Oil-discharged electric motor with rolling bearing for a motor vehicle

Abstract

The invention relates to an electric motor (10) for an electrically operable axle of an electric vehicle, the motor comprising: a shaft (12) with an axis of rotation (D), at least one bearing (14), wherein the shaft is rotatably mounted via the at least one bearing, at least one end shield (16), at least one bearing ring (18), the at least one bearing ring being arranged coaxially with the axis of rotation (D), the at least one bearing being connected to the end shield via the bearing ring, and the bearing ring having on the outside at least one longitudinal recess (20a, 20b) for fluid drainage. The invention also relates to an electrically operable axle with an electric motor for a motor vehicle. A reliable operating, cost-effective, simple and modularly compatible electric motor is thus provided.

Description

Technical Field

[0001] The invention relates to an electric machine for an electrically operable axle of a motor vehicle. The electric machine comprises a shaft which is rotatably mounted by means of at least one rolling bearing. Background Art

[0002] The field of application of the invention extends primarily to electric machines with rolling bearings installed in at least partially or fully electrically driven motor vehicles. An at least partially or fully electrically driven motor vehicle is to be understood as a mild hybrid vehicle, a full hybrid vehicle, a plug-in hybrid vehicle or an electric vehicle. An electric machine is to be understood as an electric motor having a stator and a rotor.

[0003] The invention also relates to an electrically operable axle for a motor vehicle having an electric machine.

[0004] Especially in the field of electromobility, requirements are being imposed due to the changed use cases compared to conventional drive concepts. With electric vehicles, the demands on existing storage devices are increasing, for example due to the increase in car sharing, resulting in longer use times. Both oil- and grease-lubricated rolling bearings are important here. The electric machine can be integrated into an electric axle, i.e. an electrically operated axle. In the case of integration into a transmission, the electric machine is an electrified transmission.

[0005] However, in previously known electric machines, the oil collects as a fluid in the bearing area. Dirt, particles and wear products can collect together with the oil. This can damage the bearings. In addition, higher temperatures are present in this area, which can also lead to damage. In addition, due to the high degree of integration of motor vehicle components, the installation space for all components and construction solutions is severely limited. Therefore, a solution that is economical in terms of installation space is advantageous.

[0006] Other boundary conditions are also critical, such as high speeds, high powers and high operating temperatures. Another factor to consider is the diversity of applications, which differ only in the length of the rotor of the motor or in the gear interface. These boundary conditions require flexible, especially modularly compatible and cost-effective solutions.

[0007] In particular, examples of disadvantages to be overcome are collection points for dirt, particles and wear, high temperatures in storage areas, high costs for replacing bearings and laborious repairs of bearings. Summary of the invention

[0008] It is therefore an object of the present invention to produce an improved electric machine and an improved electric vehicle axle having an electric machine.

[0009] According to the invention, this object is achieved by an electric machine and a tram axle having the features of the independent claims. Preferred embodiments of the invention are described in the dependent claims and in the following description, each of which can represent an aspect of the invention either alone or in combination.

[0010] The invention therefore relates to an electric machine for an electrically operable axle of a motor vehicle, the electric machine comprising: a shaft having an axis of rotation; at least one bearing, wherein the shaft is arranged to be rotatably mounted by means of the at least one bearing; at least one end shield; at least one bearing ring, wherein the at least one bearing ring is coaxial with the axis of rotation, wherein the at least one bearing is connected to the end shield via the bearing ring and wherein the bearing ring has on its exterior at least one longitudinal recess for fluid drainage.

[0011] The invention also relates to an electrically operable axle for a motor vehicle having an electric machine as described above.

[0012] The drainage or discharge of fluid, in particular oil, from the area of ​​the bearing in the electric machine, i.e. the bearing area, can be achieved through a recess, such as a groove or a channel, in the bearing ring. Regardless of the position of the bearing ring, the fluid can flow, for example, through the recess in the bearing ring into a collecting recess in the end shield. The bearing ring can be positioned on the end shield by means of a centering surface. The fluid can flow out through the holes in the end shield and therefore not collect in the area of ​​the bearing. In particular, the solution according to the invention enables a cost-effective solution to be achieved, which is compact in terms of installation space and can be used to drain fluid, in particular oil, from the bearing area. The bearing is preferably a rolling bearing, particularly preferably a ball bearing. In addition, the solution according to the invention enables a high degree of flexibility and can be installed in many different electric machines, which differ in terms of effective length or power and / or transmission interface. Reliable operation of the electric machine is also advantageous.

[0013] Electric machines are machines used in electrical energy technology and represent a form of energy converter. A distinction is made between rotating electric machines, which include various types of electric motors and generators, and stationary electric machines including transformers. What all electric machines have in common is that they have a magnetic circuit in their structure, which is important for the function of the electric machine.

[0014] Electric machines use the properties of electromagnetic interactions and are based on electromagnetic induction and magneto-force effects which are described by the Lorentz force and for certain machine types by the reluctance force.

[0015] For historical reasons, transformers belong to a group of stationary or static electrical machines, especially transformers used in the field of power engineering, such as power transformers. In the case of stationary electrical machines, the magnetic effect plays only a secondary or undesirable role, since no movement is performed and the function of the transformer is to transform the alternating voltage between different high voltage levels. In the larger field of rotating electrical machines, which are specifically shown below - these rotating electrical machines are characterized by a large number of different designs and application fields - the magnetic effect plays a central role. The magnetic effect is used to convert electrical power into mechanical power on the shaft. If the electrical power is converted into mechanical power, the electrical machine is called an electric motor, if the mechanical power is converted into electrical power in the opposite direction, the electrical machine is called a generator. Some electrical machine types can operate both as motors and generators; the specific function is determined by the operating range of the machine.

[0016] The electric motor has coils of different arrangements, through which the current flows. The resulting magnetic flux is guided in a targeted manner in the core, which is also called the magnetic circuit. The core is made of a material that can conduct the magnetic flux, such as a layered electrical metal sheet. The layering together with the insulation of one side of the metal sheet part serves to suppress undesired eddy currents. In a rotating machine, the stator and the rotor - also known as the armature in some machines - are essential components. The forces generated in each of the two magnetic fields cause a targeted, one-time or continuous movement of the machine parts against each other.

[0017] For electrical insulation of the parts through which the current flows from each other and from the external environment, the electric machine has insulating areas. Mechanical support structures and preferably bearings for guiding the moving parts serve to mechanically stabilize the machine.

[0018] In an electric machine, the bearing shields are usually the rear and front covers of the housing, which protect the inside of the machine from contact with the bearings at the ends of the shafts of the armature and accommodate the bearings. The bearing shields are precisely fitted in the stator housing to ensure that the air gap between the stator and the armature is as uniform as possible. When the end shields are removed for repair or maintenance work, the installation position can thus be marked so that the end shields can be reassembled in exactly the same position during reassembly. The A-shaped end shields preferably represent the output side and carry the fixed bearings, the B-shaped end shields are preferably arranged on the fan side, wherein the bearings are carried via sliding seats so that thermal expansion of the armature can be compensated.

[0019] The bearing can be a rolling bearing, particularly preferably a ball bearing. The rolling bearing comprises an inner ring, an outer ring and a roller body arranged radially between the inner ring and the outer ring.

[0020] The bearing ring is preferably manufactured by stamping, turning from a component, machining, made from casting, or using a similar manufacturing process.

[0021] According to a preferred embodiment of the invention, it is provided that the at least one longitudinal recess is arranged on the outer circumference of the bearing ring in a manner extending parallel to the axis of rotation. This creates a storage and flow space for accumulating fluid, wherein the fluid may be contaminated by abrasives. This enables a component-friendly solution to be realized in a simple and inexpensive manner.

[0022] According to a preferred embodiment of the invention, it is provided that the at least one longitudinal recess is arranged on the end face of the bearing ring in such a way that it extends perpendicularly to the axis of rotation. This creates a storage and flow space for accumulating fluid, wherein the fluid may be contaminated by abrasives. This enables a component-friendly solution to be realized in a simple and inexpensive manner.

[0023] According to a preferred embodiment of the invention, it is provided that at least one longitudinal recess parallel to the axis of rotation and at least one longitudinal recess perpendicular to the axis of rotation are arranged in alignment with each other, wherein the bearing ring preferably has a plurality of longitudinal recesses in the circumferential direction, which are particularly evenly distributed over the circumference of the bearing ring. Arranged in alignment with each other in the context of the invention means that at least two longitudinal recesses arranged in this way each form a connection for fluid removal. Fluid can thus be removed along and through the axis of rotation.

[0024] According to a preferred embodiment of the invention, it is provided that the bearing ring is a separate component or an outer ring of the bearing. The design as a separate component enables the use of inexpensive standard bearings. The design as a separate component enables a compact design.

[0025] According to a preferred embodiment of the invention, it is provided that the bearing ring is positioned on the end shield via a centering surface. This enables simple assembly and reliable fluid drainage.

[0026] According to a preferred embodiment of the invention, it is provided that the end shield has at least one circumferentially extending collecting recess for receiving the fluid. The at least one circumferentially extending collecting recess is arranged in particular in a region in which the fluid collects by gravity and can flow away from the region without external influences. Particularly preferably, the fluid enters the collecting recess of the end shield as directly as possible from the at least one longitudinal recess of the bearing ring.

[0027] According to a preferred embodiment of the invention, it is provided that the end shield has at least one radially extending radial recess, wherein the at least one radial recess preferably has a vertical main extension axis. A vertical main extension axis is to be understood as a main extension axis that enables the fluid to flow away by gravity. Particularly preferably, the fluid reaches the radial recess of the end shield as directly as possible from the collecting recess in the end shield. In particular, the radial recess guides the fluid out of the motor. For this purpose, the radial recess can guide the fluid out of the motor vertically or laterally. This configuration enables the discharge of the fluid from the motor to be cost-effective, compact and at the same time reliable.

[0028] According to a preferred embodiment of the invention, it is provided that the at least one longitudinal recess, the at least one collecting recess and the at least one radial recess form a fluid channel for conducting the fluid out of the motor. Preferably, the longitudinal recess parallel to the axis of rotation and the longitudinal recess radial to the axis of rotation can be regarded as a common longitudinal recess. This configuration enables the discharge of the fluid from the motor to be cost-effective, compact and at the same time reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In the following, the present invention is described by way of example using preferred exemplary embodiments with reference to the accompanying drawings, wherein the features shown below can represent an aspect of the present invention both individually and in combination. In the drawings:

[0030] Figure 1 : shows a motor according to the prior art,

[0031] Figure 2 : shows a motor according to a preferred embodiment of the present invention,

[0032] Figure 3 :shows the Figure 2 The end shield of the motor,

[0033] Figure 4 : A first perspective view shows a method for Figure 2 The bearing ring of the motor, and

[0034] Figure 5 :The second stereogram shows Figure 4 bearing ring. DETAILED DESCRIPTION

[0035] Figure 1 An electric machine 10 according to the prior art is shown for an electrically operable axle of a motor vehicle.

[0036] Figure 2 An electric machine 10 of a preferred design for an electrically operable axle of a motor vehicle is shown.

[0037] include:

[0038] - a shaft 12 having an axis of rotation D,

[0039] at least one bearing 14, wherein the shaft 12 is rotatably mounted by means of the at least one bearing 14,

[0040] - at least one end shield 16,

[0041] at least one bearing ring 18 arranged coaxially with the axis of rotation D, wherein the at least one bearing 14 is connected to the end shield 16 via the bearing ring 18 and wherein the bearing ring 18 has on its outside a plurality of longitudinal recesses 20a, 20b for fluid drainage.

[0042] Through the numerous longitudinal recesses 20a, 20b in the bearing ring 18, fluid, in particular oil, can flow into the collecting recesses 22 arranged in the end shield 16. The fluid is thus collected in the collecting recesses 22. This is independent of the position of the bearing ring 18. The bearing ring 18 can be positioned on the end shield 16 by means of the centering surface. The fluid can then flow out through at least one radial recess 24 in the end shield 16 and no longer collect in the bearing area 26.

[0043] For example, the illustrated end shroud 16 is a B-shaped end shroud. The B-shaped end shroud is preferably arranged on the fan side of the electric machine 10.

[0044] According to a preferred embodiment of the invention, it is provided that a plurality of longitudinal recesses 20a extending parallel to the rotation axis D are arranged on the outer periphery of the bearing ring 18. Figure 2 , Figure 4 and Figure 5 Seen in.

[0045] According to a preferred embodiment of the invention, it is provided that a plurality of longitudinal recesses 20b extending perpendicularly to the axis of rotation D are arranged on the end face of the bearing ring 18. Figure 2 , Figure 4 and Figure 5 Seen in.

[0046] According to a preferred embodiment of the invention, it is provided that a plurality of longitudinal recesses 20a are arranged parallel to the rotation axis D and a plurality of longitudinal recesses 20b are arranged perpendicular to the rotation axis D, the plurality of longitudinal recesses parallel to the rotation axis and the plurality of longitudinal recesses perpendicular to the rotation axis being aligned with each other. The longitudinal recesses 20a, 20b are particularly evenly distributed on the circumference of the bearing ring 18. This can be achieved in Figure 4 and Figure 5 Seen in.

[0047] According to a preferred embodiment of the invention, it is provided that the bearing ring 18 is a separate component. Figure 2 , Figure 4 and Figure 5 Seen in.

[0048] According to a preferred embodiment of the invention, it is provided that the bearing ring 18 is positioned on the end shield 16 via the centering surface 21. This can be seen from Figure 2 , Figure 3 , Figure 4 and Figure 5 See.

[0049] According to a preferred embodiment of the invention, it is provided that the end shield 16 has at least one circumferentially extending collecting recess 22 for receiving the fluid. Figure 2 and Figure 3 Seen in.

[0050] According to a preferred embodiment of the invention, it is provided that the end shield 16 has at least one radially extending radial recess 24, wherein the at least one radial recess 24 preferably has a vertical main extension axis. Figure 2 and Figure 3 Seen in.

[0051] According to a preferred embodiment of the invention, it is provided that the at least one longitudinal recess 20a, 20b, the at least one collecting recess 22 and the at least one radial recess 24 form a fluid channel for guiding the fluid out of the electric machine 10. This can be achieved from Figure 2 , Figure 3 , Figure 4 and Figure 5 See.

[0052] Description of Reference Numerals

[0053] 10 Motor 12 Shaft 14 Bearing 16 End shield 18 Bearing ring 20a Longitudinal recess parallel to the rotation axis 20b Longitudinal recess radial to the rotation axis 21 Centering surface 22 Collecting recess 24 Radial recess 26 Bearing area D Rotation axis of shaft.

Claims

1. An electric machine (10) for an electrically operable axle of a motor vehicle, the electric machine comprising: - a shaft (12) having an axis of rotation (D), - at least one bearing (14), via which the shaft (12) is rotatably mounted, - at least one end shield (16), - at least one bearing ring (18), at least one of which is arranged coaxially with the axis of rotation (D), via which the at least one bearing (14) is connected to the end shield (16), and which has on the outside at least one longitudinal recess (20a, 20b) for fluid drainage; wherein the at least one longitudinal recess (20a) is arranged on the outer periphery of the bearing ring (18) in a manner extending parallel to the rotation axis (D); and the at least one longitudinal recess (20b) is arranged on the end face of the bearing ring (18) in a manner extending perpendicular to the rotation axis (D); The end shield (16) has at least one radial recess (24) extending radially.

2. The electric machine (10) according to claim 1, characterized in that At least one longitudinal recess (20a) parallel to the rotation axis (D) and at least one longitudinal recess (20b) perpendicular to the rotation axis (D) are arranged to be aligned with each other, wherein the bearing ring (18) has a plurality of longitudinal recesses (20a, 20b) in the circumferential direction, and the plurality of longitudinal recesses are evenly distributed on the circumference of the bearing ring (18).

3. The electric machine (10) according to claim 2, characterized in that The bearing ring (18) is a separate component or an outer ring of the bearing (14).

4. The electric machine (10) according to claim 3, characterized in that The bearing ring (18) is positioned on the end shield (16) via a centering surface (21).

5. The electric machine (10) according to claim 4, characterized in that The end shield (16) has at least one circumferentially extending collecting recess (22) for receiving fluid.

6. The electric machine (10) according to claim 5, characterized in that The at least one radial recess (24) has a vertical main axis of extension.

7. The electric machine (10) according to claim 6, characterized in that The at least one longitudinal recess (20a, 20b), the at least one collecting recess (22) and the at least one radial recess (24) form a fluid channel for guiding fluid out of the motor (10).

8. An electrically operable axle for a motor vehicle having an electric motor (10), characterized in that An electric machine (10) is provided according to at least one of the preceding claims.

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