JPH0747983Y2 - Brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a brushless motor.

[Conventional technology]

Generally, in a brushless motor, for example, a dish-shaped rotor holder is used for a rotor, a ring-shaped rotor magnet is fixed to the inner surface of a rising peripheral wall of the rotor holder, and a stator is provided inside the rotor magnet with a slight gap therebetween. The rotors are arranged so as to face each other, and by energizing the coil wound around the stator, the rotor is rotated by electromagnetic interaction between the stator and the rotor magnet.

In such a brushless motor, an index magnet is attached to the rotor holder, the index magnet is detected by a position sensor to generate an index signal, and the rotation of the rotor is controlled based on the signal.

Thus, in the past, as shown in FIGS. 6 and 7,
The index magnet a is a rotor holder b in the rotor.
It is fitted in the hole portion d of the peripheral wall c. In this case, the magnet a has a cylindrical shape having an axial center in the inner and outer peripheral directions of the rotor holder b, and is magnetized in the axial direction. e
Is a rotor magnet.

Here, since the index magnet a has a specified polarity, when the magnet a is attached to the rotor holder b, the magnet a is positioned using a positioning jig (not shown) and then fixed with an adhesive. Was.

[Problems to be solved by the device]

In the brushless motor described in the conventional technique, a positioning jig must be used, which requires a lot of man-hours and a magnet.
The polarity of a2 is always specified. With the conventional one, the operator cannot visually determine the N pole and the S pole, and the magnet a may be fitted in the hole d in an incorrect state. . further,
The adhesive used for fixing may be squeezed out, and if squeezed out, it is troublesome to wipe off the adhesive.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the related art and to provide a brushless motor that can easily and quickly attach an index magnet to a rotor holder without erroneous orientation.

[Means for Solving the Problems]

In order to achieve the above object, a brushless motor of the present invention has a rotor, a stator, and a magnetic sensor. The rotor is composed of a rotor holder, an annular rotor magnet, and an index magnet, and the rotor holder is dish-shaped. With a rising peripheral wall, a rotor magnet is fixed to the inner surface, and a tapered or stepped hole portion is formed to reduce the opening area in the outer peripheral direction, and the index magnet is formed in the outer peripheral direction. It is formed with a slope or step with a reduced cross-sectional area, is magnetized in that direction, and is fitted in the hole of the peripheral wall, the magnetic sensor is fixed to the hanging wall of the bracket, and the position of the index magnet is fixed. Is detected.

[Action]

In the brushless motor according to the present invention, the peripheral wall of the rotor holder is provided with a graduated or stepped hole portion that reduces the opening area in the outer peripheral direction, and the sectional area in the outer peripheral direction is reduced in the hole portion. Since the index magnet formed with the slope or step is fitted, the index magnet does not come out in the outer peripheral direction, and the rotor magnet is not attached to the inner surface of the peripheral wall of the rotor holder after the index magnet is fitted into the hole. Since it is fixed, the index magnet does not slip out in the inner circumferential direction.

Further, since the index magnet is magnetized in the outer peripheral direction, the cross-sectional area in this direction is reduced, and the index magnet is not symmetrical, it is easy to distinguish the N pole and the S pole, and the rotor holder can be erroneously detected. It is not attached to the surrounding wall.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 shows a spindle motor which is an embodiment of the brushless motor according to the present invention. This spindle motor includes a bracket 2 having a cylindrical portion 1, a rotary shaft 4 rotatably supported by the cylindrical portion 1 via bearings 3 and 3,
A hub 5 fixed to one end of the rotary shaft 4, a rotor holder 6 of a rotor 19 fixed to the other end of the rotary shaft 4, and a rotor magnet 8 fixed to an inner peripheral surface 7a of a peripheral wall 7 of the rotor holder 6. , And a stator 9 fitted onto the cylindrical portion 1.

Further, a hole 10 is provided in the peripheral wall 7 of the rotor holder 6, and an index magnet 11 is fitted in the hole 10. Then, the position of the index magnet 11 is changed to a magnetic sensor such as a Hall IC attached to the hanging wall 17 of the bracket 2.
It is detected at 18. A magnetic disk (not shown) is attached to the hub 5.

As shown in FIG. 2, the index magnet 11 is provided with a gradient whose cross-sectional area decreases in the outer peripheral direction.
That is, the index magnet 11 is a truncated pyramid having a rectangular cross section. On the other hand, the hole portion 10 is also provided with a slope such that the opening area decreases in the outer peripheral direction so as to correspond to the index magnet 11.

Further, in this case, for example, the dimension X of the opening 10a on the outer peripheral side of the hole 10 is set slightly smaller than the height dimension Y on the outer peripheral side of the index magnet 11, and the magnet 11 is press-fitted into the hole 10. The outer peripheral side surface 11a of the magnet 11 can be reliably fixed without an adhesive in a state where the outer peripheral side surface 11a of the magnet 11 does not protrude from the outer peripheral surface 7b of the peripheral wall 7.

Here, in order to manufacture the index magnet 11, as shown in FIG. 4, after forming a rod-shaped body 12 having a trapezoidal cross section,
The rod-shaped body 12 can be easily manufactured by magnetizing it and cutting it into a predetermined size as shown by a broken line in the figure.

Next, FIG. 5 shows a modification of the index magnet 11. FIG. 5 (I) shows the case where the index magnet 11 is formed in a truncated cone shape, FIG. 5 (II) shows the case of a triangular truncated cone shape, and FIG. 5 (III) shows the case of a hexagonal truncated cone shape. is there. 5 (IV) and 5 (V) show an index magnet 11 having a step, unlike the above-mentioned case, and FIG. 5 (IV) shows a flat plate-shaped body 13 and a cubic body. FIG. 5 (V) is composed of large and small disk bodies 15 and 16.
Of course, when the index magnets 11 shown in FIGS. 5 (I) to 5 (V) are used, the hole 10 has a shape corresponding to these shapes.

The shape of the index magnet 11 is, of course,
Of course, the present invention is not limited to the illustrated example.

[Effect of device]

Since the present invention is configured as described above, it has the following effects.

An index is formed on the peripheral wall of the rotor holder, which is provided with a beveled or stepped hole portion that reduces the opening area in the outer circumferential direction, and has a beveled or stepped hole portion that reduces the cross-sectional area in the outer circumferential direction. Since the magnets are fitted, the index magnets do not slip out in the outer peripheral direction, and the rotor magnets are fixed to the inner surface of the peripheral wall of the rotor holder after the index magnets are fitted in the holes, so that the index magnets are arranged in the inner peripheral direction. It does not come out, and secure fixation is achieved.

Further, the index magnet is magnetized in the outer peripheral direction, the cross-sectional area is reduced in this direction, and the so-called symmetrical shape is not formed. Therefore, the N pole and the S pole can be easily discriminated, and the rotor holder can be erroneously detected. The index magnet is not attached to the peripheral wall, and the index magnet is easily attracted to the rotor holder due to its own magnetization and the position can be set, and the index magnet can be easily, quickly and accurately attached to the rotor holder. It is a thing.

[Brief description of drawings]

1 to 4 show an embodiment in which the brushless motor of the present invention is applied to a spindle motor. FIG. 1 is a sectional view, FIG. 2 is an enlarged perspective view of an index magnet, and FIG. 3 is an index. Exploded sectional view showing the relationship between the magnet and the hole of the peripheral wall, FIG. 4 is a perspective view of the method for manufacturing the index magnet, and FIGS. 5 to 5 are enlarged perspective views showing modifications of the index magnet, respectively. FIG. 7 is a perspective view of a rotor showing a brushless motor, and FIG. 7 is an enlarged sectional view of a part of FIG. 2 ... Bracket, 6 ... Rotor holder, 7 ... Peripheral wall,
8: rotor magnet, 9: stator, 10: hole, 11: index magnet, 17: hanging wall, 18: magnetic sensor, 19: rotor.

Claims (1)

[Scope of utility model registration request] 1. A brushless motor having a rotor (19), a stator (9) and a magnetic sensor (18), wherein the rotor (19) comprises a rotor holder (6) and an annular rotor magnet (8). And a magnet (11), and the rotor holder (6) has a dish-shaped rising wall (7).
The peripheral wall (7) has a rotor magnet (8) fixed to the inner surface thereof, and a graduated or stepped hole portion (10) that reduces the opening area in the outer peripheral direction is provided through the index wall. The magnet (11) has a gradient that reduces the cross-sectional area in the outer peripheral direction,
Alternatively, the magnetic sensor (18) is formed stepwise, magnetized in that direction, and fitted in the hole (10) of the peripheral wall (7), and the magnetic sensor (18) is the hanging wall (17) of the bracket (2).
A brushless motor that is fixed to and detects the position of the index magnet (11).