JPS63178754A - Brushless motor - Google Patents

Abstract

PURPOSE:To restrain the generation of noise due to magnetic lines of force, by a method wherein respective surfaces of a magnet and an exciting coil, excluding the opposing surfaces of each parts, are covered by a magnetic material to prevent the magnetic lines of force from the magnet and the exciting coil from releasing to the outside of a motor. CONSTITUTION:A rotor 4 is constituted of a rotor main body 5 and annular magnet 6 while the magnet 6 is attached to the outer periphery of the rotor main body 5 through an annular upper fixing member 8, consisting of a magnetic material. On the other hand, an annular lower fixing member 9, consisting of the magnetic material, is fixed to a position opposing to the upper fixing member 8 of the bottom surface of a storing case 1, formed by the magnetic material, while an exciting coil 10 is arranged in the lower fixing member 9. A fan motor is constituted of the rotor 4, stored in the storing case 1 rotatably, and the storing case 1, however, respective surfaces excluding the mutual opposing surfaces of the magnet 6 and the exciting coil 10 are covered by the magnetic materials, therefore, releasing of magnetic lines of force to the outside of the motor may be prevented and the generation of noise may be restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a brushless motor used in small electric appliances and the like.

(Prior Art) A brushless motor for a fan, used in small electric appliances, etc., includes a rotor to which a flat annular magnet is attached, a stator for an excitation coil disposed close to the rotor, and a housing that accommodates these. The rotor frame and the storage case are made of a non-magnetic material such as resin that is easy to manufacture, lightweight and inexpensive.

For this reason, in this type of brushless motor, lines of magnetic force emitted from the magnet and excitation coil during operation of the motor pass through the rotor frame and the storage case to the outside, causing noise. Therefore, in the past, among small electric products, especially audio equipment and the like that are extremely sensitive to noise, in order to prevent the generation of noise, the entire motor has been covered or surrounded with a covering member or shielding member made of a magnetic material. There is.

However, there is a strong demand for two-part brushless motors to be smaller and lighter, and covering or surrounding the entire motor with a magnetic material as in the past would increase the size of the motor, increase the installation space, and increase the weight. This poses a problem in that it violates this request.

(Purpose) The present invention has been made in view of the following two problems, and its purpose is to remove the magnet and excitation coil within the brushless motor without increasing the size and weight of the brushless motor itself. An object of the present invention is to provide a brushless motor that can suppress noise caused by lines of magnetic force.

(Structure) In order to achieve the above-mentioned object, the present invention includes a rotor in which an annular magnet is fixed to the outer periphery of a rotor body having a fan, an excitation coil disposed at a position facing the magnet, and A brushless motor comprising a rotor and a storage case for storing an excitation coil,
The two-part storage case is entirely made of a magnetic material or has a shielding member made of a magnetic phase disposed on its inner surface, and the magnets of the rotor and the excitation coil of the stator are fixed in place by a fixed member made of a magnetic material. It is characterized in that each surface except for the mutually opposing surfaces is covered with a magnetic material.

(Example) The present invention will be described in detail below based on the illustrated example.

FIGS. 1 and 2 show an embodiment of the present invention as a drive motor for a cooling fan of a car audio system, and reference numeral 1 in the figures indicates a storage case for storing the motor.
The shaft 3 is formed of a magnetic material into a cylindrical shape with a bottom, and is erected at the center of the bottom surface in which a blow hole 5 is provided, and rotatably supports a rotor 4, which will be described later.

Reference numeral 4 denotes the above-mentioned rotor, which is composed of a rotor main body 5 formed of a synthetic resin material in the shape of a cylinder with a bottom, and an annular magnet 6 attached to the outer periphery of the rotor main body 5. A bearing portion 5a is provided in the center of the rotor body 5 for inserting the above-mentioned ll1Il13, and this bearing is provided with a plurality of bearings in the internal space from the portion 5a to the outer peripheral wall of the rotor body 5 for blowing air. The blades 7 are integrally formed.

Reference numeral 5b in the figure indicates a ventilation hole provided on the bottom surface of the rotor body 5.

The annular magnet 6 is polarized to be equally divided in the circumferential direction, and is attached to the outer periphery of the rotor body 5 via an upper fixing member 8. This upper fixing member 8 is formed of a magnetic material so as to have an annular cross-sectional shape, and the magnet 6 is fixed to the lower surface of the upper piece 8a, and the falling piece 8
b is attached to the outer periphery of the rotor body 5, and the outer periphery of the magnet 6 is open and faces the inner surface of the storage case 1. Also, at a position facing the upper fixing member 8 on the bottom of the storage case 1, Like the two-part fixing member 8, a ring-shaped lower fixing member 9 made of a magnetic material and having a U-shaped cross section is fixed with its opening surface facing upward. Inside the lower fixing member 9, excitation coils 10 are evenly arranged in a number corresponding to the number of polarizations of the magnets 6.

The shaft 3 of the storage case 1 is inserted into the bearing portion 5a of the rotor main body 5, and the rotor 4 is rotatably mounted in the storage case, thereby forming a fan motor. In this state, the surface of the magnet 6 and the surface of the excitation coil 10 are covered by the walls of the fixing members 8 and 9 made of magnetic material, except for the surfaces facing each other.

Therefore, when a magnetic pole detection element (not shown) detects the magnetic pole of the magnet 6 and sends a signal to a predetermined excitation coil 10, which is excited to the N pole or S pole to rotate the rotor 4 and operate as a motor. The lines of magnetic force emitted from the excitation coil 10 excite the excitation coil 10 without passing through the lower fixing member 9 covering both sides and the bottom of the excitation coil 10. Similarly, the lines of magnetic force weakened by this do not pass through the storage case 1, but only slightly magnetize it.

Furthermore, the magnetic lines of force from the magnet 6 are also sealed by the upper fixing member 8 except for the surface facing the excitation coil 10 and the outer circumferential surface, and the outer circumferential surface of the magnet is also sealed by the inner circumferential surface of the storage case 1 formed of a magnetic material. Therefore, it is not released outside the storage case 1.

Therefore, the noise generated by the magnetic lines of force of the magnet 6 and the exciting coil 10 is suppressed as much as possible. Also,
The size of both fixing members 8 and 9 that shield magnetic lines of force may be the same size as that for attaching the magnet 6 to the rotor body 5, and the space required is small, and there is no need to attach a magnetic member to the outside of the case 1, so the size of the entire motor is reduced. Size does not increase with weight.

In the above-described embodiment, the upper fixing member 8 for fixing the magnet 6 was formed in a cross-sectional shape.
The upper fixing member 18 may have the same structure as the lower fixing member 9, as shown in FIG.

According to this embodiment, lines of magnetic force from the magnet 6 can be more effectively shielded.

Furthermore, the storage case 21 does not need to be made entirely of a magnetic material, but can be made of a synthetic resin material as in the past, and has a thin plate made of a magnetic material on its inner circumferential surface as shown in FIG. 3 (b). It is also possible to attach a shield member 22 having an angled cross-section.

According to this embodiment, it is possible to provide a motor that is lighter in weight than the above-mentioned embodiment in which the entire storage case is made of magnetic material.

(Effects) As described above, according to the present invention, each surface of the magnet and the excitation coil except for the surfaces facing each other is covered with a magnetic material, so that the lines of magnetic force from the magnet and the excitation coil are directed to the outside of the motor. can be prevented from being emitted, and the generation of noise can be suppressed.

Further, according to the present invention, the fixing member for fixing the magnet and excitation coil, which are the sources of magnetic lines of force, to the rotor body etc. is made of a magnetic material, and the entire storage case is made of a magnetic material or the inner surface of the storage case is made of a magnetic material. Since the shield member made of a magnetic material is provided, the generation of the above-mentioned noise can be prevented without increasing the size or weight of the motor itself.

Furthermore, according to the present invention, since the magnet fixing member is formed of a magnetic material, the outer part of the rotor is slightly heavier, and inertia force is applied more than before, making it difficult to maintain a stable motor. It is something that can be rotated by gas.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a brushless motor showing one embodiment of the present invention, FIG. 2 is a sectional view thereof, and FIGS. 3(A) and 3(B) are sectional views showing another embodiment. 1.21...Storage case, 4...Rotor 5...Rotor body, 6...Magnet 7...Fan, 8,1
8... Upper fixing member 9... Lower fixing member, 10...
・Excitation coil 22...Shield member patent applicant Yamaki Electric Co., Ltd. agent Patent attorney Ue 1) Itsuki Shigeru 2nd figure 8b 3rd figure

Claims (3)

[Claims] (1) A rotor having an annular magnet fixed to the outer periphery of a rotor body having a fan, an excitation coil disposed at a position facing the magnet, and a storage case for storing the rotor and the excitation coil. In the brushless motor, the storage case is entirely made of a magnetic material or has a shield member made of a magnetic material disposed on its inner surface, and the magnet of the rotor and the excitation coil of the stator are made of a magnetic material. What is claimed is: 1. A brushless motor, characterized in that it is fixed in a predetermined position by a fixing member consisting of a brushless motor, and each surface except for mutually opposing surfaces is covered with a magnetic material. (2) The fixing member is made of a magnetic material and has a U-shaped cross section, and the fixing member for the magnet is
The magnet is housed in a U-shaped recess and is fixed to the outer periphery of the rotor body with the opening side facing down, and the excitation coil fixing member similarly houses the excitation coil inside the U-shape. 2. The brushless motor according to claim 1, wherein the brushless motor is fixed to the bottom surface of the storage case with the opening side facing upward, and the storage case is entirely made of a magnetic material. (3) The fixing member for the magnet consists of an annular body with an L-shaped cross section formed of a magnetic material.A magnet is fixed to the lower surface of one side of the annular body, and the other side is fixed to the outer periphery of the rotor body. The open outer circumferential surface faces the inner circumferential wall of the storage case made of magnetic material, while the lower surface of the magnet faces the excitation coil in the annular fixed member formed of magnetic material and having a U-shaped cross section. A brushless motor according to claim 1, characterized in that: