JPH0744816B2 - Brushless motor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor, and more particularly to an arrangement structure of elements for detecting rotation of a rotor of a brushless motor.

(Prior Art) A DC brushless motor is used as a spindle driving motor of a backup storage device such as a computer.
The DC brushless motor for such applications is required to rotate at high speed, and to start and stop repeatedly, immediate startability and immediate stopability are required. There is also a demand for thinner motors due to thinner memory devices, and low inertia inner rotor type flat DC brushless motors are being studied. Further, the spindle drive motor of the storage device is required to have, for example, a tacho generator of several pulses per rotation in order to control the rotation speed.

In order to meet these requirements, 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 brush motor shown in FIGS. 13 to 15 will be described. In this motor, the stator has 12 slots and the rotor has 8 magnetic poles. 13 to 15, a mounting plate 12 is fixed to the open end of a cup-shaped case 11, and the shaft 11 is rotatably held by the case 11 and the mounting plate 12 via bearings 14 and 15. Has been done. A capstan 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 magnetic pole 17a. A magnet holder 19 having a rotor magnet 20 fixed to the outer periphery is fixed to the shaft 13, and the rotor magnet 20 can freely rotate together with the holder 19 on the inner peripheral side of the stator core 17. A circuit board 22 to which a Hall IC 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 tachogenerator magnet 21 is fixed to the lower end surface of the magnet holder 19, and the magnet 21 faces a power generation coil pattern printed on the circuit board 22. A part of the circuit board 22 projects outward from the hole 11a formed in the case 11, and the lead wire 24 is connected to the projecting portion of the circuit board 22.

The brushless motor has the following problems.

(1) Since the driving magnet and the tacho-generator magnet are separately provided and are integrally assembled, the rotor becomes expensive.

(2) The magnetic flux generated from the end face of the driving magnet is small,
Since the Hall IC is operated by picking up this small magnetic flux, the output waveform of the Hall IC is poorly cut and the efficiency is poor.

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

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

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

(6) Although it is necessary to form a long hole serving as an outlet of the circuit board on the side portion of the case, the circuit board needs to be adhered to the inner bottom portion of the case because it is fixed by adhesion.
The long hole of the case needs to be formed so that there is no protrusion from the bottom surface of the case, which is troublesome to process (see Fig. 15).

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

(8) The case and the mounting plate are of the caulking type, and when mounting the motor to various devices, it is necessary to allow the protruding portion of the caulking portion to escape, which requires a lot of mounting space.

A brushless motor as shown in FIG. 16 has been proposed in order to eliminate many of these problems. The first difference between the brushless motor of FIG. 16 and the brushless motor is that the drive magnet and the tachogenerator magnet are integrally molded with a plastic magnet, and this is used as the rotor magnet 25. As a result, the above-mentioned problem (1) is solved. Further, in order to solve the problems (6) and (7), the circuit board 26 is fixed to the mounting plate 12 side, and the lead wire is soldered inside the motor through the circuit board 26 and the mounting plate 12. Therefore, the hole for the lead wire can be formed by pressing, the circuit board can be made small, and the fixing of the lead wire can be processed inside the motor, so that the mounting space of the motor can be made smaller. You can

(Problems to be Solved by the Invention) However, even in the brushless motor shown in FIG. 16, the problems (2) to (5) have not been solved yet. Moreover, with the brushless motor of FIG. 16, it is more difficult to eliminate the above-mentioned drawback (5). That is, after fixing the stator core to the case,
To fit the mounting plate with the circuit board to the case,
This is because the positional relationship between the Hall IC and the stator core is decided when the stator core is fixed to the case.

Also, the lead wire of the stator coil is soldered to the circuit board before fitting the mounting plate to the case, so when the mounting plate is fitted to the case, the lead wire sags and the lead wire touches the rotor. 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, so that the rotation sensing element can be arranged to face the outer peripheral surface of the rotor so that the commutation signal of the rotor can be reliably obtained. It is another object of the present invention to provide a brushless motor that can be thinned and lightened so that a mounting space for a Hall IC can be easily obtained.

(Means for Solving Problems) In the brushless motor according to the present invention, a part of a plurality of magnetic poles having the same shape is removed, and the remaining magnetic poles are
A magnetic field having a removed magnetic pole, and a stator in which coils of each phase are wound in such an order as if the magnetic pole were removed; and an element for detecting rotation of a rotor provided in the removed magnetic pole space. To do.

(Operation) In the stator, a part of a plurality of magnetic poles having the same shape is removed, and the remaining magnetic poles are wound with coils of each phase in such an order that the removed magnetic poles exist. Therefore, the motor is rotationally driven by energizing the coils of each phase in a predetermined order. Since the element that detects the rotation of the rotor is provided in the removed magnetic pole space, the element faces the outer peripheral surface of the rotor, and the rotation signal can be reliably detected.

(Embodiment) An embodiment of the brushless motor according to the present invention will be described below with reference to FIGS. 1 to 12.

1 to 5, a mounting plate 32 is fixed to an open end of a cup-shaped case 31, and the case 31 and the mounting plate are attached to each other.
A shaft 33 is rotatably supported by bearings 34 and 35 by 32 and. A capstan 36 is attached to the end of the shaft 33 protruding from the mounting plate 32. A stator core 37 is fixed to the inner peripheral surface side of the case 31. Stator core 37
As shown in FIG. 1, a plurality of magnetic poles 37a of the same shape are projected inward from the ring-shaped base,
Three poles of the poles are removed in a predetermined order. In the stator core 37, the upper end surface of the ring-shaped base portion in FIG. 2 is pressed by an inward punching portion 31a formed in the case 31 as shown in detail in FIG. The positioning is done.
FIG. 1 shows magnetic poles around which one-phase, two-phase and three-phase coils 38 should be wound. Stator core
The coils 38 are wound around the remaining magnetic poles 37a of the coil 37, but the order of the phases of the coils 38 is such that the removed magnetic poles exist.

In the removed magnetic pole space of the stator core 37, a Hall IC 43 as an element for detecting the rotation of the rotor is provided via a Hall IC holder 45. The holder 45, as shown in FIG. 3, has a pair of elastic fork portions 45a, 45a,
The Hall IC 43 is positioned and held between the forked portions 45a, 45a, and the outer surface of the forked portions 45a, 45a is inserted between the magnetic poles 37a, 37a adjacent to both sides of the removed magnetic pole of the stator core 37. 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 tacho-generator magnet with a plastic magnet, for example, and the outer peripheral surface of the rotor magnet portion has magnetic poles 37a of the stator core 37 and Hall ICs 43.
Is facing.

A circuit board 42 is fixed inside the mounting plate 32.
A coil for a frequency generator is printed on the circuit board 42, and the magnet for the tachogenerator faces the coil portion for the frequency generator of the circuit board 42. The circuit board 42 also has lead wires 43 of the Hall IC 43.
a is connected. Lead wire 4 from circuit board 42 to the outside
4 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 bonded to the mounting plate 32.
At this time, the center hole B and the eccentric hole A (see FIG. 5) are used to position the circuit board 42 with respect to the mounting plate 32. Next, in order to position the Hall IC holder 45, the legs of each holder 45 are fitted into the holes C1 and C2, C3 and C4, C5 and C6 of the circuit board 42. The Hall IC 43 is fitted to 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 attach the Hall IC 43 to the circuit board 42.
Connect to. The lead wire of each coil 38 of the stator is soldered to the circuit board 42. Next, attach the stator core 37 to the Hall IC.
Attach according to holder 45. The core 37 is positioned by the holder 45. Re-slacken the lead wires so that each lead wire does not come into contact with the rotor. Next, after inserting the rotor, the case 31 is covered, and the case 31 is fixed to the mounting plate 32 by screwing to complete the assembly.

According to the brushless motor according to the above-described embodiment, a part of the plurality of magnetic poles of the stator core is removed, and the 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. , Hall IC output waveform is good and efficient, and there is no leakage flux from the stator, so Hall IC does not malfunction.

Further, since the Hall IC is positioned by the Hall IC holder and the stator core is positioned by the Hall IC holder, it is not necessary to adjust the gap between the Hall IC and the rotor magnet and the gap between the tacho generator magnet and the circuit board, and Without fixing the stator core to the case, it is possible to fix the stator core to the Hall IC holder, fix the slack of the lead wire, and then cover the case.

Also, since the space for removing the magnetic poles of the stator core has a spatial margin even if the Hall IC is mounted here, it is possible to pass a screw for fixing the case and the mounting plate into this extra space, Therefore, unlike the case where the case and the mounting plate are fixed to each other, it is not necessary to form an extra escape space when the motor is attached to various devices.

In addition, the inwardly projecting portion 31 formed on the side surface of the case
The stator core 37 is sandwiched in the thrust direction by a and the Hall IC holder 45, and the stator core is positioned and fixed by tightening the case and the mounting plate with screws.However, when the Hall IC holder 45 is made of resin, , Deformation or loosening may occur due to long-term creep or temperature. Therefore, a gap is formed in the punched-out portion 31a formed in the case as shown in FIG. 4, and after the case and the mounting plate are screwed, the adhesive is poured into the case to firmly fix the case and the stator core. It is desirable to fix it to. After the adhesive is applied, the punched-out portion 31a
Close the gap.

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

FIG. 6 shows another example of the stator core. In the stator core 50, a part of the plurality of magnetic poles 50a having the same shape is removed, and the magnetic pole 50a adjacent to the removed magnetic pole space is shown. A recess 50b is formed on the side surface. The recess 50b is used for positioning and fixing the Hall IC holder 52 as shown in FIG.
The Hall IC 53 is fixed to the holder 52. The remaining magnetic poles 50a of the stator core 50 are wound with coils of respective phases in the order as if the removed magnetic poles exist, as indicated by.

FIG. 8 shows still another example of the stator core. Each corner of the slot between the magnetic pole 54a and the magnetic pole 54a has an arc so that the coil can be easily wound around each magnetic pole 54a of the stator core 54 in an aligned winding. It is not formed by, but is formed into a square shape at an angle of 90 degrees. A part of the magnetic poles of the stator core 54 is removed, and a recess 54b for positioning and fixing the Hall IC holder is provided on the side surface of the magnetic pole 54a adjacent to the removed magnetic pole space.
Are formed. 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. Instead of the screw holding hole 54c, a concave screw holding portion as shown by reference numeral 54d may be formed. Screw holder 54d
Is formed so as to draw an arc of 180 ° or more, or is formed like the holding hole 54c, when a screw for fixing the case and the mounting plate is passed, this screw is pulled by the magnetic force to the rotor side. Since it can be prevented from tilting, the case and the mounting plate can be easily fixed to each other.

As a form in which some of the plurality of magnetic poles of the stator core are removed, in addition to the embodiment described above, various examples as shown in FIGS. 9 to 12 can be considered.

The example shown in FIG. 9 and FIG.
Shows an example of the stator core 56, 58 with poles removed,
In each case, the magnetic poles are removed so that the phase balance of the coil wound around the remaining magnetic poles is not lost. In the removed magnetic pole space, Hall IC5 as a rotor rotation detection element
7 and 59 are arranged respectively.

The example of FIG. 11 shows an example of the stator core 60 in which three poles are removed from the 15-pole magnetic pole having a three-phase structure. The Hall IC 61 is arranged in the removed magnetic pole space. Also in this case, the magnetic poles are removed so that the phase balance of the coils wound in the remaining magnetic pole space is not disturbed.

In addition, the present invention is also applicable to a motor with a stator core having 9-pole magnetic poles of a 3-phase structure, and a mode in which a part of the 9-pole magnetic poles is removed is a range in which the balance between the phases of the coil is not lost. May be set appropriately.

The present invention is also applicable to a 4-phase motor. FIG. 12 schematically shows an example of the stator core in that case,
Among the plurality of magnetic poles, the magnetic pole from which the chain line is removed and the solid line are the remaining magnetic poles. Are one phase, two phases, three phases,
4 shows a magnetic pole around which a 4-phase coil is to be wound. The element for detecting the rotation of the rotor may be arranged in one of the removed magnetic pole spaces.

When a substrate without a tachogenerator or a substrate for a tachogenerator and a substrate for a Hall IC are separated, a recess for positioning the holder is provided in the stator core as in the example of FIG. 6, or an insulating member between the stator core and the coil. Over the stator core, provide the insulating member with a recess as shown in FIG. 6, fit a holder into this recess, position and fix the Hall IC in this holder, and then solder the lead wire of the Hall IC to the board. (See FIG. 7), or a method of positioning the substrate on the holder and positioning the Hall IC on the substrate can be considered.

The holder for mounting the rotation detecting element is not essential to the present invention, and the holder can be omitted. Relative positioning of the stator core and the rotation detecting element when the holder is not used is performed, for example, by first fixing the circuit board with the rotation detecting element to the case with reference to the screw holes, and then referring to FIG. This can be done by aligning the case with reference to the screw holding portion of the stator core with screw holding portions as shown by 54c and 54d.

(Effect of the Invention) According to the present invention, a part of the plurality of magnetic poles having the same shape of the stator core is removed, and the element for detecting the rotation of the rotor is arranged in the removed magnetic pole space. , The element can be arranged so as to face the outer peripheral surface of the rotor, and the commutation signal of the rotor can be reliably obtained. Further, since the space for arranging the Hall IC can be easily secured, it is possible to make the motor thinner without degrading the performance of the motor, and moreover,
Weight can be reduced by removing some magnetic poles.

[Brief description of drawings]

FIG. 1 is a plan view showing a main part of an embodiment of a brushless motor according to the present invention, and FIG. 2 is a longitudinal sectional view of the same embodiment as above.
FIG. 4 is a front view of a portion of the rotation detecting element in the above embodiment, FIG.
FIG. 5 is a cross sectional view showing a part of the case in the above embodiment,
FIG. 6 is a plan view of the circuit board in the above embodiment, FIG. 6 is a plan view showing another example of a stator core that can be used in the present invention, and FIG. 7 is a mounting structure of a rotation detecting element used together with the stator core. Examples are front views, FIG. 8 is a plan view showing still another example of the stator core that can be used in the present invention, and FIGS. 9 to 11 show various examples of the stator core that can be used in the present invention. Plan view, FIG. 12 is a plan view schematically showing still another example of a stator core that can be used in the present invention, FIG. 13 is a partially broken plan view showing an example of a conventionally considered brushless motor, FIG. 14 is a vertical cross-sectional view of the same brushless motor, FIG. 15 is a vertical cross-sectional view showing a part of the brushless motor case, and FIG. 16 is a vertical cross-sectional view showing another example of a conventionally considered brushless motor. Is. 37 …… stator core, 37a …… magnetic pole, 38 …… coil, 43
... Hall ICs as rotation detection elements, 50, 54, 56, 58,
60 ... Stator core, 50a, 54a ... Magnetic pole, 53, 57, 59,
61 …… Hall IC as a rotation detection element.

Claims (1)

[Claims] 1. A part of a plurality of magnetic poles having the same shape is removed, and a coil of each phase is wound on the remaining magnetic poles in such an order that the removed magnetic poles exist. A brushless motor comprising: a stator; and an element for detecting rotation of a rotor provided in the removed magnetic pole space.