JPH0555742U - Small motor rotor - Google Patents

Abstract

(57) [Abstract] [Purpose] The purpose is to reduce the unit cost of magnets, the manufacturing cost of the rotating shaft with gears, and ensure the engagement of each part. [Structure] A geared rotary shaft 1 is fitted in an annular magnet 2. The rotating shaft 1 with gears is made of a synthetic resin such as polyacetal resin, and the whole is composed of a tubular portion 1b, a collar portion 1c and two wing-shaped portions.
It is formed with 1d. The collar 1c has two elastic pieces 1e, 1e.
And mountain-shaped axial engaging portions 1f, 1f on the front side of the two wing-shaped portions 1d
Rotating direction detents 1g, 1g consisting of notches on the collar 1c
A shaft-shaped centering portion 1h is formed on the outer circumference of one side of the tubular portion 1b, and a gear 1i is formed on the outer circumference of the other side of the tubular portion 1b. The annular magnet 2 is a synthetic resin magnet made of polar anisotropic plastic ferrite or the like, and the annular magnet 2 has an inner circumference 2a and an inner wall 2b.
The inner wall 2b is provided with engaged portions 2c and 2c formed of square holes and a cylindrical portion 2d formed of a through hole, and the inner periphery 2a has a protrusion-shaped engaged portion 2
e and 2e are formed.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a rotor for a small motor such as a permanent magnet type stepping motor.

[0002]

[Prior Art]

 Conventionally, in the rotor of a permanent magnet type stepping motor, an isotropic sintered ferrite magnet was used to make bosses and gears by insert molding of polyacetal resin. Since the unit price is high and the magnet is arranged in the mold in the insert molding, there is a drawback that the assembly cost becomes high. Further, there is a rotor including a powder-molded magnet such as barium ferrite or samarium cobalt and a rotor cana or a rotor shaft as disclosed in, for example, Japanese Utility Model Publication No. 57-57503. However, in this structure, since the rotor shaft pushes the fitting portions of the magnets of the rotor cana to expand and fix them, there is no circumferential engaging portion between the rotor cana and the magnet. Since there is no axial engaging portion, there is a drawback that the circumferential and thrust positions are not stable.

[0003]

[Problems to be solved by the device]

 The problems to be solved are that the unit price of the magnet is high in the conventional rotor, the cost is high in the insert molding, there is no circumferential engagement part between the rotor cana and the magnet, and the axial direction Since there is no engaging part, the position in the circumferential direction and the thrust direction is not stable. In view of the above-mentioned drawbacks, an object of the present invention is to propose a rotor for a small motor in which the unit cost of the magnet and the manufacturing cost of the rotary shaft with a gear are reduced, and the engagement of each part is ensured.

[0004]

[Means for solving the problem]

 The present invention is a rotor of a small motor composed of a rotating shaft with gears and an annular magnet. The rotating shaft is made of synthetic resin, and the shaft with the elastic piece and the magnet pressed against the inner circumference of the annular magnet. A direction engaging portion, a rotation preventing portion with respect to the rotation direction with the magnet, and an axial centering portion, and the annular magnet is a synthetic resin magnet, and the engaged portion engaging with the axial engaging portion, The gist of the invention is that it has an engaged part that engages with the rotation stopping part and a tubular part into which the centering part fits, and that the rotary shaft and the ring magnet are fitted and integrated.

[0005]

[Action]

 When the rotary shaft 1 with gears is fitted in the annular magnet 2, the centering portion 1h is fitted in the tubular portion 2d formed of a through hole, and the projection-like engaged portions 2e, 2e are cut from the notches. The rotation direction detents 1g, 1g are aligned. Next, when the rotary shaft 1 with gears is pushed into the ring-shaped magnet 2, the rotation direction detent parts 1g, 1g are fitted and engaged with the engaged parts 2e, 2e, and the engaged parts composed of square holes are engaged. The front ends of the two wing portions 1d are inserted into the portions 2c, 2c so that the axial engagement portions 1f, 1f are engaged with the edges of the inner wall 2b. At this time, the two elastic pieces 1e, 1e are pressed against the inner circumference 2a, and the rotation direction detents 1g, 1g made of the notches and the projection-like engaged parts 2e, 2e are fitted and engaged by snap fit. The left side of the collar portion 1c in FIG. 1 is pressed against the hitting portion 2f so that the rotary shaft 1 with a gear and the annular magnet 2 are fitted and integrated.

[0006]

【Example】

 The present invention will be described below with reference to the illustrated embodiment. 1 is a cross-sectional side view of the main part of a circular rotor magnet of a small motor, FIG. 2 is a front view of the rotor of the small motor, and FIG. 3 is a rotary shaft with gears ( a) side view and (b) front view, FIG. 4 shows (a) sectional front view of the annular magnet, (b) shows sectional side view taken along line bb of (a), and FIG. Side view, FIG. 6 is a cross-sectional side view taken along the line aa of FIG.

In the rotor of the small motor shown in FIGS. 1 and 2, the rotary shaft 1 with a gear is fitted in an annular magnet 2. A shaft (not shown) is fitted in the central shaft hole 1a of the rotary shaft 1 with gears. FIG. 1 shows a state where the rotary shaft 1 with gears of FIG. 5 is fitted to the annular magnet 2 of FIG. 4 (b).

The rotary shaft 1 with gears is made of a synthetic resin such as polyacetal resin, and as shown in FIGS. 1 to 3, 5 and 6, the whole is composed of a tubular portion 1b, a collar portion 1c and two wing portions. It is formed with 1d. The collar portion 1c has two elastic pieces 1e, 1e, mountain-shaped axial engaging portions 1f, 1f on the front sides of the two wing-shaped portions 1d, and a rotation-direction detent portion 1g including a notch in the collar portion 1c. , 1g, a shaft-shaped centering portion 1h on one outer periphery of the tubular portion 1b, and a gear 1i on the other outer periphery of the tubular portion 1b.

The annular magnet 2 is a synthetic resin magnet made of polar anisotropic plastic ferrite or the like. As shown in FIGS. 1, 2, and 4, the annular magnet 2 has an inner circumference 2 a and an inner wall 2 b. The inner wall 2b is provided with engaged portions 2c and 2c formed of square holes, and a cylindrical portion 2d formed of a through hole, and the inner periphery 2a is provided with protruding engaged portions 2e and 2e and engaged portions. Abutting portions 2f are formed on both sides of 2c, 2c and on both sides of the engaged portions 2e, 2e.

When the rotary shaft 1 with gears is fitted in the annular magnet 2, the centering portion 1h is fitted in the cylindrical portion 2d made of a through hole, and the protruding engaged portions 2e, 2e are fitted. The rotation direction detents 1g and 1g, which are notches, are aligned. Next, when the rotary shaft 1 with gears is pushed into the ring-shaped magnet 2, the rotation direction detent parts 1g, 1g are fitted and engaged with the engaged parts 2e, 2e, and the engaged parts composed of square holes are engaged. The front ends of the two wing portions 1d are inserted into the portions 2c, 2c so that the axial engagement portions 1f, 1f are engaged with the edges of the inner wall 2b. At this time, the two elastic pieces 1e, 1e are pressed against the inner circumference 2a, and the rotation direction detents 1g, 1g made of the notches and the projection-like engaged parts 2e, 2e are fitted and engaged by snap fit. The left side of the collar portion 1c in FIG. 1 is pressed against the hitting portion 2f so that the rotary shaft 1 with a gear and the annular magnet 2 are fitted and integrated.

When the rotor of the small motor is constructed as described above, the annular magnet 2 is formed of a synthetic resin magnet made of polar anisotropic plastic ferrite or the like, so that the isotropic sintered ferrite is used. Magnetic properties equivalent to those of magnets can be obtained. Utilizing the high degree of freedom of shape of the extremely anisotropic plastic ferrite, the engaged parts 2c, 2c consisting of square holes are easily formed in the inner wall 2b of the annular magnet 2 to form the axial engaging parts 1f, 1f. Can be engaged with the edge of the inner wall 2b. Since the rotary shaft 1 with gears is not simply insert-molded into the ring-shaped magnet 2 but is simply molded and fitted into the ring-shaped magnet 2, the processing cost can be reduced. The front ends of the two wing-shaped parts 1d are inserted into the engaged parts 2c, 2c made of square holes, and the axial engaging parts 1f, 1f are engaged with the edges of the inner wall 2b, so that Since the annular magnet 2 is engaged in the axial direction, the engagement is easy and the engagement is ensured. Since the two elastic pieces 1e, 1e formed on the rotating shaft 1 with gears are pressed against the inner circumference 2a of the annular magnet 2 to connect the rotating shaft 1 with gears and the annular magnet 2, the two elastic pieces 1e, 1e The rotation direction of the rotation prevention part 1g, which is composed of the notch, and the opening moment of 1g, and snap-fit engagement by frictional resistance with the opening moment of 1g, and concentricity can be easily obtained. Rotation direction detents 1g, 1g consisting of notches formed on the rotary shaft with gears 1 are engaged with the projection-like engaged parts 2e, 2e formed on the annular magnet 2 so that there is no play in the rotational direction. . Further, the ring magnet 2 can be injection-molded, and the rotary shaft 1 with gears is not an insert-molding but a simple molding, so that the cost can be reduced. Since the rotary shaft 1 with a gear and the annular magnet 2 are engaged with each other by a snap fit, the assembly is easy.

In the above description, the rotor of the small motor is described as the rotor of the permanent magnet type stepping motor, but the rotor of the permanent magnet type motor of other types may be used. .

[0013]

[Effect of the device]

 Since the present invention is configured as described above, the ring magnet can be injection-molded, and the rotary shaft with a gear is only simple molded instead of insert-molded, which allows cost reduction, and a snap-fit with a gear. Since the rotating shaft and the annular magnet are engaged, the assembling is easy, the concentricity is easily obtained, and the looseness in the rotating direction is eliminated. Further, it is possible to provide a small-sized motor rotor which is easily engaged in the axial direction and has excellent practical effects such as reliable engagement.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view of a main part of an annular magnet of a rotor of a small motor.

FIG. 2 is a front view of a rotor of a small motor.

FIG. 3A is a side view and FIG. 3B is a front view of a rotary shaft with gears.

4A is a sectional front view of an annular magnet, and FIG. 4B is a sectional view of FIG.
2 is a cross-sectional side view taken along line bb of FIG.

FIG. 5 is another side view of the rotary shaft with gears.

FIG. 6 is a cross-sectional side view taken along the line aa of FIG.

[Explanation of symbols]

 1 Rotating shaft with gear 1e Elastic piece 1f Axial engagement part 1g Rotation direction detent part 1h Shaft centering part 1i Gear 2 Ring magnet 2a Inner circumference 2c Engagement part 2d Tube part 2e Engagement part

Claims (1)

[Scope of utility model registration request] 1. A rotor for a small-sized motor comprising a rotating shaft with a gear and an annular magnet, wherein the rotating shaft is made of synthetic resin, and an elastic piece press-contacting the inner circumference of the annular magnet and the shaft with the magnet. Direction engaging portion, rotation preventing portion for rotation with magnet, axial centering portion, annular magnet is synthetic resin magnet, engaged portion engaging with the axial engaging portion, A rotor for a small motor having an engaged portion that engages with a stopper portion and a tubular portion into which the centering portion fits, and has a rotary shaft and an annular magnet fitted and integrated.