JPH07107713A - Rotor of brushless motor - Google Patents

Abstract

PURPOSE:To improve workability, and to shorten an operating time by also automating rotor unbalance correction conducted as the vibration countermea sure of a brushless motor by using a weldable metal and instantaneously welding the metal to a rotor yoke. CONSTITUTION:A rotor for a brushless motor has constitution, in which a rotor yoke 3 and a permanent magnet 5 fixed onto the outer circumferential section of the yoke and a rotor unbalance correction piece 3a consisting of a weldable metal at a rotor unbalanced point of the axial end face of the rotor yoke are welded and fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor of a brushless electric motor used as a blower fan driving source for household air conditioners, water heaters and the like.

[0002]

2. Description of the Related Art In recent years, it has become mainstream to control the capacity of a compressor in an air conditioner such as a home air conditioner. In response to this, it is required that the amount of air blown to the heat exchanger be widely adjusted in multiple stages.

In hot water heaters, a proportional control system for combustion has been adopted or combustion capacity has been increasing for the purpose of improving combustion efficiency, and multi-stage air flow rate adjustment and further higher air flow rate are required. Is becoming stronger.

In order to satisfy these demands, a method of operating a brushless motor whose speed is easily adjusted by a DC power source is being adopted in place of an induction motor used as a fan drive source which has been conventionally used.

On the other hand, there is a strong demand for low vibration of this type of electric motor, and a brushless electric motor which normally has a rotor made of a permanent magnet is usually rotated at a high speed in order to ensure a high air flow. The following two vibrations are often problems. (1) Due to imbalance during assembly of the rotor, which consists of the rotor yoke and permanent magnets. (2) Caused by the number of stator core slots of a brushless motor and the number of magnetized magnetic poles of a rotor permanent magnet (cogging).

The problem to be solved by the present invention is related to the first point. FIG. 3 shows a vertical sectional view of a conventional brushless motor rotor. In FIG. 3, 1 is a stator core, 2 is a drive circuit, 3 is a rotor yoke, 4 is a shaft, 5 is a permanent magnet, and 6 is a bearing. FIG. 4 is a sectional view of the rotor yoke. 3b is putty, 4 is a shaft, 5 is a permanent magnet, and 6 is a bearing. In the electric motor having the above structure, in order to correct the imbalance of the rotor yoke 3, a putty made of a component such as a varnish for correcting the rotor imbalance is attached to the axial end surface of the rotor yoke, and after drying and curing, Then, an adhesive was applied from above and strong fixation was performed.

[0007]

However, according to the above method, the following can be considered. (1) Because the conventional axial height is limited, it is difficult to accurately attach the required amount of component putty such as varnish to the rotor yoke, and the putty component should be stored in a storage location so that it does not change. Needs attention. (2) A step of drying and curing the putty attached to the rotor yoke and time are required. (3) To prevent peeling, an adhesive is required to be applied from above the putty, and it takes time to cure when the adhesive is applied.

[0008]

The present invention has the following constitution in order to solve the above problems. A rotor imbalance correction piece made of a metal having a specific gravity equal to or higher than that of the rotor yoke material is welded to the axial end surface of the rotor yoke to obtain the rotor of the brushless motor of the present invention.

[0009]

With the above configuration, the correction work can be easily performed when the rotor imbalance is corrected, and the correction work can be automated. Also, in the conventional putty, there is concern about peeling when the rotor is rotated at high speed, or there is no fear of peeling because the imbalance correction piece is welded to the rotor yoke,
Furthermore, adhesives for strong fixation and putty management are unnecessary.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a rotor imbalance correction state diagram of the brushless motor of the present invention. In FIG. 1, 3 is a rotor yoke, 4 is a shaft, 5 is a permanent magnet, 6 is a bearing, and 10 is a welding device. The rotor yoke 3 is formed by stacking iron plates, and the permanent magnet 5 is fixed to the outer peripheral portion of the rotor yoke 3 with an adhesive.

After confirming which part of the rotor is unbalanced by a rotor imbalance measuring device or the like, the same material as the rotor yoke 3 prepared for each gram at the rotor imbalance point is used. Alternatively, the correction piece 3a made of a metal (iron, brass, etc.) of specific importance is instantly welded and fixed by the welding device 10 such as spot welding, electron beam welding, or ultrasonic welding.

FIG. 2 is a sectional view of the rotor of the present invention. By holding the rotor imbalance-corrected rotor as described above rotatably by the bearing device 6, the rotor yoke 3,
The rotor assembly of the brushless electric motor as shown in FIG. 2 in which the vibration caused by the rotor imbalance composed of the permanent magnets 5 is suppressed is completed.

[0014]

As described above, the following effects can be obtained by using the configuration of the present invention. (1) Rotor imbalance correction can be automated, and the time required for correction can be shortened. (2) The workability is improved because the difficulty of putty correction due to the axial height limitation of the distance between the rotor and the stator, which can be a problem when assembling the brushless motor, is eliminated. (3) Putty such as varnish and adhesive are unchanged,
Eliminates the need for storage and management of changes in ingredients.

[Brief description of drawings]

FIG. 1 is a perspective view of a brushless motor rotor according to an embodiment of the present invention in an imbalance corrected state.

FIG. 2 is a vertical sectional view of a rotor according to an embodiment of the present invention.

FIG. 3 is a vertical sectional view of a conventional brushless electric motor.

FIG. 4 is a vertical sectional view of a conventional rotor.

[Description of Reference Signs] 3 rotor yoke 3a rotor imbalance correction piece 3b putty 4 shaft 5 permanent magnet 6 bearing 10 welding device

Claims (1)

[Claims] 1. A rotor yoke comprising: a rotor yoke obtained by laminating iron plates; and an annular permanent magnet or a plurality of arc-shaped permanent magnet pieces fixed to the outer surface of the rotor yoke. A rotor of a brushless electric motor in which a rotor imbalance correction piece made of a metal having a weldability with an iron plate is welded and fixed to the rotor imbalance point at the axial end face of.