Electric rotating machine, electric drive system, and geared motor unit

Abstract

The invention relates to an electric rotating machine (10) having a rotor (12) which is mounted on a rotor shaft (8) and is radially supported at least partly by a rotary bearing (20), wherein the rotor shaft (8) has a coupling unit (6), which is designed for coupling to a gear unit input shaft (4), the rotary bearing (20) is a current-insulating rotary bearing (20), and the coupling unit (6) is a current-insulating coupling unit (6). The invention also relates to an electric drive system and to a geared motor unit (2).

Description

[0001] Electric rotary machine, electric drive system and geared motor unit

[0002] The invention relates to an electric rotary machine with a rotor arranged on a rotor shaft, which is at least partially supported in the radial direction by means of a rotary bearing, wherein the rotor shaft carries a coupling unit which is configured for coupling with a gearbox input shaft.

[0003] Electric rotary machines, in particular axial flux machines, are already known from the prior art. For example, DE 10 2022 101 754 A1 discloses an electric rotary machine with a rotor arranged on a rotor shaft, wherein the rotor is supported at least partially in the 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 contact element. Furthermore, the electric rotary machine comprises at least one grounding element, which is fixed to one of the two components, the contact 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.

[0004] However, the current state of the art has the disadvantage that parasitic currents cannot be dissipated via the stator, or only insufficiently.

[0005] The object of the invention is therefore to avoid or at least mitigate the disadvantages of the prior art. In particular, it aims to provide an axial flux machine in which damaging, parasitic currents via the rotor shaft can be avoided.

[0006] This problem is solved by the electric rotary machine according to claim 1, as well as by the electric drive system according to claim 9 and by the geared motor unit according to claim 10. In particular, this problem is solved in a generic device according to the invention by the fact that the rotary bearing is a current-insulating (electrically insulating or electrically high-impedance) rotary bearing and the coupling unit is a current-insulating (electrically insulating or electrically high-impedance) coupling unit.

[0007] Within the scope of the present invention, the terms “radial” and “axial” always refer to the axis of rotation of the electric rotary machine.

[0008] Advantageous embodiments are claimed in the dependent claims and are explained in more detail below.

[0009] In an advantageous embodiment, one axial degree of freedom of the rotary bearing can be blocked along an axial direction by means of a support element.

[0010] Preferably, the rotary bearing can be a rolling bearing with an inner ring, an outer ring, and a plurality of rolling elements guided between the inner and outer rings. It may be advantageous if the inner ring and / or the outer ring has an electrically insulating coating, preferably a ceramic coating. Alternatively or additionally, it may also be advantageous if the plurality of rolling elements is made of an electrically insulating material, preferably ceramic.

[0011] In one embodiment according to the invention, the electrically insulating coupling unit can have at least one torque-transmitting insulating element. That is, the coupling unit can have at least one element that transmits torque and simultaneously provides electrical insulation. It can be particularly advantageous if the coupling unit is designed as an Oldham coupling or a Vulkollan coupling. According to the invention, the coupling unit can further advantageously be configured to couple the rotor shaft to the transmission input shaft in a positive-locking and / or friction-locking manner.

[0012] According to an advantageous embodiment, the electronic rotary machine can have at least one grounding element. This grounding element can be fixed to one of the two components, the mounting element and the rotor shaft, and form a sliding contact and / or a capacitive transmission element on the other component. That is, the grounding element can be fixed to the mounting element and form a sliding contact on the rotor shaft. Alternatively, the grounding element can also be attached to the rotor shaft and form a sliding contact and / or a capacitive transmission element on the mounting element. It can be particularly advantageous if 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.

[0013] 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.

[0014] In a preferred embodiment, the grounding element and the coupling unit can be arranged radially adjacent to each other. That is, there is only a small distance between the grounding element and the coupling unit in the radial direction. Preferably, the grounding element can be arranged radially inside the coupling unit. This ensures targeted current dissipation.

[0015] Furthermore, it can be particularly advantageous if the grounding element, preferably contactless, is arranged radially inside the transmission input shaft. In particular, the transmission input shaft can be designed as a hollow shaft for this purpose, with the grounding element being housed within this hollow shaft. It can be advantageous if the grounding element has no contact with the transmission input shaft, i.e., the grounding element can be arranged contactlessly inside the transmission input shaft.

[0016] 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.

[0017] According to the invention, the grounding element can be designed as a locking unit or grounding pin, for example made of graphite. The locking unit can be an assembly consisting of a sleeve, a ball, and a spring, wherein the spring and the ball are received in the sleeve and the spring exerts a preload force on the ball.

[0018] 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.

[0019] The electric rotary machine can be an axial flux machine whose rotor comprises two axially spaced rotor units, with the rotor shaft being an integral / one-piece component of one of the two rotor units, and the two rotor units being rigidly connected to each other by means of screw connections. Alternatively, the two rotor units can also be connected to each other by any other connection. 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.

[0020] In other words, the invention relates to an electric rotary machine, in particular an axial flux machine, with rotor isolation, specifically from the gearbox. This is achieved by an insulated rotor bearing and an insulated coupling between the rotor and the gearbox input shaft. Optionally, additional grounding elements, such as a locking unit as a sacrificial bearing between the rotor and the stator housing, can be added.

[0021] 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. That is, the axes of rotation of the rotor shafts of the electric rotary machines are arranged coaxially with each other.

[0022] An alternative embodiment of an electric drive system provides for an electric axle drive 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. That is, the output shaft does not pass through the rotor and the transmission shaft. This allows the resulting installation space to be used for insulation and grounding.

[0023] The electrical rotary machines according to the invention can be designed as radial flux machines or as axial flux machines.

[0024] In the case of the implementation as axial flux machines, these can be arranged in a so-called Fl 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 to the common axis on which the axes of rotation of the two electric rotary machines lie.

[0025] 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 via the coupling unit.

[0026] 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. Alternatively or additionally, the hollow shaft can also be axially sealed by means of a sealing cap to prevent liquids from entering the shaft.

[0027] The invention is explained below with the aid of a drawing. It shows:

[0028] Fig. 1 shows a partial sectional view of a geared motor unit according to the invention in a preferred embodiment.

[0029] The figure is purely schematic and serves solely to illustrate the invention. The same elements are labelled with the same reference symbols.

[0030] Figure 1 shows a partial sectional view of a geared motor unit 2 according to a preferred embodiment of the invention. The geared motor unit 2 has a gear input shaft 4 which is coupled, or can be coupled, to a rotor shaft 8 of an electric rotary machine 10 via a current-insulating coupling unit 6 in a torque-transmitting manner. According to the preferred embodiment, the rotor shaft 8 and the gear input shaft 4 are arranged coaxially and rotate about a common axis of rotation 11.

[0031] The rotor shaft 8 carries a rotor 12, which has two rotor units spaced apart from each other, with only one rotor unit 14 shown in Fig. 1. The rotor units are fixed to one another by means of screw connections 16. A stator (not shown in Fig. 1) of the electric rotary machine 10 is arranged between the two rotor units. In the preferred embodiment shown in Fig. 1, the rotor 12, or the rotor unit 14 shown, is integrally formed with the rotor shaft 8. The rotor shaft 8 is furthermore designed as a hollow shaft and is coupled to a shaft journal 18 of the gearbox input shaft 4 of a connected gearbox (not shown) by means of the coupling unit 6. In particular, the gearbox can be a planetary gear unit, so that the gearbox input shaft 4 can also be referred to as a sun shaft. As shown in Fig. 1, the rotor 12 is supported by means of a current-insulating rotary bearing 20.The rotary bearing 20 is supported on its radial inner side by a motor support element 22, which in turn is fixedly arranged in a housing 24 of the electric rotary machine 10. Alternatively, the motor support element 22 can also be designed as an integral / one-piece component of the housing 24.

[0032] The axial degree of freedom of the rotary bearing 20 is blocked along an axial direction by means of a support element 26. The terms "radial" and "axial" always refer to the axis of rotation 11 of the electric rotary machine 10. The support element 26 has a rotationally symmetrical cross-section and is fixed to the motor support element 26 by means of a screw 28. On the axially opposite side, the rotary bearing 20 is fixed by means of a snap ring 30.

[0033] As shown in Fig. 1, the electric rotary machine 10 further comprises a grounding element 32, which, according to the preferred embodiment, is clamped against the rotor shaft 8 via the screw 28. For this purpose, the grounding element 32 is arranged in a cup-shaped receiving element 34, the circumferential rim of which rests against the rotor shaft 8. A helical spring 36 is also received in the receiving element 34, which presses the grounding element 32 against a ball 38 resting against the screw 28, thus clamping the grounding element 32 axially against the rotor shaft 8. The grounding element 32 thus forms a sliding contact on the rotor shaft 8, which is preferably implemented by means of brushes. The grounding element 32 can be designed in the form of a grounding ring or pin. The grounding element 32 can also be designed as a grounding pin or a grounding pin.

[0034] As explained above, the coupling unit 6 and the rotary bearing 20 are designed as current-insulating components. That is, the coupling unit 6 has at least one torque-transmitting insulating element. Preferably, the coupling unit 6 can be an Oldham or a Vulkollan coupling. In the preferred embodiment, the rotary bearing 20 is designed as a double-row ball bearing. To achieve the current-insulating effect, at least one component consisting of an inner ring 40, an outer ring 42, or a plurality of rolling elements 44 guided between the inner ring 40 and the outer ring 42 is made of a current-insulating material, such as ceramic, or has a coating of the current-insulating material. By providing the current-insulating components coupling unit 6 and rotary bearing 20, parasitic currents that could damage the rotary bearing 20 can be avoided. As shown in Fig.As can be seen in Figure 1, in the preferred embodiment the grounding element 32 is arranged radially adjacent to the coupling unit 6. This means that there is only a small distance in the radial direction between the grounding element 32 and the coupling unit 6. In particular, the grounding element 32 is arranged radially inside the coupling unit 6. This ensures targeted current dissipation.

[0035] List of reference signs

[0036] Geared motor unit

[0037] Gearbox input shaft

[0038] Clutch unit

[0039] Rotor shaft electric rotary machine

[0040] axis of rotation

[0041] rotor

[0042] Rotor unit

[0043] screw connection

[0044] corrugated cone

[0045] pivot bearing

[0046] Motor mounting element

[0047] Housing

[0048] Plant element

[0049] screw

[0050] snap ring

[0051] grounding element

[0052] Recording element

[0053] coil spring

[0054] Bullet

[0055] inner ring

[0056] outer ring

[0057] rolling elements

Claims

Patent claims 1. Electric rotary machine (10) with a rotor (12) arranged on a rotor shaft (8), which is at least partially supported in the radial direction by means of a rotary bearing (20), wherein the rotor shaft (8) carries a coupling unit (6) which is configured for coupling with a gearbox input shaft (4), characterized in that the rotary bearing (20) is a current-insulating rotary bearing (20) and the coupling unit (6) is a current-insulating coupling unit (6).

2. Electric rotary machine (10) according to claim 1 , characterized in that one axial degree of freedom of the rotary bearing (20) is blocked along an axial direction by means of a support element (26).

3. Electric rotary machine (10) according to claim 1 or 2, characterized in that the rotary bearing (20) is a rolling bearing with an inner ring (40), an outer ring (42) and a plurality of rolling elements (44) guided between the inner ring (40) and the outer ring (42), wherein the inner ring (40) and / or the outer ring (42) has a current-insulating coating, preferably a ceramic coating, and / or wherein the plurality of rolling elements (44) are made of a current-insulating material, preferably ceramic.

4. Electric rotary machine (10) according to one of the preceding claims 1 to 3, characterized in that the coupling unit (6) has at least one torque-transmitting insulating element.

5. Electric rotary machine (10) according to one of the preceding claims 1 to 4, further characterized by at least one grounding element (32) attached to one of the two components mounting element (26) and rotor shaft (8) is fixed and forms a sliding contact and / or a capacitive transmission element on the other component.

6. Electric rotary machine (10) according to claim 5, characterized in that the grounding element (32) and the coupling unit (6) are arranged adjacent to each other in a radial direction.

7. Electric rotary machine (10) according to claim 5 or 6, characterized in that the grounding element (32), preferably contactless, is arranged in a radial direction inside the gearbox input shaft (4).

8. Electric rotary machine (10) according to one of the preceding claims 1 to 7, characterized in that the electric rotary machine (10) is an axial flux machine, the rotor (12) of which has two axially spaced rotor units (14) from each other, wherein the rotor shaft (8) is an integral part of one of the two rotor units (14) and the two rotor units (14) are firmly connected to each other by means of screw connections (16).

9. Electric drive system comprising several electric rotary machines (10), at least one of which is an electric rotary machine (10) designed according to any one of claims 1 to 8, wherein the axes of rotation (11) of the rotor shafts (8) of the electric rotary machines (10) are arranged on an ideal axis or an output shaft coupled to the rotor shaft (8) of the electric rotary machine (10) runs parallel to the axis of the rotor shaft (8) of the electric rotary machine (10).

10. Geared motor unit (2), comprising at least one electric rotary machine (10) according to any one of claims 1 to 8 or an electric drive system according to claim 9, and a transmission whose transmission input shaft (4) is connected with the rotor shaft (8) of the electric rotary machine (10) is coupled or can be coupled via the coupling unit (6).

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