Generator for wind turbine, outer rotor for generator for wind turbine, and wind turbine

Abstract

The utility model relates to a generator for a wind turbine, an outer rotor of the generator for the wind turbine and the wind turbine. The utility model relates to a generator comprising an inner stator and an outer rotor rotatably mounted about an axis of rotation extending in a longitudinal direction of the outer rotor wherein an air gap is provided between the inner stator and the outer rotor wherein the outer rotor comprises a hollow cylindrical rotor housing and a plurality of magnet means, the magnet means are arranged in several rows extending in a longitudinal direction at an inner surface of the rotor housing, where the inner surface comprises at least one groove-like longitudinal recess extending in the longitudinal direction and covered by the magnet means in one of the rows, where the inner surface comprises at least one groove-like circumferential recess extending in the longitudinal direction and covered by the magnet means in one of the rows, where the inner surface comprises at least one groove-like circumferential recess extending in the longitudinal direction and covered by the magnet means in the other of the rows. The groove-like circumferential recess extends in a circumferential direction and connects the longitudinal recess with the air gap.

Description

Technical Field

[0001] The utility model relates to a generator for a wind turbine, which comprises an inner stator and an outer rotor. The outer rotor is rotatably mounted around a rotation axis extending along the longitudinal direction of the outer rotor. An air gap is provided between the inner stator and the outer rotor. The outer rotor comprises a hollow cylindrical rotor housing and a plurality of magnet devices, which are arranged in several rows extending along the longitudinal direction at the inner surface of the rotor housing. The inner surface comprises at least one groove-shaped longitudinal recess, which extends along the longitudinal direction and is covered by the magnet devices in one of the rows.

[0002] In addition, the utility model relates to an outer rotor for a generator of a wind turbine, which comprises a hollow cylindrical rotor housing and a plurality of magnet devices, which are arranged in several rows extending along the longitudinal direction at the inner surface of the rotor housing. The inner surface comprises at least one groove-shaped longitudinal recess, which extends along the longitudinal direction and is covered by the magnet devices in one of the rows. Further, the utility model relates to a wind turbine. Background Art

[0003] A wind turbine generally comprises a hub having several blades, wherein the hub is mounted such that it can rotate around a rotation axis. The wind-driven rotation of the hub is transferred to the rotor of the generator. The generator is usually arranged in a nacelle, which is arranged on top of a tower of the wind turbine. Modern wind turbines can have a total height of several tens or hundreds of meters. The output power of the generator can be in the range of several megawatts, especially between 1 and 40 megawatts.

[0004] Electrical losses occur in the stator and the rotor, and this results in the need to cool these components. For this purpose, air, especially ambient air from the vicinity of the wind turbine or air circulating within a cooling circuit, can be guided to the generator, wherein the air is in thermal contact with the stator and / or the rotor and removes heat from these components.

[0005] A specific aspect regarding the cooling of generators for wind turbines is the dissipation of heat caused by electrical losses in the permanent magnets, the magnet substrates and the rotor housing carrying the permanent magnets. In addition, wind turbines located in regions with hot climatic conditions experience the following problem: due to the high ambient temperature, the magnet temperature may rise above the safety limit, which has a negative impact on the magnet properties.

[0006] EP 4109717 A1 discloses a generator for a direct drive wind turbine, in which a cylindrical rotor housing carries a plurality of magnet assemblies. These magnet assemblies are located at the inner housing surface and are arranged in a plurality of rows. The inner housing surface includes groove-shaped recesses which are covered by the magnet assemblies in one of the rows. Between pairs of magnet assemblies, a gap is provided which extends in the circumferential direction and communicates with the recesses. The gap leads to the air gap between the rotor and the stator and to the recesses such that an air flow from the air gap through the gap into the recesses is possible.

[0007] EP 2601728 B1 discloses an electric machine having a rotor, in which permanent magnets are arranged on the rotor body. The rotor body includes grooves or recesses extending along the longitudinal direction of the rotor, wherein the recesses cause a reduction in the contact area between the permanent magnets and the rotor body to increase the magnetic holding force of the permanent magnets. SUMMARY OF THE INVENTION

[0008] The object of the present utility model is to provide an improved concept of an air cooling system suitable for cooling permanent magnets of an outer rotor of a generator for a wind turbine.

[0009] To achieve this object, according to the present utility model, the generator as initially described is characterized in that the inner surface includes at least one groove-shaped circumferential recess which extends in the circumferential direction and connects the longitudinal recess with the air gap.

[0010] Regarding the definition of directions, the direction pointing vertically away from the axis of rotation can be defined as the radial direction. The direction pointing vertically away from the radial direction and towards the point of rotation of the rotor about the axis of rotation can be defined as the circumferential direction.

[0011] The present utility model is based on the idea that in particular groove-shaped longitudinal recesses which are usually used to increase the magnetic holding force of permanent magnets are additionally used to implement an air passage for cooling the corresponding magnet modules. To achieve a sufficient cooling effect, it is advantageous if air can leave or enter the longitudinal recesses at a position spaced apart from the front side of the longitudinal recesses in the circumferential recesses, because otherwise heat accumulation would occur at the corresponding positions. In particular, if air can only enter the longitudinal recesses at the openings located on the front end side of the longitudinal recesses, the resulting cooling effect is usually not sufficient to achieve sufficient cooling. According to the present utility model, the corresponding communication between the longitudinal recesses and the air gap is achieved by the circumferential recesses which constitute an air flow path from the longitudinal recesses to the air gap or vice versa.

[0012] In contrast to the system of EP 4109717 A1, the corresponding air flow path is realized by a cooling channel which is formed by a circumferential recess, in particular a grooved circumferential recess, of the rotor housing. Thus, according to the present invention, there is no need for a gap between the magnet devices, thereby respectively improving the flexibility of the structural design of the corresponding generator or rotor. In particular, relative to the gap between the magnet devices of EP4109717A1, the circumferential recess can be wider than the possible maximum width of the gap between the magnet devices. Therefore, the amount of cooling air guided through the recess can be increased, and thus, the cooling effect can be increased.

[0013] According to the present invention, the air flowing through or present in the air gap can branch laterally from the air gap into the circumferential recess and branch laterally from the circumferential recess into the longitudinal recess. Conversely, the air present under the magnet device in the longitudinal recess can flow into the air gap via the circumferential recess. The air transfer between the air gap and the recess can be driven by convection and / or by an air pump, in particular an air fan, which forms an air flow guided through the air gap. The air gap can have a width of about a few millimeters. The longitudinal direction of the circumferential recess can extend perpendicular to the longitudinal direction of the longitudinal recess. According to the present invention, a complex air path system including an air gap, a longitudinal recess and a circumferential recess is realized such that air flows along several sides of the magnet device to provide an enhanced cooling effect.

[0014] The longitudinal recess and / or the circumferential recess are groove-shaped. In other words, the corresponding recess can be a groove realized by a notch or deepening of the inner surface. The longitudinal recess can extend straight along a line. The longitudinal recess can extend over the entire longitudinal extension of the rotor. Regarding its longitudinal direction, the shape of the circumferential recess can be circular or arc-shaped. Regarding its cross-section, the shape of the circumferential recess can be rectangular, in particular square.

[0015] The longitudinal recess is covered by the magnet devices in one of the rows. Thus, several magnet devices are arranged along a straight line which extends in the longitudinal direction and is parallel to the longitudinal extension of the longitudinal recess. At least one lateral wall of the air channel formed by the longitudinal recess can be realized by the outer surface of the rotor housing, i.e., by the outer surface forming the corresponding groove. The other lateral wall arranged opposite to the lateral wall realized by the outer surface of the rotor is realized by the lower surface of the magnet device in contact with the inner surface of the rotor housing. Assuming that the air channel realized by the longitudinal recess has a rectangular cross-section, three side walls of this channel can be realized by the groove forming the longitudinal recess, and one side wall can be realized by the lower surface of the magnet device.

[0016] In possible embodiments of the present invention, several circumferential recesses may be provided along the longitudinal direction of the rotor. The circumferential recesses may be spaced apart evenly or unevenly along the longitudinal direction. Most preferably, at least one circumferential recess is provided below each of the magnet modules.

[0017] The generator according to the present invention may be a distributed winding generator or a concentrated winding generator. The stator of the generator includes a winding wound around the stator teeth. In the case of a distributed winding, the corresponding winding is wound around at least two stator teeth. In the case of a concentrated winding, the corresponding winding is wound around one stator tooth.

[0018] According to the present invention, the circumferential recess or one of the circumferential recesses may be a central recess disposed at the longitudinal center of the rotor. The corresponding circumferential recess may be exactly in the middle of the longitudinal extension of the rotor or slightly offset from this position. At the longitudinal middle of the rotor, the magnet modules are expected to have the highest temperature. Therefore, the corresponding circumferential recess and the enhanced cooling effect generated at this position are advantageous.

[0019] In a specific embodiment of the present invention, the circumferential recess or at least one of the circumferential recesses is a connecting recess that connects at least two adjacent longitudinal recesses to each other. In this embodiment, the corresponding circumferential recess communicates with more than one longitudinal recess. Therefore, the air flowing through the adjacent longitudinal recesses branches laterally into the same circumferential recess, that is, enters the connecting recess from opposite directions. Between the corresponding longitudinal recesses, especially in the middle, the connecting recess may lead radially outward to the air gap. In particular, the circumferential recess or at least one of the circumferential recesses connects more than two, especially all, longitudinal recesses to each other.

[0020] The circumferential recess or at least one of the circumferential recesses may be a non-connecting recess that only connects the longitudinal recess or one of the longitudinal recesses to the air gap. In this embodiment, the corresponding circumferential recess communicates only with one of the longitudinal recesses. The non-connecting recess leads to the corresponding longitudinal recess at one end and to the air gap at the other end. The opening of the non-connecting recess may be located between two adjacent longitudinal recesses, especially in the middle thereof.

[0021] According to the present invention, several sets of connecting recesses and / or non-connecting recesses may be provided, wherein the circumferential recesses in each set of the sets extend along a common circumferential line, wherein the circumferential line of the set is arranged along the longitudinal direction, and wherein the circumferential recesses in two adjacent sets are alternating. In this embodiment, a labyrinth air path system is achieved.

[0022] In a possible embodiment of the present utility model, at least one of the magnet devices includes a permanent magnet located on a substrate, wherein the substrate is attached to a rotor housing for arranging this magnet device on the inner surface. The substrate (which may be made of metal) constitutes the connection interface between the permanent magnet of the corresponding magnet device and the inner surface or the rotor housing. The substrate is positioned or arranged between the corresponding permanent magnet and the inner surface. The permanent magnet is attached to the substrate, in particular, by means of glue connection or the like.

[0023] The shape of the permanent magnet may be prismatic or cubic. The shape of the substrate may be rectangular, and the sides of the substrates of adjacent magnet devices in one row, including the shorter sides of the same length, in particular the sides of the corresponding rectangles, may be positioned next to each other, have a gap between each other, or be in contact with each other.

[0024] At least one of the magnet devices, in particular the substrate of this magnet device or a substrate, includes a T-shaped attachment section, wherein the rotor housing includes a T-shaped groove on the inner surface, and the attachment section is inserted into the groove to attach the magnet device to the rotor housing. In this embodiment, the magnet device, in particular the substrate, includes two laterally protruding tongues that extend from the main body of the substrate in the circumferential direction. The T-shaped attachment section may be realized by the substrate. The shape of the T-shaped groove corresponds to the shape of the attachment section, in particular such that a form fit between the attachment section and the groove is achieved to attach the magnet device to the inner surface. To attach the magnet device to the inner surface, the magnet device may be inserted into the groove along the longitudinal direction and through an opening on its front end face via the groove. The longitudinal recess may extend along the bottom surface of the groove.

[0025] The T-shaped shape of the attachment section and / or the groove may be interrupted in the region of the circumferential recess or at least one of the circumferential recesses. In this embodiment, the opening of the corresponding circumferential recess leading to the air gap is enlarged compared to the case where the T-shaped shape is not interrupted. The interruption of the T-shaped shape may be present at a position spaced apart from the longitudinal end of the corresponding magnet device or substrate, in particular in the longitudinal middle. This ensures that the corresponding magnet device is sufficiently and firmly held via the corresponding T-shaped shape at its longitudinal ends.

[0026] In a preferred embodiment, at least two of the rows are spaced apart from each other in the circumferential direction. The openings of the circumferential recesses leading to the air gap may be arranged in the space between the corresponding rows. In particular, the rows are evenly distributed in the circumferential direction.

[0027] Adjacent magnet devices in at least one of the rows can be in contact with each other. This contact in particular ensures the airtightness of the longitudinal recess arranged below this row, in particular without the need for a separate sealant. However, alternatively, a gap can be provided between the magnet devices to form an opening of the longitudinal recess towards the air gap.

[0028] According to a possible embodiment, several circumferential recesses with different cross-sectional areas are provided. The cross-sectional area can be rectangular and have a specific width and height, where the cross-sectional area is the product of these ranges multiplied. The circumferential recess or one of the circumferential recesses arranged at the longitudinal center of the rotor can include a larger cross-sectional area than the circumferential recesses arranged at the longitudinal outer part of the rotor. The specific selection of the cross-sectional area depends on the specific cooling requirements and can be adjusted as desired.

[0029] The present utility model also relates to an outer rotor as initially described, wherein the inner surface includes at least one groove-shaped circumferential recess extending along the circumferential direction, and in the state where the outer rotor is installed in the generator, the at least one circumferential recess connects the longitudinal recess to the air gap provided between the inner stator and the outer rotor of the generator. All aspects, features, and advantages described with respect to the generator according to the present utility model can be transferred to the outer rotor according to the present utility model, and vice versa.

[0030] In addition, the present utility model relates to a wind turbine including the generator described above. The wind turbine can be a direct-drive wind turbine. In this embodiment, the rotational frequency of the outer rotor of the generator is equal to the rotational frequency of the hub because the hub is directly connected to the generator, that is, there is no gearbox in between. All aspects, features, and advantages described with respect to the generator according to the present utility model and / or with respect to the outer rotor according to the present utility model can be transferred to the wind turbine according to the present utility model, and vice versa.

[0031] The wind turbine according to the present utility model may be characterized in that the air cooling system is a cooling circuit or an open system and includes at least one air pump, in particular an air fan, wherein the air pump is adapted to pump cooling air to the air gap and / or the longitudinal recess. The air pump can be a ventilator or a fan respectively. If the air cooling system is a cooling circuit, the cooling circuit can implement a thermodynamic cooling cycle. If the air cooling system is an open system, ambient air can be inhaled from the vicinity of the wind turbine, in particular respectively through the inlet opening of the wind turbine or the nacelle. After the air has passed through the rotor, it can be discharged again into the vicinity area, in particular respectively through the outlet opening of the wind turbine or the nacelle.

[0032] Regarding the air cooling system, the longitudinal channel or at least one of the longitudinal channels may open at at least one of the lateral ends of the rotor, particularly at both lateral ends. If the longitudinal channel or at least one of the longitudinal channels opens at both lateral ends, an air supply chamber may be provided on each of the two axial face ends of the rotor, wherein the air supply chamber communicates with the air gap and the corresponding longitudinal channel. The air pump may be adapted to pump cooling air into the air supply chamber such that the cooling air is then guided into the air gap and the longitudinal recesses such that it also enters the circumferential recesses. Thus, a part of the cooling air enters the air gap while another part of the cooling air enters the longitudinal recesses. Specifically, air enters the air gap and the longitudinal recesses from both axial sides such that the air flows in opposite directions. Regarding the longitudinal recesses, air may leave the longitudinal recesses through the circumferential recesses, particularly in the central region, and enter the air gap. Regarding the air gap, air may leave the air gap through at least one radial air channel of the stator, particularly in the central region. The radial air channel may be realized by a gap between the laminated metal sheets forming the stator. The radial air channel is connected to the air gap at one of its lateral ends and to an air discharge chamber at its other end. If a closed cooling system is provided, the air discharge chamber may be connected to the air supply chamber; or if an open cooling system is provided, the air discharge chamber may be connected to the vicinity of the wind turbine.

[0033] In an alternative embodiment, an air supply chamber may be provided axially on the face end of the rotor and an air discharge chamber may be provided axially on the face end of the rotor, the air discharge chamber being arranged opposite to the air supply chamber, wherein the air gap and the longitudinal recesses communicate with the air supply chamber and the air discharge chamber. In contrast to the embodiment described in the previous section, the air in the air gap and the longitudinal recesses flows in one direction, i.e., in the direction leading from the air supply chamber to the air discharge chamber. Air leaves and enters the air gap and the longitudinal recesses through the axial ends of the air gap and the longitudinal recesses. The longitudinal recess or at least one of the longitudinal recesses may be closed at its longitudinal end face such that air can enter the corresponding longitudinal recess only via the air gap and the circumferential recess. In this embodiment, the air supply chamber and / or the air discharge chamber communicate directly with the air gap without communicating with the channels. Description of the Drawings

[0034] Other objects and features of the present utility model will become apparent from the following detailed description considered in conjunction with the accompanying drawings. However, these drawings are only schematic diagrams designed for illustrative purposes and do not limit the present utility model. The drawings show:

[0035] Figure 1 Shows a view of a wind turbine according to an embodiment of the present invention, the wind turbine comprising a generator according to an embodiment of the present invention, wherein the generator comprises an outer rotor according to an embodiment of the present invention,

[0036] Figure 2 Shows a longitudinal sectional view through Figure 1 the generator of the wind turbine,

[0037] Figure 3 Shows the same view of the generator as Figure 2 wherein a first possible variant of the cooling system of the wind turbine is shown,

[0038] Figure 4 Shows the same view of the generator as Figure 2 wherein a second possible variant of the cooling system of the wind turbine is shown,

[0039] Figure 5 Shows a radial sectional view through Figure 1 the generator of the wind turbine, wherein the generator corresponds to a first embodiment of the present invention,

[0040] Figure 6 Shows a longitudinal sectional view through Figure 5 the outer rotor of the generator, wherein the cutting plane is indicated by VI–VI in Figure 5 ,

[0041] Figure 7 Shows a longitudinal sectional view through Figure 5 the generator, wherein the cutting plane is indicated by VII–VII in Figure 3 ,

[0042] Figure 8 Shows a radial sectional view through Figure 5 the generator, wherein the cutting plane is indicated by VIII–VIII in Figure 6 ,

[0043] Figure 9 – Figure 11 Shows the same view as Figure 6 wherein a possible variant of the first embodiment of the generator is shown,

[0044] Figure 12 Shows the same view as Figure 8 wherein the generator corresponds to a second embodiment of the present invention, and

[0045] Figure 13 – Figure 20 Shows the same view as Figure 6Same view, showing possible variants of a second embodiment of the generator. Detailed description

[0046] Figure 1 Figure 1 shows a wind turbine 1 according to an embodiment of the present invention. The wind turbine 1 comprises a tower 2, on which a nacelle 3 is arranged. In front of the nacelle 3, a hub 4 is provided, which is provided with a plurality of, in particular three, blades 5. The hub 4 is mounted such that it can rotate about a rotational axis 6. The wind-driven rotation of the hub 4 is transferred to a generator 7 according to an embodiment of the present invention, which is located in the nacelle 3. The rotation of the hub 4 is transferred to the generator 7 via a main shaft 8 extending along the rotational axis 6. Alternatively, the hub 4 and the generator 7 are directly connected, i.e., there is no main shaft 8 therebetween. Thus, the rotational frequency of the hub 4 can be equal to the rotational frequency of the generator 7. The rotational axis 6 defines the longitudinal direction 12 of the wind turbine 1 and the generator 7. The rotational axis 6 is arranged horizontally, but can also be inclined with respect to the horizontal direction. Although the total height of the wind turbine 1 is in the order of tens or hundreds of meters, the output power of the wind turbine 1 generated by the generator 7 can be in the range of several megawatts, in particular between 1 and 40 megawatts. The wind turbine 1 is a direct drive wind turbine. The generator 7 is a concentrated or distributed winding generator.

[0047] The generator 7 comprises an inner stator 10 and an outer rotor 11, which is a component according to an embodiment of the present invention. The inner stator 10 and the outer rotor 11 are arranged within a housing 9 of the generator 7. Although the inner stator 10 is non-rotatably mounted, the shaft (not shown in the figures) of the outer rotor 11 is connected to the main shaft 8 such that the rotation of the hub 4 is transferred to the outer rotor 11. Thus, the outer rotor 11 can rotate about the rotational axis 6. An air gap 22 with a width of several millimeters is provided between the inner stator 10 and the outer rotor 11.

[0048] Next, certain directions with respect to the wind turbine 1 or the generator 7 or the outer rotor 11 will be defined. The longitudinal direction 12 extends along or parallel to the direction of the rotational axis 6. The direction pointing vertically away from the rotational axis 6 is defined as the radial direction 13. The direction pointing vertically away from the radial direction 13 and towards the point of rotation of the outer rotor 11 about the rotational axis 6 is defined as the circumferential direction 14.

[0049] Next, reference is made to Figure 2 , Figure 2A longitudinal sectional view through the generator 7 is shown. The wind turbine 1 includes an air cooling system 15, which is an open system, in which air from the adjacent area 16 of the wind turbine 1 is sucked in by an air pump 18 through an inlet opening 17 of the nacelle 3. The air pump 18 is a ventilator or an air fan, respectively. The air is guided to the generator 7 to cool the inner stator 10 and the outer rotor 11. Before the air flows through the outer rotor 11 and the air gap 22, the air enters an air supply chamber 20 located on the lateral end of the outer rotor 11 and inside the housing 9. Details of the air path through the outer rotor 11 and the air gap 22 will be described below. After the air has passed through the outer rotor 11 and the air gap 22, the air is guided into an air discharge chamber 21 located inside the housing 9 and on the lateral end of the outer rotor 11. The air discharge chamber 21 is arranged opposite to the air supply chamber 20. After passing through the air discharge chamber 21, the cooling air is discharged into the adjacent area 16 via an outlet opening 19 of the nacelle 3. As an alternative to the open system, the air cooling system 15 can be a cooling circuit, in particular a cooling circuit that implements a thermodynamic cooling cycle.

[0050] Next, with reference to Figure 3 , Figure 3 a view of the generator 7 is shown that is the same as Figure 2 , in which a first possible and preferred variant of the cooling system 15 of the wind turbine 1 is shown. According to this embodiment, the air cooling system 15 is a closed system and constitutes a cooling cycle driven by an air pump 18, which is an air fan. The air cools the inner stator 10 and the outer rotor 11, wherein the air flow path is indicated by the arrows in Figure 3 . Assuming the air pump 18 as the starting point, the air enters two air supply chambers 20 that are relatively located on the lateral end of the outer rotor 11 and inside the housing 9. Then, the air flows through the outer rotor 11 and the air gap 22. Specifically, a part of the air enters the air gap 22, while another part of the cooling air enters a longitudinal recess 30 of the outer rotor 11, which will be described in more detail below. The air enters the air gap 22 and the longitudinal recess 33 from two axial sides (i.e., from the non-drive end and the drive end), such that the air flows in opposite directions. Regarding the longitudinal recess 30, the air leaves the longitudinal recess 30 through a circumferential recess 31 in the central region and enters the air gap 22. Details of the circumferential recess 31 will also be described in more detail below. Regarding the air gap 22, the air can leave the air gap 22 through a radial air passage 34 of the inner stator 10 in the central region. The radial air passage 34 is realized by a gap between laminated metal sheets 35 that constitute the inner stator 10. The radial air passage 34 is connected to the air gap 22 at one of its lateral ends and to the air discharge chamber 21 at the other end. The air discharge chamber 21 is connected to the air supply chamber 20. A heat exchanger 36 is provided inside the air discharge chamber 21 to cool the air.

[0051] Next, reference is made to Figure 4 , Figure 4 which shows the same view of the generator 7 as Figure 2 and Figure 3 , wherein a second possible and preferred variant of the cooling system 15 of the wind turbine 1 is shown. Figure 4 The system shown in Figure 3 is substantially the same as the system shown in Figure 4 , except for the aspect that the cooling system 15 shown in Figure 3 is an open system. In particular, each of the air intake chambers 20 is connected to an inlet opening 17, wherein each of the inlet openings 17 leads from the interior of the nacelle 3 or from the adjacent area 16 to the corresponding air intake chamber 20. Then, starting from the corresponding air intake chamber 20, the air flows through the outer rotor 11 and the air gap 22, as already described with respect to the system of Figure 3 . After the air has reached the air discharge chamber 21, it is guided back into the interior of the nacelle 3 or the adjacent area 16 through the outlet opening 19. The corresponding air flow is driven by an air pump 18 arranged in or on the air discharge chamber 21.

[0052] Next, reference is made to Figures 5 to 8 , Figures 5 to 8 which shows the generator 7 of the wind turbine 1 according to the first embodiment of Figure 1 . Figure 5 shows a radial cross-section through the generator 7.

[0053] Figure 6 and Figure 7 each show a longitudinal cross-section through the outer rotor 11, wherein the corresponding cutting lines are indicated by VI–VI and VII–VII in Figure 5 . Like Figure 5 , Figure 7 shows a radial cross-section through the generator 7, wherein the corresponding cutting lines are indicated by V–V and VIII–VIII in Figure 6 .

[0054] Referring to Figure 5 , the outer rotor 11 includes a hollow cylindrical rotor housing 23, wherein a plurality of magnet devices 24 are arranged on the inner surface of the rotor housing 23. The magnet devices 24 are arranged in several rows extending along the longitudinal direction 12, wherein the rows are spaced apart from each other and are evenly distributed with respect to the circumferential direction 14. Each of the magnet devices 24 includes a permanent magnet 25 attached to a substrate 26, wherein the substrate 26 is attached to the inner surface of the rotor housing 23 for attaching the corresponding magnetic device 24 to the inner surface. Each of the permanent magnets 25 is in the shape of a prism or a cube. Each of the substrates 26 is in the shape of a rectangle, wherein the sides of the substrates 26 of adjacent magnet devices 24 within one row that include the smaller length are in contact with each other.

[0055] To connect the magnet devices 24 to the inner surface of the rotor housing 23, each of the substrates 26 includes or forms a T-shaped attachment section 27. The lateral flanges of the corresponding T-shaped configuration are realized by lateral tongues 28 extending outward in the circumferential direction 14. The attachment section 27 of each of the magnet devices 24 is inserted into one of a plurality of T-shaped grooves 29 arranged on the inner surface of the rotor housing 23. A form fit is constituted between each of the attachment sections and the corresponding groove 29. The longitudinal directions of each of the attachment sections 27 and each of the grooves 29, each having a T-shaped cross-section, extend along the longitudinal direction 12.

[0056] In particular with reference to Figure 5 and Figure 6 , the inner surface of the rotor housing 23 includes a plurality of groove-shaped longitudinal recesses 30 extending along the longitudinal direction 12. That is, the longitudinal direction of the corresponding longitudinal recess 30 is parallel to the longitudinal direction 12 and the rotational axis 6. Each of the longitudinal recesses 30 is arranged on the bottom surface of one of the grooves 29.

[0057] Next, with reference to Figure 6 . It is obvious from this figure that the inner surface of the rotor housing 32 also includes groove-shaped circumferential recesses 31 extending along the circumferential direction 14. In particular, as shown by Figure 8 showing a cross-sectional view through the circumferential recess 31, it can be seen that the circumferential recess 31 connects all the longitudinal recesses 30 to the air gap 22. Therefore, the cooling air flowing from the air supply chamber 20 into the longitudinal channels 30 branches into the circumferential recess 31 in the axial middle of the outer rotor 11 and then branches into the air gap 22 to improve the cooling effect of the magnet devices 24.

[0058] Referring again to Figure 6 , it is obvious that the circumferential recess 31 is arranged at the longitudinal center of the outer rotor 11. Although the circumferential recess 31 is exactly in the middle of the longitudinal extension of the outer rotor 11, it can also be slightly offset from this position. Since the highest temperature is expected in the longitudinal middle of the outer rotor 11, the current position of the circumferential recess 31 is advantageous.

[0059] The circumferential recess 31 is a connecting recess 32 connecting at least two adjacent longitudinal recesses 30. In the present embodiment, the connecting recess 32 extends along the entire circumferential line of the inner surface of the rotor body 23 such that all the longitudinal recesses 30 are connected by the connecting recess 32.

[0060] By Figure 8It is obvious that the T-shaped shape of each of the slots 29 is interrupted in the region of the corresponding circumferential recess 31 to increase the width of the opening of the circumferential recess 31 leading to the air gap 22. The T-shaped shape of the attachment section 27 can also be interrupted in this region. For this purpose, the tongues 28 can be provided only at the longitudinal end sections of the respective magnet devices 24.

[0061] Next, referring to Figure 9 , Figure 9 shows a cross-sectional view through the rotor body 23 that is the same as Figure 6 , in which a first possible variant of the generator 7 according to the first embodiment is shown. According to this variant, several, namely three, circumferential recesses are provided. Thus, this variant differs from the variant of Figure 6 in the following feature: Two additional circumferential recesses 31 are provided, which are arranged adjacent to the circumferential recesses 31 of Figure 6 . In Figure 6 and Figure 9 , the positions where the adjacent magnet modules 24 in one of these rows contact each other are indicated by lines in the longitudinal recess 30. According to the embodiment of Figure 6 , a circumferential recess 31 is provided in the region of the magnet module 24 arranged in the center of the respective row. According to the embodiment of Figure 9 , a circumferential recess 31 is provided in the region of each of the three magnet modules 24 arranged in the center of the respective row.

[0062] Next, referring to Figure 10 , Figure 10 shows a cross-sectional view through the rotor body 23 that is the same as Figure 6 , in which a second possible variant of the electric machine 7 according to the first embodiment is shown. According to this variant, several circumferential recesses 31 are provided in the region of the magnet modules 24 arranged in the center of the respective row. According to this variant, the circumferential recesses 31 form connecting recesses 32, which are connected to the adjacent longitudinal recesses 30 in pairs with each other. Specifically, two sets of connecting recesses 31 are provided, and the circumferential recesses 31 in each of these sets extend along a common circumferential line. These circumferential lines are arranged in the longitudinal center of the outer rotor 11. These circumferential lines are at the same distance from the central circumferential line. The circumferential recesses 31 in these two sets are alternating with respect to their longitudinal positions.

[0063] Figure 11 shows a third possible variant of the generator 7 according to the first embodiment. This variant is similar to the variant of Figure 10 , wherein the difference is that, in addition to the two sets of connecting recesses 31, two additional sets of connecting recesses 31 are provided on each lateral side. Thus, six sets of connecting recesses 31 are provided, and the circumferential recesses 31 in each of these sets extend along a common circumferential line. The circumferential recesses 31 in two adjacent sets are alternating with respect to their longitudinal positions.

[0064] Next, referring to Figure 12 and Figure 13 , Figure 12 and Figure 13 show the generator 7 of the wind turbine 1 according to the second embodiment. Figure 1 of the wind turbine 1. Figure 12 and Figure 13 show cross-sectional views of the generator 7 that are the same as Figure 8 and Figure 6 . The second embodiment differs from the first embodiment in the following aspect: Instead of one circumferential recess 31 that is a connecting recess 32, a plurality of circumferential recesses 31 that are non-connecting recesses 33 are provided. The non-connecting recesses 33 are arranged collinearly along the central circumferential line. In contrast to the connecting recess 32, each of the non-connecting recesses 33 connects only one of the longitudinal recesses 30 to the air gap 22, i.e., does not connect to other longitudinal recesses 30.

[0065] Figure 14 , Figure 15 and Figure 16 show the first, second, and third variants of the generator 7 according to the second embodiment. These variants correspond to the first, second, and third variants of the generator 7 according to the first embodiment. That is, Figure 14 the variant shown in Figure 9 corresponds to the variant shown in Figure 15 corresponds to the variant shown in Figure 10 , and Figure 16 the variant shown in Figure 11 corresponds to the variant shown in

[0066] Figures 17 to 20 show other variants of the generator 7 according to the second embodiment. Figure 17 the variant shown in Figure 13 corresponds to the embodiment shown in Figure 13 . According to Figure 17 shows that a set of circumferential recesses 31 can be provided, where this set is arranged at the longitudinal center of the outer rotor 11. Specifically, each longitudinal recess 30 provides two circumferential recesses 31, and the circumferential recesses 31 that are non-connecting recesses 33 are arranged longitudinally offset and laterally opposite on both sides of the corresponding longitudinal recess 30.

[0067] Figure 18 the variant shown in Figure 17An embodiment is provided where the same set of circumferential recesses 31 is provided as a central group. In addition to this central group, two additional groups equivalent to this central group are provided, that is, referring to the longitudinal direction 12, one additional group is before this central group, and one additional group is after this central group.

[0068] Figure 19 The variant shown in Figure 13 corresponds to the embodiment of Figure 13 The embodiment of

[0069] Next, an optional aspect of the present utility model is explained with the aid of the embodiment of Figure 19 According to this aspect, several circumferential recesses 31 with different cross-sectional areas are provided. The cross-sectional area is rectangular and has a specific width extending along the longitudinal direction 12 and a height extending along the radial direction 13. The circumferential recess 31 arranged at the longitudinal center of the outer rotor 11 has a larger cross-sectional area than the circumferential recess 31. Specifically, the farther the corresponding circumferential recess 31 is from the longitudinal center, the smaller its cross-sectional area, so that the largest amount of air flows through the circumferential recess 31 arranged at the longitudinal center, because there, usually the highest cooling efficiency is required.

[0070] In addition to Figure 20 the aspect which is the three-dimensional view of the recesses 30, 31, Figure 20 shows the same view as Figures 13 to 19 where other parts of the outer rotor 11 are omitted. Figure 20 The variant shown in Figure 17 corresponds to the embodiment of Figure 17 For the embodiment of Figure 20 although for each longitudinal recess 30, two circumferential recesses 31 are provided, and these two circumferential recesses 31 are arranged laterally opposite with a longitudinal offset on both sides of the corresponding longitudinal recess 30; however, according to the embodiment of Figure 20 each longitudinal recess 30 provides two pairs of circumferential recesses 31, and these two pairs of circumferential recesses 31 are arranged laterally opposite with a longitudinal offset on both sides of the corresponding longitudinal recess 30. Although this is not shown in

[0071] These multiple embodiments show that with respect to the recesses 30, 31, the designer is free to distribute the circumferential recess 31 according to specific requirements. There can be a uniform or non-uniform distribution of the circumferential recess 31 with respect to the longitudinal direction 12. Additionally, one or several circumferential recesses 31 can be provided below each, especially below the central magnet module 24.

[0072] Although the present invention has been described in detail with reference to the preferred embodiments, the present invention is not limited by the disclosed examples, and those skilled in the art can derive other variations without departing from the scope of the present invention according to the disclosed examples.

[0073] Regardless of the usage of grammatical terms, individuals with male or female identities are included within the term.

Claims

1. A generator for a wind turbine (1), comprising an inner stator (10) and an outer rotor (11), the outer rotor (11) being rotatably mounted about a rotational axis (6) extending along a longitudinal direction (12) of the outer rotor (11), wherein an air gap (22) is provided between the inner stator (10) and the outer rotor (11), wherein the outer rotor (11) comprises a hollow cylindrical rotor housing (23) and a plurality of magnet devices (24), the magnet devices (24) being arranged in a plurality of rows extending along the longitudinal direction (12) at an inner surface of the rotor housing (23), wherein the inner surface comprises at least one groove-shaped longitudinal recess (30), the groove-shaped longitudinal recess (30) extending along the longitudinal direction (12) and being covered by the magnet devices (24) in one of the rows, characterized in that, The inner surface includes at least one groove-shaped circumferential recess (31) which extends along the circumferential direction (14) and connects the longitudinal recess (30) with the air gap (22).

2. The generator according to claim 1, wherein One of the circumferential recesses (31) or the circumferential recesses (31) is a central recess arranged at the longitudinal center of the outer rotor (11).

3. The generator according to claim 1, wherein, At least one of the circumferential recesses (31) or the circumferential recesses (31) is a connecting recess (32) which connects at least two adjacent longitudinal recesses (30) to each other.

4. The generator according to claim 1, characterized in that, At least one of the circumferential recesses (31) or the circumferential recesses (31) is a non-connecting recess (33) which only connects one of the longitudinal recesses (30) or the longitudinal recesses (30) with the air gap (22).

5. The generator according to claim 3 or 4, characterized in that, Arrays of connecting recesses (32) and / or non-connecting recesses (33) are provided, wherein the circumferential recesses (31) in each group of the groups extend along a common circumferential line, wherein the circumferential lines of the groups are arranged along the longitudinal direction (12), and wherein the circumferential recesses (31) in two adjacent groups are alternating.

6. The generator according to one of claims 1 to 4, characterized in that, At least one of the magnet devices (24) includes a permanent magnet (25) located on a substrate (26), wherein the substrate (26) is attached to the rotor housing (23) for arranging this magnet device (24) on the inner surface.

7. The generator according to any one of claims 1 to 4, characterized in that At least one of the magnet devices (24) includes a T-shaped attachment section (27), wherein the rotor housing (23) includes a T-shaped groove (29) on the inner surface, and wherein the attachment section (27) is inserted into the groove (29) to attach the magnet device (24) to the rotor housing (23).

8. The generator according to claim 7, characterized in that, The T-shaped shape of the attachment section (27) and / or the groove (29) is interrupted in the region of at least one of the circumferential recesses (31) or the circumferential recesses (31).

9. The generator according to one of claims 1 to 4, characterized in that, At least two of the rows are spaced apart from each other with respect to the circumferential direction (14).

10. The generator according to claim 9, characterized in that, The rows are evenly distributed with respect to the circumferential direction (14).

11. The generator according to one of claims 1 to 4, characterized in that, The adjacent magnet devices (24) in at least one of the rows are in contact with each other.

12. The generator according to one of claims 1 to 4, characterized in that, Several circumferential recesses (31) with different cross-sectional areas are provided.

13. The generator according to claim 6, characterized in that, The substrate (26) of at least one of the magnet devices (24) includes a T-shaped attachment section (27), wherein the rotor housing (23) includes a T-shaped groove (29) on the inner surface, and wherein the attachment section (27) is inserted into the groove (29) to attach the magnet device (24) to the rotor housing (23).

14. The generator according to claim 7, characterized in that, The substrate (26) of at least one of the magnet devices (24) includes a T-shaped attachment section (27), wherein the rotor housing (23) includes a T-shaped groove (29) on the inner surface, and wherein the attachment section (27) is inserted into the groove (29) to attach the magnet device (24) to the rotor housing (23).

15. An outer rotor (11) for a generator (7) of a wind turbine (1), comprising a hollow cylindrical rotor housing (23) and a plurality of magnet devices (24), the magnet devices (24) being arranged at the inner surface of the rotor housing (23) in a plurality of rows extending along a longitudinal direction (12), wherein the inner surface comprises at least one groove-shaped longitudinal recess (30) which extends along the longitudinal direction (12) and is covered by the magnet devices (24) in one of the rows, characterized in that, The inner surface includes at least one groove-shaped circumferential recess (31) extending along a circumferential direction (14), wherein, with respect to the state in which the outer rotor (11) is mounted in the generator (7), the at least one groove-shaped circumferential recess (31) connects the longitudinal recess (30) to an air gap (22) provided between an inner stator (10) and the outer rotor (11) of the generator (7).

16. A wind turbine, characterized in that, The wind turbine includes a generator (7) according to one of claims 1 to 14.

17. The wind turbine according to claim 16, characterized in that, The air cooling system (15) is a cooling circuit or an open system and includes at least one air pump (18), wherein the air pump (18) is adapted to pump cooling air to the air gap (22) and / or the longitudinal recess (30).

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