EP4449586A1 - Rotor for an electric machine having a cooling duct in a pole separator - Google Patents

Abstract

A rotor (1) for an electric machine (22), comprising: a rotor shaft (3), a laminated core (2) formed from stacked electrical laminations and having radially outwardly protruding laminated core protrusions (4), rotor windings (9) which are each wound around a laminated core protrusion (4), and a pole separator (10, 16, 19) which is arranged between two adjacent laminated core protrusions (4) and has a cooling duct (13, 17, 18, 20), which runs in the pole separator (10, 16, 19), for a coolant. In addition, a method for producing the rotor (1), an electric machine (22) having the rotor (1), and a vehicle (21) having the electric machine (22) are described.

Description

Rotor for an electrical machine with a cooling channel in a pole separator

The invention relates to a rotor for an electrical machine, an electrical machine with a rotor, a vehicle with an electrical machine and a method for producing a rotor.

The rotor has a rotor shaft and a laminated core formed from stacked electrical laminations and arranged on the rotor shaft. The rotor belongs together with a stator to an electrical machine.

Electric machines of this type are increasingly being used in electrically powered vehicles and hybrid vehicles, primarily as an electric motor for driving a wheel or an axle of such a vehicle.

Such an electric motor is usually mechanically coupled to a gear for speed adjustment. In addition, the electric motor is usually electrically coupled to an inverter, which generates an AC voltage for the operation of the electric motor, for example a polyphase AC voltage, from a DC voltage supplied by a battery.

It is also possible to operate an electric machine with such a rotor as a generator for recuperating kinetic energy of a vehicle. For this purpose, the kinetic energy is first converted into electrical energy and then into chemical energy from a vehicle battery.

In a certain type of electrically excited synchronous motor (EESM), the rotor has rotor windings which are supplied with direct current in order to generate an exciting magnetic field. If a rotating field is generated with the stator windings of an associated stator, this causes a force to act on the rotor, so that it rotates synchronously with the rotating field of the stator. However, the rotor windings are heated up considerably in the process, so that cooling is required. The cooling can take place, for example, by spraying coolant onto the axial sides of the rotor. However, this type of cooling only works superficially and is therefore not very effective.

The invention is therefore based on the object of specifying a rotor for an electrical machine which can be better cooled during operation of the electrical machine.

To solve this problem, a rotor with the features of claim 1 is provided.

The rotor according to the invention comprises a laminated core which is arranged on a rotor shaft and is formed from stacked electrical laminations, with radially outwardly protruding projections, rotor windings which are each wound around a projection of the laminated core (laminated core projection), and a pole separator arranged between two adjacent projections of the laminated core, in which a cooling channel for a coolant runs.

The invention is based on the finding that improved cooling can be achieved by supplying the coolant to the rotor windings via a cooling channel located in a pole separator. The coolant can flow along the rotor windings in the pole separator, so that the heat generated during operation of the electrical machine is dissipated. In comparison to a conventional rotor, in which only coolant is sprayed onto the axial sides, the rotor according to the invention can be cooled significantly better and more homogeneously.

Furthermore, a multifunctional component is created with the pole separator, with which the rotor is mechanically stabilized, protected against environmental influences and cooled. The electrical machine can be, for example, an electrically excited synchronous motor (EESM).

Optionally, the rotor has a first end plate, which is arranged at one axial end of the laminated core and a second end plate, which is arranged at the opposite axial end of the laminated core. The two end plates are used to hold the electrical laminations of the laminated core together and each have end plate projections that protrude radially outwards and that can be arranged in particular along the circumference of an end plate. The end plate projections are also referred to as "plate extensions" and serve, among other things, to hold the rotor windings in a certain position.

The laminated core projections of the laminated core are also referred to as "teeth" and can be arranged in particular along the circumference of the laminated core. In addition to a core stub, a rotor winding may be wound about an endplate stub of the first endplate and an axially opposite endplate stub of the second endplate, between which the core stub extends axially.

The cooling channel preferably runs from an axial side of the laminated core to an opposite axial side of the laminated core, for example straight and in the axial direction. Accordingly, the rotor windings can be cooled over their entire axial length. Thanks to the cooling, the temperature of the rotor can be kept below a specified limit value even during continuous operation at high power.

In the rotor according to the invention, it can be provided that the pole separator has an inner section, which is arranged between the two rotor windings, and an outer section, which is arranged radially outside of the two rotor windings. The rotor windings in particular can be mechanically stabilized and cooled with the inner section. Since the rotor windings are preferably made of coated copper wire, good heat conduction and heat dissipation via the pole separator is guaranteed. In particular, the ends of the laminated core projections can be mechanically stabilized and cooled with the outer section.

The pole separator can be manufactured inexpensively from a plastic material using an injection molding process. Alternatively, the pole separator can also be produced from a metal alloy, for example from an aluminum alloy, by extrusion.

Within the scope of the invention, it is preferred that the inner section of the pole separator is embedded in a casting compound with which the two rotor windings are cast. This stabilizes the rotor windings and improves heat transfer from the rotor windings to the pole separator.

In the rotor according to the invention, the cooling channel can run in the inner section of the pole separator and/or the outer section of the pole separator. The size and position of the cooling channel can thus be adapted to the respective cooling requirements and the space available.

In the case of low cooling requirements, it may be sufficient if the cooling duct is located in the inner section of the pole separator. If there is a greater need for cooling, the cooling channel can extend from the inner section into the outer section.

An embodiment of the invention provides that the cooling channel has a circular cross section. Such a cooling channel is characterized by low flow losses caused by friction. According to an alternative embodiment, the cooling channel can have a Y-shaped cross section. Such a cooling channel can be optimally arranged in a pole separator, which has an inner section, which is arranged between two adjacent rotor windings, and an outer section, which is arranged radially outside of the two Rotor windings is arranged having. In this case, the Y-shaped cooling channel or its cross section can extend from the inner section to the outer section. As an alternative to the cross-sectional shapes mentioned, the cooling channel can also have a rectangular, square, triangular, trapezoidal, hexagonal or elliptical cross-section. Basically, a larger cross-section allows a larger amount of heat to be dissipated.

A very particularly preferred embodiment of the invention provides that the cooling channel opens into an end cap of the rotor. The end cap can be arranged on an axial side of the laminated core, in particular covering an end cap positioned there. A second end cap can also be located on the opposite axial side of the cooling channel, in which the cooling channel also opens and which optionally covers a second end cap.

The end caps may seal the inside of the rotor to the outside and each have a passage opening for coolant, one serving as an inlet and the other serving as an outlet. An associated nozzle for coolant can be arranged in a housing of the electrical machine, with which coolant can be sprayed into the inlet. Alternatively, a connection for an external coolant line can also be integrated in an end cap.

In order to improve the cooling effect, the pole separator of the rotor according to the invention can have a number of cooling channels. This allows a larger amount of coolant to flow through the pole separator. Furthermore, the stability of the pole separator can be increased with several cooling channels. The cooling channels can be arranged one behind the other in the radial direction. As an alternative to this, the cooling channels can be arranged one behind the other in the circumferential direction, for example in the intermediate space formed between two rotor windings. However, it is also possible for a plurality of cooling ducts to be arranged one behind the other in the radial direction in the pole separator and for a plurality of cooling ducts to be additionally arranged one behind the other in the circumferential direction. For example, you can the former in the inner section and the latter in the outer section of the pole separator.

In a further embodiment of the invention, the rotor has a plurality of pole separators of the type described. The pole separators are each arranged between two (other) adjacent laminated core projections of the laminated core. The pole separators improve the cooling of the rotor, increase its stability and simplify the casting of the gaps between adjacent rotor windings with casting compound. The number of pole separators can correspond to or deviate from the number of poles (number of poles) of the rotor.

The coolant can be supplied to the cooling channels in various ways. For example, the rotor shaft can have one or more bores through which the coolant flows from a central cooling duct running in the rotor shaft into a cavity delimited by an end cap of the rotor. The coolant can then flow from the cavity into the cooling channel. Alternatively, the coolant can be injected into the cooling channels through a nozzle that is firmly connected to the stator of the electrical machine. For this purpose, an end cap of the rotor can have one or more through openings through which the coolant is sprayed.

In addition, the invention relates to an electrical machine with a rotor of the type described and a stator which surrounds the rotor. The rotor can rotate relative to the stator. The stator can have a further laminated core (stator core), which is formed from stacked electrical laminations.

In addition, the stator can have windings of electrical conductors, for example in the form of coil windings or flat wire windings.

Furthermore, the invention relates to a vehicle with such an electric machine, which is provided for driving the vehicle. In particular, the machine can drive a wheel or an axle of the vehicle. The invention also relates to a method for producing a rotor of the type described. The method according to the invention comprises the following steps: arranging the laminated core on the rotor shaft, producing the rotor windings by winding enamelled copper wire around the projections of the laminated core, inserting pole separators each having a cooling channel between two adjacent projections of the laminated core, arranging a first end cap on a first axial side of the laminated core, arranging a second end cap on the second axial side of the laminated core, casting gaps between adjacent rotor windings and the pole separators with a casting compound, so that the pole separators are each cast into the casting compound be embedded.

For potting, the rotor is preferably positioned such that its axis of rotation is vertical and the potting compound is introduced through a filling opening in an end cap of the rotor, the end cap preferably also having a ventilation opening. The vent hole allows air to escape so that the gaps in the rotor can be fully potted.

The invention is explained below using exemplary embodiments with reference to the figures. The figures are schematic representations and show:

1 shows a sectional side view of a rotor according to the invention with a pole separator according to a first embodiment,

2 shows a section along the line II-II of FIG. 1,

3 shows an enlarged view in the area of a pole separator according to a second exemplary embodiment, 4 shows an enlarged view in the area of a pole separator according to a third embodiment, and

5 shows a vehicle according to the invention with an electric machine.

The rotor 1 shown in Figure 1 in a sectional side view and in Figure 2 in an axial view cut along the line II-II of Figure 1 according to a first embodiment of the invention is intended for an electrical machine that is used as an electric motor for driving a vehicle becomes.

The rotor 1 comprises a cylindrical laminated core 2 formed from stacked electrical laminations, which encloses a rotor shaft 3 in a positive and/or non-positive manner. The electrical sheets can be stamped parts of identical design. The laminated core 2 has a plurality of laminated core projections 4 (“teeth”) protruding radially outwards, as can be seen best in FIG. End sections of the laminated core projections 4 are widened in the circumferential direction.

A first end plate 5 is located on a first axial side of the laminated core 2. A second end plate 6 is located on the opposite, second axial side of the laminated core 2. The end plates 5, 6 have an electrically insulating coating or are made of an electrically non-conductive material such as a plastic manufactured. The end plates 5, 6 each have radial end plate projections 7, 8 (also "plate extensions") around which a plurality of rotor windings 9 are wound. The rotor windings 9 consist of lacquered copper wire.

In FIG. 2 it can be seen that a pole separator 10 is arranged between each two adjacent laminated core projections 4 . The rotor 1 has six rotor poles and six pole separators 10 . Such a pole separator 10 is designed as a plastic profile and is inserted axially between two adjacent rotor windings 9 which are wound around two adjacent laminated core projections 4 . The pole separator 10 closes a free space formed between the two rotor windings 9 and the two laminated core projections 4 . For this purpose, the cross section of the pole separator 10 is adapted to the shape of the free space.

The one-piece pole separator 10 comprises a wider, approximately trapezoidal, radially outer section 11 and an approximately rectangular, radially inner section 12. Three cooling channels 13 for a coolant run in the pole separator 10, which are lined up in a row in the radial direction.

The joints between the rotor windings 9 and the pole separator 10 can be cast with a casting compound. This causes the rotor windings 9 to maintain their position even at high speeds and improves the heat transfer from the rotor windings 9 or the laminated core 2 to the pole separator 10.

Referring again to FIG. 1, it can be seen that the cooling channels 13 in the pole separators 10 extend over their entire axial length. On both axial sides of the rotor 1 there is an end cap 14, 15 through which the rotor shaft 3 passes.

The arrows in FIG. 1 indicate the flow direction of the coolant as an example. The coolant can be a liquid, a gas or an oil, among others. All cooling channels 13 run straight and in the axial direction. Since the cooling passages 13 pass along the rotor windings 9, heat is transferred from the rotor windings 9 to the coolant flowing in the cooling passages 13 and dissipated. The rotor windings 9 are thereby cooled along their entire axial length. In the exemplary embodiment shown in FIG. 1, there is an inlet for coolant (not shown) on the left-hand side. The entrance can be designed differently. For example, the rotor shaft 3 can have one or more bores, through which the coolant is introduced from a central cooling channel arranged in the rotor shaft 3 into the cavity delimited by the end cap 14 . From there, the coolant can get into the cooling channels 13 .

Alternatively, the end cap 14 can have one or more passage openings through which the coolant is injected from a nozzle arranged in the housing of the electric machine through the end cap 14 into the cooling channels 13 .

On the opposite side, on the right in FIG. 1, within the end cap 15 is an outlet for the coolant, which corresponds to the inlet and is not shown. The outlet can be designed analogously either as a through opening in the end cap 15 or as a bore in the rotor shaft 3 .

In the method for manufacturing the rotor 1 , the laminated core 2 formed from stacked electrical laminations is arranged on the rotor shaft 3 with the laminated core projections 4 projecting radially outwards. Furthermore, the rotor windings 9 are produced by winding lacquered enamelled copper wire around the laminated core projections 4 of the laminated core 2 . The pole separators 10 are then each pushed in axially between two adjacent projections of the laminated core 2 . Thereafter, the two end caps 14, 15 are attached to both axial sides of the laminated core 2 by being pressed onto the end plates 5, 6.

The joints between the rotor windings 9 and the pole separators 10 are cast with a casting compound, as a result of which the rotor windings 9 and the pole separators 10 are embedded in the casting compound. For casting, the rotor 1 is expediently brought into a vertical position with respect to its axial direction. The casting compound is filled in through a filling opening (not shown) formed in one of the end caps. This end cap preferably also has a vent hole.

Figure 3 shows an enlarged view of a pole separator 16 according to a second embodiment of the invention. The pole separator 16 closes a gap between two adjacent laminated core projections 4 with its radially outer section. Its radially inner section is located between two adjacent rotor windings 9 and has several cooling channels 17 arranged along a radial axis (dash-dotted line), each of which has a circular cross section. The radially outer section of the pole separator 16 has two cooling channels 18 arranged in the circumferential direction on both sides of the radial axis, the cross sections of which correspond to the cooling channels 17 in the inner section.

FIG. 4 is a view similar to FIG. 3 and shows a pole separator 19 according to a third embodiment of the invention, which has only a single cooling channel 20. FIG. The cooling channel 20 has a Y-shaped cross section, which extends from a radially inner section of the pole separator 19 to a radially outer section of the pole separator 19 . In the radially inner section of the pole separator 19, the cross section has a straight first section running along a radial axis (dash-dotted line). In the radially outer section of the pole separator 19, the cross-section has two straight sections, each branching off from the first section, running obliquely to the radial axis along the rotor windings 9 and oriented symmetrically to one another with respect to the radial axis.

FIG. 5 shows a vehicle 21 with an electric machine 22 which is used to drive the vehicle 21 . The electrical machine 22 has a housing 23 in which the rotor 1 and a stator 24 which surrounds the rotor 1 are accommodated. reference list

1 rotor

2 laminated core

3 rotor shaft

4 laminated core protrusion

5 end plate

6 end plate

7 End Plate Boss

8 End Plate Boss

9 rotor winding

10 pole separators

11 outer section

12 inner section

13 cooling channel

14 end cap

15 end cap

16 pole separators

17 cooling channel

18 cooling channel

19 pole separators

20 cooling channel

21 vehicle

22 electric machine

23 housing

24 stator

Claims

patent claims 1 . Rotor (1) for an electrical machine (22), comprising: - a rotor shaft (3), - a laminated core (2) which is arranged on the rotor shaft (3) and is formed from stacked electrical laminations and has radially outwardly projecting laminated core projections (4), - Rotor windings (9) each wound around a core projection (4), and - A pole separator (10, 16, 19) arranged between two adjacent laminated core projections (4) and in which a cooling channel (13, 17, 18, 20) for a coolant runs. 2. Rotor (1) according to claim 1, wherein the cooling channel (13, 17, 18, 20) extends from one axial side of the laminated core (2) to the opposite axial side of the laminated core (2). 3. Rotor (1) according to claim 1 or 2, wherein the pole separator (10, 16, 19) has an inner portion (12) which is arranged between two adjacent rotor windings (9) and an outer portion (11) which is radial is arranged outside of the two rotor windings (9). 4. Rotor (1) according to claim 3, wherein the inner section (12) is embedded in a casting compound with which the two rotor windings (9) are cast. 5. Rotor (1) according to claim 3 or 4, wherein the cooling channel (13, 17, 18, 20) in the inner portion (12) and / or the outer portion (11) runs. 6. Rotor (1) according to any one of the preceding claims, wherein the cooling channel (13, 17, 18, 20) has a circular or Y-shaped cross-section. 7. Rotor (1) according to any one of the preceding claims, wherein the cooling channel (13, 17, 18, 20) in an end cap (14, 15) of the rotor (1) opens. 8. Rotor (1) according to one of the preceding claims, wherein the pole separator (10, 16, 19) has a plurality of cooling channels (13, 17, 18, 20) corresponding to the cooling channel (13, 17, 18, 20). 9. Rotor (1) according to one of the preceding claims, with a plurality of pole separators (10, 16, 19) corresponding to pole separators (10, 16, 19) which are each arranged between two adjacent laminated core projections (4) of the laminated core (2). 10. Electrical machine (22), with a rotor (1) according to any one of claims 1 to 9 and a rotor (1) surrounding the stator (24). 11 . Vehicle (21) with an electric machine (22) according to claim 10, which is provided for driving the vehicle (21). 12. A method for manufacturing a rotor (1) according to any one of claims 1 to 9, with the following steps: - arranging the laminated core (2) on the rotor shaft (3), - winding the rotor windings (9) around the laminated core protrusions (4) of the laminated core (2), - Insertion of the pole separator (10, 16, 19) between two adjacent laminated core projections (4) of the laminated core (2) and - Potting of the rotor windings (9) with a potting compound so that the pole separator (10, 16, 19) is embedded in the potting compound. 13. The method according to claim 12, wherein the rotor (1) is positioned for potting so that its axis of rotation is vertical and the potting compound is introduced through a filling opening in an end cap (14, 15). 15, the end cap (14, 15) preferably also having a vent opening.