Motor assembly

Abstract

This motor assembly comprises: a motor unit including a rotating shaft, a rotor, and a stator; a driver unit including a circuit board that drives the motor unit; a case that stores the rotor and the stator; and a plurality of bearings that rotatably support the rotating shaft on the case. The rotating shaft includes a first end and a second end. The plurality of bearings include a first bearing and a second bearing. When a direction from the first end toward the second end along the rotating shaft is defined as a first direction, at least a part of the driver unit is disposed at a position inside the case and between the first bearing and the second bearing in the first direction.

Description

Motor Assembly

[0001] This disclosure relates to a motor assembly. This application claims priority based on Japanese Patent Application No. 2024-211167 filed on December 4, 2024, and incorporates all the descriptions set forth in the Japanese application.

[0002] Patent Documents 1 to 3 disclose a motor assembly including a motor unit having a rotating shaft, a rotor, and a stator, and a driver unit including a circuit board for controlling the operation of the motor unit. The rotor and the stator are housed in a case. In the case, a first bearing and a second bearing for rotatably supporting the rotating shaft with respect to the case are arranged. The structure of the motor unit includes a radial gap type structure in which the rotor and the stator are arranged in a direction orthogonal to the rotating shaft, and an axial gap type structure in which the rotor and the stator are arranged in a direction along the rotating shaft. The structure of the motor unit provided in the motor assemblies of Patent Documents 1 to 3 is a radial gap type structure.

[0003] In the motor assemblies of Patent Documents 1 to 3, since the motor unit and the driver unit are arranged in series in the direction along the rotating shaft, the size of the motor assembly in the direction along the rotating shaft tends to be large. Such a motor assembly may be difficult to be arranged in the space depending on the size of the space for installing the motor assembly.

[0004] Japanese Unexamined Patent Application Publication No. 2002-136057, Japanese Unexamined Patent Application Publication No. 2005-192364, Japanese Unexamined Patent Application Publication No. 2009-177869

[0005] The motor assembly of this disclosure comprises a motor section including a rotating shaft, a rotor, and a stator; a driver section including a circuit board for driving the motor section; a case housing the rotor and the stator; and a plurality of bearings rotatably supporting the rotating shaft in the case. The rotating shaft includes a first end and a second end. The stator includes a core and a plurality of coils. The plurality of bearings includes a first bearing positioned closest to the first end and a second bearing positioned closest to the second end. When the direction from the first end to the second end along the rotating shaft is defined as the first direction, at least a portion of the driver section is positioned inside the case and between the first bearing and the second bearing in the first direction.

[0006] Figure 1 is a schematic perspective view of a motor assembly according to Embodiment 1. Figure 2 is a schematic perspective view of a motor assembly according to Embodiment 1 with some components removed. Figure 3 is a cross-sectional view taken along line III-III in Figure 1. Figure 4 is a schematic perspective view of a rotating unit included in the motor assembly of Figure 1. Figure 5 is a schematic perspective view of a first unit included in the motor assembly of Figure 1. Figure 6 is a schematic perspective view of a second unit included in the motor assembly of Figure 1. Figure 7 is a schematic longitudinal cross-sectional view of a motor assembly according to Embodiment 2. Figure 8 is a schematic longitudinal cross-sectional view of a motor assembly according to Embodiment 3. Figure 9 is a schematic diagram of a motor assembly according to Embodiment 4. Figure 10 is a schematic diagram of a motor assembly according to Embodiment 5. Figure 11 is an external view of a motor assembly according to Embodiment 6.

[0007] The inventors considered using a motor section with a small, flattened shape in the direction along the rotation axis as the motor section to be combined with the driver section, in order to create a compact motor assembly in the direction along the rotation axis. A flattened motor section is, for example, a motor section whose size in the direction along the rotation axis is smaller than the outermost diameter of the motor section in a plane perpendicular to the rotation axis.

[0008] In motor assemblies with a flattened motor section, the distance between the first and second bearings supporting the rotating shaft in the case is short. This creates a problem where the rotating shaft is prone to wobbling when the radial load is large. In other words, the allowable radial load of motor assemblies with a flattened motor tends to be small.

[0009] One of the objectives of this disclosure is to provide a motor assembly that is compact in the direction along the length of the rotation axis while easily allowing for a large radial load.

[0010] The motor assembly of this disclosure is compact in the direction along the length of the rotating shaft while easily allowing for a large radial load.

[0011] First, the embodiments of this disclosure will be listed and described.

[0012] <1> The motor assembly of the present disclosure comprises a motor section including a rotating shaft, a rotor, and a stator; a driver section including a circuit board for driving the motor section; a case housing the rotor and the stator; and a plurality of bearings rotatably supporting the rotating shaft in the case. The rotating shaft includes a first end and a second end. The stator includes a core and a plurality of coils. The plurality of bearings include a first bearing positioned closest to the first end and a second bearing positioned closest to the second end. When the direction from the first end to the second end along the rotating shaft is defined as the first direction, at least a portion of the driver section is positioned inside the case and between the first bearing and the second bearing in the first direction.

[0013] The distance between the first and second bearings is determined based on the size and configuration of the rotor and stator. In this specification, the distance between the first and second bearings determined based on the size and configuration of the rotor and stator is referred to as the required distance. If at least a portion of the driver section, including the circuit board, is to be placed between the first and second bearings inside the case, the distance between the first and second bearings must be greater than the required distance. In other words, in the motor assembly of this disclosure, the distance between the first and second bearings is longer than the required distance. A longer distance between the first and second bearings reduces the wobble of the rotating shaft during rotation, thereby increasing the allowable radial load of the motor assembly. Furthermore, by placing at least a portion of the driver section between the first and second bearings, the case does not become excessively large in the first direction, even if the driver section is located inside the case.

[0014] <2> In the motor assembly described in <1> above, at least a portion of the circuit board may be positioned in a location that overlaps with the first bearing in the first direction.

[0015] According to the configuration described in <2> above, the distance between the first and second bearings does not become too long, and the size of the case along the first direction becomes smaller, compared to when the entire circuit board, including the mounted components, is placed between the first and second bearings.

[0016] <3> In the motor assembly described in <1> or <2> above, the first end is an output end connected to the drive target, and the driver unit, the stator, and the rotor may be arranged in that order in the first direction.

[0017] The driven object is the component rotated by the motor. By positioning the rotor far from the output end, the rotating shaft is less likely to wobble during rotation, making it easier to increase the allowable radial load of the motor assembly.

[0018] <4> In the motor assembly described in <1> or <2> above, the first end is an output end connected to the drive target, and the driver unit, the rotor, and the stator may be arranged in the order of the first direction.

[0019] During motor assembly operation, the stator tends to generate heat. If the stator is positioned away from the driver's circuit board, the impact of stator heat on the circuit board can be reduced.

[0020] <5> In the motor assembly described in <1> or <2> above, the stator is a first stator and a second stator that are independent of each other, and the driver unit, the first stator, the rotor, and the second stator may be arranged in the first direction in that order.

[0021] The motor assembly described in <5> above is a single-rotor, double-stator type. In this configuration, there are two stators, resulting in higher torque in the motor section.

[0022] <6> In the motor assembly described in <4> or <5> above, the stator may be fixed so that the surface opposite to the surface facing the rotor is in contact with the inner surface of the case.

[0023] By having the stator, which is prone to generating heat, in contact with the inner surface of the case, the heat dissipation of the stator is improved. As a result, the operation of the motor assembly becomes more stable.

[0024] <7> In the motor assembly described in any of <1> to <6> above, the first end and the second end may each be output terminals connected to different drives.

[0025] The motor assembly configuration of this disclosure makes it easier to increase the allowable radial load. Therefore, even if two different drive objects are connected to both ends of the rotating shaft, those drive objects can be rotated stably.

[0026] <8> In the motor assembly described in any of <1> to <7> above, the driver unit may include a sensor for detecting the rotational position of the rotor.

[0027] The rotor's rotational position can be quickly detected by the sensor, allowing for precise control of the rotor's rotation. The sensor may be a capacitive sensor, an optical sensor, or a magnetic sensor. All of these sensors detect the physical quantities necessary for detecting the rotational position. Alternatively, the sensor may be a software sensor that calculates the rotor's rotational position from the induced voltage generated in the coil in response to changes in the stator's magnetic flux.

[0028] <9> In the motor assembly described in <8> above, the sensor includes an annular sensor magnet fixed to the rotating shaft and a magnetic force sensor that detects changes in the magnetic force of the sensor magnet as the rotating shaft rotates, and the sensor magnet may be positioned between the first bearing and the second bearing in the first direction.

[0029] A sensor including a sensor magnet and a magnetic force sensor is a magnetic sensor. The sensor magnet and magnetic force sensor included in the driver unit are positioned between the first and second bearings, increasing the distance between the first and second bearings. As a result, the runout of the rotating shaft tends to be reduced.

[0030] <10> In the motor assembly described in <9> above, the sensor magnet is arranged to face the circuit board, and the magnetic force sensor may be arranged on the circuit board.

[0031] According to the configuration described in <10> above, it is not necessary to enlarge the case in the radial direction of the rotation axis in order to place the sensor magnet and magnetic force sensor inside the case. The radial direction of the rotation axis is the direction perpendicular to the rotation axis and away from the rotation axis.

[0032] <11> In the motor assembly described in any of <1> to <10> above, the structure of the motor section may be an axial gap type structure in which the stator and the rotor are aligned in a direction along the rotation axis.

[0033] The axial gap type structure makes it easier to manufacture a flattened motor section compared to the radial gap type structure. In the motor assembly configuration of this disclosure, the distance between the first bearing and the second bearing is intentionally made large, so that the allowable radial load can be increased even with an axial gap type core.

[0034] <12> In the motor assembly described in any of <1> to <11> above, the stator may include a connecting board that electrically connects the plurality of coils.

[0035] By incorporating a connection board into the stator, the wiring connecting multiple coils in the stator can be simplified.

[0036] <13> In the motor assembly described in <12> above, the connection board and the circuit board are provided with pins for electrically connecting them, and the pins may be conductors extending along the first direction.

[0037] According to the configuration described in <13> above, the connecting board and the circuit board can be connected simply by bringing them closer together along the axis of rotation.

[0038] <14> In the motor assembly described in any of <1> to <13> above, the core may be a compacted powder molded body.

[0039] In compacted bodies formed by pressure molding of magnetic powder, the magnetic properties of the compacted body can be easily adjusted by changing the type and amount of magnetic powder. Therefore, by forming the core using a compacted body, it is easy to obtain a core with desired magnetic properties.

[0040] Specific examples of the motor assemblies of this disclosure will be described below with reference to the drawings. Identical reference numerals in the drawings indicate the same or corresponding parts. The dimensions of the components shown in each drawing are for illustrative purposes only and do not necessarily represent actual dimensions. The present invention is not limited to these examples, but is indicated by the claims, and all modifications within the meaning and range equivalent to the claims are intended. It should be understood that at least one configuration or feature described in each embodiment and example can be combined with other embodiments and examples, or modified in various ways.

[0041] <Embodiment 1> The motor assembly 1 of this example, shown in Figures 1 to 3, comprises a motor unit 2, a driver unit 3, a case 4, and a plurality of bearings 5. The motor unit 2 is the main component of the motor having a rotating shaft 20. The driver unit 3 controls the operation of the motor unit 2. The case 4 houses a part of the motor unit 2 and a part of the driver unit 3. The plurality of bearings 5 ​​rotatably support the rotating shaft 20 in the case 4. One of the features of the motor assembly 1 of this example is that, as shown in Figure 3, at least a part of the driver unit 3 is arranged in a predetermined position inside the case 4. The components of the motor assembly 1 will be described in order below, followed by a description of the arrangement of the driver unit 3 inside the case 4.

[0042] ≪Motor Section≫ In describing the motor section 2, we will mainly refer to Figure 3, and refer to Figures 2 and 6 as necessary. As shown in Figure 3, the motor section 2 includes a rotating shaft 20, a rotor 7, and a stator 8. The rotating shaft 20 includes a first end 21 and a second end 22 on the opposite side of the first end 21. The first end 21 is an output terminal connected to a drive object (not shown). In this example, the direction from the first end 21 toward the second end 22 is defined as the first direction D1. The direction opposite to the first direction D1, i.e., the direction from the second end 22 toward the first end 21, is defined as the second direction D2.

[0043] In the motor assembly 1 of this example, in the first direction D1, the driver unit 3, the rotor 7, and the stator 8 are arranged in this order. That is, the motor unit 2 of the motor assembly 1 is of a single-rotor single-stator type and has an axial-gap type structure.

[0044] As shown in FIG. 6, the stator 8 of this example includes a core 80 and a plurality of coils 88. The core 80 includes an annular yoke 81 (see FIG. 3) and a plurality of teeth 82 formed in a columnar shape. The plurality of teeth 82 protrude from the surface of the yoke 81 facing the rotor 7 toward the rotor 7 (see FIG. 3). The shapes and sizes of the plurality of teeth 82 are substantially the same. The shape of each tooth 82 is, for example, a substantially prismatic shape or a substantially cylindrical shape. The core 80 is formed, for example, by a powder compact. The powder compact is formed by pressure molding magnetic powder. In the powder compact, it is easy to adjust the magnetic properties of the powder compact according to the type and amount of the magnetic powder. Therefore, by forming the core 80 with a powder compact, it is easy to obtain a core having desired magnetic properties. The core 80 may be formed by one powder compact or may be formed by combining a plurality of powder compacts.

[0045] Each of the plurality of coils 88 is disposed on the outer periphery of each of the plurality of teeth 82. The phases of the alternating currents supplied to the coils 88 adjacent to each other are shifted by, for example, 120°. The stator 8 of this example includes a connection substrate 9 that electrically connects between the plurality of coils 88. The configuration of the connection substrate 9 will be described later. By this connection substrate 9, the wiring connecting between the plurality of coils 88 is simplified.

[0046] As shown in FIG. 3, the rotor 7 is fixed to the rotating shaft 20 and rotates together with the rotating shaft 20. The rotor 7 of this example includes a rotor back yoke 70 and a plurality of rotor magnets 72. As shown in FIG. 4, the rotor back yoke 70 is an annular plate material through which the rotating shaft 20 passes. The rotor back yoke 70 is fixed to the rotating shaft 20, and the rotor back yoke 70 and the rotating shaft 20 rotate coaxially. The rotor back yoke 70 has a base surface 70s facing the stator 8.

[0047] The plurality of magnets 72 for the rotor are fixed to the base surface 70s by, for example, an adhesive or the like. The magnets 72 for the rotor are permanent magnets. The plurality of magnets 72 for the rotor are arranged at substantially equal intervals around the axis of the rotating shaft 20. The magnets 72 for the rotor are magnetized in the direction along the axis of the rotating shaft 20. The magnetization directions of two adjacent magnets 72 for the rotor around the axis of the rotating shaft 20 are opposite to each other. Due to the rotating magnetic field generated in the stator 8, the magnets 72 for the rotor are attracted or repelled by the teeth 82, causing the rotor 7 to rotate with respect to the stator 8.

[0048] The motor unit 2 in this example has a flat shape. Specifically, the size of the motor unit 2 along the rotating shaft 20 is smaller than the outermost diameter of the motor unit 2 in the plane orthogonal to the rotating shaft 20. The size of the motor unit 2 along the rotating shaft 20 is the length from the end face of the rotor 7 on the side opposite to the stator 8 to the end face of the stator 8 on the side opposite to the rotor 7. In this example, it is the length from the end face of the rotor 7 facing the second direction D2 to the end face of the yoke 81 of the stator 8 facing the first direction D1.

[0049] ≪Driver unit≫ As shown in FIG. 3, the driver unit 3 includes a circuit board 30 that drives the motor unit 2. The circuit board 30 may be single or plural. The circuit board 30 includes a drive circuit that supplies power to the coil 88 of the motor unit 2. The circuit board 30 may further include a control circuit that monitors the operation of the motor unit 2 and sends necessary instructions to the drive circuit. A plurality of IC chips, capacitors, resistors, etc. that constitute the circuit are arranged on the circuit board 30.

[0050] Most of the driver unit 3 is housed inside the case 4. Specifically, only a part of the circuit board 30 of the driver unit 3 is arranged outside the case 4, and the other parts are arranged inside the case 4. The part arranged outside the case 4 protrudes outside the case 4 from an opening 40 formed in the peripheral wall of the case 4. A connector portion 30c for connecting an external power source or the like is arranged in the part arranged outside the case 4.

[0051] The driver unit 3 further includes a sensor 33. The sensor 33 may be a capacitive sensor, an optical sensor, or a magnetic sensor. In this example, the sensor 33 is a magnetic sensor including a sensor magnet 35 and a magnetic force sensor 37. The sensor magnet 35 is an annular member fixed to the rotation shaft 20, as shown in Figures 2 and 3. The magnetic force sensor 37 is a member that detects changes in the magnetic force of the sensor magnet 35 as the rotation shaft 20 rotates, as shown in Figures 3 and 5. The sensor magnet 35 is magnetized in a direction perpendicular to the rotation shaft 20. Specifically, when the sensor magnet 35 is viewed from above, half of the annulus is the north pole and the other half is the south pole, as the sensor magnet 35 is magnetized.

[0052] In this example, the rotor 7 and the sensor magnet 35 are positioned between the circuit board 30 and the core 80. Therefore, even if the stator 8 generates heat during the operation of the motor unit 2, the heat from the stator 8 is less likely to affect the circuit board 30.

[0053] ≪Case≫ Case 4 has an internal space for housing the rotor 7 and stator 8 of the motor unit 2. The intermediate portion of the rotating shaft 20 between the first end 21 and the second end 22 is also housed in the internal space of case 4. Most of the driver unit 3 is housed in the internal space. Case 4 is made of, for example, a non-magnetic material. The non-magnetic material may be, for example, a non-magnetic metal such as aluminum, or a resin with excellent rigidity.

[0054] Case 4 in this example is formed by combining a first divided case 41 and a second divided case 42. Both the first divided case 41 and the second divided case 42 are box-shaped, having a bottom with a through hole and an opening on the opposite side of the bottom. A rotating shaft 20 passes through the through hole in the bottom. By combining the first divided case 41 and the second divided case 42 so that the opening of the first divided case 41 and the opening of the second divided case 42 face each other, the above-described internal space is formed inside case 4.

[0055] ≪Bearings≫ In this example, there are two bearings 5 ​​that rotatably support the rotating shaft 20 in the case 4. There may be three or more bearings 5. Of the two bearings 5, the bearing 5 located closer to the first end 21 is called the first bearing 51, and the bearing 5 located closer to the second end 22 is called the second bearing 52.

[0056] Conventionally, the distance between the first bearing 51 and the second bearing 52 was determined to be approximately the minimum possible based on the size of the motor section 2 along the rotating shaft 20. In this example, this distance is referred to as the required distance. However, in a motor assembly 1 equipped with a flattened motor section 2, the required distance tends to be short, and a short required distance tends to reduce the allowable radial load of the motor section 2.

[0057] ≪Arrangement of the Driver Section≫ As shown in Figure 3, in this example, at least a part of the driver section 3 is positioned inside the case 4 and between the first bearing 51 and the second bearing 52 in the first direction D1. More specifically, the sensor magnet 35 of the driver section 3 is positioned between the first bearing 51 and the second bearing 52 (see also Figure 2). As a result, the distance between the first bearing 51 and the second bearing 52 becomes longer than the conventional required distance. Because the distance between the first bearing 51 and the second bearing 52 is longer than the required distance, the rotating shaft 20 is less likely to wobble during rotation, and the allowable radial load of the motor assembly 1 can be increased.

[0058] By positioning at least a portion of the driver unit 3 between the first bearing 51 and the second bearing 52, the case 4 does not become excessively large in the first direction D1, even though the driver unit 3 is located inside the case 4. Furthermore, in this example, the circuit board 30 of the driver unit 3 is positioned in a location that overlaps with the first bearing 51 in the first direction D1. Specifically, a through hole is formed in the circuit board 30, and the first bearing 51 is located inside this through hole. With this configuration, the size of the case 4 along the first direction D1 becomes smaller than if the entire driver unit 3, including the circuit board 30, were positioned between the first bearing 51 and the second bearing 52.

[0059] <<Divided Structure>> The motor assembly 1 in this example, shown in Figure 1, is composed of multiple units. The multiple units in this example are the rotating unit 1R, the first unit 1A, and the second unit 1B. The motor assembly 1 can be completed simply by combining these units in a direction along the length of the rotating shaft 20.

[0060] As shown in Figure 4, the rotating unit 1R is a unit in which the rotating shaft 20 and the rotor 7 are integrated. A sensor magnet 35 is positioned on the surface of the rotor 7 opposite to the base surface 70s, as shown in Figures 2 and 3. The sensor magnet 35 is fixed to the rotating shaft 20 by an annular bracket 34. In Figure 2, the first bearing 51 appears to be integrated with the rotating unit 1R, but the first bearing 51 is not integrated with the rotating unit 1R, but with the first unit 1A, which will be described later.

[0061] The rotor 7 is fixed to the rotation shaft 20 and rotates coaxially with the rotation shaft 20. The rotor back yoke 70 of the rotor 7 is sandwiched between the annular bracket 34 and the flange portion 20f. The rotor magnet 72 of the rotor 7 is pressed in the second direction D2 by a push nut 20n, making it difficult to detach from the rotor back yoke 70. Since the rotor magnet 72 is bonded to the rotor back yoke 70, the push nut 20n is not required.

[0062] The first unit 1A, as shown in Figure 5, is a unit in which the first divided case 41, the circuit board 30, and the first bearing 51 are integrated. The first divided case 41 is a shallow, box-shaped member with a bottom surface. The circuit board 30 is positioned facing the bottom surface. An opening 40 is formed in the peripheral wall of the first divided case 41 at the upper position in the drawing (see Figures 1 and 3 together). The portion of the circuit board 30 in which the connector portion 30c is formed protrudes from the opening 40 to the outside of the first divided case 41.

[0063] On the circuit board 30, the side facing the first direction D1, that is, the side facing the motor section 2 (see Figure 3), is equipped with a socket 92 and a magnetic force sensor 37. The socket 92 comprises a conductive part that is electrically connected to a pin 91 (see Figure 3), which will be described later, and a resin part that covers the outer circumference of the conductive part.

[0064] The magnetic force sensor 37, positioned on the circuit board 30, is located facing the sensor magnet 35, as shown in Figure 3. The magnetic force sensor 37 positioned on the circuit board 30 does not increase the radial size of the motor unit 2. As already mentioned, since the magnetic force sensor 37 is magnetized in the radial direction of the rotation shaft 20, the magnetic force input from the sensor magnet 35 to the magnetic force sensor 37 changes as the rotation shaft 20 rotates. Therefore, the rotational position of the rotation shaft 20 can be determined by analyzing the magnetic force from the sensor magnet 35 detected by the magnetic force sensor 37. Information on the rotational position of the rotation shaft 20 is obtained by the control circuit of the circuit board 30 and used to control the motor unit 2.

[0065] As shown in Figure 6, the second unit 1B is a unit in which the second split case 42, the stator 8, and the second bearing 52 are integrated. The second split case 42 is a shallow box-shaped member with a bottom surface. As shown in Figure 3, the yoke 81 of the stator 8 is fixed so as to be in surface contact with the inner surface 4s of the second split case 42. The core 80, including the yoke 81, is prone to generating heat when the motor unit 2 is driven. Because the yoke 81 is in contact with the inner surface 4s of the bottom surface, the heat from the core 80 can easily escape to the case 4, improving the heat dissipation of the core 80.

[0066] The stator 8 in this example includes a connecting board 9. The connecting board 9 has a circuit that electrically connects a plurality of coils 88. The connecting board 9 simplifies the wiring that connects the plurality of coils 88. The connecting board 9 is positioned to face the end face of the teeth 82 opposite to the end face facing the rotor 7.

[0067] The connecting board 9 has pins 91 that are electrically connected to the socket 92 of the circuit board 30. The pins 91 are conductors that extend from the connecting board 9 toward the circuit board 30. That is, the pins 91 are conductors that extend toward the second direction D2. The number of pins 91 is not particularly limited. The motor assembly 1 in this example is a three-phase synchronous motor and has three pins 91. Each of the three pins 91 corresponds to the U phase, V phase, and W phase.

[0068] When manufacturing the motor assembly 1 having the above-described split structure, the first unit 1A and the second unit 1B are combined so as to sandwich the rotor 7 of the rotating unit 1R. Since the pin 91 on the second unit 1B extends along the first direction D1, simply by combining the first unit 1A and the second unit 1B, the pin 91 on the second unit 1B and the conductive part of the socket 92 on the first unit 1A are electrically connected.

[0069] ≪Other≫ The motor assembly 1 in this example further includes an electromagnetic brake 6 for reducing the rotation of the rotating shaft 20. The electromagnetic brake 6 is of a known configuration. The electromagnetic brake 6 is, for example, a friction brake comprising an excitation coil 61, an armature 62, a brake hub 63, and a coil spring (not shown). The brake hub 63 is fixed to the rotating shaft 20. The armature 62 is pressed against the brake hub 63 by the coil spring. When the excitation coil 61 is energized, the excitation coil 61 generates a magnetic force, causing the armature 62 to move away from the brake hub 63. With such a configuration, when the motor assembly 1 is energized, the armature 62 moves away from the brake hub 63, allowing the rotation of the rotating shaft 20 to proceed. When the power supply to the motor assembly 1 is stopped, the armature 62 comes into contact with the brake hub 63, and the rotation of the rotating shaft 20 is inhibited by frictional force.

[0070] The electromagnetic brake 6 can be attached to the assembly after the rotation unit 1R, the first unit 1A, and the second unit 1B have been combined. The electromagnetic brake 6 may also be integrally formed with any of the units. For example, the brake hub 63 may be integrally formed with the rotation unit 1R, and the excitation coil 61, armature 62, and coil spring may be integrally formed with the second unit 1B.

[0071] The outer circumference of the electromagnetic brake 6 is covered by a cover 60. The cover 60 is box-shaped with a bottom. The cover 60 is fixed to the case 4 such that the opening of the cover 60 faces the outer surface of the case 4.

[0072] <Embodiment 2> The motor assembly 1 of Embodiment 2 will be described based on the longitudinal cross-sectional view in Figure 7. Figure 7 is a longitudinal cross-sectional view of the motor assembly 1 of this example, taken at the position of the rotation axis 20, similar to the motor assembly 1 of Embodiment 1. In Embodiment 2, the differences from Embodiment 1 will be mainly described, and the description of configurations that have the same function as Embodiment 1 will be omitted.

[0073] In the motor assembly 1 of this example, the driver unit 3, stator 8, and rotor 7 are arranged in that order in the first direction D1. The motor unit 2 of the motor assembly 1 is a single-rotor, single-stator type and has an axial gap structure. In the motor assembly 1 of this example, the rotor 7 is positioned far from the first end 21, which is the output shaft. Therefore, the rotating shaft is less likely to wobble during rotation, making it easier to increase the allowable radial load of the motor assembly 1.

[0074] The motor assembly 1 in this example is composed of a rotating unit 1R, a first unit 1A, a second unit 1B, and a third unit 1C. The rotating unit 1R has substantially the same configuration as the rotating unit 1R of Embodiment 1 (see Figure 3). That is, the rotating unit 1R in this example has a configuration in which the rotating shaft 20, the rotor 7, and the sensor magnet 35 are integrated.

[0075] The first unit 1A in this example has substantially the same configuration as the first unit 1A of Embodiment 1 (see Figure 3). That is, the first unit 1A in this example has a configuration in which a circuit board 30 and a first bearing 51 are arranged inside the first divided case 41.

[0076] The second unit 1B in this example has a different configuration from the second unit 1B of Embodiment 1 (see Figure 3). Specifically, the second unit 1B in this example has a configuration in which the stator 8 is arranged inside the second split case 42 which opens in the first direction D1. The second unit 1B in this example does not have a bearing 5.

[0077] The third unit 1C has a configuration in which a second bearing 52 is arranged inside a third divided case 43 that opens in the second direction D2.

[0078] By combining the second unit 1B and the third unit 1C so that the opening of the second divided case 42 aligns with the opening of the third divided case 43, an internal space enclosed by the second divided case 42 and the third divided case 43 is formed. The rotor 7 of the rotating unit 1R is positioned in this internal space.

[0079] <Embodiment 3> The motor assembly 1 of Embodiment 3 will be described based on the vertical cross-sectional view in Figure 8. Embodiment 3 will mainly describe the differences from Embodiment 1, and the description of configurations that have the same function as Embodiment 1 will be omitted.

[0080] In the motor assembly 1 of this example, the driver unit 3, first stator 8A, rotor 7, and second stator 8B are arranged in the order of first direction D1. That is, the motor assembly 1 of this example is a single-rotor, double-stator type and has an axial gap structure. In this configuration, the distance between the first bearing 51 and the second bearing 52 is even greater than in the configuration of Embodiment 1. Also, because it has two stators, the first stator 8A and the second stator 8B, which are independent of each other, the torque of the motor unit 2 is increased. Therefore, the allowable radial load of the motor assembly 1 of this example is higher than in the configuration of Embodiment 1.

[0081] The motor assembly 1 in this example is composed of a rotating unit 1R, a first unit 1A, a second unit 1B, and a third unit 1C. The rotating unit 1R in this example has a configuration in which the rotating shaft 20 and the rotor 7 are integrated. The rotor magnet 72 is positioned to penetrate the rotor back yoke 70. The surface of the rotor magnet 72 facing the first direction D1 faces the end face of the teeth 82 of the third unit 1C. The surface of the rotor magnet 72 facing the second direction D2 faces the end face of the teeth 82 of the second unit 1B.

[0082] The first unit 1A in this example has substantially the same configuration as the first unit 1A of Embodiment 1 and Embodiment 2 (see Figures 3 and 7). That is, the first unit 1A in this example has a configuration in which a circuit board 30 and a first bearing 51 are arranged inside the first divided case 41.

[0083] The second unit 1B in this example has substantially the same configuration as the second unit 1B of Embodiment 2 (see Figure 7). That is, the second unit 1B in this example has a configuration in which the first stator 8A and the connecting board 9 are arranged inside the second split case 42 which opens toward the first direction D1.

[0084] The third unit 1C in this example has substantially the same configuration as the second unit 1B of Embodiment 1 (see Figure 3). That is, the third unit 1C in this example has a configuration in which the second stator 8B, the connecting board 90, and the second bearing 52 are arranged inside the third divided case 43 which opens toward the second direction D2.

[0085] By combining the second unit 1B and the third unit 1C so that the opening of the second divided case 42 aligns with the opening of the third divided case 43, an internal space enclosed by the second divided case 42 and the third divided case 43 is formed. The rotor 7 of the rotating unit 1R is positioned in this internal space.

[0086] The connection board 9 of the second unit 1B and the connection board 90 of the third unit 1C are electrically connected by pins 95 and sockets 96. Pins 95 are conductors extending in the second direction D2. The electrical connection between pins 95 and sockets 96 allows the connection board 90 to be electrically connected to the circuit board 30 via the connection board 9.

[0087] <Embodiment 4> The motor assembly 1 of Embodiment 4 will be described based on the vertical cross-sectional view in Figure 9. Embodiment 4 will mainly describe the differences from Embodiment 1, and the description of configurations that have the same function as Embodiment 1 will be omitted.

[0088] The motor assembly 1 in this example does not have an electromagnetic brake 6 (Figure 3). In this motor assembly 1, the driver unit 3 is located away from the first end 21, which is the output terminal. That is, the stator 8, rotor 7, and driver unit 3 are arranged in the first direction D1. Unlike the illustrated example, the rotor 7, stator 8, and driver unit 3 may be arranged in the first direction D1.

[0089] Even with the configuration in this example, the distance between the first bearing 51 and the second bearing 52 becomes longer than the conventional required distance. As a result, the rotating shaft 20 is less likely to wobble during rotation, and the allowable radial load of the motor assembly 1 can be increased.

[0090] <Embodiment 5> The motor assembly 1 of Embodiment 5 will be described based on the vertical cross-sectional view in Figure 10. Embodiment 5 will mainly describe the differences from Embodiment 1, and the description of configurations that have the same function as Embodiment 1 will be omitted.

[0091] The motor assembly 1 in this example does not include a sensor 33, which consists of an annular bracket 34, a sensor magnet 35, and a magnetic force sensor 37, as shown in Figure 3. Instead, the motor assembly 1 in this example may include a software sensor.

[0092] In the motor assembly 1 of this example, the entire circuit board 30 of the driver unit 3 is positioned between the first bearing 51 and the second bearing 52. Even with this configuration, the distance between the first bearing 51 and the second bearing 52 is longer than the conventional required distance. As a result, the rotating shaft 20 is less likely to wobble during rotation, and the allowable radial load of the motor assembly 1 can be increased.

[0093] <Embodiment 6> The motor assembly 1 of Embodiment 6 will be described with reference to Figure 11. Although the inside of the case 4 is not shown in Figure 11, similar to the configuration of Embodiments 1 to 5, at least a part of the driver unit 3 is positioned between the first bearing 51 and the second bearing 52, and the length between the first bearing 51 and the second bearing 52 is longer than the required distance.

[0094] In the motor assembly 1 of this example, both the first end 21 and the second end 22 of the rotating shaft 20 protrude from the case 4. With this configuration, both the first end 21 and the second end 22 can be used as output terminals.

[0095] <Embodiment 7> The motor section 2 provided in the motor assembly 1 of Embodiments 1 to 6 may be a radial gap type motor section having a flattened shape.

[0096] 1 Motor Assembly 1A First Unit, 1B Second Unit, 1C Third Unit 1R Rotation Unit 2 Motor Section 20 Rotation Shaft, 20f Flange Section, 20n Push Nut 21 First End, 22 Second End 3 Driver Section 30 Circuit Board, 30c Connector Section 33 Sensor 34 Annular Bracket, 35 Magnet for Sensor, 37 Magnetic Sensor 4 Case 4s Inner Surface 40 Opening 41 First Split Case, 42 Second Split Case, 43 Third Split Case 5 Bearing 51 First Bearing, 52 Second Bearing 6 Electromagnetic Brake 60 Cover 61 Excitation Coil, 62 Armature, 63 Brake Hub 7 Rotor 70 Rotor Back Yoke, 70s Base Surface, 72 Magnet for Rotor 8 Stator 8A First Stator, 8B Second Stator 80 Core, 81 York, 82 Teeth, 88 Coil, 9, 90 Connecting board, 91, 95 Pins, 92, 96 Socket, D1 First direction, D2 Second direction

Claims

1. A motor assembly comprising: a motor section including a rotating shaft, a rotor, and a stator; a driver section including a circuit board for driving the motor section; a case housing the rotor and the stator; and a plurality of bearings rotatably supporting the rotating shaft in the case, wherein the rotating shaft includes a first end and a second end; the stator includes a core and a plurality of coils; the plurality of bearings include a first bearing positioned closest to the first end and a second bearing positioned closest to the second end; and when the direction from the first end to the second end along the rotating shaft is defined as the first direction, at least a portion of the driver section is positioned inside the case and between the first bearing and the second bearing in the first direction.

2. The motor assembly according to claim 1, wherein at least a portion of the circuit board is positioned to overlap with the first bearing in the first direction.

3. The motor assembly according to claim 1 or claim 2, wherein the first end is an output end connected to a drive target, and the driver unit, the stator, and the rotor are arranged in that order in the first direction.

4. The motor assembly according to claim 1 or 2, wherein the first end is an output end connected to a drive target, and the driver unit, the rotor, and the stator are arranged in that order in the first direction.

5. The motor assembly according to claim 1 or 2, wherein the stator consists of a first stator and a second stator that are independent of each other, and the driver unit, the first stator, the rotor, and the second stator are arranged in the first direction in that order.

6. The motor assembly according to claim 4 or 5, wherein the surface of the stator opposite to the surface facing the rotor is fixed in contact with the inner surface of the case.

7. The motor assembly according to any one of claims 1 to 6, wherein the first end and the second end are output terminals connected to different drives.

8. The motor assembly according to any one of claims 1 to 7, wherein the driver unit includes a sensor for detecting the rotational position of the rotor.

9. The motor assembly according to claim 8, wherein the sensor includes an annular sensor magnet fixed to the rotating shaft and a magnetic force sensor that detects changes in the magnetic force of the sensor magnet as the rotating shaft rotates, and the sensor magnet is positioned between the first bearing and the second bearing in the first direction.

10. The motor assembly according to claim 9, wherein the sensor magnet is arranged to face the circuit board, and the magnetic force sensor is arranged on the circuit board.

11. The motor assembly according to any one of claims 1 to 10, wherein the structure of the motor section is an axial gap type structure in which the stator and the rotor are aligned in a direction along the rotation axis.

12. The motor assembly according to any one of claims 1 to 11, wherein the stator includes a connecting board for electrically connecting the plurality of coils.

13. The motor assembly according to claim 12, comprising pins for electrically connecting the connecting board and the circuit board, wherein the pins are conductors extending along the first direction.

14. The motor assembly according to any one of claims 1 to 13, wherein the core is a compacted powder body.

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