JPH0638416A - Fixing structure for rotor magnet - Google Patents

Abstract

PURPOSE:To obtain a rotor magnet fixing structure which can easily and accurately mount a rotor magnet on a main shaft and, at the same time, can prevent the occurrence of vibrations between the main shaft and rotor magnet. CONSTITUTION:A cylindrical rotor magnet 12 is mounted on and fixed to a main shaft 10 while ring-shaped metallic bodies 14 and 16 respectively having inside diameters D3 and D4 which are equal to the outside diameter D1 of the shaft 10 are coaxially fixed to both end sections of the magnet 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor magnet fixing structure for fixing a rotor magnet of a small stepping motor to a main shaft.

[0002]

2. Description of the Related Art As a stepping motor using a permanent magnet (rotor magnet) for a rotor, there is, for example, one shown in FIG. In this stepping motor, a cylindrical rotor magnet 4 is attached to the outer circumference of the main shaft 2, and the outer circumference of the rotor magnet 4 is covered.
The stator 5 is arranged and configured.

Inside the stator 5, coils 6 and 8 for exciting the magnetic poles of the stator 5 are arranged. Further, the rotor magnet 4 is magnetized so that the S pole portions 4a and the N pole portions 4b formed along the axial direction are alternately arranged on the outer circumference in the circumferential direction.

The cylindrical rotor magnet as shown in the above stepping motor is generally manufactured by sintering. At the time of this sintering molding, in consideration of fixing to the main shaft, the inner diameter portion into which the main shaft is inserted is manufactured so that the inner diameter thereof is slightly larger than the outer diameter of the main shaft. And
When fixing the rotor magnet to the main shaft, the main shaft is passed through the inner diameter portion of the rotor magnet, then positioned, and both are integrally fixed by an adhesive applied between the main shaft and the rotor magnet. It is like this.

In the case of the rotor magnet fixing structure as described above, the workability when fixing the rotor magnet is poor,
It was desired to improve this. Further, in the small stepping motor using the rotor magnet fixing structure as described above, there is a problem that vibration is likely to occur due to a minute gap generated between the main shaft and the rotor magnet, and noise is likely to occur. The present invention is intended to solve the above problems.

[0006]

DISCLOSURE OF THE INVENTION The present invention is a rotor magnet fixing structure for integrally fixing a sinter-molded cylindrical rotor magnet to a main shaft rotatably supported around an axis. At each end of the rotor magnet, a metal ring-shaped body having an inner diameter that is the same as the outer diameter of the spindle is fixed with the axis of the rotor magnet aligned, and in this state, with respect to the spindle. It is characterized by being fixed.

Further, when the two rotor magnets are axially connected to each other through the spacers, each of the end portions of the rotor magnets on the side without the spacer has the same inner diameter as the outer diameter of the main shaft. Fix the metal ring-shaped body with the rotor magnet and the axis line as one,
In this state, it may be fixed to the main shaft.

[0008]

In the fixing structure of the rotor magnet having the above structure, the metal ring-shaped body, which is easier to increase the accuracy of the inner diameter dimension than the rotor magnet, is fixed to the end portion of the rotor magnet. Since the rotor magnet is fixedly attached, the allowable inner diameter dimensional accuracy of the rotor magnet is relaxed as compared with the conventional one. That is, a rotor magnet (or two rotor magnets connected via a spacer)
Both ends of the ring are ring-shaped bodies with a high inner diameter accuracy, and since the inner diameters of these ring-shaped bodies are accurately fixed to the spindle, the inner diameter of the rotor magnet only needs to be able to be inserted through the spindle. Does not need The same applies to the inner diameter of the spacer. The ring-shaped body can be fixed on the basis of the outer peripheral shape of the rotor magnet.

Since the main shaft and the ring-shaped body are fitted with each other with almost no clearance, if an adhesive is applied to the outer periphery of the main shaft or the inner periphery of the ring-shaped body and the two are fitted together, positioning in the radial direction is not required unlike the conventional case. Immediately, the ring-shaped body is positioned on the spindle. Also, the coaxiality of the rotor magnet with respect to the main axis is improved.

Further, since the ring-shaped body is fixed to the main shaft without a gap, in the stepping motor using the fixing structure of the rotor magnet according to the present invention, noise caused by vibration between the rotor magnet and the main shaft is generated. Is prevented.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing a rotor magnet fixing structure according to an embodiment of the present invention.
Reference numeral 10 is a main shaft, and reference numeral 12 is a rotor magnet formed in a cylindrical shape.

The rotor magnet 12 is formed by sintering, and magnetized so that the S pole portions and the N pole portions formed along the axial direction are alternately arranged on the outer circumference of the rotor magnet 12. The point (not shown) is similar to the rotor magnet 4 shown in FIG.

At both ends of the rotor magnet 12, metal ring-shaped bodies 14 and 16 manufactured by pressing, machining or the like are fixed to the rotor magnet 12 with their axes aligned. These ring-shaped bodies 14, 16
Is accurately fixed (joined) to the rotor magnet 12 with reference to the outer diameter of the rotor magnet 12,
The inner diameters D3 and D4 are formed to be substantially the same as the outer diameter D1 of the main shaft 12.

The rotor magnet 12 and the ring-shaped bodies 14 and 16 are fixed to the main shaft 10 by joining the ring-shaped bodies 14 and 16 to both ends of the rotor magnet 12 and then to the outer periphery of the main shaft 10 or the ring-shaped body 14. , 16
It is carried out by applying an adhesive to the inner circumference of or both of them and then fitting them together.

According to the fixing structure of the rotor magnet having the above-mentioned structure, the metal ring-shaped bodies 14 and 1 whose inner diameter dimension can be more easily improved as compared with the rotor magnet 12.
Since 6 is fixed to each end of the rotor magnet 12 and fixed to the main shaft in this state, the allowable accuracy of the inner diameter dimension D2 of the rotor magnet 12 can be relaxed as compared with the conventional one. That is, the inner diameter portion of the rotor magnet 12 is
Since it is not used for radial positioning with respect to the rotor magnet 12, the inner diameter dimension D2 of the rotor magnet 12 may be formed to be slightly larger than the outer diameter D1 of the main shaft, and the accuracy is not required as in the conventional case.

Further, since the main shaft 10 and the ring-shaped bodies 14 and 16 are fitted with each other without a gap, there is no need for radial positioning work when the rotor magnet 12 is mounted on the main shaft 10, and workability is improved as compared with the prior art. Is significantly improved, and the coaxiality of the rotor magnet 12 with respect to the main shaft 10 is also improved.

In the stepping motor using the rotor magnet fixing structure as described above, since no vibration is generated between the main shaft and the rotor magnet, noise can be well prevented.

In the above-described embodiment, the metal ring-shaped body is fixed to both ends of one rotor magnet. For example, as shown in FIG. 2, they are connected in the axial direction via a spacer 18. Two rotor magnets 12
a and 12b, the ring-shaped bodies 14 and 1 similar to the above-mentioned embodiment
6 may be fixed. In this case, as shown in FIG. 2, the ring-shaped bodies 14, 1 are attached to the ends of the rotor magnets 12a, 12b on the side not contacting the spacer 18.
6 will be fixed.

With this structure, the same effect as that of the above embodiment can be obtained, and the tolerance of the inner diameter D5 of the spacer 18 can be relaxed.

[0020]

As described above, according to the present invention, the metal ring-shaped body, which is easier to increase the accuracy of the inner diameter than the rotor magnet, is fixed to the end portion of the rotor magnet. Since the rotor magnet is fixed to the main shaft, the allowable inner diameter dimensional accuracy of the rotor magnet can be relaxed compared to the conventional one, and the coaxiality of the rotor magnet with respect to the main shaft is improved. This eliminates the need for radial positioning work and significantly improves workability.

In the stepping motor using the rotor magnet fixing structure as described above, no vibration is generated between the main shaft and the rotor magnet, so that noise can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a rotor magnet fixing structure according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a rotor magnet fixing structure according to another embodiment of the present invention.

FIG. 3 is a side view showing a schematic configuration of a stepping motor.

[Explanation of symbols]

 10 Spindle 12, 12a, 12b Rotor magnet 14, 16 Ring-shaped body 18 Spacer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Inoue 1-297 Kitabukuro-cho, Omiya City, Saitama Prefecture Mitsubishi Materials Corporation, Mechatronics & Production System Development Center

Claims (2)

[Claims] 1. A rotor magnet fixing structure for integrally fixing a sinter-molded cylindrical rotor magnet to a main shaft rotatably supported around an axis, wherein each end of the rotor magnet is fixed. In the portion, a metal ring-shaped body having an inner diameter equal to the outer diameter of the main shaft is fixed to the rotor magnet with its axis line aligned, and in this state, is fixed to the main shaft. A fixed structure for the rotor magnet. 2. A rotor magnet fixing structure for integrally fixing a sintered rotor cylindrical cylindrical magnet to a main shaft rotatably supported around an axis, wherein the rotor magnet is a spacer. Are connected in the axial direction via a rotor, and a metal ring-shaped body having an inner diameter equal to the outer diameter of the main shaft is provided at each end of the rotor magnet on the side without the spacer. A fixed structure for a rotor magnet, characterized in that it is fixed to the main shaft in this state.