Electric drive unit with an axial flux machine

Abstract

The invention relates to an electric drive device (1) with an axial flux machine (2), wherein the axial flux machine (2) comprises: - a first rotor disk (R1) on which first magnetic elements (M1) are arranged, - a second rotor disk (R2) on which second magnetic elements (M2) are arranged, and - a stator (3) arranged between the rotor disks (R1, R2). According to the invention, the electric drive device (1) is characterized by an output shaft (4) which is non-rotatably connected to the second rotor disk (R2), and an adjusting device (7) by means of which the first rotor disk (R1) can be rotated relative to the second rotor disk (R2), wherein the adjusting device (7) comprises: - a rotor shaft (5) which is rigidly connected to the first rotor disk (R1) and is axially fixed, - a sleeve (6) which is arranged on the output shaft (4) and in the rotor shaft (5), is rotationally fixed to the output shaft (4), is axially displaceable on the output shaft (4) and has a helical toothing (9) on an outer circumference of the sleeve which engages in a corresponding helical toothing (11)' on an inner circumference of the rotor shaft (5), and - an actuator device (12) designed to axially displace the sleeve (6) on the output shaft (4).

Description

[0001] The invention relates to an electric drive device with an axial flux machine according to the features of the preamble of claim 1.

[0002] An axial flux machine with a field weakening function is known from the prior art, as described in EP 4 037 166 A1. The axial flux machine has a rotor comprising a first and a second rotor disk, a displacement element, a first and a second pair of mechanical fitting elements which, by rotating the first and second rotor disks, enable an axial displacement of the first and second rotor disks relative to the displacement element, wherein an equal rotation of the first and second rotor disks leads to an equal but opposite axial displacement of the first and second rotor disks, and a coupling element for mechanically coupling the first and second rotor disks, thereby blocking rotation of the first rotor disk relative to the second rotor disk and simultaneously enabling axial displacement.

[0003] DE 14 88 273 A1 discloses an alternating current generator in which the parts generating a magnetic field are opposite one another, wherein means are provided for displacing the parts generating the magnetic field relative to one another in order to exert a control effect.

[0004] EP 4 037 166 A1 describes an axial flux machine which comprises an actuator with a plurality of axially displaceable parts and is designed to push apart a first and a second rotor disk by an axial movement of the one or more axially displaceable parts.

[0005] From DE 101 20 742 A1 a wheel drive with an electric motor arranged between a wheel axle and a rim flange of a wheel rim is known.

[0006] The invention is based on the object of providing an electric drive device with an axial flux machine that is improved compared to the prior art.

[0007] The object is achieved according to the invention by an electric drive device with an axial flux machine having the features of claim 1.

[0008] Advantageous embodiments of the invention are the subject of the subclaims.

[0009] An electric drive device comprises an axial flux machine. The axial flux machine comprises the following: - a first rotor disc on which first magnetic elements are arranged, - a second rotor disc on which second magnetic elements are arranged, and - a stator arranged between the rotor discs.

[0010] According to the invention, the electric drive device, in particular its axial flux machine, has an output shaft that is rotationally fixedly connected to the second rotor disk. The output shaft is arranged in a fixed manner in the axial direction, i.e., it is particularly rotatable but not axially displaceable. Furthermore, an adjusting device is provided, by means of which the first rotor disk can be rotated relative to the second rotor disk. This adjusting device has the following: - a rotor shaft which is fixedly connected to the first rotor disc, ie in particular in a rotationally fixed manner and also in the axial direction, and which is in particular axially fixed, ie not movable in the axial direction, - a sleeve which is arranged on the output shaft and in the rotor shaft, is connected to the output shaft in a rotationally fixed manner, is arranged axially displaceably on the output shaft and has a helical toothing on an outer circumference of the sleeve, which engages in a corresponding helical toothing on an inner circumference of the rotor shaft, and - an actuator device which is designed to axially displace the sleeve on the output shaft and in particular relative to the first rotor disk and its rotor shaft, whereby the rotation of the first rotor disk relative to the second rotor disk can be effected, in particular by the first rotor disk being rotated around the output shaft by means of the intermeshing helical gears of the sleeve and rotor shaft and the axial displacement of the sleeve on the output shaft and thereby being rotated relative to the second rotor disk which is connected in a rotationally fixed manner to the output shaft.

[0011] In order to enable this rotation of the first rotor disk by means of the corresponding helical gears, the first rotor disk and in particular its rotor shaft are fixed in the axial direction, in particular fixed relative to the output shaft, ie the first rotor disk and its rotor shaft do not move together with the sleeve in the axial direction, but are fixed in the axial direction, and the sleeve is axially displaceable relative to the first rotor disk and its rotor shaft or is axially displaced by means of the actuator device relative to the first rotor disk and its rotor shaft.

[0012] To enable this, the sleeve, as described, is arranged on the output shaft and in the rotor shaft. This means that it is arranged on an outer circumference of the output shaft and has helical gearing on its outer circumference, which engages with the helical gearing on the inner circumference of the rotor shaft. The output shaft, the sleeve, and the rotor shaft are thus arranged coaxially. The sleeve is arranged radially between the output shaft and the rotor shaft. The sleeve is thus hollow, and the rotor shaft is designed as a hollow shaft. In one possible embodiment, the output shaft is also designed as a hollow shaft.

[0013] Helical gearing means that the teeth of the two helical gears are each aligned obliquely to the axial direction of the sleeve and rotor shaft.

[0014] To achieve a simultaneously non-rotatable and axially displaceable connection between the sleeve and the output shaft, the output shaft is provided with a straight toothing on its outer circumference, which engages with a corresponding straight toothing on the inner circumference of the sleeve. Straight toothing means that the teeth of these two straight toothings are each aligned in the axial direction of the output shaft, so that the sleeve is axially displaceable on the output shaft and is non-rotatably connected to the output shaft.

[0015] The adjustment device enables a rotor phase adjustment and thus a magnetic field change, i.e., depending on the rotational position of the first rotor disk relative to the second rotor disk, a field weakening or field strengthening.

[0016] The magnetic elements of the first rotor disk and / or the magnetic elements of the second rotor disk are each designed as a permanent magnet.

[0017] In one possible embodiment, the actuator device has a hydraulic device acting on an end face of the sleeve in the axial direction, which is designed to displace the sleeve axially in one direction.

[0018] In one possible embodiment, the hydraulic device is arranged on a housing of the axial flow machine and is connected to the sleeve via a rolling bearing or plain bearing.

[0019] The actuator device has in particular a return device acting on the other end face of the sleeve in the axial direction, which is designed to displace the sleeve axially in the opposite direction.

[0020] In one possible embodiment, the return device is designed as a spring unit or as a further hydraulic device.

[0021] Advantageously, the actuator device is located radially centrally or in a central region of the axial flux machine, particularly in the area of ​​the output shaft and the first rotor. The sleeve and the rotor shaft are also located in the center of the first rotor. This achieves a compact design and prevents imbalance.

[0022] In particular, it is provided that a load is coupled to the output shaft. The load is, in particular, an element to be driven by the axial flux machine, which is coupled to the output shaft, for example, directly or via a gearbox. If a gearbox is provided, then, in particular, a gearbox input shaft is coupled to the output shaft.

[0023] The electric drive system is designed, for example, as a wheel hub drive of a vehicle or for a vehicle. It requires less installation space than previously known wheel hub drives with axial flux machines. Due to the rotor phase shift enabled, for example, by up to 180°, a separation unit is no longer required, which, when using a conventional axial flux machine, is arranged between an output of the axial flux machine and a vehicle wheel, before or after the transmission. This saves installation space for this separation unit, and the axial flux machine can be arranged closer to the wheel.

[0024] For example, a wheel hub and / or a wheel of the vehicle is / are coupled to the output shaft.

[0025] In one possible embodiment, the electric drive device, as already mentioned, comprises a transmission, with the transmission input shaft of the transmission being coupled to the output shaft. If the embodiment of the electric drive device designed as a wheel hub drive comprises such a transmission, then a transmission output shaft of the transmission is expediently coupled to the wheel hub and / or the wheel of the vehicle.

[0026] The axial flow machine of the described solution has a rotor phase adjuster, in particular a hydraulic one, in the form of the adjusting device, because the adjusting device makes it possible to adjust the rotor phases, for example between 0° and 180°.

[0027] This solves the problem of the axial flux machine's very low d-inductance and q-inductance. This leads to difficulties with field weakening due to a weak armature reaction. Furthermore, the field weakening current increases the ohmic losses of the axial flux machine and exposes the permanent magnets to a state of irreversible demagnetization.

[0028] Due to the permanent magnets, an active short circuit is absolutely necessary as a fault response at high speeds in conventional axial-flux machines in automotive applications. Power modules are therefore currently oversized to carry the short-circuit current for a certain period of time. In addition, conventional axial-flux machines integrate a disconnection unit into the drive system to protect the power module from the high active short-circuit current.

[0029] Furthermore, a high axial force is constantly present in conventional axial flux machines, even when the stator is de-energized. This constant axial force could lead to deformation of the rotor, especially the rotor disks, and to contact between the rotor, especially the rotor disks, and the stator.

[0030] As already mentioned, the described solution enables a rotor phase adjustment by means of the adjustment device and thus a mechanical field weakening for the axial flux machine, whereby the above-mentioned disadvantages of conventional axial flux machines can be overcome.

[0031] The described solution enables realistic mechanical field weakening without negative effects in the axial direction. This eliminates the need for a d-current, resulting in improved efficiency in the high-speed range. Higher torque is available in the high-speed range. The described solution enables a significant extension of the speed range. There is no risk of demagnetization of the permanent magnets due to field weakening. The described solution enables complete de-energization of the axial flux machine. A smaller active short-circuit current is required, allowing the use of a smaller and therefore more cost-effective power module. An additional separation unit or cooling pump is not required. The rotor phase adjustment enables the axial flux machine to exhibit no or very low axial force when stationary.

[0032] Embodiments of the invention are explained in more detail below with reference to drawings.

[0033] Showing: Fig. 1 schematically shows a perspective sectional view of an electric drive device with an axial flow machine, Fig. 2 schematically shows a further perspective sectional view of an electric drive device with an axial flow machine, Fig. 3 schematically shows a further perspective sectional view of an electric drive device with an axial flow machine, Fig. 4 schematically shows an embodiment of an actuation of an adjustment of a first rotor disk relative to a second rotor disk of the axial flow machine, Fig. 5 schematically shows a further embodiment of an actuation of an adjustment of a first rotor disk relative to a second rotor disk of the axial flow machine, Fig. 6 schematically shows a further embodiment of an actuation of an adjustment of a first rotor disk relative to a second rotor disk of the axial flow machine, Fig. 7 schematically shows a rotor phase shift due to the rotation of the rotor disks relative to each other, and Fig. 8 schematically shows an embodiment of the electric drive device as a wheel hub drive of a vehicle.

[0034] Corresponding parts are provided with the same reference numerals in all figures.

[0035] Based on the Fig. 1 to 8, an electric drive device 1 with an axial flux machine 2 and its operation are described below. Fig. 1 to 3 schematically show various perspective sectional views of the electric drive device 1, in particular the axial flow machine 2, which Fig. 4 to 6 show a section of the electric drive device 1, in particular of the axial flow machine 2 in the area of ​​an adjusting device 7 described in more detail below, wherein three different embodiments of the adjusting device 7 are shown schematically by way of example, Fig. 7 shows a rotor phase shift by means of the adjusting device 7 enabling rotation of rotor disks R1, R2 of the axial flux machine 2 relative to each other and Fig. 8 shows, by way of example and in a schematically highly simplified manner, an embodiment of the electric drive device 1 as a wheel hub drive of a vehicle.

[0036] The axial flux machine 2 comprises a first rotor disk R1, on which first magnetic elements M1, in particular permanent magnets, are arranged, a second rotor disk R2, on which second magnetic elements M2, in particular permanent magnets, are arranged, and a stator 3 arranged between the rotor disks R1, R2. The magnetic elements M1, M2, which for reasons of clarity are only shown in Fig. 7 are arranged, in particular, on an inner side of the respective rotor disk R1, R2 facing the stator 3, on the two rotor disks R1, R2 symmetrically or with a predetermined phase shift. They are, in particular, firmly connected to the respective rotor disk R1, R2. Reference symbol N indicates a north pole, and reference symbol S a south pole.

[0037] The axial flux machine 2 further comprises an output shaft 4, which in the example shown is designed as a hollow shaft and is rotatable relative to the stator 3, in particular is rotatably mounted in the stator 3. The output shaft 4 is connected in a rotationally fixed manner to the second rotor disk R2, i.e., the output shaft 4 rotates together with the second rotor disk R2.

[0038] The axial flow machine 2 further comprises an adjusting device 7, by means of which the first rotor disk R1 is rotatable relative to the second rotor disk R2, ie by means of this adjusting device 7, the first rotor disk R1 is rotatable in the direction of rotation relative to the second rotor disk R2 and thus also relative to the output shaft 4, around the output shaft 4, as in Fig. 1 is shown schematically by means of a double arrow DP1 indicating the two possible directions of rotation. The rotation can thus be counterclockwise, as can be seen from the comparison of the Fig. 1 and Fig. 2, in particular from a Fig. 1 shown rotational position into a Fig. 2 shown rotation position, and also back again, ie clockwise, ie in particular from the position shown in Fig. 2 shown rotation position back to the position shown in Fig. 1 rotation position shown.

[0039] By means of the adjustment device 7, further rotational positions are also possible, for example one or more rotational positions between the Fig. 1 shown rotation position and the one in Fig. 2 or one or more rotation positions via the Fig. 2. The adjusting device 7 enables, in particular, a continuous rotation of the first rotor disk R1 relative to the second rotor disk R2.

[0040] The adjusting device 7 comprises a rotor shaft 5, which is fixedly connected to the first rotor disk R1, ie, in particular, both rotationally fixed and axially fixed. This rotor shaft 5 and thus also the first rotor disk R1 are fixed in the axial direction, ie, axially immovable, in particular, not axially displaceable. Furthermore, the adjusting device 7 comprises a sleeve 6, which is arranged on the output shaft 4 and in the rotor shaft 5. This sleeve 6 is rotationally fixedly connected to the output shaft 4 and, as in Fig. 1, schematically represented by a second double arrow DP2, is arranged axially displaceably on the output shaft 4. It has a helical gear 9 on a sleeve outer circumference, which engages with a corresponding helical gear 11 on an inner circumference of the rotor shaft 5. The first rotor disk R1 with its rotor shaft 5 is axially stationary, i.e., it is not axially movable relative to the output shaft 4.

[0041] The adjusting device 7 also comprises an actuator device 12 designed to axially displace the sleeve 6 on the output shaft 4, thereby causing the first rotor disk R1 to rotate relative to the second rotor disk R2. This rotation thus occurs when the sleeve 6 is axially displaced by the actuator device 12 on the output shaft 4 and thus also relative to the rotor shaft 5, which is immovable in the axial direction. As a result, the rotor shaft 5 and thus the first rotor disk R1 are rotated around the output shaft 4 by means of the intermeshing helical gears 9, 11 of the sleeve 6 and the rotor shaft 5, and are thereby rotated relative to the second rotor disk R2, which is connected in a rotationally fixed manner to the output shaft 4.In order to realize the connection of the sleeve 6 to the output shaft 4 in such a way that the sleeve 6 is simultaneously connected to the output shaft 4 in a rotationally fixed manner and is arranged on the output shaft 4 so as to be displaceable in the axial direction, it is provided in the example shown that the output shaft 4 has a straight toothing 13 on its output shaft outer circumference, which engages in a corresponding straight toothing on a sleeve inner circumference of the sleeve 6.

[0042] The Fig. 4 to 6 show, by way of example, various embodiments of the actuator device 12 of this adjusting device 7 using a respective section in the area of ​​the adjusting device 7.

[0043] In the example according to Fig. 4, the actuator device 12 has a hydraulic device 14 acting on an end face of the sleeve 6 in the axial direction, which is designed to displace the sleeve 6 axially in one direction, in Fig. 4 to the right, and furthermore, the actuator device 12 has a return device 15 acting on the other end face of the sleeve 6 in the axial direction, which is designed to displace the sleeve 6 axially in the opposite direction, in Fig. 4 thus to the left. This reset device 15 is in the embodiment according to Fig. 4 designed as a spring unit.

[0044] The hydraulic device 14 has, in particular, a hydraulic chamber that can be filled with hydraulic fluid. This hydraulic chamber is shown in the embodiment according to Fig. 4 is formed by an outer wall of the output shaft 4 and a cylinder wall 16 arranged or formed thereon. The cylinder wall 16 has a bottom oriented radially toward the output shaft 4 and, at its edge spaced from the output shaft 4, a side wall oriented axially toward the output shaft 4.

[0045] The hydraulic chamber is thus defined by the outer wall of the output shaft 4 as well as by the bottom and side wall of the cylinder wall 16. The sleeve 6 is inserted into the open end of this hydraulic chamber and forms a piston in this hydraulic chamber. The hydraulic chamber is connected to a hydraulic line 17, which, in the example shown, is arranged inside the output shaft 4, which is designed as a hollow shaft, and leads out at one end of the output shaft 4. This hydraulic line 17 is coupled in particular to a hydraulic pump (not shown).

[0046] To rotate the first rotor disk R1 counterclockwise relative to the second rotor disk R2, hydraulic fluid is pumped into the hydraulic chamber by means of the hydraulic pump, whereby the sleeve 6 is displaced axially to the right on the output shaft 4. The return device 15, designed here as a spring unit, is thereby tensioned. Due to the intermeshing helical gears 9, 11 of the sleeve 6 and the rotor shaft 5, the rotor shaft 5 and thus the first rotor disk R1, which is firmly connected to the rotor shaft 5, is thereby rotated counterclockwise relative to the output shaft 4 and thus relative to the second rotor disk R2, which is non-rotatably connected to the output shaft 4.In order to maintain the correspondingly rotated position of the first rotor disk R1 without leaving the hydraulic pump constantly activated, a valve can be provided in the hydraulic line 17, for example, which is closed after this rotation of the first rotor disk R1, so that an outflow of the hydraulic fluid from the hydraulic chamber is prevented.

[0047] To rotate the first rotor disk R1 in the opposite direction, i.e. to reset it, the hydraulic pump is switched off in the example shown or it is already switched off, and if the valve is provided in the hydraulic line 17, this valve is opened. As a result, the sleeve 6 is displaced axially to the left on the output shaft 4 by means of the tensioned reset device 15, which is designed here as a spring unit, whereby the hydraulic fluid is forced out of the hydraulic chamber. Due to the intermeshing helical gears 9, 11 of the sleeve 6 and the rotor shaft 5, the rotor shaft 5 and thus the first rotor disk R1 which is fixedly connected to the rotor shaft 5 is rotated back clockwise relative to the output shaft 4 and thus relative to the second rotor disk R2 which is connected in a rotationally fixed manner to the output shaft 4.

[0048] The return device 15, designed here as a spring unit, is supported, as described, on the one hand on the Fig. 4 right end face of the sleeve 6 and on the other hand in the example shown on a radial support wall 18 arranged or formed on the outer wall of the output shaft 4.

[0049] In the example according to Fig. 5, the actuator device 12 also has the Fig. 4, which acts on one end face of the sleeve 6, here also on the left end face, in the axial direction and is designed to displace the sleeve 6 axially in one direction, in Fig. 5 also to the right. This hydraulic device 14 is directed to the Fig. 4 described manner and functions in the manner to be Fig. 4 described manner.

[0050] Also in Fig. 5, the actuator device 12 further comprises the return device 15 acting on the other end face of the sleeve 6, here also on the right end face, in the axial direction, which is designed to displace the sleeve 6 axially in the opposite direction, in Fig. 5 thus to the left. In the embodiment according to Fig. 5, this return device 15 is designed as a further hydraulic device.

[0051] This additional hydraulic device also has, in particular, a hydraulic chamber that can be filled with hydraulic fluid. This hydraulic chamber is shown in the embodiment according to Fig. 5 is formed by the outer wall of the output shaft 4, a cylinder base 19 aligned radially to the output shaft 4 and arranged or formed on the output shaft 4, and the rotor shaft 5. The sleeve 6 is inserted into the open end of this hydraulic chamber of the return device 15 designed as a further hydraulic device and thus also forms a piston in this hydraulic chamber. This hydraulic chamber is connected to a further hydraulic line 20, which in the example shown is also arranged inside the output shaft 4 designed as a hollow shaft and leads out at an end face of the output shaft 4, here at the same end face as the hydraulic line 17. This further hydraulic line 20 is in particular also coupled to the hydraulic pump (not shown).

[0052] To rotate the first rotor disk R1 relative to the second rotor disk R2 counterclockwise, hydraulic fluid is pumped into the hydraulic chamber of the hydraulic device 14 by means of the hydraulic pump, causing the sleeve 6 to be displaced axially to the right on the output shaft 4. Due to the displacement of the sleeve 6 into the hydraulic chamber of the return device 15, the hydraulic fluid is forced out of this hydraulic chamber of the return device 15.

[0053] Due to the intermeshing helical gears 9, 11 of sleeve 6 and rotor shaft 5, rotor shaft 5 and thus the first rotor disk R1, which is firmly connected to rotor shaft 5, is rotated counterclockwise relative to output shaft 4 and thus relative to the second rotor disk R2, which is non-rotatably connected to output shaft 4. In order to maintain the correspondingly rotated position of first rotor disk R1 without constantly activating the hydraulic pump, a valve can also be provided in hydraulic line 17 and / or in further hydraulic line 20, for example, which is closed after this rotation of first rotor disk R1, so that an outflow of hydraulic fluid from the hydraulic chamber of hydraulic device 14 and / or from the hydraulic chamber of return device 15 is prevented.The valve or the respective valve is then opened only when the hydraulic fluid is to flow into or out of the respective hydraulic chamber.

[0054] To rotate the first rotor disk R1 in the opposite direction, i.e., to reset it, hydraulic fluid is pumped into the hydraulic chamber of the reset device 15 by means of the hydraulic pump in the example shown, causing the sleeve 6 to be displaced axially to the left on the output shaft 4. Due to the displacement of the sleeve 6 into the hydraulic chamber of the hydraulic device 14, the hydraulic fluid is forced out of this hydraulic chamber of the hydraulic device 14.

[0055] Due to the intermeshing helical gears 9, 11 of sleeve 6 and rotor shaft 5, rotor shaft 5 and thus the first rotor disk R1 fixedly connected to rotor shaft 5 is rotated back clockwise relative to output shaft 4 and thus relative to second rotor disk R2 which is non-rotatably connected to output shaft 4.

[0056] In the example according to Fig. 6, the hydraulic device 14 is arranged on a housing 21 of the axial flow machine 2 and, in the example shown, is connected to the sleeve 6 via a rolling bearing 22 or, alternatively, for example, via a plain bearing. In this way, a release bearing is realized, by which the housing-fixed hydraulic device 14 is coupled to the sleeve 6 in the axial direction and is rotationally decoupled from the sleeve 6, which rotates during operation of the axial flow machine 2.

[0057] The hydraulic device 14 also acts on one end face, here also on the left end face, of the sleeve 6 in the axial direction via the roller bearing 22. It is also designed to move the sleeve 6 axially in one direction, in Fig. 6 to the right. Here, too, the actuator device 12 further comprises the return device 15 acting on the other end face of the sleeve 6 in the axial direction, which is designed to displace the sleeve 6 axially in the opposite direction, in Fig. 6 thus to the left. The return device 15 is in the embodiment according to Fig. 6 trained as in Fig. 4 shown and described, ie as a spring unit, but can alternatively also be designed as in Fig. 5 shown and described, ie as an additional hydraulic device.

[0058] The hydraulic device 14 also has a hydraulic chamber that can be filled with hydraulic fluid. This hydraulic chamber is shown in the embodiment according to Fig. 6, however, is formed by the housing 21 or a formation formed or arranged on the housing 21. A piston 23 is inserted into the open end of this hydraulic chamber. The hydraulic chamber is also connected here to the hydraulic line 17. This hydraulic line 17 is coupled in particular to the hydraulic pump (not shown).

[0059] The piston 23 rests against a bearing shell 24 of the rolling bearing 22 facing the piston 23. The sleeve 6 rests with its end face, here the left end face, against a bearing shell 25 of the rolling bearing 22 facing the sleeve 6. The bearing shells 24, 25 are rotationally decoupled from each other by rolling elements 26, for example, balls or rollers.

[0060] To rotate the first rotor disk R1 relative to the second rotor disk R2 counterclockwise, hydraulic fluid is pumped into the hydraulic chamber by the hydraulic pump, forcing the piston 23 out of the hydraulic chamber, axially displacing the rolling bearing 22, to the left in the example shown, and thereby also axially displacing the sleeve 6 on the output shaft 4 to the right via the rolling bearing 22. The return device 15, designed here as a spring unit, is thereby tensioned.

[0061] Due to the intermeshing helical gears 9, 11 of sleeve 6 and rotor shaft 5, rotor shaft 5 and thus the first rotor disk R1, which is firmly connected to rotor shaft 5, is rotated counterclockwise relative to output shaft 4 and thus relative to the second rotor disk R2, which is non-rotatably connected to output shaft 4. In order to maintain the correspondingly rotated position of first rotor disk R1 without constantly activating the hydraulic pump, a valve can also be provided in hydraulic line 17, for example, which is closed after this rotation of first rotor disk R1, thus preventing hydraulic fluid from flowing out of the hydraulic chamber.

[0062] To rotate the first rotor disk R1 in the opposite direction, i.e. to reset it, the hydraulic pump is switched off in the example shown or is already switched off, and if the valve is provided in the hydraulic line 17, this valve is opened. As a result, the sleeve 6 is displaced axially to the left on the output shaft 4 by means of the tensioned return device 15, which is designed here as a spring unit, and in doing so displaces the rolling bearing 22 and thus also the piston 23 to the left. By pushing the piston 23 into the hydraulic chamber, the hydraulic fluid is pressed out of the hydraulic chamber. Due to the intermeshing helical gears 9, 11 of the sleeve 6 and the rotor shaft 5, the rotor shaft 5 and thus the first rotor disk R1 which is fixedly connected to the rotor shaft 5 is rotated back clockwise relative to the output shaft 4 and thus relative to the second rotor disk R2 which is connected in a rotationally fixed manner to the output shaft 4.

[0063] If the reset device 15 is designed as in Fig. 5, i.e. as a further hydraulic device, then during the rotation of the first rotor disk R1 relative to the second rotor disk R2 in the counterclockwise direction, the hydraulic fluid is also pressed out of this hydraulic chamber of the return device 15 due to the displacement of the sleeve 6 into the hydraulic chamber of the return device 15. Due to the intermeshing helical gears 9, 11 of the sleeve 6 and the rotor shaft 5, the rotor shaft 5 and thus the first rotor disk R1 fixedly connected to the rotor shaft 5 is rotated counterclockwise relative to the output shaft 4 and thus relative to the second rotor disk R2 which is connected in a rotationally fixed manner to the output shaft 4.

[0064] In order to maintain the correspondingly rotated position of the first rotor disk R1 without leaving the hydraulic pump constantly activated, a valve can also be provided in the hydraulic line 17 and / or in the then also present further hydraulic line 20, for example, which is closed after this rotation of the first rotor disk R1, so that an outflow of the hydraulic fluid from the hydraulic chamber of the hydraulic device 14 and / or from the hydraulic chamber of the return device 15 is prevented. In this example, the valve or the respective valve is then also opened in particular only when the hydraulic fluid is to flow into or out of the respective hydraulic chamber.

[0065] In order to rotate the first rotor disk R1 in the opposite direction, i.e. to reset it, by means of the reset device 15 designed as a further hydraulic device, hydraulic fluid is pumped into the hydraulic chamber of the reset device 15 by means of the hydraulic pump, as a result of which the sleeve 6 on the output shaft 4 is displaced axially to the left and thus the rolling bearing 22 and, via this, the piston 23 axially to the left. Due to the displacement of the piston 23 into the hydraulic chamber of the hydraulic device 14, the hydraulic fluid is pressed out of this hydraulic chamber of the hydraulic device 14. Due to the intermeshing helical gears 9, 11 of the sleeve 6 and the rotor shaft 5, the rotor shaft 5 and thus the first rotor disk R1 which is fixedly connected to the rotor shaft 5 is rotated back clockwise relative to the output shaft 4 and thus relative to the second rotor disk R2 which is connected in a rotationally fixed manner to the output shaft 4.

[0066] The hydraulic pump is in particular an electric hydraulic pump.

[0067] The described adjustment device 7 thus enables a rotor phase adjustment for field weakening. In the described embodiments, this rotor phase adjustment is carried out hydraulically, at least in one direction. The reset occurs, for example, mechanically, in particular by means of the spring unit, or also hydraulically.

[0068] The phase shift of the rotor disks R1, R2 can, for example, reach a maximum of 180°. Depending on the number and arrangement of pole pairs on the rotor disks R1, R2, this requires, for example, a maximum rotation of the first rotor disk R1 relative to the second rotor disk R2 of 30°. This converts the axial flux machine 2, which is designed as an NS type (north pole N against south pole S) with the two rotor disks R1, R2 in a non-rotated basic position, into an axial flux machine 2 designed as an NN type (north pole N against north pole N).

[0069] In the respective end position of the rotor rotation, a respective maximum position of the rotor phase shift is thus reached, i.e., for example, 0° or 180°. Further positions in between are possible. By adjusting the hydraulic pressure in the hydraulic device 14 and in the reset device 15, if this is designed as an additional hydraulic device, the first rotor disk R1 can also be rotated into any desired position relative to the second rotor disk R2 between the two maximum positions and held there, i.e., with a rotor phase shift between 0° and 180°.

[0070] In particular, it is provided that a load is coupled to the output shaft 4 and can thus be driven by the axial flow machine 2.

[0071] The following describes the function of the axial flux machine 2 with the phase shift enabled by the described solution. With a 0° phase shift, the axial flux machine 2 operates like a conventional axial flux machine, where no phase shift is possible. The adjustment device 7 enables the rotation of the rotor disks R1, R2 relative to each other, so that the magnetic path can be adjusted during normal operation.

[0072] In Fig. In Figure 7, solid lines represent the field-weakening position, and dashed lines represent the initial position without rotation of the first rotor disks R1 relative to the second rotor disk R2. This rotation of the first rotor disks R1 relative to the second rotor disk R2 causes the path of the magnetic flux MF in the air gap to become oblique. This is equivalent to an increase in the length of the air gap. This increases the magnetic resistance, and the magnetic flux density in the air gap is reduced in the field-weakening position. The change in the phase shift angle can be continuous or discontinuous. By changing operating points, the adjustment device 7 can control the phase shift between the rotor disks R1, R2, so that the air gap flux is actively adjusted based on the current operating point. Therefore, a high negative d-current injection in the field-weakening range is not required.The axial flux machine 2 can achieve better efficiency and deliver more torque compared to the conventional axial flux machine in the field weakening range.

[0073] As already mentioned above, with the solution described here, the rotor phases can be shifted by 180° and thus converted from the LV type to the NN type. This means that the remaining flux in the air gap is very small, since there is no yoke in the stator 3. In this case, the induced voltage in the stator 3 is very low and the axial flux machine 2 or the entire drive device 1 goes into a mechanically safe state that is similar to the electrically safe state, i.e., an active short circuit. In some critical cases where an active short circuit is not available, the axial flux machine 2 can, by means of the solution described here, i.e., by means of the adjustment device 7 and the rotor phase shift enabled thereby, thus go into the mechanically safe state in a way that is alternative to the active short circuit.In addition, this mechanically safe state has no time limit and does not generate any additional power loss in the axial flux machine 2 and in a converter.

[0074] Another critical problem is the axial force of the axial flux machine 2, which can lead to contact between the rotor, i.e., the rotor disks R1, R2, and the stator 3. Even at standstill without stator currents, a high axial force is present. With the adjustment device 7, the rotor phases can be shifted by 180° at standstill in the manner described above. This can significantly reduce the axial force at standstill.

[0075] Fig.Figure 8 shows an embodiment of the electric drive device 1, which is designed as a wheel hub drive of a vehicle. It comprises the axial flux machine 2 and a transmission 8. The axial flux machine 2 is coupled via the transmission 8 to a wheel hub and thus to a wheel 10 of the vehicle attached to the wheel hub.

[0076] The axial flux machine 2 is ideal for this application due to its high torque density and compact design. However, accommodating the entire electric drive system 1—in particular, the converter, axial flux machine 2, gearbox 8, and also a braking device (not shown here)—in such a limited space is a major challenge.

[0077] To meet safety requirements, the axial flux machine 2, which has permanent magnets, must be decoupled from the wheel 10 if a critical fault occurs in the electric drive system 1. In conventional electric drive systems, a separation unit is provided for this purpose. This can be arranged between the output of the axial flux machine 2 and the wheel 10, before the transmission 8, or after the transmission 8. Therefore, additional installation space is required for this separation unit and a control system for the separation unit.

[0078] With the solution described here, this separation unit is no longer required, because the adjusting device 7 allows the rotor phases to be shifted by up to 180° in the manner described, thus achieving the mechanically safe state. With the solution described, the wheel 10, or more precisely the wheel hub and, via this, the wheel 10, can be driven by the axial flux machine 2 directly or via the gearbox 8. The wheel hub or the gearbox 8, in particular its input shaft, is coupled to the output shaft 4 for this purpose. The solution described thus saves installation space in the wheel 10, and the axial flux machine 2 can be arranged closer to the wheel 10.

Claims

[1] Electric drive device (1) with an axial flux machine (2), wherein the axial flux machine (2) comprises: - a first rotor disc (R1) on which first magnetic elements (M1) are arranged, - a second rotor disc (R2) on which second magnetic elements (M2) are arranged, and - a stator (3) arranged between the rotor discs (R1, R2), characterized by an output shaft (4) which is connected to the second rotor disc (R2) in a rotationally fixed manner, and an adjusting device (7) by means of which the first rotor disc (R1) can be rotated relative to the second rotor disc (R2), wherein the adjusting device (7) comprises: - a rotor shaft (5) which is firmly connected to the first rotor disc (R1) and is axially fixed, - a sleeve (6) which is arranged on the output shaft (4) and in the rotor shaft (5), is connected to the output shaft (4) in a rotationally fixed manner, is arranged axially displaceably on the output shaft (4) and has on a sleeve outer circumference a helical toothing (9) which engages in a corresponding helical toothing (11) on a rotor shaft inner circumference of the rotor shaft (5), and - an actuator device (12) which is designed to axially displace the sleeve (6) on the output shaft (4), and wherein the actuator device (12) has a hydraulic device (14) acting on a front side of the sleeve (6) in the axial direction, with a hydraulic chamber that can be filled with hydraulic fluid, wherein the sleeve (6) is inserted into an open end of the hydraulic chamber and forms a piston in the hydraulic chamber, and wherein the hydraulic chamber is connected to a hydraulic line (17) which is arranged inside the drive shaft (4) designed as a hollow shaft. [2] Electric drive device (1) according to claim 1, characterized by that the magnetic elements (M1) of the first rotor disc (R1) and / or the magnetic elements (M2) of the second rotor disc (R2) are each designed as a permanent magnet. [3] Electric drive device (1) according to one of the preceding claims, characterized by that the actuator device (12) has a hydraulic device (14) acting on an end face of the sleeve (6) in the axial direction, which is designed to displace the sleeve (6) axially in one direction. [4] Electric drive device (1) according to claim 3, characterized by that the hydraulic device (14) is arranged on a housing (21) of the axial flow machine (2) and is connected to the sleeve (6) via a rolling bearing (22) or plain bearing. [5] Electric drive device (1) according to claim 3 or 4, characterized by that the actuator device (12) has a return device (15) acting in the axial direction on the other end face of the sleeve (6) and designed to displace the sleeve (6) axially in the opposite direction. [6] Electric drive device (1) according to claim 5, characterized by that the return device (15) is designed as a spring unit or as a further hydraulic device. [7] Electric drive device (1) according to one of the preceding claims, characterized by that a load is coupled to the output shaft (4). [8] Electric drive device (1) according to one of the preceding claims, designed as a wheel hub drive of a vehicle or for a vehicle. [9] Electric drive device (1) according to claim 8, characterized bythat a wheel hub and / or a wheel (10) of the vehicle is / are coupled to the output shaft (4). [10] Electric drive device (1) according to one of the preceding claims, characterized by a transmission (8), wherein a transmission input shaft is coupled to the output shaft (4).

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