JP2000324751A - DC brushless fan motor - Google Patents

Abstract

(57) [Summary] [PROBLEMS] A DC brushless fan motor mainly used for cooling electric equipment such as computers and copiers.
The vibration of the DC brushless fan motor itself, and the vibration suppresses the generation of vibration noise of members inside the motor.
An object of the present invention is to provide a low-noise DC brushless fan motor. SOLUTION: By making the magnetic centers of a permanent magnet 1 and a laminated core 3 coincide with each other, vibration in the thrust direction due to rotation of a rotor itself can be suppressed, and a cushioning material 14 is provided between an electronic component 7 and a circuit cover 13. By the insertion, it is possible to prevent the electronic component from vibrating due to the motor vibration and generating a collision sound with another member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC brushless fan motor for cooling electrical equipment such as computers and copiers.

[0002]

2. Description of the Related Art Conventionally, a DC brushless fan motor disclosed in Japanese Utility Model Laid-Open No. 3-12045 has been known. FIG. 4 shows the structure of a conventional DC brushless fan motor. In FIG. 4, reference numeral 1 denotes a rotor constituted by an annular permanent magnet, and a laminated core core 3 provided with a winding 2 is installed on the inner diameter side thereof.

The rotating shaft 4 of the rotor is held by a sintered oil-impregnated metal 5 as a bearing member and a ball bearing 6, and the winding 2 is controlled by a circuit board 8 on which an electronic component 7 is mounted.

Since the axial magnetic center 9 of the permanent magnet has an axial deviation from the magnetic center 10 of the laminated core 3, the permanent magnet rotor receives a magnetic thrust force in the direction of 11. Since the ball bearing 6 is pressed by the stopper 12 inserted into the groove of the rotating shaft 4, the ball bearing 6 can stably rotate without moving.

Reference numeral 13 denotes a frame portion which covers a circuit portion.

[0006]

However, in the above-mentioned conventional configuration, the axial axial height of the rotor is stabilized by the magnetic thrust force generated by the axial magnetic center displacement of the stator core and the axial magnetic center of the annular permanent magnet. In order to adopt the method, by the rotation of the rotor, the transition of the magnetic pole of the permanent magnet rotor and the relative position of the stator core,
Since the magnetic thrust force changes, the rotation of the rotor generates vibrations in the axial direction, and there is a problem in that when there are electronic components that are not easily mounted on the circuit board, they vibrate and generate noise.

There is also a problem that the vibration in the axial direction is transmitted to a device to which the DC brushless fan motor is attached and generates noise.

An object of the present invention is to solve such a conventional problem and to provide a DC brushless fan motor in which noise and vibration are suppressed.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a control circuit for switching and controlling a current flowing through a winding of a stator of a DC brushless fan motor in accordance with a position of a rotor, and a control circuit. A cushioning material for suppressing vibration of electronic components is provided between the motor cases.

[0010] Thus, the vibration of the electronic component whose mounting is unstable can be suppressed, and the noise generated by the vibration of the electronic component due to the vibration of the rotor can be eliminated.

In the present invention, since the axial magnetic center of the annular permanent magnet and the magnetic center of the stator core are set substantially equal, the magnetic thrust force is zero with respect to the axial direction, and is generated by rotation of the rotor. Since there is no change in the magnetic thrust force, generation of vibration in the axial direction can be suppressed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to an outer rotor having an annular permanent magnet, a stator having a laminated core as an iron core, and a current flowing through a winding of the stator at a position of the rotor. A control circuit that controls switching according to
A motor case that covers the control circuit; and a buffer material that suppresses vibration of the electronic component between the electronic component on the control circuit and the motor case. The vibration of the electronic component is suppressed, and the vibration of the rotor is reduced. Accordingly, the noise generated by the vibration of the electronic component can be eliminated.

According to a second aspect of the present invention, at least one surface of a cushioning member for suppressing vibration of an electronic component is coated with an adhesive material, and an assembly of a DC brushless fan motor in which vibration of the electronic component is suppressed. Has the effect of facilitating work.

According to the third aspect of the present invention, the cushioning member for suppressing vibration of the electronic component is made of a flame-retardant material having a thickness of 0.6 mm or more, so that a larger effect of vibration absorption can be secured safely. .

Next, according to a fourth aspect of the present invention, an outer rotor having an annular permanent magnet, a stator having a laminated core as an iron core, and a current flowing through a winding of the stator are switched and controlled according to the position of the rotor. A control circuit, a motor case covering the control circuit, and a rotating shaft retainer of an outer rotor provided in a center portion of the motor case is a sintered oil-impregnated metal; and an axial magnetic center of the annular permanent magnet and the stator. The magnetic center of the iron core is set substantially equal, and there is no member that slides in contact with the end face of the sintered oil-impregnated metal, and the magnetic thrust force is zero in the axial direction,
Since there is no change in the magnetic thrust force generated by the rotation of the rotor, there is an effect that generation of vibration in the axial direction can be suppressed.

According to a fifth aspect of the invention, the axial length of the annular permanent magnet is equal to or shorter than the axial length of the stator core, so that the axial position of the rotor is shifted from the position where the magnetic thrust force is zero. When this occurs, a strong magnetic thrust force is generated to work to correct the rotor to its original position, so that the rotor position can be maintained at a more stable position.

According to a sixth aspect of the present invention, when the inner diameter of the annular permanent magnet is small at the center in the axial direction and large at both end surfaces, the axial position of the rotor is shifted from the position where the magnetic thrust force is zero. In addition, since a stronger magnetic thrust force is generated to act to correct the rotor to the original position, the rotor position can be maintained at a more stable position.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) In FIG. 1, a cushioning material 14 having a large thickness is inserted between an electronic component 7 mounted on a circuit board 8 and a frame 13 covering a circuit portion.

FIG. 2 shows the details of the circuit portion shown in FIG. 1. As a more specific example of an electronic component which easily vibrates, the terminal 15 of the electrolytic capacitor 7 is formed and the circuit board 8 is formed.
And a shock-absorbing material 14 of a double-sided tape is attached to the surface of the electrolytic capacitor.

With the above configuration, the main body of the electrolytic capacitor 7 is adhered and fixed to the frame 13 of the circuit unit cover with a double-sided tape. Occurrence can be suppressed.

Also, the permanent magnet of FIG. 1 has an axial length shorter than the axial length of the laminated core,
Are set to coincide with each other, and the permanent magnet 1 is stably held at this position in the axial direction. At this time, retaining 1
2 does not slide on the end face of the sintered oil-impregnated bearing 5.

In this state, the magnetic thrust force of the rotor is zero irrespective of the rotational position of the rotor, and no axial vibration of the rotor occurs.

(Embodiment 2) In FIG. 3, the annular permanent magnet 16 has a small inner diameter at the center in the axial direction and a larger inner diameter at the end face.
Is configured to be equal to the magnetic center 10.

According to this embodiment, when the permanent magnet moves in the axial direction, the permanent magnet acts to hold the magnetic core at the magnetic center position of the laminated core 3 with a stronger magnetic thrust force. The rotor can be held in a stable position.

[0026]

As is clear from the description of the above embodiment,
According to the first, second and third aspects of the present invention, an advantageous effect of preventing the electronic component from vibrating and generating noise due to the vibration generated by the motor can be obtained.

According to the fourth and fifth aspects of the present invention,
This has an effect that the axial vibration itself generated by the rotation of the motor can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a DC brushless fan motor according to Embodiment 1 of the present invention.

FIG. 2 is a perspective view showing the configuration of electronic components of a DC brushless fan motor circuit and a vibration isolator according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing a structure of a DC brushless fan motor according to Embodiment 2 of the present invention.

FIG. 4 is a sectional view showing the structure of a conventional DC brushless fan motor.

[Explanation of symbols]

 1, 16 permanent magnet 2 winding 3 laminated core 4 rotating shaft 5 sintered oil-impregnated bearing 6 ball bearing 7 electronic component 8 circuit board 9, 19, 29 magnetic center of permanent magnet 10 magnetic center of laminated core 11 action of magnetic thrust force Direction 12 Retaining 13 Motor case 14 Buffer material 15 Lead of electronic parts

Claims (6)

[Claims] An outer rotor having an annular permanent magnet, a stator having a laminated core as an iron core, a control circuit for switching and controlling a current flowing through a winding of the stator according to a position of the rotor, and a control circuit are covered. A direct current brushless fan motor comprising: a motor case; and a buffer material for suppressing vibration of the electronic component between the motor case and an electronic component on the control circuit. 2. The DC brushless fan motor according to claim 1, wherein at least one surface of the cushioning member for suppressing vibration of the electronic component is coated with an adhesive. 3. The direct current brushless fan motor according to claim 1, wherein the thickness of the cushioning member for suppressing vibration of the electronic component is made of a flame-retardant material having a thickness of 0.6 mm or more. 4. An outer rotor having an annular permanent magnet, a stator having a laminated core as an iron core, a control circuit for switching and controlling a current flowing through a winding of the stator according to a position of the rotor, and a control circuit. The motor case and the rotary shaft retainer of the outer rotor provided at the center of the motor case are made of sintered oil-impregnated metal, and the axial magnetic center of the annular permanent magnet and the magnetic center of the stator core are set substantially equal. A DC brushless fan motor having no member that slides on the end surface of the sintered oil-impregnated metal. 5. The DC brushless fan motor according to claim 4, wherein an axial length of the annular permanent magnet is equal to or shorter than an axial length of the stator core. 6. The DC brushless fan motor according to claim 4, wherein the inner diameter of the annular permanent magnet is small at the axial center portion and large at both end surfaces.