CN112104116A

CN112104116A - Stator assembly, motor and electric drive axle system

Info

Publication number: CN112104116A
Application number: CN202010914455.XA
Authority: CN
Inventors: 欧阳鹏; 刘磊; 夏小俊
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2020-09-03
Filing date: 2020-09-03
Publication date: 2020-12-18

Abstract

The invention relates to a stator assembly, a motor and an electric drive axle system. The stator assembly comprises a stator core (1) which is annular and is formed with a plurality of coolant axial channels (6) which are distributed in the circumferential direction and which extend through two axial end faces of the stator core, and two guide rings (2, 3) which each provide a plurality of coolant circumferential channels (7, 8) which are distributed in the circumferential direction and which extend in the circumferential direction as a whole, wherein the two guide rings are arranged concentrically with the stator core and each lie against two axial end faces of the stator core in such a way that the coolant axial channels each communicate with the coolant circumferential channels of the respective guide ring with their axial ends and form at least one coolant channel which runs in a meandering manner in the circumferential direction as a whole. The electric machine includes the stator assembly described above and the electric drive axle system includes the electric machine described above.

Description

Stator assembly, motor and electric drive axle system

Technical Field

The invention relates to the technical field of vehicles. The invention relates specifically to a stator assembly with a cooling structure. The invention also relates to an electric machine comprising the stator assembly and an electric drive axle system comprising the electric machine.

Background

Electric motors are widely used in vehicles such as vehicles. The electric machine may be used in particular for an electric drive axle system of, for example, an electric only vehicle or a hybrid vehicle, in particular an electric only vehicle or a hybrid vehicle. With the increasing demand for smaller and lighter motors, the demand for the index of the power density of the motor is increasing, and the power limit capability is limited by the temperature rise limit of the motor, so that it is very necessary to improve the cooling and heat dissipation capability of the motor.

There are currently a large number of cooling solutions for electric machines.

An electric machine comprising a stator and a rotor each having a cooling circuit is disclosed, for example, in US 9.287,754B 2. In this solution, the cooling circulation circuit of the stator is realized by a cooling water jacket disposed radially outside the stator. A further example is disclosed in chinese patent application CN 109873517 a for a cooling structure of an electric machine. The structure includes a motor housing having an inner wall, an outer wall, and a plurality of cooling fins provided on the inner wall, and forming a cooling channel between the inner wall and the outer wall. However, in both of the above cooling solutions, the heat inside the motor needs to be conducted to the radial outside through the layer of material, and then carried away by the water channel. In this case, the windings of the motor and the heat source such as the magnetic steel cannot be directly cooled, and the cooling structure does not extend even to the end winding, resulting in heat accumulation and limited cooling efficiency.

Also, for example, in chinese patent document CN 102224658B, a rotary electric machine is disclosed, which includes two coil end covers and a plurality of connecting wires, wherein the two coil end covers respectively surround two winding end portions of the rotary electric machine and respectively form a cooling oil passage, and wherein the plurality of connecting wires are provided in the cooling oil passage, thereby cooling the winding end portions of the electric machine. However, in this cooling scheme, the outer peripheral surface of the stator core is not provided with a cooling structure, and heat exchange cannot be performed there. This results in, on the one hand, a lower cooling efficiency and, on the other hand, may affect the insulation of the system when the temperature of the stator core increases.

Disclosure of Invention

The object of the present invention is therefore to provide an electric machine which can be used in electric vehicles or hybrid vehicles and which has an improved cooling structure of the electric machine, as a result of which the cooling efficiency can be increased.

The stator assembly comprises a stator core and two guide rings, wherein the stator core is annular and is configured with a plurality of coolant axial channels distributed in the circumferential direction and penetrating through two axial end faces of the stator core, wherein the two guide rings respectively provide a plurality of coolant circumferential channels distributed in the circumferential direction and extending along the circumferential direction in an integral manner, wherein the two guide rings are arranged concentrically with respect to the stator core and are respectively in contact with the two axial end faces of the stator core in such a way that the coolant axial channels respectively communicate with the coolant circumferential channels of the respective guide rings at both axial ends thereof and form at least one coolant passage extending in a meandering manner in the circumferential direction in general.

The stator assembly generally comprises a stator and a cooling unit for the stator, in particular a coolant passage. The stator includes an annular stator core and windings. The rotational axis of the electric machine or of its rotor is in this case coaxial with the center axis of the stator or of the stator core. In the present context, the terms "axial", "radial" and "circumferential" refer to the abovementioned median axis, unless otherwise indicated. Specifically, "axial" is a direction of the central axis or a direction parallel to the central axis. "radial" is the direction perpendicular to and intersecting the central axis. "circumferential direction" is the direction around the central axis.

The coolant channel here forms part of a cooling circuit of a thermal management module for the electric machine. Coolant is provided by other means in the thermal management module and flows through the coolant passages in the stator assembly at a desired flow rate. The coolant can thereby exchange heat with a heat source in the electric machine, in particular in the stator, during the flow through the coolant passage, and the heat exchanged can be removed from the stator assembly region as the coolant is discharged, in particular from the coolant passage.

A coolant passage collectively composed of a plurality of coolant axial passages and a plurality of coolant circumferential passages extends meanderingly in the circumferential direction of the stator assembly as a whole. By "meandering" is here understood an S-shaped or serpentine distribution of the coolant passages in the circumferential direction of the stator assembly.

For convenience of illustration, each coolant circumferential channel of one of the guide rings may be exemplarily labeled as a first circumferential channel, a third circumferential channel, and so on, in sequence along one circumferential direction; the coolant circumferential channels of the other guide ring are sequentially marked as a second circumferential channel and a fourth circumferential channel along the same circumferential direction, and the like; each coolant axial passage of the stator core is labeled, in order, along the same circumferential direction, as a first axial passage, a second axial passage, a third axial passage, and so on. The ordinal numbers mentioned herein are only used to distinguish the channels, and do not limit the number of the channels of each type.

In a possible embodiment, at least in the middle section of each coolant channel, i.e. the section of the coolant channel excluding the coolant inlet and the coolant outlet region, the first circumferential channel, the first axial channel, the second circumferential channel, the second axial channel, the third circumferential channel, the third axial channel, the fourth circumferential channel can be connected end to end in succession and possibly further channels can be connected in the same way or in the same way. This makes it possible to simply achieve a meandering of the coolant channel in the circumferential direction.

Within the scope of this document, the coolant axial channel may communicate with two respective coolant circumferential channels belonging to the two guide rings, i.e. with coolant circumferential channels at both axial ends of the coolant axial channel, but it is not limited herein that the coolant axial channel must extend strictly in the axial direction.

Within the scope of this document, the coolant circumferential channel extends in its entirety in the circumferential direction, but it is not limited that each section of the coolant circumferential channel extends strictly in the circumferential direction.

Within the scope of this document, the shaping of the cross-sections of the coolant passages, i.e. the coolant axial channels and the coolant circumferential channels, is not restricted. The cross-sectional shapes and sizes of the axial coolant channels and the circumferential coolant channels may be designed according to the overall configuration of the thermal management module.

Here, the coolant is a fluid. Optionally, the coolant is a liquid. Optionally, the coolant is a gas. Preferably, the coolant is an insulating fluid. It is particularly preferred that the coolant is a fluid that is magnetically non-conductive and electrically non-conductive, whereby the coolant does not influence the magnetic circuit of the electric machine and can directly cool the heat source within the electric machine. The coolant may be, for example, cooling oil or air, in particular.

Preferably, the stator assembly includes at least two coolant passages, whereby cooling efficiency can be improved. Advantageously, the individual coolant passages may be distributed in different regions of the stator assembly in the circumferential direction. Advantageously, the individual coolant passages can also be arranged one above the other or nested one inside the other in the same region of the stator assembly in the circumferential direction.

In this way, by means of the coolant axial channels distributed in the stator core, the coolant can be particularly effectively heat-exchanged with the stator core and thus heat-distributed in the sub-outer circumferential region. At the same time, the coolant can exchange heat particularly effectively with the winding sections of the stator, in particular the end winding sections, by means of the coolant circumferential channels provided by the two guide rings, as a result of which the heat of the end windings can be dissipated. In other words, through the cooling structure of the stator assembly provided by the invention, the stator core and the end winding can be directly cooled, the cooling efficiency is improved, and the power density of the motor is favorably improved. Furthermore, the cooling structure of the stator assembly provided herein also reduces the particularly radial dimensions of the electrical machine compared to prior art solutions providing cooling jackets.

In a preferred embodiment, the guide ring is made of an insulating material, in particular a material that is magnetically impermeable and electrically non-conductive. The guide ring is made of plastic or resin, for example. In this case, the arrangement of the guide ring does not affect the magnetic circuit of the electric machine, in particular of the stator assembly.

Alternatively, the guide ring can also be made of a metallic material. Particularly in the design scheme that the distance between the guide ring and the end winding is large, the advantages of the metal material in the aspects of strength and heat conductivity can be fully utilized under the condition that the influence on the magnetic circuit of the stator assembly is ensured within an acceptable range.

In a preferred embodiment, the guide ring has a plurality of circumferentially distributed arcuate grooves formed in its axial end face, wherein the arcuate grooves together with the axial end face of the stator core form a circumferential coolant channel. The arc-shaped groove is closed by an axial end face of the stator core, so that a coolant circumferential channel is formed. The coolant circumferential channel can thereby be realized in a simple and cost-effective manner.

In a preferred embodiment, the stator core and the two guide rings are fixedly connected. The fixed connection can be realized here by a material connection, a form-fitting connection and/or a press-fit connection. The respective connection of the two guide rings to the stator core can be realized by the same connection means or by different connection means. In this case, the stator assembly can be transported and assembled as a whole, which is advantageous for simplifying the process steps in the manufacturing process of the electric machine.

Alternatively, the stator core and the two guide rings can be placed against one another by means of other components in the electric machine. In this case, the required contact arrangement can be automatically formed by further components in the electric machine after the assembly of the electric machine has been completed, without the need for additional connecting structures between the stator core and the two guide rings, as a result of which the process steps in the production process can be simplified on the other hand.

In an advantageous embodiment, the guide ring bears sealingly against the stator core. For example, such a sealing abutment can be achieved if the guide ring and the stator core are adhesively sealed by means of a sealing compound. Alternatively, such sealing abutment can also be achieved by providing a seal between the guide ring and the stator core. Leakage of coolant can thereby be prevented, facilitating fluid dynamic control in the cooling circuit of the thermal management module.

Alternatively, the guide ring can also bear against the stator core in a non-sealing manner. In this case, a particularly insulating coolant, for example cooling oil, can flow out of the axial gap between the guide ring and the stator core and can flow onto the windings, in particular the end windings, as a result of which the windings can be cooled directly and the cooling efficiency can be increased.

In an advantageous embodiment, the guide ring is configured with a through-opening which extends through the coolant circumferential channel and the inner circumferential surface of the guide ring. Preferably, at least one guide ring is configured with the above-mentioned through hole. Preferably, the same guide ring is provided with a plurality of the above-mentioned through holes, which communicate with the inner peripheral surface of the guide ring and the same and/or different coolant circumferential channels, respectively. Advantageously, the through-hole is configured as a radial through-hole. Advantageously, the through-hole is arranged above the guide ring in the operating state of the electric machine. In this case, a particularly insulating coolant, for example cooling oil, can flow out of the through-opening and be sprayed onto the winding, in particular the end winding, as a result of which the winding can be cooled directly and the cooling efficiency can be increased.

In a preferred embodiment, the coolant axial channel is designed linearly and/or curved. In this case, the straight coolant axial channel is easy to produce. The curved coolant axial channels can advantageously increase the heat exchange area of the coolant channels in the region of the stator core, thereby increasing the cooling efficiency.

According to a preferred embodiment, the coolant channel has a coolant inlet and a coolant outlet, wherein the coolant inlet is arranged at the coolant axial channel and/or the coolant circumferential channel and the coolant outlet is arranged at the coolant axial channel and/or the coolant circumferential channel.

In this case, the stator assembly advantageously comprises at least two coolant passages, wherein the at least two coolant passages have a common coolant inlet and/or a common coolant outlet. In this case, the individual coolant passages form branches of a total coolant path. This makes it easy to arrange the pipes communicating with the coolant inlet and the coolant outlet, and also makes it possible to improve the cooling efficiency of the coolant passage by the plurality of branches.

The above technical problem is solved in another aspect of the present invention by an electric machine comprising a stator assembly having the above technical features. In addition, the motor further includes a rotor.

Preferably, the motor is configured as an inner rotor type motor. Preferably, the electric machine may constitute a traction motor for an electric machine of an electric-only vehicle or a hybrid vehicle. Here, the electric machine may advantageously be used as a motor or a generator depending on the vehicle driving state. Advantageously, the electric machine may form an electric machine for an electric drive axle system, for example a wheel hub motor or a wheel hub motor.

The above technical problem is solved in another aspect of the present invention by an electric drive axle system comprising an electric motor as described above. The electric drive axle system is especially configured in an electric machine of a pure electric vehicle or a hybrid vehicle.

Drawings

A preferred embodiment of the invention is schematically illustrated in the following with reference to the accompanying drawings. The attached drawings are as follows:

FIG. 1 is a schematic perspective view of a stator assembly in accordance with a preferred embodiment;

figure 2 is a schematic axial cross-sectional view of a stator assembly according to figure 1;

figure 3 is a front view of a guide ring of the stator assembly according to figure 1; and

fig. 4 is a perspective view of the guide ring according to fig. 3.

Detailed Description

Fig. 1 and 2 show a schematic perspective view and an axial cross-sectional view, respectively, of a stator assembly according to a preferred embodiment. The stator assembly forms part of a traction motor for an electric drive axle system. The electric drive axle system can be configured in particular in an electric machine of a purely electric vehicle or a hybrid vehicle.

As shown in fig. 1 and 2, the stator assembly includes a stator and a cooling unit for the stator. The stator includes a ring-shaped stator core 1 and windings 10. The stator core 1 is annular. The winding 10 is made of copper material. A not shown rotor of the traction motor may rotate radially inside the stator.

The cooling unit of the stator is designed here as a coolant channel for a thermal management module of the electric machine. The coolant channel is formed here by the stator core 1 and two guide rings, namely a first guide ring 2 and a second guide ring 3. Coolant is provided by other means in the thermal management module and flows through the coolant passages in the stator assembly at a desired flow rate. During flow through the coolant passages, the coolant may exchange heat with a heat source in the stator, and the exchanged heat may be expelled from the stator assembly area as the coolant is expelled. The coolant used in the present embodiment is cooling oil, which, by virtue of its non-magnetic and non-conductive properties, advantageously avoids influencing the magnetic circuit of the electric machine and allows direct cooling of the heat source within the electric machine.

The stator core 1 is configured with a plurality of coolant axial channels 6 distributed in the circumferential direction and penetrating both axial end faces of the stator core 1. The axial coolant channel 6 is configured in the present embodiment as a straight coolant channel extending in the axial direction. The coolant axial channel 6 can be of circular cross-sectional configuration. In further embodiments, the coolant axial channels 6 can be offset from cross sections which extend axially and/or extend in a curved manner and/or are configured with other shapes.

Fig. 3 and 4 show a front view and a perspective view, respectively, of the guide ring 2 of the stator assembly according to fig. 1. As can be seen in conjunction with fig. 3 and 4, the guide ring 2, i.e. the first guide ring, is configured with a plurality of arc-shaped grooves 7 distributed in the circumferential direction and extending overall in the circumferential direction. The second guide ring 3 (see fig. 1 and 2) can be constructed similarly to the first guide ring 2, the second guide ring 3 likewise being constructed with a plurality of circumferentially distributed, overall circumferentially extending, arc-shaped grooves 8. The guide rings 2, 3 are made of a magnetically non-conductive and electrically non-conductive material, for example plastic.

As can be seen from fig. 1 to 4, two guide rings 2, 3 are arranged concentrically with respect to the stator core 1 and are each adhesively sealed to the stator core 1 by means of a sealing compound. The two guide rings 2, 3 are thus placed against the two axial end faces of the stator core 1, so that the arc-shaped recess of the first guide ring 2 forms a coolant circumferential channel 7 with a square cross section in cooperation with the corresponding axial end face of the stator core 1, the arc-shaped recess of the second guide ring 3 forms a coolant circumferential channel 8 with a square cross section in cooperation with the corresponding axial end face of the stator core 1, and the coolant axial channel 6 is connected with its axial ends to the

coolant circumferential channels

7, 8, respectively. Here, a local S-shaped distribution of the coolant channels in the circumferential direction can be achieved by connecting the coolant circumferential channel 7, the coolant axial channel 6 and the coolant circumferential channel 8 in succession end to end. By continuously repeating such an end-to-end connection, a generally circumferentially meandering coolant passage can be realized.

The coolant passage has a coolant inlet 4 and a coolant outlet 5 distributed at both radial ends of the stator assembly. A coolant inlet 4 is configured at the stator core 1, the coolant inlet 4 radially communicating the outer circumferential surface of the stator core 1 and one of the coolant axial passages 6. A coolant outlet 5 is formed at the first guide ring 2, the coolant outlet 5 axially connecting an axial end face of the first guide ring 2 with a coolant circumferential channel 8 radially opposite the one coolant axial channel 6. In the present embodiment, two coolant passages are configured, distributed in two half-circumference regions of the stator assembly, having a common coolant inlet 4 and a common coolant outlet 5. The coolant enters the stator core 1 from the coolant inlet 4 and then flows zigzag in different circumferential directions through two coolant passages to the coolant outlet 5 radially opposite to the coolant inlet 4.

As a result, the coolant can be particularly effectively heat-exchanged with the stator core 1 and thus heat can be dissipated in the sub-outer circumferential region by means of the coolant axial channels 6 distributed in the stator core 1. At the same time, the coolant can be exchanged particularly effectively with the end winding parts by means of the

coolant circumferential channels

7, 8 provided by the two guide rings 2, 3, whereby the heat of the end winding can be dissipated. Therefore, the stator core 1 and the end winding 10 can be directly cooled, the cooling efficiency is improved, and the power density of the motor is favorably improved. Furthermore, the cooling structure of the stator assembly provided herein also reduces the particularly radial dimensions of the electrical machine compared to prior art solutions providing cooling jackets.

Furthermore, as shown in fig. 4, the guide ring 2 is configured with a plurality of through holes 9, the through holes 9 penetrating the coolant circumferential channel 7 and the inner circumferential surface of the guide ring 2 in the radial direction. In this case, the cooling oil can flow out of the through-holes 9 and be poured onto the windings 10, in particular the end windings, whereby the windings 10 can be cooled directly and the cooling efficiency can be increased.

Although possible embodiments have been described by way of example in the above description, it should be understood that numerous embodiment variations exist, still by way of combination of all technical features and embodiments that are known and that are obvious to a person skilled in the art. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. From the foregoing description, one of ordinary skill in the art will more particularly provide a technical guide to convert at least one exemplary embodiment, wherein various changes may be made, particularly in matters of function and structure of the components described, without departing from the scope of the following claims.

List of reference numerals

1 stator core

2 guide ring, first guide ring

3 guide ring, second guide ring

4 coolant inlet

5 coolant outlet

6 axial coolant channel

7 circumferential channels for coolant; coolant circumferential channel of first guide ring

8 circumferential channels of coolant; coolant circumferential channel of second guide ring

9 through hole

10 winding

Claims

1. A stator assembly for an electric machine, the stator assembly comprising:

-a stator core (1) which is annular and is configured with a plurality of coolant axial channels (6) distributed in the circumferential direction and penetrating both axial end faces of the stator core (1),

-two guide rings (2, 3) which respectively provide a plurality of circumferentially distributed and overall circumferentially extending coolant circumferential channels (7, 8),

wherein the two guide rings (2, 3) are arranged concentrically to the stator core (1) and are each in contact with two axial end faces of the stator core (1) in such a way that the coolant axial channels (6) each communicate with the coolant circumferential channels (7, 8) of the respective guide ring (2, 3) with their axial ends and form at least one coolant channel which runs in a meandering manner in the circumferential direction.

2. Stator assembly according to claim 1, characterized in that the guide rings (2, 3) at their axial end faces are configured with a plurality of circumferentially distributed arc-shaped grooves, wherein the arc-shaped grooves together with the axial end faces of the stator core (1) form the coolant circumferential channels (7, 8).

3. A stator assembly according to claim 1, characterized in that the stator core (1) and the two guide rings (2, 3) are fixedly connected.

4. Stator assembly according to claim 1, characterized in that the guide rings (2, 3) bear sealingly or non-sealingly against the stator core (1).

5. A stator assembly according to claim 1, characterized in that the guide ring (2) is configured with through holes (9), which through holes (9) penetrate the coolant circumferential channel (7) and the inner circumferential surface of the guide ring (2).

6. Stator assembly according to claim 1, characterized in that the coolant axial channels (6) are configured linearly and/or curved.

7. The stator assembly according to claim 1, characterized in that the coolant passage has a coolant inlet (4) and a coolant outlet (5), wherein the coolant inlet (4) is provided at the coolant axial channel (6) and/or the coolant circumferential channel (7, 8) and the coolant outlet (5) is provided at the coolant axial channel (6) and/or the coolant circumferential channel (7, 8).

8. The stator assembly according to claim 7, characterized in that the stator assembly comprises at least two coolant passages, wherein the at least two coolant passages have a common coolant inlet (4) and/or a common coolant outlet (5).

9. An electrical machine comprising a stator assembly according to any of claims 1-8.

10. An electric drive axle system comprising the electric machine of claim 9.