JP3548787B2 - Brushless motor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a brushless motor using the rotor and its rotor is suitable for a brushless motor, particularly to blanking Rashiresumota which to detect the rotor position by the magnetic sensor.
[0002]
[Prior art]
Conventionally, as shown in FIG. 6A, an electric blower 1 installed in a vacuum cleaner main body (not shown) is provided with a DC brushless motor 3 in a case unit 2 thereof. It is known that the rotation of the fan 3 rotates the fan 4 to generate a negative pressure for sucking dust.
[0003]
The DC brushless motor 3 includes a circuit board 5 fixed to the case unit 2, a stator 6 fixed to the circuit board 5, a motor shaft 7 rotatably held by the case unit 2, and a motor shaft 7. It includes a fixed rotor 8 and a magnetic sensor 9 fixed to the circuit board 5 so as to face the outer periphery of the rotor 8.
[0004]
As shown in FIG. 4A, the stator 6 includes a stator core 6a provided so as to surround the rotor 8, and an insulating slot holding the stator core 6a and winding the stator winding 6b. 6c.
[0005]
As shown in FIG. 5, the rotor 8 includes a rotor iron core 8a having a columnar shape as a whole, and a plurality (four in this case) of permanent magnets 8b inserted near the outer periphery of the rotor iron core 8a. ing. The rotor core 8a includes a driving core 8c facing the stator core 6a, and a position detecting core 8d protruding downward in the figure from the stator core 6a.
[0006]
As shown in FIG. 6B, a plurality (three in this case) of magnetic sensors 9 are arranged so as to face the outer periphery of the position detecting core 8d at equal intervals, and connect the lead terminals 9a to the circuit board 5. In this state, it is fixed by soldering or the like. The magnetic sensor 9 outputs an output signal to a control circuit (not shown) by a magnetic flux (see an arrow a in FIG. 5) from the rotor 8, and the control circuit detects rotor position information based on the output signal. The rotor 8 is rotated by sequentially exciting the stator windings 6b of the stator 6.
[0007]
[Problems to be solved by the invention]
By the way, in the brushless motor configured as described above, for example, as shown in FIG. 4B, in addition to the magnetic flux from the permanent magnet 8b located on the position detecting core 8b, the driving core 8c Is easily affected by a magnetic change such as a magnetic flux from the permanent magnet 8b located at the position B, and a magnetic flux from the stator winding 6b, which may cause an error in detection accuracy and cause a malfunction of the brushless motor or a reduction in efficiency (power reduction). was there.
[0008]
The present invention for solving the above problems, and give to improve the detection accuracy, and to provide a lube Rashiresumota it is possible to prevent the malfunction and power reduction.
[0010]
[Means for Solving the Problems]
In order to achieve the object, the invention according to claim 1 has a configuration in which a stator core is disposed to face a predetermined distance around a rotor core, and at one of both ends along the axial direction of the rotor core. A position detection core protruding along the axial direction from the end face of the stator core is provided, and the rotor position information detected by the magnetic sensor facing the position detection core at a predetermined interval is provided. A brushless motor that sequentially excites a stator winding based on the rotation of the rotor core to rotate the rotor core, wherein a magnetic force is generated between a driving core part of the rotor core facing the stator core and the position detection core part. The gist is that an insulating part is provided.
[0011]
With the configuration according to this first aspect, the drive core portion and the position detection core portion is less susceptible to one another the influence of the magnetic flux while being partitioned by the magnetic insulating portion, a magnetic sensor for detecting the rotational position Can be efficiently detected.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of a brushless motor of the present invention will be described with reference to the drawings.
[0013]
In FIG. 3A, 11 is an electric blower installed in a vacuum cleaner main body (not shown), 12 is its case unit, 13 is a brushless motor provided in the case unit 12, and 14 is a DC brushless motor. 13 is a fan that generates a negative pressure for sucking dust by rotating by rotation of 13.
[0014]
The DC brushless motor 13 includes a circuit board 15 fixed to the case unit 12, a stator 16 fixed to the circuit board 15, a motor shaft 17 rotatably held by the case unit 12, and a motor shaft 17. It includes a fixed rotor 18 and a magnetic sensor 19 fixed to the circuit board 15 so as to face the outer periphery of the rotor 18.
[0015]
As shown in FIG. 1A, the stator 16 includes a stator core 16a provided so as to surround the rotor 18, an insulating slot holding the stator core 16a and winding a stator winding 16b. 16c.
[0016]
As shown in FIG. 2, the rotor 18 has a rotor core 18a formed by laminating thin iron plates of a predetermined shape so as to have a columnar shape as a whole, and a plurality ( (In this case, four) permanent magnets 18b. The rotor core 18a includes a driving core 18c facing the stator core 16a, a position detecting core 18d protruding downward from the stator core 16a in the drawing, a driving core 18c and a position detecting core 18c. And a magnetic insulating portion 18e located between the iron core portion 18d.
[0017]
The magnetic insulating portion 18e is made of a thin plate having the same shape as the driving core portion 18c and the position detecting core portion 18d, and is made of a material having insulating properties such as stainless steel, copper, aluminum, and nickel.
[0018]
As shown in FIG. 1B, a plurality (three in this case) of magnetic sensors 19 are arranged so as to face the outer periphery of the position detecting core 18d at equal intervals, and connect the lead terminals 19a to the circuit board 15. In this state, it is fixed by soldering or the like. The magnetic sensor 19 outputs an output signal to a control circuit (not shown) by a magnetic flux (see an arrow a in FIG. 2) from the rotor 18, and the control circuit detects rotor position information based on the output signal. The stator winding 16b of the stator 16 is sequentially excited to rotate the rotor 18.
[0019]
At this time, the magnetic flux detected by the magnetic sensor 19 is, as shown in FIG. 1B, the magnetic flux from the permanent magnet 18b located in the detection core 18d partitioned from the driving core 18c by the magnetic insulating part 18e. The rotation position is detected based on this magnetic flux (hereinafter, this magnetic flux is referred to as “magnetic flux for detection”).
[0020]
Further, the magnetic insulating portion 18e blocks magnetic flux from the permanent magnet 18b and magnetic flux from the stator winding 16b (hereinafter, these magnetic fluxes are referred to as "driving magnetic flux") located at the driving core portion 18c. Therefore, it is possible to prevent the drive magnetic flux from being detected as the detection magnetic flux, or prevent the detection magnetic flux from causing a change in the magnetic flux, thereby adversely affecting the detection.
[0023]
【The invention's effect】
As described above, in the brushless motor of the present invention, the magnetic insulating portion is provided between the driving core portion facing the stator core of the rotor core and the position detecting core portion. The detection accuracy can be improved, and malfunction and power reduction can be prevented.

[Brief description of the drawings]
1A and 1B show a brushless motor according to a first embodiment of the present invention, wherein FIG. 1A is a longitudinal sectional view of a main part of the brushless motor, and FIG. 1B is an enlarged sectional view of a part thereof;
FIG. 2 is an external perspective view of the rotor.
3A is a vertical sectional view of the electric blower, and FIG. 3B is a perspective view showing a relationship between a circuit board and a magnetic sensor.
4A and 4B show a conventional brushless motor, wherein FIG. 4A is a longitudinal sectional view of a main part of the brushless motor, and FIG. 4B is an enlarged sectional view of a part thereof.
FIG. 5 is an external perspective view of the rotor.
FIG. 6A is a longitudinal sectional view of the electric blower, and FIG. 6B is a perspective view showing a relationship between a circuit board and a magnetic sensor.
[Explanation of symbols]
16 stator 16a stator core 16b stator winding 17 rotor shaft 18 rotor 18a rotor core 18b permanent magnet 18c driving rotor core 18d detection rotor core 18e ... Magnetic insulation part 19 ... Magnetic sensor (magnetic sensor)

Claims (1)

A position where a stator core is disposed facing the rotor core at a predetermined interval, and protrudes at one of both ends along the axial direction of the rotor core along the axial direction from an end face of the stator core. A detection core portion is provided, and the stator windings are sequentially excited based on rotor position information detected by a magnetic sensor facing the position detection core portion at a predetermined interval, to thereby set the rotor core. In a brushless motor to be rotated, a magnetic insulating portion is provided between a driving core portion of the rotor core facing the stator core and the position detecting core portion.

Images