Electric rotary machine, electric drive system and geared motor unit

Abstract

An electric rotary machine with a rotor (20) arranged on a rotor shaft (30), wherein the rotor (20) is supported at least partially in the radial direction by means of a rotary bearing (40) and the axial degree of freedom of the rotary bearing (40) is blocked along an axial direction by means of a contact element (50), and wherein the electric rotary machine comprises at least one grounding element (61) which is fixed to one of the two components, contact element (50) and rotor shaft (30), and forms a sliding contact (63) on the other component, wherein both the rotary bearing (40) and the grounding element (61) are arranged at least partially within a space radially bounded by the rotor (20) of the electric rotary machine, characterized in that - the earthing element (61) is part of an earthing unit (60) of the electric rotating machine, wherein the earthing unit (60) further comprises an earthing ring (62) which is arranged on the component to which the earthing element (61) is not fixed, wherein the sliding contact (63) is formed between the earthing element (61) and the earthing ring (62), - the earthing element (61) is arranged axially directly next to the rotary bearing (40), - the grounding element (61) is fixed to the component by means of a clamp and the clamping is realized by means of a clamping sleeve (80), - wherein the clamping sleeve (80) is designed as an angled sleeve, wherein an elongated hollow cylinder is connected to the axially flat component of the clamping sleeve (80), which is force-fitted in the component which serves to fix the earthing element (61) in a correspondingly complementary shaped shoulder.

Description

[0001] The invention relates to an electric rotary machine, an electric drive system with the electric rotary machine and a geared motor unit with the electric rotary machine.

[0002] Electric drive machines are known from the prior art in many industrial applications and are increasingly used in the automotive industry. Such a machine comprises a stator and a rotor that rotates relative to it. The rotor typically includes a rotor shaft, balancing laminations, rotor lamination stacks, and magnets.

[0003] Especially for applications in electrically powered vehicles, there is a requirement to achieve the necessary power output within the available installation space. Accordingly, the electric rotary machine must be designed as a very compact radial flux machine or as an axial flux machine. The installation space required for the power electronics associated with the respective electric rotary machine must also be taken into account.

[0004] DE 10 2020 111 925 A1 discloses an electric drive for a vehicle with an electric motor, wherein the electric motor has a rotor and a stator, with a rotor shaft, wherein the rotor shaft has a rotor shaft section, with a housing section, with a current path for discharging an electric charge and / or voltage from the housing section and / or from the stator as a first discharge partner to the rotor shaft section as a second discharge partner, with a bypass section, wherein the bypass section is arranged on the housing section and forms part of the current path, and wherein the bypass section and the housing section are designed as a common section.

[0005] The DE 11 2018 006 726 T5 shows a rotating electric machine.

[0006] US 2011 / 0 309 726 A1 and US 2020 / 0 177 062 A1 each also show an electric rotary machine.

[0007] From EP 2 733 827 A1, an electric motor is known which comprises a motor housing in which an interior space is formed, and a bearing arranged so that it extends through a wall of the motor housing. Furthermore, a rotor shaft is provided, rotatably supported by the bearing, as well as an earth conductor attached to the motor housing, a frame, and an electrical conductor provided on the frame. The frame has an annular or curved inner circumferential surface along an outer circumference of the rotor shaft and is attached to the motor shaft. The electrical conductor is arranged on the inner circumferential surface of the frame such that one end of the electrical conductor is in sliding contact with the rotor shaft. A bypass flow passage is provided between the earth conductor and the motor housing. The interior space and an outer surface of the motor housing are connected to each other via the bypass flow passage.

[0008] In Fig. Figure 1 shows a section of a geared motor unit with another conventional electric rotary machine in an embodiment as an axial flux machine. A rotor 20 is arranged on a rotation axis 1, which has two rotor units 21, 22 spaced apart from each other. The rotor units 21, 22 are fixed to one another by means of screw connections 31. The stator 10 of the electric rotary machine is located between these two rotor units 21, 22. The rotor 20 and its second rotor unit 22 integrally form a rotor shaft 30. The rotor shaft 30 is designed as a hollow shaft 32. The rotor shaft 30 is coupled to a shaft journal 101 of a gearbox input shaft 100 of an attached gearbox by means of a splined connection 102. In particular, the gearbox can be a planetary gearbox, so that the gearbox input shaft 100 can also be referred to as a sun shaft. The rotor 20 is supported by means of a rotary bearing 40.The rotary bearing 40 is supported on its radial inner side by a motor support element 71, which in turn is fixedly arranged in a housing 70 of the electric rotary machine or is formed as an integral part of this housing 70. The axial degree of freedom of the rotary bearing 40 is blocked along one axial direction by means of a contact element 50. The contact element 50 has a rotationally symmetrical cross-section and is fixed to the motor support element 71 by means of a screw 84. On the axially opposite side, the rotary bearing 40 is fixed by means of a snap ring 85. The electric rotary machine further comprises a grounding unit 60, which is arranged radially between the rotor shaft 30 and the housing 70. The grounding unit 60 comprises a grounding element 61, which forms a sliding contact 63 on the rotor shaft 30.The grounding element 61 can be in the form of a grounding ring or pin, which is firmly seated in the housing 70, in which the stator 10 is also connected. The sliding contact 63 can be implemented using brushes.

[0009] The formation of a contact is necessary to prevent current passage through the rotary bearing 40, as there is a risk that current passages could damage the raceway of the rolling elements of the rotary bearing 40.

[0010] Furthermore, the electric rotary machine includes a radial shaft seal 90, which in the embodiment shown here is arranged radially between the gearbox input shaft 100 and the housing 70.

[0011] The grounding unit 60 on the rotor shaft 30 and the radial shaft seal 90 on the gearbox input shaft 100 are located axially next to each other and require a correspondingly large amount of installation space due to their own volume but also due to required safety distances.

[0012] Long tolerance chains must be observed when arranging the grounding unit 60 and the radial shaft seal 90, as the positions of both elements are influenced by tolerance chains through a connected gearbox. Significant deviations from the theoretically required position of the grounding unit 60 further increase the risk of current flow through the rotary bearing 40, despite the installed grounding. Furthermore, the grounding unit 60 and the radial shaft seal 90 must be arranged on a relatively large diameter, meaning that these elements must be able to withstand relatively high circumferential speeds and the associated frictional losses.

[0013] Based on this, the present invention aims to provide an electric rotary machine, an electric drive system and a geared motor unit with which an efficient drive can be ensured in a simple, cost-effective and space-saving manner.

[0014] This task is solved by the subject matter of the claims.

[0015] The features of the claims can be combined in any technically meaningful way, taking into account the explanations from the following description as well as features from the figures, which include supplementary embodiments of the invention.

[0016] Within the scope of the present invention, the terms “radial” and “axial” always refer to the axis of rotation of the electric rotary machine.

[0017] The invention relates to an electric rotary machine with a rotor arranged on a rotor shaft, wherein the rotor is supported at least partially in a radial direction by means of a rotary bearing and the axial degree of freedom of the rotary bearing is blocked along an axial direction by means of a support element.

[0018] The electric rotary machine comprises at least one grounding element that is fixed to one of the two components, the mounting element and the rotor shaft, and forms a sliding contact with the other component, wherein both the rotary bearing and the grounding element are arranged, at least partially, within a space radially bounded by the rotor of the electric rotary machine. In an advantageous embodiment, the rotary bearing and the grounding element are arranged completely within the space radially bounded by the rotor of the electric rotary machine.

[0019] The electric rotary machine can be an axial flux machine, although the realization of the invention in a radial flux machine is not excluded.

[0020] One embodiment provides that the grounding element is fixed to the system element and forms a sliding contact on the rotor shaft.

[0021] The mounting element can be fixed axially to a motor support element by means of a screw or screw connection. This motor support element is fixed to a housing of the electric rotary machine or is integrally formed by it.

[0022] Due to the essentially space-neutral arrangement of the grounding element within the space surrounding the rotor, axial installation space can be made available.

[0023] The arrangement of the grounding element according to the invention also makes it possible to realize the sliding contact on a very small diameter, thereby reducing friction losses in the sliding contact and increasing efficiency accordingly.

[0024] The grounding element can be part of a grounding unit of the electric rotary machine, wherein the grounding unit further comprises a grounding ring arranged on the component to which the grounding element is not fixed, and wherein the sliding contact between the grounding element and the grounding ring is formed. In the embodiment in which the grounding element is fixed to the mounting element, the grounding ring is accordingly part of the rotor shaft or is electrically conductively attached to it, so that the sliding contact between the grounding element and the rotor shaft is indirectly formed.

[0025] In particular, the grounding element can be arranged axially directly adjacent to the rotary bearing. This means that no other machine element is located between the rotary bearing and the grounding element or the entire grounding system. Any axial distance between the rotary bearing and the grounding element is then solely due to the required installation space of the component to which the grounding element is attached. This very close arrangement of the grounding element on the rotary bearing results in a comparatively short tolerance chain for the grounding element, since its position is determined only by the position or dimensions of a motor mounting element on which the rotary bearing sits.Furthermore, this very close arrangement of the grounding element on the rotary bearing greatly reduces the risk of parallel currents forming through the rotary bearing and any splined connection between the rotor shaft and a gearbox input shaft, thus preventing sparking and corresponding damage to the rotary bearing or splined connection.

[0026] According to the invention, the electric rotary machine provides that the grounding element is fixed to the component by means of a clamp. This clamping is achieved by means of a clamping sleeve. In particular, the grounding element can be essentially in the form of a flat hollow cylinder or a disc. The clamping sleeve can also, at least partially, have the form of a disc or a flat hollow cylinder that rests against the grounding element in the axial direction.

[0027] To achieve a sufficiently stable, force-fit connection, an elongated hollow cylinder can be attached to the axially flat component of the clamping sleeve. This cylinder is force-fitted into a correspondingly complementary shaped shoulder in the component that serves to fix the grounding element. Such a design can also be referred to as an angled sleeve and allows for the simple and space-saving attachment of the grounding element, for example, to the rotor shaft.

[0028] Furthermore, the electric rotary machine can include a radial shaft seal that provides a seal between the rotor shaft and the housing of the electric rotary machine. If the electric rotary machine is part of an electric drive system and / or a geared motor unit, the housing can also be that of the electric drive system or the geared motor unit.

[0029] Accordingly, the design according to the invention allows the radial shaft seal to be located not on a gearbox input shaft, which, in the case of a planetary gear transmission, is referred to as the sun shaft, but closer to the rotor or rotary bearings. This further enables the radial shaft seal to be designed with a correspondingly smaller diameter and, consequently, to achieve a sealing effect over a smaller circumference. This embodiment can be further enhanced by the additional placement of an O-ring between the gearbox input shaft and the rotor shaft. Overall, the arrangement of the radial shaft seal according to the invention between the rotor shaft and the housing of the electric rotary machine can further contribute to reducing the axial installation space required.

[0030] The electric rotary machine can be an axial flux machine whose rotor comprises two axially spaced rotor units, the rotor shaft being an integral part of one of the two rotor units, and the two rotor units being rigidly connected to each other by means of bolted connections. The stator of the axial flux machine is located between the spaced-apart rotor units. When the electric rotary machine is coupled to a gearbox, a first rotor unit, which is arranged axially closer to the gearbox input shaft than the second rotor unit, can form the rotor shaft integrally.

[0031] In an alternative embodiment, it is provided that the second rotor unit, which is arranged axially on the side of the electric rotary machine facing away from the gearbox input shaft, forms the rotor shaft integrally.

[0032] Another aspect of the present invention is an electric drive system comprising several electric rotary machines, at least one of which is designed according to the invention, wherein the axes of rotation of the rotor shafts of the electric rotary machines are arranged on an ideal axis.

[0033] An alternative embodiment of an electric drive system provides that an electric axle drive is realized with an electric rotary machine designed according to the invention, wherein an output shaft coupled to the rotor shaft of the electric rotary machine, which may optionally be a drive shaft of a motor vehicle or a transmission input shaft, runs parallel to the axis of the rotor shaft of the electric rotary machine.

[0034] The electric rotary machines according to the invention can be designed as radial flux machines or as axial flux machines. In the case of the axial flux machine design, they can be arranged in a so-called H-arrangement or I-arrangement, which means that in an I-arrangement, the power electronics assigned to each electric rotary machine are also arranged on the common axis, namely between the two electric rotary machines, and in an H-arrangement, the power electronics assigned to the two electric rotary machines are axially offset from the common axis on which the axes of rotation of the two electric rotary machines lie.

[0035] Furthermore, the invention provides a geared motor unit which comprises at least one electric rotary machine or electric drive system according to the invention, and has a gearbox whose gearbox input shaft is coupled or can be coupled to the rotor shaft of the electric rotary machine.

[0036] The rotor shaft of the electric rotary machine can be designed, at least in sections, as a hollow shaft, and the gearbox input shaft can have a journal positioned within the hollow shaft. A seal can be arranged between the journal of the gearbox input shaft and the hollow shaft.

[0037] Alternatively or additionally, the hollow shaft can also be axially sealed liquid-tight by means of a sealing cover.

[0038] In addition to the seal position, a torque transmission device can be arranged, such as a splined connection between the input shaft journal of the gearbox and the hollow shaft or the hollow shaft section of the rotor shaft. The seal used between the input shaft journal of the gearbox and the hollow shaft can, in particular, be an O-ring.

[0039] When using the sealing cover, it is necessary to provide a mounting option for the system element if it is to be attached to a motor support element on which the rotary bearing is also located.

[0040] In this case, it must be ensured that the mounting element can be installed through the motor support element, for example by using a threaded sleeve and a threaded bolt that can be screwed into the threaded sleeve, with the threaded sleeve simultaneously forming the clamping sleeve. The appropriate torque can be applied to tighten the threaded bolt and threaded sleeve from the side axially opposite the sealing cover.

[0041] Another way to simplify assembly in this case is to divide the rotor such that the second rotor unit, which is arranged axially on the side of the electric rotary machine facing away from the gearbox input shaft, forms an integral part of the rotor shaft. In this embodiment as well, when using a sealing cover, the mounting element can be assembled in a simplified manner, namely together with the positioning and mounting of the rotary bearing and the second rotor unit.

[0042] Another advantage of the design with a sealing cover is that a splined connection between the rotor shaft and the gearbox input shaft is located in the gearbox oil chamber, which prevents wear phenomena such as fretting corrosion.

[0043] The invention described above is explained in detail below against the relevant technical background with reference to the accompanying drawings, which show preferred embodiments. The invention is in no way limited by the purely schematic drawings, and it should be noted that the embodiments shown in the drawings are not limited to the dimensions depicted. The drawings show... Fig. 1: a section of a conventional geared motor unit with a conventional electric rotary machine, Fig. 2: a section of a geared motor unit according to the invention with an electric rotary machine according to the invention of a first embodiment, Fig. 3: a section of a geared motor unit according to the invention with an electric rotary machine according to the invention of a second embodiment, Fig. 4: a section of a geared motor unit according to the invention with an electric rotary machine according to the invention of a third embodiment, Fig. 5: a section of a geared motor unit according to the invention with an electric rotary machine according to the invention of a fourth embodiment, and Fig. 6: a section of a geared motor unit according to the invention with an electric rotary machine according to the invention of a fifth embodiment.

[0044] On Fig. Reference has already been made to point 1 to explain the state of the art.

[0045] The general structure of a geared motor unit according to the invention with an electric rotary machine according to the invention as an axial flux machine is described in relation to Fig. 2 explained, in which a section of the geared motor unit with the electric rotary machine of a first embodiment is shown.

[0046] A rotor 20 is arranged on a rotational axis 1 and has two rotor units 21 and 22 spaced apart from each other. The rotor units 21 and 22 are fixed to one another by means of screw connections 31. The stator 10 of the electric rotary machine is located between these two rotor units 21 and 22. The rotor 20 and its second rotor unit 22 integrally form a rotor shaft 30. The rotor shaft 30 is designed as a hollow shaft 32. The rotor shaft 30 is coupled to a shaft journal 101 of a gearbox input shaft 100 of an attached gearbox by means of a splined connection 102. In particular, the gearbox can be a planetary gearbox, so that the gearbox input shaft 100 can also be referred to as a sun shaft.

[0047] The rotor 20 is supported by means of a rotary bearing 40. The rotary bearing 40 is supported on its radial inner side by a motor support element 71, which in turn is fixedly arranged in a housing 70 of the electric rotary machine or is formed as an integral part of this housing 70.

[0048] The axial degree of freedom of the rotary bearing 40 is blocked along one axial direction by means of a support element 50. The support element 50 has a rotationally symmetrical cross-section and is fixed to the motor mounting element 71 by means of a screw 84. On the axially opposite side, the rotary bearing 40 is fixed by means of a snap ring 85.

[0049] The electric rotary machine further comprises a grounding unit 60, which is arranged radially between the rotor shaft 30 and the mounting element 50. The grounding unit 60 includes a grounding element 61, which forms a sliding contact 63 on the rotor shaft 30. The grounding element 61 can be in the form of a grounding ring or pin, which is fixed to the mounting element 50. The sliding contact 63 can be implemented by means of brushes.

[0050] The formation of a contact is necessary to prevent current passage through the rotary bearing 40, as there is a risk that current passages could damage the raceway of the rolling elements of the rotary bearing 40.

[0051] The grounding element 61 is attached to the mounting element 50 by means of a clamping sleeve 80. The clamping sleeve 80 comprises a flat hollow cylinder 81, which is essentially disc-shaped, and which presses on the grounding element 61 along the axial direction, thus securing it between itself and the mounting element 50. The clamping sleeve 80 is held in place by an elongated hollow cylinder 82, which also forms part of the clamping sleeve 80 and which rests in or is pressed into a correspondingly complementary shaped shoulder 83 of the mounting element 50 to achieve this force-fit fixation.

[0052] Furthermore, the electric rotary machine comprises a radial shaft seal 90, which is arranged radially between the rotor shaft 30 and the housing 70. In the embodiment shown here, the electric rotary machine also comprises a seal 120, which may optionally be designed as an O-ring, between the gearbox input shaft 100 and the rotor shaft 30.

[0053] In the Fig. Figures 3-6 show further embodiments of the electric rotary machine and the geared motor unit according to the invention. In the following, only the differences compared to the one in Figure 3 will be discussed to explain these embodiments. Fig. The embodiment shown in section 2 is discussed in more detail below. Regarding identical components, please refer to the explanation in section 2. Fig. 2 referred.

[0054] Fig. Figure 3 shows a second embodiment, which differs from the first embodiment only in that the grounding unit 60 additionally comprises a grounding ring 62, which is arranged on the radial inner side of the rotor shaft 30, and on which the sliding contact 63 is realized by means of the grounding element 61. The grounding ring 62 is electrically connected to the rotor shaft 30.

[0055] The in Fig. The third embodiment shown in Figure 4 has a sealing cover 130 in the rotor shaft 30, which is designed as a hollow shaft 32, and which seals the hollow shaft 32. Accordingly, here too, contrary to the one shown in Fig. In the first embodiment shown in Figure 2, no seal is necessary between the gearbox input shaft 100 and the rotor shaft 30.

[0056] However, the embodiment shown here does not allow the installation of the system element 50 or the grounding unit 60 through the rotor shaft 30.

[0057] For easier installation of the system element 50 or the grounding unit 60, the following is included in the Fig. In the fourth embodiment shown in Figure 5, the mounting element 50 is simultaneously designed as a threaded sleeve 140 with an internal thread. A threaded bolt 141 can thus be inserted through the motor support element 71 from the side axially opposite the mounting element 50. Accordingly, the mounting element 50 and the grounding unit 60 can be easily mounted from this axial side.

[0058] A fifth embodiment is in Fig.Figure 6 is shown. In contrast to the previously described embodiments 1-4, here it is provided that the rotor shaft 30 is not integrally formed by the second rotor unit 22, but rather by the axially opposite first rotor unit 21. Here too, the two rotor units 21, 22 are fixed to one another by means of screw connections 31. Accordingly, the splined connection 102 between the gearbox input shaft 100 or its shaft journal 101 and the first rotor unit 21 is also implemented here.

[0059] The proposed electric rotary machine, electric drive system and geared motor unit provide equipment that ensures efficient drive in a simple, cost-effective and space-saving manner. Reference symbol list 1 axis of rotation 10 Stator 20 Rotor 21 First rotor unit 22 Second rotor unit 30 Rotor shaft 31 Screw connection 32 Hollow shaft 40 swivel bearings 50 plant element 60 earthing units 61 Earthing element 62 Grounding ring 63 Sliding contact 70 cases 71 Motor mounting element 80 clamping sleeve 81 flat hollow cylinder 82 elongated hollow cylinders Paragraph 83 84 screw 85 Snap ring 90 Radial shaft seal 100 Gearbox input shaft 101 wave pins 102 Splined connection 120 seals 130 sealing caps 140 threaded sleeve 141 threaded bolts

Claims

[1] Electric rotary machine with a rotor (20) arranged on a rotor shaft (30), wherein the rotor (20) is supported at least partially in a radial direction by means of a rotary bearing (40) and the axial degree of freedom of the rotary bearing (40) is blocked along an axial direction by means of a contact element (50), and wherein the electric rotary machine comprises at least one grounding element (61) which is fixed to one of the two components, contact element (50) and rotor shaft (30), and forms a sliding contact (63) on the other component, wherein both the rotary bearing (40) and the grounding element (61) are arranged at least partially within a space radially bounded by the rotor (20) of the electric rotary machine, characterized by , that - the earthing element (61) is part of an earthing unit (60) of the electric rotating machine, wherein the earthing unit (60) further comprises an earthing ring (62) which is arranged on the component to which the earthing element (61) is not fixed, wherein the sliding contact (63) is formed between the earthing element (61) and the earthing ring (62), - the earthing element (61) is arranged axially directly next to the rotary bearing (40), - the grounding element (61) is fixed to the component by means of a clamp and the clamping is realized by means of a clamping sleeve (80), - wherein the clamping sleeve (80) is designed as an angled sleeve, wherein an elongated hollow cylinder adjoins the axially flat component of the clamping sleeve (80), which is force-fitted in the component which serves to fix the earthing element (61) in a correspondingly complementary shaped shoulder. [2] Electric rotary machine according to claim 1, characterized by , that the electric rotary machine includes a radial shaft seal (90) which provides a sealing effect between the rotor shaft (30) and a housing (70) of the electric rotary machine. [3] Electric rotary machine according to one of the preceding claims, characterized by , that the electric rotary machine is an axial flux machine whose rotor (20) has two axially spaced rotor units (21,22) from each other, wherein the rotor shaft (30) is an integral part of one of the two rotor units (21,22) and the two rotor units (21,22) are firmly connected to each other by means of screw connections (31). [4] Electric drive system comprising several electric rotary machines, at least one of which is an electric rotary machine according to claim 1, wherein the rotation axes (1) of the rotor shafts (30) of the electric rotary machines are arranged on an ideal axis. [5] Geared motor unit comprising at least one electric rotary machine according to one of claims 1 to 3 or an electric drive system according to claim 4, and a gearbox whose gearbox input shaft (100) is coupled or can be coupled to the rotor shaft (30) of the electric rotary machine. [6] Geared motor unit according to claim 5, wherein the rotor shaft (30) is designed at least partially as a hollow shaft (32) and the gear input shaft (100) is designed with a shaft journal (101) which is positioned in the hollow shaft (32), wherein i) a seal (120) is arranged between the shaft journal (101) of the transmission input shaft (100) and the hollow shaft (32), and / or ii) the hollow shaft (32) is axially sealed liquid-tight by means of a sealing cover (130).

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