Electric motor device

Abstract

An electric motor device comprises: a stator (4) that has a stator magnetic body (17) and an excitation coil (3) wound around the stator magnetic body (17); a rotor (6) that has a magnetic pole facing the stator (4) and that is rotatably supported with respect to the stator (4); and a support body (Sp) that supports the stator magnetic body (17). The stator magnetic body (17) is provided with cavities (17b) from the location where the excitation coil (3) is provided to the location where the stator magnetic body is fixed to the support body (Sp). The magnetic pole of the rotor (6) faces the stator (4) in the radial direction of a coordinate system with the rotation axis of the rotor (6) as the axial direction, and the stator magnetic body (17) is fixed to the support body (Sp) at an inner diameter-side end part thereof. The cavities (17b) are provided in the radial positions between an inner diameter-side portion of a fixing part to the excitation coil (3) and a fixing part to the support body (Sp), in the stator magnetic body (17).

Description

Electric motor device Related Applications

[0001] This application claims priority to Japanese Patent Application Nos. 2023-121477, 2023-121478, and 2023-121479, filed on July 26, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an electric motor device, and more particularly to a technique for reducing the motor temperature and achieving simplification and space saving in, for example, an electromechanical integrated motor.

[0003] The following technologies have been proposed as electric motor devices: 1. A structure of an integrated electromechanical motor in which a motor and a control device for controlling the motor are modularized (Patent Document 1). 2. A drone that levitates by rotating an impeller with an electric motor (Patent Document 2). 3. An automated guided vehicle driven by an electric motor (Patent Document 3). 4. A structure of an integrated electromechanical motor equipped with a cooling fan attached to the motor body (Patent Document 4).

[0004] Japanese Patent Application Laid-Open No. 2011-234513 Japanese Patent Application Laid-Open No. 2019-167101 Japanese Patent Application Laid-Open No. 2000-132233 Japanese Patent Application Laid-Open No. 09-084294

[0005] For example, as in the electric motor device of Patent Document 1, an excitation coil is provided on a stator, and this coil is often the main heat source. The heat from the coil is mainly dissipated to the stator poles around which the coil is wound. Generally, the stator poles are simply and firmly supported by being fitted into the housing. For this reason, the heat generated by the coil is often ultimately transferred from the support portion of the stator pole to the housing.

[0006] In this case, for example, in a mechanically and electrically integrated electric motor device in which a control device is integrated with a motor magnetic circuit, as in Patent Document 1, the temperature around the control device may rise due to heat transfer from the coil. In particular, if the temperature around the drive circuit part that forms the current path for the coil rises, the current that can be passed may be limited, which may cause a problem of reduced motor output.

[0007] Even when an integrated control device structure like that of Patent Document 1 is not adopted, in many cases a bearing that rotatably supports a rotor is assembled to a housing that supports a stator. In this case, if heat generated by the coil is transferred from the stator poles to the bearing via the housing, the temperature of the bearing may rise and the lifespan may be shortened.

[0008] To address these problems, for example, a structure that interposes a heat insulating material in the heat transfer path or a housing structure that supports the stator and the control device or bearing separately may result in a complex structure and an increase in the overall size of the motor. Generally, in motors applied to the drone described in Patent Document 2 or the automated guided vehicle described in Patent Document 3, it is often necessary to reduce the motor's mounting space in order to miniaturize the drone or ensure cargo mounting space in the automated guided vehicle, and the increase in motor size may become a problem. Furthermore, if the heat transfer path is completely blocked by the above-mentioned heat insulating material, it may be difficult to dissipate heat from the coil, resulting in problems such as reduced motor performance.

[0009] Further, as an electric motor using an air-cooling method in which the motor is cooled by outside air, an electric motor equipped with a cooling fan inside the electric motor device is known, as disclosed in Patent Document 4, for example.

[0010] SUMMARY OF THE INVENTION An object of the present invention is to provide an electric motor device that employs a heat dissipation structure and that is simple and space-saving.

[0011] The electric motor device of the present invention is an electric motor device comprising a stator having a stator magnetic body and an excitation coil wound around the stator magnetic body, a rotor having magnetic poles facing the stator and supported rotatably relative to the stator, and a support body supporting the stator magnetic body, wherein a cavity is provided in the stator magnetic body between the point where the excitation coil is provided and the point where it is fixed to the support body.

[0012] According to this configuration, a cavity is provided in the stator magnetic body between the location where the excitation coil is provided and the location where it is fixed to the support. By providing a cavity in the stator magnetic body and increasing the surface area, the amount of heat dissipated from the excitation coil until it is transferred to the support is improved, suppressing the temperature rise of the support. By adopting a heat dissipation structure with a cavity in the stator magnetic body, there is no need to divide the housing or install a heat sink, etc., and it is possible to achieve simplification and space savings compared to conventional structures that include such heat sinks, etc.

[0013] The magnetic poles of the rotor may face the stator in the radial direction of a coordinate system having the rotation axis of the rotor as the axial direction, the stator magnetic body may be fixed to the support at its inner diameter side end, and the cavity may be provided in the stator magnetic body at a radial position between the inner diameter side part of the part fixed to the excitation coil and the part fixed to the support. In such an electric motor device with a radial gap type outer rotor structure, the cavity can be easily provided by utilizing the radial position in the stator magnetic body.

[0014] The magnetic poles of the rotor may face the stator in the direction of the rotor's rotational axis, the stator magnetic body may be fixed to the support at its end in the direction of the rotational axis, and the cavity may be provided in the stator magnetic body at a position in the direction of the rotational axis between a base end portion of the part fixed to the excitation coil and a part fixed to the support. In such an axial gap type electric motor device, the cavity can be easily provided by utilizing the position in the direction of the rotational axis in the stator magnetic body.

[0015] The magnetic poles of the rotor may face the stator in the direction of the rotation axis of the rotor, the stator magnetic body may be fixed to the support at an inner diameter side end of a coordinate system whose axial direction is the rotation axis of the rotor, and the cavity may be provided in the stator magnetic body at a radial position between an inner diameter side portion of a part fixed to the excitation coil and a part fixed to the support. In such an axial gap type electric motor device, the cavity can be easily provided by utilizing the radial position in the stator magnetic body.

[0016] The stator magnetic body may be provided with a plurality of cavities, which are through holes that penetrate the stator magnetic body in the axial direction, at equal circumferential intervals, the number of the evenly spaced cavities being equal to a positive integer multiple of the number of magnetic poles of the stator, and the cavities may be provided in the stator magnetic body so that the circumferential positions of the evenly spaced cavities are located midway between the magnetic poles. When the cavities are provided under the above conditions, magnetic paths separated by the cavities merge with adjacent magnetic poles, making it easier for magnetic flux to pass, and the area where the cavities are provided can also be used as a back yoke, making it possible to reduce the back yoke and further increase the heat dissipation area.

[0017] The stator magnetic body may be configured such that at least a portion of the stator magnetic body is connected non-parallel to the radial direction by the cavities. In this case, if the cavities are arranged alternately in multiple rows, the heat transfer path from the magnetic pole side where the excitation coil, which is the heat source, is arranged to the support side becomes longer. This makes it easier to dissipate heat before it is transferred to the support, making it more difficult for the temperature of the support to rise.

[0018] The rotor may be provided with a bearing that rotatably supports the rotor, and the support may include a housing that supports the bearing together with the stator magnetic body. In this case, the amount of heat dissipated from the excitation coil until it is transferred to the housing is improved, thereby suppressing heat transfer to the bearing more than in a conventional structure that does not employ a heat dissipation structure. This makes it possible to extend the life of the bearing more than in the conventional structure.

[0019] The support may include a stator frame that supports one axial end of the stator magnetic body. In this case, the amount of heat dissipated from the excitation coil until it is transferred to the stator frame is improved. When a control device for an electric motor device is mounted on the stator frame or near the stator frame, the amount of heat dissipated until it is transferred to the stator frame is improved as described above, which can suppress a temperature rise in the control device and prevent limitations on the current that can be passed. This makes it possible to prevent undesired decreases in the output of the electric motor device.

[0020] The electric vertical take-off and landing aircraft of the present invention includes any one of the electric motor devices according to the present invention. This configuration allows for the application of a space-saving electric motor device, making it easier to secure space for arranging rotors and the like compared to conventional structures, thereby enabling the overall aircraft to be made smaller and lighter.

[0021] The automated guided vehicle of the present invention is equipped with any of the electric motor devices according to the present invention. With this configuration, it is possible to apply an electric motor device that can save space, and therefore it is possible to incorporate the electric motor device into an existing vehicle without making major structural changes. This increases the degree of freedom in the design of the automated guided vehicle.

[0022] The electric motor device of the present invention may also include a motor including the rotor having a field magnet that faces the stator and generates a magnetic force, and a control device that controls the motor, wherein at least a portion of the control device is disposed within the motor so as to overlap the field magnet or the excitation coil at an axial position. The "axial position" refers to an axial position parallel to the rotational axis of the rotor. In other words, it refers to a range or region in the length direction of the rotational axis when viewed in an axial cross section (FIG. 1).

[0023] With this configuration, at least a portion of the control device is positioned within the motor in an axial direction overlapping with the field magnet or excitation coil, which allows the entire electric motor device to be configured in a more space-saving manner than in conventional configurations where the control device is completely separated from the motor magnetic circuit via the housing.

[0024] The control device may have a drive circuit unit that controls the energization state of the coil, and at least a portion of the drive circuit unit may be located on the inner diameter side at the same axial position as the field magnet or the excitation coil. The drive circuit unit optionally changes the electrical connection state between the control device's power supply source and the coil. By locating at least a portion of this drive circuit unit on the inner diameter side at the same axial position as the field magnet or the excitation coil, it is possible to reduce the size of the electric motor device.

[0025] The excitation coil and the field magnet may have different numbers of poles so that the rotor rotates with an AC current of a predetermined number of phases, and the drive circuit unit may be divided into a number equal to the number of phases and arranged at different circumferential positions. The "predetermined number of phases" is a number determined arbitrarily by design or the like, and may be determined, for example, by determining an appropriate value through testing and / or simulation. The "circumferential position" refers to a circumferential position around the rotation axis of the rotor. If the drive circuit unit is divided into a number equal to the number of phases and arranged at different circumferential positions, it is easy to ensure space for mounting the drive circuit unit.

[0026] The motor may include a bearing that rotatably supports the rotor and a bearing housing that supports the bearing in the same stationary system as the stator, and the drive circuit unit may be fixed to the outer periphery of the bearing housing, which makes it easy to ensure installation space and wiring paths for the drive circuit unit.

[0027] The stator may have a notch at a position where the drive circuit is provided to avoid interference with the drive circuit, and the stator may abut against the outer periphery of the bearing housing at a location where the notch is not provided. In this case, the stator can be supported by the bearing housing simply and robustly, and the drive circuit can be easily disposed.

[0028] The motor may include a bearing that rotatably supports the rotor, and the control device may include a smoothing circuit that suppresses power fluctuations caused by rotating the rotor, the smoothing circuit being provided facing one axial end of the bearing. The smoothing circuit may be composed of a relatively large component, such as an electrolytic capacitor. By providing such a smoothing circuit facing one axial end of the bearing, where the axial position can be easily adjusted, space for mounting the smoothing circuit can be secured. Therefore, the entire electric motor device can be configured to save space.

[0029] The motor may include a bearing housing that supports the bearing in the same stationary system as the stator, and the smoothing circuit unit may be supported by the bearing housing. In this way, the smoothing circuit unit can be provided using the bearing housing.

[0030] A plurality of the bearings may be provided coaxially with the rotating shaft of the rotor, and the axial intermediate position of the area where the plurality of bearings are provided may be offset axially opposite the smoothing circuit unit from the axial intermediate position of the stator. In this case, space for mounting the smoothing circuit unit can be efficiently secured, and the electric motor device as a whole can be configured in a space-saving manner.

[0031] Furthermore, the electric motor device of the present invention is an electric motor device equipped with a motor including a rotor having a field magnet that faces the excitation coil and generates a magnetic force, and a bearing that is arranged radially inward relative to the stator and perpendicular to the rotational axis of the rotor, and the rotor may have a main shaft that is rotatably supported by the bearing, and blade portions that are respectively connected to the main shaft and the field magnet and that generate a cooling airflow by rotating around the rotational axis.

[0032] With this configuration, the rotor is configured by connecting the field magnet and the main shaft via the blades, so the rotor itself has a ventilation function. In this case, the stator can be cooled with a space-saving structure compared to when a fan is installed inside the rotor, making it possible to reduce the size of the electric motor device.

[0033] The field magnet may be arranged radially outward of the excitation coil and facing the excitation coil in the radial direction, and the blade portion may be located between the radially inner side of the field magnet and the radially outer side of the main shaft when viewed from the direction of the rotation axis, and the field magnet and the main shaft may be connected via the blade portion.

[0034] According to this configuration, in an outer rotor type motor in which the rotor's field magnet is arranged radially outward of the stator's excitation coil, the stator can be cooled using a space-saving structure, making it possible to reduce the size of the electric motor device.

[0035] The airflow may pass through the blades in the axial direction of the rotor.

[0036] With this configuration, the blade portion that rotates as part of the rotor functions as an axial fan, and generates an airflow that flows in the direction of the rotation axis, which is directed toward the stator inside the electric motor device, allowing the stator inside the electric motor device to be cooled efficiently and the entire electric motor device to be configured to save space.

[0037] The field magnet and the excitation coil may face each other in the direction of the rotation axis, the blade portion may be located between the field magnet and the axial end of the main shaft in the direction of the rotation axis, and the field magnet and the main shaft may be connected via the blade portion.

[0038] With this configuration, even in an axial gap type motor in which the rotor's field magnet and the stator's excitation coil face each other in the axial direction of the rotating shaft, the stator inside the electric motor can be efficiently cooled by the airflow generated by the blades due to the rotation of the rotor, and the entire electric motor device can be configured to save space.

[0039] The airflow may be discharged from the blade portion radially outward of the main shaft of the rotor.

[0040] With this configuration, the blade portion that rotates as part of the rotor functions as a centrifugal fan, and an airflow is generated that flows in the outer diameter direction of the rotor's rotating shaft, which directs the airflow from the axial center to the outer peripheral surface of the main shaft and stator inside the electric motor device, allowing the inside of the electric motor device to be cooled efficiently and the entire electric motor device to be configured to save space.

[0041] Any combination of at least two features disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims is included in the present invention.

[0042] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation purposes and should not be used to define the scope of the present invention. The scope of the present invention is defined by the appended claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same or corresponding parts.

[0023] Figure 1 is a longitudinal sectional view of an electric motor device according to a first embodiment of the present invention. It is a partial enlarged view of Figure 1. It is a front view showing the structure of the stator magnetic body and excitation coil of the electric motor device. It is a partial enlarged view showing an enlarged portion of the stator magnetic body. It is a circuit diagram schematically showing the circuit configuration of a control device for the electric motor device. It is a perspective view of the electric motor device. It is a longitudinal sectional view of an electric motor device according to a second embodiment of the present invention. It is a partial enlarged view of Figure 7. It is a front view of the stator magnetic body and excitation coil of the electric motor device as seen from one axial direction. It is a side view of the stator magnetic body and excitation coil. It is a rear view of the stator magnetic body and excitation coil as seen from the other axial direction. It is a longitudinal sectional view of an electric motor device according to a third embodiment of the present invention. It is a transverse sectional view of the electric motor device. It is a longitudinal sectional view of an electric motor device according to a fourth embodiment of the present invention. Fig. 10 is a longitudinal sectional view of an electric motor device according to a fifth embodiment of the present invention; Fig. 11 is a perspective view of an electric vertical take-off and landing aircraft equipped with an electric motor device according to any one of the embodiments; Fig. 12 is an example of a schematic plan view of an automatic guided vehicle equipped with the electric motor device; Fig. 13 is another example of a schematic plan view of an automatic guided vehicle equipped with the electric motor device.

[0043] [First embodiment: radial gap type outer rotor structure] An electric motor device according to an embodiment of the present invention will be described with reference to Figures 1 to 4. This electric motor device is mounted on, for example, a vehicle.

[0044] <Overall Configuration of Electric Motor Device> As shown in Figure 1, the electric motor device includes an outer rotor motor 1 and a control device 2 that controls the motor 1. The electric motor device is a mechanically and electrically integrated electric motor device in which the motor 1 and the control device 2 are modularized. The motor 1 includes a stator 4 having an excitation coil 3, a rotor 6 having a field magnet 5 that generates a magnetic force and faces the stator 4 across a radial gap, and that is rotatably supported by the stator 4, a bearing 7 that rotatably supports the rotor 6, and a support Sp. The magnetic poles of the rotor 6 face the stator 4 in the radial direction of a coordinate system in which the rotation axis of the rotor 6 is the axial direction, and a stator magnetic body 17 (described later) of the stator 4 is fixed to the support Sp at its inner diameter end.

[0045] <Rotor> The rotor 6 has a field magnet 5, a rotor yoke 10, a rotor frame 11, blades 30, a main shaft 12, and a rotor fixed terminal 13. The field magnet 5 generates magnetic flux that contributes to the rotational torque of the rotor 6. The rotor yoke 10 forms a magnetic circuit with relatively low magnetic path resistance on the side opposite to the torque generation surface of the field magnet 5. The rotor frame 11 is connected to the field magnet 5 and the rotor yoke 10. The main shaft 12 of the rotor 6 is rotatably supported by bearings 7.

[0046] <Field Magnet and Rotor Yoke> The field magnet 5 is, for example, a permanent magnet such as a neodymium magnet or a ferrite magnet. The field magnet 5 is, for example, a plurality of magnets magnetized so that the magnetic poles parallel to the radial direction of the rotation shaft alternately reverse. The rotor yoke 10 is formed into a cylindrical shape from an iron-based material with high magnetic permeability, such as carbon steel for mechanical construction (SC material), and the field magnet 5 is fixed to the inner surface of the rotor yoke 10 by adhesive or the like. Using an iron-based material with high magnetic permeability, such as SC material, for the rotor yoke 10 is preferable because it can increase the magnetic flux and holding force of the field magnet 5. However, without providing a rotor yoke, a housing that simply holds the field magnet may be formed from a non-magnetic material, such as resin.

[0047] <Rotor Frame> The rotor frame 11 connects the main shaft 12 with the rotor yoke 10 and the field magnet 5. The rotor frame 11 is formed, for example, by insert-molding a metal part that forms a part including a fitting portion with the main shaft 12 together with the rotor yoke 10. In this way, the strength and precision of the rotor frame 11 and the main shaft 12 can be ensured while reducing the weight of the entire electric motor device.

[0048] <Main Shaft, etc.> The main shaft 12 is rotatably supported by bearings 7. A plurality of bearings 7 (two in this example) are provided coaxially on the rotating shaft of the rotor 6, spaced at a predetermined interval. These bearings 7, 7 support a radial load, which is a load in the radial direction of the rotating shaft, and an axial load, which is a load in the axial direction. As the bearings 7 that support such radial and axial loads, rolling bearings such as deep groove ball bearings or angular contact ball bearings are used.

[0049] A flange portion 12a is provided at one axial end of the main shaft 12. The flange portion 12a is formed integrally with the main shaft 12. The term "integrally formed" means that the main shaft 12 and the flange portion 12a are formed as part or the whole of a single object from a single material by, for example, forging or machining, rather than by combining multiple elements. As shown in FIG. 2 , the flange portion 12a abuts against the outer end surface 14 of the inner ring of the bearing 7 on one axial side. A retaining ring groove 12b is formed on the outer peripheral surface of the other axial end of the main shaft 12, and a retaining ring 15 is fitted into the retaining ring groove 12b. The retaining ring 15 abuts against the outer end surface 16 of the inner ring of the bearing 7 on the other axial side. The flange portion 12a and the retaining ring 15 restrain the position of the main shaft 12 in the rotational axis direction against forces acting on the main shaft 12 in the rotational axis direction.

[0050] 1 , rotor frame 11 and main shaft 12 are fixed by rotor stationary terminal 13. In this embodiment, for example, rotor stationary terminal 13 and main shaft 12 are provided with a threaded structure that screws together, and a central portion of the inner diameter side of rotor frame 11 is screwed together so as to be sandwiched between rotor stationary terminal 13 and main shaft 12 via the threaded structure.

[0051] <Stator> The stator 4 has a stator magnetic body 17 facing the field magnet 5 radially inward, and an excitation coil 3 that generates magnetic flux that contributes to the rotational torque of the rotor 6 when current is applied. The stator magnetic body 17 and excitation coil 3 are, for example, one stator magnetic body 17 with the excitation coil 3 provided thereon. The excitation coil 3 and the field magnet 5 have different numbers of poles so that the rotor 6 rotates with AC current of a predetermined number of phases. The excitation coil 3 is made up of multiple coils wound around the stator magnetic body 17, and can be configured to generate a rotational torque, which is a desired magnetic force, when current is applied to the coil 3. Figure 1 shows an example of concentrated winding in which coils are wound individually around each magnetic pole.

[0052] It is preferable to use a metal with relatively low electrical resistance, such as copper or aluminum, as the magnet wire forming the coil 3. The multiple coils 3 are connected to each other based on any specifications determined for design convenience, such as a predetermined connection method such as delta connection or star connection, a predetermined number of series or parallel connections, a predetermined number of systems, etc.

[0053] The stator magnetic body 17 is made of a material with relatively high magnetic permeability and relatively little eddy current loss due to high-frequency magnetic flux, such as a laminated electromagnetic steel sheet or a powder magnetic core. After the excitation coil 3 is provided on the stator magnetic body 17, a more robust structure can be achieved by fixing it by varnish impregnation or insert molding, etc. However, because this may increase manufacturing costs or weight, whether or not to implement such a robust structure should be selected appropriately according to design requirements.

[0054] <Regarding the Support> The support Sp includes a housing 8 and a stator frame 9. The housing 8 mainly supports the bearing 7 and the stator magnetic body 17 of the stator 4. In other words, the housing 8 supports the bearing 7 in the same stationary system as the stator 4. As shown in FIG. 2 , the housing 8 is cylindrically formed from a material such as iron, aluminum, or resin. A step 8a that abuts against an inner end surface 18 of the outer ring of one of the axially-located bearings 7 is provided near the axial middle of the inner circumferential surface of the housing 8. A step 8b that abuts against an inner end surface 19 of the outer ring of the other axially-located bearing 7 is provided near the other axially-located outer ring of the inner circumferential surface of the housing 8. Therefore, the axial positions of the housing 8, the bearings 7, and the main shaft 12 are restricted by the step portions 8a and 8b that abut against the bearings 7, the flange portion 12a, and the retaining ring 15.

[0055] 1, the stator frame 9 is fitted and fixed to one axial end of the outer circumferential surface of the housing 8, or is provided as a resin or metal part integrally molded on the outer circumferential surface of the housing 8. The stator frame 9 has a generally cylindrical shape with a bottom and an annular recess 9a formed on the outer axial portion. If the stator frame 9 and the housing 8 are made of the same material, the stator frame 9 and the housing 8 can be formed as a single part.

[0056] <Heat Dissipation Structure> A plurality of cavities 17b are provided in the inner diameter portion of the stator magnetic body 17, within a range that does not affect the magnetic circuit, to suppress a temperature rise in the support body Sp and reduce the weight of the entire device. Specifically, a plurality of cavities 17b are provided in the stator magnetic body 17 from the location where the excitation coil 3 is provided to the location where the support body Sp is fixed to the housing 8. As shown in Fig. 3 , a plurality of cavities 17b are provided in the stator magnetic body 17 at a radial position Pw between an inner diameter portion 17c of a portion fixed to the excitation coil 3 and a portion 17d of a portion fixed to the housing 8. As shown in Fig. 2 , each of the cavities 17b is a through-hole that penetrates the stator magnetic body 17 in the axial direction.

[0057] As shown in FIG. 3 , the plurality of cavities 17b include first and second cavities 17b1 and 17b2 that are concentrically arranged. The first cavities 17b1 are arranged at a predetermined radial position, concentrically about the rotation axis direction, and at an equal circumferential interval. The second cavities 17b2 are arranged at a predetermined radial position, concentrically about the rotation axis direction, and at an equal circumferential interval, radially inward from the first cavities 17b1. As shown in FIG. 4 , the shape and number of these cavities 17b can be determined appropriately for design convenience. While FIG. 4 shows an example in which each cavities 17b is approximately triangular, the cavities can be provided in any shape, such as a round hole, an elongated hole, or an approximately rectangular hole, depending on design convenience.

[0058] As shown in Fig. 3, the number of each of the equally spaced cavity groups 17b1, 17b2 is equal to a positive integer multiple of the number of magnetic poles of the stator 4. In this example, the number of each of the equally spaced cavity groups 17b1, 17b2 at the same radial position is equal to the number of magnetic poles. As shown in Fig. 4, in particular, in the first cavity group 17b1 closest to the excitation coil 3, the cavities 17b are provided in the stator magnetic body 17 so that the circumferential position Pc of the geometric center of each cavity 17b is located midway between the magnetic poles. The stator magnetic body 17 is configured so that at least a portion of the stator magnetic body 17 is connected to the radial direction non-parallel NP by the first and second cavity groups 17b1, 17b2.

[0059] As shown in Figure 1, the cylindrical portion of the stator frame 9 has openings 9b that penetrate radially. The openings 9b connect the outside of the electric motor device with the interior of the motor, including at least the cavity 17b. Airflow entering from the outside of the electric motor device through the openings 9b passes through the interior of the motor, including the cavity 17b, increasing the amount of heat dissipation from the stator magnetic body 17. The orientation, size, shape, etc. of the openings 9b may be determined according to design considerations. For example, instead of the example shown in Figure 1, a structure in which openings are provided in the axial direction of the stator frame 9 may be used.

[0060] <Sensors> For example, a rotation sensor (not shown) may be provided to detect the rotation state of the rotor 6. As the rotation sensor, for example, a resolver capable of detecting the rotation position with relatively high resolution, a magnetic encoder, or a magnetic switch that reacts when a predetermined rotor position is reached may be used. Alternatively, sensorless control may be used in which the position of the rotor 6 is estimated by the control device 2 (described later) from the energization state of the coil 3, etc., without using a rotation sensor. For example, a temperature sensor that measures the temperature of the coil 3 may be provided.

[0061] <Control Device> The control device 2 has a control circuit unit 20, a drive circuit unit 21, and a smoothing circuit unit 22. The control circuit unit 20 performs control calculations and the like for motor control. The drive circuit unit 21 includes a current-carrying element for controlling the current-carrying state of the coil 3. The smoothing circuit unit 22 suppresses power fluctuations that accompany current flow to the coil 3, i.e., power fluctuations that occur when the rotor 6 is rotated.

[0062] The drive circuit unit 21 is configured with a drive element such as an FET. The drive circuit unit 21 is disposed on the inner diameter side of the stator magnetic body 17 and is fixed to the outer periphery of the housing 8. The drive circuit unit 21 may be, for example, a circuit board on which the drive element is mounted, or may be a circuit module in which the drive element is integrally molded.

[0063] As shown in Figure 3, the stator magnetic body 17 is provided with notches 17a to avoid interference with the drive circuit unit 21 (Figure 1). The stator magnetic body 17 abuts against the outer periphery of the housing 8 at locations where the notches 17a are not provided. The term "abutting" does not refer only to a strict contact state, but is considered to be abutting as long as the shape is such that at least a portion of the body is in contact.

[0064] For example, a shape in which there is a fitting gap of, for example, several tens of μm between the stator magnetic body 17 and the housing 8 also falls under the category of abutment, and for example, the stator magnetic body 17 and the housing 8 fitted together with a fitting gap may be fixed with an adhesive or the like that penetrates into minute gaps. The drive circuit unit 21 in Fig. 1 may be provided with a snubber circuit or the like for suppressing voltage surges, which is more effective when placed near the drive element.

[0065] The control circuit 20 is a motor control circuit excluding the drive circuit and other components, which are provided separately, and is fixed to the annular recess 9a on the axially outer side of the stator frame 9. The control circuit 20 includes at least a motor control calculation unit and a control power supply circuit. Examples of the calculation unit include a microcomputer and a field-programmable gate array (FPGA). The inner periphery of the stator frame 9 is formed with a through-hole that penetrates from the axially outer side to the inner side in the direction of the rotation axis. The control circuit 20 and the drive circuit 21 are electrically connected by, for example, a bus bar provided in the through-hole or the like of the stator frame 9.

[0066] The smoothing circuit unit 22 includes a relatively large capacitor mounted on a circuit board. The smoothing circuit unit 22 is provided so as to face one axial end (the right end in FIG. 1 ) 7 a of one axial bearing 7. In this example, the smoothing circuit unit 22 is provided at the right end in FIG. 1 coaxially with the bearing 7, but this does not necessarily have to be the case. The smoothing circuit unit 22 is supported by the bearing housing 8 so as to fit inside the bearing housing 8.

[0067] Specifically, a partition wall 25 is formed on the inner peripheral surface of the bearing housing 8, separating the space in which the bearings 7, 7 and main shaft 12 etc. are provided from the space in which the smoothing circuit unit 22 is provided. The smoothing circuit unit 22 is fixed in the space surrounded by the inner peripheral surface of the bearing housing 8, the partition wall 25, and a cover 26 (described later) by molding with a non-conductive resin such as potting. The smoothing circuit unit 22 and the control circuit unit 20 are electrically connected.

[0068] <Wiring Section, Cover, etc.> A wiring section 29 that supplies power to the control device 2 is provided in the annular recess 9a of the stator frame 9, and a cover 26 that covers the control device 2 is provided. The specifications of the wiring section 29 and the cover 26, such as the shape, are determined appropriately according to design convenience. The wiring section 29 includes power supply wiring that supplies power to at least the motor 1 and the control device 2, and also includes a communication line when performing wired communication based on a protocol such as CAN, LIN, or RS232C. The communication line is not necessary when performing wireless communication such as Bluetooth (registered trademark), Wi-Fi (registered trademark), or ZigBee (registered trademark) or when superimposing a signal on the power supply wiring.

[0069] <Operation and Effect> According to the electric motor device described above, the stator magnetic body 17 has a cavity 17b formed between the location where the excitation coil 3 is provided and the location where it is fixed to the support body Sp. By providing the cavity 17b in the stator magnetic body 17 and increasing the surface area, the amount of heat dissipated until the heat generated by the excitation coil 3 is transferred to the support body Sp is improved, and a temperature rise in the support body Sp is suppressed. By adopting a heat dissipation structure in which the cavity 17b is provided in the stator magnetic body 17, it is not necessary to divide the housing or install a heat sink or the like, and it is possible to achieve simplification and space saving compared to conventional structures that include such a heat sink or the like.

[0070] 3, a plurality of cavities 17b, which are through-holes that penetrate in the axial direction, are provided at equal circumferential intervals in the stator magnetic body 17. The number of the equally spaced cavities 17b is equal to a positive integer multiple of the number of magnetic poles of the stator 4. Of the equally spaced cavities groups 17b1 and 17b2, in the first cavities group 17b1 that is closest to the excitation coil 3, the cavities 17b are provided in the stator magnetic body 17 so that the circumferential position Pc (FIG. 4) of the geometric center of each cavity 17b is located midway between the magnetic poles.

[0071] When the cavities 17b are provided under the above conditions, the magnetic paths separated by the cavities 17b merge with adjacent magnetic poles, making it easier for magnetic flux to pass through. The area where the cavities 17b are provided can also be used as a back yoke, allowing the back yoke to be reduced in size and the heat dissipation area to be further expanded. Furthermore, the stator magnetic body 17 surrounding the cavities 17b also effectively functions as a back yoke, allowing the cavities 17b to be provided closer to the magnetic poles. Therefore, the function of the cavities 17b to suppress heat transfer to the housing 8 and increase heat dissipation can be more effectively achieved. In this embodiment, an example is shown in which the number of cavity groups 17b1 and 17b2 arranged evenly at the same radial position is equal to the number of magnetic poles. However, to achieve the above-described effect, the number of cavity groups arranged evenly at the same radial position may be any integer multiple of the number of magnetic poles. For example, a structure in which finer cavities, such as two or three times the number of magnetic poles, are provided may also be used.

[0072] The stator magnetic body 17 is configured so that at least a portion of the stator magnetic body 17 is connected non-parallel to the radial direction by the first and second cavity groups 17b1 and 17b2. When the cavities 17b are arranged alternately in multiple rows, the heat transfer path from the magnetic pole side where the excitation coil 3, which is the heat source, is located to the support side becomes longer. This extends the heat transfer path from the excitation coil side to the housing side, slowing heat transfer, and the increased surface area increases the amount of heat dissipation. Therefore, heat is more easily dissipated before it reaches the housing 8, making it more difficult for the temperature of the housing 8 to rise.

[0073] 1 includes a housing 8 that supports the bearings 7, 7 together with the stator magnetic body 17. In this case, the amount of heat dissipated from the exciting coil 3 until it is transferred to the housing 8 is improved, making it possible to suppress heat transfer to the bearing 7 more effectively than in a conventional structure that does not employ a heat dissipation structure. This makes it possible to extend the life of the bearing 7 more effectively than in the conventional structure.

[0074] If the components constituting the control device 2 are arranged as described above with reference to Figure 1, the entire electric motor device can be constructed in a space-saving manner. However, the arrangement of the components is only an example, and the actual arrangement can be determined arbitrarily depending on the design. For example, the drive circuit unit 21 and smoothing circuit unit 22 may all be provided on the same board as the control circuit unit 20.

[0075] 1 , heat generated by the exciting coil 3 is transferred to the housing 8 via the stator magnetic body 17, causing the temperatures of the driving circuit 21 and the smoothing circuit 22 to rise together, potentially creating a problem whereby the motor output must be limited to prevent abnormalities in the driving circuit 21 and the smoothing circuit 22. For this reason, if the stator magnetic body 17 is provided with the cavity 17b as described above, the cavity 17b increases the amount of heat transferred from the exciting coil 3 to the housing 8. This prevents the temperature rise in the driving circuit 21 and the smoothing circuit 22. Therefore, the problem of limiting the motor output can be solved.

[0076] <Regarding Other Embodiments> In the following description, parts corresponding to matters previously described in each embodiment are assigned the same reference numerals, and duplicated description will be omitted. When only part of the configuration is described, the other parts of the configuration are the same as those in the previously described embodiment unless otherwise specified. The same configuration produces the same effects. It is possible to combine not only the parts specifically described in each embodiment, but also parts of the embodiments together, provided that there is no particular problem with the combination.

[0077] The field magnet 5 and rotor yoke 10 in Fig. 1 may be fixed together by insert molding or the like, or the field magnet 5 may be molded directly onto the rotor yoke 10 using a material such as a mixture of magnetic powder and resin. The field magnet 5 may be configured in a Halbach array, with magnetic poles parallel to the circumferential direction of the rotation shaft interposed between magnetic poles parallel to the radial direction of the rotation shaft. Alternatively, a ring-shaped magnet may be used for the field magnet 5 and magnetized to the desired magnetic pole. Alternatively, the field magnet 5 may be an embedded magnet type, in which a circular core is formed from laminated electromagnetic steel sheets or a powder magnetic core and a magnet is inserted into a slit that penetrates the core in the direction of the rotation shaft.

[0078] The rotor frame 11 may be molded entirely using resin, or entirely using a metal material, for example. When resin is used for part or the entire rotor frame 11, this resin portion may be insert-molded together with either or both of the rotor yoke 10 and the field magnet 5. The connection between the rotor frame 11 and the rotor yoke 10 and the field magnet 5 may be fixed by adhesive, welding, press-fitting, or the like, in accordance with the respective material configurations or assembly processes, in addition to the insert molding described above.

[0079] Flange portion 12a may be fixed to main shaft 12 as a separate part by screw fastening or the like. As long as the position of main shaft 12 in the rotational axis direction can be restrained, the configuration is not limited to one in which flange portion 12a is provided at one axial end of main shaft 12 and snap ring 15 is provided at the other axial end of main shaft 12. For example, a structure in which rotor frame 11 is fixed to main shaft 12 so that rotor frame 11 abuts against the inner ring end face of bearing 7 on the other axial side (left side in Figure 1 ) may be used. Instead of providing flange portion 12a at one axial end of main shaft 12, the position of main shaft 12 in the rotational axis direction may be restrained by a snap ring that fits into a snap ring groove.

[0080] The rotor frame 11 and the main shaft 12 may have a fixed structure in which they are fixed without providing the rotor fixed terminal 13. As this fixed structure, for example, the rotor frame 11 is press-fitted onto the main shaft 12, the rotor frame 11 and the main shaft 12 are welded together, or a retaining ring groove is provided on the main shaft 12 and a retaining ring is fitted into the retaining ring groove to hold the rotor frame 11 in place.

[0081] The stator magnetic body 17 and the excitation coil 3 may be formed by integrally fixing a group of stator magnetic bodies, each divided into a predetermined pattern and provided with an excitation part. In this case, it is advantageous in that the space between the magnetic poles is smaller and a high-density excitation coil can be formed, compared to a case in which an excitation coil is provided on a single stator magnetic body.

[0082] The coil 3 of the stator 4 may be a distributed winding wound across multiple magnetic poles. The stator magnetic body 17 may consist of only a yoke provided on the inner diameter side of the excitation coil 3, and may be an air-core coil with no stator magnetic body inside the coil. The smoothing circuit unit 22 may be a module in which electrolytic capacitors are connected by wiring bus bars or the like. The smoothing circuit unit 22 may be fixed to the inner circumferential surface of the housing 8 by adhesive or mechanical fitting. The smoothing circuit unit 22 may also be arranged between multiple bearings 7, 7 on the inner circumferential surface of the housing 8.

[0083] <Circuit Configuration> Fig. 5 shows an example of the circuit configuration of the drive circuit unit 21 and the smoothing circuit unit 22. Fig. 5 is not a strict circuit diagram, but a schematic diagram for illustrating the electrical aspects of each element constituting the control device 2. The figure shows a general inverter circuit for driving a three-phase AC motor. VDD and VSS respectively represent a DC voltage source and its reference potential. That is, VDD may be the battery potential, and VSS may be ground.

[0084] The drive circuit 21 is a half-bridge circuit with two switch elements 28 for each phase, and this diagram shows an example in which MOSFETs are used. UH, UL, VH, VL, WH, and WL are input terminals for controlling the respective switch elements 28, and in the case of MOSFETs, these are gate terminals. U, V, and W indicate three-phase power terminals connected to the coils corresponding to each phase. Bipolar transistors or the like may be used for the switch elements 28, and this is determined according to design convenience.

[0085] The smoothing circuit section 22 in this figure is a group of multiple capacitors, and it is preferable to use capacitors with relatively large capacitance, such as electrolytic capacitors, conductive polymer solid electrolytic capacitors, conductive polymer hybrid electrolytic capacitors, etc., as this improves the performance of suppressing power fluctuations. The number of capacitors may be one or any multiple number, regardless of the example in this figure, and is determined based on design considerations such as the trade-off between placement space and cost.

[0086] The control circuit section, not shown in the figure, may include, as necessary, circuit configurations other than the drive circuit section 21 and smoothing circuit section 22 shown in the figure. Examples of the contents include a calculator (microcomputer, FPGA, etc.), a power supply circuit for operating each circuit element including the calculator, a communication control circuit for communication means including commands such as angular velocity and angle, a gate driver having a function for operating the switch element 28 of the drive circuit section 21, and in addition, a relay circuit for cutting off power, a sensor processing circuit, etc. may be provided according to requirements.

[0087] When the drive circuit unit 21 is divided into a number equal to the number of phases and arranged at different circumferential positions, it is easy to ensure a mounting space for the drive circuit unit 21. Because the drive circuit unit 21 is fixed to the outer periphery of the bearing housing 8, it is easy to ensure a mounting space and wiring path for the drive circuit unit 21.

[0088] By locating the smoothing circuit unit 22 facing one axial end of the bearing 7, whose axial position can be easily adjusted, space for mounting the smoothing circuit unit 22 can be secured. Therefore, the entire electric motor device can be configured to save space. As shown in Figure 2, the axial middle position P1 of the area where the multiple bearings 7, 7 are located is offset by a predetermined amount in the axial direction from the axial middle position P2 of the stator 4, in the opposite axial position from the smoothing circuit unit 22. In this case, space for mounting the smoothing circuit unit 22 can be secured efficiently, and the entire electric motor device can be configured to save space.

[0089] <Blade portion> As shown in Fig. 6 , the blade portion 30 has a plurality of blade pieces 300 provided in the circumferential direction around the rotation axis X of the rotor 6. The rotor frame 11 shown in Fig. 1 is coupled to each of the inner diameter side and the outer diameter side of the blade portion 30, and is coupled to the main shaft 12 on the inner diameter side and to the field magnet 5 and rotor yoke 10 on the outer diameter side. In other words, the field magnet 5 and rotor yoke 10 are connected to the main shaft 12 via the blade portion 30. The blade portion 30 extends in the radial direction relative to the rotation axis X.

[0090] The blade portion 30 may be connected to the field magnet 5 and the main shaft 12 indirectly via the rotor frame 11 as shown in FIG. 1, or may be connected directly.

[0091] The blade portion 30 shown in Fig. 6 has a surface that is inclined relative to the direction of rotation, and the rotation of the blade portion 30 constituting the blade group moves air along the inclination. This generates an airflow that passes through the gaps between the blades 300 in a substantially axial direction, functioning as an axial flow fan. This airflow mainly cools the stator 4.

[0092] The shape of the blade portion 30 is not limited to the example shown in Figure 6, and may be configured to any shape that functions as a desired axial fan based on the air volume required for cooling, the motor size, the allowable loss in the blade portion 30, etc. Whether air is fed into the interior of the motor or exhausted from the interior of the motor can be determined appropriately according to design convenience. When air is fed into the interior of the motor through the gaps between the blade pieces 300, 300, the air is exhausted mainly from the openings 9b formed in the outer peripheral surface of the stator frame 9, for example. When air is exhausted from the interior of the motor through the gaps between the blade pieces 300, 300, the air flows in mainly from the openings 9b in the stator frame 9, for example.

[0093] 1 described above, the rotor 5 included in the motor 1 has blade portions 30 connected to the main shaft 12 and the field magnet 5. In this case, as the rotor 5 rotates, an airflow generated by the blade portions 30 cools the stator 4 inside the motor, making it possible to reduce the size of the electric motor device compared to conventional structures that include a cooling fan on the outside of the motor.

[0094] [Second embodiment: axial gap type structure, Figs. 7 to 9C] Fig. 7 shows an example in which an axial gap type stator 4 and rotor 6 are provided instead of the stator and rotor structures of the radial gap type outer rotor structure described above. In this example, the magnetic poles of the rotor 6 face the stator 4 in the direction of the rotation axis of the rotor 6. In other words, the field magnet 5 of the rotor 6 faces the stator 4, which has the rotor magnetic body 17 and the excitation coil 3, across an axial gap in the direction of the rotation axis, which is the left-right direction in Fig. 7.

[0095] On the side opposite to the surface facing the stator magnetic body 17, a rotor yoke 10 is provided adjacent to the field magnet 5 in the direction of the rotation axis. The stator magnetic body 17 is fixed to the housing 8 at its inner diameter side end in a coordinate system in which the rotation axis of the rotor 6 is the axial direction, and is fixed to the stator frame 9 at its end in the direction of the rotation axis. The stator frame 9 supports one axial end 17e of the stator magnetic body 17, which is the right end in FIG. 7. The stator magnetic body 17 has a plurality of protrusions Cp, which become magnetic poles in the direction of the rotation axis, spaced at regular intervals in the circumferential direction, and an excitation coil 3 is wound around each of the protrusions Cp. The winding specifications of the excitation coil 3 are not limited to the example in FIG. 7 and may be any configuration that generates a desired motor torque.

[0096] For example, the excitation coil may be wound in a direction perpendicular to the excitation coil in Fig. 7 between the magnetic poles of the stator magnetic body 17, and the specifications can be determined arbitrarily according to design convenience. Alternatively, instead of winding the excitation coil around the stator magnetic body 17 as in Fig. 7, an excitation coil wound around the rotation axis direction can be arranged facing the rotor, and the stator magnetic body can be provided on the opposite side of the excitation coil from the rotor, making it an air-core coil.

[0097] 8 , a plurality of cavities 17b similar to those in the above-described embodiment are provided in the stator magnetic body 17 at a radial position Pw ( FIG. 9A ) between an inner diameter side portion 17c of the portion fixed to the excitation coil 3 and a portion 17d ( FIG. 9A ) fixed to the housing 8. In addition to these cavities 17b, a plurality of cavities 17b are provided in the stator magnetic body 17 at a rotation axis direction position Pd between a base end portion Pa of the portion fixed to the excitation coil 3 and a portion Pb fixed to the stator frame 9.

[0098] 9A to 9C show the structure of the stator magnetic body 17 and excitation coil of the axial gap motor shown in FIG. 7. As shown in FIG. 9A, an example is shown in which a plurality of elongated cavities 17b are provided in the stator magnetic body 17 at a radial position Pw between an inner diameter side portion 17c of the portion fixed to the excitation coil 3 and a portion 17d of the stator magnetic body 17 fixed to the housing 8 (FIG. 8). These cavities 17b are provided in three different radial rows, each equally spaced around the circumference. The hole shapes and the number of rows may be determined arbitrarily depending on design considerations such as space.

[0099] The cavities 17b may be, for example, triangular or circular holes as in the above-described embodiment. The cavities 17b may be provided in one or two rows at a predetermined radial position, or in four or more rows at a predetermined radial position. Alternatively, as shown in FIG. 9A , multiple cavities 17b may be arranged at equal intervals at predetermined radial positions, or may be irregularly arranged within a predetermined range. In addition to the through-hole cavity shape shown in FIG. 9A , the stator magnetic body 17 may have a groove-like shape with an opening on the inner diameter side, and these through-hole cavities and groove-shaped cavities may be used together.

[0100] 9B and 9C , a plurality of groove-shaped cavities 17b are radially provided between the excitation coil 3 and the axial end face of the stator magnetic body 17. In addition to the cavity shape shown in FIG. 9C , for example, hole-shaped cavities that penetrate from the outer diameter to the inner diameter of the stator magnetic body 17 may be used. These hole-shaped cavities and groove-shaped cavities 17b may be used in combination. Alternatively, a plurality of cavities may be irregularly provided at a predetermined axial position in the stator magnetic body 17.

[0101] As shown in Fig. 7, the stator magnetic body 17 has a notch 17a formed in a portion of its inner diameter side where the drive circuit unit 21 is disposed to avoid interference with the drive circuit unit 21, and the remaining portion is supported in contact with the housing 8 by fitting, adhesive, or the like, as in the above-described embodiment. Alternatively, the right end of the stator magnetic body 17 in Fig. 9B, which is the end in the rotational axis direction, may be fixed to the stator frame 9 in Fig. 7 by adhesive or the like. Either the inner or outer diameter of the portion of the stator magnetic body 17 where the cavity 17b is provided, may be fixed to the housing 8 or the stator frame 9 by fitting, or the like. These fixing structures for the stator magnetic body may be used in combination.

[0102] According to the electric motor device of the second embodiment described above, in an axial gap type electric motor device, the cavity 17b can be easily provided by utilizing the rotational axis direction position and the radial position of the stator magnetic body 17. If the stator magnetic body 17 is configured to be supported on the inner diameter side, a structure in which the cavity 17b is provided on the inner diameter side of the stator magnetic body 17 can be adopted, as in the first embodiment. If the stator magnetic body 17 is configured to be supported at the axial end portion, a structure in which the cavity 17b is provided radially penetrating between the excitation coil 3 and the stator frame 9 at the axial position of the stator magnetic body 17 can also be adopted.

[0103] The structure with the cavity 17b on the inner diameter side and the structure with the cavity 17b penetrating in the radial direction can be used together. By adopting a heat dissipation structure with the cavity 17b in the stator magnetic body 17 in this way, it is possible to achieve simplification and space saving compared to conventional structures equipped with such a heat sink, without requiring the housing to be divided or the installation of a heat sink, etc. Other effects are similar to those of the above-described embodiment. A structure with only one of the cavity 17b on the housing side and the cavity 17b on the fixed frame side may also be used.

[0104] Third Embodiment In the first embodiment, the blade portion 30 may function as a centrifugal fan instead of the axial fan. FIG. 10 shows an example in which a blade portion 30 functioning as a centrifugal fan is provided instead of the blade portion 30 functioning as an axial fan illustrated in FIG. 1 . The blade portion 30 illustrated in FIG. 10 differs from the embodiment illustrated in FIG. 1 in that the blade pieces 300 are shaped to interrupt airflow mainly in the circumferential direction of the rotating shaft and function to generate airflow by discharging air to the outer diameter side through rotation. Rotor frames 11 are provided at both axial ends of the blade portion 30, and the blade portion 30 is connected to the main shaft 12 and field magnets 5 via the rotor frames 11. That is, the blade portion 30 is located between the axial end of the main shaft 12 and the field magnets 5 in the direction of the rotation axis.

[0105] FIG. 11 is a cross-sectional view taken at the position of the blade portion 30 in FIG. 10 , and mainly shows the schematic shape of the blade portion 30 of the rotor 6. Each blade piece 300 of the blade portion 30 has a surface that mainly blocks the airflow in the rotational direction, and functions as a centrifugal fan that exhausts air along the blade piece 300 radially outward from the main shaft by centrifugal force caused by rotation. The shape of the blade portion 30 is not limited to the example shown in FIG. 10 , and can be configured in any shape that achieves the desired centrifugal fan function based on the air volume required for cooling, the motor size, the allowable loss in the blade portion 30, etc. Air is exhausted from inside the motor by the blade portion 30, and air flows in mainly through the openings in the stator frame 9 b shown in FIG. 10 , forming an airflow that passes through the inside of the motor.

[0106] With this configuration, the airflow generated by the blade portion 30 as the rotor 6 rotates cools the stator 4 inside the motor radially, making it possible to reduce the size of the electric motor device compared to conventional structures that have a cooling fan outside the motor 1.

[0107] [Fourth embodiment] In the third embodiment, a radial gap type motor 1 was used in which the magnetic poles of the rotor 6 and the stator 4 face each other in the radial direction of the rotating shaft, but it is also possible to use an axial gap type motor 1 in which the magnetic poles of the rotor 6 and the stator 4 face each other in the axial direction of the rotating shaft. Figure 12 shows a fourth embodiment in which an axial gap type motor is used in an electric motor device of the present invention.

[0108] The field magnet 5 has magnetic poles on its axial end surfaces. A rotor yoke 10 is provided adjacent to the field magnet 5 on the axial side of the field magnet 5. The structures of the field magnet 5 and the excitation coil 3 are basically the same as those in Fig. 1, except that they are shaped to face each other in the axial direction.

[0109] 1, the blade portion 30 is connected to the field magnet 5 and the rotor yoke 10 on the outer diameter side via the rotor frame 11, and is connected to the main shaft 12 on the inner diameter side. That is, the field magnet 5 and the main shaft 12 are connected therebetween via the blade portion 30. The blade portion 30 functions as an axial flow fan that generates an airflow that passes through the rotor 6 in the axial direction as the blade portion 30 rotates. The basic shape and function of the blade portion 30 are almost the same as the blade portion 30 illustrated in FIG. 1, except for the difference in the dimensions of the area where the blade portion 30 is arranged.

[0110] With this configuration, even in an axial gap type motor 1 in which the field magnet 5 of the rotor 6 and the excitation coil 3 of the stator 4 are opposed in the axial direction, the airflow generated by the blade portion 30 as the rotor 6 rotates air-cools the stator 4 inside the motor, making it possible to reduce the size of the electric motor device compared to conventional structures that have a cooling fan outside the motor 1.

[0111] Fifth Embodiment In the fourth embodiment, the blade portion 30 may function as a centrifugal fan instead of an axial fan. FIG. 13 shows an example in which a blade portion 30 having the function of a centrifugal fan is provided. The blade portion 30 illustrated in FIG. 13 differs from the fourth embodiment illustrated in FIG. 12 in that the blade portion has a shape that mainly blocks airflow in the circumferential direction of the rotation axis X and has the function of generating airflow by discharging air to the outer diameter side through rotation. The basic shape and function of the blade portion 30 are substantially the same as those of the blade portion 30 illustrated in FIG. 10, except for the dimensions of the area in which the blade portion 30 is disposed.

[0112] With this configuration, even in an axial gap type motor 1, the airflow generated by the blade portion 30 as the rotor 6 rotates cools the stator 4 inside the motor radially, making it possible to reduce the size of the electric motor device compared to conventional structures that have a cooling fan outside the motor 1.

[0113] In each of the embodiments described above, the motor 1 and the control device 2 may be separate, i.e., the electric motor device may be configured without the control device 2. The electric motor device may also be used for purposes other than vehicles, such as industrial machinery and drones.

[0114] 14 , the electric motor device 105 according to any of the embodiments can also be applied to an electric vertical take-off and landing aircraft (abbreviated as eVTOL) 100. The electric vertical take-off and landing aircraft 100 is a multicopter that has a main body 102 and a plurality of drive units 103 arranged on the front, rear, left, and right sides of the main body 102.

[0115] Each drive unit 103 is a device that generates lift and thrust for the electric vertical take-off and landing aircraft 100. Four arms 102a extend from the main body 102, and a drive unit 103 is provided at the tip of each arm 102a. A skid 102b that supports the aircraft during landing is provided below the main body 102. Each drive unit 103 has a rotor 104 and the electric motor device 105 that rotates the rotor 104.

[0116] This electric vertical take-off and landing aircraft 100 can apply an electric motor device 105 that saves space, making it easier to secure space for arranging the rotors 104, etc., compared to conventional structures, and making it possible to reduce the size and weight of the entire aircraft.

[0117] <Automated Guided Vehicle> The electric motor device according to any of the embodiments can also be applied to an automated guided vehicle. As shown in Fig. 15A, the electric motor device 105 may be applied to an in-wheel motor drive device that independently drives the left and right wheels of an automated guided vehicle 110A. As shown in Fig. 15B, the electric motor device 105 may be applied to an on-board motor drive device that independently drives the left and right wheels of an automated guided vehicle 110B.

[0118] In Figures 15A and 15B, the vehicle automatically transports by automatically calculating accelerator and brake command values ​​based on information from the vehicle's status and various sensors, without relying on driver operation, and then rotating and driving the electric motor device 105 based on these command values. It is also possible to rotate and drive the electric motor device 105 based on accelerator and brake command values ​​corresponding to the driver's operation of the accelerator pedal and brake pedal. In Figures 15A and 15B, electric motor devices 105 are applied to the left and right rear wheels, but electric motor devices 105 may also be applied to the left and right front wheels. Alternatively, an automated guided vehicle may be configured as a four-wheel independently driven automated guided vehicle using electric motor devices 105 for the left and right rear wheels and the left and right front wheels, respectively. The configurations of these automated guided vehicles 110A and 110B allow for the application of space-saving electric motor devices, making it possible to incorporate electric motor devices into existing vehicles without making major structural modifications. This increases the design flexibility of the automated guided vehicle.

[0119] As described above, the preferred embodiment has been described with reference to the drawings, but various additions, modifications, and deletions can be made without departing from the spirit of the present invention. Therefore, such additions, modifications, and deletions are also included in the scope of the present invention.

[0120] The present invention includes the following embodiments 1 to 13, which do not require the cavity 17b.

[0121] [Mode 1] The electric motor device of Mode 1 is an electric motor device comprising a motor including a stator having an excitation coil, a rotor having a field magnet that faces the stator and generates a magnetic force and is rotatably supported relative to the stator, and a control device that controls the motor, wherein at least a portion of the control device is arranged within the motor so as to overlap the field magnet or the excitation coil at an axial position.

[0122] According to the configuration of Aspect 1, at least a portion of the control device is disposed in the motor at an axial position that overlaps with the field magnet or the excitation coil. In this case, the electric motor device as a whole can be configured to take up less space than in conventional structures in which the control device is completely separated from the motor magnetic circuit by the housing.

[0123] [Aspect 2] In Aspect 1, the control device may have a drive circuit unit that controls the energization state of the coil, and at least a portion of the drive circuit unit may be located on the inner diameter side at the same axial position as the field magnet or the excitation coil. The drive circuit unit optionally changes the electrical connection state between the control device's power supply source and the coil. By locating at least a portion of this drive circuit unit on the inner diameter side at the same axial position as the field magnet or the excitation coil, it is possible to reduce the size of the electric motor device.

[0124] [Aspect 3] In Aspect 2, the excitation coil and the field magnet may have different numbers of poles so that the rotor rotates with AC current of a predetermined number of phases, and the drive circuit unit may be divided into a number equal to the number of phases and disposed at different circumferential positions. When the drive circuit unit is divided into a number equal to the number of phases and disposed at different circumferential positions, it is possible to easily ensure a mounting space for the drive circuit unit.

[0125] [Aspect 4] In Aspect 2, the motor may include a bearing that rotatably supports the rotor and a bearing housing that supports the bearing in the same stationary system as the stator, and the drive circuit unit may be fixed to the outer periphery of the bearing housing. In this case, mounting space and wiring paths for the drive circuit unit can be easily secured.

[0126] [Aspect 5] In Aspect 4, the stator may have a notch at a position where the drive circuit is provided to avoid interference with the drive circuit, and the stator may abut against the outer periphery of the bearing housing at a location where the notch is not provided. In this case, the stator can be supported by the bearing housing simply and robustly, and the drive circuit can be easily disposed.

[0127] [Aspect 6] In Aspect 1, the motor may include a bearing that rotatably supports the rotor, and the control device may include a smoothing circuit that suppresses power fluctuations caused by rotating the rotor, the smoothing circuit being disposed facing one axial end of the bearing. The smoothing circuit may be formed, for example, of a relatively large component such as an electrolytic capacitor. By disposing such a smoothing circuit facing one axial end of the bearing, where the axial position can be easily adjusted, space for mounting the smoothing circuit can be secured. Therefore, the entire electric motor device can be configured to save space.

[0128] [Aspect 7] In Aspect 6, the motor may include a bearing housing that supports the bearing in the same stationary system as the stator, and the smoothing circuit unit may be supported by the bearing housing. In this way, the smoothing circuit unit can be provided using the bearing housing.

[0129] [Aspect 8] In Aspect 7, a plurality of the bearings may be provided coaxially with the rotating shaft of the rotor, and the axially intermediate position of the area in which the plurality of bearings are provided may be offset axially opposite the smoothing circuit unit relative to the axially intermediate position of the stator. In this case, space for mounting the smoothing circuit unit can be efficiently secured, and the electric motor device as a whole can be configured in a space-saving manner.

[0130] [Aspect 9] The electric motor device of aspect 9 is an electric motor device equipped with a motor including a stator having an excitation coil, a rotor facing the excitation coil and having a field magnet that generates a magnetic force and is rotatably supported on the stator, and a bearing arranged radially inward of the stator and perpendicular to the rotational axis of the rotor, wherein the rotor has a main shaft rotatably supported by the bearing, and blade portions that are respectively connected to the main shaft and the field magnet and that generate a cooling airflow by rotating around the rotational axis.

[0131] According to the configuration of Aspect 9, the rotor is configured by connecting the field magnet and the main shaft via the blade portion, so the rotor 6 itself has a ventilation function. In this case, compared to when a fan is installed inside the rotor, the stator can be cooled with a space-saving structure, making it possible to reduce the size of the electric motor device.

[0132] [Aspect 10] In Aspect 9, the field magnet may be disposed radially outward of the excitation coil and facing the excitation coil in the radial direction, the blade portion may be located between the radially inner side of the field magnet and the radially outer side of the main shaft when viewed from the direction of the rotation axis, and the field magnet and the main shaft may be connected via the blade portion.

[0133] According to the configuration of aspect 10, in an outer rotor type motor in which the rotor field magnet is arranged radially outward of the stator excitation coil, the stator can be cooled with a space-saving structure, making it possible to reduce the size of the electric motor device.

[0134] [Aspect 11] In Aspect 9, the airflow may pass through the blade portion in the axial direction of the rotor.

[0135] According to the configuration of aspect 11, the blade portion that rotates as part of the rotor functions as an axial fan, and generates an airflow that flows in the direction of the rotation axis, which is directed toward the stator inside the electric motor device, thereby enabling the stator inside the electric motor device to be cooled efficiently and the entire electric motor device to be configured in a space-saving manner.

[0136] [Aspect 12] In Aspect 9, the field magnet and the excitation coil may face each other in the direction of the rotation axis, the blade portion may be located between the field magnet and the axial end of the main shaft in the direction of the rotation axis, and the field magnet and the main shaft may be connected via the blade portion.

[0137] According to the configuration of aspect 12, even in an axial gap type motor in which the field magnet of the rotor and the excitation coil of the stator face each other in the axial direction of the rotating shaft, the stator inside the electric motor can be efficiently cooled by the airflow generated by the blades due to the rotation of the rotor, and the entire electric motor device can be configured to save space.

[0138] [Aspect 13] In Aspect 9, the airflow may be discharged from the blade portion radially outward of the main shaft of the rotor.

[0139] According to the configuration of aspect 13, the blade portion that rotates as part of the rotor 6 functions as a centrifugal fan, and an airflow is generated that flows in the outer diameter direction of the rotor's rotating shaft, and the airflow is directed from the axial center to the outer periphery of the main shaft and stator inside the electric motor device, thereby enabling the interior of the electric motor device to be cooled efficiently and the entire electric motor device to be configured in a space-saving manner.

[0140] REFERENCE SIGNS LIST 1 motor 2 control device 3 excitation coil 4 stator 6 rotor 7 bearing 8 (bearing) housing 9 stator frame 12 main shaft 17 stator magnetic body 17a notch 17b cavity 21 drive circuit section 22 smoothing circuit section 30 blade section Sp support 100 electric vertical take-off and landing aircraft 110A, 110B automatic guided vehicle

Claims

1. An electric motor device comprising a stator having a stator magnetic body and an excitation coil wound around the stator magnetic body, a rotor having magnetic poles facing the stator and supported so as to be freely rotatable relative to the stator, and a support body supporting the stator magnetic body, wherein a cavity is provided in the stator magnetic body between the point where the excitation coil is provided and the point where the stator magnetic body is fixed to the support body.

2. An electric motor device as described in claim 1, wherein the magnetic poles of the rotor face the stator in the radial direction of a coordinate system whose axial direction is the rotation axis of the rotor, the stator magnetic body is fixed to the support at its inner diameter end, and the cavity is provided in the stator magnetic body at a radial position between the inner diameter part of the part fixed to the excitation coil and the part fixed to the support.

3. An electric motor device as described in claim 1, wherein the magnetic poles of the rotor face the stator in the direction of the rotor's rotational axis, the stator magnetic body is fixed to the support at its end in the direction of the rotational axis, and the cavity is provided in the stator magnetic body at a position in the direction of the rotational axis between the base end portion of the part fixed to the excitation coil and the part fixed to the support.

4. An electric motor device as described in claim 1, wherein the magnetic poles of the rotor face the stator in the direction of the rotor's rotational axis, the stator magnetic body is fixed to the support at its inner diameter end in a coordinate system whose axial direction is the rotor's rotational axis, and the cavity is provided in the stator magnetic body at a radial position between the inner diameter part of the part fixed to the excitation coil and the part fixed to the support.

5. An electric motor device as described in claim 2 or claim 4, wherein the stator magnetic body has a plurality of cavities, which are through holes that penetrate the stator magnetic body in the axial direction, arranged at equal circumferential intervals, the number of the evenly spaced cavities being equal to a positive integer multiple of the number of magnetic poles of the stator, and the cavities are arranged in the stator magnetic body such that the circumferential positions of the evenly spaced cavities are located midway between the magnetic poles.

6. An electric motor device according to claim 2 or 4, wherein the stator magnetic body is configured so that at least a portion of the stator magnetic body is connected non-parallel to the radial direction by the cavity.

7. An electric motor device according to claim 2 or 4, further comprising a bearing for rotatably supporting said rotor, said support body including a housing for supporting said bearing together with said stator magnetic body.

8. An electric motor device according to claim 3, wherein said support includes a stator frame which supports one axial end of said stator magnetic body.

9. An electric vertical take-off and landing aircraft comprising the electric motor device according to claim 1 or 2.

10. An automated guided vehicle equipped with the electric motor device according to claim 1 or 2.

11. An electric motor device as claimed in claim 1, further comprising: a motor including a rotor having a field magnet that faces the stator and generates a magnetic force; and a control device that controls the motor, wherein at least a portion of the control device is disposed within the motor so as to overlap with the field magnet or the excitation coil at an axial position.

12. An electric motor device as described in claim 11, wherein the control device has a drive circuit section which controls the energization state of the excitation coil, and at least a part of the drive circuit section is arranged on the inner diameter side at the same axial position as the field magnet or the excitation coil.

13. An electric motor device as described in claim 12, wherein the excitation coil and the field magnet have different numbers of poles so that the rotor rotates with an alternating current of a determined number of phases, and the drive circuit section is divided into a number equal to the number of phases and arranged at different circumferential positions.

14. An electric motor device as claimed in claim 12, wherein the motor comprises a bearing which rotatably supports the rotor, and a bearing housing which supports the bearing in the same stationary system as the stator, and the drive circuit unit is fixed to the outer periphery of the bearing housing.

15. An electric motor device as described in claim 14, wherein the stator has a notch at the position where the drive circuit is provided to avoid interference with the drive circuit, and the stator abuts against the outer periphery of the bearing housing at a location where the notch is not provided.

16. An electric motor device as described in claim 11, wherein the motor is provided with a bearing that rotatably supports the rotor, the control device has a smoothing circuit section that suppresses power fluctuations caused by rotating the rotor, and the smoothing circuit section is arranged to face one axial end of the bearing.

17. An electric motor device according to claim 16, wherein said motor is provided with a bearing housing which supports said bearing in the same stationary system as said stator, and said smoothing circuit section is supported by said bearing housing.

18. An electric motor device according to claim 17, wherein a plurality of the bearings are provided coaxially with the rotating shaft of the rotor, and the axial intermediate position of the area in which the plurality of bearings are provided is offset in the axial direction to a position opposite the smoothing circuit section, relative to the axial intermediate position of the stator.

19. An electric motor device as claimed in claim 1, further comprising a motor including a rotor having a field magnet that faces the excitation coil and generates a magnetic force, and a bearing arranged radially inward relative to the stator and perpendicular to the rotation axis of the rotor, wherein the rotor has a main shaft that is rotatably supported by the bearing, and blade portions that are respectively connected to the main shaft and the field magnet and generate a cooling airflow by rotating around the rotation axis.

20. An electric motor device as described in claim 19, wherein the field magnet is arranged radially outward of the excitation coil and faces the excitation coil in the radial direction, the blade portion is located between the radially inner side of the field magnet and the radially outer side of the main shaft when viewed from the direction of the rotation axis, and the field magnet and the main shaft are connected via the blade portion.

21. An electric motor device according to claim 19, wherein the airflow passes through the blade portion in the axial direction of the rotor.

22. An electric motor device as described in claim 19, wherein the field magnet and the excitation coil face each other in the direction of the rotation axis, the blade portion is positioned between the field magnet and the axial end of the main shaft in the direction of the rotation axis, and the field magnet and the main shaft are connected via the blade portion.

23. An electric motor device according to claim 19, wherein the airflow is discharged from the blade portion radially outward of the main shaft of the rotor.

Images