Traction motor for rolling stock

Abstract

To provide a vehicular main motor which can inhibit increase of the amplitude of wind noise to reduce noise by arranging multiple vanes of a cooling fan (sound sources) at positions of node parts of an acoustic mode.SOLUTION: A vehicular main motor is provided with node setting means 26 which arranges multiple vanes 13 of a cooling fan 6 at node parts of an acoustic mode when an air flow passage, which extends from a suction port 22 through an entry side space 23, a space 27 in which the multiple vanes are disposed, and an exit side passage 28 to an exhaust port 28a and in which cooling air flows, is assumed to be a straight pipe with both ends being open.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a traction motor for a railway vehicle. [Background technology]

[0002] In railway vehicles, traction motors that drive the wheels are attached to bogies located under the floor of the car body.

[0003] For example, the main electric motor for a vehicle described in Patent Document 1 comprises a stator, a rotor fixed coaxially to the rotating shaft on the inner periphery of the stator, a cylindrical frame that contains the stator and rotor, a bracket that is positioned to close one end opening of the frame and supports the rotating shaft, and a cooling fan that is fixed coaxially to the rotating shaft at a position closer to the bracket than the rotor.

[0004] The frame has a plurality of outlet flow passages formed in the circumferential direction on its outer periphery, each of which communicates from one end to the other. The cooling fan includes a main plate that separates the space between the stator and rotor from the space on the bracket side, a plurality of blades formed on the surface of the main plate facing the bracket and extending radially at intervals in the circumferential direction, and a band-ring-shaped guide that is arranged parallel to the main plate and secures the plurality of blades between them.

[0005] The bracket has a plurality of air intake ports formed at predetermined intervals in the circumferential direction, and these air intake ports are located within the area formed by the projection onto the bracket of the guide of the cooling fan arranged in the inlet flow path inside the bracket.

[0006] When the rotor and the multiple blades of the cooling fan rotate with the rotation of the rotating shaft, the cooling air that flows into the inlet flow path from the intake port of the bracket passes between the multiple blades and flows to the outer periphery of the bracket and main plate, then passes through the outlet flow path of the frame and is discharged to the outside, thereby cooling the rotor. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2015 / 118660 Summary of the Invention [Problem to be solved by the invention]

[0008] Incidentally, if we assume that the flow path (hereinafter referred to as the air flow path) through which the cooling air flowing in from the intake port of Patent Document 1 flows, through the inlet flow path, the space in which the multiple blades of the cooling fan rotate, and to the outlet flow path is a straight pipe with open ends, the acoustic mode of this air flow path will be a mode having multiple antinodes where the amplitude is maximized and multiple nodes where the amplitude is minimized due to the sound waves being reflected inside the flow path.

[0009] When cooling air collides with the multiple blades of the cooling fan in the air flow path, wind noise is generated. If the multiple blades are located in the abdomen of the acoustic mode, the amplitude of the wind noise increases, which may cause noise.

[0010] Therefore, the present invention aims to provide a traction motor for a vehicle that can suppress an increase in the amplitude of wind noise and reduce noise by arranging multiple blades (sound sources) of the cooling fan at the node positions of the acoustic mode. [Means for solving the problem]

[0011] In order to achieve the above object, a vehicle traction motor according to one aspect of the present invention includes a cylindrical housing, a stator fixed to a peripheral wall of the housing, a rotor arranged inside the stator and fixed to a rotating shaft, a cover side wall supporting the rotating shaft and covering the stator and rotor from the outside to form an intake port, a cover peripheral wall covering the outside of the peripheral wall of the housing and forming an outlet flow passage having an exhaust port at an end, a main plate separating the cover side wall from the stator and rotor and fixed to one end of the rotating shaft, a cooling fan having a plurality of blades fixed radially to a surface of the main plate facing the cover side wall on the outer periphery side and fixed to the rotating shaft, and an inlet space formed between the cover side wall and the main plate and communicating with the intake port. A node setting means is provided for positioning the plurality of blades at nodes of an acoustic mode when an air flow passage through which cooling air flows from the intake port to the inlet space, the space in which the plurality of blades are arranged, the outlet flow passage, and the exhaust port is assumed to be a straight pipe with both ends open. [Effects of the Invention]

[0012] According to the main electric motor for a vehicle of the present invention, by arranging the multiple blades (sound source) of the cooling fan at the node positions of the acoustic mode, it is possible to suppress an increase in the amplitude of the wind noise generated when the cooling air collides with the multiple blades of the cooling fan, thereby reducing noise. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an axial cross-sectional view showing a main electric motor for a vehicle according to a first embodiment of the present invention. [Figure 2] 1A and 1B show a cooling fan that constitutes a main electric motor for a vehicle according to a first embodiment, in which FIG. 1A is a view from the axial direction, and FIG. 1B is a view taken along the line AA in FIG. 1A. [Figure 3] FIG. 2 is a perspective view showing the shape of an air guide according to the first embodiment. [Figure 4] 3 is a diagram showing a state in which cooling air flows from an intake port to an inlet-side flow path, a fan housing space, and an outlet-side flow path in the vehicle main electric motor of the first embodiment. FIG. [Figure 5]This shows the acoustic mode of the air flow path through which the cooling air flows in the first embodiment, and the positioning of the sound source at the node of the acoustic mode. [Figure 6] FIG. 5 is an axial cross-sectional view showing a main electric motor for a vehicle according to a second embodiment of the present invention. [Figure 7] This shows the acoustic mode of the air flow path through which the cooling air flows in the second embodiment, and the positioning of the sound source at the node of the acoustic mode. [Figure 8] FIG. 10 is an axial cross-sectional view showing a main electric motor for a vehicle according to a third embodiment of the present invention. [Figure 9] 10 shows an acoustic mode of an air flow path through which cooling air flows in the third embodiment, and a sound source is positioned at a node of the acoustic mode. DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, a vehicle traction motor according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, identical or similar parts are designated by identical or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, and the like may differ from the actual ones. Therefore, specific thicknesses and dimensions should be determined with reference to the following description. Furthermore, it goes without saying that the drawings may include parts with different dimensional relationships and ratios.

[0015] Furthermore, the embodiments shown below are merely examples of devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the materials, shapes, structures, arrangements, etc. of the components to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

[0016] In the following description, terms indicating directions such as "upper," "lower," "left," and "right" are used with reference to the directions in the accompanying drawings. [Main electric motor for vehicle according to the first embodiment]

[0017] A vehicle main electric motor 1 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG.

[0018] FIG. 1 is an axial cross-sectional view showing a vehicle traction motor 1 according to a first embodiment that is attached to a bogie of a railway vehicle to drive the wheels.

[0019] The vehicle main motor 1 comprises a housing 2 formed from a metal material, a stator 3 fixed to the inner surface of the housing peripheral wall 2a of the housing 2, a rotor 5 arranged inside the stator 3 and fixed coaxially to the rotating shaft 4, a cooling fan 6 arranged to close one end side of the housing 2 and fixed to one end 4a side of the rotating shaft 4, and a cover 7 that covers the cooling fan 6 and the housing peripheral wall 2a from the outside.

[0020] The housing 2 comprises a cylindrical housing peripheral wall 2a, a ring-shaped first housing side wall 2b formed around the periphery of one end opening of the housing peripheral wall 2a, and a second housing side wall 2c formed by closing the other end opening of the housing peripheral wall 2a.

[0021] A bearing member 21a is disposed at the center of the second housing side wall 2c, supporting the other end 4b of the rotating shaft 4 via a bearing 21c. A disk-shaped inner wall 2e is disposed inside the second housing side wall 2c, with a ventilation space 2d defined between it and the outer periphery of the bearing member 21b. The outer diameter portion of the inner wall 2e is in slidable contact with an opening 2f formed in the second housing side wall 2c, and the inner diameter portion of the inner wall 2e is fixed to the rotating shaft 4. Ventilation holes 2g connecting the outside to the ventilation space 2d are formed in the bearing member 21b at predetermined intervals in the circumferential direction. A plurality of vanes 2h are disposed at predetermined intervals in the circumferential direction on the ventilation space 2d side of the inner wall 2e.

[0022] The stator 3 includes a stator core 9 and a stator coil 10. The stator core 9 is formed into a cylindrical shape extending along the axial direction by laminating a plurality of annular magnetic steel plates in the axial direction. A plurality of teeth (not shown) projecting radially inward are formed at an inner periphery of the stator core 9 at intervals in the circumferential direction. A plurality of slots (not shown) are formed between the teeth, and the stator coil 10 is wound around these slots.

[0023] The rotor 5 is formed into a cylindrical shape by laminating a plurality of annular magnetic steel plates along the axial direction.

[0024] 2(a), the cooling fan 6 includes a disk-shaped main plate 11, a band-ring-shaped guide plate 12 arranged opposite the outer periphery of the main plate 11, and a plurality of blades 13 formed radially at intervals in the circumferential direction between the opposing surfaces of the main plate 11 and the guide plate 12. As shown in FIG. 2(b), the main plate 11 includes a disk portion 15 having an insertion hole 14 formed at its center, a cylindrical portion 16 extending from the outer periphery of the disk portion 15 in one axial direction, and a blade forming plate 17 extending radially outward from the end of the cylindrical portion 16 and arranged approximately parallel to the guide plate 12.

[0025] As shown in Figure 1, the cooling fan 6 is arranged with the multiple blades 13 and guide plate 12 facing the outside of the housing 2 and not facing the stator 3 and rotor 5, and is fixed coaxially to the rotating shaft 4 by fitting the rotating shaft 4 into the insertion hole 14 of the disk portion 15 and aligning the outer surface of the blade forming plate 17 with the inner surface of the first housing side wall 2b of the housing 2, thereby closing the opening of the first housing side wall 2b.

[0026] 1, the cover 7 includes a disk-shaped cover side wall 18 that covers the cooling fan 6 from the outside (left side in FIG. 1) and extends in a direction perpendicular to the axis of the rotating shaft 4, and a cylindrical cover peripheral wall 19 that extends from the outer peripheral end of the cover side wall 18 in a direction along the axis of the rotating shaft 4 (left and right direction in FIG. 1) and covers the outer peripheral surface of the housing peripheral wall 2a. A shaft insertion hole 20 through which the rotating shaft 4 is inserted is formed in the center of the cover side wall 18, and a bearing member 21b is arranged between the inside of the shaft insertion hole 20 and the rotating shaft 4.

[0027] The space in which the multiple blades 13 and guide plate 12 of the cooling fan 6 are covered by the cover side wall 18 is called the fan storage space 27, and the space provided between the outer surface of the housing peripheral wall 2a and the inner surface of the cover peripheral wall 19 and having an exhaust port 28a communicating with the outside air is called the outlet flow path 28.

[0028] 1, the cover side wall 18 is provided with a plurality of air intake ports 22 that are formed at predetermined intervals in the circumferential direction and communicate with the main plate 11 of the cooling fan 6. Further, an inlet space 23 that communicates with the fan storage space 27 is provided on the inner side of the air intake ports 22.

[0029] The inlet space 23 is a space surrounded by a cover inner wall 24 formed on the cover side wall 18, which has the same radial dimension as the outer diameter side edge 22a of the intake port 22, and an annular cover step portion 25 formed by being recessed radially inward from the outer diameter side edge 22a of the intake port 22.

[0030] An air guide 26 is disposed in the inlet space 23. As shown in Fig. 3, the air guide 26 is a metal member with an L-shaped cross section that includes a band ring portion 26a and a tubular portion 26b that extends perpendicularly from the inner diameter end of the band ring portion 26a.

[0031] As shown in FIG. 1, the air guide 26 of this embodiment has an outer peripheral end of the band ring portion 26a fixed to the cover inner peripheral wall 24 of the cover side wall 18, the band ring portion 26a extending in a direction perpendicular to the axis of the rotating shaft 4, and the tubular portion 26b extending in a direction along the axis of the rotating shaft 4.

[0032] In the cooling fan 6 of the vehicle traction motor 1, the rotational force transmitted from the rotating shaft 4 causes the plurality of blades 13 to rotate, causing cooling air to flow from the plurality of air intakes 22 into the inlet space 23. As shown in FIG. 4 , the cooling air flowing in from the air intake 22 collides with the band ring portion 26a of the air guide 26, where it is straightened and redirected toward the rotating shaft 4. Then, the cooling air collides with the cover stepped portion 25 and redirects its flow along the inner periphery of the cylindrical portion 26b of the air guide 26. Next, the cooling air collides with the disk portion 15 of the main plate 11 and redirects its flow away from the rotating shaft 4. Then, the cooling air collides with the cylindrical portion 16 of the main plate 11 and redirects its flow along the outer periphery of the cylindrical portion 26b, and then flows toward the fan housing space 27 where the plurality of blades 13 are arranged. The cooling air is then sent to the outlet flow path 28 communicating with the fan housing space 27 and released into the outside air through the exhaust port 28a. The heat of the stator core 9 of the stator 3 that is conducted to the housing peripheral wall 2a is absorbed by the cooling air passing through the outlet flow passage 28 and is released to the outside through the exhaust port 28a.

[0033] FIG. 5 shows the acoustic modes of the air flow path and the position of the blades 13, which are the sound source, when it is assumed that the flow path through which cooling air flows from the intake port 22 of this embodiment, through the inlet space 23, along the periphery of the band ring portion 26a and the cylindrical portion 26b of the air guide 26, the fan storage space 27, the outlet flow path 28, and the exhaust port 28a (hereinafter referred to as the air flow path) is a straight pipe with open ends and a flow path length of L1.

[0034] The acoustic mode of a straight pipe has antinodes (where the amplitude of the pressure wave is maximum) and nodes (where the amplitude of the pressure wave is minimum) of the sound wave (pressure wave) created by the sound wave being reflected at the open end. The fundamental resonance frequency f is approximately f = v / (2 × L), where v is the speed of sound and L is the length of the straight pipe.

[0035] The acoustic mode of the air flow path shown in Figure 5 is for the case where the length of the air flow path is L1, and shows the vibration of a sound wave (pressure wave) targeted at a frequency three times the fundamental resonance frequency f1. This acoustic mode has three antinodes where the amplitude of the pressure wave is maximum, and four nodes where the amplitude of the pressure wave is minimum.

[0036] In this embodiment, the radial dimension H1 (see FIG. 3) of band ring portion 26a of air guide 26 and the axial dimension H2 (see FIG. 3) of tubular portion 26b are set to predetermined values so that multiple blades 13 are positioned at nodes of the acoustic mode of the air flow path close to intake port 22. Air guide 26 is an example of the "node setting means" recited in the claims.

[0037] Next, the operation and effects of the vehicle main motor 1 of the first embodiment will be described.

[0038] When the vehicle main motor 1 is driven, the stator core 9, the stator coil 10, and the rotor 5 become heat generating parts.

[0039] In the cooling fan 6 of the vehicle traction motor 1, rotational force is transmitted from the rotary shaft 4 to rotate the plurality of blades 13, causing cooling air to flow from the plurality of intake ports 22 into the inlet space 23, flow around the band ring portion 26a and the tubular portion 26b of the air guide 26, pass through the fan storage space 27 and the outlet flow path 28, and be discharged from the outlet port 28a. Then, the heat of the stator core 9 of the stator 3 conducted to the housing peripheral wall 2a is absorbed by the cooling air passing through the outlet flow path 28, and is discharged to the outside from the outlet port 28a.

[0040] When the cooling air collides with the plurality of blades 13 (sound source), wind noise is generated, and this wind noise is released to the outside from the exhaust port 28a of the outlet-side flow path 28 and the intake port 22.

[0041] 5, in the acoustic mode of the air flow path of this embodiment, by setting the radial dimension H1 of band ring portion 26a of air guide 26 and the axial dimension H2 of tubular portion 26b to predetermined values, the sound source (plurality of blades 13 that generate wind noise) is positioned at a node near intake port 22. In this way, by positioning the sound source (plurality of blades 13) at a node of the acoustic mode of the air flow path, it is possible to suppress an increase in amplitude of the sound (wind noise) radiated from the sound source at a frequency three times the fundamental resonance frequency f1, and reduce the noise caused by cooling fan 6. [Second embodiment of a main electric motor for a vehicle]

[0042] Next, Figures 6 and 7 show a vehicle traction motor 30 according to a second embodiment of the present invention. Note that parts that are the same as those in the first embodiment shown in Figures 1 to 5 are given the same reference numerals and descriptions thereof will be omitted.

[0043] The main electric motor 30 for a vehicle of the second embodiment shown in FIG. 6 does not have the air guide 26 used in the main electric motor 1 for a vehicle of the first embodiment, but may have it arranged in the inlet space 23 for rectifying the flow of cooling air. A feature of the vehicle main electric motor 30 of this embodiment is that the axial length of the cover peripheral wall 19a of the cover 7 is made shorter than the axial length of the housing peripheral wall 2a of the housing 2, thereby forming an outlet side flow path 31 whose axial length is shorter than the outlet side flow path 28 of the first embodiment, and the exhaust port 31a of the outlet side flow path 31 opens at a position facing the outer periphery of the housing peripheral wall 2a.

[0044] 7 shows an acoustic mode of a frequency three times the fundamental resonance frequency in the air flow path through which cooling air flows from intake port 22 to inlet space 23, fan storage space 27, outlet flow path 31, and exhaust port 31a in the second embodiment, assuming that the air flow path is a straight pipe with open ends and a flow path length of L2, and the position of blades 13, which act as the sound source. The fundamental resonance frequency of this air flow path is f2.

[0045] In this embodiment, the axial length of the outlet flow passage 31 is formed short so that the plurality of blades 13 are positioned at nodes of the acoustic mode of the air passage close to the intake port 22 .

[0046] Next, the operation and effects of the vehicle main motor 30 of the second embodiment will be described.

[0047] In the cooling fan 6 of the vehicle main motor 30 of this embodiment, rotational force is transmitted from the rotating shaft 4, causing the multiple blades 13 to rotate, causing cooling air that has flowed into the inlet space 23 from the multiple air intakes 22 to pass through the fan storage space 27 and the outlet flow path 31 and be released from the exhaust port 31a, and the heat of the stator core 9 of the stator 3 that has been conducted to the housing peripheral wall 2a is absorbed by the cooling air passing through the outlet flow path 31 and is released to the outside from the exhaust port 31a.

[0048] When the cooling air collides with the plurality of blades 13 (sound source), wind noise is generated, and this wind noise is released to the outside from the exhaust port 31a of the outlet side flow path 31. However, as shown in Fig. 7, the acoustic mode of the air flow path in this embodiment positions the sound source (the plurality of blades 13 that generate wind noise) at a node near the intake port 22 by shortening the axial length of the outlet side flow path 31. In this way, by positioning the sound source (the plurality of blades 13) at a node of the acoustic mode of the air flow path, it is possible to suppress an increase in amplitude for the frequency three times the fundamental resonance frequency f2 of the sound (wind noise) radiated from the sound source, and reduce the noise caused by the cooling fan 6.

[0049] Meanwhile, when the inner wall 2e and the plurality of blades 2h rotate together with the rotating shaft 4, cooling air flowing in from the ventilation holes 2g provided in the bearing member 21a passes through the ventilation space 2d and is discharged to the outside from the outer diameter side of the inner wall 2e. Therefore, the heat generated by the bearing 21c supporting the other end 4b of the rotating shaft 4, the rotor 5, the stator core 9, the stator coil 10, etc. is absorbed by the cooling air passing through the ventilation space 2d and released into the outside air.

[0050] In this embodiment, the exhaust port 31a of the outlet flow path 31 is opened at a position facing the outer periphery of the housing peripheral wall 2a, so that the cooling air that is discharged from the exhaust port 31a and has absorbed heat from the stator core 9 flows along the housing peripheral wall 2a and is less likely to flow toward the center of the second housing side wall 2c. Therefore, the cooling air discharged from the exhaust port 31a (the cooling air that has absorbed heat from the stator core 9) does not flow into the ventilation space 2d provided around the bearing member 21a, so that the bearing 21c arranged on the bearing member 21a, the rotor 5, the stator core 9, the stator coil 10, etc. can be reliably cooled. [Main electric motor for vehicle according to the third embodiment]

[0051] Next, FIGS. 8 and 9 show a vehicle main motor 32 according to a third embodiment of the present invention.

[0052] The main electric motor 32 for a vehicle of the second embodiment shown in FIG. 8 does not have the air guide 26 used in the main electric motor 1 for a vehicle of the first embodiment, but may have it arranged in the inlet space 23 for rectifying the flow of cooling air.

[0053] The vehicle traction motor 32 of this embodiment is characterized in that it has a housing circumferential wall 2i that protrudes axially outward (to the right in FIG. 8) from the second housing side wall 2c, and a ring-shaped housing end wall 2j that extends from the end of the housing circumferential wall 2i perpendicular to the rotating shaft 4 and in a direction away from the rotating shaft 4. The housing end wall 2j may be inclined with respect to the rotating shaft 4 from the end of the housing circumferential wall 2i.

[0054] The cover 7 of this embodiment has a cover peripheral wall 19b that protrudes axially outward from the second housing side wall 2c and extends to a position close to the housing end wall 2j, thereby forming an outlet flow path 33 that is longer in the axial direction than the outlet flow path 28 of the first embodiment, and the cover peripheral wall 19b has an exhaust port 33a of the outlet flow path 33 that opens between the ends of the housing end wall 2j.

[0055] 9 shows an acoustic mode of a frequency three times the fundamental resonance frequency in the air flow path through which cooling air flows from intake port 22 to inlet space 23, fan storage space 27, outlet flow path 33, and exhaust port 33a in the third embodiment, assuming that the air flow path is a straight pipe with open ends and a flow path length of L3, and the position of blades 13, which act as the sound source. The fundamental resonance frequency of this air flow path is f3.

[0056] In this embodiment, the axial length of the outlet side flow passage 33 is made long so that the plurality of blades 13 are positioned at nodes of the acoustic mode of the air passage close to the intake port 22 .

[0057] Next, the operation and effects of the vehicle main motor 32 of the third embodiment will be described.

[0058] In the cooling fan 6 of the vehicle main motor 32 of this embodiment, rotational force is transmitted from the rotating shaft 4, causing the multiple blades 13 to rotate, causing cooling air that has flowed into the inlet space 23 from the multiple air intakes 22 to pass through the fan storage space 27 and the outlet flow path 33 and be released from the exhaust port 33a, and the heat of the stator core 9 of the stator 3 that has been conducted to the housing peripheral wall 2i is absorbed by the cooling air passing through the outlet flow path 33 and is released to the outside from the exhaust port 33a.

[0059] When the cooling air collides with the plurality of blades 13 (sound source), wind noise is generated, and this wind noise is released to the outside from the exhaust port 33a of the outlet-side flow path 33. However, as shown in Fig. 9, the acoustic mode of the air flow path in this embodiment is such that the axial length of the outlet-side flow path 33 is long, and the sound source (the plurality of blades 13 that generate wind noise) is positioned at a node near the intake port 22. In this way, by positioning the sound source (the plurality of blades 13) at a node of the acoustic mode of the air flow path, it is possible to suppress an increase in amplitude for the frequency three times the fundamental resonance frequency f3 of the sound (wind noise) radiated from the sound source, and to reduce the noise caused by the cooling fan 6.

[0060] Furthermore, when the inner wall 2e and the blades 2h rotate together with the rotating shaft 4, the cooling air flowing in from the ventilation holes 2g provided in the bearing member 21a passes through the ventilation space 2d and is discharged to the outside from the outer diameter side of the inner wall 2e. Therefore, the heat generated by the bearing 21c supporting the other end 4b of the rotating shaft 4, the rotor 5, the stator core 9, the stator coil 10, etc. is taken by the cooling air passing through the ventilation space 2d and released into the outside air.

[0061] Furthermore, in this embodiment, because the outlet port 33a of the outlet flow path 33 that opens at the end of the cover peripheral wall 19b is provided, the cooling air that is discharged from the outlet port 33a and absorbs heat from the stator core 9 is less likely to flow toward the center of the second housing side wall 2c. As a result, the cooling air discharged from the outlet port 31a (the cooling air that absorbs heat from the stator core 9) does not flow into the ventilation space 2d provided around the bearing member 21a, so that the bearing 21c arranged on the bearing member 21a, the rotor 5, the stator core 9, the stator coil 10, etc. can be reliably cooled.

[0062] In the first to third embodiments described above, examples have been shown in which sound having a frequency three times the fundamental resonance frequency is reduced among noises generated by cooling fan 6 arranged in the air flow path, but the present invention is not limited to this. When sound having a frequency that is an integral multiple other than three times the fundamental resonance frequency is reduced among noises generated by cooling fan 6, the radial dimension H1 of band ring portion 26a of air guide 26 and the axial dimension H2 of tubular portion 26b can be adjusted so that multiple blades 13, which serve as sound sources, are positioned at nodes of the acoustic mode of the target frequency, and the flow path length L of the air flow path can also be adjusted.

[0063] Furthermore, even at frequencies close to integer multiples of the fundamental resonance frequency, there are nodes in the air flow path where the amplitude of the pressure wave is minimal, and noise at such frequencies can be reduced by positioning multiple blades 13 at the nodes of the acoustic mode, just like sounds at frequencies that are integer multiples of the fundamental resonance frequency.

[0064] Furthermore, in the first to third embodiments described above, an example has been shown in which multiple blades 13 serving as sound sources are arranged at the nodes of the acoustic mode to reduce noise. The node here does not only mean a position that completely coincides with the node, but also includes the vicinity of the node. The vicinity of the node may be, for example, a range of -10° to +10° in a sinusoidal acoustic mode. By arranging multiple blades 13 serving as sound sources near the nodes of the acoustic mode, a noise reduction effect can be achieved. The range of the vicinity may be changed as appropriate depending on the noise reduction effect.

[0065] Furthermore, in the first to third embodiments described above, examples have been shown in which multiple blades 13, which act as sound sources, are arranged at nodes of the acoustic mode to reduce noise, but the present invention is not limited to this. Noise is generated by separation of cooling air occurring at specific locations, such as the tips or centers of the multiple blades 13. Therefore, it is possible to identify the locations of the multiple blades 13 that act as sound sources, and adjust the radial dimension H1 of the band ring portion 26a of the air guide 26 and the axial dimension H2 of the tubular portion 26b so that the identified locations are located near the nodes of the acoustic mode, and it is also possible to adjust the flow path length L of the air flow path. If the locations that act as sound sources are located near the nodes of the acoustic mode, a greater noise reduction effect can be achieved.

[0066] Furthermore, in the first embodiment, the air guide 26 is described as the "node setting means," but the present invention is not limited to this. The "node setting means" may be a member other than the air guide 26, may be another member disposed in the air flow path, or may be a component of the air flow path that can adjust the length of the air flow path. [Explanation of symbols]

[0067] 1, 30, 32 Traction motors for rolling stock 2. Housing 2a Housing peripheral wall 2b First housing side wall 2c Second housing side wall (housing side wall) 2d ventilation space 2e interior wall 2f opening 2g Vent 2h wings 2i Housing peripheral wall 2j Housing end wall 3 Stator 4 rotation axes 4a one end 4b other end 5 rotors 6 Cooling Fan 7 Cover 9 Stator core 10 stator coil 11 Main plate 12 Guide plate 13 birds 14 Inset hole 15 Disc section 16 Cylindrical part 17 Wing formation plate 18 Cover side wall 19, 19a, 19b Cover peripheral wall 20 Axis insertion hole 21a Bearing member 21b Bearing member 21c bearings 22 Air intake 22a Outer diameter edge 22b Inner diameter edge 23 Entrance space 24 Cover inner wall 25 Cover step 26 Air Guide 26a Belt ring part 26b Cylinder part 27 Fan storage space 28 Outlet channel 28a Exhaust port 29 Air flow path 31 Outlet flow path 31a Exhaust port 33 Outlet flow path 33a Exhaust port L1, L2, L3 Axial length of cooling air

Claims

1. A cylindrical housing; a stator fixed to a peripheral wall of the housing; a rotor disposed inside the stator and fixed to a rotary shaft; a cover side wall that supports the rotary shaft, covers the stator and the rotor from the outside, and forms an air intake port; a cover peripheral wall that covers the housing peripheral wall from the outside and forms an outlet flow path having an exhaust port at an end thereof; a cooling fan fixed to the rotary shaft, the cooling fan including: a main plate fixed to one end of the rotary shaft and separating the cover side wall from the stator and the rotor; and a plurality of blades fixed radially to a surface of the main plate facing the cover side wall on the outer circumferential side; an inlet space formed between the cover side wall and the main plate and communicating with the intake port, a node setting means for positioning the plurality of blades at nodes of an acoustic mode when an air flow path through which cooling air flows from the intake port to the inlet space, the space in which the plurality of blades are arranged, the outlet flow path, and the exhaust port is assumed to be a straight pipe with both ends open, the node setting means is an air guide including: a band ring portion that extends in a direction perpendicular to the rotation axis and straightens the cooling air flowing in from the intake port by collision with it; and a tubular portion that extends from an inner diameter end of the band ring portion along the rotation axis and changes the flow of the cooling air into a space in which the multiple blades are arranged, and the multiple blades are positioned at the nodes of the acoustic mode by adjusting the flow path length of the cooling air flowing around the air guide in the inlet space.

2. a housing side wall that closes the inside of the housing is fixed to the other end side of the rotary shaft, 2. A traction motor for a vehicle according to claim 1, wherein the node setting means is the housing peripheral wall and the cover peripheral wall formed to extend axially outward from the housing side wall, and the plurality of blades are positioned at the nodes of the acoustic mode by adjusting the flow path length of the outlet flow path formed by the housing peripheral wall and the cover peripheral wall to be long.

3. The housing side wall is disposed on the other end side of the rotary shaft via a bearing member, and a ventilation hole is formed in the housing side wall near the bearing member to send cooling air around the bearing member; 3. The main electric motor for a vehicle according to claim 2, wherein the exhaust port is formed at an end of the peripheral wall of the housing and the peripheral wall of the cover at a position not facing the rotary shaft.

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