Electric machine, in particular electric motor, and method for braking an electric machine

Abstract

Electric machine (10, 100a, 400), containing: a ring-shaped stator carrier (12), a ring-shaped rotor carrier (14) having an inner diameter (D1) that is larger than an outer diameter (D2) of the stator carrier (12) and which is arranged concentrically or coaxially with the stator carrier (12) on an axis of rotation (A), a wet-running multi-disc brake (16) arranged on the stator carrier (12) and on the rotor carrier (14), which is arranged in an oil-filled installation space (88), a sealing element (44) that closes off the oil-filled installation space (88) to an outside of the electric machine (10, 100a, 400), wherein a first number of brake plates (70 to 76) of the multi-plate brake (16) is arranged on a receiving part (21) of the stator carrier (12), and wherein the receiving part (21) is formed integrally with the stator carrier (12).

Description

[0001] The invention relates to an electric machine, in particular an electric motor, which is especially suitable as a wheel hub drive, for example for an electric vehicle or for a hybrid vehicle with an electric drive and a conventional combustion engine. However, other applications of the electric machine are also possible, as will be explained in more detail below.

[0002] DE 198 15 962 A1 describes an electric machine with a stator support, a rotor support and a lamellar brake arranged on the stator support and on the stator carrier.

[0003] DE 199 58 545 C1 discloses a gearless elevator machine with a synchronous external rotor motor. To achieve a narrow design, the interior space created by the external rotor construction is used, among other things, to house a brake and a measuring system.

[0004] From DE 10 2004 032 167 A1, a drive device with a wet-running brake is known, in which the brake rotor is provided with teeth on its outer circumference. These teeth act as pulse generators for a speed sensor, thereby integrating the sensor's pulse generator rotor into the brake.

[0005] DE 10 2010 008 230 A1 describes a drive wheel with a wheel hub motor and a brake, which are cooled via a common cooling circuit. The cooling fluid is forcibly guided through channels in the wheel hub motor and subsequently through parts of the brake, which is designed as a disc brake.

[0006] The invention relates to an electric machine, in particular an electric motor, especially for a wheel hub drive, comprising: - a ring-shaped stator support, - a ring-shaped rotor carrier which has an inner diameter that is larger than an outer diameter of the stator carrier and which is arranged concentrically or coaxially with the stator carrier on an axis of rotation, and - a wet-running multi-disc brake arranged on the stator carrier and the rotor hub, which is arranged in an oil-filled installation space, a sealing element that closes off the oil-filled installation space to an outside of the electric machine, wherein a first number of brake discs of the multi-disc brake is arranged on a receiving part of the stator carrier, and wherein the receiving part is formed integrally with the stator carrier.

[0007] The invention also relates to a method for braking an electric machine or an electric motor, in particular the electric motor mentioned above, comprising: - Arranging a multi-disc brake on a stator carrier and a rotor carrier of an electric machine, - Arranging an actuating element of the multi-disc brake on at least one disc of the multi-disc brake, - Sealing the multi-disc brake with a sealing element that closes off an installation space in which the multi-disc brake is arranged to an outside of the electric machine, - Filling the multi-disc brake with a fluid, especially permanently, and - Actuating the multi-disc brake to brake the electric motor, especially repeatedly.

[0008] The objective of further developments of the invention is to provide a compact assembly of electric motor and brake that is well sealed against the ingress of dirt, dust, water, etc. Furthermore, an associated method for braking and sealing an electric motor is to be provided.

[0009] This problem is solved for an electric machine or electric motor by the electric machine or electric motor according to claim 1 and for a method by the method specified in dependent claim 14. Further developments are specified in the dependent claims.

[0010] The electric machine, in particular the electric motor, especially the electric motor for a wheel hub drive, may contain: - a ring-shaped stator support, - an annular rotor carrier having an inner diameter larger than the outer diameter of the stator carrier and arranged concentrically or coaxially with the stator carrier on an axis of rotation, and - a multi-plate brake arranged on the stator carrier and the rotor carrier, wherein a first number of brake plates of the multi-plate brake are arranged on a receiving part of the stator carrier, and wherein preferably the receiving part is formed integrally with the stator carrier.

[0011] The electric motor can be a vehicle's traction motor. It can also be used in motor mode and generator mode. Other applications are listed below. A generator with the same characteristics can also be used instead of an electric motor, for example, a generator (e.g., direct drive) for wind turbines, especially for turbines with a tower height greater than 50 meters or greater than 100 meters.

[0012] A second set of brake plates for the multi-plate brake can be arranged on the rotor carrier. For example, 3 to 10 pairs of plates can be used. The plates can have a radial dimension ranging from 2 centimeters to 10 centimeters.

[0013] Permanent magnets can be arranged on the rotor carrier, for example. Alternatively, a magnetic field can be generated on the rotor in another way.

[0014] Windings can be arranged around soft magnetic laminations, such as dynamo steel, on the stator support. The iron, for example, has a non-linear magnetization characteristic with a saturation curve. High flux densities can be generated easily with relatively moderate currents using this soft magnetic iron. The laminations can be insulated from each other to prevent eddy currents and the associated losses.

[0015] An air gap can exist between the stator and rotor supports. This air gap is highly magnetized due to the strong magnetic field present in the air gap, generated by the current-carrying conductors of the stator. An air gap torque is produced at the rotor because this magnetic field acts on the rotor's permanent magnets. Alternatively, other motor types can be used, such as asynchronous motors, where the rotor magnetic field is generated by induction in rods or windings of the rotor; DC motors, for example, with slip rings and / or brushes; reluctance motors; permanent magnet motors with a high reluctance component; and so on.

[0016] The ring-shaped design of the rotor carrier or rotor and the stator carrier or stator allows for a low weight, so that the unsprung mass of a vehicle is as small as possible, which leads to good driving characteristics.

[0017] The receiving element can be arranged parallel to the axis of rotation next to the stator carrier. This allows both the stator carrier and the multi-disc brake to be positioned as far outwards as possible in the radial direction to generate the highest possible drive torque and braking torque, respectively.

[0018] The receiving element can have a larger radial dimension than the stator carrier or a main part of the stator carrier, in particular an dimension that is at least twice or at least three times the radial dimension of the stator carrier. This allows braking forces to be absorbed more effectively by the stator.

[0019] At least one support element, in particular a side wall or several support struts, can be arranged between the mounting part and an inner ring of the electric motor. This support element can be arranged at an angle to the axis of rotation. The smaller angle between the support element (e.g., the inner or outer surface and the axis of rotation) is, for example, in the range of 45 to 80 degrees. This creates a cavity suitable for accommodating control arms or wheel carriers.

[0020] The inner ring can also be arranged concentrically to the axis of rotation. The stator carrier, support element, and inner ring can be formed in one piece, e.g., as a casting.

[0021] The at least one support element can be a first support element. At least one second support element can be provided, in particular a second support wall or several second support struts, which can be arranged between the stator support and the inner ring.

[0022] A first distance in the axial direction between the at least one first support element and the at least one second support element can be at least twice as large at a first radius as a second distance between these parts at a second radius that lies further inwards than the first radius.

[0023] The second support element can also serve to absorb forces and support the stator carrier. Both support elements, the inner ring and the stator carrier, can form a housing, in particular a closed housing and / or a one-piece housing. The control electronics, especially the power electronics of the motor or machine, can be arranged in the housing. The control electronics can, for example, be accessible or replaceable via one or more removable openings. For example, the liquid cooling system provided for the electric machine can also be used for the control electronics.

[0024] Inside the inner ring, at least one bearing can be arranged for the rotatable mounting of the rotor carrier on the stator carrier. For example, a helically preloaded double tapered roller bearing or other double bearings can be used. Alternatively, a simple grooved bearing can be used, whose rolling elements are, for example, balls, rollers, or cones.

[0025] The multi-disc brake can be a wet brake, preferably arranged in an oil-filled housing. This housing can be sealed off from the outside of the electric motor by a sealing element, in particular a shaft seal. This sealing element prevents the release of particulate matter into the environment from the brake. Furthermore, it prevents corrosion of the brake, especially when the multi-disc brake is used only infrequently, for example, because braking is primarily achieved through recuperation, i.e., the regenerative operation of the electric motor.

[0026] In one design, the oil can have a temperature resistance of, for example, 300 degrees Celsius, 250 degrees Celsius, or 200 degrees Celsius. This temperature can be matched to the temperature resistance of any magnets present on the stator. The oil should generate the lowest possible coefficient of friction. Therefore, low-viscosity oils can be used, which result in low drag torques and allow for easy tearing of the oil film. Additives can be added to the oil to enhance these properties.

[0027] The encapsulated multi-disc brake can be designed as a so-called lifetime brake, particularly if, for example, it is only occasionally used as a generator brake for the electric motor. This means that, under normal circumstances, no maintenance is required over the entire lifetime of the vehicle or other machine, possibly only one or more oil changes. The service life can be, for example, at least 10 years.

[0028] In one design, a lining can be used that is, for example, also matched to the specified temperatures and / or the oil itself. The lining can be attached to one or both sides of the inner and / or outer plates. The plates can be made of steel. The lining can be plastic-based, for example, with added particles that increase friction. The inner plates can be thinner than the outer plates, and, for example, only the inner plates can be coated with brake linings on one or both sides.

[0029] The oil-filled installation space can be sealed against an air gap located between the stator carrier and the rotor carrier by a further seal, with the rotor torque being generated in this air gap. The further seal preferably has a larger diameter than the sealing element that seals to the outside. Alternatively, both seals can have the same diameter, in particular a diameter that is at least 10 percent or at least 20 percent smaller than the outer diameter of the stator carrier, especially at the air gap of the electric motor.

[0030] However, one design allows for construction without a second sealing element. In this case, oil is present in the air gap and may even reach the rotor or rotor carrier bearing.

[0031] In another design, the second seal has a larger diameter than the first seal. This reduces the frictional forces occurring during rotation, at least in one of the seals.

[0032] For information on the design of the seals, please refer to the catalog of the company Freudenberg Simrit mentioned below.

[0033] A vehicle wheel can be driven directly by the electric motor, particularly without the use of a gearbox. The vehicle wheel, or rather one of its tires, is in contact with the road surface and serves to propel the vehicle. Using the specified wheel hub motor allows for a simpler vehicle design. The wheel hub motor can be electronically controlled via a frequency converter or inverter.

[0034] Alternatively, a gearbox can be provided between the electric motor and the wheel or tire. Viewed from the direction of power flow while driving, the gearbox can be located behind the multi-disc brake. This allows the gearbox to increase the braking torque.

[0035] An actuating element of the multi-disc brake can contain a ball ramp actuator or at least one hydraulic piston. The ball ramp actuator or the piston can act directly on the discs. The actuating element can be arranged on the stator carrier.

[0036] A ball ramp actuator requires minimal space in the axial direction. The ball ramp actuator can contain two rings. At least one of the rings can have a ramp. Balls or other rolling elements are mounted in corresponding grooves between the rings. To actuate the brake, the two rings are rotated relative to each other, creating a gap between them or widening an existing gap, which compresses the plates. For example, only one ring may be moved during actuation.

[0037] The ball ramp actuator itself can in turn be actuated by a hydraulic piston or in another way, i.e. by twisting the rings relative to each other.

[0038] The electric motor can be connected to a rim, which in turn is connected to the rotor carrier and includes a sidewall or side struts leading to a rim disc. The rim serves to accommodate a tire, particularly an air-filled tire. Alternatively, the tire or an "outer rim" can also be mounted directly on the periphery or circumference of the rotor carrier.

[0039] The rated power of the electric machine, especially the electric motor, can be less than 150 kilowatts. Alternatively, the rated power of the electric machine, especially the electric motor, can also be greater than 150 kilowatts. The rated power is the key parameter for the design of the electric motor or electric machine and is usually specified on the machine's nameplate.

[0040] Rated power outputs below 150 kilowatts can be used, for example, for passenger vehicles approved for fewer than 7 or 6 people. Rated power outputs greater than 150 kilowatts or greater than 200 kilowatts can be used for heavy-duty vehicles, e.g., in mining, agriculture, etc., especially for mining trucks, tractors, and agricultural vehicles.

[0041] Both of the aforementioned rated power ranges can also be relevant for the winches of cranes or elevators.

[0042] Both of these areas are also relevant for the generators of wind turbines.

[0043] The electric motor can be used for the wheel hub drive of a passenger vehicle, particularly one approved for fewer than 7 or fewer than 6 passengers. The advantages gained through its excellent sealing and compact design make it suitable for this application.

[0044] The stator carrier can have an inner diameter ranging from 30 to 50 centimeters. The outer diameter of the stator carrier can preferably be no more than 2 centimeters, no more than 3 centimeters, or no more than 6 centimeters larger than the inner diameter of the stator carrier. These dimensions result in a low weight for the electric motor, which in turn leads to good vehicle handling characteristics due to low unsprung mass.

[0045] The design of the electric motor and the multi-disc brake is also determined based on the diameter.

[0046] A method for braking an electric machine, in particular an electric motor, especially an electric motor according to one of the preceding explanations, may include: - Arranging a multi-disc brake on a stator carrier and on a rotor carrier of an electric machine, - Arranging an actuating element of the multi-disc brake on the discs of the multi-disc brake, - Sealing the multi-disc brake with at least one seal or exactly one seal, - Filling the multi-disc brake with a fluid, especially permanently, and - Activating the multi-disc brake to brake the electric motor.

[0047] Regarding filling, it can be the case that the brake is constantly or permanently filled with oil to achieve, for example, short response times, such as less than 50 or less than 10 milliseconds. However, only intermittent filling may be appropriate in certain applications, such as multi-stage torque converters or retarders, particularly on trucks and similar large vehicles where braking times down to the millisecond are not critical. If the oil is not in the multi-disc brake, so-called drag losses can be reduced, for example.

[0048] More precisely, braking slows the rotation of the rotor of an electric motor, and thus also, for example, a vehicle powered by the electric motor. The fluid can be machine oil, see the explanations above.

[0049] When the multi-disc brake is applied, the electric motor can simultaneously operate in generator mode to increase braking power. Alternatively, the multi-disc brake can also be applied while the motor is running, i.e., without the generator.

[0050] Separate cooling circuits can be used for the multi-disc brake and for the stator windings. Water jacket cooling can be used for the stator windings.

[0051] Alternatively, a common cooling circuit can be used for the multi-disc brake and for the stator windings, especially if oil is also permitted in the air gap of the electric motor.

[0052] In other words, in addition to general electric motors, a wheel hub drive with a perimeter disc brake is specified. Due to their design, wheel hub motors as direct drives require a seal with a larger diameter than standard electric drives. Specifically, the external rotor design of the wheel hub motor results in a larger seal diameter. However, the external rotor design has the advantage of allowing optimal utilization of the rim diameter to generate torque. Furthermore, wheel hub motors, due to their position within the wheel, are extremely exposed to water and similar media. They must be immersion-proof and simultaneously withstand high splash pressures. This means the seal must provide a very tight seal both at high rotational speeds and when stationary. The sealing challenge is exacerbated when, for example, air must be sealed against air, rather than air against oil as in a gearbox.

[0053] Integrating the motor, brake and power electronics proves difficult due to the limited installation space.

[0054] This remains an open question with such drives. The company Protean, for example, addresses the problem by allowing their drive to be flooded and then potting or sealing the windings and electrical components. However, any water that gets in could freeze, and the ice could damage the motor. Practical proof that a wheel hub drive is watertight for high speeds, such as in passenger cars, is currently lacking.

[0055] For example, Schaeffler incorporates a drum brake into one of its wheel hub drives, but this is not intended for continuous operation; it serves only as a backup solution. Michelin and other manufacturers do not drive the wheel directly, but instead transmit torque and power via a gearbox.

[0056] A wheel hub drive with an external rotor as a direct drive is proposed. A multi-disc brake, designed as a perimeter brake, is used. A perimeter brake means the brake is not connected to the wheel hub but to the rim, i.e., to the outer rotor of the drive. Therefore, the brake is preferably designed as a ring rather than a disc. A multi-disc brake can run in oil; see, for example... Fig. 1, Fig. 2 to Fig. 3. The oil-immersed and oil-cooled lamellar assembly is sealed, for example, by two seals. One seal protects the lamellar assembly from the outside, while a second internal seal protects it from the electric motor.

[0057] Due to this design, the diameter of the seal to the outside can be reduced because the brake surrounds the motor or machine, i.e., it is located on its periphery. The oil-filled reservoir then lies above the gap to be sealed. The seal is achieved, for example, with two gaskets, one separating air from oil. Fig. 1, Fig. 2 to Fig. 3. The outer seal has a reduced diameter. Alternatively, seals with the same diameter can be used. In the illustrated embodiment, the inner seal has a larger diameter.

[0058] In an alternative embodiment, the diameter of the inner seal can be reduced by, for example, positioning the actuator centrally in the lamellar pack or between the lamellae of the lamellar pack and simultaneously pressing both lamellar pack halves or parts axially outwards against the surrounding rotating part.

[0059] Nevertheless, the sealing effect is easier to achieve with the proposed solutions because air is sealed against oil and because the harmful media must first penetrate through the oil.

[0060] For example, if a ball ramp actuator is used, the resulting installation space in the axial direction is small.

[0061] The ring-shaped design of the brake allows wishbones to be guided into the interior of the wheel bowl.

[0062] Other technical effects include: The multi-plate brake is located above the gap to be sealed. An oil-filled reservoir lies between the engine compartment and the exterior. - The ring-shaped housing for the multi-disc brake can reduce the diameter of the critical seal. Due to the smaller diameter, the web speed for which the seal must be designed is reduced. If dirt enters the drive system, it first enters the oil-filled chamber and can be filtered out again via an oil circuit. The heat generated during braking, briefly exceeding 100 kilowatts, can be dissipated via the oil and reused in the vehicle. - The majority of the heat, for example, is not released into the ambient air as with standard friction brakes (disc brake, drum brake) and is not lost. - By designing the brake as a perimeter brake, the wheel hub drive can be mounted on various chassis concepts because the control arms can engage within the wheel disc. This allows such a design to be used for multiple axles (e.g., front and / or rear) and axle systems simultaneously. - The larger diameter of the disc pack compared to a compact axle-mounted disc brake leads to higher path speeds, which means that higher braking performance or braking torque can be achieved with the same contact pressure and friction surface. - Furthermore, the larger lamellar pack diameter improves the heat dissipation and cooling of the brake, as the rotor-side lamellars, in addition to oil cooling, also allow for heat dissipation and heat removal to the outside air via a short path.

[0063] Common sealing materials are suitable for the seals; see, for example, Technical Handbook 2007, Freudenberg Simrit GmbH & Co. KG, pages 34 and 35. For example, FKM (fluoroelastomers) may be suitable due to its abrasion resistance, temperature resistance, and / or oil resistance. If permanent magnets are used in the rotor, the oil temperature, and therefore also the temperature at the seal, should be below approximately 200 degrees Celsius to ensure the permanent magnetization of the magnets.

[0064] The design of the sealing lip, in particular the angles on the oil side and on the air side, are described, for example, on page 25 of the aforementioned catalog, i.e., 35 to 60 degrees of angle on the oil side and 12 to 30 degrees of angle on the air side.

[0065] The tension spring rings of the seal(s) can be arranged within the oil bath and oriented towards the plates of the multi-plate brake, see e.g. Fig. (page 21) and Fig. (Page 22) of the catalog. Alternatively, one or more seals with a compression spring ring can be used.

[0066] Alternatively, seals from other manufacturers can be used, for which similar or different design criteria apply.

[0067] The multi-disc brake can be designed according to common design principles. For example, externally toothed, unlined steel discs can be used alternately with internally toothed discs coated on both sides. The coating can have a thickness comparable to paper and be processed using paper-like techniques, in which case it is also referred to as a paper coating. The coating can be plastic-based and / or contain additive particles similar to those used in dry clutches. Alternatively, single-sided coated inner discs can be used, in which case, for example, a coating can also be applied to the outer discs.

[0068] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of exemplary embodiments. Where the term "can" is used in this application, it refers to both the technical possibility and the actual technical implementation. Where the term "approximately" is used in this application, it means that the exact value is also disclosed.

[0069] The figures are not drawn to scale; in particular, the aspect ratios of the elements can be chosen differently.

[0070] Exemplary embodiments of the invention are explained below with reference to the accompanying drawings. These show: Fig. 1 an electromagnetic wheel hub drive as an external rotor with perimeter disc brake (section view, perspective), Fig. 2 a cross-sectional view of the wheel hub drive, Fig. 3 a detailed view of the wheel hub drive, Fig. 4 a wheel hub external rotor motor, and Fig. 5 a configuration of an electric motor with, for example, twelve windings.

[0071] The Fig. Figure 1 shows an electromagnetic wheel hub drive 8 with an external rotor electric motor 10 and a perimeter disc brake 16 in a perspective sectional view. The electric motor 10 includes an annular stator carrier 12 and an annular rotor carrier 14, the stator carrier 12 having a smaller outer diameter compared to the inner diameter of the rotor carrier 14. The stator carrier 12 and rotor carrier 14 are arranged coaxially or concentrically to each other on a rotational axis A. A radial direction R is indicated in the Fig. 1 also shown.

[0072] The stator support 12 carries stator windings 62, see Fig. 2, and the rotor carrier 14 carries magnets, in particular permanent magnets, which are not shown.

[0073] A multi-disc brake 16 is arranged on the stator carrier 12 and on the rotor carrier 14, which serves to brake the electric motor 10. The construction of the multi-disc brake 16 is described below, in particular with reference to the Fig. 3, explained in more detail.

[0074] A rim 18 is attached to the rotor carrier 14, for example by screws. The rim 18 is, for example, a standard 15-inch (1 inch equals 2.54 centimeters), 16-inch, 17-inch, or other rim. However, special rims adapted to the electric motor 10 can also be used.

[0075] A tire 20 is mounted on the rim 18, e.g. an air-filled tire or a solid tire.

[0076] An example of electronic control of the electric motor 10 is not shown, but will be described below using the Fig. 5 explained in more detail.

[0077] The stator carrier 12 widens on one side to form a receiving part 21, which accommodates the inner plates of the multi-plate brake 16 as well as an actuating element of the multi-plate brake 16, see ball ramp actuator 52. The receiving part 21 is connected to a side wall 22, which in the exemplary embodiment is designed in the shape of a frustoconical shell, but can also have a different shape. The side wall 22 can also be omitted if necessary. The bearing is located within the frustoconical shell but outside the housing 66, see [reference missing]. Fig. 2. Wheel carriers not shown are arranged, e.g. a control arm.

[0078] In the operating position of the wheel hub drive 8, the tire 20 rests with part of its circumferential surface on a road surface or other substrate. If the wheel hub drive 8 is mounted on the right side of the vehicle, the truncated conical surface of the side wall 22 is located on the left side of the wheel hub drive 8. Conversely, if the wheel hub drive 8 is mounted on the left side of the vehicle, the truncated conical surface of the side wall 22 is located on the right side of the wheel hub drive 8, i.e., facing the vehicle.

[0079] The side wall 22 borders radially on the inside an inner ring 24, which is mounted concentrically to axis A and has a diameter matched to a bearing 34 for supporting a rotor journal or rotor inner part 32. The diameter of the inner ring 24 is considerably smaller than the diameter of the stator carrier 12, e.g., less than half the diameter of the stator carrier 12. The bearing 34 is, for example, a double bearing, such as a helical double ball bearing. Alternatively, a simple ball bearing or roller bearing is used.

[0080] For example, a flat, disc-shaped side wall 26 lies opposite the side wall 22 and borders radially on the outside of the stator carrier 12. Radially on the inside, the side wall 26 borders the inner ring 24. The side wall 26 can also have a different shape, e.g., corrugated along the radial direction R, for example, to increase stability.

[0081] The stator carrier 12, the receiving part 21 of the stator carrier 12, the side wall 22, the inner ring 24 and the side wall 26 form an annular housing 66 in which, for example, the control electronics of the electric motor 10 are arranged. Furthermore, oil pumps and / or oil filters and / or oil lines and, if applicable, other components can be arranged in the preferably closed housing 66.

[0082] A rotor wall 30 connects the rotor carrier 14 to the rotor journal or rotor inner part 32. The rotor wall 30 is, for example, designed as a flat disk. The rotor wall 30 is arranged parallel to and at a distance from the side wall 26. In the exemplary embodiment, the rotor wall 30 is also arranged parallel to and at a distance from a side wall 40 of the rim 18. The rim center 42 of the rim 18 is arranged parallel to the center of the rotor wall without a distance to it.

[0083] In the Fig. Figure 1 also shows an outer seal 44, which is mounted on an annular projection 46 formed on the outside of the receiving part 21. The outer seal 44 is held in place at the bottom by means of the Fig. 3 explained in more detail.

[0084] An inner seal 48 is arranged on a projection of the receiving part 21 in a U-shaped recess 50. In the exemplary embodiment, the inner seal 48 lies precisely at the air gap of the electric motor 10, see air gap 64 in the Fig. 2.

[0085] Between the outer seal 44 and the inner seal 44 is the lamellar brake 18 or its lamellae in a chamber 88, see Fig. 3, which is filled with a suitable oil.

[0086] The ball ramp actuator 52, for example, is constructed as explained in the introduction, i.e., two rings that are rotated relative to each other, with at least one ring having a slope or ramp on which balls or other bodies can roll.

[0087] The Fig. Figure 2 shows a cross-sectional view of the wheel hub drive 8. The housing 66 is particularly visible, with a stator cooling jacket 60 attached to the stator carrier 12 around its circumference. For example, a water jacket cooling system with a counterflow principle or another cooling method is used. The cooling serves to cool the stator lamination stacks and windings 62, which extend to the air gap 64 of the electric motor 10. The cooling jacket 60, as well as the stator lamination stacks and windings 62, are located in the Fig. 2 is only shown symbolically, i.e. the construction details can also be chosen differently than shown.

[0088] The air gap 64 between the rotor magnets and the stator laminations, for example, has a gap width between 0.5 millimeters and 5 millimeters. The width of the air gap is, for example, between 4 centimeters and 15 centimeters. The length of the air gap corresponds to the circumference along the stator laminations.

[0089] In the Fig. Figure 2 also shows a distance A1 and a distance A2, which lie at radii R1 and R2, respectively, between the side walls 22 and 26. The radius R2 is smaller than the radius R1. The distance A2 is smaller than the distance A1, for example, by at least half the value of the distance A1. The values ​​of the distances A1 and A2 are determined by the shape of the side wall 22, which widens with increasing radial distance from axis A. The distance A1 or A2 is measured, for example, from the inner surface of the side wall 26 to the inner surface of the side wall 22. Alternatively, other reference points can be chosen, such as a center line of the side wall 26 or 22, in which case the ratios between the distances A1 and A2 given above can also apply.

[0090] An inner diameter D1 of the rotor carrier 14 is larger than an outer diameter D2 of the stator carrier 12, e.g. by at least 10 percent of the inner diameter D1. An inner diameter D3 of the stator carrier 12 is smaller than the outer diameter D2 of the stator carrier 12, e.g. by a maximum of 10 percent of the outer diameter D2.

[0091] The Fig. Figure 3 shows a detailed view of the wheel hub drive 8, in particular a detailed view of the receiving part 21, on which linear guides 95 are formed, e.g. trapezoidal projections and trapezoidal recesses or grooves that run in the axial direction A, i.e. parallel to the axis A. Alternatively, rectangular or square shapes or a combination of the aforementioned shapes are used.

[0092] The linear guides 95 are matched to the internal teeth of the inner plates 70 to 76 of the multi-plate brake 16. The inner plates 70 to 76 are designed as lamellar rings, e.g., made of steel. The inner plates 70 to 76 are axially movable on the linear guides 95 and can be compressed by the actuating element of the multi-plate brake 16, which is described in more detail below, in particular together with the outer plates 80 to 86 of the multi-plate brake 16, which are also described in more detail below.

[0093] The inner plates 70 to 76 are coated with a lining (not shown), in particular on both sides or one side; for another brake, see also lining 370a in Fig. 4. The statements mentioned in the introduction apply to the lining and oil of the lamellar brake 16.

[0094] Opposite the free ends of the inner lamellae 70 to 86, linear guides 96 are formed, which can, for example, also consist of trapezoidal projections and trapezoidal recesses, preferably extending in the axial direction a. Alternatively, rectangular or square shapes, or a combination of these shapes, are used. The linear guides 96 are aligned with external teeth of the outer lamellae 80 to 86 of the multi-plate brake 16. The outer lamellae 80 to 86 are also designed as lamellar rings, for example, made of steel. The outer lamellae 80 to 86 are mounted axially movable on the linear guides 96 and can be compressed by the actuating element of the multi-plate brake 16, which is described in more detail below, in particular indirectly via the inner lamellae 70 to 76 of the multi-plate brake 16.

[0095] In this embodiment, the outer slats 80 to 86 are not coated. Alternatively, both the inner and outer slats can be coated, for example, on the outward (top) side or surface, or on the inward (bottom) side or surface. Alternatively, only the outer slats can be coated.

[0096] Although in the Fig. Where four pairs of lamellae are shown, a different number of pairs can also be used, in particular a number between two and twenty.

[0097] An annular oil chamber 88 is formed between the linear guides 95 and 96. Due to the inner plates 70 to 76 arranged in the oil chamber 88, alternating with the outer plates 80 to 84, the oil flows in a meandering pattern between the spaced plates in the oil chamber 16 when the multi-plate brake 16 is not actuated. When the multi-plate brake 16 is actuated, the gaps between the plates 70 to 76 and 80 to 86 are reduced until adjacent plates 70 to 76 and 80 to 86 touch. The oil is forced out of the meanders and can flow, for example, along the guides 95, 96 into the side area of ​​the oil chamber 88, from where it flows back again when the lamellar brake 16 is relaxed or released, especially along the meanders that then re-form.

[0098] The oil chamber 88 can be connected to an oil filter and / or an oil pump via oil lines or oil channels (not shown) in the receiving part 21. The oil can, for example, be supplied to a cooling device and / or used to heat the vehicle interior.

[0099] In the exemplary embodiment, the actuating element of the multi-plate brake 16 is formed by a ball ramp actuator 52, which contains two grooved rings 90, 92 arranged in the receiving part 21 near the inner plate 76 and the outer plate 86. Alternatively, the ball ramp actuator 52 can also be located adjacent to an outer plate. The rings 90, 92 have a mean diameter that corresponds approximately to the mean diameter of the inner plates 70 to 76 or, for example, deviates from the mean diameter of the inner plates 70 to 76 by a maximum of 5 percent or a maximum of 10 percent. To determine the mean diameter of the inner plates 70 to 76, reference is made, for example, to a smallest inner diameter of the toothing and to the outer diameter of the respective inner plate 70 to 76.

[0100] Balls, see e.g. ball 54, or other rolling elements are arranged between the grooved rings 90 and 92. In the unactuated state, a gap 94 may already exist between rings 90 and 92. Alternatively, the gap 94 only arises when the multi-disc brake 16 is actuated by the rotation of ring 92 relative to ring 90. Alternatively, both rings 90 and 92 may be rotated when the multi-disc brake 16 is actuated, or only ring 90. The rotation occurs in the circumferential direction of rings 90 and 92, respectively.

[0101] Ring 90 and / or ring 92 has a groove with a pitch to accommodate the balls, see e.g. ball 54, or the other rolling elements. This pitch increases the distance between rings 90 and 92 when at least one ring 90 or 92 is rotated. The ball ramp actuator 52 can be connected to the oil chamber 88 for lubrication. Alternatively, separate lubrication can be used for the ball ramp actuator 52.

[0102] The rotation of the rings 90, 92 relative to each other can be carried out by a known device, e.g. using a hydraulic or pneumatic piston.

[0103] A return element (not shown) facilitates the release of the multi-disc brake 16, e.g., suitable spring washers between the discs 70 to 76 or 80 to 86. Alternatively, no separate return elements are used for resetting the multi-disc brake 16.

[0104] A screw 97 can be used to fasten a stop ring 99 (not shown) for the inner lamellae 70 to 76. Alternatively, a snap ring can be used, i.e., the screw 97 is not used.

[0105] A screw 98 can be used to fasten a stop ring (not shown) for the outer lamellae 80 to 86 to the rotor carrier 14, as well as a chamber wall 87 to the rotor carrier 14. Alternatively, a snap ring can be used as a stop ring for the outer lamellae 80 to 86. Alternatively, a stop ring can be used either on the inside or on the outside. The chamber wall 87 is drawn inwards as far as possible to reduce the diameter of the outer seal 44 and thereby minimize friction losses. Alternatively, the chamber wall 87 can be shortened, allowing the outer seal 44 to be positioned further outwards, e.g., on the same radius as the inner seal 48.

[0106] For example, the width B1 of the receiving part 21 is more than twice or more than three times as large as the width B2 of the stator carrier 12.

[0107] The outer seal 44 is mounted on the projection 46. In the exemplary embodiment, a U-shaped shaft seal ring is used as the outer seal 44, which contains the following parts: - a ring-shaped bearing part that rests against a side surface of the projection 46 and contains, for example, a metal insert or is made of metal, - a disc-shaped central part arranged transversely, in particular at an angle of 90 degrees, to the bearing part, which also contains metal or is made of metal, and - a ring-shaped free part arranged transversely to the central part with a sealing lip, e.g. made of a plastic material, possibly supported by a metal ring, in particular a compression spring ring.

[0108] The bearing portion and the free portion extend in the same direction away from the central portion, which can also be referred to as the base. In the exemplary embodiment, the base of the outer seal 44 is located on the outside of an opening in which the outer seal 44 is mounted. Thus, the sealing lip exerts a radially outward pressure on the side wall 87, which rotates during operation of the electric motor 10. Alternatively, a V-shaped or an L-shaped outer seal 44 can also be used, whereby reference is made to the introduction regarding the choice of material and temperature resistance for all the aforementioned seal types.

[0109] The inner seal 48 is mounted in the, for example, annular recess 50. In the exemplary embodiment, a U-shaped shaft seal ring is used as the inner seal 48, which contains the following parts: - a ring-shaped bearing part that rests on the bottom of the recess 50 and contains, for example, a metal insert or is made of metal, - a disc-shaped central part arranged transversely, in particular at an angle of 90 degrees, to the bearing part, which for example also contains metal or consists of metal and which rests against a side surface of the recess 50, and - a ring-shaped, free part arranged transversely to the middle part with a sealing lip, e.g. made of a plastic material.

[0110] The bearing portion and the free portion extend in the same direction away from the central portion, which can also be referred to as the base. In the exemplary embodiment, the base of the inner seal 48 is located on the side wall of the recess 50 that is closer to the air gap 64. Thus, the sealing lip exerts a radially outward pressure on the rotor carrier 14, which rotates during operation of the electric motor 10. Alternatively, a V-shaped or an L-shaped inner seal 48 can also be used; reference is made to the introduction regarding the material selection and temperature resistance of all the aforementioned seal types.

[0111] One or both seals 44, 48 can also be mounted on the rotor carrier 14, e.g. with compression spring rings in the seals. The position of the base remains unchanged, so that the sealing lip of seal 44 can then rest against the receiving part 21 and vice versa.

[0112] In another embodiment, the ball ramp actuator 52 or 54 can be arranged centrally in the disc pack of the multi-disc brake 16 or another multi-disc brake. Instead of a ball ramp actuator, a hydraulic double piston or several hydraulically actuated pistons can also be used here. In both cases, the inner seal 48 can then be arranged further radially inward than in the Fig. Figure 3 shows, in particular on the same radius as the outer seal 44. The air gap 64 can remain in the same position as shown in the Fig. 3 shown, however there is a radially oriented gap between the inner seal and the air gap 64.

[0113] In another variant, construction is possible without the inner seal 48. In this case, the oil from the oil chamber 88 also penetrates the air gap 64 and the bearing 34, see [reference]. Fig. 1 and Fig. 2.

[0114] The assembly of the electric motor 10 is carried out as follows: - the cooling system, the windings and the laminated cores are mounted on the stator carrier 12, - then the seal 48, the ring 90, the balls 54, possibly with a so-called cage, and the ring 92 are inserted, parts 90 to 92 possibly as a prefabricated component, - then the rotor carrier 14 is mounted, - then the outer slats 80 to 86 and the inner slats 70 to 76 are inserted alternately, - the stop ring for the inner slats 70 to 76 is fastened with the help of screw 97 and with other screws or in another way, in particular for the outer slat 80, - the stop ring for the outer slats 80 to 86, in particular for the outermost slat 80, is placed on, - the wall 87 and the stop ring for the outer louvers are fastened with screw 98 and with other screws, - the seal 44 is inserted, and - immediately or later, oil chamber 88 will be filled with oil.

[0115] If the seal 48 runs in a groove, the rotor 14 can be split at this point, i.e. at the seal.

[0116] In this way, the lamellar brake 16 can also be serviced without disassembling the rim 18 by performing the steps indicated above in reverse order after draining the oil.

[0117] The Fig. Figure 4 shows a wheel hub external rotor motor 100a which is part of a wheel hub drive 102a. A rotor 120a rotates about the axis of rotation A. The electric motor 100a includes a stator 140a arranged inside the rotor 120a.

[0118] The stator 140a contains a cylindrical ring, which is closed on one side (here, the right) by, for example, a circular side wall, which may be reinforced by radial ribs, so that a stator interior is formed inside the ring. The side wall is rigidly connected on the side facing away from the stator interior to a fixing 160a, which is, for example, mounted on a vehicle frame, particularly using a transverse control arm. In this example, the side wall of the stator 140a is on the right side. A rotor shaft is not present but can be provided.

[0119] The rotor 120a also contains a cylindrical ring, which is rotatably mounted about the axis of rotation A. The cylindrical ring of the stator 140a and the cylindrical ring of the rotor 120a are mounted coaxially to each other, with the ring of the rotor 120a being located outside the ring of the stator 140a. Permanent magnets M2 are arranged on the inside of the ring of the rotor 120a, which are moved or driven by a rotating magnetic field generated by the coils of the stator 140a.

[0120] One side of the rotor 120a ring is closed by a circular disk. On the free side of the rotor 120a ring is located – to the right in Fig. 4 - a rotor plate 150a, which is designed, for example, as a disc ring or circular ring and which covers an interior space of the motor 100a.

[0121] The ring of the stator 140a has a smaller height in the axial direction than the ring of the rotor 120a, so that it can be arranged inside the motor 100a.

[0122] The rotor 120a is mounted on the stator 140a by means of a bearing 180a, e.g. a deep groove ball bearing which contains, for example, preloaded cones. Thus, the rotor 120a can rotate around the axis of rotation A and also around the stator 140a.

[0123] The rotor 120a and the stator 140a are in the Fig. Figure 4 shows a highly foreshortened view in the radial direction R. The motor 100a is located completely inside a rim 200a. The rim 200a is, for example, a 15, 16, 17, 18, or 19-inch rim. Alternatively, the rim 200a can have a different nominal size. The rim 200a has a [missing information] on its [missing information] in the Fig. 4. On the left side, a rim carrier 210a, which is also designed, for example, as a circular disc. Alternatively or additionally, the rim carrier 210a can contain ribs.

[0124] A tire 220a is mounted on the rim 200a, which contains, for example, a rubber compound and, for example, steel inserts.

[0125] A screw connection 240a and other screw connections not shown serve to fasten the rotor plate 150a to the rotor 120a. A seal 260a can be provided between the rotor plate 150a and the rotor 120a along the circumferential direction, e.g. a statically sealing O-ring or a statically sealing flat gasket.

[0126] A screw connection 320a serves to fasten the rim 200a, or more precisely the rim carrier 210a, to the rotor 120a. The rotor 120a has an outwardly facing side wall to which the screw connection 320a is attached. Further screw connections, not shown, serve to fasten the rim 200a to the rotor side wall. Optionally, a rotor shaft may also be formed on the rotor 120a to fasten the rim 200a; see [reference]. Fig. 1, Fig. 2 to Fig. 3.

[0127] Alternatively, a different method of attaching the tire 220a to the motor 100a can be chosen, e.g. directly to the rotor 120a, i.e. without using an additional rim or using an “outer rim”, i.e. e.g. without rim carrier 210a.

[0128] A multi-disc brake 360a is arranged on the rotor 360a and the stator 140a. More precisely, inner discs 70a with internal teeth are arranged on linear guides on the stator 140a, and outer discs with external teeth are arranged on linear guides on the rotor. In the exemplary embodiment, there are two pairs of discs and an additional outer disc 80a. Again, the inner discs 70a are coated on both sides with a lining, see, for example, lining 370a on the left side of the right inner disc 70a. However, a different number of pairs of discs 70a, 80a can also be used.

[0129] An actuating element 340a (actuator) of the multi-disc brake 360a is arranged on the stator 140a. Seals of the multi-disc brake 360a are located in the Fig. 4 not shown. However, the same or similar sealing concepts as above can be used based on the Fig. 1, Fig. 2 to Fig. 3 explained, can be used. The lamellar brake 360a can also be positioned closer to the rotor side wall 120a, which is also suitable for the Fig. 1, Fig. 2 to Fig. 3 applies, i.e. between magnets, e.g. M2, or stator windings and the rotor side wall 120a.

[0130] A U-ring, several U-rings, or other sealing elements, such as a V-ring, can be used to seal the 360a disc brake. One or more L-shaped sealing elements can also be used to seal the 360a disc brake or its aforementioned variations. Combinations of these sealing types are also possible in all embodiments.

[0131] The 100a motor can also be used with a stator with a conical side wall. The 360a multi-disc brake is mounted in the same way as the 16-disc brake.

[0132] The Fig. Figure 5 shows a configuration of an electric motor 400 with, for example, twelve windings W1 to W12. Alternatively, a different number of windings can be used.

[0133] The electric motor 400 is an external rotor motor and comprises a stator 402 and a rotor 404. On the stator 402, the windings W1 to W12 are arranged around laminated cores. A plurality of magnets are arranged on the rotor, with one magnet M10 located in the Fig. Figure 5 is shown. Alternatively, electrically conductive rods or windings can be used on the rotor 404, into which currents are induced to generate the magnetic fields.

[0134] The 400 electric motor also contains a perimeter disc brake, which, however, is located in the Fig. Figure 4 is not shown for clarity. The electric motor 400 can be used like the ones in the Fig. 1, Fig. 2, Fig. 3 to Fig. The 4 electric motors shown are 10 and 100a.

[0135] The switching bridges assigned to windings W7 to W12 are controlled in the same way as the switching bridges assigned to windings W1 to W6, but with the opposite winding direction for windings W7 to W12 compared to windings W1 to W6. With the same winding direction / connection, the switching bridges assigned to windings W7 to W12 are controlled in the opposite way to the switching bridges assigned to windings W1 to W6, where "in the opposite way" means, for example, that the control signals for the upper bridge transistor / switch and the control signals for the lower bridge transistor / switch are reversed.

[0136] The electric motor 400 corresponds, for example, to the electric motor 10, see Fig. 1, Fig. 2 to Fig. 3, or the 100a wheel hub motor. In the Fig. In the configuration shown, six phases can be used to control twelve half-bridges. Alternatively, only six half-bridges can be used, as explained in more detail below.

[0137] Windings W1 to W12 can be connected together at a star point. The following circuit applies to the other ends of windings W1 to W6: - the winding W1 is connected to the center node of a first half-bridge, the center node being connected to the working sections of both switching elements of the half-bridge, which also applies to the other half-bridges. - the winding W2 is connected to the center node of a second half-bridge, - the winding W3 is connected to the central node of a third half-bridge, - the winding W4 is connected to the central node of a fourth half-bridge, - the winding W5 is connected to the center node of a fifth half-bridge, and - the winding W6 is connected to the center node of a sixth half-bridge.

[0138] The lower switching element of each of the six half-bridges is connected to a common negative lead. The upper switching element of each of the six half-bridges is connected to a common positive lead.

[0139] Each of the six half-bridges is controlled by a pair of control signal lines, with one control line leading to a control terminal of the upper switching element, e.g., gate, and the other control line leading to a control terminal of the lower switching element of the respective half-bridge.

[0140] In the configuration shown, the six phases are arranged with increasing phase shifts between adjacent phases, i.e., 0 degrees, 60, 120, 180, 240, and 300 degrees. Due to the use of six phases to control twelve windings W1 to W12, a torque characteristic curve results that is dependent on the rotational speed. The efficiency is also dependent on the rotational speed.

[0141] The half-bridges belonging to windings W6 to W12 are controlled like the half-bridges of windings W1 to W6, based on the six phases. However, it is also possible to operate with only six half-bridges of higher power if, for example, the first half-bridge controls the current through windings W1 and W7, the second half-bridge controls the current through windings W2 and W8, and so on.

[0142] For the Fig.5 applies, Q = 12, p = 1 and m = 6, where Q is the number of slots used, p is the number of pole pairs and m is the number of electrical phases. Furthermore: q=Q / (2p*m)=1, where q is the number of slots used per winding. Other values ​​for Q, p, and m are also possible. Other winding schemes can also be used.

Claims

[1] Electric machine (10, 100a, 400), comprising: a ring-shaped stator carrier (12), a ring-shaped rotor carrier (14) having an inner diameter (D1) that is larger than an outer diameter (D2) of the stator carrier (12) and which is arranged concentrically or coaxially with the stator carrier (12) on an axis of rotation (A), a wet-running multi-disc brake (16) arranged on the stator carrier (12) and on the rotor carrier (14), which is arranged in an oil-filled installation space (88), a sealing element (44) that closes off the oil-filled installation space (88) to an outside of the electric machine (10, 100a, 400), wherein a first number of brake plates (70 to 76) of the multi-plate brake (16) is arranged on a receiving part (21) of the stator carrier (12), and wherein the receiving part (21) is formed integrally with the stator carrier (12). [2] Electric machine (10, 100a, 400) according to claim 1, wherein the receiving part (21) is arranged parallel to the axis of rotation (A) next to the stator carrier (12). [3] Electric machine (10, 100a, 400) according to claim 1 or 2, wherein the receiving part (21) has a larger radial dimension (B1) than the radial dimension (B2) of the stator carrier (B2, 12). [4] Electric machine (10, 100a, 400) according to one of the preceding claims, wherein at least one support element (22) is arranged between the receiving part (21) and an inner ring (24) of the electric machine (10, 100a, 400). [5] Electric machine (10, 100a, 400) according to claim 4, wherein the at least one support element (22) is a first support element (22), and wherein at least one second support element (26) is arranged between the stator carrier (12) and the inner ring (24), wherein a first distance (A1) in axial direction (A) between the at least one first support element (22) and the at least one second support element (26) at a first radius (R1) is at least twice as large as a second distance (A2) between these parts (22, 26) at a second radius (R2) which is further inwards than the first radius (R1). [6] Electric machine (10, 100a, 400) according to claim 4 or 5, wherein at least one bearing (34) for rotatable mounting of the rotor carrier (14) on the stator carrier (12) is arranged inside the inner ring (24). [7] Electric machine (10, 100a, 400) according to one of the preceding claims, wherein the oil-filled installation space (88) is sealed towards an air gap (64) located between the stator support (12) and the rotor support (14) by a further seal (48), wherein the further seal (48) has a larger diameter than the sealing element (44) that seals towards the outside. [8] Electric machine (10, 100a, 400) according to one of the preceding claims, wherein a vehicle wheel is driven directly by the electric machine (10, 100a, 400). [9] Electric machine (10, 100a, 400) according to one of the preceding claims, wherein an actuating element (52) of the multi-plate brake (16) includes a ball ramp actuator (52, 54) or at least one hydraulic piston that acts directly on the plates (70 to 76), and wherein the actuating element (52, 54; 340a) is arranged on the stator carrier (12). [10] Electric machine (10, 100a, 400) according to one of the preceding claims, with a rim (18) which is connected to the rotor carrier (14) and which includes a side wall (40) or side struts which lead to a rim disc. [11] Electric machine (10, 100a, 400) according to one of the preceding claims, wherein the rated power of the electric machine (10, 100a, 400) is less than 150 kilowatts or wherein the rated power of the electric machine (10, 100a, 400) is greater than 150 kilowatts. [12] Electric machine (10, 100a, 400) according to one of the preceding claims, wherein the electric machine (10, 100a, 400) is used for the wheel hub drive of a passenger transport vehicle. [13] Electric machine (10, 100a, 400) according to one of the preceding claims, wherein the stator support (12) has an inner diameter (D3) in the range of 30 to 50 centimeters and wherein the outer diameter (D2) of the stator support (12) is at most 6 centimeters larger than the inner diameter (D3). [14] Method for braking an electric machine (10, 100a, 400) according to one of the preceding claims, comprising: Arranging a lamellar brake (16, 360a) on a stator support (12) and on a rotor support (14) of an electric machine (10, 100a, 400), Arranging an actuating element (52, 54; 340a) of the multi-disc brake (16) on at least one disc (70 - 76) of the multi-disc brake (16, 360a), Sealing the multi-disc brake (13, 360a) with a sealing element (44) that closes off a construction space (88) in which the multi-disc brake (13, 360a) is arranged to an outside of the electric machine (10, 100a, 400), Filling the multi-disc brake (13, 360a) with a fluid, Actuating the multi-disc brake (13, 360a) to brake the electric motor (10, 100a, 400).

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