JP2002051523A - Stepping motor and rotor thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stepping motor and a rotor thereof capable of easy assembly with a simple structure. SOLUTION: This stepping motor 10 comprises a rotor 20 and a stator 11. The rotor consists of a hollow cylindrical rotor magnet 21 of which one end in the axial direction is closed, a bush 22 attached at an open end of the rotor magnet, and a rotating shaft 23 fixed and supported in the bush and the center of the closed end of the rotor magnet. The stator consists of bearings 12, 13 rotatably supporting the rotating shaft of the rotor, and coils 15 displaced so as to face the rotor magnet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor and its rotor, and more particularly to a structure for supporting a rotor magnet and a rotating shaft of the rotor.

[0002]

2. Description of the Related Art Conventionally, a stepping motor is configured as shown in FIG. That is, in FIG.
The stepping motor 1 includes a stator 2 and a rotor 5 rotatably supported by bearings 3 and 4.

[0003] The stator 2 includes a yoke 2a and a coil 2b.
And a flange 2c that supports the bearings 3 and 4 and a case 2d that surrounds the whole. The yoke 2a is formed so as to extend outward in the axial direction so as to face the coil 2b so as to sandwich the coil 2b from both sides in the axial direction.

On the other hand, as shown in FIG. 4, a rotor 5 has a hollow cylindrical rotor magnet 5a and bushes 5b and 5c mounted in the rotor magnet 5a.
And a rotating shaft 5d attached to the bushes 5b and 5c.
And is composed of

The rotor magnet 5a is open at both ends, is constituted by a permanent magnet, and is appropriately magnetized in the circumferential direction. The bushes 5b and 5c are composed of two disks, and have outer peripheral edges 5e and 5f.
Abuts on the inner wall surface of the hollow portion of the rotor magnet 5a and is fixed by bonding, and has a rotation shaft 5d at the center.
Are provided with central holes 5g and 5h for mounting the same.

The rotating shaft 5d is connected to the bushes 5b, 5b.
c is inserted into the central holes 5g and 5h by press fitting or the like, is fixed and held, and has a driving gear 6 at one end. Further, when the rotating shaft 5d is mounted on the bearings 3 and 4 supported by the flange 2c of the stator 2 and the case 2d, a resin as a spacer is provided on the bearing 3 side so as not to move along the axial direction. Washer 7
On the bearing 4 side, two resin washers 8a, 8
b and a spring washer 8c between them are interposed.

According to the stepping motor 1 configured as described above, when a current flows through the coil 2 b of the stator 2, the magnetic field generated in the coil 2 b mutually interacts with the magnetic field of the rotor magnet 5 a via the yoke 2 a. As a result, the rotor 5 is driven to rotate.

[0008]

By the way, in the stepping motor 1 having such a structure, when assembling the rotor 5, the rotating shaft 5d is first press-fitted into the center holes 5g, 5h of the bushes 5b, 5c. And so on. Thereafter, the outer peripheral edges 5e, 5f of the bushes 5b, 5c are fixed to the inner wall surface of the rotor magnet 5a by bonding or the like. The rotor 5 thus assembled is pivotally supported at both ends of the rotating shaft 5d by bearings 3 and 4 via resin washers 7, 8a and 8b and spring washers 8c, and the stepping motor 1 is completed.

Therefore, the rotating shaft 5d is connected to the rotor magnet 5
The bush 5b, 5c is required to be attached to the center of a, and these bushes 5b, 5c are attached to the inner wall surface of the rotor magnet 5a by bonding. Further, in order to suppress the axial movement of the rotating shaft 5d of the rotor 5, on the bearings 3 and 4 side, a resin washer 7 as a spacer and a resin washer 8 respectively.
a, 8b and a spring washer 8c are required. For this reason, there are problems that the number of parts increases, the assembling work becomes complicated, and the parts cost and the assembling cost increase.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a stepping motor and a rotor thereof that can be easily assembled with a simple configuration.

[0011]

According to the present invention, there is provided a hollow cylindrical rotor magnet (21) having one end closed in the axial direction, and a bush (21) attached to an open end of the rotor magnet (21). 22) and this bush (2
2) and a rotating shaft (23) fixedly held at the center of the closed end of the rotor magnet (21).
0), bearings (12) and (13) for rotatably supporting the rotation shaft (23) of the rotor (20), and a yoke (1) arranged to face the rotor magnet (21).
4) and a coil (15).
This is achieved by a stepping motor (10), characterized in that it includes:

According to the present invention, there is provided a hollow cylindrical rotor magnet (2) having one end closed in the axial direction.
1), a bush (22) attached to the open end of the rotor magnet (21), and a rotating shaft (23) fixedly held at the center of the bush (22) and the closed end of the rotor magnet (21). This is achieved by the rotor (20) of the stepping motor (10), characterized in that it comprises:

A stepping motor (10) according to the present invention.
And the rotor (20) preferably has an extension (21) in which the closed end of the rotor magnet (21) extends outwardly around its center so as to surround the rotation axis (23).
b), the end face (21) of this extension (21b).
c) is in sliding contact with the end face of one of the bearings (12).

According to the above configuration, since only one bush (22) holds the rotating shaft (23) of the rotor (20), the number of parts is small and the bush (2
Since the outer peripheral edge of 2) is directly adhered and fixed to the inner wall surface of the rotor magnet (21), assembly can be easily performed with a simple configuration. Therefore, component costs and assembly costs can be reduced.

The closed end of the rotor magnet (21) is provided with an extension (21b) extending outward so as to surround the rotating shaft (23) near the center thereof. The end face (21c) is connected to one of the bearings (12).
When sliding on the end face, the end face (21c) of the extension (21b) slides on the end face of the bearing (12), whereby the rotor magnet (21) is positioned in the axial direction, and the axial movement is suppressed. Will be done. Therefore, an axial positioning member such as a resin bush in the conventional stepping motor (10) is not required, the number of parts is reduced, and the parts cost and the assembly cost can be further reduced. It should be noted that the reference numerals in the parentheses are provided for easy understanding, are merely examples, and the present invention is not limited to these.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. FIG. 1 shows a configuration of an embodiment of a stepping motor according to the present invention. In FIG. 1, a stepping motor 10 includes a stator 11 and a rotor 20 rotatably supported by bearings 12 and 13.

The stator 11 includes a yoke 14 and a coil 1.
5 and a flange 16 for supporting the bearings 12, 13 and a case 17 for surrounding the whole. The yoke 14 is formed so as to face outward so as to sandwich the coil 15 from both sides in the axial direction by extending outward in the axial direction.

On the other hand, as shown in FIG. 2, the rotor 20 has a hollow cylindrical rotor magnet 21, a bush 22 mounted in the rotor magnet 21, and a rotating magnet arranged at the center of the rotor magnet 21. Axis 23,
It is composed of

The rotor magnet 21 has one end (the left end in FIG. 2) in the axial direction closed and the other end (the right end in FIG. 2) opened, and is constituted by a permanent magnet, and is appropriately formed in the circumferential direction. It is magnetized. The rotor magnet 21 has a center hole 21a at the center of the closed end for mounting the rotating shaft 23.

The bush 22 is formed of a single disk, and its outer peripheral edge 22a abuts on the inner wall surface near the open end of the rotor magnet 21 and is fixed by bonding, and rotates around the center. A center hole 22b for attaching the shaft 23 is provided.

The rotary shaft 23 is provided at the closed end of the rotor magnet 21 and the center holes 21a and 22b of the bush 22.
It is inserted into the inside by press fitting or the like, is fixed and held, and has a driving gear 24 at one end.

Further, the rotating shaft 23 is
Bearings 12 supported by a flange 16 and a case 17 of
13, the rotor magnet 21 is provided on the bearing 12 side so that the rotor magnet 21 does not move along the axial direction.
An extension 21b protruding outward (to the left in FIG. 2) so as to surround the rotation shaft 23 near the center of the closed end.
It has. On the bearing 13 side, the rotating shaft 2
3 is provided with two resin washers 25a and 25b and a spring washer 26 therebetween.

The bush 22 is made of, for example, iron or aluminum. In the case of iron, the cost can be reduced, and in the case of aluminum, a non-magnetic material is used. Influence can be suppressed. The bush 22 has a step 22c on the outer peripheral edge 22a. This step 2
2c can be formed by, for example, pressing at the same time when the bush 22 is punched. This allows
When the bush 22 is attached to the inner wall surface of the rotor magnet 21 with an adhesive, the adhesive collects over the entire circumference in the space defined by the step 22c and the inner wall surface of the rotor magnet 21. . By hardening the adhesive pool, the bush 22 can be more securely bonded and fixed to the rotor magnet 21.

Further, the bush 22 has a central hole 22.
and a rising portion 22d extending in the axial direction from b. The rising portion 22d is formed by, for example, a parling process. As a result, the holding strength of the bush 22 with respect to the rotating shaft 23 is increased. When the thickness of the disk constituting the bush 22 is, for example, 1.5 mm or more and the bush 22 is relatively thick, the rising portion 22c may be omitted.

Further, the bush 22 has a thermal expansion absorbing hole 22e in a part thereof. Although only one thermal expansion absorption hole 22e is shown in the drawing, the position and number thereof can be set arbitrarily within a range that does not decrease the strength of the disk constituting the bush 22, In the vicinity of the outer periphery, an adhesive may adhere when the bush 22 is bonded to the inner wall surface of the rotor magnet 21, or the inertia with respect to the center of the bush 22 may change. It will be located nearby.

The stepping motor 10 according to the embodiment of the present invention is configured as described above.
It is assembled as follows. First, the rotating shaft 23 is attached to the center hole 22b of the bush 22 by press fitting or the like. Subsequently, the rotating shaft 23 is attached to the center hole 21a at the closed end of the rotor magnet 21 by press fitting or the like. Then, the outer peripheral edge 22a of the bush 22 is fixed to the inner wall surface near the open end of the rotor magnet 21 by bonding or the like. At that time, the adhesive 27 accumulates in an annular space defined by the step 22 c provided on the outer peripheral edge 22 a of the bush 22 and the inner wall surface of the rotor magnet 21. Therefore, by curing the adhesive 27, the bush 22 can be securely bonded and fixed to the rotor magnet 21.

The rotor 20 assembled as described above
The two ends of the rotating shaft 23 are
The stepping motor 10 is completed by being pivotally supported by the motors 2 and 13. Thus, in the stepping motor 10, when a current flows through the coil 15 of the stator 11, the magnetic field generated in the coil 15 interacts with the magnetic field of the rotor magnet 21 via the yoke 14 to rotate the rotor 20. Will be done.

In this case, since only one bush 22 is provided and the outer peripheral edge 22a of the bush 22 is directly adhered and fixed to the inner wall surface of the rotor magnet 21, the number of parts is reduced, and assembly is facilitated. As can be done, component and assembly costs may be reduced. Here, since the rotating shaft 23 is supported at two points by only one bush 22 and the closed end of the rotor magnet 21, there is no possibility that the rotating shaft 23 will rotate and touch during rotation.

Further, an end surface 21c of an extension 21b extending outward from the vicinity of the center of the closed end of the rotor magnet 21
However, since the rotor magnet 21 and the rotary shaft 23 are positioned in the axial direction by sliding on the end face of the bearing 12, a spacer such as a resin bush for restricting the axial movement as in the related art is unnecessary. become. Therefore, the number of parts can be reduced, and parts costs and assembly costs can be reduced.

When the temperature rises during operation of the stepping motor 10 or the like, even if the bush 22 itself thermally expands, deformation due to thermal expansion can be prevented by the presence of the thermal expansion absorption hole 22e. Thus, cracks and the like of the rotor magnet 21 can be prevented.

In the above embodiment, the bush 22
Is composed of, for example, iron, but is not limited to this, and may be composed of other materials.If the material is appropriately adjusted, for example, if the inertia is increased, for example, Shinchu, or if the inertia is decreased, , Aluminum, etc., or by appropriately selecting the plate thickness,
The inertia adjustment of the bush 22 and the rotor 20 can be performed.

[0032]

As described above, according to the present invention, since only one bush holds the rotating shaft of the rotor, the number of parts is reduced, and the outer peripheral edge of the bush is directly connected to the rotor. Since it is adhesively fixed to the inner wall surface of the magnet, assembly can be easily performed with a simple configuration. Therefore, component costs and assembly costs can be reduced.

In the vicinity of the center of the closed end of the rotor magnet, there is provided an extension extending outward so as to surround the rotating shaft, and when the end face of this extension comes into sliding contact with one of the bearing end faces, When the end face of the extension portion comes into sliding contact with the bearing end face, the rotor magnet is positioned in the axial direction. Therefore, an axial positioning member such as a resin bush in the conventional stepping motor is not required, the number of components is reduced, and the component cost and the assembly cost can be further reduced.

Thus, according to the present invention, it is possible to provide an extremely excellent stepping motor and its rotor which can be easily assembled with a simple structure.

[Brief description of the drawings]

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

FIG. 2 is a schematic sectional view showing a configuration of a rotor in the stepping motor of FIG.

FIG. 3 is a schematic sectional view showing a configuration of an example of a conventional stepping motor.

FIG. 4 is a schematic sectional view of a rotor in the stepping motor of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Stepping motor 11 Stator 12, 13 Bearing 14 Yoke 15 Coil 16 Flange 17 Case 20 Rotor 21 Rotor magnet 21a, 22b Center hole 21b Extension 21c End face 22 Bush 22a Outer rim 22c Step 22d Rise 23 Rotary shaft 24 Drive gear 25 , 25b Resin washer 26 Spring washer 27 Adhesive

Claims (4)

[Claims] 1. A hollow cylindrical rotor magnet whose one end in the axial direction is closed, a bush attached to an open end of the rotor magnet, a rotary shaft fixedly held at the center of the bush and the closed end of the rotor magnet, A stator comprising: a rotor configured to rotatably support a rotating shaft of the rotor; and a yoke and a coil disposed to face the rotor magnet. Stepping motor. 2. A closed end of the rotor magnet is provided with an extension extending in the vicinity of the center so as to surround the rotating shaft, and the end face of the extension slides on one bearing end face. The stepping motor according to claim 1, wherein: 3. A hollow cylindrical rotor magnet whose one end in the axial direction is closed, a bush attached to the open end of the rotor magnet, a rotary shaft fixedly held at the center of the bush and the closed end of the rotor magnet, A rotor for a stepping motor, comprising: 4. The stepping motor according to claim 3, wherein the closed end of the rotor magnet has an extension protruding outward so as to surround a rotation axis near a center thereof. Rotor.