Motor

Abstract

A motor (100) comprises: a motor housing (1) that has a cylindrical frame (1a); a stator (2) that is disposed in the inner periphery of the frame (1a); a rotor that is disposed in the inner periphery of the stator (2); a fan housing that is attached to one end part of the motor housing (1) in the axial direction; and a cooling fan that is disposed inside the fan housing. Formed in the frame (1a) is a space (1f) that passes through the frame (1a) in the axial direction and that is open on the radially inward side. The portion of the space (1f) that is open on the radially inward side is closed by an outer peripheral part (2e) of the stator (2). The space (1f) and the outer peripheral part (2e) of the stator (2) form a ventilation passage (11) which extends in the axial direction and which has a closed cross-section. Provided only to an inner peripheral part (1g) of the frame (1a) is a first cooling fin (1i) that extends radially inward toward the outer peripheral part (2e) of the stator (2) and that is positioned in the ventilation passage (11).

Description

Motor

[0001] The present disclosure relates to a motor with a cooling fan.

[0002] Conventionally, motors with cooling fans have been known. Generally, motors with cooling fans used in industrial applications require high output and high torque. As the output and torque of motors with cooling fans increase, the amount of heat generated from the stator coil also increases. Therefore, motors with cooling fans equipped with a structure that efficiently cools the stator have been developed.

[0003] For example, Patent Document 1 discloses a motor with a cooling fan in which a space that opens radially inward is formed in the inner peripheral part of a frame disposed around the outer periphery of a stator, and the part of the space that opens radially inward is blocked by the outer peripheral part of the stator, thereby forming a ventilation path with a closed cross section that extends in the axial direction. With the technology disclosed in Patent Document 1, the airflow generated by the cooling fan passes through the ventilation path without diffusing into the atmosphere around the motor with a cooling fan, thereby enabling efficient cooling of the stator.

[0004] Japanese Utility Model Application Laid-Open Publication No. 1-157554

[0005] However, the technology disclosed in Patent Document 1 has a structure in which the stator is held by the inner periphery of the frame, and in order to obtain a frictional force that prevents the stator from rotating relative to the frame when the motor with a cooling fan is running, it is necessary to ensure a sufficient contact area between the inner periphery of the frame and the outer periphery of the stator. On the other hand, with the technology disclosed in Patent Document 1, if the contact area between the inner periphery of the frame and the outer periphery of the stator is increased, the surface area of ​​the ventilation path must inevitably be reduced, resulting in the problem of insufficient cooling of the stator.

[0006] The present disclosure has been made in view of the above, and aims to provide a motor that can improve the cooling performance for the stator while ensuring a frictional force that prevents the stator from rotating.

[0007] In order to solve the above-mentioned problems and achieve the object, the motor according to the present disclosure includes a motor housing having a cylindrical frame, a stator arranged on the inner periphery of the frame, a rotor arranged on the inner periphery of the stator, a shaft connected to the rotor, a fan housing attached to one axial end of the motor housing, and a cooling fan arranged inside the fan housing. The frame has a space that penetrates the frame in the axial direction and opens radially inward. The portion of the space that opens radially inward is closed by the outer periphery of the stator. The space and the outer periphery of the stator form an air passage with a closed cross section that extends axially and through which airflow generated by the cooling fan passes. The frame is provided with a first cooling fin only on the inner periphery, extending radially inward toward the outer periphery of the stator and positioned within the air passage.

[0008] The motor according to the present disclosure has the advantage of being able to improve the cooling performance for the stator while ensuring the frictional force that prevents the stator from rotating.

[0009] FIG. 1 is a half-side cross-sectional view showing the configuration of a motor according to a first embodiment, taken along the axial direction of the motor; FIG. 2 is a cross-sectional view showing the configuration of a frame and a stator of a motor according to the first embodiment, taken along a direction perpendicular to the axial direction; FIG. 3 is a partially enlarged cross-sectional view showing the configuration of a frame and a stator of a motor according to a second embodiment, taken along a direction perpendicular to the axial direction; FIG. 4 is a partially enlarged cross-sectional view showing the configuration of a frame and a stator of a motor according to a first modified example of the second embodiment, taken along a direction perpendicular to the axial direction; FIG. 1 is a diagram schematically illustrating a stator according to embodiment 2 and a molding location where a second cooling fin is molded; FIG. 2 is a partially enlarged cross-sectional view showing the configuration of a motor according to embodiment 3, where the motor is cut along a direction perpendicular to the axial direction; FIG. 3 is a partially enlarged cross-sectional view showing the configuration of a motor according to a first modified example of embodiment 3, where the motor is cut along a direction perpendicular to the axial direction; FIG. 4 is a partially enlarged cross-sectional view showing the configuration of a motor according to embodiment 4, where the motor is cut along a direction perpendicular to the axial direction;

[0010] A motor according to an embodiment will be described in detail below with reference to the drawings, but the present invention is not limited to the embodiment.

[0011] First Embodiment. FIG. 1 is a half-side cross-sectional view showing the configuration of a motor 100 according to a first embodiment, taken along the axial direction of the motor 100. FIG. 2 is a cross-sectional view showing the configuration of a frame 1a and a stator 2 of the motor 100 according to the first embodiment, taken along the direction perpendicular to the axial direction of the motor 100. As shown in FIG. 1 , the motor 100 includes a motor housing 1, a stator 2, a rotor 3, a shaft 4, a fan housing 5, and a cooling fan 6. The stator core 2a (described later) of the stator 2 is formed in a cylindrical shape having a central axis C. Hereinafter, when describing the directions of each component of the motor 100, the direction parallel to the central axis C is referred to as the axial direction, the direction perpendicular to the central axis C is referred to as the radial direction, and the direction of rotation about the central axis C is referred to as the circumferential direction. In this specification, the inner periphery and outer periphery refer to the inner periphery and outer periphery of the cylindrical stator core 2a. Furthermore, the left side of FIG. 1 refers to one axial direction, and the right side of FIG. 1 refers to the other axial direction.

[0012] The motor housing 1 is a cylindrical member that houses the stator 2, the rotor 3, and part of the shaft 4. The motor housing 1 has a frame 1a, a first bracket 1b, and a second bracket 1c. The first bracket 1b and the second bracket 1c are arranged axially apart from each other with the frame 1a in between.

[0013] The frame 1a has a cylindrical shape with both axial ends open. As shown in Fig. 2, the frame 1a has a cylindrical shape with a roughly octagonal outer periphery and a circular inner periphery. As shown in Fig. 1, the frame 1a connects the first bracket 1b and the second bracket 1c.

[0014] The first bracket 1b is attached to one axial end of the frame 1a. The first bracket 1b closes a portion of the opening at one axial end of the frame 1a. The second bracket 1c is attached to the other axial end of the frame 1a. The second bracket 1c closes a portion of the opening at the other axial end of the frame 1a. Each of the first bracket 1b and the second bracket 1c has an insertion hole 1d into which the shaft 4 is inserted. A bearing 7 is disposed on a portion of the inner circumferential surface of each insertion hole 1d. The frame 1a may have a cylindrical shape with a bottom. In this configuration, the motor housing 1 has one bracket attached to one or the other axial end of the frame 1a.

[0015] The stator 2 is disposed on the inner periphery of the frame 1a. As shown in Fig. 2, the stator 2 is fitted and held in the inner periphery of the frame 1a. The stator 2 has a stator core 2a and a plurality of coils 2b.

[0016] The stator core 2a is, for example, a laminate of multiple electromagnetic steel sheets stacked in the axial direction. The electromagnetic steel sheets that make up the stator core 2a are annular in shape. The multiple electromagnetic steel sheets are fixed to each other by crimping, welding, adhesive, or the like. In this embodiment, the stator core 2a has a cylindrical shape. The stator core 2a has multiple teeth 2c arranged in the circumferential direction and a back yoke portion 2d that connects the multiple teeth 2c at the outer peripheries of each tooth 2c.

[0017] The plurality of teeth 2c are arranged radially around the central axis C. The plurality of teeth 2c are arranged at equal angles in the circumferential direction. The back yoke portion 2d is formed in a cylindrical shape.

[0018] The coil 2b is wound around each of the multiple teeth 2c. The coil 2b generates a magnetic field for rotating the rotor 3 and shaft 4 shown in FIG. 1 in the circumferential direction. A magnetic field is generated when an AC current is supplied to the coil 2b from an AC power supply (not shown). This magnetic field generates a torque that rotates the rotor 3 and shaft 4 shown in FIG. 1 in the circumferential direction, thereby rotating the rotor 3 and shaft 4 in the circumferential direction. The AC power supply is, for example, an inverter device.

[0019] As shown in FIG. 1 , the rotor 3 is disposed on the inner periphery of the stator 2. The rotor 3 is disposed with a gap between it and the stator 2. The rotor 3 is rotatable about a central axis C as a rotation axis. In this embodiment, the rotor 3 has a cylindrical shape. The rotor 3 is, for example, a laminate of multiple electromagnetic steel plates stacked in the axial direction. The electromagnetic steel plates that make up the rotor 3 have an annular shape. Each of the multiple electromagnetic steel plates is fixed to one another by caulking, welding, adhesive bonding, or the like. A through hole 3 a extending in the axial direction is formed in the center of the rotor 3.

[0020] The shaft 4 is connected to the rotor 3. The shaft 4 is disposed in the through hole 3a of the rotor 3 and extends in the axial direction. The shaft 4 is disposed coaxially with the central axis C. The shaft 4 is rotatably supported by two bearings 7. One axial end of the shaft 4 protrudes into the accommodation recess 1e (described below) through the insertion hole 1d of the first bracket 1b. The other axial end of the shaft 4 protrudes outside the motor housing 1 through the insertion hole 1d of the second bracket 1c.

[0021] An accommodating recess 1e is formed at one axial end of the first bracket 1b, recessed in the other axial direction toward the frame 1a. The accommodating recess 1e is open on one axial side. A detector 8 is disposed in the accommodating recess 1e. The detector 8 is a device for detecting the circumferential angle of the shaft 4. The detector 8 has a scale 8a having multiple magnetic poles or scribed lines and a sensor 8b that detects the rotation angle of the shaft 4 from the scale 8a. The scale 8a is attached to a portion of the shaft 4 that protrudes from the insertion hole 1d of the first bracket 1b. The sensor 8b is attached to the bottom surface of the accommodating recess 1e. The opening of the accommodating recess 1e is closed by a detector cover 9. The detector cover 9 covers the detector 8 from one axial side.

[0022] The fan housing 5 is attached to one axial end of the motor housing 1. More specifically, the fan housing 5 is attached to one axial end of the first bracket 1b. The fan housing 5 is box-shaped with an open surface facing the motor housing 1. The fan housing 5 has a peripheral wall 5a and an axial end wall 5b. The peripheral wall 5a is a cylindrical portion extending in the circumferential direction. One axial end of the peripheral wall 5a is closed by the axial end wall 5b. The axial end wall 5b has a plurality of exhaust ports 11e formed therein for discharging airflow that has flowed into the ventilation passage 11, which will be described later. The other axial end of the peripheral wall 5a is open.

[0023] The cooling fan 6 is disposed inside the fan housing 5. The cooling fan 6 generates an airflow that passes through the ventilation passage 11. The white arrow Y in Fig. 1 indicates the flow of the airflow. Hereinafter, the direction in which the airflow flows will be referred to as the "flow direction." The airflow flows from one side to the other in the axial direction.

[0024] Next, the configuration of the ventilation passage 11 and the configuration around the ventilation passage 11 will be described in detail.

[0025] As shown in FIG. 2 , the frame 1a has a space 1f that penetrates the frame 1a in the axial direction and opens radially inward. The radially inward opening of the space 1f is blocked by the outer periphery 2e of the stator 2. The space 1f and the outer periphery 2e of the stator 2 form a first ventilation passage 11a. In this embodiment, the first ventilation passages 11a are located at the four corners of the frame 1a, but this may be changed as appropriate. The number of first ventilation passages 11a is four in this embodiment, but this may be changed as appropriate. Changing the position and number of the first ventilation passages 11a also changes the position and number of the space 1f as appropriate. As shown in FIG. 1 , the first ventilation passage 11a is a closed cross section that extends axially and through which the airflow generated by the cooling fan 6 passes. An inlet 11d is formed at the other axial end of the frame 1a to allow airflow from outside the motor 100 to flow into the first ventilation passage 11a.

[0026] The first bracket 1b has a second ventilation passage 11b formed therein, which communicates with the first ventilation passage 11a. The second ventilation passage 11b is connected to the downstream end (one axial end) of the first ventilation passage 11a in the airflow direction. The second ventilation passage 11b is located radially outward of the bearing 7 and the accommodating recess 1e.

[0027] A third ventilation passage 11c communicating with the second ventilation passage 11b is formed in the fan housing 5. The third ventilation passage 11c is connected to the downstream end of the second ventilation passage 11b in the airflow direction (one end in the axial direction). A bell mouth 10 whose diameter gradually decreases toward the downstream side in the airflow direction (one end in the axial direction) is provided inside the fan housing 5. The downstream end of the bell mouth 10 in the airflow direction is connected to the cooling fan 6. The bell mouth 10 is part of the wall surrounding the third ventilation passage 11c.

[0028] In this embodiment, the first ventilation passage 11a, the second ventilation passage 11b, and the third ventilation passage 11c form the ventilation passage 11. That is, the first ventilation passage 11a, the second ventilation passage 11b, and the third ventilation passage 11c are each part of the ventilation passage 11. When the cooling fan 6 is driven, an airflow is generated that flows into the ventilation passage 11 from the inlet 11d and is discharged from the outlet 11e. Specifically, the airflow passes through the inlet 11d, the first ventilation passage 11a, the second ventilation passage 11b, the third ventilation passage 11c, and the cooling fan 6 in this order, and is discharged to the outside of the motor 100 from the outlet 11e. Heat generated in the coil 2b of the stator 2 is dissipated to the outside of the motor 100 via the airflow flowing through the ventilation passage 11.

[0029] As shown in FIG. 2 , a plurality of first cooling fins 1i are provided only on the inner periphery 1g of the frame 1a. The first cooling fins 1i extend radially inward toward the outer periphery 2e of the stator 2. The first cooling fins 1i are located within the first ventilation passage 11a. The first cooling fins 1i are provided on a portion of the inner periphery 1g of the frame 1a that faces the first ventilation passage 11a. A gap is provided between the tip of the first cooling fin 1i and the outer periphery 2e of the stator 2. In other words, the tip of the first cooling fin 1i does not contact the outer periphery 2e of the stator 2. In this embodiment, the shape of the first cooling fin 1i when viewed along the axial direction is generally rectangular, but this may be modified as appropriate.

[0030] Next, the effects of the motor 100 according to this embodiment will be described.

[0031] In this embodiment, as shown in FIG. 2 , the frame 1 a has a space 1 f that penetrates the frame 1 a in the axial direction and opens radially inward. Furthermore, in this embodiment, the portion of the space 1 f that opens radially inward is blocked by the outer periphery 2 e of the stator 2. Furthermore, in this embodiment, as shown in FIG. 1 , the space 1 f and the outer periphery 2 e of the stator 2 form a first ventilation passage 11 a, which is a closed cross-section that extends axially and through which the airflow generated by the cooling fan 6 passes. Furthermore, in this embodiment, as shown in FIG. 2 , the frame 1 a has a first cooling fin 1 i only on the inner periphery 1 g, which extends radially inward toward the outer periphery 2 e of the stator 2 and is positioned within the first ventilation passage 11 a. With this configuration, the first cooling fin 1 i becomes part of the surface of the first ventilation passage 11 a, and the surface area of ​​the first cooling fin 1 i is also included in the surface area of ​​the first ventilation passage 11 a. Therefore, even when a sufficient contact area between the inner peripheral portion 1g of the frame 1a and the outer peripheral portion 2e of the stator 2 is ensured so that the stator 2 does not rotate, the surface area of ​​the first ventilation passage 11a can be increased. This promotes heat exchange between the airflow and the surface of the first ventilation passage 11a, improving the cooling performance for the stator 2. Therefore, in this embodiment, the cooling performance for the stator 2 can be improved while ensuring a frictional force that prevents the stator 2 from rotating.

[0032] Conventionally, a technique has been known in which an air passage is formed between the outer periphery of the frame and the covering member by covering the outer periphery of the frame with a covering member such as an air guide cover. In this conventional technique, the covering member is required, which increases the number of parts and the number of assembly steps, thereby increasing manufacturing costs. In this embodiment, as shown in FIG. 2 , the first air passage 11a is formed by a space 1f formed in the frame 1a and the outer periphery 2e of the stator 2, eliminating the need for a covering member such as an air guide cover. This reduces the number of parts and the number of assembly steps, thereby reducing manufacturing costs, compared to when an air passage is formed using a covering member such as an air guide cover.

[0033] The frame 1a and the first cooling fin 1i shown in FIG. 2 are preferably made of a material with high thermal conductivity, such as aluminum. This allows the frame 1a and the first cooling fin 1i to be integrally formed by extrusion or pultrusion. In this embodiment, a space 1f opening radially inward is formed in the frame 1a, and the radially inward opening of the space 1f is blocked by the outer peripheral portion 2e of the stator 2, thereby forming the first ventilation passage 11a with a closed cross-section. In other words, the frame 1a itself has an open space 1f. This reduces the pressure on the frame 1a and the mold during extrusion or pultrusion molding compared to when a closed-cross-section ventilation passage is formed in the frame 1a itself. This reduces molding defects in the frame 1a, extends the mold life, and reduces manufacturing costs.

[0034] In this embodiment, as shown in Fig. 2, a space 1f that opens radially inward is formed in the frame 1a, so that the outer circumferential portion 2e of the stator 2 fits only partially into the inner circumferential portion 1g of the frame 1a. This reduces the compressive stress generated in the stator 2 compared to when the outer circumferential portion 2e of the stator 2 fits over the entire inner circumferential portion 1g of the frame 1a, thereby suppressing iron loss in the stator 2. This reduces the amount of heat generated by the stator 2, thereby suppressing a temperature rise in the motor 100.

[0035] Next, a modification of the first embodiment will be described.

[0036] 2, in this embodiment, the tip of the first cooling fin 1i is not in contact with the outer periphery 2e of the stator 2, but the tip of the first cooling fin 1i may be in contact with the outer periphery 2e of the stator 2. In this way, heat exchange between the first cooling fin 1i and the stator 2 is promoted, and the cooling performance for the stator 2 can be further improved.

[0037] As shown in Figure 2, as long as a first ventilation passage 11a with a closed cross section extending in the axial direction is formed by a space 1f in an inner peripheral portion 1g of the frame 1a and an outer peripheral portion 2e of the stator 2, the structure of each component of the motor 100 is not limited to the illustrated example. For example, the shapes of the stator 2, frame 1a, first ventilation passage 11a, and first cooling fins 1i are not limited to the illustrated example and may be changed as appropriate. Furthermore, for example, the number and positions of the first ventilation passages 11a and first cooling fins 1i are not limited to the illustrated example and may be changed as appropriate.

[0038] Second Embodiment Next, a motor 100A according to a second embodiment will be described with reference to FIG. 3. FIG. 3 is a partially enlarged cross-sectional view showing the configuration of the frame 1a and stator 2 of the motor 100A according to the second embodiment, taken along a direction perpendicular to the axial direction of the motor 100A. This embodiment differs from the first embodiment in that the motor 100A includes second cooling fins 2f. In the second embodiment, parts that overlap with those in the first embodiment are designated by the same reference numerals and will not be described again.

[0039] A plurality of second cooling fins 2f are provided on the outer periphery 2e of the stator 2. The second cooling fins 2f extend radially outward toward the inner periphery 1g of the frame 1a. The second cooling fins 2f are located within the first ventilation passage 11a. The second cooling fins 2f are provided on a portion of the outer periphery 2e of the stator 2 facing the first ventilation passage 11a. The first cooling fins 1i and the second cooling fins 2f are aligned in the circumferential direction, but may be offset in the circumferential direction. A gap is provided between the tip of the first cooling fin 1i and the tip of the second cooling fin 2f. In other words, the tip of the first cooling fin 1i and the tip of the second cooling fin 2f do not contact each other. In this embodiment, the shape of the second cooling fin 2f when viewed along the axial direction is rectangular, but this shape may be modified as appropriate.

[0040] The second cooling fins 2f are provided on each of the multiple electromagnetic steel plates that make up the stator core 2a. In the illustrated example, the second cooling fins 2f provided on each of the multiple electromagnetic steel plates are positioned to coincide in the circumferential direction. That is, the second cooling fins 2f provided on each of the multiple electromagnetic steel plates are positioned to overlap when viewed along the axial direction, and the second cooling fins 2f at the back of the page in Figure 3 are not visible. When an annular electromagnetic steel plate is punched out from a rectangular electromagnetic steel plate using a press, the annular electromagnetic steel plate and the second cooling fins 2f can be formed integrally.

[0041] In this embodiment, second cooling fins 2f are provided on the outer periphery 2e of the stator 2, extending radially outward toward the inner periphery 1g of the frame 1a and positioned within the first ventilation passage 11a. With this configuration, the second cooling fins 2f become part of the surface of the first ventilation passage 11a, and the surface area of ​​the second cooling fins 2f is also included in the surface area of ​​the first ventilation passage 11a, thereby increasing the surface area of ​​the first ventilation passage 11a. This further promotes heat exchange between the airflow and the surface of the first ventilation passage 11a, thereby further improving the cooling performance for the stator 2.

[0042] Next, a modification of the second embodiment will be described.

[0043] In this embodiment, the tips of the first cooling fins 1i and the second cooling fins 2f do not contact each other, but the tips of the first cooling fins 1i and the second cooling fins 2f may contact each other. Furthermore, the tips of the first cooling fins 1i do not contact any part of the outer circumferential portion 2e of the stator 2 other than the second cooling fins 2f, but they may contact any part of the outer circumferential portion 2e of the stator 2 other than the second cooling fins 2f. Furthermore, in this embodiment, the tips of the second cooling fins 2f do not contact any part of the inner circumferential portion 1g of the frame 1a other than the first cooling fins 1i, but they may contact any part of the inner circumferential portion 1g of the frame 1a other than the first cooling fins 1i. These configurations further promote heat exchange between the frame 1a and the stator 2, thereby further improving the cooling performance for the stator 2.

[0044] The second cooling fins 2f may also have the configuration shown in Figure 4. Figure 4 is a partially enlarged cross-sectional view showing the configuration of the frame 1a and the stator 2 of a motor 100B according to a first modified example of the second embodiment, taken along a direction perpendicular to the axial direction of the motor 100B. Fastening holes 2g for inserting bolts 12 are formed in some of the multiple second cooling fins 2f. The fastening holes 2g penetrate the second cooling fins 2f in the axial direction. The fastening holes 2g have a circular shape. In this modified example, the shape of the second cooling fins 2f with the fastening holes 2g formed therein is approximately semicircular, but may be modified as appropriate.

[0045] A second cooling fin 2f with a fastening hole 2g formed therein is provided on each of the multiple electromagnetic steel plates constituting the stator core 2a. The second cooling fins 2f provided on each of the multiple electromagnetic steel plates are positioned to overlap when viewed axially, and in FIG. 4, the second cooling fins 2f at the back of the page are not visible. The multiple electromagnetic steel plates constituting the stator core 2a can be fixed to each other by passing a bolt 12 through the fastening hole 2g of each of the multiple electromagnetic steel plates. When an annular electromagnetic steel plate is punched out from a rectangular electromagnetic steel plate using a press, the annular electromagnetic steel plate, the second cooling fin 2f, and the fastening hole 2g can be formed integrally. Note that fastening holes 2g may be formed in all of the multiple second cooling fins 2f.

[0046] In this modification, the second cooling fins 2f are formed with fastening holes 2g for receiving bolts 12. Furthermore, in this modification, the second cooling fins 2f with fastening holes 2g formed therein are provided on each of the plurality of electromagnetic steel plates constituting the stator core 2a. Furthermore, in this modification, each of the plurality of electromagnetic steel plates constituting the stator core 2a is fastened to one another with bolts 12 passed through the fastening holes 2g. These configurations can improve the axial rigidity of the stator 2. Note that the plurality of electromagnetic steel plates may be fastened by other means without passing the bolts 12 through the fastening holes 2g. In this way, the fastening holes 2g can be used as part of the ventilation passages 11, thereby increasing the surface area of ​​the ventilation passages 11. This further promotes heat exchange between the air flow and the surface of the ventilation passages 11, thereby further improving the cooling performance of the stator 2.

[0047] The second cooling fins 2f may also have the configuration shown in FIG. 5 . FIG. 5 is a partially enlarged cross-sectional view showing the configuration of the frame 1a and the stator 2 of a motor 100C according to a second modification of the second embodiment, taken along a cross-sectional view of the motor 100C cut in a direction perpendicular to the axial direction. In FIG. 5 , the second cooling fins 2f at the rear of the page are indicated by dashed lines. The second cooling fins 2f provided on some of the electromagnetic steel sheets and the second cooling fins 2f provided on the remaining portions of the electromagnetic steel sheets are not positioned to overlap when viewed along the axial direction, and the second cooling fins 2f at the rear of the page are visible in FIG. 5 . Hereinafter, the second cooling fins 2f provided on some of the electromagnetic steel sheets may be referred to as the front second cooling fins 2f, and the second cooling fins 2f provided on the remaining portions of the electromagnetic steel sheets may be referred to as the rear second cooling fins 2f.

[0048] The front-side second cooling fins 2f and the rear-side second cooling fins 2f are circumferentially offset from each other. The front-side second cooling fins 2f and the rear-side second cooling fins 2f are arranged in a staggered pattern. The stator 2 shown in FIG. 5 can be fabricated by stacking multiple electromagnetic steel sheets with the phases shifted by a certain angle. In this modification, the surface area of ​​the first ventilation passage 11a can be increased compared to when the second cooling fins 2f provided on each of the multiple electromagnetic steel sheets are positioned to overlap when viewed axially. This further promotes heat exchange between the airflow and the surface of the first ventilation passage 11a, thereby further improving the cooling performance of the stator 2.

[0049] Here, we will explain the forming area 13 in the electromagnetic steel sheet where the second cooling fins 2f shown in Figures 3 to 5 are formed. Figure 6 is a schematic diagram showing the stator 2 according to the second embodiment and the forming area 13 where the second cooling fins 2f are formed. Figure 6 is a diagram showing the stator 2 and the forming area 13 where the second cooling fins 2f are formed, viewed along the axial direction. Note that, for ease of explanation, the diagonal hatching of the stator 2 is omitted in Figure 6. The dot-hatched area in Figure 6 is the forming area 13 where the second cooling fins 2f shown in Figures 3 to 5 are formed, and is also a portion that becomes waste material when an annular electromagnetic steel sheet is punched out from a rectangular electromagnetic steel sheet by press. The outer circumferential portion 2e of the stator 2 is circular.

[0050] The second cooling fins 2f are provided only at the four corners of an imaginary square 14 that circumscribes the outer periphery 2e of the stator 2. The imaginary square 14 matches the outer shape of the electromagnetic steel sheet before it is pressed into an annular shape. In the illustrated example, the second cooling fins 2f are fabricated using scrap material that is left over when the annular electromagnetic steel sheet is pressed into an annular shape from the rectangular electromagnetic steel sheet. This reduces material costs while increasing the surface area of ​​the first ventilation passages 11a shown in Figures 3 to 5, thereby further improving the cooling performance for the stator 2.

[0051] As shown in Figures 3 to 5, as long as the first ventilation passage 11a with a closed cross section extending axially is formed between the space 1f in the inner peripheral portion 1g of the frame 1a and the outer peripheral portion 2e of the stator 2, the structure of each component of the motors 100A, 100B, and 100C is not limited to the illustrated example. For example, the shapes of the stator 2, frame 1a, first ventilation passage 11a, first cooling fins 1i, second cooling fins 2f, and fastening holes 2g are not limited to the illustrated example and may be changed as appropriate. Furthermore, the number and positions of the first ventilation passage 11a, first cooling fins 1i, second cooling fins 2f, and fastening holes 2g are not limited to the illustrated example and may be changed as appropriate.

[0052] Third Embodiment Next, a motor 100D according to a third embodiment will be described with reference to FIG. 7. FIG. 7 is a partially enlarged cross-sectional view showing the configuration of the motor 100D according to the third embodiment, taken along a direction perpendicular to the axial direction of the motor 100D. This embodiment differs from the first and second embodiments in that the motor 100D includes a protrusion 15. In the third embodiment, parts that overlap with those in the first and second embodiments are designated by the same reference numerals, and description thereof will be omitted.

[0053] The second cooling fin 2 f is provided with a protrusion 15 that protrudes in the circumferential direction. In this embodiment, the protrusion 15 protrudes from the tip of the second cooling fin 2 f toward one side in the circumferential direction. When viewed along the axial direction of the second cooling fin 2 f, the shape of the second cooling fin 2 f is L-shaped.

[0054] In this embodiment, the second cooling fins 2f are provided with protrusions 15 that protrude in the circumferential direction. With this configuration, the protrusions 15 become part of the surface of the first ventilation passages 11a, and the surface area of ​​the protrusions 15 is also included in the surface area of ​​the first ventilation passages 11a, thereby increasing the surface area of ​​the first ventilation passages 11a. This further promotes heat exchange between the airflow and the surface of the first ventilation passages 11a, thereby further improving the cooling performance for the stator 2.

[0055] Next, a modification of the third embodiment will be described.

[0056] In this embodiment, the tips of the first cooling fins 1i and the second cooling fins 2f do not contact each other, but the tips of the first cooling fins 1i and the second cooling fins 2f may contact each other. Furthermore, the tips of the first cooling fins 1i do not contact any part of the outer circumferential portion 2e of the stator 2 other than the second cooling fins 2f, but they may contact any part of the outer circumferential portion 2e of the stator 2 other than the second cooling fins 2f. Furthermore, in this embodiment, the tips of the second cooling fins 2f do not contact any part of the inner circumferential portion 1g of the frame 1a other than the first cooling fins 1i, but they may contact any part of the inner circumferential portion 1g of the frame 1a other than the first cooling fins 1i. These configurations further promote heat exchange between the frame 1a and the stator 2, thereby further improving the cooling performance for the stator 2.

[0057] The protrusions 15 may also have the configuration shown in FIG. 8 . FIG. 8 is a partially enlarged cross-sectional view showing the configuration of a motor 100E according to a first modification of the third embodiment, taken along a direction perpendicular to the axial direction of the motor 100E. Both the first cooling fin 1i and the second cooling fin 2f are provided with protrusions 15 that protrude in the circumferential direction. In this modification, the protrusions 15 of the first cooling fin 1i protrude from the tip of the first cooling fin 1i toward both ends in the circumferential direction. The first cooling fin 1i has a T-shape when viewed along the axial direction. The second cooling fin 2f has a protrusion 15 that protrudes from the tip of the second cooling fin 2f toward both ends in the circumferential direction. The second cooling fin 2f also has a T-shape when viewed along the axial direction. This modification can also achieve the same effects as those of the second embodiment.

[0058] The protrusions 15 may also be configured as shown in FIG. 9 . FIG. 9 is a partially enlarged cross-sectional view showing the configuration of a motor 100F according to a second modification of the third embodiment, taken along a direction perpendicular to the axial direction of the motor 100F. Both the first cooling fin 1i and the second cooling fin 2f are provided with protrusions 15 that protrude in the circumferential direction. The configuration of the protrusions 15 of the first cooling fin 1i is the same as that of the first modification. In this modification, the protrusions 15 of the second cooling fin 2f protrude in one direction and the other direction in the circumferential direction from the tip and the midpoint of the extension of the second cooling fin 2f. This modification can also achieve the same effects as those of the second embodiment.

[0059] As shown in Figures 7 to 9, the structure of each component of the motors 100D, 100E, and 100F is not limited to the illustrated example, as long as the first ventilation passage 11a with a closed cross section extending axially is formed between the space 1f in the inner peripheral portion 1g of the frame 1a and the outer peripheral portion 2e of the stator 2. For example, the first cooling fin 1i and / or the second cooling fin 2f may have a protrusion 15 protruding in the circumferential direction. Furthermore, for example, the shapes of the stator 2, frame 1a, first ventilation passage 11a, first cooling fin 1i, second cooling fin 2f, and protrusion 15 may be modified as appropriate without being limited to the illustrated example. Furthermore, for example, the number and positions of the first ventilation passage 11a, first cooling fin 1i, second cooling fin 2f, and protrusion 15 may be modified as appropriate without being limited to the illustrated example.

[0060] Fourth Embodiment Next, a motor 100G according to a fourth embodiment will be described with reference to FIG. 10. FIG. 10 is a partially enlarged cross-sectional view showing the configuration of a motor 100G according to the fourth embodiment, taken along a direction perpendicular to the axial direction of the motor 100G. This embodiment differs from the first and second embodiments in that the motor 100G includes a groove 16. In the fourth embodiment, parts that overlap with those in the first and second embodiments are designated by the same reference numerals, and description thereof will be omitted.

[0061] Axially extending grooves 16 are formed in both the portion of the inner circumferential portion 1g of the frame 1a facing the first ventilation passage 11a and the portion of the outer circumferential portion 2e of the stator 2 facing the first ventilation passage 11a. Hereinafter, when distinguishing between the grooves 16 in the inner circumferential portion 1g of the frame 1a and the grooves 16 in the outer circumferential portion 2e of the stator 2, the former will be referred to as the first groove 16a and the latter will be referred to as the second groove 16b. The first groove 16a is formed in the inner circumferential portion 1g of the frame 1a in the first cooling fin 1i and in a portion other than the first cooling fin 1i. In this embodiment, the number of first grooves 16a is plural, but may be singular. Furthermore, the second groove 16b is formed in the outer circumferential portion 2e of the stator 2 in the second cooling fin 2f and in a portion other than the second cooling fin 2f. In this embodiment, the number of second grooves 16b is plural, but may be singular. When the frame 1a is produced by extrusion or pultrusion, the frame 1a and the first groove 16a can be formed integrally. On the other hand, when an annular electromagnetic steel sheet is stamped out from a rectangular electromagnetic steel sheet by a press, the annular electromagnetic steel sheet that constitutes the stator 2 and the second groove 16b can be formed integrally.

[0062] In this embodiment, grooves 16 extending in the axial direction are formed in both the portion of the inner periphery 1g of the frame 1a facing the first ventilation passage 11a and the portion of the outer periphery 2e of the stator 2 facing the first ventilation passage 11a. With this configuration, the groove walls of the grooves 16 become part of the surface of the first ventilation passage 11a, and the surface area of ​​the groove walls of the grooves 16 is also included in the surface area of ​​the first ventilation passage 11a, thereby increasing the surface area of ​​the first ventilation passage 11a. This further promotes heat exchange between the airflow and the surface of the first ventilation passage 11a, thereby further improving the cooling performance for the stator 2.

[0063] Next, a modification of the fourth embodiment will be described.

[0064] In this embodiment, the tips of the first cooling fins 1i and the second cooling fins 2f do not contact each other, but the tips of the first cooling fins 1i and the second cooling fins 2f may contact each other. Furthermore, the tips of the first cooling fins 1i do not contact any part of the outer circumferential portion 2e of the stator 2 other than the second cooling fins 2f, but they may contact any part of the outer circumferential portion 2e of the stator 2 other than the second cooling fins 2f. Furthermore, in this embodiment, the tips of the second cooling fins 2f do not contact any part of the inner circumferential portion 1g of the frame 1a other than the first cooling fins 1i, but they may contact any part of the inner circumferential portion 1g of the frame 1a other than the first cooling fins 1i. These configurations further promote heat exchange between the frame 1a and the stator 2, thereby further improving the cooling performance for the stator 2.

[0065] As shown in FIG. 10 , the structure of each component of the motor 100G is not limited to the illustrated example, as long as a first ventilation passage 11a with a closed cross section extending in the axial direction is formed between the space 1f of the inner periphery 1g of the frame 1a and the outer periphery 2e of the stator 2. For example, a groove 16 extending in the axial direction may be formed in either or both of the portion of the inner periphery 1g of the frame 1a facing the first ventilation passage 11a and the portion of the outer periphery 2e of the stator 2 facing the first ventilation passage 11a. Furthermore, for example, the shapes of the stator 2, frame 1a, first ventilation passage 11a, first cooling fin 1i, second cooling fin 2f, and groove 16 are not limited to the illustrated example and may be modified as appropriate. Furthermore, for example, the number and positions of the first ventilation passage 11a, first cooling fin 1i, second cooling fin 2f, and groove 16 are not limited to the illustrated example and may be modified as appropriate.

[0066] Fifth Embodiment Next, a motor 100H according to a fifth embodiment will be described with reference to FIG. 11. FIG. 11 is a partially enlarged cross-sectional view showing the configuration of the motor 100H according to the fifth embodiment, taken along a direction perpendicular to the axial direction of the motor 100H. This embodiment differs from the first embodiment in that the motor 100H includes a fixing member 17. In the fifth embodiment, parts that overlap with those in the first embodiment will be designated by the same reference numerals and will not be described again.

[0067] A first fixing hole 1j is formed in the frame 1a. The first fixing hole 1j is formed at a position that avoids the first ventilation passage 11a and penetrates from the outer peripheral portion 1h to the inner peripheral portion 1g of the frame 1a. A second fixing hole 2h is formed in the stator 2. The second fixing hole 2h is formed at a position that avoids the first ventilation passage 11a and that communicates with the first fixing hole 1j. The second fixing hole 2h is located radially inward of the first fixing hole 1j. The second fixing hole 2h opens to the outer peripheral portion 2e of the stator 2. The radially inner opening of the first fixing hole 1j and the radially outer opening of the second fixing hole 2h communicate with each other. Fixing members 17 that fix the frame 1a and the stator 2 are arranged in the first fixing hole 1j and the second fixing hole 2h. The fixing members 17 are, for example, pins.

[0068] In this embodiment, a first fixing hole 1j is formed in the frame 1a at a position that avoids the first ventilation passage 11a, penetrating from the outer circumferential portion 1h to the inner circumferential portion 1g of the frame 1a. Also, in this embodiment, a second fixing hole 2h is formed in the stator 2 at a position that avoids the first ventilation passage 11a and that communicates with the first fixing hole 1j. Also, in this embodiment, fixing members 17 that fix the frame 1a and the stator 2 are arranged in the first fixing hole 1j and the second fixing hole 2h. With this configuration, the fixing members 17 arranged in the first fixing hole 1j and the second fixing hole 2h can prevent the stator 2 from rotating and moving axially, thereby simultaneously preventing the stator 2 from rotating and coming loose. In addition, when a fixing member 17 is placed in the first fixing hole 1j and the second fixing hole 2h, if a gap 18 occurs in the part of the first fixing hole 1j that is radially outer than the fixing member 17 as shown in the figure, the gap 18 may be sealed using a sealing material 19.

[0069] Next, a modification of the fifth embodiment will be described.

[0070] In this embodiment, as shown in Figure 11, as long as a first ventilation passage 11a with a closed cross section extending axially is formed between the space 1f in the inner peripheral portion 1g of the frame 1a and the outer peripheral portion 2e of the stator 2, the structure of each component of the motor 100H is not limited to the illustrated example. For example, the shapes of the stator 2, frame 1a, first ventilation passage 11a, first cooling fin 1i, first fixing hole 1j, second fixing hole 2h, fixing member 17, and sealing member 19 are not limited to the illustrated example and may be changed as appropriate. Furthermore, the number and positions of the first fixing hole 1j, second fixing hole 2h, fixing member 17, and sealing member 19 are not limited to the illustrated example and may be changed as appropriate.

[0071] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0072] REFERENCE SIGNS LIST 1 motor housing, 1a frame, 1b first bracket, 1c second bracket, 1d insertion hole, 1e accommodating recess, 1f space portion, 1g inner peripheral portion, 1h, 2e outer peripheral portion, 1i first cooling fin, 1j first fixing hole, 2 stator, 2a stator core, 2b coil, 2c teeth, 2d back yoke portion, 2f second cooling fin, 2g fastening hole, 2h second fixing hole, 3 rotor, 3a through hole, 4 shaft, 5 fan housing, 5a peripheral wall portion, 5b shaft end wall, 6 cooling fan, 7 bearing, 8 detector, 8a scale, 8b sensor, 9 detector cover, 10 bell mouth, 11 ventilation path, 11a first ventilation path, 11b second ventilation path, 11c third ventilation path, 11d inlet, 11e Exhaust port, 12 bolt, 13 molding portion, 14 imaginary square, 15 protrusion, 16 groove, 16a first groove, 16b second groove, 17 fixing member, 18 gap, 19 sealing material, 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H motor, C central shaft.

Claims

1. A motor comprising: a motor housing having a cylindrical frame; a stator arranged on an inner periphery of the frame; a rotor arranged on an inner periphery of the stator; a shaft connected to the rotor; a fan housing attached to one axial end of the motor housing; and a cooling fan arranged inside the fan housing, wherein the frame has a space formed therein that penetrates the frame in the axial direction and opens radially inward, a portion of the space that opens radially inward is blocked by the outer periphery of the stator, the space and the outer periphery of the stator form a ventilation passage with a closed cross section extending in the axial direction through which an airflow generated by the cooling fan passes, and a first cooling fin is provided only on the inner periphery of the frame, extending radially inward toward the outer periphery of the stator and positioned within the ventilation passage.

2. The motor according to claim 1, characterized in that a second cooling fin is provided on the outer periphery of the stator, extending radially outward toward the inner periphery of the frame and positioned within the ventilation passage.

3. The motor described in claim 2, characterized in that the outer periphery of the stator is circular in shape, and the second cooling fins are provided only at the four corners of an imaginary square that circumscribes the outer periphery of the stator.

4. The motor according to claim 2 or 3, characterized in that at least one of said first cooling fin and said second cooling fin is provided with a protruding portion that protrudes in the circumferential direction.

5. A motor as described in any one of claims 1 to 4, characterized in that a groove extending in the axial direction is formed in at least one of the portion of the inner periphery of the frame facing the ventilation passage and the portion of the outer periphery of the stator facing the ventilation passage.

6. A motor as described in any one of claims 1 to 5, characterized in that the frame is formed with a first fixing hole penetrating from the outer periphery to the inner periphery of the frame at a position avoiding the ventilation passage, the stator is formed with a second fixing hole at a position avoiding the ventilation passage and communicating with the first fixing hole, and fixing members for fixing the frame and the stator are arranged in the first fixing hole and the second fixing hole.

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