JP2002176760A - Stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve rotational accuracy by restraining dimensional variations in the rotational-axis direction (thrust direction) of a small-sized stepping motor. SOLUTION: This stepping motor is formed in a cylindrical form, has a rotor circumferentially divided into (n) portions and alternately polarized with different poles. A first coil, the rotor and a second coil are disposed in the order thereof in the axial direction of the rotor so that one end of the rotor may be sandwiched with first outer and inner poles excited by the first coil facing an outer-periphery surface and an inner-periphery surface of one end of the rotor, and the other end of the rotor may be sandwiched with second outer and inner poles excited by the second coil facing the outer-periphery surface and the inner-periphery surface of the other end of the rotor. This motor also includes a connecting ring engaged and connected with the first outer pole and the second outer pole at the inner-periphery surface, and a projecting part for contacting with the end surface of the connecting ring, formed at the first outer pole and the second outer pole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a small motor.

[0002]

2. Description of the Related Art Conventional small cylindrical motors include:
As described in JP-A-10-075558,
It is configured as shown in FIG.

[0003] In FIG. 4, reference numeral 1 denotes a hollow cylindrical permanent magnet constituting a rotor. The permanent magnet 1 has an S pole and an N pole alternately magnetized. Reference numeral 2 denotes a rotating shaft serving as a rotor shaft.
The rotating shaft 2 is fixed to the permanent magnet 1 by press fitting or the like. The rotating shaft 2 and the permanent magnet 1 constitute a rotor. Reference numerals 3 and 4 denote cylindrical coils. The coils 3 and 4 are arranged concentrically with the permanent magnet 1 and at positions sandwiching the permanent magnet 1 in the axial direction. It is almost the same size as the diameter. Reference numerals 18 and 19 denote a first stator and a second stator made of a soft magnetic material.
Is composed of an outer cylinder and an inner cylinder. The rotating shaft 2 is rotatably fitted into the hole 18 e of the stator 18 and the hole 19 e of the stator 19.

[0004] Reference numeral 10 denotes a cylindrical connecting ring made of a non-magnetic material.
0a, 10b are provided, and grooves 10a, 10b are provided on the other end side.
Grooves 10c and 10d are provided with phases shifted from each other by 45 degrees, the outer magnetic poles 18a and 18b of the first stator 18 are fitted into the grooves 10a and 10b, and the outer magnetic poles of the second stator 19 are fitted into the grooves 10c and 10d. The magnetic poles 19a and 19b are fitted, and these fitting portions are fixed by bonding or the like, and the stators 18 and 19 are attached to the connecting ring 10. At this time, the stators 18 and 19 have outer magnetic poles 18a, 18b and 19a,
19b and the protrusion 10 on the inner surface of the connection ring 10
e, are fixed by the connecting ring 10 at a distance of 10f.

[0005]

However, in the above-mentioned conventional example, the axial dimension (thrust dimension) of the stator is determined by the tip position of the outer magnetic pole of the stator and the width of the inner projection of the connecting ring. However, there has been a problem that the thrust dimension varies when the stator is deformed such as falling down during assembly. In addition, since it is a method of hitting the protruding portion on the inner surface side of the connecting ring, it cannot be confirmed whether the contact has been reliably made at the time of assembly, and it has been difficult to establish a reliable assembly process. Further, when the thrust dimension is increased, there is a disadvantage that the variation in the thrust direction of the rotating shaft is increased. Further, when the thrust dimension is reduced, the rotating shaft comes into contact with the stator, and the rotation is not smooth. In the worst case, the rotation cannot be performed.

[0006] Accordingly, it is an object of the present invention to suppress variation in the thrust dimension and improve the rotational accuracy of the motor. It is another object of the present invention to enable stable assembly, increase production efficiency, and reduce the rate of defective products.

[0007]

In order to achieve the above object, a motor according to the present invention has a first outer magnetic pole and a second outer magnetic pole provided with a convex portion which comes into contact with an end face of a connecting ring. .

[0008] In the above configuration, the first outer magnetic pole and the second outer magnetic pole are respectively formed by convex portions provided thereon.
The end surface of the connection ring can be contacted. Thereby, the first
It is easy to keep the thrust dimensions of the stator and the second stator constant, and a motor with high rotation accuracy can be obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a drawing which best illustrates the features of the present invention. Reference numeral 18 denotes a first stator excited by the first coil 3, and 19 denotes a second stator excited by the second coil 4. The first coil 3 is inserted between the inner magnetic pole and the outer magnetic pole of the first stator 18, and then one of the rotating shafts 2 to which the permanent magnet 1 is fixed can be rotated into the hole 18 e of the first stator 18. Insert

In this state, a cylindrical connecting ring 1 is provided.
0 is pressed and inserted in the radial direction. At this time, one ends 10g and 10h of the connection ring abut on the protrusions 18g and 18h provided on the outer peripheral portion of the first stator 18, and the positions of the first stator 18 and the connection ring 10 in the thrust direction are changed. It is determined.

Next, the other of the rotating shaft 2 is already
While being inserted into the hole 19e of the second stator 19 in which is inserted, is further press-fitted and inserted into the connecting ring 10. The second stator 19 has convex portions 19g and 19h provided on the outer periphery.
Abuts on the other ends 10i, 10j of the connecting ring 10 and is positioned.

At this time, the shape of the convex portion of the stator is shown in FIGS.
Shown in The shape shown in FIG. 2 is an example in which the stator is formed by bending after forming the outer shape by pressing or the like, and the protrusion is formed so as to protrude from the outer periphery of the stator by bending. As a result, a stable convex portion can be formed in one processing step.

FIG. 3 shows an example in which a convex portion is formed by extruding (half blanking) with a press or the like. When the material thickness of the outer magnetic pole is large, the above-mentioned bending may be difficult,
At that time, the shape becomes effective. Of course, the convex portion may be formed by another method (such as burring).

As described above, the positioning of the stators 18 and 19 in the thrust direction is performed. Then, the connecting ring 10
And the stators 18 and 19 are fixed by bonding, laser welding, etc., respectively, thereby completing the motor.

[0015]

As described above, according to the present invention,
By providing the outer peripheral portions of the first outer magnetic pole and the second outer magnetic pole with the convex portions that come into contact with the end faces of the connection ring, the thrust dimension of the motor can be stabilized. As a result, the position of the rotor in the thrust direction with respect to the first and second stators is stabilized, so that the motor has high rotation accuracy. Furthermore, since the abutting state of the connecting ring and the stator can be confirmed after the assembly, it is not necessary to confirm the dimensions after the assembly, and the production efficiency in the assembly process can be improved. Further, the occurrence rate of defective products can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a motor according to an embodiment of the present invention.

FIG. 2 is a perspective view of an example showing a shape of a stator of the motor according to the embodiment of the present invention.

FIG. 3 is a perspective view of another example showing the shape of the stator of the motor according to the embodiment of the present invention.

FIG. 4 is a sectional view showing a conventional motor.

[Explanation of symbols]

 Reference Signs List 1 permanent magnet rotor 2 rotating shaft 3 coil 4 coil 10 connecting ring 10g, 10h, 10I, 10j connecting ring end face 18 first stator 18a, 18b outer magnetic pole 18c, 18d inner magnetic pole 18c, 18d convex part of outer magnetic pole 19th 2 stators 19a, 19b Outer magnetic poles 19c, 19d Inner magnetic poles 19c, 19d Projections of outer magnetic poles

Claims (3)

[Claims] A rotor having a cylindrical shape, divided into n portions in a circumferential direction and alternately magnetized to different poles;
A first coil, the rotor, and a second coil are sequentially arranged in the axial direction of the rotor, and a first outer magnetic pole and a first inner magnetic pole excited by the first coil are arranged on the outer periphery of one end of the rotor. A second outer magnetic pole and a second inner magnetic pole which are excited by a second coil and which have an outer peripheral surface and an inner peripheral surface on the other end side of the rotor, while sandwiching one end of the rotor so as to face the surface and the inner peripheral surface. A first outer magnetic pole, wherein the first outer magnetic pole is connected to the first outer magnetic pole and the second outer magnetic pole by an inner peripheral surface. And a second outer magnetic pole having a projection for abutting an end face of the connection ring. 2. The motor according to claim 1, wherein the projections of the first and second outer magnetic poles are formed by bending. 3. The motor according to claim 1, wherein the projections of the first and second outer magnetic poles are formed by half blanking.