JP2548475Y2 - Outer rotor type brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an outer rotor type closed brushless motor.

2. Description of the Related Art A motor used for rotating a polygon mirror of a laser printer device or for rotating a disk of an optical disk device or a hard disk device must not release any contaminants such as oil and dust to the outside. Conventionally, brushed DC motors having a sealed structure that can be relatively easily realized have been used in many cases, and contaminants and the like are prevented from being discharged to the outside of the motor from bearings or the like using lubricating oil. In addition, since the brushed DC motor has a sliding wear portion and is poor in reliability, the brushless DC motor has been recently shifted to a sealed brushless motor.

FIG. 2 is a center sectional view of a conventional outer rotor type brushless motor. In FIG. 2, a core 8 constituting a stator and a coil 7 wound around the core 8 are arranged as shown in FIG. The base 12 is fixed by a shaft 9 that is suspended from a mounting surface 12a.

Further, a magnetic sensor 10 composed of a Hall IC or a Hall element for performing magnetic detection is fixed to and incorporated in the shaft body 9 via a mounting member 19 as shown in the figure.

On the other hand, the configuration of the rotor that is rotatably and hermetically sealed by the above-described shaft body 9 and supported by a shaft is provided with a multipolar magnetized annular permanent magnet 2 on the inner peripheral surface of the outer rotor 1 and a cover. A bearing 6 and a seal 5 using magnetic fluid are provided on the body 14 and the outer rotor 1, respectively, so that the rotor is hermetically sealed as shown in the figure.

The conventional hermetic brushless motor configured as described above is configured to control the rotation of the rotor by energizing the coil 7 based on the detection of the rotational position of the rotor by the magnetic sensor 10.

On the other hand, FIG. 3 is a center sectional view of another conventional outer rotor type closed brushless motor. The only difference between the structure of the outer rotor type sealed brushless motor shown in FIG. 3 and the structure of the outer rotor type sealed brushless motor shown in FIG. 2 is the method of disposing the magnetic sensor 10. Therefore, the components shown in FIG. 3 are assigned the same reference numerals as those in FIG. 2, and the description thereof will be omitted, and only different portions will be described.

A lid 40 made of a nonmagnetic material such as aluminum or stainless steel is provided so as to abut the lower end of the permanent magnet 2 as shown in the figure. The magnetic sensor 10 is provided on the mounting surface 12a of the base 12 as shown in the figure, so that the magnetic sensor 10 is not built in the rotor, and consideration is given to reducing the number of parts and the number of assembly steps. I have.

The conventional outer rotor type brushless motor configured as described above detects a change in magnetic flux transmitted from the lower end of the permanent magnet 2 through the lid 40 in the direction of arrow C by the magnetic sensor 10 and rotates the rotor. And the coil 7 is energized based on this position detection to control the rotational drive of the rotor.

[Problems to be solved by the present invention] However, any of the conventional outer rotor type hermetic brushless motors are also configured as described above. Therefore, when the magnetic sensor is built in the rotor,
The problem that the generated torque is small because the total length of the permanent magnet is limited, the problem that the wiring of the magnetic sensor is complicated,
There is a problem that the number of parts and the number of assembling steps are required. Furthermore, when the magnetic sensor is externally mounted, there is a problem that the detection of the magnetic sensor becomes unstable because the magnetization direction of the permanent magnet and the direction of the magnetic flux detected by the magnetic sensor are different.

Therefore, even if the permanent magnet is on the stator side and the coil and the core are configured as a rotor, the magnetization direction of the permanent magnet and the detection direction of the magnetic sensor will be different, so that
In any case, there is a problem that the detection accuracy of the magnetic sensor is reduced.

Therefore, the outer rotor type sealed brushless motor of the present invention has been made in view of the above-described problems, and has as its object the outer rotor type motor that prevents external discharge of contaminants and the like from inside the motor. In the closed type brushless motor, the generated torque does not decrease,
An outer rotor type sealed brushless motor that can simplify the wiring of the magnetic sensor, reduce the number of parts and the number of assembling steps, and can guarantee the detection accuracy of the magnetic sensor for controlling the rotation drive of the outer rotor with high accuracy. The point is to provide.

[Means for Solving the Problems] In order to solve the above problems and achieve the above object, the present invention provides a shaft (9) provided with a stator (8) with a mounting surface (12) of a base (12). 12a) A rotor (1) provided vertically with a sealing means (5) for maintaining the hermetically sealed state with the shaft (9), and provided with a multipolar magnetized permanent magnet (2). Shaft (9)
And an outer rotor made of a magnetic material is rotatably and axially supported in a sealed state, and the outer rotor is rotationally driven by the stator (8) and the permanent magnet (2). An outer rotor type hermetic brushless motor in which rotation position can be detected with high accuracy by magnetic detection means (10) disposed on the mounting surface (12a), wherein the permanent magnet (2) is A non-magnetic cover (4) is provided on the inner peripheral surface of the rotor (1) and opposed to the mounting surface (12a) located below the outer rotor to seal the outer rotor. And a magnetic flux generated by the permanent magnet (2) is formed in the lid (4) so as to form a closed magnetic flux (F) connecting the outer rotor and the magnetic detection means (10). Buried first magnetic body (3) And the closed magnetic flux (F)
The magnetic detecting means (10) is disposed on the mounting surface (12a) so as to be located in the inside.

Preferably, the magnetic detecting means (10) is disposed on the mounting surface (12a) via a second magnetic body (11),
The method is characterized in that the magnetic flux density in the closed magnetic flux (F) is increased to make the detection by the magnetic detection means (10) more reliable.

Preferably, the first magnetic body (3) is divided into some or all of the magnetized poles of the permanent magnet (2) in the inner circumferential direction.

[Operation] The outer rotor type brushless motor according to the present invention has the above-described configuration, and the first rotor is interposed between the permanent magnet and the magnetic detecting means. The magnetic flux change acts to detect the generated magnetic flux change reliably.

In addition, the magnetic detection means provided on the mounting surface via the second magnetic body functions to more reliably detect a change in magnetic flux generated from the permanent magnet when the rotor rotates.

Further, by dividing the first magnetic body into a part corresponding to the number of poles in a part or the entire area in the circumferential direction, the detection is ensured.

[Embodiment] An outer rotor type brushless motor of an outer rotor type according to an embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a center sectional view of the outer rotor type hermetic brushless motor of the embodiment. is there.

In FIG. 1, a core 8 constituting a stator and a coil 7 wound around the core 8 are fixed by a shaft 9 which is suspended from a mounting surface 12a of a base 12 as shown in FIG. I have. A magnetic sensor 10 composed of a Hall IC or a Hall element for detecting a change in magnetic flux is provided at a predetermined position on the mounting surface 12a of the base 12, as shown in the figure.

On the other hand, the configuration of the rotor, which is rotatably and hermetically sealed by the above-mentioned shaft body 9 and is supported, is such that the annular permanent magnet 2 multipolarly magnetized in the direction of arrow A is provided on the inner peripheral surface of the outer rotor 1. At the same time, the rotor, which is provided with the bearing 6 and the seal 5 using the magnetic fluid on the lid 4 and the outer rotor 1, is assembled in the hermetically sealed state as shown in FIG. . The lid 4 is made of a non-magnetic material such as aluminum or stainless steel, and is partially (FIG. 4 (a)) or entirely (FIG. 4 (a)) in the circumferential direction on several magnetized poles of the permanent magnet as shown in FIG. 4 (b) is divided into a ring shape such that the inner peripheral surface of the permanent magnet 2 is substantially in contact with the outer peripheral surface of the first magnetic body 3 as shown in FIG. It is provided.

The magnetic sensor 10 has a second magnetic body 11
And a closed magnetic flux represented by a broken line F is formed. The driver 20 inputs a detection signal from the magnetic sensor 10 and supplies a drive current to the coil 7.

The outer rotor type brushless motor configured as described above energizes the coil 7 based on the rotation position signal of the rotor detected by the magnetic sensor 10 and controls the rotation of the rotor.

As can be understood from the above description, the outer rotor type sealed brushless motor of the embodiment does not incorporate the magnetic sensor 10 inside the rotor, and takes care to reduce the number of parts and the number of assembly steps. Since the magnetization direction of the magnet 2 and the direction of the magnetic flux detected by the magnetic sensor 10 match, the detection of the magnetic sensor 10 can be stabilized.

The permanent magnet 2 is set to the stator side, and the coil 7 and the core 8
Also, when these are configured on the rotor side, the detection accuracy of the magnetic sensor 10 does not decrease.

[Effects of the Invention] As described above, according to the present invention, in the outer rotor type hermetic brushless motor that prevents the contaminants and the like inside the motor from being released to the outside, the generated torque is not reduced, and the magnetic force is reduced. Providing an outer rotor type sealed brushless motor that simplifies sensor wiring, reduces the number of parts and assembly man-hours, and can guarantee the detection accuracy of a magnetic sensor for controlling the rotation of a rotor with high accuracy. it can.

Further, in addition to the above-described effects, it is possible to provide an outer rotor type sealed brushless motor capable of increasing the gain received by the magnetic sensor by reducing the external leakage of the magnetic flux.

Further, in addition to the above-described effects, it is possible to provide an outer rotor-type closed brushless motor that can reduce a magnetic variation and apply a uniform magnetic flux to the magnetic sensor.

[Brief description of the drawings]

FIG. 1 is a center sectional view of an outer rotor type sealed brushless motor of an embodiment, FIG. 2 is a center sectional view of a conventional outer rotor type brushless motor, and FIG. 3 is a conventional outer rotor type sealed. 4 (a) and 4 (b) are external perspective views of the first magnetic body 3. FIG. In the figure, 1 ... outer rotor, 2 ... permanent magnet, 3 ...
1st magnetic body, 4 ... lid, 5 ... seal, 6 ... bearing, 7 ... coil, 8 ... core, 9 ... shaft, 10 ...
Magnetic sensor, 11 Second magnetic body, 12 Base, 12a
Mounting surface, A: magnetizing direction, F: magnetic flux direction.

Claims (3)

(57) [Scope of request for utility model registration] A shaft (9) provided with a stator (8) is vertically suspended on a mounting surface (12a) of a base (12), and a seal for maintaining a sealed state with the shaft (9) is provided. Means (5), and a rotor (1) provided with a multipolar magnetized permanent magnet (2) rotatably and hermetically sealed by the shaft body (9); The stator (8)
And the permanent magnet (2) for rotating the outer rotor, and detecting the rotational position of the outer rotor by magnetic detection means (10) disposed on the mounting surface (12a).
A permanent magnet (2) provided on the inner peripheral surface of the rotor (1), wherein the permanent magnet (2) is provided below the outer rotor. A non-magnetic cover (4) is provided so as to face the mounting surface (12a) to form the outer rotor in the hermetically sealed state, and the magnetic flux generated by the permanent magnet (2) is generated by the outer rotor and the magnetic material. Closed magnetic flux (F) connecting between detecting means (10)
A first magnetic body (3) in the lid (4) so as to form
Wherein the magnetic detection means (10) is disposed on the mounting surface (12a) so as to be positioned within the closed magnetic flux (F). . 2. A method according to claim 1, wherein said magnetic detecting means is provided with a second magnetic body.
The magnetic detection means (10) is disposed on the mounting surface (12a) via 1) to increase the magnetic flux density in the closed magnetic flux (F).
2. The method according to claim 1, further comprising:
2. An outer rotor type hermetic brushless motor according to item 1. 3. The method according to claim 1, wherein the first magnetic body is divided partially or entirely in the inner circumferential direction of a few magnetized poles of the permanent magnet. Outer rotor type brushless motor.