Rotor assembly of a separately excited electric machine of a vehicle

Abstract

The invention relates to a rotor assembly of a separately excited electric machine (13), having a hollow rotor shaft (1), a laminated core (3) and a plurality of coils (5) which are arranged next to one another in the circumferential direction, wherein respectively adjacent coils (5) are held by means of a winding holder (6) and are spaced apart 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 accumulating chamber (7) extending axially in a cavity between adjacent coils (5) is provided for receiving coolant, wherein the accumulating chamber (7) is fluidically connected to the interior (2) of the hollow rotor shaft (1) for supplying coolant, and wherein a reduced outflow of the coolant from the accumulating chamber (7) can be realised by at least one limiting element (8) in the region of at least one end of the accumulating chamber (7). The invention further relates to a separately excited electric machine (13) having a rotor assembly. The invention also relates to a vehicle (14) comprising at least one separately excited electric machine (13).

Description

[0001] Rotor arrangement of a foreign-temperature electrical machine of a vehicle

[0002] 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.

[0003] 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.

[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 12 or 13, 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 a plurality of coils arranged side by side in the circumferential direction, wherein adjacent coils are held 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 structurally simple and cost-effective direct and sufficient cooling of the rotor, in particular of the coils, at least one accumulation chamber extending axially in a cavity between adjacent coils is provided for accommodating coolant, wherein the accumulation chamber is fluidly connected to the interior of the hollow rotor shaft for supplying coolant, and wherein, in the region of at least one end of the accumulation chamber, a reduced outflow of the coolant from the accumulation chamber can be realized by at least one limiting element.

[0007] In the proposed rotor arrangement, a hollow space or cavity between two adjacent coils is used as a storage chamber to accommodate 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 provided limiting elements 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. The available hollow space in the storage chamber is thus optimally utilized as an additional cooling path to dissipate the heat generated in the coils directly from the rotor.

[0008] It is particularly preferred if the limiting element is assigned to at least one end of each accumulation chamber and is shaped, at least in the region of the assigned end of the accumulation chamber, such that an overflow is provided that limits the accumulation chamber. In this way, a reduced outflow of the coolant from the accumulation chamber through the limiting element is achieved in a structurally simple manner, so that 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. Thus, regardless of the volume flow of the coolant or cooling medium, a predetermined coolant level in the accumulation chamber is ensured in the proposed rotor arrangement.For example, in the proposed rotor arrangement, an outer shape of the plate-shaped limiting element facing one end of the storage chamber can be designed in a longitudinal section with a ramp or similar shape to reduce the radial distance between the limiting element and the laminated core. The selected shape of the limiting element enables a simple and cost-effective design of the overflow.

[0009] Preferably, a corresponding limiting element or the like can be assigned to each end of the storage chamber, so that an overflow is realized on both sides in the storage chamber.

[0010] The proposed rotor arrangement features a particularly simple design for the accumulation chamber, which is circumferentially bounded by adjacent coils, radially outwardly by the associated winding holder and the limiting elements, and radially inwardly by the laminated core. Thus, the accumulation chamber is designed with a simple design, allowing it to serve 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.

[0011] 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.

[0012] It is particularly preferred in the proposed rotor arrangement that the radial bore is axially located approximately centrally of the axially extending storage chamber. In this way, the coolant can be conveyed centrally from the hollow rotor shaft into the associated storage chamber, so that, due to the centrifugal forces that occur, the coolant can flow or be distributed axially in both directions of the storage chamber. Particularly with a central supply of the coolant to each storage chamber, it has proven particularly advantageous with regard to cooling performance to assign a limiting element to each end of the storage chamber to reduce outflow.

[0013] To optimize the cooling performance of the proposed rotor arrangement, the coils distributed around the circumference of the laminated core can be held by winding holders, with each winding holder being assigned a storage chamber between two adjacent coils. The winding heads at a first end of the coils are jointly secured via a first support ring, and the winding heads at a second end of the coils are jointly secured via a second support ring. Each storage chamber is fluidly connected to the interior of the hollow rotor shaft for coolant supply.

[0014] When arranging multiple circumferentially distributed storage chambers, it is particularly advantageous if the limiting elements assigned to a first end of the circumferentially distributed storage chambers are preferably molded onto the first support ring, and if the limiting elements assigned to a second end of the circumferentially distributed storage chambers are molded onto the second support ring. In this way, the function of the support ring is expanded to include the limiting function at each storage chamber, and separate limiting elements as components are eliminated, since these are now designed as a single piece with the respective support ring.

[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] 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.

[0017] 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.

[0018] The present invention is further explained below with reference to the drawings.

[0019] They show:

[0020] Figure 1 is a longitudinal sectional 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 limiting elements between adjacent coils;

[0021] Figure 2 is a cross-sectional view of the rotor arrangement with several storage chambers distributed around the circumference between adjacent coils supplied with coolant from the hollow rotor shaft;

[0022] Figure 3 is a detailed view of support rings provided with limiting elements for securing associated winding heads of the coils (not shown in detail); Figure 4 is a longitudinal section of the rotor arrangement with several radial bores distributed around the circumference on the hollow rotor shaft for supplying coolant to the storage chambers and with arrows indicating the coolant flow;

[0023] Figure 5 is a longitudinal section of the rotor arrangement with limiting elements provided in the storage chambers as overflows for accumulating the coolant indicated by dots in the storage chambers; and

[0024] Figure 6 is a detailed view of a winding holder of the rotor assembly.

[0025] Figures 1 to 6 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.

[0026] 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.

[0027] In order to realize direct cooling of the coils 5 of the rotor arrangement, an axially extending storage chamber 7 for receiving coolant is formed in the hollow space or cavity between adjacent coils 5, wherein the storage chamber 7 is fluidly connected to an interior space 2 of the hollow rotor shaft 1, through which coolant flows, for supplying coolant, wherein in the region of at least one end of the storage chamber 7, a reduced outflow of the coolant from the storage chamber 7 can be realized by at least one limiting element 8. The limiting element 8 faces the end of the storage chamber 7, wherein the region facing the end of the storage chamber 7 is shaped such that an overflow limiting the storage chamber 7 is provided.The overflow is formed by the facing outer forum of the approximately plate-shaped limiting element 8 being designed in a longitudinal section with an approximately ramp-shaped or similar configuration to reduce the radial distance between the limiting element 8 and the laminated core 3. As can be seen in particular from Figure 1, a limiting element 8 is assigned to each end of the storage chamber 7. Each limiting element 8 essentially forms a barrier at the associated end of the storage chamber 7, for example, in the form of a fin or the like.

[0028] As can be seen from Figure 2, for example, a coil 5 is assigned to each pole 4 distributed over the circumference of the star-shaped laminated core 3, 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. Thus, each storage chamber 7 is delimited in the circumferential direction by associated adjacent coils 5 and radially outwardly by the associated winding holder 6 and by the delimiting elements 8, as well as radially inwardly by the laminated core 3.

[0029] Figure 3 shows a first support ring 9 and a second support ring 10 without the laminated core 3 arranged between them with the coils 5 on the hollow rotor shaft 1. The winding heads at a first end of the coils 5 are fastened or held together via the first support ring 9 and the winding heads at a second end of the coils 5 are fastened or held together via the second support ring 10. The limiting elements 8 assigned to a first end of the accumulation chambers 7 arranged distributed over the circumference are integrally formed on the first support ring 9, while the limiting elements 8 assigned to a second end of the accumulation chambers 7 arranged distributed over the circumference are integrally formed on the second support ring 10.The plate-shaped limiting elements 8, designed as a barrier in the form of fins, are arranged distributed over the inner circumference of the support rings 9, 10 and are oriented radially inwards, wherein the outer shape of each limiting element 8, which is ramp-shaped in longitudinal section, is oriented axially in the direction of the associated end of the storage chamber 7 on the respective support rings 9, 10.

[0030] The flow connection between the interior 2 of the hollow rotor shaft 1 and the storage chambers 7 is realized by a plurality of 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 indicated, for example, in Figures 4 and 5.

[0031] In Figure 4, the flow path of the coolant is indicated by arrows, while in Figure 5 the accumulation of the coolant in the accumulation chambers 7 is indicated by points on the limiting elements 8 designed as overflows.

[0032] Figure 6 shows an individual part view of the winding holder 6. The winding holder 6 has a central base body for radially defining the associated storage chamber 7, with wing-like regions 15, 16 formed on both sides of the central base body of the winding holder 6. Each wing-like region 15, 16 is assigned to a coil 5 for fastening it to the laminated core 3. The base body of the winding holder 6 serves to space the two adjacent coils 5 apart.

[0033] Reference symbol

[0034] Hollow rotor shaft

[0035] Interior of the rotor hollow shaft

[0036] Rotor lamination package

[0037] Poles of the star-shaped laminated core

[0038] Wash

[0039] Winding holder

[0040] storage chamber

[0041] Limiting element first support ring second support ring

[0042] Pole head ring

[0043] Radial bore separately excited electrical machine or electric motor

[0044] Vehicle wing-like area molded onto the base body of the winding holder wing-like area molded onto the base body of the winding holder

Claims

Patent claims 1. A rotor arrangement of a separately excited electrical machine (13) with 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, and wherein the hollow rotor shaft (1) has an interior space (2) through which coolant flows, characterized in that 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, in the region of at least one end of the accumulation chamber (7), a reduced outflow of the coolant from the accumulation chamber (7) can be realized by at least one limiting element (8).

2. Rotor arrangement according to claim 1, characterized in that the limiting element (8) is assigned to at least one end of the storage chamber (7) and is shaped at least in the region of the assigned end of the storage chamber (7) such that an overflow limiting the storage chamber (7) is provided.

3. Rotor arrangement according to claim 1 or 2, characterized in that an outer forum of the plate-shaped limiting element (8) facing one end of the storage chamber (7) is designed in a substantially ramp-shaped manner in longitudinal section in order to reduce the radial distance between the limiting element (8) and the laminated core (3).

4. Rotor arrangement according to one of the preceding claims, characterized in that a limiting element (8) is assigned to each end of the storage chamber (7).

5. Rotor arrangement according to one of the preceding claims, characterized in that the accumulation chamber (7) is defined in the circumferential direction by associated adjacent coils (5) and radially outwardly by the associated winding holder (6) and by at least one limiting element (8) and radially inwardly by the laminated core (3).

6. Rotor arrangement according to one of the preceding claims, characterized in that the flow connection between the hollow rotor shaft (1) and the storage chamber (7) is provided by at least one radial bore (12) extending through the hollow rotor shaft (1) and the laminated core (3).

7. Rotor arrangement according to claim 6, characterized in that the radial bore (12) is assigned approximately centrally to the axially extending storage chamber (7).

8. Rotor arrangement according to one of the preceding claims, characterized in that each end of the storage chamber (7) is assigned a limiting element (8) for reduced outflow.

9. Rotor arrangement according to one of the preceding claims, characterized in that the coils (5) arranged distributed over the circumference of the laminated core (3) are held by winding holders (6), each winding holder (6) being assigned a storage chamber (7) between two adjacent coils (5), the winding heads at a first end of the coils (5) being fastened together by a first support ring (9) and the winding heads at a second end of the coils (5) being fastened together by a second support ring (10), and each storage chamber (7) being fluidly connected to the interior (2) of the hollow rotor shaft (1) for the purpose of supplying coolant.

10. Rotor arrangement according to claim 9, characterized in that the limiting elements (8) assigned to a first end of the accumulation chambers (7) distributed over the circumference are formed onto the first support ring (9) and that the limiting elements (8) assigned to a second end of the accumulation chambers (7) distributed over the circumference are formed onto the second support ring (10).

11. Rotor arrangement according to one of the preceding claims, characterized in that the laminated core (3) surrounding the hollow rotor shaft (1) is designed in cross-section approximately star-shaped with several radially outwardly projecting 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).

12. Separately excited electrical machine (13) with a rotor arrangement according to one of the preceding claims.

13. Vehicle (14) with at least one separately excited electrical machine (13) according to claim 12.

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