JPS62230345A - Brushless motor - Google Patents

Abstract

PURPOSE:To arrange the outer circumferential surface of a rotor and position detecting elements oppositely by removing partial magnetic poles, compensating the removed magnetic poles by each phase coil and disposing the position detecting elements into pole spaces from which the magnetic poles arc taken away. CONSTITUTION:A plurality of magnetic poles 37a are projected inward from a ring-shaped base section in a stator core 37, and the stator core 37 is formed to a shape that three poles are gotten rid of in predetermined order in magnetic poles of twelve poles. Coils are wound on residual each magnetic pole 37a in the stator core 37, but the phase of respective coil is disposed as if the removed magnetic poles were present. Hall ICs 43 as elements detecting the revolution of a rotor are fitted into pole spaces, from which the stator core 37 is removed, through Hall IC holders 45.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a brushless motor, and particularly to an arrangement structure of elements for detecting rotation of a rotor of a brushless motor.

(Prior Art) DCC brushless motors are used as spindle drive motors for backup storage devices such as computers. DCC brushless motors for such applications are required to rotate at high speed, and are also required to have instant starting and stopping characteristics in order to repeat starting and stopping. In addition, there is a demand for thinner motors due to the thinner storage devices, and low inertia inner rotor type flat DC brushless motors are being studied. Furthermore, the motor for driving the spindle of the storage device is required to be equipped with, for example, a tacho generator that generates several pulses per revolution in order to control the rotational speed.

In order to meet these demands, a brushless motor having a structure as shown in FIGS. 13 to 16 has been proposed. However, these brushless motors are not yet known.

First, the brushless motor shown in FIGS. 13 to 15 will be explained. This motor has a stator with 12 slots and a rotor with 8 magnetic poles. In FIGS. 13 to 15, a cup-shaped case 1
A mounting plate 12 is fixed to the open end of the shaft 1 through the case 11 and the mounting plate 12 through bearings 14 and 15.
3 is rotatably held. A cab stan 16 is attached to the end of the shaft 13 protruding from the mounting plate 12 side. A stator core 17 is fixed to the inner peripheral side of the case 11. The stator core 17 has a plurality of magnetic poles 17a, and a coil 18 is wound around each of these magnetic poles 117a. A magnet holder 19 having a rotor magnet 20 fixed to its outer periphery is fixed to the shaft 13, and the rotor magnet 20 is attached to the stator core together with the holder 19.
It is designed to be able to rotate freely on the inner circumference side of 7. A circuit board 22 to which a Hall TC 23 is connected is attached to the inner bottom of the case 11. The Hall IC 23 faces the lower end surface of the rotor magnet 20. A tacho generator magnet 21 is fixed to the lower end surface of the magnet holder 19, and this magnet 21 faces a power generation coil pattern printed on a circuit board 22. A portion of the circuit board 22 protrudes outward from a hole 11a formed in the case 11, and a lead wire 24 is connected to the protrusion of the circuit board 22.

The above brushless motor has the following problems.

(1) The drive magnet and the tachogenerator magnet are separate, and because they are assembled into one, the rotor becomes expensive.

(2) Less magnetic flux exits from the end face of the drive magnet,
Since this small magnetic flux is picked up to operate the Hall IC, the output waveform of the Hall IC has poor sharpness.
ineffective.

(3) It is necessary to adjust the gap between the Hall IC and the drive magnet and the gap between the tacho generator magnet and the circuit board, and it is difficult to adjust both.

(4) The Hall IC may malfunction due to magnetic flux leakage from the stator.

(5) The stator core and Hall IC must be positioned visually or by alignment with a jig.

(6) It is necessary to form a long hole on the side of the case to serve as an outlet for the circuit board, but since the circuit board is fixed to the inner bottom of the case by adhesive, it is necessary to make it fit tightly.
The elongated hole in the case must be formed so that there is no protrusion from the bottom of the case, which is cumbersome to process (see FIG. 15).

(7) The area of the circuit board becomes large (which causes an increase in cost).

(8) The case and mounting plate are caulked, and when the motor is attached to various types of equipment, it is necessary to release the protruding portion of the caulked portion, which requires a large amount of installation space.

In order to solve many of these problems, a brushless motor as shown in FIG. 16 has been proposed. The first point in which the brushless motor shown in FIG. 16 differs from the brushless motor described above is that the driving magnet and the tachogenerator magnet are integrally molded with a plastic magnet, and this is used as the rotor magnet 25. This solves the problem 1) mentioned above. In addition, in order to solve the problems (6) and (7), the circuit board 26
was fixed to the mounting plate 12 side, and the lead wires were soldered inside the motor through the circuit board 26 and the mounting plate 12. For this reason, the holes for the lead wires can be formed by pressing, the circuit board can be made smaller, and the lead wires can be fixed inside the motor, so the installation space for the motor can be made smaller. I can do it.

(Problems to be Solved by the Invention) However, even in the brushless motor shown in FIG. 16, the problems (2) to (5) are still unsolved. Moreover, in the brushless motor shown in FIG. 16, it has become even more difficult to eliminate the drawback (5). That is, since the mounting plate having the circuit board is fitted into the case after the stator core is fixed to the case, the positional relationship between the Hall IC and the stator core is determined when the stator core is fixed to the case.

In addition, the stator coil lead wires are soldered to the circuit board before fitting the mounting plate to the case, so when fitting the mounting plate to the case, the lead wires may become slack and touch the rotor. , there is a risk that the lead wire may be caught between the case and the mounting plate.

The present invention has been made to solve the above-mentioned problems, and makes it possible to arrange a rotation detection element facing the outer peripheral surface of the rotor so that a rotor commutation signal can be reliably obtained. Another object of the present invention is to provide a brushless motor that can be made thinner and lighter by easily obtaining a mounting space for a hole tC.

(Means for Solving the Problems) In the brushless motor according to the present invention, some of the plurality of magnetic poles are removed, and the remaining magnetic poles have a removing force.
The stator is characterized by comprising a stator in which coils of each phase are wound in the order as if the removed magnetic poles were present, and an element for detecting rotation of the rotor provided in the removed magnetic pole space. .

(Operation) In the stator, some of the multiple magnetic poles are removed, and the coils of each phase are wound around the remaining magnetic poles in the same order as if the removed magnetic poles existed. The motor is driven to rotate by energizing the phase coils in a predetermined order. Since the element for detecting the rotation of the rotor is provided in the removed magnetic pole space, the element faces the outer circumferential surface of the rotor and can reliably detect the rotation signal.

(Example) Hereinafter, an example of a brushless motor according to the present invention will be described with reference to FIGS. 1 to 12.

1 to 5, a mounting plate 32 is fixed to the open end of a cup-shaped case 31, and a shaft 33 is rotatably supported by the case 31 and the mounting plate 32 via bearings 34 and 35. has been done. Shaft 3 protruding from mounting plate 32
A capstan 36 is attached to the end of 3.

A stator core 37 is fixed to the inner peripheral surface of the case 31. As shown in FIG. 1, the stator core 37 has a plurality of magnetic poles 37a protruding inward from a ring-shaped base, and has a shape in which three of the twelve magnetic poles are removed in a predetermined order. is formed. The stator core 37 is
Positioning in the direction of the shaft 33 is achieved by pressing the upper end surface of the ring-shaped base in FIG. 2 with an inward protrusion 31a formed on the case 31 as shown in detail in FIG. There is. In FIG. 1, ■■■ indicate the magnetic poles around which the 1-phase, 2-phase, and 3-phase coils 38 are wound, respectively. Each remaining magnetic pole 37 of the stator core 37
A coil 38 is wound around a, and the order of the phases of each coil 38 is as if the removed magnetic pole were present.

In the magnetic pole space from which the stator core 37 has been removed, a Hall IC 43 as an element for detecting rotation of the rotor is provided via a Hall IC holder 45.

As shown in FIG. 3, the holder 45 has a pair of elastic prongs 45a, 45a, and these prongs 45a
% 45a, and magnetic poles 37a adjacent to both sides of the removed magnetic pole of the stator core 37, and the pronged portion 45a between the magnetic poles 37a.
, 45a, and thereby the Hall IC 43 is positioned and attached.

A rotor magnet 40 is integrally attached to the shaft 33. The rotor magnet 40 is formed by integrally molding a driving magnet and a tachogenerator magnet using, for example, a plastic magnet, and the outer peripheral surface of the rotor magnet portion faces each magnetic pole 37a of the stator core 37 and each Hall IC 43.

A circuit board 42 is fixed inside the mounting plate 42. A coil for the frequency generator is printed on the circuit board 42, and the magnet for the tachogenerator is also printed on the circuit board 42 facing the coil portion for the frequency generator of the circuit board 42. The hall IC4
A lead wire 44 to the outside from the circuit board 42 to which the lead wire 43a of No. 3 is connected is drawn out through a hole formed in the circuit board 42 and the mounting plate 32.

Such a brushless motor is assembled in the following order. First, the circuit board 42 is adhered to the mounting plate 32. At this time, in order to position the circuit board 42 with respect to the mounting plate 32, the center hole B and the eccentric hole A (see FIG. 5)
Use. Next, in order to position the Hall IC holder 45, holes C1 and C2, C3 and C4, and C
Fit the legs of each holder 45 into 5 and 06. The Hall IC 43 is fitted into each holder 45 and positioned. The lead wire 43a of each Hall IC 43 is soldered to a predetermined position on the circuit board 42 to connect the Hall IC 43 to the circuit board 42. The leads of each stator coil 38 are soldered to the circuit board 42.

Next, the stator core 37 is attached to the Hall IC holder 45. Core 37 is positioned by holder 45. Adjust the slack in each lead wire so that it does not come into contact with the rotor, etc. Next, after inserting the rotor, cover the case 31 and attach the case 31 to the mounting plate 3 with screws.
2 to complete the assembly.

According to the brushless motor according to the above embodiment, some of the magnetic poles of the stake core are removed, a Hall IC is provided in the removed magnetic pole space, and the Hall IC is arranged to face the outer peripheral surface of the rotor magnet. Therefore, Hall I
Since the output waveform of C is good and efficiency is high, and there is no magnetic flux leaking from the stator, the Hall IC will not malfunction.

In addition, the Hall IC is positioned with a Hall IC holder,
Since the stator core is positioned using the Hall IC holder, there is no need to adjust the gap between the Hall TC and the rotor magnet, or the gap between the tachogenerator magnet and the circuit board. After fixing it to the IC holder and correcting the slack in the lead wires, you can cover it with a case.

In addition, the space in which the magnetic poles of the stator core are removed has sufficient space even if a Hall IC is installed there, so it is possible to pass the screws for fixing the case and the mounting plate through this free space. Unlike the case where the case and the mounting plate are fixed together, there is no need to create an extra escape space when mounting the motor to various devices.

Furthermore, an inwardly protruding portion 3 formed on the side of the case
1a and the Hall IC holder 45, the stator core 3
7 is sandwiched in the thrust direction, and the case and mounting plate are tightened with screws to position and fix the stator core. However, if the Hall IC holder 45 is made of resin, it may deform due to creep or temperature over many years. or loosening may occur. Therefore, a gap is formed in the punched out part 31a formed on the case as shown in FIG. 4, and after the case and the mounting plate are screwed together, adhesive is poured through the gap to firmly secure the case and the stator core. After applying the adhesive, the gap between the punched out parts 31a is closed.

Next, various modifications applicable to the present invention will be described.

FIG. 6 shows another example of the stator core, in which some of the plurality of magnetic poles 50a are removed from the stator core 50, and a recess is formed on the side surface of the magnetic pole 50a adjacent to the removed magnetic pole space. 50b is formed. This recess 50b is for positioning and fixing the Hall IC holder 52, as shown in FIG. 7, and a Hall IC 53 is fixed to the Hall IC holder 52.

As shown by ■■■, the coils of each phase are wound around the remaining magnetic poles 50a of the stator core 50 in the same order as if the removed magnetic poles existed.

FIG. 8 shows still another example of the stator core, in which each corner of the slot between the magnetic poles 54a is formed into a circular arc so that the coil can be easily wound in an aligned manner around each magnetic pole 54a of the stator core 54. It is not formed with a square shape, but is formed into a corner shape with an angle of 90 degrees.

A part of the magnetic pole of the stator core 54 is removed, and a hole I is formed on the side of the magnetic pole 54a adjacent to the removed magnetic pole space.
A recess 54b is formed for positioning and fixing the C holder. Further, the stator core 54 is integrally formed with a screw holding hole 54c for fixing the case and the mounting plate in the removed magnetic pole space. In place of the screw holding hole 54c, a concave screw holding part 54d as shown by reference numeral 54d may be formed.
If 4d is formed to draw an arc of 180° or more, or if it is formed like the above-mentioned holding hole 54c, when the screw that fixes the case and the mounting plate is passed through, this screw will be pulled toward the rotor side by magnetic force. Since it is possible to prevent the case from tilting even when the case is tilted, it becomes easy to fix the case and the mounting plate.

In addition to the embodiments described above, various examples such as those shown in FIGS. 9 to 12 are conceivable as a form in which some of the plurality of magnetic poles of the stator core are removed.

The examples shown in FIGS. 9 and 10 show examples of stator cores 56 and 58 in which three poles have been removed from the 12 magnetic poles in a three-phase configuration. The magnetic poles have been removed to prevent imbalance. Hall ICs 57 and 59 as rotor rotation detection elements are arranged in the removed magnetic pole spaces, respectively.

The example of FIG. 11 shows an example of a stator core 60 in which three bridges are removed from 15 magnetic poles of a three-phase configuration. A Hall IC 61 is disposed in the removed magnetic pole space.

In this case as well, the magnetic poles are removed in such a way that the phase balance of the coils wound in the remaining magnetic pole spaces is not disrupted.

In addition, the present invention can also be applied to a motor with a stator core that has nine magnetic poles in a three-phase configuration, and some of the nine magnetic poles are removed (the form is such that the balance between each phase of the coil is not disturbed). You may set it as appropriate within the range.

The present invention can also be applied to a four-phase motor. FIG. 12 schematically shows an example of a stator core in that case, in which the dashed lines represent the removed magnetic poles, and the solid lines represent the remaining magnetic poles. ■■■■ indicate the magnetic poles around which the 1-phase, 2-phase, 3-phase, and 4-phase coils are to be wound, respectively.The element that detects the rotation of the rotor is located in one of the removed magnetic pole spaces. It is sufficient to place it in

If there is no tachogenerator or if the tachogenerator board is separated from the Hall IC board, a recess for positioning the holder should be provided in the stator core as shown in the example in Fig. 6, or an insulating member between the stator core and the coil should be provided. cover the stator core, provide a recess as shown in Figure 6 in the insulating member, fit a holder into this recess, position and fix the Hall IC to this holder, and then solder the lead wire of the Hall IC to the board. (See FIG. 7), or a method such as positioning the board on the holder and positioning the Hall IC on the board can be considered.

The holder for attaching the rotation detection element is not essential to the present invention, and can be omitted. To determine the relative positioning of the stator core and rotation detection element when a holder is not used, for example, first fix the circuit board with the rotation detection element to the case using the screw holes as a reference, and then This can be done by aligning the case with reference to the screw holding parts of the stator core with screw holding parts as shown by 54c and 54d.

(Effects of the Invention) According to the present invention, some of the plurality of magnetic poles of the stator core are removed and an element for detecting the rotation of the rotor is placed in the removed magnetic pole space. It is now possible to arrange the rotor so that it faces the outer circumferential surface of the rotor, making it possible to reliably obtain rotor commutation signals.

In addition, since the space for installing the Hall IC can be easily secured,
It is possible to make the motor thinner without degrading its performance, and moreover, it is possible to reduce the weight by removing some of the magnetic poles.

[Brief explanation of drawings]

FIG. 1 is a plan view showing essential parts of an embodiment of a brushless motor according to the present invention, FIG. 2 is a longitudinal sectional view of the same embodiment, and FIG.
The figure is a front view of the rotation detecting element in the above embodiment.
The figure is a cross-sectional view showing a part of the case in the above embodiment.
The figure is a plan view of the circuit board in the above embodiment, FIG. 6 is a plan view showing another example of the stator core that can be used in the present invention, and FIG. A front view showing an example, FIG. 8 a plan view showing still another example of a stator core that can be used in the present invention, and FIGS. 9 to 11 showing various examples of stator cores that can be used in the present invention. A plan view, FIG. 12 is a plan view schematically showing another example of a stator core that can be used in the present invention, and FIG. 13 is a partially cutaway plan view showing an example of a conventionally considered brushless motor. 14th
The figure is a vertical cross-sectional view of the same brushless motor, FIG. 15 is a vertical cross-sectional view showing a part of the case of the brushless motor, and FIG.
FIG. 6 is a longitudinal cross-sectional view showing another example of a conventionally considered brushless motor. 37... Stake core, 37a... Magnetic pole, 3
8... Coil, 43... Hall IC 150, 54, 56, 58, 60... Stator core, 50a, 54a...-Magnetic pole, 53.
57.59.61...Hall I as rotation detection element
C. La V mouth f phantom

Claims (1)

[Claims] A stator in which some of the plurality of magnetic poles are removed and coils of each phase are wound around the remaining magnetic poles in the order as if the removed magnetic poles existed, and the removed magnetic poles. A brushless motor comprising: an element that detects rotation of a rotor provided in a space.