JPH0526914Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention relates to a rotor structure for a small synchronous motor.

(Prior Art) As a rotor structure of a small synchronous motor, there is one in which an inertia plate, which determines the rotational characteristics of the motor, is integrally fixed to one end surface of a rotor magnet by resin molding. This example will be explained in FIGS. 5 and 6. The rotor 50 consists of a short cylindrical rotor magnet 51, an annular inertia plate 52 disposed on one end surface of the rotor magnet 51, and a rotor boss portion 53 having a rotation center hole 53a. The rotor magnet 51 and the inertia plate 52 are inserted and fixed when the rotor boss portion 53 is molded in a superimposed state. The rotor magnet 51 and the inertia plate 52 are positioned in the rotation axis direction by flange-shaped molded parts 53b and 53c at both ends of the rotor boss part 53. The inertia plate 52 has a pair of recesses 52b, 52 at symmetrical positions on its inner peripheral edge 52a.
b is formed. A portion of the resin wraps around these recesses 52b during molding of the rotor boss, and positions the rotor boss and the inertia plate in the radial direction and rotational direction, respectively. The rotational characteristics of the motor are changed by selecting inertia plates 52 with different masses. In this case, inertia plates 52 whose inner peripheral edges have different diameters are used. No matter which inertia plate is selected, the recess 52 of the inertia plate 52
b is covered by one flange-shaped molded part 53c.

(Problem to be solved by the invention) In the rotor structure of the motor configured as described above, when inertia plates with different inner diameters are used to change the rotational characteristics of the motor, the outer diameter of the inertia plates changes. Since the inertia plate is not attached, it is not possible to judge the characteristics of the motor just by looking at the inertia plate exposed to the outside. Therefore, it is necessary to attach an identification mark to the rotor, which poses a problem of increased cost. Another problem is that due to the shrinkage of the resin after molding, a gap is created between the inner circumferential edge 52a and recess 52b of the inertia plate and the rotor boss 53 that should be in contact with them, causing looseness between them. There is a problem that occurs.

(Means for Solving the Problems) The present invention has a circular inertia plate on one end surface of a cylindrical rotor magnet, and the rotor magnet is sandwiched between both ends of a resin-molded rotor boss. In a rotor structure of a motor in which a flange-like molded part is formed, an engaging part consisting of a concave part facing outward in the radial direction or a convex part facing inward in the radial direction of the rotor magnet is formed on the inner peripheral edge of the inertia plate. death,
A part of the inner peripheral edge is covered by a flange-shaped molded part of the inertia plate, a part of the engaging part is exposed, and the inertia plate is integrated with the rotor magnet by the flange-shaped molded part. shall be.

(Function) In a rotor in which an inertia plate and a rotor magnet are integrated by resin insert molding, a portion of the engaging portion is exposed to the outside. The contracting resin bites into the constriction provided in the engaging portion.

(Example) Hereinafter, the present invention will be explained in detail based on the illustrated example.

In FIG. 1, a rotor 1 includes a short cylindrical rotor magnet 2, an annular first type inertia plate 3 disposed on one end surface 2a of the rotor magnet 2, and a rotor boss portion 4 having a rotation center hole 4a. It is made up of The rotor magnet 2 and the inertia plate 3 are inserted and fixed when the rotor boss portion 4 is molded in a superimposed state. The rotor magnet 2 and the inertia plate 3 are positioned in the rotation axis direction by flange-shaped molded parts 4b and 4c formed at both ends of the rotor boss part 4. At symmetrical positions on the inner circumferential edge 3a of the inertial plate 3, engaging portions 3b, 3b are formed, which are a pair of recesses cut outward in the radial direction. Engagement parts 3b, 3
b has a partially arcuate edge, and the length of a line connecting two points where this edge intersects with the inner peripheral edge 3a is set smaller than the diameter of the engaging portion. In other words, the engaging portion 3b has a constricted portion that contacts the inner peripheral edge thereof. Parts of the resin 4d, 4d are wrapped around these engaging parts 3b, 3b during molding of the rotor boss part, and position the rotor boss part and the inertia plate in the radial direction and rotational direction, respectively. . In this case, the flange-shaped molded portion 4c formed on the inertia plate side is molded so that a portion of the engaging portions 3b, 3b are exposed to the outside, as clearly shown in FIG. In other words, the flange-shaped molded portion 4c is formed to have a width that allows the shapes of the resins 4d, 4d poured into the engaging portions 3b, 3b to be recognized. When the resin contracts after resin molding, the resin 4 that has wrapped around the engaging parts 3b, 3b
d and 4d bite into the constricted portions 3c, 3c... of the engaging portions, eliminating "backlash" between the rotor boss and the inertia plate. In addition, the flange-shaped molded part 4c
Although the width is narrower than that of the conventional example shown in FIG. 5, it goes without saying that it is wide enough to integrally fix the rotor magnet 2 and the inertia plate 3. Further, the number of engaging portions 3b is not limited to the number shown in the drawings, and three or more may be formed. As shown in FIG. 1, by looking at the shapes of the engaging portions 3b, 3b exposed to the outside, it can be seen that the characteristics of this rotor are of the first type.

Next, to manufacture rotors with different rotational characteristics, inertia plates with different masses are prepared and insert molded.

In FIGS. 3 and 4, the inertia plate 3A has the same outer diameter as the inertia plate 3, but has a second type of mass with a larger inner diameter. The inner peripheral edge 3Aa is provided with a pair of engaging portions 3Ab, 3Ab and an engaging portion 3Ac, respectively.
3Ac is formed. Each of these engaging portions is formed as a convex portion that protrudes inward in the radial direction from the inner peripheral edge 3Aa. One of the engaging portions 3Ac, 3Ac has a constricted portion 3Ad formed at the intersection of the edge and the inner peripheral edge 3Aa, respectively.

The rotor magnet 2 and the inertia plate 3A are inserted and fixed when the rotor boss portion 4A is molded in a superimposed state. The rotor magnet 2 and the inertia plate 3A are positioned in the direction of the rotation axis by flange-like forming portions 4Ab and 4Ac formed at both ends of the rotor boss portion 4A. One of the flange-shaped molded parts 4Ac is formed by pressing down each of the engaging parts 3Ab and 3Ac from above as shown in the figure, and wrapping around to fill the space between the adjacent engaging parts 3Ab and 3Ac. There is. When the flange-shaped molded part 4Ac contracts after resin molding, the engaging parts 3Ac, 3Ac
The resin that had been wrapped around the constriction portions 3Ad, . . . bites into the constricted portions 3Ad, . The flange-shaped molded portions that hold down the respective engaging portions are molded in anticipation of shrinkage after molding, and have a width sufficient to hold down the respective engaging portions after shrinkage. In this case, when the rotor 1A after molding is viewed from the inertia plate 3A side in the axial direction, there are four inward engaging parts 3 around the flange-shaped molded part 4A.
Ab, 3Ab, 3Ac, and 3Ac are observed, indicating that it is a second type rotor.

(Effects of the invention) As described above, according to the invention, since a part of the engaging portion of the inertia plate is formed to be exposed to the outside, the motor can be characteristics can be easily identified. In addition, if a constriction is provided in the engagement part, when the resin contracts after molding, the resin that has wrapped around the engagement part will bite into the constriction, thereby suppressing rattling between the rotor boss and the inertia plate. It will be done.

[Brief explanation of drawings]

Fig. 1 is a plan view showing an embodiment of the rotor structure of the motor of the present invention, Fig. 2 is a longitudinal sectional view of the same, and Fig.
The figure is a plan view showing another embodiment of the present invention, Fig. 4 is a longitudinal cross-sectional view of the same as above, Fig. 5 is a plan view showing a conventional example of the present invention, and Fig. 6 is a longitudinal cross-sectional view of the same as above. . 1, 1A... Rotor, 2... Rotor magnet, 2a... One end surface, 3, 3A... Inertia plate, 3
b, 3Ac...engaging portion, 3c, 3Ad...constriction portion.

Claims (1)

[Claims for Utility Model Registration] 1. A flange-shaped molded part that has an annular inertia plate on one end surface of a cylindrical rotor magnet and that sandwiches the rotor magnet at both ends of a resin-molded rotor boss part. In the rotor structure of the motor, an engaging portion consisting of a concave portion extending radially outward or a convex portion radially inward of the rotor magnet is formed on the inner peripheral edge of the inertia plate, and the inertia plate A motor characterized in that a part of the inner peripheral edge is covered by a flange-shaped molded part, a part of the engaging part is exposed, and the inertia plate is integrated with the rotor magnet by the flange-shaped molded part. rotor structure. 2. Utility model registration claim 1, characterized in that the engaging portion has a constricted portion formed at a portion where the engaging portion intersects with the inner circumferential edge of the inertial plate.
Rotor structure of the motor described in section.