Rotary driving device

Abstract

To provide a rotary driving device capable of having smaller size and thickness and having a structure excellent in operation stability.SOLUTION: A rotary driving device 1 includes: a rotor 5; a plurality of rotor magnets M2 incorporated in the rotor 5; a stator core 6; and a sensor part 4 capable of detecting a magnetic pole of the rotor magnet M2. The stator core 6 has: salient pole parts 6a which is a multiple of the number of driving phases; a first cutout part 7a which accommodates the sensor part 4; and second cutout parts 7b which accommodate three rollers 3. A wire 8 is wound around the salient pole part 6a, and the rotor 5 is rotated by electrification. The sensor part 4 has a substrate 4a and a plurality of magnetic sensors Hu, Hv, and Hw mounted on the substrate 4a. The rotor magnet M2 and the substrate 4a face each other in a circumferential direction of the rotor 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotary drive device. [Background technology]

[0002] In a rotary drive device, a configuration has been proposed in which current flow is controlled according to the output of a Hall element. For example, a brushless motor in which multiple Hall elements are arranged between the magnetic poles of a stator is known (Patent Document 1: JP 2016-208749 A). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-208749 Summary of the Invention [Problem to be solved by the invention]

[0004] However, a configuration in which a substrate is provided around the entire periphery of the stator, as in Patent Document 1, requires an expensive, large substrate, making it difficult to make the motor smaller and thinner. Also, a configuration in which a Hall element is placed near the stator coil is susceptible to noise in pulse width modulation (abbreviated as PWM), resulting in unstable operation.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a rotational drive device that is small and thin, and has a configuration that is excellent in operational stability. [Means for solving the problem]

[0006] The rotary drive device of the present invention comprises a casing, three or more rollers arranged in the casing at a first interval, a rotor supported by the rollers, a plurality of rotor magnets built into the rotor, a stator core built into the casing, and a sensor unit capable of detecting the magnetic poles of the rotor magnet, wherein the stator core has salient pole portions whose number is a multiple of the number of drive phases, a first cutout portion for accommodating the sensor portion, and a second cutout portion for accommodating each of the rollers, and wherein windings are wound around the salient pole portions, and the rotor rotates when current is applied, and the sensor unit comprises a substrate and a plurality of magnetic sensors mounted on the substrate, and the rotor magnet and the substrate are arranged opposite each other in the circumferential direction of the rotor.

[0007] This configuration allows for a small, thin sensor unit with multiple magnetic sensors located in only one location. Furthermore, by locating the sensor unit away from the stator coil and housing it in the stator core, the configuration is less susceptible to PWM noise, resulting in a configuration with excellent operational stability. Furthermore, this configuration allows for an inner rotor type rotary drive device with a configuration suitable for applications that do not use a shaft.

[0008] The rotary drive device of the present invention comprises a casing, a bearing arranged in the casing, a shaft supported by the bearing, a rotor to which the shaft is fixed, a plurality of rotor magnets built into the rotor, a stator core built into the casing, and a sensor unit capable of detecting the magnetic poles of the rotor magnet, wherein the stator core has salient pole portions whose number is a multiple of the number of drive phases and a first cutout portion that accommodates the sensor unit, windings are wound around the salient pole portions, and the rotor rotates when current is applied, and the sensor unit has a substrate and a plurality of magnetic sensors mounted on the substrate, and the rotor magnet and the substrate are arranged opposite each other in the circumferential direction of the rotor.

[0009] This configuration allows for a small, thin sensor unit with multiple magnetic sensors located in only one location. Furthermore, by locating the sensor unit away from the stator coil and housing it in the stator core, the configuration is less susceptible to PWM noise, resulting in a configuration with excellent operational stability. This configuration also allows for an outer rotor type rotary drive device with a configuration suitable for applications using a shaft.

[0010] As an example, the magnetic sensor is three Hall elements mounted on the circuit board at an electrical angle of 60 degrees, and three-phase drive is performed using the detection signals from the Hall elements. With this configuration, the three Hall elements can be arranged over a range of 120 electrical degrees. Since one stator core salient pole corresponds to an electrical angle of 180 degrees, a sensor unit including three Hall elements can be arranged inside the cutout. This allows the sensor unit to be made smaller.

[0011] As an example, the magnetic sensor is three Hall elements mounted on the substrate, the Hall elements being composed of a first element, a second element, and a third element, the first element and the third element being mounted on a first main surface of the substrate, and the second element being mounted on a second main surface of the substrate. With this configuration, an inverted signal can be obtained without signal processing, allowing the sensor unit to be made smaller.

[0012] As an example, the rotor has an origin magnet disposed thereon, and the sensor unit has an origin detection magnetic sensor mounted on the circuit board at a position facing the origin magnet, and a magnetic encoder mounted on the circuit board at a position facing the rotor magnet. With this configuration, a small magnetic encoder can be used instead of a large absolute encoder, making it possible to make the sensor unit even smaller. [Effects of the Invention]

[0013] According to the present invention, a rotary drive device can be realized that can be made small and thin and has a configuration with excellent operational stability. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic structural diagram showing a first example of a rotation drive device according to this embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along the Y direction of FIG. [Figure 3] FIG. 3 is a schematic cross-sectional view taken along the X direction of FIG. [Figure 4] FIG. 4 is a schematic plan view of the sensor unit according to this embodiment. [Figure 5] FIG. 5 is a schematic development view of the rotor and stator according to this embodiment. [Figure 6] FIG. 6 is a schematic waveform diagram showing an example of a control system signal according to this embodiment. [Figure 7] Fig. 7A is a schematic structural diagram showing a second example of a rotation drive device according to this embodiment, and Fig. 7B is a schematic cross-sectional view taken along the X direction of Fig. 7A. [Figure 8] Fig. 8A is a schematic structural diagram showing a third example of a rotation drive device according to this embodiment, and Fig. 8B is a schematic cross-sectional view taken along the X direction of Fig. 8A. [Figure 9] Fig. 9A is a schematic structural diagram showing a fourth example of a rotation drive device according to this embodiment, and Fig. 9B is a schematic cross-sectional view taken along the X direction of Fig. 9A. [Figure 10] FIG. 10 is a schematic waveform diagram showing an example of a control system signal according to this embodiment. [Figure 11] FIG. 11 is a schematic waveform diagram showing an example of a control system signal according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. A rotary drive device 1 of this embodiment includes a rotor 5, a plurality of rotor magnets M2 built into the rotor 5, a stator core 6, windings 8 wound around salient pole portions 6a of the stator core 6, and a sensor unit 4 capable of detecting the magnetic poles of the rotor magnet M2. The rotor 5 rotates when current is applied to the windings 8.

[0016] Here, to make it easier to explain the positional relationship of each part of the rotary drive device 1, the directions are indicated by arrows X, Y, and Z in the figure. The rotary drive device 1 operates normally in any direction. The axis P1 is the center line when the rotor 5 rotates. In all the figures used to explain the embodiments, members having the same function are given the same reference numerals, and repeated explanations may be omitted.

[0017] First, a rotary drive device 1A of the first example will be described.

[0018] [Example 1] The first example is an inner rotor type rotary drive device 1A. As shown in FIGS. 1 to 3, the rotary drive device 1A has a casing 2 that combines a base 2a and a cover 2b. A stator core 6 is attached and fixed to the base 2a and housed in the casing 2. Three or more rollers 3 are arranged in the circumferential direction at a first interval in the casing 2. A rotor 5 is supported for easy rotation by the three or more rollers 3. A plurality of rotor magnets M2 are arranged on the ring-shaped rotor 5 in a circumferentially aligned state. The rotary drive device 1A of the first example has a structure that does not have a shaft.

[0019] In the examples of FIGS. 1 and 5, three rollers 3 are arranged on the stator core 6. The rollers 3 are formed by fitting a ring-shaped sleeve 3a onto the outer ring of a radial bearing. As shown in FIG. 3, a collar 19a is attached and fixed to the base 2a. The rollers 3 are attached to the collar 19a, and the inner ring of the radial bearing is fixed to the base 2a via the collar 19a with screws 19. This brings the sleeve 3a into contact with the rotor 5, and the rotor 5 is easily supported for rotation by the rollers 3.

[0020] 1 and 5, an origin magnet M1 indicating the origin position is disposed on the rotor 5. In addition, a rotor magnet M2 with 32 poles is disposed on the rotor 5.

[0021] The stator core 6 has salient pole portions 6a, the number of which is a multiple of the number of drive phases, first notched portions 7a, second notched portions 7b, and third notched portions 7c, each of which accommodates a roller 3 therein.

[0022] In the example shown in FIGS. 1 and 5, 18 salient pole portions 6a are formed. There is one first cutout portion 7a and two third cutout portions 7c. An insulator (not shown) is provided on each salient pole portion 6a, and a winding 8 is wound around the insulator. Except for the first cutout portion 7a, the second cutout portion 7b, and the third cutout portion 7c, the area around which the winding 8 is wound is molded with resin to form a molded portion. Note that for ease of explanation, the winding 8, the molded portion, and other parts are partially omitted in FIG. 1.

[0023] 1 and 5, the sensor unit 4, which can detect the magnetic poles of the origin magnet M1 and the rotor magnet M2, is housed in the first cutout portion 7a. As shown in FIG. 4, the sensor unit 4 includes a magnetic sensor Ho, a magnetic encoder He, a magnetic sensor Hu, a magnetic sensor Hv, and a magnetic sensor Hw mounted on a substrate 4a. The magnetic sensor Ho is an origin sensor mounted in a position facing the origin magnet M1. The magnetic sensor Hu is a first Hall element, the magnetic sensor Hv is a second Hall element, and the magnetic sensor Hw is a third Hall element.

[0024] The sensor unit 4 is arranged such that the rotor magnet M2 and the substrate 4a face each other in the circumferential direction of the rotor 5. The magnetic sensors Hu, Hv, and Hw are mounted on the substrate 4a at an electrical angle pitch of 60 degrees, and three-phase drive is performed using the detection signals from these Hall elements.

[0025] FIG. 6 is a schematic waveform diagram showing an example of control system signals according to this embodiment. This embodiment is a three-phase drive, and the three-layer winding 8 consists of a winding 8u corresponding to the U phase, a winding 8v corresponding to the V phase, and a winding 8w corresponding to the W phase. The sensor unit 4 has a Hall element Hu that detects the magnetic pole when current is applied to the winding 8u, a Hall element Hv that detects the magnetic pole when current is applied to the winding 8v, and a Hall element Hw that detects the magnetic pole when current is applied to the winding 8w. The Hall elements Hu, Hv, and Hw are mounted on the substrate 4a at intervals of 60 degrees electrical angle K1, and three-phase drive is performed using the detection signals from each Hall element.

[0026] Next, a second example of a rotational drive device 1B will be described.

[0027] [Example 2] The second example is an outer rotor type rotary drive device 1B. As shown in Figures 7A and 7B, rotary drive device 1B includes a base 12, a bearing 13 arranged in base 12, a shaft 11 supported by bearing 13, a rotor 15 to which shaft 11 is fixed, a plurality of rotor magnets M2 built into rotor 15, a stator core 16 arranged in base 12, and a sensor unit 4 capable of detecting the magnetic poles of rotor magnets M2. Stator core 6 is attached and fixed to base 2a and built into the casing. The plurality of rotor magnets M2 are arranged on the inner wall of rotor 5 in a circumferentially aligned state.

[0028] The stator core 16 has salient poles 16a (number of salient poles equal to a multiple of the number of drive phases) and first cutouts 17a (notches) for accommodating the sensor unit 4. A winding 8 is wound around each salient pole 16a, and the rotor 15 rotates when current is applied. The sensor unit 4 is attached to the base 12, and the rotor magnet M2 and the substrate 4a are arranged facing each other around the circumference of the rotor 15. The magnetic sensors Hu, Hv, and Hw are mounted on the first main surface of the substrate 4a at 60-degree electrical angle intervals, and three-phase drive is performed using detection signals from these Hall elements. The magnetic encoder He is mounted on the second main surface of the substrate 4a. Figures 10 and 11 are schematic waveform diagrams showing examples of control system signals according to this embodiment.

[0029] Next, a description will be given of a rotation drive device 1C of the third example. Note that in the third example, the description of the parts common to the second example will be omitted and only the characteristic parts will be described below.

[0030] [Example 3] The third example is an outer rotor type rotary drive device 1C. As shown in FIGS. 8A and 8B, the sensor unit 4 in the rotary drive device 1C has magnetic sensors Hu and Hw mounted on the first main surface of the substrate 4a at an electrical angle of 120 degrees. The magnetic sensor Hu is mounted on the second main surface of the substrate 4a, and three-phase drive is performed using detection signals from these Hall elements. The magnetic encoder He is mounted on the first main surface of the substrate 4a.

[0031] Next, a description will be given of a rotation drive device 1D of the fourth example. Note that in the fourth example, the description of the parts common to the second example will be omitted and only the characteristic parts will be described below.

[0032] [Example 4] The fourth example is an outer rotor type rotary drive device 1C. As shown in Figures 9A and 9B, the sensor unit 4 in rotary drive device 1D has magnetic sensors Hu, Hv, and Hw mounted on the first main surface of substrate 4a at an electrical angle of 60 degrees, and three-phase drive is performed using detection signals from these Hall elements. A magnetic encoder He is mounted on the first main surface of substrate 4a.

[0033] According to this embodiment, the stator core 6 is cut out in a number of places that is a multiple of the number of phases of the drive unit, so that torque ripple and vibration due to the cutouts do not occur. By arranging the substrate 4a, on which the Hall elements Hu, Hv, and Hw, which are magnetic pole position detection sensors, are mounted, in one of these cutout places, components such as sensors can be placed in the space defined by the rotor 5, stator core 6, and rotor, thereby saving space.

[0034] According to this embodiment, the sensor unit 4 is located away from the stator coil, making it less susceptible to PWM drive noise. The rotor 5 has a ring-shaped rotor yoke made of soft magnetic metal, and a ring-shaped rotor magnet M2, divided into 32 poles, fixed to the outer periphery by adhesive or other means. Magnetizing the rotor yoke to multiple poles makes it possible to reduce the radial thickness of the rotor yoke, reducing inertia and improving responsiveness during acceleration and deceleration.

[0035] In the above-described embodiment, the winding section has 18 poles, and the windings 8 of the U, V, and W phases are wound on every six poles in the order of, for example, U1, U2. At the crossover portion of the stator core 6 for each phase, a coil guide is provided extending in the circumferential direction on the outer periphery of the stator coil, and the windings 8 are routed on the outer periphery of the coil guide, thereby stably connecting the multiple windings 8 together.

[0036] In the above-described embodiment, an origin magnet M1 is disposed near one of the N poles of the rotor magnet M2 (the left end in FIG. 5) so that its N pole of the same polarity faces the stator core 6. A stator core 6 having a notch is disposed radially opposite the rotor magnet M2. At least one of an origin sensor Ho, a rotor magnet magnetic pole sensor, and a magnetic encoder He is mounted on the substrate 4a that constitutes the sensor unit 4. The origin sensor Ho is a Hall element that detects the rise in the magnetic field change caused by the magnetic field of the origin magnet M1 being added to the N pole peak of the rotor magnet M2, which changes sinusoidally once per rotation of the rotor 5 as the origin magnet M1 passes by.

[0037] The magnetic encoder He has multiple Hall element chips embedded in a package, and outputs encoder signal A and encoder signal B, which are output 1024 times per rotation of the rotor 5, based on changes in the magnetic field of the rotor magnet M2, which is divided into 32 poles. There is a 90° phase difference between the A and B phases of the encoder signal, so per rotation of the rotor 5, 4096 encoder signals, multiplied by 4, are obtained. Using the magnetic encoder He enables precise speed control, position control, and discrimination between forward and reverse rotation.

[0038] According to the above-described embodiment, for example, the operation of accelerating, constant speed, and decelerating is repeated several tens of times, and then the rotation direction is reversed and the same operation of accelerating, constant speed, and decelerating is repeated, and then this operation of rotating forward and reversing is repeated again, and this operation of rotating forward and reversing again can be performed with high precision and high speed. The specifications of the above-described rotary drive device 1 may be modified as appropriate depending on the specifications, etc. The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0039] 1, 1A, 1B, 1C, 1D Rotational drive unit 2 Casing, 2a Base, 2b Cover, 2c Overlap 3 rollers, 3a sleeve 4 sensor unit, 4a substrate 5 rotors 6 stator core, 6a salient pole 7a First notch, 7b Second notch, 7c Third notch 8, 8u, 8v, 8w winding 11 Shaft 12 base 13 Bearings 15 rotors 16 stator core, 16a salient pole portion 17a First notch, 17c Third notch 19 screw, 19a collar Ho magnetic sensor (origin sensor) He magnetic encoder Hu magnetic sensor (first hall element) Hv magnetic sensor (second Hall element) Hw Magnetic sensor (third Hall element) K1 Electrical angle K2 mechanical angle M1 origin magnet M2 rotor magnet P1 axis

Claims

1. a casing, three or more rollers arranged in the casing at a first interval, a rotor supported by the rollers, a plurality of rotor magnets built in the rotor, a stator core built in the casing, and a sensor unit capable of detecting the magnetic poles of the rotor magnet, wherein the stator core has salient pole portions the number of which is a multiple of the number of drive phases, first notches for accommodating the sensor portion, and second notches for accommodating the rollers, and a winding is wound around the salient pole portions, and the rotor rotates when current is applied; the sensor unit has a substrate and a plurality of magnetic sensors mounted on the substrate, and the rotor magnet and the substrate are arranged to face each other in the circumferential direction of the rotor. A rotary drive device characterized by:

2. The rotor comprises a casing, a bearing disposed in the casing, a shaft supported by the bearing, a rotor to which the shaft is fixed, a plurality of rotor magnets housed in the rotor, a stator core housed in the casing, and a sensor unit capable of detecting the magnetic poles of the rotor magnet, the stator core having salient pole portions the number of which is a multiple of the number of drive phases and a first cutout portion for accommodating the sensor unit, windings are wound around the salient pole portions, and the rotor rotates when current is applied, the sensor unit having a substrate and a plurality of magnetic sensors mounted on the substrate, the rotor magnet and the substrate are disposed opposite to each other in the circumferential direction of the rotor A rotary drive device characterized by:

3. The magnetic sensor is composed of three Hall elements mounted on the board at an electrical angle of 60 degrees, and three-phase drive is performed using detection signals from the Hall elements.

3. The rotary drive device according to claim 1 or 2,

4. The magnetic sensor is three Hall elements mounted on the substrate, the Hall elements being composed of a first element, a second element, and a third element, the first element and the third element being mounted on a first main surface of the substrate, and the second element being mounted on a second main surface of the substrate.

3. The rotary drive device according to claim 1 or 2,

5. The rotor has an origin magnet disposed thereon, and the sensor unit has an origin detection magnetic sensor mounted on the circuit board at a position facing the origin magnet, and a magnetic encoder mounted on the circuit board at a position facing the rotor magnet.

3. The rotary drive device according to claim 1 or 2,

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