the bearing bodies or bearing rings due to spot welding. The current transmission arrangement then functions as a shaft grounding device. The rotor contact surface can, in particular, be a shaft contact surface of the shaft. The current transmission device comprises at least one contact element, preferably designed as a brush, for contacting the rotor or...of the slip ring or shaft or commutator, such that a sliding contact surface of the contact element can be contacted with a rotor contact surface of the rotor or of the slip ring or shaft or commutator to form an electrically conductive sliding contact between the sliding contact surface and the rotor contact surface.

[0009] According to the invention, the current transmission device comprises at least one spring arrangement by means of which the sliding contact surface can be pressed against the rotor contact surface. This ensures optimized contact and, if the current transmission device is designed as a wet rotor, the formation of a uniform film of an oil-like fluid. The spring arrangement allows the sliding contact surface to be pressed against the rotor contact surface with a contact pressure of 2 N / cm². 2 up to 35 N / cm 2The spring assembly can be pressable. It can contact the contact element, particularly with an end section of the spring assembly, and thus press the contact element against the slip ring, shaft, or commutator. The spring assembly can also be thermally coupled to the contact element. A change in the temperature of the contact element can therefore lead, at least partially, to a change in the temperature of the spring assembly. The temperature of the contact element, and, if the current transmission device is designed as a wet rotor, the temperature of the oil-like fluid contacting at least the sliding contact surface of the contact element, can change due to friction between the contact element or the sliding contact surface and the slip ring, shaft, commutator, or rotor contact surface, depending on the machine's rotational speed, specifically increasing with increasing rotational speed.

[0010] According to the invention, the spring assembly is designed with at least one bimetallic strip or bimetal. A bimetallic strip is a metal strip or band made up of two superimposed layers of different metals. The term "strip," particularly as a component of the term "bimetallic strip" or "metal strip," is to be understood broadly. Besides strip-shaped configurations in the strict sense, it also includes other geometries, such as disc-shaped or plate-shaped configurations. The two layers are connected to each other, in particular by a material bond and / or a form-fit. Due to the different coefficients of thermal expansion (CTE), in particular coefficients of linear thermal expansion, of the metals used, the metal strip or band changes its temperature when the temperature of the metal strip or band changes.The metal strip is a shape of the metal strip or band. A change in shape manifests itself as a bend. This change in shape, or bend, in turn leads to a change in the spring force of the spring assembly formed with the metal strip or band, and thus to a change in the contact pressure with which the sliding contact surface of the contact element is pressed against the rotor contact surface of the slip ring, shaft, or commutator by means of the spring assembly. The idea underlying the invention is therefore not so much aimed at the deformation of the spring assembly or the bimetallic strip, but rather at the resulting change in the spring force. The design of the spring assembly with the bimetallic strip thus enables an adjustment of the contact pressure that depends on the temperature of the spring assembly, in particular the bimetallic strip, or the temperature of the contact element or the temperature of the oily fluid.In particular, when the power transmission device is designed as a wet rotor, lifting of the contact element from the slip ring, shaft, or commutator, where the sliding contact surface of the contact element no longer makes contact with the rotor contact surface of the slip ring, shaft, or commutator, and where this lifting is caused by the viscosity of an oily fluid, which changes depending on the temperature of the oily fluid, and in particular decreases with increasing temperature, can be avoided by adjusting the contact pressure in a temperature-dependent manner. Therefore, sparking and thus damage and wear on the sliding contact surface of the contact element and the rotor contact surface of the slip ring, shaft, or commutator can be avoided or reduced, thereby extending the service life of the power transmission arrangement, in particular the power transmission device.The contact area of ​​the machine, in particular the slip ring, shaft, or commutator, can be advantageously increased. Furthermore, mechanical power losses resulting from friction between the contact element or the sliding contact surface and the slip ring, shaft, commutator, or rotor contact surface can be reduced.

[0011] Advantageously, the bimetallic strip can be a metal strip or band. The bimetallic strip can consist of a first layer of a metal with a first coefficient of linear expansion and a second layer of a second metal with a second coefficient of linear expansion arranged on top of the first layer. Here, "metal" can refer to either a pure metal or a metal alloy. Therefore, the first metal and / or the second metal can be a pure metal or a metal alloy.

[0012] Advantageously, the bimetallic strip can be formed with a first metal and a second metal different from the first metal, wherein the first metal and the second metal can be selected from a group comprising: aluminum, aluminum alloy, in particular AlCuMgl, AlMgSil, AlMg5, AlCuNi, bronze, in particular CuSnö, chromium, chromium-nickel, in particular CrNi 80 20, iron, cast iron or gray cast iron, indium, cobalt, constantan, in particular CuNi44, copper, copper beryllium, in particular CuBe2, magnesium, magnesium alloy, magnetic steel, in particular AlNi, manganese, brass, in particular CuZn37, molybdenum, Monel or Monel metal, nickel silver, in particular CuNi2Zn24, nickel, nickel beryllium, in particular NiBe2, niobium, red brass, silver, sintered iron, steel, in particular stainless steel or chromium steel.Chromium-nickel steel, in particular 13Cr, 18Cr, 41Cr4, X10Cr3, X12CrNil88, manganese steel, in particular 14Mn, MnNilOCul8, MnNilöCulO, Ni steel, in particular 8Ni, 20Ni, 30Ni, 36Ni or Invar, 47Ni, NiMn 20 6, tungsten steel, in particular.

[0013] 18W, unalloyed or low-alloy steel, in particular C15, C35, C60, tantalum, titanium, tombac, in particular CuZn5, vanadium, bismuth, tungsten, zinc, zinc alloy, tin, and zirconium. All combinations of any two metals selected from the group, in particular pure metals and metal alloys, for forming the bimetallic strip are hereby considered disclosed. The metals listed in the group differ in particular with respect to their coefficients of linear expansion. The first metal and / or the second metal may be a metal alloy of the metals listed in the group. In a preferred embodiment, the bimetallic strip may be formed with, preferably stainless, steel as the first metal and zinc as the second metal. Metals other than those listed in the group are conceivable for forming the bimetallic strip.Advantageously, the spring assembly can include a spring element, wherein the spring element is formed at least partially or section by section, in particular at least at its end or on at least one end section of the spring element, from the bimetallic strip, or the spring element, formed separately from the bimetallic strip and preferably of a conventional type or not formed from a bimetallic strip, can be mechanically coupled to or engage with the bimetallic strip. If the spring element is formed at least partially from the bimetallic strip, at least one end section of the spring element that contacts or engages with the contact element and / or, if present, at least one end section of the spring element that does not contact or engage with the contact element can be formed from the bimetallic strip. Otherwise, the spring element can be of a conventional type or...The spring element may not be formed from a bimetallic strip. The spring element may be formed entirely from the bimetallic strip or along its entire length. The spring element may then form the spring assembly. If the spring element, preferably conventional or not formed from a bimetallic strip, is formed separately from the bimetallic strip, the spring assembly may include both the spring element and the bimetallic strip, or the spring assembly may be formed by both the spring element and the bimetallic strip. The bimetallic strip, which is mechanically coupled to or engaged with the spring element, may exert a force on the spring element that varies depending on the temperature of the spring assembly, particularly the temperature of the bimetallic strip.Depending on the temperature and arrangement of the bimetallic strip, the force can be essentially in the same direction as the spring force of the spring element or in the opposite direction. In all cases, the bimetallic strip changes the spring force when the temperature of the spring assembly, and especially of the bimetallic strip, changes. Advantageously, the spring element can be designed as a coil spring, a rolling band spring (in particular a simple or double rolling band spring), a helical compression spring, or a torsion spring. A coil spring or rolling band spring exhibits low force loss over a distance. If the spring element is designed as a coil spring or rolling band spring, it can be formed from a helical bimetallic strip or a rolled bimetallic band.The torsion spring can engage with the contact element via a first leg section and with the bimetallic strip (which is separate from the torsion spring) via a second leg section, thus being mechanically coupled to the bimetallic strip. The bimetallic strip can engage with an end of the helical compression spring facing the contact element, i.e., positioned between the helical compression spring and the contact element, or with an end of the helical compression spring facing away from the contact element.

[0014] The spring element or bimetallic strip can be formed from a sheet of metal. The spring force, or the range of spring force variation, can then be easily adjusted by changing the sheet width and / or thickness.

[0015] The spring assembly or spring element can contact the contact element, in particular with an end section of the spring assembly or spring element, or engage with the contact element with the end section.

[0016] The spring element can be arranged on a rigid or rotatable mounting point on the power transmission device. In particular, the spring element, which may be designed as a coil spring, roller spring, or torsion spring, can be arranged on a rotatable mounting point on the power transmission device, especially via a thread, particularly a screw element. The bimetallic strip, which is separate from the spring element and mechanically coupled to it, can act on the mounting point, the screw element, or the spring element itself, depending on the temperature, particularly that of the bimetallic strip, causing the spring element to rotate, thereby changing the spring force of the spring element. The mounting point can be rotatable by at least 90°, preferably at least 180°.

[0017] Advantageously, the spring arrangement, in particular the bimetallic strip, can be arranged and / or designed on the current transmission device such that an increase in temperature, in particular of the spring arrangement, in particular of the bimetallic strip, and / or of the contact element and / or of an oily fluid, can reduce the contact pressure, and an increase in the contact pressure can be achieved when the temperature decreases, or vice versa. When reducing the contact pressure, it can also be reduced to essentially zero. In particular, the bimetallic strip, which is designed separately from the spring element, can press against the spring element in such a way that the spring element is effectively deactivated in its spring action on the contact element. The spring arrangement, in particular the spring element, or...The bimetallic strip, particularly at its end section, can bend away from the contact element or the spring element to reduce the contact pressure when the temperature of the contact element or, where applicable, the temperature of the oily fluid or the spring assembly (especially the bimetallic strip, which is thermally coupled to the contact element) increases. Conversely, when the temperature of the contact element or, where applicable, the temperature of the oily fluid or the spring assembly (especially the bimetallic strip, which is thermally coupled to the contact element) decreases, the bimetallic strip can bend towards the contact element or spring element to increase the contact pressure. The increase or decrease in the temperature of the contact element or, where applicable, the temperature of the oily fluid or the spring assembly (especially the bimetallic strip, which is thermally coupled to the contact element) can cause this bending.The temperature of the spring assembly, particularly the bimetallic strip, can result from an increase or decrease in frictional heat caused by an increase or decrease in the machine's rotational speed. This frictional heat arises from friction between the contact element or the sliding contact surface and the slip ring, shaft, commutator, or rotor contact surface, or from general machine heat loss. Thus, the spring force with which the spring assembly or spring element presses on the contact element, and consequently the contact pressure, can be increased at a comparatively low temperature or during cold running, and decreased at a comparatively high temperature.Alternatively, conversely, the spring arrangement can be arranged and / or designed on the current transmission device in such a way that, in the event of an increase in temperature, in particular of the spring arrangement, in particular of the bimetallic strip, and / or of the contact element and / or of an oil-like fluid, a contact pressure can be increased and, in the event of a decrease in temperature, the contact pressure can be decreased.

[0018] The sliding contact surface and / or the rotor contact surface and / or the spring arrangement, in particular the bimetallic strip, can be wetted, in particular oiled, with a fluid, in particular an oily fluid, during operation of the machine.

[0019] Advantageously, the current transmission arrangement can include an oiling device for the, preferably continuous, lubrication of the sliding contact surface and / or the rotor contact surface and / or the spring assembly, in particular the bimetallic strip, with an oil-like fluid during machine operation. The oiling device can be part of the current transmission device or the machine. The oiling device can be designed separately from the current transmission device. In particular, the current transmission device can be an external oiling device designed separately from the current transmission device and / or the machine. Accordingly, the current transmission arrangement or current transmission device can be designed as a wet rotor.The application of the oil-like fluid to the sliding contact surface and / or the rotor contact surface provides lubrication, thus reducing friction between the two surfaces. This, in turn, reduces wear on both surfaces, thereby advantageously extending the service life of the power transmission assembly, device, machine, slip ring, shaft, or commutator. Furthermore, the application of the oil-like fluid to the sliding contact surface and / or the rotor contact surface advantageously dissipates heat, particularly that generated by friction between the two surfaces. This eliminates the need for a ventilation system, saving space and advantageously increasing the efficiency of the machine or gearbox into which it may be integrated.Alternatively, the power transmission arrangement or power transmission device can be designed as a dry-running unit.

[0020] Advantageously, the power transmission device can include the lubrication device. Accordingly, the lubrication device can be part of the power transmission device or integrally formed with it. Alternatively, the lubrication device can be included by the machine or be an external lubrication device separate from the power transmission device or machine.

[0021] 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 of the channel, particularly at its end. The channel can be arranged in a holding device of the current transmission device, in which the contact element can be guided, preferably radially or axially. Alternatively, the channel can also be formed by the holding device or the contact element. Preferably, in the case of multiple rotor contact surfaces, the channel has only one outlet opening per rotor contact surface. The channel can form a branch, particularly a fork, to distribute the oily fluid to the individual rotor contact surfaces in the case of multiple rotor contact surfaces. It is also conceivable that, in the case of multiple contact elements, the channel has one outlet opening per contact element.Other methods of lubrication, especially without a channel, are conceivable.

[0022] If the machine is a DC machine for a fuel pump, which is completely immersed in the medium during operation of the machine or fuel pump, the bimetallic strip can also be surrounded by the fuel or fluid.

[0023] Advantageously, engine oil and / or transmission oil can be used as the oil-like fluid, which is regularly present in a motor or transmission in which the power transmission arrangement or power transmission device may be integrated.

[0024] The rotor can comprise at least one slip ring arranged on the shaft, or a plurality of slip rings arranged on the shaft. Each slip ring can then have a rotor contact surface.

[0025] The contact element can be made of a first carbon material, preferably copper-free, or based on graphite.

[0026] The rotor contact surface, slip ring, shaft, or commutator in a region of the rotor contact surface can be made of a second carbon material, preferably copper-free, or based on graphite or a metal or metallic material. Advantageously, the contact element, preferably rod-shaped, can have the sliding contact surface on its end face. The spring assembly, spring element, or bimetallic strip can then contact the contact element from the rear.

[0027] The longitudinal axis of the contact element can extend transversely to a longitudinal axis or axis of rotation of the shaft, or to an axis of rotation of the slip ring or commutator. The longitudinal axis of the contact element, or an extension of the longitudinal axis of the contact element in the direction of the slip ring, shaft, or commutator, can pass through the axis of rotation of the slip ring or commutator, or the longitudinal axis or axis of rotation of the shaft.

[0028] The contact element can, for example, have a circular, square or rectangular cross-section.

[0029] Advantageously, the slip ring, shaft, or commutator can have a plurality of rotor contact surfaces, preferably at least two, and in particular two or three. The rotor contact surfaces can be spaced apart from each other, preferably equidistantly, and parallel to each other, in the direction of the axis of rotation of the slip ring, shaft, or commutator. Each rotor contact surface can then be assigned to a phase.

[0030] Advantageously, the current transmission device can comprise a plurality of contact elements. The current transmission device can also comprise a plurality of spring assemblies corresponding to the plurality of contact elements, so that each contact element can be assigned one of the spring assemblies. At least one of the spring assemblies can be configured with at least one bimetallic strip. At least two or even all of the spring assemblies can be configured with at least one bimetallic strip each. However, it is not necessary for every spring assemblies to be configured with a bimetallic strip. For example, several, in particular three, contact elements and several, in particular three, spring assemblies assigned to each pole can be provided, with a bimetallic strip being provided in only one of the spring assemblies per pole.

[0031] Advantageously, the plurality of contact elements can be arranged such that each rotor contact surface of the slip ring, shaft, or commutator can be contacted by means of at least one contact element of the plurality of contact elements or a respective slip contact surface. In other words, a number of contact elements can correspond to at least a number of rotor contact surfaces. In one embodiment of the current transmission arrangement or current transmission device, the current transmission device can comprise at least one first contact element for contacting a first rotor contact surface of the slip ring, shaft, or commutator and at least one second contact element for contacting a second rotor contact surface of the slip ring, shaft, or commutator.The majority of rotor contact surfaces can, in principle, also be provided by a majority of slip rings arranged on the shaft.

[0032] Advantageously, the plurality of contact elements can be configured such that the rotor contact surface, or each rotor contact surface, can be contacted by means of at least two, two, or at least three contact elements of the plurality of contact elements, or of a respective slip ring contact surface. Therefore, at least two contact elements, in particular two or three contact elements, can be provided for the rotor contact surface, or for each rotor 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 rotor contact surface of the slip ring, shaft, or commutator, and at least two second contact elements for contacting a second rotor contact surface of the slip ring, shaft, or commutator.Providing multiple contact elements that contact a rotor contact surface enables the transmission of a higher current. Furthermore, in the case of a current transmission arrangement or device designed as a wet rotor, hydrodynamic effects can be avoided and uniform lubrication achieved.

[0033] Advantageously, the current transmission device can be designed such that the two or at least three contact elements of the plurality of contact elements, when the current transmission arrangement or device is mounted on the machine, can be distributed only along a portion of the circumference of the slip ring, shaft, commutator, or rotor contact surface. This can advantageously prevent dry running. Furthermore, this allows the current transmission arrangement or device to be advantageously mounted laterally on the machine or shaft, eliminating the need for a complex installation over the shaft or rotor.

[0034] 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.

[0035] Depending on the embodiment of the current transmission arrangement or device, the distances between any 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, shaft, or commutator, can all be the same, partially different, or different in pairs. Advantageously, the current transmission device can include a holding device in which the contact element can be guided, preferably radially or axially movably in a radial direction of the slip ring, shaft, or commutator.

[0036] In one embodiment of the current transmission arrangement or device, the holding element can comprise at least one retaining part made of an electrically conductive material, preferably metal, in which the contact element can be guided. The contact element can be electrically connected to the retaining part, in particular by means of a connecting element or a conductor, preferably a stranded wire, of the current transmission device. Thus, the retaining part can simultaneously function as a busbar. The retaining part can be manufactured by stamping. Preferably, the retaining part can be designed as a stamped metal part. The conductor 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 retaining part at the other end. The spring arrangement or...The spring element can be arranged on the retaining part, in particular on a projection of the retaining part. Furthermore, the retaining part can have a connection section with a terminal via which the retaining part can be connected to an electrical conductor for supplying electric current or to a pole of a voltage source.

[0037] The holding device can comprise at least one support part made of an electrical insulating material, in particular a polymer, wherein the holding part can be arranged on the support part. In one embodiment of the current transmission arrangement or current transmission device, the current transmission device can comprise a first holding part in which at least one first contact element, in particular three first contact elements, of the current transmission device can be guided, and a second holding part in which at least one second contact element, in particular three second contact elements, of the current transmission device can be guided, wherein the first holding part can be arranged on a first side of the support part and the second holding part can be arranged on a second side of the support part. The first side can be opposite the second side.The first contact element can be designed to contact a first rotor contact surface, and the second contact element can be designed to contact a second rotor contact surface. This allows the contact elements, which contact different rotor contact surfaces or are assigned to different phases, to be electrically isolated from one another. The carrier part can have a receptacle, in particular a through-hole or a recess, for receiving the shaft. Furthermore, the carrier part can form a channel for the oil-like fluid, particularly within its interior.

[0038] The rotating machine according to the invention comprises a current transmission arrangement according to the invention.

[0039] The machine can be an electric machine, in particular a synchronous machine, especially one that is electrically excited or separately excited. A current transmission device of the current transmission arrangement can be provided for transmitting an electric current or excitation current to a slip ring of the rotor arranged on a shaft of the machine's rotor, wherein the rotor can include an excitation winding electrically connected to the slip ring for generating a magnetic excitation field. The machine can also be a DC machine. A fuel pump can be included in the DC machine. Furthermore, the machine can be a gearbox.

[0040] The machine may include a lubrication system for the power transmission device. Accordingly, the lubrication system may be a component of the machine or integrally formed with it. For example, the lubrication system may be designed such that lubrication occurs via the shaft.

[0041] In the inventive method for transmitting an electric current into or from a rotor of a rotating machine, the rotor being formed with a slip ring and / or a shaft and / or a commutator, the slip ring or the shaft or the commutator is contacted by means of at least one contact element, preferably designed as a brush, of a current transmission device of a current transmission arrangement, such that a sliding contact surface of the contact element is contacted with a rotor contact surface of the slip ring or the shaft or the commutator to form an electrically conductive sliding contact between the sliding contact surface and the rotor contact surface, wherein the sliding contact surface is pressed against the rotor contact surface by means of at least one spring arrangement of the current transmission device, wherein the spring arrangement is formed with at least one bimetallic strip.

[0042] For the advantageous effects of the method according to the invention, reference is made to the description of advantages of the current transmission arrangement according to the invention.

[0043] Further advantageous embodiments of the method according to the invention result from the feature descriptions of the dependent claims relating to device claim 1.

[0044] A preferred embodiment of the invention is explained in more detail below with reference to the accompanying drawings.

[0045] They show:

[0046] Fig. 1 shows a front view of a power transmission device arranged on a shaft;

[0047] Fig. 2 a front view of the power transmission device; Fig. 3 a rear view of the power transmission device;

[0048] Fig. 4 shows a sectional view of the power transmission device;

[0049] Fig. 5 shows another sectional view of the power transmission device;

[0050] Fig. 6 shows an underside view of the power transmission device;

[0051] Fig. 7 shows an exploded view of the power transmission device;

[0052] Fig. 8 shows a schematic representation of a spring arrangement in a first embodiment;

[0053] Fig. 9 shows a schematic representation of a spring arrangement in a second embodiment;

[0054] Fig. 10 shows a schematic representation of a spring arrangement in a third embodiment;

[0055] Fig. 11a shows a schematic representation of a spring arrangement in a fourth embodiment;

[0056] Fig. 11b shows a schematic representation of a spring arrangement in a fifth embodiment;

[0057] Fig. 12 shows a schematic representation of a spring arrangement in a sixth embodiment;

[0058] Fig. 13 shows a schematic representation of a spring arrangement in a seventh embodiment;

[0059] Fig. 14 shows a schematic representation of a spring arrangement in an eighth embodiment;

[0060] Fig. 15 shows a schematic representation of a rotatable mounting point for the spring assembly shown in Fig. 14; Fig. 16 shows a schematic representation of a spring assembly in a ninth embodiment;

[0061] Fig. 17 shows a schematic representation of a spring arrangement in a tenth embodiment;

[0062] Fig. 18 shows a schematic representation of a spring arrangement in an eleventh embodiment.

[0063] A combined view of Figures 1 to 7 shows a current transmission arrangement 10, comprising a current transmission device 11 for a rotating, preferably electric, machine, in particular a synchronous machine, not shown here, for transmitting an electric current or excitation current to a slip ring 14 of the rotor 13 arranged on a shaft 12 of a rotor 13 of the machine, which is shown here only in sections.

[0064] The power transmission device 11 comprises three first contact elements 15 and three second contact elements 16 for contacting the slip ring 14, such that a respective first sliding contact surface 17 of the first contact elements 15 and a respective second sliding contact surface 18 of the second contact elements 16 can be contacted with a first rotor contact surface 19 of the slip ring 14 and a second rotor contact surface 18 of the slip ring 14 (not shown) to form an electrically conductive sliding contact between the respective first sliding contact surface 17 and the first rotor contact surface 19 and between the respective second sliding contact surface 18 and the second rotor contact surface 18. The first rotor contact surface 19 and the second rotor contact surface are each configured as a circumferential contact surface of the slip ring 14. The first contact elements 15 are configured identically to the second contact elements 16.The current transmission device 11 is designed such that the first contact elements 15 or second contact elements 16 are arranged distributed only along a part of a circumference of the slip ring 14, wherein a central angle of a circular arc defined by the part (not shown here) is 55° to 170°.

[0065] The current transmission device 11 further comprises, for each first contact element 15 and second contact element 16, a spring element 20 forming a spring arrangement 45 of the current transmission device 11, by means of which the respective first sliding contact surface 17 can be pressed against the first rotor contact surface 19 and the respective second sliding contact surface 18 against the second rotor contact surface. The spring elements 20, each designed as a spiral spring, are each formed entirely from a bimetallic strip 46.

[0066] The current transmission device 11 further comprises a holding device 21 in which the first contact elements 15 and the second contact elements 16 are guided radially movably. The holding device 21 comprises a first holding part 22 made of an electrically conductive material, in which the first contact elements 15 are guided, and a second holding part 23 made of an electrically conductive material, in which the second contact elements 16 are guided, wherein the first contact elements 15 are electrically connected to the first holding part 22 and the second contact elements 16 are each electrically connected to the second holding part 23 by means of a conductor 24 of the current transmission device 11.

[0067] The first retaining part 22 and the second retaining part 23 form first receiving sections 25 and second receiving sections 26, respectively, which receive and guide the first contact elements 15 and second contact elements 16, respectively. The spring assemblies 45 and spring elements 20 are arranged on the first retaining part 22 and the second retaining part 23, respectively. The first retaining part 22 and the second retaining part 23 form first projections 27 and second projections 28, respectively, on which the spring assemblies 45 and spring elements 20 are arranged. The first projections 27 and second projections 28 serve as rigid mounting points. Furthermore, the first retaining part 22 and the second retaining part 23 form a first connection section 29 with a first connection 30 and a second connection section 31 with a second connection 32, respectively. The first terminal 30 or second terminal 32 is used to connect the power transmission arrangement 10 or power transmission device 11 to a negative terminal or

[0068] Positive terminal of a voltage source (not shown here). By applying a voltage to the current transmission arrangement 10 or current transmission device 11, the electrical excitation current can be supplied. Each spring arrangement 45 or spring element 20 contacts a first contact element 15 or second contact element 16 associated with the respective spring arrangement 45 or spring element 20 with a respective end section 33 of the spring arrangement 45 or spring element 20 on one of the first rear surfaces 34 of the first sliding contact surface 17 or second sliding contact surface 18 opposite the end face of the second rear surface 35 of the first contact element 16. The spring arrangements 45 or spring elements 20 are designed and arranged on the current transmission device 11 such that the spring arrangements 45 or spring elements 20 areSpring elements 20, at least with their end sections 33, deform or bend when the temperature of the first contact elements 15 or second contact elements 16 increases, or when the temperature of an oily fluid increases, or when the temperature of the spring assemblies 45 or spring elements 20 thermally coupled to the first contact elements 15 or second contact elements 16 increases, thus reducing the contact pressure. Conversely, when the temperature of the first contact elements 15 or second contact elements 16 decreases, or when the temperature of the oily fluid decreases, or when the temperature of the spring assemblies 45 or spring elements 20 increases, the spring elements 20 deform or bend, at least with their end sections 33. This deformation or bending results in a change in the spring force of the spring assemblies 45 or spring elements 20.

[0069] Spring elements 20, as a result of which the contact pressure is changed. The holding device 21 further comprises a support part 36 made of an electrical insulating material, wherein the first holding part 22 is arranged on a first side 37 of the support part 36 and the second holding part 23 is arranged on a second side 38 of the support part 36 opposite the first side 37.

[0070] The power transmission arrangement 11 further comprises an oiling device 39 for oiling the first sliding contact surfaces 17 or second sliding contact surfaces 18 or the first rotor contact surface 19 or the second rotor contact surface with the oily fluid. The power transmission device 11 includes the oiling device 39. The support part 36 forms a channel 40 for the oily fluid within its interior. The channel 40 has a first connection 41 or a second connection 42 at one end, through which the oily fluid can be selectively supplied. Furthermore, the channel 40 has at its other end a first outlet opening 43 or a second outlet opening 44, through which the oil-like fluid flows from the channel 40 adjacent to the middle first contact element 15 or second contact element 16 onto at least the first sliding contact surface 17 of the middle first contact element 15 or the first rotor contact surface 19 or .the second sliding contact surface 18 of the middle second contact element 16 or the second rotor contact surface can exit.

[0071] Figures 8 to 18 schematically show different embodiments of spring assemblies. For the sake of simplicity, the same reference numerals are used in the following for objects of identical construction or function.

[0072] Fig. 8 shows a spring assembly 47, which is formed by a spring element 48 designed as a coil spring. The spring element 48 is formed entirely from a bimetallic strip 49, which consists of a first layer 50 of a first metal and a second layer 51 of a second metal arranged on the first layer 50. The spring assembly 45 is designed like the spring assembly 47.

[0073] Fig. 9 shows a spring arrangement 47, which is formed by a spring element 48 designed as a simple roller band spring. The spring element 48 is formed entirely from a bimetallic strip 49, which consists of a first layer 50 of a first metal and a second layer 51 of a second metal arranged on the first layer 50.

[0074] Fig. 10 shows a spring arrangement 47, which is formed by a spring element 48 designed as a double roller band spring. The spring element 48 is formed entirely from a bimetallic strip 49, which consists of a first layer 50 of a first metal and a second layer 51 of a second metal arranged on the first layer 50.

[0075] Fig. 11a shows a spring assembly 47, which consists of a spring element 48 designed as a conventional helical compression spring and a bimetallic strip 49 formed separately from the spring element 48. The bimetallic strip 49, arranged at the end of the spring element 48 between the spring element 48 and a contact element 52, is formed from a first layer 50 of a first metal and a second layer 51 of a second metal arranged on the first layer 50. Instead of engaging with an end of the spring element 48 facing the contact element 52, as shown in Fig. 11a, the bimetallic strip 49 can also engage with an end of the spring element 48 facing away from the contact element 52, as in a spring assembly 47 shown in Fig. 11b, which otherwise corresponds to the spring assembly 47 shown in Fig. 11a.

[0076] Fig. 12 shows a spring assembly 47, which is formed by a spring element 48 designed as a conventional coil spring and a bimetallic strip 49 formed separately from the spring element 48. The bimetallic strip 49, which is arranged at the end of the spring element 48, is formed from a first layer 50 of a first metal and a second layer 51 of a second metal arranged on the first layer 50.

[0077] Fig. 13 shows a spring assembly 47, which is formed by a spring element 48 designed as a torsion spring. The spring element 48 is formed at each end, or in a region of two leg sections 53, 54 of the spring element 48 or the torsion spring, from a bimetallic strip 49, and otherwise in a conventional manner. The spring assembly 47 is therefore formed with two bimetallic strips 49. The bimetallic strips 49 each consist of a first layer 50 of a first metal and a second layer 51 of a second metal arranged on the first layer 50. The spring element 48 can also be formed from a bimetallic strip 49 only in the region of a first leg section 53 or second leg section 54.The spring element 48 can then be fixed to one end of the first leg section 53 or second leg section 54, wherein the spring element 48 can engage with a second leg section 54 or first leg section 53 not formed from a bimetallic strip 49 and with a contact element not shown here.

[0078] A combined view of Figures 14 and 15 shows a spring assembly 47, which consists of a spring element 48 designed as a conventional coil spring and a bimetallic strip 49 designed separately from the spring element 48. The spring element 48 is arranged via a screw element 57 or a thread 56 of the screw element 57 at a mounting point 55 rotatable by 180°. The bimetallic strip 49 engages with the mounting point 55 or with an upper or lower end of the screw element 57 or the thread 56 in such a way that a temperature-dependent bending of the bimetallic strip 49 causes the mounting point 55, and thus the spring element 48 arranged on the mounting point 55, to rotate, thereby achieving a temperature-dependent change in the spring force of the spring element 48. The spring element 48 is arranged on the mounting point 55 by means of a spiral section 58 of the spring element 48 or the spiral spring.The spring element 48 engages with a contact element not shown here at an end section 59 of the spring element 48 or the spiral spring.

[0079] Fig. 16 shows a spring assembly 47, which consists of a spring element 48 designed as a conventional coil spring and a bimetallic strip 49 designed separately from the spring element 48. Depending on the temperature of the bimetallic strip 49, the bimetallic strip presses against the spring element 48 or a coil section 58 of the spring element 48 or the coil spring. The spring element 48 engages with a contact element (not shown) at an end section 59 of the spring element 48 or the coil spring.

[0080] Fig. 17 shows a spring assembly 47, which consists of a spring element 48 designed as a conventional torsion spring and a bimetallic strip 49 designed separately from the spring element 48. The spring element 48 is loosely mounted on a rigid mounting point 55. The bimetallic strip 49 engages with a first leg section 53 of the spring element 48, i.e., the torsion spring, while a second leg section 54 of the spring element 48 engages with a contact element (not shown). The leg sections 53 and 54 form an angle of 180°.

[0081] Fig. 18 shows a spring assembly 47, which consists of a spring element 48 designed as a conventional torsion spring and a bimetallic strip 49 designed separately from the spring element 48. The bimetallic strip 49 engages with a first leg section 53 of the spring element 48, i.e., the torsion spring, while a second leg section 54 of the spring element 48 engages with a contact element not shown. The leg sections 53 and 54 form an angle of 90°.

[0082] The embodiments and features shown in or described in Figures 1 to 13 can be combined with one another in any meaningful way. In particular, the current transmission arrangement 10 or current transmission device 11 shown in Figures 1 to 7 can include one of the spring arrangements 47 shown in Figures 8 to 18.

Claims

Patent claims 1. Current transmission arrangement (10) comprising a current transmission device (11) for a rotating machine for transmitting an electric current into or from a rotor (13) of the machine, the rotor being formed with a slip ring (14) and / or a shaft (12) and / or a commutator, wherein the current transmission device comprises at least one contact element (15, 16, 52), preferably formed as a brush, for contacting the slip ring or the shaft or the commutator, such that a sliding contact surface (17, 18) of the contact element can be contacted with a rotor contact surface (19) of the slip ring or the shaft or the commutator to form an electrically conductive sliding contact between the sliding contact surface and the rotor contact surface, wherein the current transmission device comprises at least one spring arrangement (45, 47) by means of which the sliding contact surface can be pressed against the rotor contact surface. characterized by , that the spring arrangement is designed with at least one bimetallic strip (46, 49).

2. Power transmission arrangement according to claim 1 , characterized by , that the bimetallic strip (46, 49) is formed with a first metal and a second metal different from the first metal, wherein the first metal and the second metal are chosen from a group comprising: aluminum, aluminum alloy, bronze, chromium, chromium nickel, iron, cast iron, indium, cobalt, constantan, copper, copper beryllium, magnesium, magnesium alloy, magnet steel, manganese, brass, molybdenum, Monel, nickel silver, nickel, nickel beryllium, niobium, red brass, silver, sintered iron, steel, tantalum, titanium, tombac, vanadium, bismuth, tungsten, zinc, zinc alloy, tin and zirconium.

3. Power transmission arrangement according to claim 1 or 2, characterized by , that the spring arrangement (45, 47) has a spring element (20, 48), wherein the spring element is formed at least partially, in particular at least at the end, from the bimetallic strip (46, 49) or the spring element formed separately from the bimetallic strip is mechanically coupled to the bimetallic strip.

4. Power transmission arrangement according to claim 3 , characterized by , that the spring element (20, 48) is designed as a spiral spring, roller band spring, helical compression spring or torsion spring.

5. Power transmission arrangement according to claim 3 or 4, characterized by , that the spring element (20, 48) is arranged on a rigid or rotatable mounting point (55) on the power transmission device (1 1 ).

6. Power transmission arrangement according to one of the preceding claims, characterized by , that the spring arrangement (45, 47) is arranged and / or designed on the current transmission device ( 1 1 ) such that, in the event of an increase in temperature, in particular of the spring arrangement and / or the contact element and / or an oily fluid, the contact pressure can be reduced and, in the event of a decrease in temperature, the contact pressure can be increased or vice versa.

7. Power transmission arrangement according to one of the preceding claims, characterized by , that the current transmission arrangement ( 10) comprises an oiling device (39) for the, preferably continuous, oiling of the sliding contact surface ( 17, 18) and / or the rotor contact surface ( 19) and / or the spring arrangement (45 , 47), in particular the bimetallic strip (46, 49), with an oil-like fluid during operation of the machine.

8. Power transmission arrangement according to one of the preceding claims, characterized by , that the current transmission device ( 1 1 ) comprises a plurality of contact elements ( 15, 16, 52), wherein the current transmission device comprises a plurality of spring arrangements (45, 47) corresponding to the plurality of contact elements, such that each contact element is associated with one of the spring arrangements, wherein at least one of the spring arrangements is formed with at least one bimetallic strip (46, 49).

9. Power transmission arrangement according to claim 8, characterized by , that the plurality of contact elements ( 15, 16, 52) is arranged such that each rotor contact surface can be contacted by means of at least one contact element of the plurality of contact elements from a plurality of rotor contact surfaces ( 19) of the slip ring ( 14) or the shaft ( 12) or the commutator.

10. Power transmission arrangement according to claim 8 or 9, characterized by , that the majority of contact elements ( 15, 16, 52) are arranged such that the rotor contact surface ( 19) can be contacted by means of two or at least three contact elements of the majority of contact elements.

1. Power transmission arrangement according to claim 10, characterized by , that the current transmission device ( 1 1 ) is designed such that the two or at least three contact elements ( 15, 16, 52) of the plurality of contact elements, when the current transmission device is considered on the machine, are distributed only along a part of a circumference of the slip ring ( 14) or the shaft ( 12) or the commutator, wherein a central angle of a circular arc defined by the part is preferably 55° to 170°.

12. Power transmission arrangement according to one of the preceding claims, characterized by , that the current transmission device ( 1 1 ) comprises a holding device (21 ) in which the contact element ( 15, 16, 52) is guided, preferably radially or axially movable.

13. Power transmission arrangement according to claim 12, characterized by , that the holding device (21) comprises at least one holding part (22, 23) made of an electrically conductive material, preferably metal, in which the contact element (15, 16, 52) is guided, wherein the contact element is electrically connected to the holding part, in particular by means of a line (24), preferably stranded wire, of the current transmission device (11).

14. Power transmission arrangement according to claim 13, characterized by , that the holding device (21) comprises a support part (36) formed from an electrical insulating material, in particular polymer, wherein the holding part (22, 23) is arranged on the support part.

15. Rotating machine comprising a power transmission arrangement (10) according to any one of the preceding claims.

16. Method for transmitting an electric current into or from a rotor (13) of a rotating machine, the rotor being formed with a slip ring (14) and / or a shaft (12) and / or a commutator, wherein the slip ring or the shaft or the commutator is contacted by means of at least one contact element (15, 16, 52) of a current transmission device (11) of a current transmission arrangement (10), preferably designed as a brush, such that a sliding contact surface (17, 18) of the contact element is contacted with a rotor contact surface (19) of the slip ring or the shaft or the commutator to form an electrically conductive sliding contact between the sliding contact surface and the rotor contact surface, wherein the sliding contact surface is pressed against the rotor contact surface by means of at least one spring arrangement (45, 47) of the current transmission device. characterized by , that the spring arrangement is designed with at least one bimetallic strip (46, 49).

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