Rotary electric machine and vehicle provided with same

Abstract

The purpose of the present invention is to provide a rotary electric machine having improved cooling performance.　A rotor core 7 constituting a rotor 2 of the present invention is provided with: a plurality of axial ducts 18 penetrating the rotor 2 in the axial direction and formed along the circumferential direction at positions on the radial inner side of field coils 12; a magnetic pole part 24 positioned between the field coils 12 adjacent to each other in the circumferential direction; and a plurality of rotor-side intermediate ducts extending radially outward from the radial inner side of the rotor 2. The rotor-side intermediate duct is provided with: a rotor-side first intermediate duct 21a, the radially inner tip of which is positioned radially outward of the radial outer end of the axial duct (18); and a rotor-side second intermediate duct 21b, the radial length of which is longer than that of the rotor-side first intermediate duct 21a. The rotor-side first intermediate duct 21a is disposed at the circumferential end of the magnetic pole part 24.

Description

Rotating electric machine and vehicle equipped with the same

[0001] The present invention relates to a rotating electric machine and a vehicle equipped with the same.

[0002] In recent years, efforts have been made to improve the efficiency of rotating electrical machines in order to reduce CO2 emissions. Furthermore, for rotating electrical machines used in vehicles such as automobiles and trains, miniaturization and weight reduction are also required in addition to high efficiency. By reducing the weight of rotating electrical machines, the vehicle body itself can be made lighter, improving fuel efficiency and ultimately leading to improved efficiency of the automobile and train systems.

[0003] Rotating electric machines used to supply power to railway vehicles, construction vehicles, etc. have two power systems: one power supply (for traction) to drive the vehicle body, and one auxiliary power supply for other accessories. Because these two systems have completely different uses, their capacities and electrical characteristics are completely different. For this reason, two rotating electric machines with different capacities are placed inside the frame of the rotating electric machine, and the two rotors are arranged side by side on the same rotating shaft.

[0004] Generally, there is a trade-off between compactness and weight reduction and the efficiency of rotating electrical machines. Therefore, prioritizing compactness and weight reduction results in a decrease in the efficiency of the rotating electrical machine. This means that losses increase. In other words, increasing power density also increases heat generation density. Therefore, improving cooling performance is essential to achieving compactness and weight reduction as a viable rotating electrical machine. While various cooling methods for rotating electrical machines exist, the axial open-flow cooling method offers a simple structure and high cooling performance. This structure directly connects the inside of the rotating electrical machine with the outside (outside air). The refrigerant (air) used to cool the rotating electrical machine can be obtained by a self-cooling fan mounted on the rotating shaft within the rotating electrical machine or by an electric blower installed separately from the rotating electrical machine. In particular, when cooling is required even while the rotating electrical machine is stopped, a method is used in which the refrigerant is forced to flow through the rotating electrical machine using an electric blower (forced draft).

[0005] Furthermore, to increase the airflow inside the rotating electric machine and improve the cooling effect, an intermediate duct is arranged in the axial direction of the rotating electric machine. The electromagnetic section of the rotating electric machine is constructed by stacking electromagnetic steel sheets, with the stacked electromagnetic steel sheets and intermediate ducts arranged alternately in the axial direction. By providing this intermediate duct, the fan action (oiler head pressure) caused by the rotation of the rotor is taken into account, increasing the overall refrigerant flow rate. Furthermore, the field coil and stator coil are directly exposed to the refrigerant, improving the temperature reduction effect. For this reason, cooling methods for rotating electric machines equipped with intermediate ducts have been studied, and a technology such as that described in Patent Document 1 has been proposed.

[0006] Patent Document 1 describes a rotating electric machine equipped with an intermediate duct that extends radially outward from a rotor. The intermediate ducts in Patent Document 1 are multiple ducts of the same shape that are arranged at equal intervals in the circumferential direction.

[0007] Japanese Patent Application Laid-Open No. 2021-72714

[0008] In Patent Document 1, an air hole (axial duct) is provided on the inner diameter of the rotor. This air hole allows a blower or fan to ventilate the refrigerant in the axial direction. The air hole is located on an extension of the radially inner side (inner circumferential side) of the field coil. An intermediate duct that guides the refrigerant to the field coil is located across the air hole. The refrigerant flowing in from the air hole is ventilated radially through the intermediate duct due to the fan action described above. However, most of the air passage is limited to the area where the field coil is located, and almost no air flows into the magnetic pole section (area where the field coil is not located). This is a structure unique to cylindrical synchronous rotating electric machines, where the field coil section and the magnetic pole section are alternately arranged in the circumferential direction, and the intermediate duct is configured as described in Patent Document 1. The refrigerant passage in the radial direction of the rotor is the gap between the field coil and the intermediate duct. Because this gap is narrow, air flow resistance is excessive, reducing the amount of refrigerant flowing into the gap and the overall air volume.

[0009] An object of the present invention is to provide a rotating electric machine with improved cooling performance and a vehicle equipped with the same.

[0010] In order to achieve the above object, the present invention provides a rotating electric machine including a rotor in which field coils are wound in slots in a rotor core, and a stator disposed radially outside the rotor with a gap provided and having a stator coil wound around the stator core, wherein the rotor core has a plurality of voids formed along the circumferential direction at positions radially inside the field coils and a bridge portion located radially outside the voids and connecting adjacent voids, and a bridge portion located radially outside the circumferential direction and connecting adjacent voids between the field coils. and a plurality of rotor-side intermediate ducts extending from the radially inner side of the rotor toward the radially outer side and forming rotor-side ventilation passages through which the refrigerant flows between the field coil and the magnetic pole portion, wherein the rotor-side intermediate ducts include a rotor-side first intermediate duct whose radially inner tip is located radially outward of the radially outer end of the hole portion, and a rotor-side second intermediate duct whose radial length is longer than the rotor-side first intermediate duct, and the rotor-side first intermediate duct is disposed at the circumferential end of the magnetic pole portion.

[0011] According to the present invention, it is possible to provide a rotating electric machine with improved cooling performance and a vehicle equipped with the same.

[0012] FIG. 1 is a cross-sectional view taken along the axial direction of a rotating electric machine according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II' in FIG. 1. FIG. 3 is an enlarged view of a radially inner end of a rotor-side first intermediate duct 21a according to a first embodiment of the present invention. FIG. 4 is a cross-sectional view of two poles of a rotor 2 and a stator 3 according to a second embodiment of the present invention. FIG. 5 is a cross-sectional view of two poles of a rotor 2 according to a third embodiment of the present invention. FIG. 6 is a cross-sectional view of two poles of a rotor 2 according to a fourth embodiment of the present invention. FIG. 7 is a cross-sectional view of two poles of a rotor 2 according to a fifth embodiment of the present invention. FIG. 8 is a diagram showing a schematic configuration of a vehicle equipped with a rotating electric machine according to a sixth embodiment of the present invention.

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In principle, identical elements are designated by the same reference numerals in all drawings. Furthermore, descriptions of parts having identical functions will be omitted. Note that the configurations described below are merely examples, and it is not intended that the embodiments of the present invention be limited to the specific embodiments below.

[0014] FIG. 1 is a cross-sectional view of a rotating electric machine according to a first embodiment of the present invention, cut along the axial direction. FIG. 2 is a cross-sectional view taken along line II-II' in FIG. 1. FIG. 2 shows a cross section of two poles of a rotor 2 and a stator 3 in a rotating electric machine 100. The rotating electric machine of this embodiment is a rotating electric machine that is mainly used in connection with an engine. It has an output of several thousand kVA, a voltage of several kV, and a rotational speed of several thousand min-1, and is used as a power source for vehicles such as large dump trucks and railway cars.

[0015] As shown in Fig. 1, the rotating electric machine 100 includes a rotor 2 and a stator 3 disposed radially outward (on the outer periphery) of the rotor 2 and fixed to a frame 1. The frame 1 is provided with bearings 4 for rotating the rotor 2. In Fig. 1, since the rotor 2 is connected to an engine as described above, the side without the bearing 4 is supported by a bearing on the engine side. Of course, bearings 4 may be provided on both sides of the rotating electric machine 100.

[0016] The configuration of the rotor 2 will be described. The rotor 2 has a shaft 5 rotatably supported by bearings 4 and fastened to it. A field coil 12 is wound in slots in a rotor core 7, with field coil ends 6 of the field coil 12 protruding from both axial ends of the rotor core 7. Rotor core clamps 8 are provided at both axial ends of the rotor core 7 to apply surface pressure from the axial direction and maintain the pressed state of the electromagnetic steel sheets. A cylindrical damper bar 15 is provided between adjacent slots (field coils 12) in the rotor core 7. A rotor wedge 16 is provided on the radially outer side (outer periphery) of the field coil 12 to prevent the field coil 12 from slipping out of the slot. Furthermore, a stator 3 is provided on the radially outer side (outer periphery) of the rotor 2 via a gap 14.

[0017] The configuration of the stator 3 will now be described. A stator coil 13 is wound around a stator core 9 of the stator 3, with stator coil ends 10 protruding from both axial ends of the stator core 9. Both axial ends of the stator core 9 are provided with stator core clamps 11 for applying surface pressure from the axial direction and maintaining the pressed state of the electromagnetic steel sheets. A stator wedge 17 is provided on the radially inner side (inner peripheral side) of the stator coil 13 to prevent the stator coil 13 from slipping out.

[0018] Next, the cooling structure of the rotating electrical machine 100 will be described.

[0019] Axial ducts 18 (holes) are provided on the radially inner side (inner peripheral side) of the rotor core 7, penetrating in the axial direction and allowing refrigerant 20 (air) to circulate in the axial direction. A plurality of axial ducts 18 are provided along the circumferential direction of the rotor 2, positioned on extensions of the radially inner sides of the field coils 12. Bridge portions 25 (see FIG. 4 ) connecting adjacent axial ducts 18 are formed between adjacent axial ducts 18, and magnetic pole portions 24 are located radially outward of the bridge portions 25, where no field coil 12 of the rotor core 7 is disposed. The field coils 12 and the magnetic pole portions 24 are alternately arranged in the circumferential direction of the rotor 2. In other words, the magnetic pole portions 24 are located between adjacent field coils 12 in the circumferential direction.

[0020] The rotor core 7 is also provided with a plurality of rotor-side intermediate ducts (rotor-side first intermediate duct 21 a, rotor-side second intermediate duct 21 b) that protrude axially from the surface of the rotor core 7, extend radially from the radial inside to the radial outside, and form ventilation paths through which the refrigerant 20 flows to the field coil 12 and the magnetic pole portions 24. The rotor-side first intermediate duct 21 a and the rotor-side second intermediate duct 21 b are fixed to the surface of the rotor core 7 by welding or the like. The rotor-side first intermediate duct 21 a and the rotor-side second intermediate duct 21 b are arranged between the slots around which the field coil 12 is wound and at the magnetic pole portions 24. The rotor-side first intermediate duct 21 a and the rotor-side second intermediate duct 21 b have a rectangular shape when viewed from the radial inside or when cut circumferentially.

[0021] The rotor-side first intermediate duct 21 a is formed to have a shorter radial length than the rotor-side second intermediate duct 21 b. In other words, the rotor-side second intermediate duct 21 b is formed to have a longer radial length than the rotor-side first intermediate duct 21 a.

[0022] The rotor-side coil section first intermediate duct 21a1 is disposed between adjacent slots in the circumferential direction. The radially inner tip of the rotor-side coil section first intermediate duct 21a1 is located radially outward of the radially outer end 18a of the axial duct 18. In other words, the rotor-side coil section first intermediate duct 21a1 is formed to extend from a position radially outward of the axial duct 18 to a position radially outward of the rotor core 7 so as not to overlap with the axial duct 18.

[0023] The rotor-side magnetic pole portion first intermediate duct 21a2 is disposed between adjacent field coils 12 in the circumferential direction and at the circumferential end of the magnetic pole portion 24. Like the rotor-side coil portion first intermediate duct 21a1, the rotor-side magnetic pole portion first intermediate duct 21a2 is formed to have a shorter radial length than the rotor-side second intermediate duct 21b. Furthermore, the radially inner tip of the rotor-side magnetic pole portion first intermediate duct 21a2 is located radially outward of the radially outer end 18a of the axial duct 18.

[0024] The rotor core 7 is provided with a rotor-side ventilation passage formed by the rotor-side first intermediate duct 21 a and the rotor-side second intermediate duct 21 b. The ventilation passage is composed of a rotor-side field coil ventilation passage 22 a, through which the refrigerant discharged from the axial duct 18 flows to the field coil 12, and a rotor-side magnetic pole portion ventilation passage 22 b, through which the refrigerant discharged from the axial duct 18 flows to the magnetic pole portion 24.

[0025] The rotor side coil portion first intermediate duct 21 a 1 arranged between the slots forms a part of the rotor side field coil ventilation passage 22 a through which air flows to the field coil 12 .

[0026] The rotor side magnetic pole portion first intermediate duct 21a2, which is arranged at the circumferential end of the magnetic pole portion 24, forms a part of the rotor side field coil ventilation passage 22a that flows to the field coil 12, and a part of the rotor side magnetic pole portion ventilation passage 22b that flows to the magnetic pole portion 24.

[0027] The rotor core 7 is configured by laminating a plurality of electromagnetic steel plates in the axial direction, and the open sides of the rotor-side field coil ventilation passage 22 a and the rotor-side magnetic pole portion ventilation passage 22 b are covered by electromagnetic steel plates that are axially adjacent to the electromagnetic steel plates to which the rotor-side first intermediate duct 21 a and the rotor-side second intermediate duct 21 b are fixed. The number of rotor-side intermediate ducts is not limited to one, and a plurality of rotor-side intermediate ducts may be provided in the axial direction of the rotor core 7.

[0028] The rotor-side second intermediate duct 21b is disposed so as to pass between adjacent axial ducts 18 (bridge portions 25) and through the magnetic pole portions 24, and extend from a position at the center (radially inner side) of the rotor core 7 to a position at the radial outer side of the rotor core 7. The rotor-side second intermediate duct 21b is disposed from the bridge portions 25 to the magnetic pole portions 24. A portion of the rotor-side second intermediate duct 21b is disposed so as to overlap (straddle) the axial duct 18.

[0029] The stator core 9 is fixed to a frame 1 disposed radially outside the stator core 9. A back duct 19 communicating in the axial direction is formed between the radially outside of the stator core 9 and the frame 1. The stator core 9 also has a plurality of stator-side intermediate ducts 31 that protrude axially from the surface of the stator core 9 and extend radially from the radially inner side to the radially outer side. The stator-side intermediate ducts 31 are fixed to the surface of the stator core 9 by welding or the like. The stator-side intermediate ducts 31 are arranged to pass between adjacent stator coils 13. The stator-side intermediate ducts 31 have a rectangular shape when viewed from the radially inner side or when cut circumferentially. The stator core 9 has a stator-side ventilation passage 23 formed by the stator-side intermediate ducts 31. The stator core 9 is configured by laminating multiple electromagnetic steel plates, and the open side of the stator side intermediate duct 31 is covered by an electromagnetic steel plate adjacent to the electromagnetic steel plate to which the stator side intermediate duct 31 is fixed. The number of stator side intermediate ducts 31 is not limited to one, and multiple stator side intermediate ducts 31 may be provided in the axial direction of the stator core 9. The rotor side intermediate duct and the stator side intermediate duct 31 are preferably positioned in the same axial direction.

[0030] Next, the flow of the refrigerant will be described. The arrows in Figures 1 and 2 indicate the flow of the refrigerant 20. When the refrigerant 20 flows in through the opening 1a of the frame 1, it branches off and flows through the rear duct 19, the gap 14, and the axial duct 18. The refrigerant 20 that flows into the axial duct 18 is discharged radially outward by fan action caused by the rotation of the rotor 2, and flows through the rotor-side field coil ventilation passage 22a and the rotor-side magnetic pole portion ventilation passage 22b formed by the rotor-side first intermediate duct 21a and the rotor-side second intermediate duct 21b.

[0031] The refrigerant 20 that flows through the rotor-side field coil ventilation passage 22a and the rotor-side magnetic pole portion ventilation passage 22b flows into the stator-side ventilation passage 23 formed by the gap 14 and the stator-side intermediate duct 31. Because the stator-side ventilation passage 23 is connected to the rear duct 19, the refrigerant 20 that flows through the stator-side ventilation passage 23 flows into the rear duct 19. The refrigerant 20 that flows into the rear duct 19, the gap 14, and the axial duct 18 flows in the axial direction and is released to the atmosphere. The refrigerant 20 that flows through the rear duct 19 and the stator-side ventilation passage 23 reduces temperature increases mainly due to iron loss generated in the stator core 9 and copper loss generated in the stator coil 13. The refrigerant 20 that flows through the gap 14 reduces temperature increases mainly due to iron loss generated in the stator core 9, copper loss generated in the stator coil 13, and copper loss generated in the field coil 12. The refrigerant 20 flowing through the axial duct 18, the rotor side field coil ventilation passage 22a, and the rotor side magnetic pole portion ventilation passage 22b reduces the temperature rise caused mainly by iron loss occurring in the rotor core 7 and copper loss occurring in the field coil 12.

[0032] In a rotating electric machine 100 that is compact and lightweight, the current density of the stator coil 13 is higher than the current density of the field coil 12. That is, when comparing the coil temperatures, the temperature of the stator coil 13 is higher than that of the field coil 12. For this reason, it is necessary to actively cool the stator coil 13. To reduce the temperature of the stator coil 13, it is effective to increase the flow rate of the refrigerant 20 flowing through the rear duct 19, the gap 14, and the stator-side ventilation passage 23, as described above. Increasing the refrigerant flow rate requires increasing the diameter of the fan and the capacity of the blower, but this poses the problem of increasing the size of the rotating electric machine and the blower. Effectively utilizing the refrigerant flow rate by fan action is an effective method for increasing the refrigerant flow rate without being affected by these factors.

[0033] Therefore, in this embodiment, the flow rate of the refrigerant 20 flowing through the magnetic pole portion 24 is increased to increase the flow rate of the refrigerant 20 flowing through the stator-side ventilation passage 23. To achieve this, in this embodiment, the radial length of the rotor-side magnetic pole portion first intermediate duct 21a2 located at the circumferential end of the magnetic pole portion 24 is made shorter than that of the second intermediate duct 21b, and further, the radially inner tip end of the rotor-side magnetic pole portion first intermediate duct 21a2 is positioned radially outward from the radially outer end 18a of the axial duct 18.

[0034] With this configuration, the refrigerant 20 discharged from the axial duct 18 passes through the rotor-side magnetic pole portion ventilation passage 22b and easily flows into the magnetic pole portion 24 due to the effect of fan action.

[0035] Furthermore, because the ventilation passage area of ​​rotor-side magnetic pole portion ventilation passage 22b of magnetic pole portion 24 is larger than that of rotor-side field coil ventilation passage 22a where field coil 12 is located, the refrigerant easily flows through gap 14 and stator-side ventilation passage 23. In other words, because magnetic pole portion 24 does not have field coil 12, it can be actively used as a ventilation passage for refrigerant 20. The only type of rotating electric machine that can achieve this configuration is a cylindrical synchronous rotating electric machine in which field coil 12 is wound in a concentrated manner around magnetic pole portion 24.

[0036] According to this embodiment, the total refrigerant flow rate can be increased by 1.2 times, and the cooling performance of the rotating electrical machine can be improved.

[0037] Furthermore, it is preferable that the circumferential widths of the rotor-side intermediate ducts (rotor-side first intermediate duct 21 a, rotor-side second intermediate duct 21 b) and the stator-side intermediate duct 31 be smaller than the diameter of the damper bar 15. Since the damper bar 15 is a component located at the connection portion (gap 14, rotor-side field coil ventilation passage 22 a, rotor-side magnetic pole portion ventilation passage 22 b) of the refrigerant 20 flowing radially from the rotor 2, from the viewpoint of ensuring the ventilation passage area, by making the rotor-side intermediate ducts (rotor-side first intermediate duct 21 a, rotor-side second intermediate duct 21 b) and the stator-side intermediate duct 31 smaller than the diameter of the damper bar 15, it is possible to increase the passage area of ​​most of the ducts.

[0038] Next, the configuration of the rotor-side intermediate duct and the stator-side intermediate duct will be described. Fig. 3 is an enlarged view of the radially inner end of the rotor-side first intermediate duct 21a according to the first embodiment of the present invention. Note that Fig. 3 describes the rotor-side first intermediate duct 21a, but the rotor-side second intermediate duct 21b and the stator-side intermediate duct 31 are also similar.

[0039] 3, the radially inner end 26 of the rotor-side first intermediate duct 21 a is formed in an arc shape. The refrigerant 20 discharged from the axial duct 18 collides with the radially inner end 26 of the rotor-side first intermediate duct 21 a. However, because the radially inner end 26 is formed in an arc shape, pressure loss at the inlet of the refrigerant 20 can be reduced, and the refrigerant flow rate can be increased.

[0040] In addition, it is effective from the viewpoint of the ease of flow of the refrigerant 20 to arrange the axial positional relationship of the intermediate ducts (rotor-side first intermediate duct 21a, rotor-side second intermediate duct 21b, and stator-side intermediate duct 31) arranged on the rotor 2 and stator 3 so that they are arranged at the same pitch as shown in FIG.

[0041] Although the rotating electric machine 100 shown in this embodiment has 10 poles and 90 slots in the stator 3, other numbers of poles and slots may be used. Also, although the number of stages of the intermediate ducts arranged in the axial direction (the rotor-side first intermediate duct 21a, the rotor-side second intermediate duct 21b, and the stator-side intermediate duct 31) is one, multiple stages may be used.

[0042] Furthermore, in this embodiment, all of the intermediate ducts (the rotor-side first intermediate duct 21a, the rotor-side second intermediate duct 21b, and the stator-side intermediate duct 31) are crank-shaped in consideration of productivity. The intermediate ducts are joined to the electromagnetic steel plates by spot welding, and by making the intermediate ducts crank-shaped, they can easily stand on their own (are less likely to tip over) when joined. Of course, the intermediate ducts may also be linear.

[0043] Next, a second embodiment will be described with reference to Fig. 4. Fig. 4 is a cross-sectional view of two poles of a rotor 2 and a stator 3 according to the second embodiment of the present invention. The same reference numerals are used to designate components common to the first embodiment, and detailed descriptions thereof will be omitted.

[0044] As explained in the first embodiment, the rotor core 7 and the stator core 9 are made by laminating electromagnetic steel sheets, so it is necessary to apply a surface pressure from the axial direction to ensure rigidity. The larger the contact area with the electromagnetic steel sheets, the higher the rigidity that can be obtained by the surface pressure.

[0045] When intermediate ducts (rotor-side first intermediate duct 21a, rotor-side second intermediate duct 21b, stator-side intermediate duct 31) are arranged on the rotor core 7 and the stator core 9 as in this embodiment, the contact surfaces of the intermediate ducts and the electromagnetic steel sheets become the areas that receive surface pressure. Therefore, reducing the number of intermediate ducts reduces the contact surface with the electromagnetic steel sheets, leading to a decrease in the rigidity of the rotor core 7 and the stator core 9. In particular, the rotor 2, being a rotating body, requires more rigidity than the stator 3 to ensure reliability.

[0046] 4, in this embodiment, as a configuration that satisfies both cooling performance and rigidity, the rotor-side second intermediate duct 21b is arranged in the bridge portion 25 that connects adjacent axial ducts 18, and the rotor-side first intermediate duct 21a, which is shorter than the rotor-side second intermediate duct 21b, is arranged in the other portions. In this embodiment, in one region extending from the bridge portion 25 to the magnetic pole portion 24, a plurality of rotor-side second intermediate ducts 21b, each having a radial length longer than the rotor-side first intermediate duct 21a, are provided.

[0047] Furthermore, in the first embodiment, the rotor-side second intermediate duct 21b was arranged so that a portion thereof overlapped (straddled) the axial duct 18, but in the present embodiment, the intermediate duct is arranged so as not to overlap with the axial duct 18. That is, the rotor-side first intermediate duct 21a, which is arranged radially outside the circumferential range in which the axial duct 18 is formed and in the circumferential region in which the field coil 12 is arranged, has its radially inner tip positioned radially outside the radially outer end 18a of the axial duct 18. The rotor-side field coil ventilation passage 22a, which flows the refrigerant 20 to the field coil 12, is composed only of the rotor-side first intermediate duct 21a.

[0048] Although the field coil 12 generates less heat than the stator coil 13, it is still necessary to cool the field coil 12. A plurality of field coils 12 are arranged radially outside the axial duct 18. To efficiently cool the plurality of field coils 12, the refrigerant 20 must be circulated evenly toward the plurality of field coils 12. In this embodiment, the radially inner tip of the rotor-side first intermediate duct 21a is positioned radially outward of the radially outer end 18a of the axial duct 18. This allows the refrigerant 20 discharged from the axial duct 18 to flow evenly through the plurality of field coils 12, thereby improving the cooling performance of the field coils 12. Furthermore, the axial duct 18 does not include any components that create ventilation resistance for the refrigerant 20 discharged from the axial duct 18. This increases the flow rate of the refrigerant 20, thereby improving the cooling performance of the field coils 12.

[0049] Furthermore, the refrigerant 20 discharged from the axial duct 18 may contain dust. If an intermediate duct is arranged so as to straddle the axial duct 18, there is a possibility that dust contained in the refrigerant 20 may adhere to the intermediate duct. For this reason, in a configuration in which an intermediate duct is arranged so as to straddle the axial duct 18, maintenance is required to remove dust that has adhered to the intermediate duct. In this embodiment, there is no intermediate duct straddling the axial duct 18, so the time required for maintenance can be reduced.

[0050] Next, a third embodiment will be described with reference to Fig. 5. Fig. 5 is a cross-sectional view of two poles of a rotor 2 according to a third embodiment of the present invention. The same reference numerals are used to designate components common to the first and second embodiments, and detailed descriptions thereof will be omitted.

[0051] In this embodiment, a thick portion 210 having a thickened (widened) circumferential width is provided on the radially inner side of the rotor-side second intermediate duct 21 b. The thick portion 210 is provided on the rotor-side second intermediate duct 21 b located radially inner than the axial duct 18.

[0052] In this embodiment, multiple rotor-side intermediate ducts (rotor-side first intermediate duct 21a, rotor-side second intermediate duct 21b) are arranged on the rotor core 7, but the contact area with the electromagnetic steel sheet differs between the radially inner and radially outer sides. In FIG. 5 , the contact area between the intermediate duct and the electromagnetic steel sheet is larger radially outer than the axial duct 18 than the radially inner side. This is because there are more intermediate ducts at positions radially outer than the axial duct 18. To apply surface pressure evenly in the axial direction, it is important to minimize differences in contact area. Therefore, in this embodiment, the rotor-side second intermediate duct 21b, which is located radially inner than the axial duct 18, is provided with a thick portion 210 with a thickened (widened) circumferential width, thereby increasing the contact area between the intermediate duct and the electromagnetic steel sheet radially inner than the axial duct 18. Furthermore, according to this embodiment, by applying a surface pressure to the rotor core 7 more uniformly in the axial direction, the reliability of the rotor 2 can be improved.

[0053] Next, a fourth embodiment will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view of two poles of a rotor 2 according to a fourth embodiment of the present invention. The same reference numerals are used to designate components common to the first to third embodiments, and detailed descriptions thereof will be omitted.

[0054] In Example 3, a thick portion 210 with a thicker (wider) circumferential width is provided in the rotor side second intermediate duct 21b to increase the contact area between the intermediate duct and the electromagnetic steel plate radially inward of the axial duct 18, but in Example 4, the intermediate duct is divided and arranged radially.

[0055] In this embodiment, the intermediate ducts are divided into a radially inner side and a radially outer side, with the axial duct 18 as the boundary. That is, the rotor-side first intermediate duct 21a is arranged radially outer than the axial duct 18, and the rotor-inner-diameter-side intermediate duct 211 is arranged radially inner than the axial duct 18. The rotor-inner-diameter-side intermediate duct 211 is arranged on an extension of the radially inner side of the rotor-side first intermediate duct 21a. Furthermore, in this embodiment, the intermediate ducts do not overlap with the axial duct 18. With this configuration, it is possible to obtain the same effects as in the third embodiment.

[0056] Also, although not shown, the circumferential width of the rotor inner diameter side intermediate duct 211 may be made thicker (wider) than the circumferential width of the rotor side first intermediate duct 21a, thereby increasing the contact area between the rotor inner diameter side intermediate duct 211 and the electromagnetic steel plate.

[0057] Next, a fifth embodiment will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view of two poles of a rotor 2 according to a fifth embodiment of the present invention. The same reference numerals are used to designate components common to the first to fourth embodiments, and detailed descriptions thereof will be omitted.

[0058] In the fifth embodiment, an annular intermediate duct 212 is disposed radially inside the axial duct 18 so as to be integrated with the rotor-side second intermediate duct 21 b. By configuring in this manner, the same effects as those of the second embodiment can be obtained.

[0059] Next, a sixth embodiment will be described with reference to Fig. 8. Fig. 8 is a diagram showing a schematic configuration of a vehicle equipped with a rotating electric machine according to the sixth embodiment of the present invention. The same components as those in the first to fifth embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. In the sixth embodiment, an example of a vehicle will be described, in which a dump truck equipped with the rotating electric machine described in the first to fifth embodiments is mounted.

[0060] The rotating electric machine 100 is directly connected to the engine 200 via a coupling 50. When the engine 200 is driven, electric power is supplied from the rotating electric machine 100 to power converters 201a and 201b. The power converter 201a supplies electric power to a driving rotating electric machine 300 of the dump truck. The dump truck travels by driving the traveling wheels with the driving rotating electric machine 300. On the other hand, the power converter 201b supplies electric power to drive auxiliary equipment such as a blower 301 that circulates a refrigerant 20 for cooling the rotating electric machine 100.

[0061] According to the sixth embodiment, it is possible to provide a dump truck equipped with a rotating electric machine with improved cooling performance.

[0062] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0063] 1...frame, 2...rotor, 3...stator, 4...bearing, 5...shaft, 6...field coil end, 7...rotor core, 8...rotor core clamp, 9...stator core, 10...stator coil end, 11...stator core clamp, 12...field coil, 13...stator coil, 14...gap, 15...damper bar, 16...rotor wedge, 17...stator wedge, 18...axial duct (hole portion), 18a...radially outer end portion, 19...back duct, 20...refrigerant, 21a...rotor side first intermediate duct, 21a1...rotor side coil portion first intermediate duct duct, 21a2...rotor side magnetic pole portion first intermediate duct, 21b...rotor side second intermediate duct, 22a...rotor side field coil ventilation passage, 22b...rotor side magnetic pole portion ventilation passage, 23...stator side ventilation passage, 24...magnetic pole portion, 25...bridge portion, 26...radially inner end portion, 31...stator side intermediate duct, 50...coupling, 100...rotating electric machine, 200...engine, 201a...power converter, 201b...power converter, 210...thick portion, 211...rotor inner diameter side intermediate duct, 212...annular intermediate duct, 300...driving rotating electric machine, 301...blower

Claims

1. A rotating electric machine comprising: a rotor in which field coils are wound in slots in a rotor core; and a stator arranged radially outside the rotor with a gap provided, the stator core having a stator coil wound around it; wherein the rotor core comprises: a plurality of voids that penetrate the rotor in the axial direction to allow a refrigerant to flow, and that are formed along the circumferential direction at positions radially inside the field coil; magnetic pole portions that are located radially outside bridge portions that connect adjacent voids and are located between adjacent field coils in the circumferential direction; and a plurality of rotor-side intermediate ducts that extend from the radially inside to the radially outside of the rotor and form rotor-side ventilation passages for flowing the refrigerant through the field coil and the magnetic pole portions; the rotor-side intermediate ducts comprise: a rotor-side first intermediate duct whose radially inside tip portion is located radially outside the radially outer end portion of the void portion; and a rotor-side second intermediate duct whose radial length is longer than that of the rotor-side first intermediate duct. A rotating electric machine characterized in that the rotor-side first intermediate duct is disposed at a circumferential end of the magnetic pole portion.

2. A rotating electric machine according to claim 1, characterized in that the stator core is provided with a stator side intermediate duct that forms a stator side ventilation passage for allowing the refrigerant discharged from the rotor side ventilation passage to flow to the stator coil.

3. A rotating electric machine according to claim 2, characterized in that the rotor side intermediate duct and the stator side intermediate duct are aligned in the axial direction.

4. A rotating electric machine according to claim 2, wherein the radially inner ends of the rotor-side intermediate duct and the stator-side intermediate duct are formed in an arc shape.

5. A rotating electric machine as claimed in claim 2, characterized in that a frame for fixing the stator core is provided on the radially outer side of the stator core, and a back duct is provided between the stator core and the frame, communicating in the axial direction and connecting to the stator side ventilation passage.

6. A rotating electric machine according to claim 1, characterized in that the rotor-side second intermediate duct is arranged from the bridge portion to the magnetic pole portion.

7. A rotating electric machine according to claim 6, characterized in that a plurality of said rotor-side second intermediate ducts are provided in one area extending from said bridge portion to said magnetic pole portion.

8. A rotating electric machine according to claim 1, characterized in that the ventilation passage for circulating the refrigerant through the field coil is constituted solely by the rotor-side first intermediate duct.

9. A rotating electric machine according to claim 1, characterized in that a cylindrical damper bar is provided between adjacent slots, and the circumferential width of the rotor-side intermediate duct is smaller than the diameter of the damper bar.

10. A rotating electric machine according to claim 1, characterized in that a thickened portion having a thickened circumferential width is provided on the radially inner side of the rotor-side second intermediate duct.

11. A rotating electric machine according to claim 8, characterized in that a rotor inner diameter side intermediate duct is provided on the radially inner side of the hollow portion and on the radially inner extension of the rotor side first intermediate duct.

12. A rotating electric machine according to claim 8, characterized in that a circular rotor inner diameter side intermediate duct is provided radially inside the hollow portion, which is integrated with the rotor side second intermediate duct.

13. A vehicle comprising a rotating electric machine directly connected to an engine, a blower driven by the electric power of said rotating electric machine to circulate a refrigerant through said rotating electric machine, and a driving rotating electric machine that drives wheels for running by the electric power of said rotating electric machine, wherein said rotating electric machine is any one of claims 1 to 12.

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