Rotor with fluid guidance system for cooling fluid

Abstract

To provide improved cooling of a rotor for an electric machine, a rotor (100) for an electric machine is proposed comprising at least one rotor winding (10) made of an electrical conductor and comprising at least one protective device (11) for protecting an axial end-side region (12) of at least one rotor winding segment (10a) forming a rotor pole of the at least one rotor winding (10), wherein the protective device (11) has at least one fluid guidance system (13) for guiding a cooling fluid (13a), wherein the fluid guidance system (13) is formed in a section (15) of the protective device (11) arranged between the rotor winding (10) and a rotor core, in particular a rotor lamination stack (14), of the rotor (100).

Description

[0001] The invention relates to a rotor for an electrical machine, a protective device designed for use in such a rotor and an electrical machine comprising such a rotor.

[0002] Various cooling concepts for cooling electrical machines are known from the state of the art. In particular, cooling fluid-based systems are known in which a cooling fluid is directed along the components of the electrical machine to dissipate heat generated during operation of the electrical machine.

[0003] For example, DE 10 2018 220 810 A1 discloses a fluid-cooled rotor for an electrical machine and a separately excited synchronous machine (FSM) with a directly or near-loss cooled rotor winding with a hollow shaft for the passage of a cooling fluid.

[0004] Furthermore, US 2019 / 0273406 A1 discloses a stator or a rotor for an electrical machine having an end cap with one or more cap channels for guiding a cooling fluid.

[0005] During the manufacture of electrically excited synchronous machine (EESM) rotors, end caps are fitted to protect the rotor windings during winding, as winding machines (e.g., needle winders or flyer winders) wind the wires. These end caps are usually made of injection-molded material and have low thermal conductivity. Therefore, heat dissipation from the rotor lamination to the end cap is very low.

[0006] The invention is based on the object of providing improved cooling of a rotor for an electrical machine.

[0007] This object is achieved by a rotor for an electrical machine comprising at least one rotor winding made of an electrical conductor and comprising at least one protective device for protecting an axial end region of at least one rotor winding segment forming a rotor pole of the at least one rotor winding, wherein the protective device has at least one fluid guide system for guiding a cooling fluid, wherein the fluid guide system is formed in a section of the protective device arranged between the rotor winding and a rotor core, in particular a rotor laminated core, of the rotor.

[0008] The fluid guidance system advantageously enables heat to be dissipated from the rotor in the area of ​​the rotor winding by guiding a cooling fluid through the fluid guidance system in the area between the rotor winding and the rotor core. This advantageously makes it possible to manufacture the protective device cost-effectively using an injection molding process while simultaneously enabling heat dissipation in the area of ​​the rotor core. Furthermore, the rotor core cooling function can be advantageously integrated into the existing protective device, requiring no additional components.

[0009] The protective device is, in particular, an end cap of the rotor or an end cap of the electric machine. The end cap is preferably designed such that it covers at least one, preferably all, rotor winding segments of an axial end side of the rotor, at least in part, in order to protect the rotor winding during the winding process. For example, the protective device can cover the axial end region of the rotor winding segment laterally, i.e., in the region of the circumference of the rotor. Furthermore, the rotor winding can be partially wound around a section of the protective device, wherein this section is the section between the rotor winding of each rotor winding segment and the rotor core.

[0010] Preferably, the protective device is attached to the rotor, in particular in the region of the rotor shaft or on the rotor shaft.

[0011] The electric machine is, in particular, an electrically excited synchronous machine, which preferably comprises a rotor core stack. The cooling fluid is, in particular, a cooling oil.

[0012] The rotor winding segments are, in particular, those sections of the rotor winding that form one pole of the rotor. Each rotor winding segment therefore comprises two axial end regions.

[0013] The protective device is preferably designed to protect at least one, preferably all, rotor winding segments of one or both axial end regions.

[0014] The fluid guide system preferably has a fluid inlet opening facing a shaft of the rotor and at least one fluid outlet opening associated with an outer circumference of the rotor. A cooling fluid can be supplied to the fluid guide system through the fluid inlet opening and the fluid outlet opening, in particular through a fluid supply in the region of the rotor shaft, i.e., radially inward. For example, the rotor shaft can be designed as a hollow shaft, wherein the cooling fluid is supplied within the hollow shaft and is fed to the fluid inlet opening through an outlet arranged axially or radially in the rotor shaft. The cooling fluid is guided from the fluid inlet opening through the fluid guide system to the fluid outlet opening, wherein the cooling fluid absorbs and dissipates heat from the region between the rotor winding and the rotor core.

[0015] The fluid outlet opening is preferably arranged in the region of the outer circumference of the rotor, i.e., radially outward, in particular opposite the fluid inlet opening. The cooling fluid emerging from the fluid outlet opening can then preferably be further used to cool the stator by being propelled into the stator, in particular the stator windings or a winding head of the stator windings, as a result of the rotation of the rotor.

[0016] The fluid guide system preferably has at least one, particularly preferably two or three, fluid channel or channels extending between the fluid inlet opening and the fluid outlet opening. In the case of multiple fluid channels, these can preferably be arranged such that they cover the largest possible area of ​​the section between the rotor winding and the rotor core in order to increase the effectiveness of heat dissipation. For example, the fluid channels can be arranged spaced from one another, in particular uniformly, in a radial plane. The multiple fluid channels are preferably connected at their beginning and end to a collecting line, which is each connected to the fluid inlet opening and the fluid outlet opening. In the simplest case, the fluid guide system is formed by a single fluid channel and a corresponding fluid inlet opening and fluid outlet opening.

[0017] The at least one fluid channel preferably has a linear or non-linear profile. A non-linear profile can be advantageous for dissipating heat from as many areas as possible between the rotor winding and the rotor core. For example, the fluid channel can have a serpentine, jagged, or angular profile. Alternatively, the fluid channel can have a straight profile. The at least one fluid channel can also have the previously described profile only in certain areas. A transition region that connects the individual fluid channels to the fluid inlet or outlet opening can, in particular, have a different profile.

[0018] The fluid guidance system preferably comprises a cavity in which the cooling fluid is guided, wherein a plurality of pins extending into the cavity are arranged within the cavity to form a pin-fin cooling system. The pin-fin system enables particularly effective heat dissipation, since the pins provide a large surface area for heat transfer. The cavity is preferably connected to the fluid inlet and the fluid outlet opening.

[0019] The protective device preferably comprises a plurality of fluid guidance systems, wherein the rotor comprises a plurality of poles each formed by a rotor winding section, wherein each pole of the rotor is assigned a fluid guidance system. Accordingly, the protective device in particular has a plurality of sections, each of which contains a fluid guidance system, wherein the sections are each arranged between the rotor windings and the rotor core of the respective rotor winding section or pole.

[0020] The protective devices of an axially end-side region of the rotor winding preferably form a one-piece protective device part, which is in particular disc-shaped. In particular, the protective device part or the protective device is produced by means of an injection molding process and consists of or comprises plastic. In this context, "disc-shaped" means in particular that the protective devices are arranged substantially in one plane. The individual protective devices can preferably extend radially outward from a central fastening region for fastening to the rotor or the rotor shaft. In particular, the sections between the rotor winding and a rotor core and the at least one fluid channel of the fluid guide system extend radially outward.

[0021] The rotor preferably comprises two protective devices, with each of the two axial end regions of each rotor winding being assigned a protective device. The two protective devices are, in particular, identical or different in design. For example, the protective devices can differ in the shape and number of fluid guidance systems.

[0022] The object of the invention is further achieved by a protective device designed for use in a rotor according to one of the preceding claims.

[0023] Furthermore, the object of the invention is achieved by an electrical machine, in particular an electrically excited synchronous machine, comprising a rotor with the aforementioned features. Such an electrical machine can be used in particular in an electric vehicle.

[0024] The electric machine preferably comprises a cooling fluid circulation system which supplies the cooling fluid to the fluid inlet opening and cools the cooling fluid thrown into the stator through the fluid outlet opening and then supplies it back to the fluid inlet opening.

[0025] The cooling fluid circulation system can preferably be designed passively, wherein the cooling fluid is conveyed via a transmission conveying device of a vehicle, or the coolant circulation system can alternatively be designed actively, wherein a separate conveying device, for example a pump, is provided.

[0026] The cooling fluid is preferably supplied in both the active and passive case either to the rotor shaft, which can be designed as a hollow shaft with an integrated cooling channel, or to the fluid inlet opening via cooling channels in the rotor core, in particular in the rotor laminated core.

[0027] After the cooling fluid has passed through the fluid guide system and been thrown into the stator winding heads, the cooling fluid flows preferentially into a cooling fluid sump or cooling fluid reservoir of the electric machine. The cooling fluid then flows preferentially into the electric machine's gearbox.

[0028] Appropriate heat exchangers are preferably provided for cooling the cooling fluid. These heat exchangers can be, for example, plate heat exchangers or heat exchanger surfaces, which are preferably integrated into a housing of the electrical machine.

[0029] The invention is explained in more detail below using exemplary embodiments. They show, in purely schematic representations: Fig. 1 a perspective partial view of a rotor with protective device, Fig. 2 a plan view of an axial end region of a rotor winding segment of the rotor, Fig. 3 a plan view of an axial end region of a rotor lamination with a protective device and a fluid channel, Fig. 4 a plan view of the protective device, Fig. 5 a perspective view of the protective device, Fig. 6 an axial plan view of the protective device with a stator winding head, Fig. 7 a side view of a rotor winding segment and a stator winding head, Fig. 8 a protective device according to a first embodiment, Fig. 9 a protective device according to a second embodiment, Fig. 10 a protective device according to a third embodiment, and Fig. 11 a cooling fluid circuit in an electrical machine.

[0030] Fig. 1 shows a rotor 100 with a rotor winding 10 made of electrical conductors and a protective device 11. The rotor winding 10 forms several rotor winding segments 10a, each corresponding to a pole of the rotor 100. The rotor 100 or the rotor winding segments 10a have two axial end regions 12, wherein Fig. 1 shows a perspective top view of one of the two axial end regions 12. To protect the rotor windings of the individual rotor winding segments 10a, the rotor 100 comprises a protective device 11, which extends with a section 15 between the rotor winding 10 and a rotor core designed as a rotor core 14. The protective device 11 has a cap 15a on the radial end of the section 15, which protects the rotor winding 10 in the region of the individual rotor winding segments 10a during the winding process. The protective device 11 is fastened to a shaft 16, which extends in the axial direction A. The protective device 11 is designed such that the cooling fluid 13a can be discharged via a corresponding fluid outlet opening 17 (not shown here) in the region of the outer circumference 19 of the rotor 100.

[0031] Fig. Figure 2 shows a plan view of one of the rotor winding segments 10a. It shows that the protective device 11, with its section 15, extends between the rotor core 14 and the rotor winding 10. Fig. Figure 3 shows a further top view of one of the rotor winding segments 10a, additionally showing a fluid guidance system 13 in the form of a fluid channel 19a for guiding a cooling fluid 13a, which is incorporated in the protective device 11. The fluid channel 13a borders the rotor core 14 and thus enables effective heat dissipation from the area between the rotor core 14 and the rotor winding 10.

[0032] As in Fig. As shown in Figure 4, the fluid channel 19a is formed by a recess in the protective device 11. This makes it particularly easy to manufacture the fluid channel 19a in the protective device 11, especially if the protective device 11 is manufactured using an injection molding process.

[0033] Fig. Figure 5 shows a perspective view of a protective device 11. The protective device 11 is designed as a one-piece protective device part and in this embodiment comprises 8 radially projecting sections 15, the number of which corresponds to the number of poles of the rotor 100. The protective device 11 is arranged essentially in a disc shape and can be fastened to the shaft 16 (not shown here). Caps 15a are arranged on the sections 15 at the radial ends. At the rear of the sections 15 and thus in Fig. 5 not visible are the fluid channels which form the fluid guidance system 13.

[0034] Fig. 6 shows an axial plan view of the protective device 11 on the side which has the fluid guide system 13. In the embodiment according to Fig. 6, the fluid guide system 13 is formed by a single, linear or rectilinear fluid channel 19a with a corresponding fluid inlet opening 17, which is arranged in the region of the outer circumference 19 of the rotor 100 when installed on the rotor 100, and a fluid outlet opening 18, which is arranged in a region of the protective device 11 facing the shaft 16 of the rotor 100. Shown in Fig. 6 also shows a stator winding head 22 of a stator of an electrical machine. Cooling fluid 13a, which emerges from the fluid outlet opening 18 of the protective device 11, is propelled into the stator winding head 22 in order to cool it as well using the cooling fluid 13a.

[0035] Fig. Figure 7 shows a side view from an axial perspective of a rotor winding segment 10a. Fig. 8 to 10 show further embodiments of the fluid guidance system 13, wherein the region of the rotor winding 10 is shown semi-transparent for illustrative purposes. In each of the embodiments, the fluid guidance system 13 comprises a fluid inlet opening 17 and a fluid outlet opening 18.

[0036] In the embodiment according to Fig. 8, a single, non-linear fluid channel 19a is provided. The fluid channel 19a has a zigzag-like shape to cover the largest possible area of ​​the adjacent rotor core 14 or the rotor winding 10, thus increasing the cooling performance.

[0037] Alternatively, as in Fig. As shown in Figure 9, several, in this case three, fluid channels 19a, 19b, 19c may be provided, each having a linear, rectilinear course. The number of fluid channels 19a, 19b, 19c may vary, and only two or four or more fluid channels 19a, 19b, 19c may be provided.

[0038] Fig. Figure 10 shows an embodiment of the fluid guidance system 13, wherein the fluid guidance system 13 is configured as a pin-fin system. For this purpose, the fluid guidance system 13 or section 15 of the protective device 11 comprises a cavity 20 into which a plurality of pins 21 protrude in the axial direction. The cooling fluid 13a can flow around the pins 21 within the cavity 20, thus ensuring heat transfer.

[0039] Fig. 11 shows various variants of a cooling fluid circuit of the electric machine using a rotor 100 with the protective device 11.

[0040] The cooling fluid circuit can either be designed passively, wherein the cooling fluid 13a is conveyed via a transmission conveying device (not shown) of a vehicle, or the coolant circuit can alternatively be designed actively, wherein a separate oil pump 25 is provided, which is coupled to a heat exchanger 26.

[0041] In both the active and passive case, the cooling fluid 13a can be supplied either to the rotor shaft, which can be designed as a hollow shaft with an integrated fluid line 27, or to the fluid inlet opening 17 of the protective device 11 via fluid channels 28 in the rotor laminated core.

[0042] After the cooling fluid 13a has passed through the fluid guide system and been thrown into the stator winding heads 22 of the stator, the cooling fluid 13a enters a cooling fluid sump 29 or cooling fluid reservoir 23 of the electric machine. The cooling fluid 13a then enters the gearbox of the electric machine.

[0043] Appropriate devices are provided for recooling the cooling fluid 13a. These can be, for example, plate heat exchangers 24, heat exchanger 26 coupled to oil pump 25, or heat exchanger surfaces (not shown here), which are preferably integrated into a housing of the electric machine. List of reference symbols 100 rotors 10 rotor winding 10a Rotor winding segments 11 Protective device 12 axial end area 13 Fluid guidance system 13a Cooling fluid 14 Rotor lamination package Section 15 15a cap 16 Wave 17 Fluid inlet opening 18 Fluid outlet opening 19 Outer circumference of the rotor 19a, b, c Fluid channels 20 cavity 21 pins 22 Stator winding head 23 Cooling fluid tank 24 plate heat exchangers 25 Oil pump 26 heat exchangers 27 Fluid line in hollow shaft 28 Fluid line in rotor core 29 Cooling fluid sump A axial extension R radial extension QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 220 810 A1

[0003] US 2019 / 0273406 A1

[0004]

Claims

[1] Rotor (100) for an electrical machine comprising at least one rotor winding (10) made of an electrical conductor and comprising at least one protective device (11) for protecting an axial end region (12) of at least one rotor winding segment (10a) forming a rotor pole of the at least one rotor winding (10), wherein the protective device (11) has at least one fluid guide system (13) for guiding a cooling fluid (13a), wherein the fluid guide system (13) is formed in a section (15) of the protective device (11) arranged between the rotor winding (10) and a rotor core, in particular a rotor laminated core (14), of the rotor (100). [2] Rotor (100) according to claim 1, wherein the fluid guide system (13) has a fluid inlet opening (17) facing a shaft (16) of the rotor (100) and at least one fluid outlet opening (18) associated with an outer circumference (19) of the rotor (100). [3] Rotor (100) according to claim 2, wherein the fluid guide system (13) has at least one, preferably two or three, fluid channel (19a, 19b, 19c) extending between the fluid inlet opening (17) and the fluid outlet opening (18). [4] Rotor (100) according to claim 3, wherein the at least one fluid channel (19a, 19b, 19c) has a linear or a non-linear course. [5] Rotor (100) according to one of claims 1 to 4, wherein the fluid guide system (13) comprises a cavity (20) in which the cooling fluid (13a) can be guided, wherein a plurality of pins (21) projecting into the cavity (20) are arranged within the cavity (20) to form a pin-fin cooling system. [6] Rotor (100) according to one of the preceding claims, wherein the protective device (11) comprises a plurality of fluid guide systems (13), and wherein the rotor (100) comprises a plurality of poles each formed by a rotor winding segment (10a), wherein each pole of the rotor (100) is assigned a fluid guide system (13). [7] Rotor (100) according to claim 6, wherein the protective devices (11) of an axial end region (12) of the rotor winding (10) form a one-piece protective device part, which is in particular disc-shaped. [8] Rotor (100) according to one of the preceding claims, comprising two protective devices (11), wherein each of the two axial end regions (12) of each rotor winding (10) is assigned a protective device (11). [9] Protective device (11) designed for use in a rotor (100) according to one of the preceding claims. [10] An electrical machine comprising a rotor (100) according to any one of claims 1 to 8.

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