JPH03128653A - Brushless motor - Google Patents

Abstract

PURPOSE:To eliminate cogging and to reduce uneven rotation by arranging a single, uniformly wound coreless coil and by rotating a rotor made of permanent magnet according to the change of electric current flowing through the coil. CONSTITUTION:A magnetic flux by the permanent magnet of a rotor 1 passes through a magnetic circuit formed by a yoke 7 and crosses a coreless coil 9 existing between the rotor and yoke. Electric current flowing through the coreless coil 9 suitably changes its direction according to the position of the magnetic poles of the rotor 1 to form a rotating magnetic field and rotates the rotor 1 and a shaft 2 so that a torque is outputted. Because the yoke 6 is formed into an integral body over its whole periphery and the coreless coil 9 has no core, a magnetic resistance is prevented from changing according to the angle of rotation so that no cogging occurs consequently. Also, because the coreless coil 9 is uniformly wound continuously round only one spool 10, uneven rotation occurs scarcely.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an inner rotor type brushless motor,
More specifically, the present invention relates to a brushless motor with no cogging and less uneven rotation.

(Conventional technology) The biggest drawback of DC motors is the presence of brushes.

Brushless motors were developed to eliminate the need for brushes. A brushless motor has a winding on the stator side, and has a structure in which the current to the winding is driven and controlled by a semiconductor, and the rotor is made of permanent magnets and is located outside the stator. The one on the inside is called the outer rotor type, and the one on the inside is called the inner rotor type.

By the way, the inner rotor type brushless motor is
The structure is as shown in the figure. In the figure, 1 is a rotor made of permanent magnets, and 2 is a shaft for outputting rotational force by the rotor 1. 3 has slot 4;
A core around which a coil 5 is wound through a slot 4; 6 is a yoke for forming a magnetic path for the rotor 1, which is a permanent magnet; A stator 7 is constituted by the coil 5 and the yoke 6.

(Problem to be Solved by the Invention) By the way, as mentioned above, since the stator 7 of the inner rotor type brushless motor has the slot 4 as shown in FIG. 3, the magnetic resistance between the stator 7 and the rotor 1 is It changes depending on the angle, causing torque unevenness called cogging, which causes rotational unevenness. The presence of this cogging causes speed fluctuations and acts like static friction, making it difficult to start the motor.

Furthermore, since the structure is such that the coil is wound through slot 4,
The drawback is that winding work is somewhat difficult and workability is poor.

In order to compensate for the above-mentioned drawbacks, there is a motor having a coil structure as shown in FIG. FIG. 4(a) is a sectional view thereof, and FIG. 4(b) is a perspective view showing the shape of the coreless coil. In the figure, parts equivalent to those in FIG. 3 are given the same reference numerals. In the figure, reference numeral 8 denotes a plurality of air-core coreless coils arranged on the inner circumferential surface of the yoke 6 without slots provided on the outer circumference. In this motor, the coreless coil 8 has no core, and the yoke 6 has no slot, so there is no cogging because the magnetic resistance does not change depending on the rotation angle. However, since a plurality of coreless coils are used, the space factor of the winding portion is poor, making it difficult to obtain a motor with good characteristics.

Furthermore, uneven rotation is likely to occur due to the shape in which the coreless coils 8 are arranged. Further, there is also a drawback that the workability of manufacturing is poor, such as winding the coreless coil 8 and pasting it to the yoke 6.

The present invention has been made in view of the above points, and its purpose is to:
The object of the present invention is to realize a brushless motor that is free from cogging, has little rotational unevenness, and has good manufacturing workability.

(Means for Solving the Problems) The present invention, which solves the above-mentioned problems, provides an inner rotor type brushless motor, which includes a rotor made of permanent magnets, and a suitable space between the rotor and the rotor. A single coreless coil that is continuously wound around the winding frame and has a plurality of taps in the middle to form a coil between each tap, and the coreless coil. A yoke that is uniform over the entire circumference forming a magnetic path of the rotor is provided on the outer circumference of the rotor.

(Operation) A single, uniformly wound coreless coil is arranged, and a rotor made of permanent magnets rotates in response to changes in the current flowing through the coil. This rotation is possible because the coil is coreless,
The yoke is arranged around the entire circumference, and there are no slots in the magnetic material, so there is no cogging, and rotational unevenness is small, resulting in smooth rotation.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a brushless motor according to an embodiment of the present invention. In the figure, parts equivalent to those in FIG. 3 are given the same reference numerals. In the figure, reference numeral 9 denotes a coreless coil as a field coil, which is wound around a winding frame 10 made of a non-magnetic material in a zelkova winding (sometimes called ball winding). Rotor 1 with a gap
It is designed to enclose the One end of the winding frame 10 is held by a housing 11, and the other end is held by a support plate 12. The motor is housed in a housing 11, and one end is covered by a cover 13. A bearing 14 rotatably couples the shaft 2 to the housing 11 and the cover 13.

FIG. 2 is a perspective view of the coreless coil 9. In the figure, the same parts as in FIG. 1 are given the same reference numerals. As shown in the figure, the coreless coil 9 is a single coil wound on a winding frame 10 while continuously changing the angle with respect to the central axis of the winding. This coreless coil 9 is provided with a plurality of taps 15, and has a structure in which electrically different coils each forming an independent magnetic pole are formed between each tap 15.

Next, the operation of the embodiment configured as described above will be explained.

The magnetic flux from the permanent magnets of the rotor 1 passes through a magnetic circuit formed by a yoke 7, and passes through a coreless coil 9 located in the middle thereof. The direction of the current flowing through the coreless coil 9 is appropriately changed according to the position of the magnetic pole of the rotor 1 to form a rotating magnetic field, which rotates the rotor 1 and the shaft 2 to output rotational force. The shaft 2 rotates through the bearing 14
through the yoke 6 and the coreless coil 9. Housing 11
etc. The yoke 6 is integral over the entire circumference, and the coreless coil 9 has no core, so the magnetic resistance does not change depending on the rotation angle, and therefore no cogging occurs. Furthermore, since the coreless coil 9 is wound continuously and uniformly around only one winding frame 10, rotational irregularities hardly occur.

Further, since the coreless coil 9 is uniformly wound around an independent winding frame 10, it is easy to manufacture and work efficiency is greatly improved. From the above, a motor with good output response to human power and good #J controllability for positioning can be obtained.

Note that the present invention is not limited to the above embodiments. In the embodiment, the method of winding the coreless coil 9 was described as a zelkova-like shape, but FIG.

(B) Figure, - (C) Figure, (D) Figure, (E) Figure, (
Either of the methods shown in Figures (f) and (G) may be used.

(Effects of the Invention) As explained in detail above, according to the present invention, it is possible to realize a brushless motor that is free from cogging, has little rotational unevenness, and has good workability in manufacturing, and has great practical effects. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a brushless motor according to an embodiment of the present invention, FIG. 2 is a perspective view of a coreless coil according to an embodiment of the present invention, FIG. 3 is a cross-sectional view of a conventional brushless motor, and FIG. 4 is a cross-sectional view of a conventional brushless motor. Figure 5 is a diagram of a brushless motor using a conventional slotless core, (A) is a cross-sectional view, (B) is a partial perspective view of the coil and yoke, and Figure 5 shows another way of winding the coreless coil. It is a figure of an Example. 1... Rotor 2... Shaft 3...
Core 5... Coil 7... Data 10... Winding frame 12... Support plate 14... Bearing 4... Slot 6... Yoke 8.9... Coreless coil 11... Housing 13...Cover 15...Tap

Claims (1)

[Claims] An inner rotor type brushless motor includes a rotor (1) made of a permanent magnet, and a rotor (1) provided on the outer periphery of the rotor (1) with an appropriate gap outside the rotor (1). A winding frame (10) made of a non-magnetic material, and a single coil that is continuously wound around the winding frame (10), with a plurality of taps (15) provided in the middle, and forming a coil between each tap (15). A brushless motor comprising: a coreless coil (9); and a yoke (6) that is uniform over the entire circumference and forms a magnetic path for the rotor (1) around the outer circumference of the coreless coil (9). .