JP6074391B2 - Drive device - Google Patents

Description

The present invention relates to a drive device .

  A motor device having a magnetic sensor for detecting the position of a rotor is known. In such a motor device, energization control is performed on the coil in accordance with the detection signal of the magnetic sensor, and the rotor rotates. Patent Document 1 discloses such a motor device.

No. 7-50865

  When the driven member is rotated by such a motor device, the motor device and the housing containing the driven member or the motor device may resonate at a specific number of rotations to increase noise. If the rotation speed at which such resonance occurs is included in the rotation speed range in which the motor device and the driven member are used, resonance occurs during driving of the driven member, and noise increases.

Therefore, an object of the present invention is to provide a drive device that can shift the number of revolutions at which resonance occurs.

The above object includes a stator around which a plurality of coils are wound, and a rotor having a magnet, and a motor device in which energization of the plurality of coils is controlled , and rotation power of the rotor is transmitted to rotate. An impeller, comprising: first, second, and third magnetic sensors disposed in order in a circumferential direction of the rotor so as to face the rotor, the first, second, and Energization to the plurality of coils is controlled based on the output signal of the third magnetic sensor, the rotor has different polarities at equiangular intervals in the circumferential direction, and when the rotation center of the rotor is the center, The first angular interval between the first and second magnetic sensors is different from the second angular interval between the second and third magnetic sensors, and the stator includes a plurality of coils each wound with the plurality of coils. Teeth of the front, adjacent A plurality of slots formed between the teeth, and at least one of the first and second angular intervals is different from a reference angle obtained by dividing 360 degrees by the number of slots; At least one of the first and second angular intervals can be achieved by a driving device that is smaller than the reference angle .

ADVANTAGE OF THE INVENTION According to this invention, the drive device which can shift the rotation speed which resonance generate | occur | produces can be provided.

FIG. 1 is a cross-sectional view of the motor of this embodiment. FIG. 2 is a front view of the stator. FIG. 3A is an explanatory view of the arrangement position of the magnetic sensor in the conventional example, and FIG. 3B is an explanatory view of the arrangement position of the magnetic sensor employed in the motor of this embodiment. FIG. 4 is an explanatory view of the positional relationship between the magnetic sensor and the stator employed in the motor of this embodiment. FIG. 5A is a graph of an experimental result showing a noise value according to the rotational speed of the motor of the conventional example, and FIG. 5B is a frequency analysis of the total noise of the motor and impeller of the conventional example at a predetermined rotational speed. It is the graph which showed the result. FIG. 6A is a graph of an experimental result showing a noise value according to the rotation speed of the motor of this embodiment, and FIG. 6B is a graph showing the total noise of the motor and the impeller of this embodiment at a predetermined rotation speed. It is the graph which showed the frequency analysis result. FIG. 7A is a graph showing current waveforms applied to a plurality of coils of a conventional motor, and FIG. 7B is a graph showing current waveforms applied to a plurality of coils of the motor of this embodiment. .

  FIG. 1 is a cross-sectional view of the motor M of this embodiment. The motor M houses a housing H, a rotor 20 housed in the housing H, a stator 40, a printed circuit board P, and the like. The rotary shaft 10 is rotatably supported by bearings 62 and 64. The rotor 20 is fixed to the rotating shaft 10. On the outer periphery of the rotor 20, a plurality of permanent magnets 30 are arranged in the circumferential direction. The rotor 20 is made of a magnetic material, for example, an electromagnetic steel plate. A stator 40 is disposed around the rotor 20. A plurality of coils 50 are wound around the stator 40. By energizing the plurality of coils 50, a magnetic field for rotating the rotor 20 is generated around the stator 40. The rotor 20 is rotated by a magnetic attractive force and a magnetic repulsive force acting between the magnetic field generated around the stator 40 and the plurality of permanent magnets 30. Thereby, the rotating shaft 10 rotates. An impeller F is connected to the tip of the rotating shaft 10. The impeller F is an example of a driven member that is driven by the motor M. The impeller F is made of synthetic resin, but may be made of metal.

  The motor M is a three-phase 12-slot inner rotor type brushless motor. The plurality of coils 50 are composed of three phases of U phase, V phase, and W phase. Three magnetic sensors US, VS, WS for generating detection signals corresponding to the phases (U phase, V phase, W phase) of the coil 50 are permanently provided on the surface of the printed circuit board P facing the rotor 20. It arrange | positions so that the magnet 30 may be opposed. These magnetic sensors are, for example, Hall elements. The magnetic sensors US, VS, and WS are sensors for U phase, V phase, and W phase, respectively. The printed circuit board P is electrically connected to a drive control circuit provided outside the motor M. The rotor 20 has eight permanent magnets 30 fixed thereto. In the plurality of permanent magnets 30, adjacent permanent magnets 30 are fixed to the rotor 20 with different polarities facing outward in the radial direction. The permanent magnets 30 are arranged at equiangular intervals.

  FIG. 2 is a front view of the stator 40. The stator 40 includes an annular annular portion 42 assembled to the inner wall surface ring of the housing H, and a plurality of teeth portions (magnetic pole portions) 44 arranged in the circumferential direction protruding from the annular portion 42 toward the radial center. Have. A slot 46 is formed between adjacent teeth portions 44. A synthetic resin insulator (not shown) is attached to the stator 40, and a coil 50 is wound around the outside of the insulator. Thus, the stator 40 has a 12-pole (12-slot) configuration. FIG. 2 conceptually shows the polarity of the rotor 20. As shown in FIG. 2, the rotor 20 has alternately different polarities at equiangular intervals.

Next, before explaining the arrangement positions of the magnetic sensors US, VS, WS employed in the motor M of this embodiment, the arrangement positions of the magnetic sensors US, VS, WS in the conventional example will be described. FIG. 3A is an explanatory diagram of arrangement positions of the magnetic sensors US, VS, WS in the conventional example. In the conventional example, for the magnetic sensors US, VS, WS arranged on the printed circuit board Px, θx, which is the angular interval between the magnetic sensors US, VS when the rotation center of the rotor is the center, and the magnetic sensors VS, The angle interval between WSs is equal to θy. That is, the magnetic sensors US, VS, WS are arranged at equal angular intervals with the same mechanical angle, and the electrical angles are also at equal angular intervals. θx and θy indicate mechanical angles. Further, the magnetic sensors US, VS, WS are arranged at positions facing the slots of the stator. θx and θy are set as follows.
θx = θy = 360 degrees ÷ number of slots (1)
For example, in the case of a stator having 12 slots, both θx and θy are 30 degrees. In addition, each electrical angle between the magnetic sensors US, VS, and WS is 120 degrees. Therefore, the magnetic sensors US, VS, and WS can output detection signals having a phase difference of 120 electrical degrees as the rotor rotates. Based on this detection signal, the coil employed in the conventional motor is energized and the rotor rotates. Θx and θy obtained by the equation (1) are reference angles indicating the angular interval between adjacent magnetic sensors employed in a conventional motor. Hereinafter, in this specification, the angle interval obtained by the equation (1) is referred to as a reference angle.

FIG. 3B is an explanatory diagram of the arrangement positions of the magnetic sensors US, VS, WS employed in the motor M of the present embodiment. In this embodiment, θa between the magnetic sensors US and VS is different from θb between the magnetic sensors VS and WS. In other words, the magnetic sensors US, VS, WS are arranged with unequal mechanical angles and unequal electrical angles. For example, θa and θb are set in the following ranges, respectively.
360 ° ÷ number of slots−359 ° ÷ number of slots ≦ θa, θb ≦ 360 ° ÷ number of slots + 359 ° ÷ number of slots (2)
FIG. 4 is an explanatory diagram of the positional relationship between the magnetic sensors US, VS, WS employed in the motor M of the present embodiment and the stator 40. In the present embodiment, the magnetic sensors US and WS are disposed at positions shifted from the centers of the slots 46 of the stator 40 facing each other, and the magnetic sensors VS are positioned at the centers of the facing slots 46. Specifically, the magnetic sensor US does not face the slot 46, and the magnetic sensor WS faces the slot 46 but is off the center of the slot 46. In this manner, the coil 20 is energized and the rotor 20 rotates based on the detection signals output from the magnetic sensors US, VS, WS arranged at unequal angular intervals. In the example shown in FIGS. 3B and 4, θa is smaller than the reference angle described above, and θb is larger than the reference angle. In both cases of the conventional motor and the motor M of the present embodiment, the magnetic sensors US, VS, WS are disposed at equal distances from the rotation center of the rotor 20.

  FIG. 5A is a graph of experimental results showing noise values according to the number of rotations of a conventional motor. The line segment NAx indicates the total noise value of the motor and the impeller F when the impeller F is driven by the conventional motor. The line segment NMx indicates the noise value of only the conventional motor when the impeller F is driven by the conventional motor. As shown in FIG. 5A, the line segment NMx has a peak value PMx and the line segment NAx has a peak value PAx at a rotation speed r1 near a rotation speed of 2000 r / min, and these noises are temporarily high. The reason is considered that the conventional motor and the impeller F resonate. FIG. 5B is a graph showing the frequency analysis result of the entire noise of the conventional motor and impeller F at a predetermined rotational speed r1. As shown in FIG. 5B, it can be seen that the noise value around 1000 Hz is increased as compared with noise at other frequencies.

  FIG. 6A is a graph of an experimental result showing a noise value according to the number of rotations of the motor M of the present embodiment. A line segment NA indicates an overall noise value of the motor M and the impeller F when the impeller F is driven by the motor M. A line segment NM indicates a noise value of only the motor M when the impeller F is driven by the motor M. As shown in FIG. 6A, compared with the conventional example shown in FIG. 5A, the peak values PM and PA of the line segments NM and NA at the rotational speed r1 are the peak values PMx and PAx in the conventional example described above. It turns out that it is falling. FIG. 6B is a graph showing the frequency analysis result of the overall noise of the motor M and the impeller F of the present embodiment at a predetermined rotational speed r1. As shown in FIG. 6B, it can be seen that the noise value around 1000 Hz is reduced as compared with the conventional example shown in FIG. 5B.

  FIG. 7A is a graph showing current waveforms applied to a plurality of coils of a conventional motor. FIG. 7B is a graph showing current waveforms applied to the plurality of coils 50 of the motor M of this embodiment. As described above, in the conventional motor, since the magnetic sensors US, VS, WS are arranged at equal angular intervals, they are applied to the coils that are energized and controlled based on the detection signals of the magnetic sensors US, VS, WS. The current waveform is also regular. On the other hand, in the motor M of the present embodiment, the angular intervals of the magnetic sensors US, VS, and WS are not uniform, so the waveform of the current applied to the coil 50 is irregular, and the energization timing to the coil 50 is Is irregular. For this reason, the noise characteristics of the motor M of the present embodiment and the motor of the conventional example change, and the rotational speed at which the motor M of the present embodiment and the impeller F resonate is generated by the conventional motor. Can be shifted with respect to the number of rotations.

  For example, when such an impeller F is used within the range of the rotational speed including the rotational speed r1, if the conventional motor is used, resonance occurs and noise increases. However, by using the motor M of this embodiment, resonance at the rotation speed r1 can be suppressed, and noise can be suppressed. Accordingly, the noise can be suppressed by shifting the number of rotations at which resonance occurs by a simple change of changing the angular intervals of the magnetic sensors US, VS, and WS.

  Further, as shown in FIG. 6A, the line segment NM takes a peak value PM1 at a rotational speed slightly lower than the rotational speed r1. However, the peak value PM1 is lower than the peak value PMx of the conventional example. Thus, the peak value of the noise value of the motor M of the present embodiment is suppressed more than the peak value of the noise value of the motor of the conventional example within the range of the predetermined rotational speed. Accordingly, an increase in noise of the motor M is suppressed.

  In order to suppress such noise, it is conceivable to absorb vibrations of the impeller F by interposing rubber or the like between the rotating shaft of the conventional motor and the impeller F. However, according to the motor M of the present embodiment, noise can be suppressed without taking such measures. For this reason, the number of parts can be reduced, and an increase in cost can be suppressed.

  In order to suppress such noise, it is also conceivable that the position of the magnetic sensor is arranged in a direction delayed by an electrical angle while maintaining the magnetic sensors US, VS, WS at equal angular intervals. However, in that case, the motor characteristics may be deteriorated. However, according to the present embodiment, noise can be suppressed without deteriorating motor characteristics.

  In the above embodiment, the magnetic sensors US and WS are disposed at positions slightly shifted from the centers of the slots 46 of the stator 40 facing each other, and the magnetic sensors VS are positioned at the centers of the slots 46 facing each other. However, the present invention is not limited to this, and the magnetic sensor VS may be shifted from the center of the slot 46. The magnetic sensors US, VS, and WS only need to be disposed at a position where at least the rotor 20 can be controlled to rotate.

  In the above embodiment, θa is set smaller than the reference angle and θb is set larger than the reference angle. However, the present invention is not limited to this. For example, only one of θa and θb may be set larger or smaller than the reference angle, and the other may be set as the reference angle. One of θa and θb may be set larger than the reference angle and the other smaller. Both θa and θb may be set larger or smaller than the reference angle. In the above embodiment, at least one of the magnetic sensors US, VS, and WS is disposed at the center position of the slot 46 of the stator 40. However, the present invention is not limited to this, and all the magnetic sensors do not face the stator slots. The two magnetic sensors may be arranged so as to face the slot.

  In the motor M of this embodiment, the number of poles of the rotor 20 is 8 and the number of slots of the stator 40 is 12, but the present invention is not limited to this. The motor M and the impeller F of the present embodiment can be used for, for example, electrical appliances, hot water heaters, vehicles, game machines, machine tools, textile machines, printing machines, etc., regardless of whether they are for business use or home use. Moreover, although the impeller F was demonstrated as an example of the driven member which rotates by the rotational power of a rotor being transmitted, a driven member is not limited to this. For example, the driven member may be a speed reducer, a clutch, a pulley, or the like.

  In addition, when the motor is included in the housing, the motor and the housing may resonate. Even in such a case, by using the motor M of this embodiment as described above, The rotational speed at which resonance occurs can be shifted.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and modifications and changes can be made within the scope of the gist of the present invention described in the claims. Is possible.

Motor M
F impeller (driven member)
US, VS, WS Magnetic sensor 10 Rotating shaft 20 Rotor 40 Stator 44 Teeth part 46 Slot 50 Coil

Claims (1)

A stator around which a plurality of coils are wound;
A rotor having a magnet,
A motor device in which energization of the plurality of coils is controlled ;
An impeller that rotates by transmitting the rotational power of the rotor,
Comprising first, second, and third magnetic sensors disposed in order in the circumferential direction of the rotor so as to face the rotor;
Energization to the plurality of coils is controlled based on output signals of the first, second, and third magnetic sensors,
The rotor has different polarities at equiangular intervals in the circumferential direction,
The first angular interval between the first and second magnetic sensors and the second angular interval between the second and third magnetic sensors when the rotation center of the rotor is the center are different,
The stator has a plurality of teeth portions around which the plurality of coils are wound, and a plurality of slots formed between the adjacent teeth portions,
At least one of the first and second angular intervals is different from a reference angle obtained by dividing 360 degrees by the number of slots;
At least one of the first and second angular intervals is a driving device that is smaller than the reference angle.

Images