ELECTRIC MACHINE

Description

[0001] The present invention relates to an electrical machine, in particular for an electrically operated drive train of a motor vehicle, comprising a rotor which is rotatably mounted relative to a stator, wherein the rotor has a rotor shaft with at least one first rotor body which is arranged on the rotor shaft in a rotationally and displacement-proof manner, wherein the stator comprises a first stator body and a second stator body which are spaced apart from one another and the first stator body has a first stator winding and the second stator body has a second stator winding, wherein the first stator winding is arranged within a first hydraulic chamber and the second stator winding is arranged within a second hydraulic chamber, within which the respective stator windings can each be contacted by a hydraulic fluid, at least in sections.

[0002] Electric motors are increasingly being used to power motor vehicles, creating alternatives to combustion engines that require fossil fuels. Considerable efforts have already been made to improve the everyday suitability of electric drives and also to provide users with the same level of driving comfort they are accustomed to.

[0003] A detailed description of an electric drive can be found in an article in the magazine ATZ, Volume 113, May 2011, pages 360-365, by Erik Schneider, Frank Fickl, Bernd Cebulski, and Jens Liebold, entitled: Highly Integrative and Flexible Electric Drive Unit for E-Vehicles. This article describes a drive unit for one axle of a vehicle. It includes an electric motor arranged concentrically and coaxially with a bevel gear differential. A switchable 2-speed planetary gear set is arranged in the power train between the electric motor and the bevel gear differential, which is also positioned coaxially with the electric motor or the bevel gear differential or spur gear differential. The drive unit is very compact and, thanks to the switchable 2-speed planetary gear set, allows a good compromise between climbing ability, acceleration, and energy consumption.Such drive units are also referred to as e-axles or electrically operated drive trains.

[0004] In addition to purely electric drivetrains, hybrid drivetrains are also known. Such drivetrains in hybrid vehicles typically comprise a combination of an internal combustion engine and an electric motor, enabling purely electric operation—for example, in urban areas—while maintaining sufficient range and availability, especially for long-distance journeys. Furthermore, in certain operating situations, it is possible to use both the internal combustion engine and the electric motor simultaneously.

[0005] In the development of electric motors intended for electric axles or hybrid modules, there is a continuing need to increase their power densities, making the necessary cooling of the electric motors increasingly important. Due to the necessary cooling performance, hydraulic fluids, such as cooling oils, have become the preferred solution in most concepts for dissipating heat from the thermally stressed areas of an electric motor.

[0006] Jacket cooling and winding head cooling, for example, are known from the state of the art for cooling electrical machines using hydraulic fluids. While jacket cooling transfers the heat generated on the outer surface of the stator core into a cooling circuit, with winding head cooling, the heat is transferred directly to the fluid at the conductors outside the stator core in the area of ​​the winding heads.

[0007] Further improvements are provided by separately designed cooling channels, which are incorporated both into the laminated core of the stator (see e.g. EP 3 157 138 A1) and into the slot in addition to the conductors (see e.g. Markus Schiefer: Indirect winding cooling of highly utilized permanent magnet synchronous machines with tooth coil winding, dissertation, Karlsruhe Institute of Technology (KIT), 2017).

[0008] Concepts are also known in which hydraulic fluid flows directly around the windings to increase power density. Improved cooling with direct contact between hydraulic fluid and the conductor in the slot is already known in principle from the prior art. For example, DE 10 2015 013 018 A1 describes a solution for electrical machines with single-tooth windings, in which the fluid flows directly around the windings wound around the teeth.

[0009] From EP 1 367 690 A2 an electrical machine according to the preamble of claim 1 is known.

[0010] For further prior art, reference is made to WO 2019 / 241765 A1.

[0011] The object of the invention is to provide an electrical machine that has a high power density through optimized cooling and an optimized electromagnetic design. Furthermore, the object of the invention is to ensure that the electrical machine is cost-effective to manufacture and easy to install.

[0012] This object is achieved by an electrical machine, in particular for an electrically operated drive train of a motor vehicle, comprising a rotor which is rotatably mounted relative to a stator, the rotor having a rotor shaft with at least one first rotor body which is arranged on the rotor shaft in a rotationally and displacement-proof manner, the stator comprising a first stator body and a second stator body which are spaced apart from one another and the first stator body has a first stator winding and the second stator body has a second stator winding, the first stator winding being arranged within a first hydraulic chamber or wet chamber and the second stator winding being arranged within a second hydraulic chamber or wet chamber, within which the respective stator windings are each supplied with a hydraulic fluid orFluid can be contacted at least in sections, wherein the electrical machine comprises a hydraulic connecting element which hydraulically connects the first hydraulic chamber to the second hydraulic chamber, wherein at least one electrical conductor of the first stator winding and / or the second stator winding is arranged within the hydraulic connecting element.

[0013] The hydraulic connecting element can have any desired closed cross-sectional geometry and can be designed, for example, as a tube or hose for bridging one or more joints between a first hydraulic chamber of a first stator body and a second hydraulic chamber of a second stator body. This hydraulic connecting element also ensures that the electrical conductor of a stator winding is guided within it and simultaneously surrounded by the coolant. By selecting the right material for the hydraulic connecting element and a corresponding wall thickness, an electrical insulation effect against electrically conductive housing parts can be achieved. The hydraulic connecting element can preferably be inserted or fitted into existing openings. Furthermore, the hydraulic connecting element can be used to adjust air and creepage distances within the electrical machine.

[0014] The sealing effect of the hydraulic connecting element with adjacent housing parts can be achieved, for example, by a defined gap between the sealing element and the housing, by pressing the hydraulic connecting element in the sealing area with adjacent housing parts, or by using a separate sealing element or sealant. The sealing element can preferably also be integrated into the hydraulic connecting element for a sealed and electrically insulated feedthrough.

[0015] First, the individual elements of the claimed subject matter of the invention are explained in the order in which they appear in the set of claims, and subsequently, particularly preferred embodiments of the subject matter of the invention are described.

[0016] Electrical machines are used to convert electrical energy into mechanical energy and / or vice versa, and generally comprise a stationary part known as a stator, stand or armature, and a part known as a rotor or rotor, which is arranged to be movable relative to the stationary part. In the case of electrical machines designed as rotating machines, a distinction is made in particular between radial flux machines and axial flux machines. A radial flux machine is characterized in that the magnetic field lines in the air gap formed between the rotor and stator extend in the radial direction, whereas in the case of an axial flux machine the magnetic field lines in the air gap formed between the rotor and stator extend in the axial direction. The electrical machine according to the invention can be designed as an axial flux machine or a radial flux machine.

[0017] The stator of the electrical machine can in particular be designed as a stator for a radial flux machine. The stator of a radial flux machine is usually cylindrical and preferably consists of electrically insulated, layered, and stacked laminations. Distributed around the circumference, grooves and / or channels can be cut into the electrical lamination, running parallel to the rotor shaft, to accommodate the stator winding or parts of the stator winding. The stator designed for a radial flux machine can be designed as a stator for an inner rotor or an outer rotor. In an inner rotor, for example, the stator teeth extend radially inwards, while in an outer rotor they extend radially outwards.

[0018] The electric machine according to the invention is intended in particular for use within a drive train of a hybrid or fully electric motor vehicle. In particular, the electric machine is dimensioned such that vehicle speeds greater than 50 km / h, preferably greater than 80 km / h, and in particular greater than 100 km / h can be achieved. The electric machine particularly preferably has an output greater than 30 kW, preferably greater than 50 kW, and in particular greater than 70 kW. It is further preferred that the electric machine provides rotational speeds greater than 5,000 rpm or 1 / min, particularly preferably greater than 10,000 rpm, and most preferably greater than 12,500 rpm.

[0019] A stator winding is an electrically conductive conductor whose longitudinal extent is significantly greater than its extent perpendicular to the longitudinal extent. The stator winding can, in principle, have any desired cross-sectional shape. Rectangular cross-sectional shapes are preferred, as these allow high packing and, consequently, power densities to be achieved. A stator winding is particularly preferably made of copper. A stator winding preferably has insulation. To insulate the stator winding, for example, mica paper, which for mechanical reasons can be reinforced with a glass fabric carrier, can be wound in strip form around one or more stator windings that are impregnated with a curing resin. In principle, it is also possible to use a curable polymer or a lacquer layer without mica paper to insulate a stator winding.

[0020] According to an advantageous embodiment of the invention, it can be provided that the electrical machine is designed as an axial flux machine, comprising the rotor rotatably mounted relative to the stator in a dry space, wherein the rotor has the rotor shaft with at least the first disc-shaped rotor body arranged on the rotor shaft in a rotationally and displacement-resistant manner, wherein the stator comprises the first annular disc-shaped stator body and the second annular disc-shaped stator body, which are arranged coaxially to one another and to the rotor shaft and are axially spaced from one another with the rotor arranged therebetween. The advantage of this embodiment is that the electrical machine can thus be designed to be very compact axially.

[0021] The magnetic flux in such an electric axial flux machine (AFM), such as an electric drive machine of a motor vehicle designed as an axial flux machine, is directed axially to a direction of rotation of the rotor of the axial flux machine in the air gap between stator and rotor. There are different types of axial flux machines. One known type is a so-called I-arrangement, in which the rotor is arranged axially next to a stator or between two stators. Another known type is a so-called H-arrangement, in which two rotors are arranged on opposite axial sides of a stator. In the context of the present invention, an I-arrangement is preferred.

[0022] According to a further preferred development of the invention, the hydraulic connecting element can also be formed from an electrically non-conductive material. This can provide good electrical insulation from electrically conductive components of the electrical machine.

[0023] Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the hydraulic connecting element has a substantially cylindrical ring-like spatial shape.

[0024] According to a further particularly preferred embodiment of the invention, it can be provided that the hydraulic connecting element is positioned radially above the first stator body and / or the second stator body.

[0025] Furthermore, the invention can also be further developed in that the hydraulic connecting element has a first seal which seals the first hydraulic chamber from the dry chamber of the rotor and / or the hydraulic connecting element has a second seal which seals the second hydraulic chamber from the dry chamber of the rotor. In In a likewise preferred embodiment variant of the invention, it can also be provided in this context that the first seal and / or the second seal are / is formed integrally with the hydraulic connecting element.

[0026] It may also be advantageous to further develop the invention in such a way that the hydraulic connecting element is connected by means of a press fit to a first housing component that at least partially delimits the first hydraulic chamber and / or the hydraulic connecting element is connected by means of a press fit to a second housing component that at least partially delimits the second hydraulic chamber.

[0027] According to a further preferred embodiment of the subject matter of the invention, it can be provided that a plurality of hydraulic connecting elements are arranged circumferentially distributed between the first hydraulic chamber and the second hydraulic chamber.

[0028] Finally, the invention can also be advantageously designed such that the hydraulic connecting elements are designed to be substantially identical, whereby the component complexity and thus the manufacturing costs of the electrical machine can be reduced.

[0029] It is also preferable that the winding ends of the axial flux machine run in such a way that, during assembly, the winding ends are oriented parallel or approximately parallel to the main machine axis. During assembly, the winding ends are preferably guided to one of the end faces of the axial flux machine through specially designed and appropriately designed local clearances in the axial flux machine and, after the corresponding machine parts have been pushed together axially, are suitably electrically and mechanically connected. The stator winding ends connected in this way are particularly preferably guided to the end faces via connecting conductors to the axially positioned phase connections. These connecting conductors can connect seamlessly to the winding through the winding ends or can be suitably electrically and mechanically connected to the winding.The star points of the machine are preferably not extended to the phase connection.

[0030] To provide electrical contact between a wet space and a dry space of the electrical machine, at least one electrical connection element can particularly preferably be provided. For this purpose, the electrical connection element has a contacting body which is fixed in a receiving sleeve by means of a press fit. In particular, it can be provided to use a bolt pressed into the receiving sleeve or a threaded bushing as the contacting body, the main function of which is to support the clamping forces, for example via the load-bearing cross-section and an undercut. The material of the bolt or the threaded bushing advantageously has a higher mechanical load-bearing capacity (yield point) than the material of the receiving sleeve. The receiving sleeve, in turn, preferably has a higher specific electrical conductivity compared to the contacting body.However, the material of the receiving sleeve is softer and therefore has a lower mechanical load capacity (yield point) than the material of the contact body.

[0031] The contacting body, designed as a bolt or threaded bushing, is preferably pressed into the housing component in such a way that the softer material is elastically and plastically deformed, so that the sealing effect is sufficient to seal the two spaces on either side of the housing component from each other or to seal one space from the environment. For this purpose, a cross-sectional widening is particularly preferably provided on the contacting body, for example on the bolt or threaded bushing, which is designed for the deformation of the softer material. The elastic part of the deformation ensures that the contact pressure is maintained and the plastic part of the deformation extends the sealing sections in the area provided for this purpose. Excess material of the counterpart is absorbed in a designated area. At the same time, the cross-sectional widening of the contacting body, for example the bolt orThe threaded bushing has an undercut that counteracts the pull-out of the receiving sleeve. The space for absorbing excess material during the pressing process can also be preferably filled with additional sealants or sealing elements, thus further enhancing the sealing effect.

[0032] The receiving sleeve with the pressed-in contact body, for example, the bolt or threaded bushing, is particularly preferably mounted in the housing component in an electrically insulated manner. For this purpose, the housing component can either be made of a poorly electrically conductive material or an insulating material, or it can be inserted into an electrically non-conductive adapter that provides the electrical insulation between the housing component and the assembly of contact body and receiving sleeve. The sealing effect can be achieved, for example, by sealing elements between the receiving sleeve and the adjacent housing component or adapter.

[0033] The invention will be explained in more detail below with reference to figures without limiting the general inventive concept.

[0034] They show: Figure 1 an electric axial flux machine in a schematic axial sectional view, Figure 2an electric axial flux machine in a perspective exploded view, and Figure 3 a motor vehicle with an electrical machine in schematic block diagrams.

[0035] The Figure 1 shows an electric machine 1 for an electrically operated drive train 10 of a motor vehicle 11, as shown by way of example in the Figure 3 In the upper illustration of the Figure 3 the drive train 10 of a hybrid-powered motor vehicle and, in the lower illustration, a fully electrically powered motor vehicle 11, each with an electric machine 1, is shown.

[0036] The electric machine 1 comprises a rotor 3 which is rotatably mounted relative to a stator 2, wherein the rotor 3 has a rotor shaft 30 with at least one first rotor body 31 which is arranged on the rotor shaft 30 in a rotationally and displacement-proof manner. The stator 2 has a first stator body 21 and a second stator body 22 which are spaced apart from one another in the axial direction, wherein the first stator body 21 has a first stator winding 41 and the second stator body 22 has a second stator winding 42, wherein the first stator winding 41 is arranged within a first hydraulic chamber 51 and the second stator winding 42 is arranged within a second hydraulic chamber 52, within which the respective stator windings 41, 42 can each be contacted by a hydraulic fluid 5, at least in sections.

[0037] The electric machine 1 further comprises a plurality of hydraulic connecting elements 6, which hydraulically connect the first hydraulic chamber 51 to the second hydraulic chamber 52. At least one electrical conductor 7 of the second stator winding 42 is arranged within each of the hydraulic connecting elements 6. The plurality of substantially identically designed hydraulic connecting elements 6 are arranged circumferentially distributed between the first hydraulic chamber 51 and the second hydraulic chamber 52, which can be seen particularly well from the synopsis of Figure 1 with the Figure 2 becomes apparent.

[0038] From the Figure 1It can also be seen that the electrical machine is designed as an axial flux machine 1 with the rotor 3 which is mounted rotatably relative to the stator 2 in a dry space 32. The rotor 3 comprises the rotor shaft 30 with at least the first disc-shaped rotor body 31 which is arranged on the rotor shaft 30 in a rotationally and displacement-proof manner. The stator 2 has the first annular disc-shaped stator body 21 and the second annular disc-shaped stator body 22, which are arranged coaxially to one another and to the rotor shaft 30 and are axially spaced from one another with the rotor 3 arranged therebetween.

[0039] The first stator winding 41 has first winding ends emerging from the first stator body 21, which extend radially above the stator body 21 in the axial direction. The second stator winding 42 also has second winding ends emerging from the second stator body 22, which extend radially above the first stator body 21 and the second stator body 22 in the axial direction. From the synopsis of Figure 1 with the Figure 2 It is further apparent that the first hydraulic chamber 51 is at least partially enclosed by a delimiting first housing component 91, which has a plurality of circumferentially distributed openings for the passage of the second winding ends.

[0040] The first winding ends are arranged on a circular path with a first diameter and the second winding ends are arranged on a circular path with a second diameter, wherein the first diameter is different from the second diameter.

[0041] The first winding ends and the second winding ends are oriented toward the same axial end face of the axial flux machine 1 and are connected to the same axial end face of the axial flux machine 1. The first stator winding 41 and the second stator winding 42 are each configured as three-phase with a star-point connection.

[0042] The hydraulic connecting element 6 is formed from an electrically non-conductive material and has a substantially cylindrical ring-like spatial shape. In the embodiment shown, the hydraulic connecting elements 6 are positioned radially above the first stator body 21 and the second stator body 22.

[0043] In the Figure 2It is further shown that a hydraulic connecting element 6 has a first seal 81 which seals the first hydraulic chamber 51 from the dry chamber 32 of the rotor 2, and the hydraulic connecting element 6 has a second seal 82 which seals the second hydraulic chamber 52 from the dry chamber 32 of the rotor 2. The first seal 81 and the second seal 82 are designed as sealing rings in the embodiment shown, which is particularly evident from the Figure 2 is evident.

[0044] The hydraulic connecting elements 6 are each connected by means of a press fit to a first housing component 91 which at least partially delimits the first hydraulic chamber 51 and to a second housing component 92 which at least partially delimits the second hydraulic chamber 52. List of reference symbols

[0045] 1 electric machine 2 stator 3 rotor 4 stator winding 5 hydraulic fluid 6 connecting element 7 conductor 8 seal 9 housing component 10 drive train 11 motor vehicle 21 stator body 22 stator body 30 rotor shaft 31 rotor body 32 dry chamber 41 stator winding 42 stator winding 51 hydraulic chamber 52 hydraulic chamber 81 seal 82 seal 91 housing component 92 housing component

Claims

1. An electric machine (1), in particular for an electrically operated drive train of a motor vehicle, comprising a rotor (3) which is rotatably mounted relative to a stator (2), wherein the rotor (3) has a rotor shaft (30) with at least one first rotor body (31) arranged on the rotor shaft (30) in a non-rotatable and non-displaceable manner, wherein the stator (2) comprises a first stator body (21) and a second stator body (22) which are spaced apart from one another, and the first stator body (21) has a first stator winding (41) and the second stator body (22) has a second stator winding (42), wherein the first stator winding (41) is arranged within a first hydraulic chamber (51) and the second stator winding (42) is arranged within a second hydraulic chamber (52), within which the respective stator windings (41, 42) can each be contacted by a hydraulic fluid (5) at least in sections, characterized in that the electric machine (1) comprises a hydraulic connecting element (6), which hydraulically connects the first hydraulic chamber (51) to the second hydraulic chamber (52), wherein at least one electrical conductor (7) of the first stator winding (41) and / or the second stator winding (42) is arranged within the hydraulic connecting element (6).

2. The electric machine (1) according to claim 1, characterized in that the electric machine is designed as an axial flux machine (1), comprising the rotor (3) which is rotatably mounted in a dry chamber (32) relative to the stator (2), wherein the rotor (3) has the rotor shaft (30) with at least one first disk-shaped rotor body (31) arranged on the rotor shaft (30) in a non-rotatable and non-displaceable manner, wherein the stator (2) comprises the first annular disk-shaped stator body (21) and the second annular disk-shaped stator body (22), which are arranged coaxially to one another and to the rotor shaft (30) and are axially spaced from one another with the rotor (3) arranged therebetween.

3. The electric machine (1) according to any one of the preceding claims, characterized in that the hydraulic connecting element (6) is made of an electrically non-conductive material.

4. The electric machine (1) according to any one of the preceding claims, characterized in that the hydraulic connecting element (6) has a substantially cylindrical ring-like spatial shape.

5. The electric machine (1) according to any one of the preceding claims, characterized in that the hydraulic connecting element (6) is positioned radially above the first stator body (21) and / or the second stator body (22).

6. The electric machine (1) according to any one of the preceding claims, characterized in that the hydraulic connecting element (6) has a first seal (81) which seals the first hydraulic chamber (51) from the dry chamber (32) of the rotor (3) and / or the hydraulic connecting element (6) has a second seal (82), which seals the second hydraulic chamber (52) from the dry chamber (32) of the rotor (3).

7. The electric machine (1) according to claim 6, characterized in that the first seal (81) and / or the second seal (82) is formed integrally with the hydraulic connecting element (6).

8. The electric machine (1) according to any one of the preceding claims, characterized in that the hydraulic connecting element (6) is connected by means of a press fit to a first housing component (91) which delimits the first hydraulic chamber (51) at least in sections and / or the hydraulic connecting element (6) is connected by means of a press fit to a second housing component (92) which delimits the second hydraulic chamber (52) at least in sections.

9. The electric machine (1) according to any one of the preceding claims, characterized in that a plurality of hydraulic connecting elements (6) are arranged circumferentially distributed between the first hydraulic chamber (51) and the second hydraulic chamber (52).

10. The electric machine (1) according to any one of the preceding claims, characterized in that the hydraulic connecting elements (6) are designed substantially identical.