Rotor arrangement of a separately excited electrical machine of a vehicle

Abstract

A rotor arrangement of a separately excited electrical machine (13) is proposed, comprising a hollow rotor shaft (1) with a laminated core (3) and with a plurality of coils (5) arranged side by side in the circumferential direction, wherein adjacent coils (5) are held by a winding holder (6) and spaced from one another in the circumferential direction, wherein the hollow rotor shaft (1) has an interior space (2) through which coolant flows, wherein at least one accumulation chamber (7) extending axially in a cavity between adjacent coils (5) is provided for receiving coolant, wherein the accumulation chamber (7) is fluidly connected to the interior space (2) of the hollow rotor shaft (1) for supplying coolant, and wherein a predetermined shape (15) of the winding holder (6), provided at least in sections, in the region of at least one end of the accumulation chamber (7) enables a reduced outflow of the coolant from the accumulation chamber (7).Furthermore, a separately excited electric machine (13) with a rotor arrangement is proposed. Furthermore, a vehicle (14) with at least one separately excited electric machine (13) is proposed.

Description

[0001] The present invention relates to a rotor arrangement of a separately excited electrical machine according to the type described in the preamble of claim 1. Furthermore, the invention relates to an electrical machine with a rotor arrangement and a vehicle with a separately excited electrical machine.

[0002] Separately excited electrical machines are known from automotive engineering, for example, as electric motors, in which a magnetic rotor field is generated by the current flowing through several coils on a laminated core of the rotor shaft. Due to the increased power of separately excited electrical machines, significantly higher cooling capacity is required to minimize thermal losses. It has been shown that rotor cooling by a hollow rotor shaft through which coolant flows is insufficient to adequately dissipate the heat generated in the rotor, especially in the rotor coils.

[0003] Devices for rotor cooling are known from the prior art, for example from EP 2 985 885 A1, DE 10 2022 109 033 A1 or US7,146,707 B2.

[0004] Accordingly, the object of the present invention is to propose a rotor arrangement of a separately excited electrical machine and a separately excited electrical machine with the rotor arrangement as well as a vehicle with the separately excited electrical machine, which enables direct cooling of the coils in a structurally simple and cost-effective manner.

[0005] This object is achieved according to the invention by the features of patent claim 1 or 10 or 11, wherein advantageous and claimed developments result from the subclaims and the description as well as the drawings.

[0006] Accordingly, a rotor arrangement of a separately excited electrical machine is proposed, comprising a hollow rotor shaft with a laminated core and with a plurality of coils arranged next to one another in the circumferential direction, wherein adjacent coils are radially secured by a winding holder and spaced from one another in the circumferential direction, and wherein the hollow rotor shaft has an interior space through which coolant flows.In order to enable a structurally simple and cost-effective direct and sufficient cooling of the rotor, in particular of the coils, at least one axially extending accumulation chamber for receiving coolant is provided in a cavity between adjacent coils, wherein the accumulation chamber is fluidly connected to the interior of the hollow rotor shaft for supplying coolant and wherein a reduced outflow of the coolant from the accumulation chamber can be realized by a predetermined shape of the winding holder provided at least in sections in the region of at least one end of the accumulation chamber.

[0007] In the proposed rotor arrangement, a hollow space or cavity between two adjacent coils is used as a storage chamber for the cooling medium or coolant. Since the storage chamber is fluidly connected to the interior of the hollow rotor shaft through which coolant flows, the rotation of the hollow rotor shaft causes the coolant to be conveyed quasi-automatically or forcibly from the interior into the storage chamber by centrifugal force. Due to the predetermined shape of the winding holder and the associated reduced outflow of coolant from the storage chamber, the coolant accumulates in the storage chamber so that the outer surfaces of two adjacent coils are sufficiently wetted with coolant from the associated storage chamber for direct cooling. Thus, the available hollow space in the storage chamber is optimally used as an additional cooling path to dissipate the heat generated in the coils directly from the rotor.

[0008] Furthermore, the shape of the winding holder in the region of at least one end of the accumulation chamber is designed in the radial direction such that an overflow or the like is provided that delimits the accumulation chamber. In this way, a reduced outflow of the coolant from the accumulation chamber is achieved in a structurally simple manner without additional components due to the shape of the winding holder. The coolant continuously entering due to the rotation of the hollow rotor shaft is dammed up to a predetermined overflow height due to the overflow formed. This ensures a predetermined coolant level in the accumulation chamber with the proposed rotor arrangement, regardless of the volume flow of the coolant or cooling medium.

[0009] For example, in the proposed rotor arrangement, the shape of the winding holder in longitudinal section toward at least one end of the storage chamber can be approximately ramp-shaped or similar to reduce the radial distance between the winding holder and the laminated core. This type of winding holder shape is an example of a simple and cost-effective design for the overflow.

[0010] The shape or design of the winding holder for radially defining the accumulation chamber, at least in sections, can take any desired form. It is particularly advantageous if the shape of the winding holder, in longitudinal section, forms a trough shape or the like, defined by the overflows at the ends of the accumulation chamber, in order to achieve a turbulent inflow of the coolant. According to the invention, the shape of the winding holder, in longitudinal section, forms two adjacent trough shapes or the like, each defined by an overflow and, for example, a centrally arranged radial elevation or the like, in order to achieve a laminar inflow of the coolant through the symmetrical arrangement of the two trough shapes.

[0011] The proposed rotor arrangement features a particularly simple design for the accumulation chamber, which is circumferentially bounded by adjacent coils, radially outwardly by the shape of the associated winding holder, and radially inwardly by the laminated core. Thus, no additional components are required to implement the accumulation chamber as an additional cooling path in the proposed rotor arrangement. Sealing elements can also be used to prevent any leaks that may occur at the coils.

[0012] To ensure a simple and cost-effective supply of coolant to the storage chamber from the hollow rotor shaft, the fluid connection between the hollow rotor shaft and the storage chamber can be provided by at least one radial bore or similar device running through the hollow rotor shaft and the laminated core. Other connection options are also conceivable, allowing a coolant supply without the need for additional components.

[0013] It is particularly preferred in the proposed rotor arrangement that the radial bore is axially located approximately centrally of the axially extending storage chamber. This allows the coolant to be conveyed centrally from the hollow rotor shaft into the associated storage chamber, so that, due to the resulting centrifugal forces, the coolant can flow or be distributed axially in both directions of the storage chamber.

[0014] In particular, when the coolant is fed centrally into the storage chamber, it has proven particularly advantageous in terms of cooling performance that the storage chamber has a reduced outflow at each end.

[0015] With the proposed rotor arrangement, various rotor designs are possible. It is particularly advantageous if the laminated core surrounding the hollow rotor shaft has a cross-section that is approximately star-shaped or similar, with several radially outward-facing poles, whereby each pole of the star-shaped laminated core is assigned a coil with a winding encircling the pole. Accordingly, the windings of the coils each revolve around the assigned pole, so that the coils and their windings are distributed side by side in the circumferential direction around the circumference of the laminated core. In this type of design as an assembled rotor with so-called air-core coils, the individual components are attached axially and radially to the hollow rotor shaft. This construction principle enables an open coil design, in which the cooling medium can advantageously and easily utilize the existing cavity between adjacently arranged coils to wet the coil surfaces.

[0016] In order to optimize the cooling performance of the proposed rotor arrangement, it can be provided that the coils arranged distributed over the circumference of the laminated core are held by winding holders, wherein each winding holder is assigned a storage chamber which is fluidly connected to the hollow rotor shaft for the coolant supply.

[0017] The object underlying the invention is also achieved by a separately excited electrical machine with the rotor arrangement described above, whereby the advantages already described and further advantages are obtained.

[0018] The object underlying the invention is also achieved by a vehicle with at least one separately excited electric machine with the rotor arrangement described above, whereby the advantages already described and further advantages are obtained.

[0019] The present invention is further explained below with reference to the drawings.

[0020] They show: Fig. 1 a longitudinal section view of a first embodiment of a rotor arrangement according to the invention of a separately excited electrical machine with a hollow rotor shaft with a laminated core and with several coils arranged next to one another in the circumferential direction and with two storage chambers for cooling, each delimited by winding holders between adjacent coils; Fig. 2 a longitudinal section view of a second embodiment of the rotor arrangement with a modified shape of the winding holder; Fig. 3 a cross-sectional view of the rotor arrangement with several storage chambers distributed over the circumference between adjacent coils supplied with coolant from the hollow rotor shaft; Fig. 4 a longitudinal section view of the first embodiment of the rotor arrangement with several radial bores distributed over the circumference on the hollow rotor shaft for supplying coolant to the storage chambers and with arrows indicating the coolant flow; Fig. 5 is a longitudinal sectional view of the first embodiment of the rotor arrangement with overflows provided in the storage chambers for accumulating the coolant indicated by dots; Fig. 6 a detail view of a winding holder of the first embodiment of the rotor arrangement according to Fig. 1; and Fig. 7 a detail view of a winding holder of the second embodiment of the rotor arrangement according to Fig. 2.

[0021] In the Fig. 1 to 7 show various views of a rotor arrangement according to the invention of a schematically indicated separately excited electrical machine 13 in a schematically indicated vehicle 14 by way of example.

[0022] The rotor arrangement has a hollow rotor shaft 1 with an interior space 2 through which coolant flows to cool the rotor. The hollow rotor shaft 1 is surrounded by a laminated core 3, which has an approximately star-shaped cross-section with several radially outward-pointing poles 4, wherein each pole 4 of the star-shaped laminated core 3 is assigned a coil 5 with a winding encircling the pole 4. The coils 5, which are arranged side by side in the circumferential direction and encircle adjacent poles 4, are held together by a winding holder 6 and are spaced apart from one another in the circumferential direction by the winding holder 6, such that a hollow space or cavity is formed between the adjacent coils 5.

[0023] In order to realize direct cooling of the coils 5 of the rotor arrangement, an axially extending accumulation chamber 7 for receiving coolant is formed in the hollow space or cavity between adjacent coils 5, wherein the accumulation chamber 7 is fluidly connected to an interior space 2 of the hollow rotor shaft 1 through which coolant flows for the purpose of supplying coolant, wherein a reduced outflow of the coolant from the accumulation chamber 7 is realized by a predetermined shape 15 of the associated winding holder 6 provided at least in sections in the region of at least one end of the accumulation chamber 7.

[0024] The shape 15 of the winding holder 7 is designed in the radial direction in the region of the two ends of the storage chamber 7 such that an overflow 8 is provided at each end of the storage chamber 7, limiting the outflow of the coolant from the storage chamber 7. The overflow 8 is formed by the shape 15 of the winding holder 6 being designed in a substantially ramp-shaped manner in the longitudinal section toward the end of the storage chamber 7 to reduce the radial distance between the winding holder 6 and the laminated core 3.

[0025] In the first variant according to Fig. 1, the shape 15 of the winding holder 6 forms a quasi trough shape 9 for at least partially radially limiting the storage chamber 7 in longitudinal section, which is limited by the two overflows 8 at the ends of the storage chamber 7.

[0026] In the second variant according to Fig. 2, the modified shape 15 of the winding holder 6 for at least partially radially delimiting the storage chamber 7 in longitudinal section forms two trough shapes 9 arranged next to one another, which are delimited on the one hand by an associated overflow 8 and on the other hand by a common radial elevation 10 in the middle between the two trough shapes 9.

[0027] Regardless of the design variants, the accumulation chamber 7 is limited in the circumferential direction by the adjacent coils 5 and radially outwardly by the shape 15 of the associated winding holder 6 and radially inwardly by the laminated core 3.

[0028] For example, Fig. 3, each pole 4 distributed over the circumference of the star-shaped laminated core 3 is assigned a coil 5, wherein the coils 5 distributed over the circumference are held by the winding holders 6, wherein the winding holders 6 are supported radially on an associated pole head ring 11. Each winding holder 6 is assigned two adjacent coils 5, between which a storage chamber 7 is formed, wherein each storage chamber 7 is fluidly connected to the interior 2 of the hollow rotor shaft 1 for the coolant supply.

[0029] The flow connection between the interior 2 of the hollow rotor shaft 1 and the storage chambers 7 is realized by several radial bores 12 distributed over the circumference of the hollow rotor shaft 1, wherein the radial bores 12 run through the hollow rotor shaft 1 and the laminated core 3 and thus open into the respective storage chamber 7 approximately centrally, as is the case, for example, in the Fig. 4 and Fig. 5 is indicated.

[0030] In Fig. 4 the flow path of the coolant is indicated by arrows, while in Fig. 5 the accumulation of the coolant in the storage chambers 7 is indicated by dots on the overflows 8.

[0031] In Fig. Figure 6 shows a detailed view of the winding holder 6 according to the first embodiment. In the first embodiment, a trough shape 9 is formed in longitudinal section through the shape 15 of the winding holder 6, which radially delimits the storage chamber 7. This trough shape 9 is delimited by the two overflows 8 at the ends. Wing-like regions 16, 17 are formed on both sides of a central base body of the winding holder 6 forming the shape 15. Each wing-like region 16, 17 is assigned to a coil 5 in order to attach it to the laminated core 3. The base body of the winding holder 6 serves to space the two adjacent coils 5 apart.

[0032] In Fig.Figure 7 shows a detailed view of the winding holder 6 according to the second embodiment. In contrast to the first embodiment, in the second embodiment, two trough shapes 9 are formed side by side in the longitudinal section through the shape 15 of the winding holder 6 radially delimiting the storage chamber 7. These trough shapes are delimited on the one hand by a radial elevation 10 arranged centrally between the two trough shapes 9 and on the other hand by an associated overflow 8. Reference symbol 1 hollow rotor shaft 2 Interior of the hollow rotor shaft 3 Rotor lamination package 4 poles of the star-shaped laminated core 5 coils 6 winding holders 7 storage chamber 8 Overflow 9 Tub shape 10 radial elevation 11 Pole head ring 12 Radial bore 13 separately excited electrical machine or electric motor 14 vehicles 15 radial shape of the winding holder delimiting the storage chamber 16 wing-like area formed on the base body of the winding holder 17 wing-like area formed on the base body of the winding holder

Claims

[1] Rotor arrangement of a separately excited electrical machine (13) comprising a hollow rotor shaft (1) with a laminated core (3) and with a plurality of coils (5) arranged next to one another in the circumferential direction, wherein adjacent coils (5) are held by a winding holder (6) and spaced from one another in the circumferential direction, and wherein the hollow rotor shaft (1) has an interior space (2) through which coolant flows, at least one axially extending accumulation chamber (7) in a cavity between adjacent coils (5) for receiving coolant, wherein the accumulation chamber (7) is fluidly connected to the interior (2) of the hollow rotor shaft (1) for supplying coolant, and wherein a reduced outflow of the coolant from the accumulation chamber (7) can be achieved by a predetermined shape (15) of the winding holder (6) provided at least in sections in the region of at least one end of the accumulation chamber (7), wherein the shape (15) of the winding holder (6) in the region of at least one end of the storage chamber (7) is designed in the radial direction such that an overflow (8) delimiting the storage chamber (7) is provided, and wherein the shape (15) of the winding holder (6) for at least partially radially delimiting the storage chamber (7) forms, in longitudinal section, two trough shapes (9) arranged next to one another, which are each delimited by an overflow (8) and a centrally arranged radial elevation (10). [2] Rotor arrangement according to claim 1, characterized by that the shape (15) of the winding holder (6) in the longitudinal section towards at least one end of the storage chamber (7) is approximately ramp-shaped in order to reduce the radial distance between the winding holder (6) and the laminated core (3). [3] Rotor arrangement according to claim 1 or 2, characterized bythat the shape (15) of the winding holder (6) for at least partially radially delimiting the storage chamber (7) forms in longitudinal section a trough shape (9) delimited by the overflows (8) at the ends of the storage chamber (7). [4] Rotor arrangement according to one of the preceding claims, characterized by that the accumulation chamber (7) is limited in the circumferential direction by associated adjacent coils (5) and radially outwardly by the shape (15) of the associated winding holder (6) and radially inwardly by the laminated core (3). [5] Rotor arrangement according to one of the preceding claims, characterized by that the flow connection between the hollow rotor shaft (1) and the storage chamber (7) is provided by at least one radial bore (12) running through the hollow rotor shaft (1) and the laminated core (3). [6] Rotor arrangement according to claim 5, characterized by that the radial bore (12) is assigned approximately centrally to the axially extending storage chamber (7). [7] Rotor arrangement according to one of the preceding claims, characterized by that the storage chamber (7) has a reduced outflow at each end. [8] Rotor arrangement according to one of the preceding claims, characterized by that the laminated core (3) surrounding the hollow rotor shaft (1) is designed in cross-section approximately star-shaped with several radially outward-pointing poles (4), wherein each pole (4) of the star-shaped laminated core (3) is assigned a coil (5) with a winding rotating around the pole (4). [9] Rotor arrangement according to one of the preceding claims, characterized by that the coils (5) arranged distributed over the circumference of the laminated core (3) are held by means of winding holders (6), wherein each winding holder (6) is assigned a storage chamber (7) between two adjacent coils (5), and wherein each storage chamber (7) is fluidly connected to the interior (2) of the hollow rotor shaft (1) for the purpose of supplying coolant. [10] Separately excited electrical machine (13) with a rotor arrangement according to one of the preceding claims. [11] Vehicle (14) with at least one separately excited electrical machine (13) according to claim 10.

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