JPS60183958A - Dc brushless motor - Google Patents

Abstract

PURPOSE:To reliably start by constructing the opening shape of a stator core in which a rotor is mounted in combination of the same radius and circular arcs of different central points. CONSTITUTION:A stator winding 1 is wound on a bobbin 3 having a core 2. The shape of the hole of a stator core 4 is constructed in combination of the same radius (l) and circular arcs 5, 6 of different central points O1, O2. The core 4 is formed in a skeleton shape, thereby generating a magnetic bridge portion 7. A discontinuous point C-C' of an air gap is formed at the rightside pole exceeding the bridge portion 7.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to a skeleton-type small electric motor or a small electric motor using a C-type stator core, and particularly relates to a small-sized electric motor using a skeleton type stator core. It's about shape.

(b) Prior art In general, the shape of the opening in the core of a small electric motor having a stator core and stator windings, that is, the air gap between it and the rotor, is, for example, The skeleton type small electric motor described in Japanese Utility Model Publication No. 57-8368 had a uniform air gap. For this reason, the rotor's stopping position when power to the stator windings was stopped was affected by factors such as the rotational inertia of the connected load and the alignment of the bearing parts, and the rotor did not stop at a fixed position. . The stopping position of the rotor is not a problem in the case of a shaded motor, but if a permanent magnet is used in the rotor to create a DC brushless system, the position of the rotor becomes a problem when starting the motor. Become. That is, it was necessary to switch the energization to the stator windings in accordance with the stopped position of the rotor. Therefore, a Hall element was provided to detect the position of the rotor. However, when the number of poles of the stator and the number of poles of the rotor are two, if the rotor is stopped at a position where the centers of both poles coincide, startup is impossible. In this case, the number of Hall elements installed, the number of poles of the stator, and the number of poles of the rotor are varied in a specific relationship. For example, if the stator has three poles and the rotor has four poles, this problem can be solved, but as the number of Hall elements increases, the current control circuit for the stator windings becomes more complex and larger, making it difficult to operate the motor. The structure is complicated and expensive, and at the same time reliability is reduced in terms of maintenance and inspection.

Therefore, it is generally known that the rotor needs only to be stopped at a constant position, and that the air gap between the rotor and the stator core can be changed for this purpose. This air gap was partially set by partially widening the air gear, but depending on the rotational inertia of the rotor, it was sometimes impossible to stop at a fixed position.

. Furthermore, in the electric motor described in Japanese Patent Application Laid-open No. 57-83149, the air gap between the rotor and stator core is changed by changing the openings in the cylindrical stator core, so that the rotor is always It was made to stop at a certain position. However, in such a motor, the stator winding is directly wound around the stator core with a uniform thickness, and at the same time, the direction of the magnetomotive force generated in the stator winding is positioned at 90° with respect to the direction of the rotor's magnetic field. It was necessary to install the stator winding in an accurate position so that Furthermore, the air gap may become wider than necessary due to the stator winding.

This causes leakage of magnetic flux, which is disadvantageous to the operating characteristics of the motor, and requires a permanent magnet with a high residual magnetic flux density and a permanent magnet with a coercive force that is resistant to irreversible demagnetization, resulting in an increase in cost. In addition, the minimum air gap cannot be made too small as it is affected by the thickness of the stator windings, so the restoring force required to stop at a certain position cannot be reduced, and the usable load range is also narrowed. .

(c) Purpose of the Invention In view of the above-mentioned problems, the present invention provides a DC brushless motor using a skeleton type or C-type stator core that can be started reliably.

(B) Structure of the Invention The present invention provides that the shape of the opening in the stator core of a DC brushless motor having a skeleton type stator core and a stator winding or a C-type stator core and a stator winding has the same radius. The rotor is constructed of a combination of circular arcs that are large and have different center points, so that the rotor always stops at a fixed position.

(E) Embodiments Below, embodiments of the present invention will be explained based on FIGS. 1 and 2. (1) is a stator winding, which is wound around a bobbin (3) having an iron core (2). ing. (4) is the stator core, and the shape of the opening is the same radius (11) and the center point (01
), (02) are composed of a combination of different arcs (5) and (6). Moreover, by making the shape of the stator core (4) into a skeleton shape as shown in FIG. 1, a magnetic bridge portion (7) is created. Also, C-C is the discontinuous change point of the air gear knob, and the right pole (
clockwise). X-X is the center line of the rotor and stator, and when the stator winding (1) is de-energized, the rotor (8) balances the attraction force due to changes in the air gap of the stator core (4). This is the position where it comes to rest. Since the electric motor of the present invention does not provide a stator winding within the air gap, the minimum air gap can be reduced and the restoring force to the resting position can be increased.

Y-Y is the center of the magnetic field generated when the stator winding (1) is energized. In other words, the magnetic flux generated when the stator winding (1) is energized is saturated at the magnetic bridge section (7), and
7) The magnetic poles separate at the border. In addition, the rotor (8
) has a permanent magnet with S and N poles and rotates around a rotating shaft (9). 00) is a Hall element or Hall I
It is a position detector consisting of C, etc., and this position detector 0ω
The direction of current supply to the stator winding (1) is switched based on the output of the stator winding (1).

In the DC brushless motor configured as described above, when the stator winding (1) is not energized, the rotor (8) always rotates at a constant speed as shown in Figure 1 due to the balance of magnetic attraction force. It is stopped at a position rotated by 180 degrees from the position shown in FIG. For example, when the rotor (8) is stopped in the state shown in Figure 1, if current is applied from terminal P to terminal N of the stator winding (11), it will be fixed across the magnetic bridge (7). The Y side of the child core (4) becomes the N pole and the Y side becomes the S pole.At this time, the magnetomotive force direction Y-Y of the stator winding (1) and the magnetic field direction X-X of the rotor (8) are approximately 90 degrees Since the angle is in degrees, a large starting torque is generated and the rotor (8) rotates clockwise (
clockwise). After this, the rotor (8) rotates 180 degrees and the magnetic pole of the rotor (8) detected by the position detector QOI is reversed, and the direction of current flow to the stator winding (1) is changed from terminal N to
Switch between terminals P and \. As a result, the Y of the stator core (4)
The side becomes the S pole and the Y side becomes the N pole. Therefore, the rotor (8) maintains its right rotation. Thereafter, the A and li directions to the stator winding (1) are switched according to the rotational position of the rotor, and continuous rotation is maintained by combining the attraction and repulsion of the magnetic field with the rotational inertia of the rotor (8). It is something that will be done.

Note that the stator winding (
As the control circuit for switching the energization direction in 1), a generally known control circuit can be used, so a description thereof will be omitted.

Moreover, FIG. 2 is a front view when a C-type stator core is used, and (7) in the figure is a gap for pole separation.

Hereinafter, the same component costs as those in FIG. 1 will be given the same numbers and the explanation will be omitted.

(F) Effects of the Invention As described above, the present invention provides the shape of the opening in the stator core of a DC brushless motor having a skeleton type stator core and stator winding or a C-type stator core and stator winding. Since the rotor is constructed of a combination of circular arcs with the same radius and different center points, the rotor can always be stopped at a predetermined rotational position and stable startup can be performed. In addition, the shape of the mold for the stator core can be made of a combination of the same circular arcs, making it easy to manufacture the mold and at the same time improving the mold precision.

Furthermore, since a skeleton type or C-type core is used, a magnetic bridge can be easily created on the stator core, and the separation rate of the magnetic poles generated when the stator windings are energized can be increased. In other words, highly efficient operation with suppressed magnetic flux leakage is achieved.1 Since magnetic flux is generally saturated in such a magnetic bridge section, the rotor position detector is connected to the stator core magnetic bridge. The position of the rotor can also be detected even if it is provided on the outer periphery of the contact portion. That is, there are no foreign substances between the rotor and the stator core, which improves the accuracy of the air gap and allows stable startup and operation.

[Brief explanation of the drawing]

FIG. 1 is a front view of an embodiment of the present invention applied to a skeleton type brushless motor, and FIG. 2 is a front view of the case using a C-type stator core. (1)...Stator winding, (4)...Stator core,
(5), (6)...Circular arc, (Ql), (Q2)...
·Center point. Applicant Sanyo Electric Co., Ltd. and 1 other agent Patent attorney Shizuo Sano 44%; 1 Figure P N

Claims (1)

[Claims] (11) In a DC brushless motor with a skeleton type stator core and stator windings, or in a DC brushless motor with a C-type stator core and stator windings, the shape of the openings in the stator core to which the rotor is attached. A DC brushless electric motor characterized by being constructed by a combination of circular arcs with the same radius but different center points.