JPH03261358A - Dc brushless motor - Google Patents

Abstract

PURPOSE:To reduce magnetic reluctance and gain large output torque by forming an armature which consists of an armature section and a coil and is sandwiched between a pair of permanent magnets. CONSTITUTION:A recessed section 11b extended in the radial direction along the outer surface of a ring shaped rotor 11 mounted on a rotating shaft, is formed and permanent magnet bodies 12 and 13 are mounted on walls facing the recessed section 11b. The permanent magnet bodies 12 and 13 have permanent magnets magnetized in the axial direction, which are positioned in a ring shape so that their polarity changes alternately. Since an armature is sandwiched between the permanent magnet bodies 12 and 13, reluctance of a magnetic circuit can be minimized and the density of magnetic fluxes increases, a large torque can be gained.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a DC brushless motor.

(Prior Art) Conventionally, so-called print motors and coreless motors (cup-shaped print motors) are known as motors that output high torque while reducing ripple at low torque.

In these print motors, the armature coil is formed into a disk shape (or cup shape) and is immersed in resin to be resin molded. This eliminates the iron core and eliminates cogging torque (pulsation) due to the shape of the iron core (generally, such cogging torque is caused by coil slots formed in the armature core).

(Problems to be Solved by the Invention) By the way, in the above-mentioned printed motor and coreless motor, since the armature coil is of a so-called moving coil type that rotates, a brush is inevitably required, and the motor is maintenance-free, explosion-proof, and There are also problems in terms of dustproofing.

Furthermore, in recent years, high-performance magnets such as rare earth magnets have been realized, and as a result, extremely high magnetic flux densities can be obtained.

However, in the above-mentioned printed motor and coreless morph, since the armature coil is molded with resin, the shape of the armature coil cannot be made with high accuracy, and therefore the distance (gap) between the armature coil and the stator is Difficult to make small. In other words, even if rare earth magnets are used, the magnetic flux cannot be used effectively and there is a problem that there is a lot of loss.

SUMMARY OF THE INVENTION An object of the present invention is to provide a DC brushless motor that has few ripples at low torque and can effectively utilize magnetic flux to obtain a large torque output.

(Means for Solving the Problems) According to the present invention, a DC brushless DC brushless motor has a ring-shaped rotor attached to a rotating shaft, and a stator arranged to face the rotor and surround the outer peripheral surface of the rotor. In the motor, the rotor has four parts extending in the radial direction formed along the outer periphery of the rotor, and the mutually opposing wall surfaces of the recessed parts are magnetized in the axial direction and have magnetic poles that alternately change at predetermined intervals. A permanent magnet is attached to the stator, an armature portion extending into the recess is formed in the stator, a coil is wound around the armature portion, and a rotational position detection sensor is provided for detecting the rotational position of the rotor. A DC brushless motor is obtained.

(Function) In the present invention, since the armature constituted by the armature portion and the coil is sandwiched between a pair of permanent magnets, the magnetic resistance of the magnetic flux path can be reduced and the magnetic flux density can be increased. As a result, a large torque output can be obtained. Furthermore, since no coil slot is formed in the armature portion, cogging torque can be reduced.

(Example) The present invention will be explained below with reference to Examples.

Referring to FIG. 1, a ring-shaped rotor 11 is attached to a rotating shaft (not shown) with a rotor fastening bolt lla. A recess 11b is formed along the outer peripheral surface of the rotor 11 and extends in the radial direction, and permanent magnet bodies 12 and 13 are attached to opposing wall surfaces of the four parts 11b, respectively.

Here, referring also to FIG. 2, the permanent magnet bodies 12 and 13 have a plurality of permanent magnets 14 magnetized in the axial direction,
These permanent magnets 14 are arranged in a ring shape as shown in FIG. Furthermore, these permanent magnets 14 are arranged so that their magnetic poles change alternately (that is, the permanent magnets 12 and 13 have N poles and S poles arranged alternately).

Referring again to FIG. 1, bearings 15 and 16 are attached to the outer peripheral end of the rotor 11.
An annular stator 17 connects to the rotor 11 via 5 and 16.
is connected to. An armature portion (iron core portion) 17a extending in the radial direction is formed in the stator 17, and this iron core portion 17a extends into the recessed portion 11b of the rotor 11. A three-phase armature coil 17b is wound around this iron core portion 17a, and this armature coil 17b is connected to a power supply receptacle 17c. The arrangement pitch of the permanent magnets 14 and the winding pitch of the armature coil 17b are determined so that the arrangement pitch of the permanent magnets 14 and the winding pitch of the armature coil 17b have a predetermined phase difference.

Here, referring also to FIG. 3, assuming that the direction of magnetic flux by the permanent magnet 14 is the direction shown by numbers 18a and 18b, the armature coil 17b is wound around the iron core 17a as shown in FIG. It is passed around. As a result, the magnetic flux passing through the iron core portion 17a is perpendicular to the armature coil 17b.

As shown in FIG. 1, a magnetic sensor (for example, a resolver) 19 is arranged near the permanent magnet 12, and this magnetic sensor 19 detects the permanent magnet 12 (and the permanent magnet 12).
3) Know the rotational position.

The output end of the magnetic sensor is connected to a power supply control device (not shown) as is well known, and is connected to the armature coil 17b via the power receptacle 17c in accordance with the rotational position of the permanent magnet body 12 detected by the magnetic sensor 19. Controls the phase of the supplied current.

As mentioned above, in the present invention, since the armature composed of the iron core and the armature coil is sandwiched between a pair of permanent magnets,
The magnetic resistance of the magnetic flux path can be reduced, and as a result, the magnetic flux density can be substantially increased. Furthermore, since the armature is sandwiched between a pair of permanent magnets, the magnetic attraction force can be balanced and deviation of the armature can be prevented. Furthermore, the magnetic energy can be substantially increased without increasing the size of the magnet.

Note that since the magnetic flux passing through the iron core and the armature coil are perpendicular to each other, the effective output torque becomes large.

(Effects of the Invention) As explained above, in the present invention, since the armature consisting of the armature portion and the coil is sandwiched between a pair of permanent magnets, the magnetic resistance of the magnetic flux path can be reduced, and the magnetic flux density can be increased. I can do it. As a result, a large torque output can be obtained. Furthermore, since no coil slot is formed in the armature section, there is an effect that cogging torque can be reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the DC brushless motor according to the present invention, FIG. 2 is a plan view showing a permanent magnet body used in the DC brushless motor shown in FIG. 1, and FIG. 3 is a diagram showing magnetic flux and armature. It is a figure showing the relationship with a coil. 11...Rotor, 12.13...Permanent magnet, 14
...Permanent magnet, 15.16...Bearing, 17.
...Stator, 19...Magnetic sensor Figure 2 Section 3

Claims (1)

[Claims] 1. A DC brushless motor having a ring-shaped rotor attached to a rotating shaft and a stator disposed opposite to the rotor so as to surround the outer peripheral surface of the rotor, wherein the rotor has a recess extending in the radial direction. Permanent magnets are formed along the outer circumference of the rotor, and are magnetized in the axial direction and whose magnetic poles alternately change at predetermined intervals, respectively, are attached to the mutually opposing wall surfaces of the recesses, and the stator is attached to the recesses. An armature portion extending inward is formed;
A DC brushless motor, characterized in that a coil is wound around the armature portion, and a rotational position detection sensor is provided for detecting the rotational position of the rotor.