JPH08163814A - Brushless motor and balancing method for rotor thereof - Google Patents

Abstract

PURPOSE: To balance the rotation of a rotor by fixing ceramic balance rings on the opposite sides of a permanent magnet to the rotary shaft of a brushless motor and then cutting the balance ring by means of a laser beam. CONSTITUTION: A rotor 10 having a permanent magnet 4 is disposed in a stator generating a rotating field and rotates to follow up the rotating field. The rotor 10 carries ceramic balance rings 3 on the opposite sides of the permanent magnet 4. It is subjected to balance test without applying a bearing 2 the ceramic material is cut off by means of a laser beam while carrying out the balance test thus balancing the rotation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor, more specifically, a brushless motor suitable for use as a micromotor used for cutting teeth in dental treatment.
And a method for balancing the rotation of the rotor.

[0002]

2. Description of the Related Art In dental treatment, a micromotor is used for cutting teeth and the like. As this micromotor, a brush motor of 2000 to 40,000 rpm is generally used. However, the brushed motor has a problem that dust is generated from the brush during rotation, which is not only unsanitary but also shortens the life of the motor.

[0003]

Therefore, recently,
Although it has been attempted to use a brushless motor that does not use a brush, it is difficult to balance the rotation of this brushless motor.If the rotation is not well balanced, problems such as uneven rotation and noise may occur. there were.

The present invention has been made in view of the above-mentioned circumstances, and has been made in particular for the purpose of providing a brushless motor in which rotation balance can be easily taken.

[0005]

In order to solve the above problems, the present invention provides (1) a stator for generating a rotating magnetic field,
In a brushless motor including a rotor having a permanent magnet that rotates following the rotating magnetic field, the rotor is
It has a balance ring made of a ceramic material at both ends of the permanent magnet, or in the rotor balance adjustment described in (2) and (1), the ceramic material is balanced by cutting with a laser beam. It is a thing.

[0006]

[Function] The balance shaft made of a ceramic material is attached to both sides of the permanent magnet on the rotary shaft of the brushless motor, the rotary shaft is put on a rotation balance tester, and the rotary balance is cut while cutting the ceramic material with a laser beam. adjust.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view for explaining an example of a rotor used in a brushless motor according to the present invention, and FIG. 2 is a view showing a state in which the rotor is arranged in a stator.
In the figure, 10 is a rotor and 20 is a stator (rotating magnetic field generating portion), and the rotor 10 is composed of a rotating shaft 1, a permanent magnet 2, a bearing 3, a balance ring 4 made of a ceramic material and the like. This ceramic balance ring 4 is added according to the present invention, and the balance rings 4 are integrally attached to the rotary shaft 1 on both sides of the permanent magnet 2. As shown in FIG. 2, the rotor 10 is arranged in a coil (stator) 20 that generates a rotating (or alternating) magnetic field, and rotates following a change in the rotating (or alternating) magnetic field.

Thus, in dental treatment, a micromotor is used for cutting teeth, and the rotation speed of this micromotor is usually 2000 to 40,000 rpm, and the rotation balance is If it is bad, especially at high speed rotation, not only will vibration occur and abnormal noise will be generated,
Since the center of rotation is deviated, there is a problem that treatment work is very difficult. Further, since it rotates eccentrically, there is a risk that the rotary shaft may be broken or the bearing may be damaged.

As one means for solving the above-mentioned problems, it is conceivable to accurately balance the rotation of the rotor. Conventionally, the balancers provided on both sides of the permanent magnet are cut. However, it is difficult to perform the cutting amount accurately. Further, if the balancer is a magnetic material, there is a problem that the cutting powder adheres to the permanent magnet.

The present invention has been made in view of the above-mentioned circumstances, and as shown in the figure, a balance ring 4 made of a ceramic material is attached to both sides of the permanent magnet 2 of the rotor 10.
The balance ring 4 made of this ceramic material is cut by a laser beam so as to balance the rotation. In order to balance the rotation, in FIG. 1, the bearing 3 is not attached, that is, the permanent magnet 2 is attached to the rotary shaft 1.
With the balance ring 4 of ceramic material attached,
Apply a balance tester and observe the balance state while rotating the rotary shaft 1. When the balance is not balanced, irradiate a laser beam to cut a part of the ceramic material (cutting amount,
Consider the cutting point) and repeat this several times to balance the rotation.

[0011]

As is apparent from the above description, according to the present invention, the rotational balance of the brushless motor used in the dental micromotor can be adjusted relatively easily and accurately. Since the micromotor using the brushless motor has almost no vibration and no runout, dental treatment work is very easy. Further, it is possible to provide a micromotor that does not generate noise and has a long life. Furthermore, since ceramic is used as the material of the balancer, cutting with a laser beam is easy, and in particular, the cutting amount can be easily changed by changing the power of the laser beam, so that a predetermined amount of ceramic can be accurately obtained. It can be cut. Further, since the ceramic material is non-magnetic, the cutting powder does not adhere to the permanent magnet, and the balance adjustment work is very easy.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating an example of a rotor of a brushless motor according to the present invention.

FIG. 2 is a sectional view of an essential part of a brushless motor according to the present invention.

[Explanation of symbols]

1 ... Rotating shaft, 2 ... Permanent magnet, 3 ... Bearing, 4 ... Balance ring, 10 ... Rotor, 20 ... Stator.

Claims (2)

[Claims] 1. A brushless motor comprising a stator that generates a rotating magnetic field and a rotor that has a permanent magnet that rotates following the rotating magnetic field, wherein the rotor has a balance ring made of a ceramic material at both ends of the permanent magnet. A brushless motor characterized by having. 2. A rotor balance adjusting method for a brushless motor according to claim 1, wherein the ceramic material is balanced while being cut with a laser beam.