JP2995759B2 - Motor rotation detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation detecting device for a motor, and more particularly, to a rotor yoke which holds a magnet arranged to face a stator coil via an air gap. The present invention relates to improvement of a position detecting magnet.

[Summary of the Invention]

In a motor in which the position detection magnet is attached to the rotor, the position detection magnet is outsert only to the necessary parts, compared to the conventional structure in which a plastic magnet or a rubber magnet is attached by gluing all around. The rotor yoke is formed directly on the rotor yoke by injection, reducing the number of steps for bonding the position detecting magnet and reducing the cost. In addition, two types of notches are formed in the rotor yoke to cancel the unbalanced position detecting magnet weight. And the angle of one of the notches is changed to obtain an ideal balance easily.

[Conventional technology]

The rotor of the conventional flat type brushless DC motor has a structure as shown in FIGS. 3 and 4, in which a rotor magnet 2 is mounted on a rotor yoke 1, and
The position detecting magnet 3 is mounted on the outer peripheral surface of the rotor yoke 1. In addition to this structure,
A rotor as disclosed in JP-A-56-166673 is also used.

[Problems to be solved by the invention]

In general, the weight of the rotor is considerably reduced with the miniaturization and high output of the motor. However, as shown by N and S in FIG. 3, only a part of the position detecting magnet 3 is originally used, but the magnet 3 is added to the entire circumference of the rotor yoke 1 from the viewpoint of weight balance. I have. This will unnecessarily increase material costs. When the position detecting magnet 3 is mounted on the same plane as the driving magnet 2, it is necessary to separately magnetize the driving magnet 2 and the position detecting magnet 3 under the influence of the magnetizing magnetic field. is there. Also, for handling products by bonding the rubber magnet 3,
The number of man-hours has increased, which is a negative factor for measures such as automation.

Therefore, attaching a position detecting magnet to a part of the outer peripheral portion of the rotor is considered. Generally, the movement of the eccentricity is negligible for a rotor having a large weight. However, when the size of the motor is reduced, the weight of the rotor is also reduced. If the function of the position detecting magnet is to be satisfied with the downsizing of the motor, the shape of the position detecting magnet is determined to some extent due to restrictions on magnetic characteristics and the like. For this reason, the weight of the position detecting magnet with respect to the total weight of the rotor tends to increase, the movement of the eccentricity cannot be ignored, and the eccentricity needs to be adjusted.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and has a motor rotation detecting device that minimizes the size of a position detecting magnet and that can easily perform balance adjustment. It is intended to provide.

[Means for solving the problem]

The present invention provides a motor in which a magnet is mounted on a rotor yoke so as to face a stator coil via an air gap, and a position detecting magnet is mounted on the rotor yoke, and the rotational position of the rotor is detected by the position detecting magnet. A rotation detecting device, wherein a flange is provided on an outer peripheral portion of a rotor yoke to which the magnet is attached, and the position detecting magnet is locally attached in a circumferential direction at a predetermined position on the flange; A part of the outer peripheral portion of the flange portion is cut off on both sides of a portion where the position detecting magnet is attached, so as to balance the weight of the position detecting magnet.

[Action]

Therefore, the position of the rotor is detected by the position detecting magnet attached to the flange on the outer peripheral portion of the rotor yoke. The imbalance of the weight due to the mounting of the position detecting magnet is adjusted by cutting out both sides of the position where the position detecting magnet is mounted, which is a part of the outer peripheral portion of the flange portion.

〔Example〕

1 and 2 show a rotor 10 of a motor provided with a rotation detecting device according to an embodiment of the present invention,
The rotor 10 has a rotor yoke 11. The rotor yoke 11 has a circular opening 12 formed at the center thereof and a ring-shaped magnet 13 on the rotor yoke 12.
Can be attached. The magnets 13 are alternately magnetized in the circumferential direction to the respective polarities of N and S, and constitute a driving magnet. A flange 14 is formed at a position on the outer peripheral side of the rotor yoke 11 and on the outer peripheral side of the magnet 13. And this flange 14
A position detecting magnet 15 is attached to a predetermined position of the control unit. In order to balance the eccentricity of the magnet 15, the rotor yoke 11 has a flange portion.
A notch 18 is formed on both sides of the magnet 15 in the magnet 14, and a pair of notches 19 are formed at positions slightly away from the notch 18.

Conventionally, the position detecting magnet is arranged over the entire circumference, and only the portion used as the position detecting magnet has a function as a dummy weight except for the portion used as the position detecting magnet. In this embodiment, as shown in FIG. The position detecting magnet 15 is mounted on the flange 14 of the rotor yoke 11 by outsert molding. The imbalance caused by molding the position detecting magnet 15 on the rotor yoke 11 is due to the notch formed on the flange
It is made to be canceled by 18, 19.

The notches 18 and 19 for canceling the eccentricity of the position detecting magnet 15 will be described in more detail.The notches 18 on both sides of the magnet 15 are used to remove the unbalanced weight generated by the position detecting magnet 15. Cancel to some extent. The final balance adjustment is performed by another notch 19 located far from the magnet 15, and the shape of the notch 19 can be set arbitrarily. Further, the final fine adjustment of the balance is performed by the angles θ and θ ′ of the notch 19 located far from the magnet 15 from the magnet 15. By performing fine adjustment by the angular position θ, θ 'of the notch 19, compared to balancing based on the shape of the notch 19,
Shape determination can be performed quickly. Further, a change in the mass of the position detecting magnet 15 can be promptly dealt with only by adjusting the angle of the notch 19. Therefore, by such fine adjustment, the rotor 10 can be stably produced.

Thus, the position detecting magnet 15 according to the present embodiment
Are formed on the flange 14 of the rotor yoke 11 by outsert molding.
At the same time, magnetization is performed. Therefore, the size of the position detecting magnet 15 can be reduced, and the cost can be reduced, and the magnetizing process can be reduced by the simultaneous magnetization with the driving magnet 13. Also, there is no need to attach or adhere the position detecting magnet 15, and a large number of man-hours can be reduced. In addition, since the balance is adjusted by the notches 18 and 19, the magnet provided locally
Adjustment of balance of 15 becomes easy. In particular, since the fine adjustment is performed by adjusting the angle of the position where the notch 19 is formed, precise balance adjustment can be quickly performed.

〔The invention's effect〕

As described above, according to the present invention, a flange portion is provided on the outer peripheral portion of a rotor yoke to which a magnet is attached, and a position detecting magnet is locally attached in a circumferential direction at a predetermined position on the flange portion. A part of the outer peripheral portion of the portion is cut off on both sides of a portion where the position detecting magnet is attached so as to balance the weight of the position detecting magnet.

Therefore, according to such a configuration, the position can be detected by the position detecting magnet of a required small size which is locally attached to the flange portion of the rotor yoke in the circumferential direction. Moreover, the imbalance due to the local installation of such a magnet for position detection is a part of the outer peripheral portion of the flange portion, and both sides of the portion where the magnet for position detection is mounted are cut off. Thus, adjustment can be easily performed, and it is not necessary to attach a counter balance or attach a continuous ring-shaped magnet to the entire circumference in the circumferential direction.

Another notch is provided at a position distant from the magnet with respect to the notch on both sides of the portion where the position detecting magnet is attached, which is a part of the flange portion of the rotor yoke, and the shape of the other notch According to the configuration in which the balance is finely adjusted by shifting the circumferential position without changing the position, fine adjustment of the balance is performed by shifting the circumferential position of the other notch. As a result, the imbalance caused by the position detecting magnet is adjusted more accurately.

According to the configuration in which the position detecting magnet is attached to a part of the flange portion of the rotor yoke by outsert molding, the mounting of the position detecting magnet to the flange portion of the rotor yoke is facilitated.

[Brief description of the drawings]

1 is a plan view of a rotor of a motor according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line II-II in FIG. 1, FIG. 3 is a plan view of a conventional rotor, and FIG. IV to IV in Fig. 3
It is a line sectional view. The names of the main parts in the drawings are as follows. 10 Rotor 11 Rotor yoke 13 Ring magnet 14 Flange 15 Position detecting magnet 18, 19 Notch

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01P 3/00-3/495 G01D 5/00-5/252 H02K 15/00-15/16

Claims (3)

(57) [Claims] 1. A magnet is mounted on a rotor yoke so as to face a stator coil via an air gap, and a magnet for position detection is mounted on the rotor yoke, and the rotational position of the rotor is detected by the magnet for position detection. In the motor rotation detecting device, a flange is provided on an outer peripheral portion of a rotor yoke to which the magnet is attached, and the position detecting magnet is locally attached in a circumferential direction at a predetermined position on the flange. A part of the outer peripheral portion of the flange portion of the rotor yoke, which is cut off on both sides of a portion where the position detecting magnet is mounted, to balance the position corresponding to the weight of the position detecting magnet. Motor rotation detecting device. 2. A notch, which is a part of a flange portion of the rotor yoke and on both sides of a portion where the position detecting magnet is mounted, is further provided at a position distant from the magnet. 2. The motor rotation detecting device according to claim 1, wherein the balance is finely adjusted by shifting the position in the circumferential direction without changing the shape of the other notch. 3. The motor rotation detecting device according to claim 1, wherein the position detecting magnet is attached to a part of a flange portion of the rotor yoke by outsert molding.