ELECTRICAL MACHINE

Abstract

Electrical machine, e.g., a generator, having a stator comprising a winding overhang, a rotor arranged rotatable in the stator, and a heat exchanger fluidically connected to the winding overhang via a coolant shaft, which is arranged radially outside the winding overhang, runs at least partially approximately along a circumferential direction, and is delimited in a radial direction by an outer surface, so that the winding overhang can be cooled by a continuous flow of a fluid over the heat exchanger and the winding overhang. To obtain uniform cooling of the winding overhang, multiple guiding elements are arranged in a distributed manner along a circumferential direction in the coolant shaft to redirect a flow of a fluid oriented in a circumferential direction in the coolant shaft at least partially into a radial flow towards the winding overhang and to distribute the flow to multiple regions of the winding overhang.

Claims

1. An electrical machine, in particular a generator, having a stator comprising a winding overhang, a rotor arranged rotatably about a rotor axis in the stator, and a heat exchanger, wherein the heat exchanger is fluidically connected to the winding overhang via a coolant shaft, which is arranged radially outside the winding overhang, runs at least partially approximately along a circumferential direction, and is delimited in a radial direction by an outer surface, so that the winding overhang can be cooled by a continuous flow of a fluid over the heat exchanger and the winding overhang, wherein multiple guiding elements arranged in a distributed manner along a circumferential direction are provided in the coolant shaft in order to redirect a flow of a fluid oriented in a circumferential direction in the coolant shaft at least partially into a radial flow towards the winding overhang and to distribute the flow to multiple regions of the winding overhang.

2. The electrical machine according to claim 1, wherein the guiding elements are roughly radially oriented.

3. The electrical machine according to claim 1, wherein the outer surface is at least partially embodied roughly as a surface of revolution with the rotor axis in particular as an outer cylinder surface or outer cone surface.

4. The electrical machine according to claim 1, wherein, the guiding elements are arranged with an approximately equal spacing from the rotor axis.

5. The electrical machine according to claim 1, wherein 10 to 100, in particular 30 to 60, guiding elements are arranged in a distributed manner over a circumference.

6. The electrical machine according to claim 1, wherein the guiding elements are arranged with a spacing from the outer surface.

7. The electrical machine according to claim 6, wherein the guiding elements have different spacings from the outer surface, wherein the guiding elements have a smaller spacing from the outer surface at an increasing distance from the heat exchanger in the direction of flow.

8. The electrical machine according to claim 1, wherein a clear flow cross section between the outer surface and a guiding element continuously decreases, at least in some regions, from one guiding element to the next guiding element at an increasing distance from the heat exchanger in the direction of flow.

9. The electrical machine according to claim 1, wherein the guiding elements are embodied to be plate-shaped.

10. The electrical machine according to claim 1, wherein at least some guiding elements comprise a rounded edge, preferably on a discharge side, at an end that delimits a clear flow cross section between the outer surface and the guide elements.

11. The electrical machine according to claim 1, wherein the guiding elements are formed by elements connected in a fixed manner to the winding overhang, in particular by connection towers.

12. The electrical machine according to claim 1, wherein a fan, in particular an axial fan, is provided with which a flow of a fluid, in particular of air, can be produced in the machine from the heat exchanger through the coolant shaft to the winding overhang and hack to the heat exchanger.

13. The electrical machine according to claim 12, wherein the stator comprises two winding overhangs and each winding overhang is connected to the fan and the heat exchanger via a separate flow path.

14. The electrical machine according to claim 1, wherein separate flow paths are provided for an upper region of the winding overhang and a lower region of the winding overhang.

Description

[0039] FIG. 1 shows a machine according to the invention in a sectional illustration;

[0040] FIG. 2 shows a detail of a mac line according to the invention;

[0041] FIG. 3 shows a further detail of a machine according to the invention.

[0042] FIG. 1 shows an electrical machine according to the invention in a sectional illustration. As can be seen, the rotating electrical machine embodied as a motor generator is embodied in this case as a horizontal machine, which can be used in a hydroelectric power plant for example, and thus comprises a horizontal rotor axis 3. A machine according to the invention can, however, also be embodied as a vertical machine. The machine illustrated is embodied as an externally ventilated machine, wherein a fan 5 is arranged below a stator. Using the fan 5, a continuous fluid flow in the machine can be obtained, by which air or a different cooling fluid is transported, being divided into multiple partial volume flows, along the four schematically illustrated flow paths 4 from the fan 5 through air shafts to winding overhangs of the stator, where it is separately transported to upper and lower regions of the winding overhangs, at which heat is released by the winding overhang 1 to the cooling fluid.

[0043] Via an air gap 10 between the rotor 13 and stator, the cooling fluid subsequently reaches ventilation slots arranged in the stator, via which ventilation slots the cooling fluid flows radially outwardly through a laminated stator core 14 and thereby absorbs heat from the stator, whereupon the cooling fluid flows back to the fan 5 via the heat exchanger 6, embodied as an air-to-water heat exchanger 6 in this case, at which the cooling fluid emits heat. A return flow path of all four partial volume flows thus leads in this case through the air gap 10 and the laminated stator core 14.

[0044] As can be seen in FIG. 1, the entire machine is externally ventilated in this case by a fan 5 arranged below the stator, wherein the fan 5 can, of course, also be formed by multiple fan devices, for example by eight axial or radial fans.

[0045] As illustrated, an entire amount of air on which the fan 5 acts is preferably guided over the winding overhangs, so that a serial cooling is achieved, whereby a serially cooled horizontal machine is obtained.

[0046] In a fan outlet region, the volume flow for a winding overhang 1 on a connection side of the machine as well as a volume flow for a winding overhang 1 on a non-connection side of the machine are each divided into two parallel branches, wherein one branch supplies an upper region of the winding overhangs with cooling fluid and one branch supplies a lower region of the winding overhangs. This is expedient in this case, especially because an inflow side, from which the cooling fluid is transported to the winding overhang 1, is arranged here below the stator, so that flow paths 4 to the lower region of the winding overhang 1 are correspondingly shorter than flow paths 4 of the cooling fluid to the upper region of the winding overhang 1. By choosing appropriate cross sections of the flow paths 4 to the upper region and to the lower region, a very uniform flow into, and therefore cooling of, these regions, which are spaced apart from the fan 5 by different distances, can thus still be ensured. It shall be understood that, especially if the fan 5 were not positioned below, but rather at the side of the stator, a division into a left-hand region and a right-hand region of the winding overhang 1 could also be beneficial.

[0047] Furthermore, a division takes place to the two winding overhangs of the stator, that is, to a winding overhang 1 on a connection side of the stator and a winding overhang 1 on a non-connection side of the stator. The volume flow of the cooling fluid circulating in the machine is thus divided into four partial volume flows, as can be seen in FIG. 1 on the basis of the separate flow paths 4 to the winding overhangs.

[0048] FIG. 2 shows a portion of the connection side of the machine illustrated in FIG. 1. As can be seen, a portion of a housing 2 of the machine comprises a coolant shaft 17 through Which the cooling fluid is guided to the winding overhang by the fan 5, which is schematically illustrated in a lower region.

[0049] Additionally, in relation to the upper region of the winding overhang 1, a division of the volume flow takes place into a partial volume flow for a right-hand region of the winding overhang 1 and a partial volume flow for a left-hand region of the winding overhang 1. FIG. 2 shows a ventilation of one of these two portions, for example the left-hand portion. The machine region of the second portion is accordingly constructed symmetrically on a vertical center plane to the portion illustrated in FIG. 2, so that a flow in the upper region of the winding overhang 1 in said portion runs in an opposing manner to the illustrated portion.

[0050] The illustrated portion of the housing 2 comprises an approximately rotationally symmetrical inner region in which the winding overhang 1, which is not illustrated, is arranged. Because the fan 5 is, as can be seen, positioned below the winding overhang 1, a flow path 4 from the fan 5 to an upper region of the winding overhang 1 is longer than a flow path 4 to a lower region of the winding overhang 1. In order to nevertheless attain a most uniform possible cooling of individual regions of the winding overhang 1, separate flow paths 4 from the fan 5 to the lower region of the winding overhang 1 and to the upper region of the winding overhang 1 are provided on the one hand. The corresponding division is in this case achieved by a separating device 7, which can be embodied as a plate in a coolant shaft 17, for example.

[0051] On the other hand, guiding elements 11 are positioned in the coolant shaft 17, which guiding elements 11 are oriented approximately radially in order to redirect a flow in the coolant shaft 17 to one portion each, in order to radially apply a cooling an or a different fluid to the winding overhang 1, On the connection side illustrated, said guiding elements 11 are formed by connection towers in Which individual bars of the winding overhang 1 of the stator are electrically connected on the connection side.

[0052] On the non-connection side, which is located opposite from the connection side, the guiding elements 11 can be formed by guide plates arranged in the coolant shaft 17.

[0053] FIG. 3 shows in detail an upper region of the coolant shall 17 illustrated in FIG. 2 which has an outer surface that is roughly rotationally symmetrical to a rotor axis 3 of the generator, so that the coolant shall 17 is embodied here to be approximately arc-shaped.

[0054] In order to achieve a uniform cooling of the winding overhang 1, the guiding elements 11 extend, as depicted, radially farther outwardly at an increasing distance from the heat exchanger 6 in a direction of flow, so that at each guiding element 11, a further region of a flow running in a circumferential direction 9 in the coolant shaft 17 is shaved off, or is redirected inwardly into a radial flow that is applied to the respective region of the winding overhang 1 in order to cool said winding overhang 1.

[0055] FIG. 3, like FIG. 2, shows only a portion of the coolant shaft 17 for ventilating a left-hand portion of the winding overhang 1, wherein the corresponding right-hand portion is embodied symmetrically. Accordingly, in the right-hand portion not illustrated, the guiding elements 11 also extend radially farther outwardly at an increasing distance from the heat exchanger 6 in the direction of flow, and the flow in said right-hand portion runs in an opposing manner to the indicated direction of flow.

[0056] A clear flow cross section 12 between the guiding elements 11 and the outer surface thus continuously decreases from one guiding element 11 to the next guiding element 11 along the direction of flow, wherein said direction of flow can be oriented both in a circumferential direction 9 and opposite to the circumferential direction 9. As a result, it is easily ensured that each of the guiding elements 11 redirects a portion of the flow into a radial flow inwardly towards the winding overhang 1 and a shadowing of guiding elements 11 located downstream is compensated.

[0057] The individual guiding elements 11 are thus, as depicted, each spaced apart from the outer surface, whereby it is ensured that only a portion of the volume flow flowing in a circumferential direction 9 is redirected inwardly in a radial direction 8, so that a volume flow also remains for the portions of the winding overhang 1 that are located downstream in the direction of flow in order to visualize this, velocity vectors 16 of the cooling fluid or cooling medium are illustrated in the coolant shaft 17.

[0058] Furthermore, it can be seen that the guiding elements 11 are embodied to be rounded at a radially outer end, namely on a discharge side. A rounding 1 of an edge on a side of the guiding element 11 arranged downstream can thereby have a radius of 1 mm to 20 mm, for example. As a result, turbulences which would have negative effects on the redirection are avoided in this region.

[0059] A machine embodied according to the invention exhibits a particularly uniform cooling of the winding overhang region, so that hot spots that could result w damage are effectively avoided.