JP3503794B2 - motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor having a structure in which a ball bearing is used as a bearing for supporting a rotor shaft at both ends, even when the rotor is displaced with respect to the ball bearing. The present invention relates to a motor whose center alignment with and is automatically adjusted.

[0002]

2. Description of the Related Art Conventionally, an oil-impregnated bearing has been mainly used as a bearing for supporting a rotor shaft in a motor. This oil-impregnated bearing is a bearing in which a bearing member made of porous sintered metal is impregnated with lubricating oil, and a part of the lubricating oil impregnated inside during operation of the motor forms an oil film on the inner surface of the bearing. By making it, the lubrication of the shaft supporting portion rotating at high speed is ensured. By the way, since the oil film in such an oil-impregnated bearing is consumed over time, the lubricant is supplied from the inside of the bearing to the inner surface of the bearing due to the capillary phenomenon of the porous portion. Therefore, the life of the oil-impregnated bearing is proportional to the amount of the impregnated lubricating oil. Therefore, when a long-life motor is required, the bearing volume must be increased. As a result, there is a drawback that the motor also becomes large.

In addition, in the motor using the oil-impregnated bearing of this kind, although the life of tens of thousands of hours can theoretically be secured, the life of the motor actually expires in the thousands of hours. The reality is The cause is that when some external force is applied to the motor and the rotor is displaced with respect to the bearing, the contact point between the bearing and the rotor shaft is deflected and the contact pressure increases locally, so that lubrication at that part occurs. It is thought that the oil will be consumed more heavily.

Therefore, conventionally, as a motor which is required to be stably driven for a particularly long period of time, even if a displacement that causes misalignment occurs between the bearing and the rotor shaft due to the structure, if it is a slight displacement, It has become possible to manufacture a motor using a ball bearing as a bearing, which is capable of absorbing heat and maintaining the lubricating characteristics for a long period of time without holding a large amount of lubricating oil. FIG. 3 shows an example of a conventional motor using a ball bearing as such a bearing. This motor is a rotor 1
A stator 2 for rotatably housing the rotor 1 with a gap inside, and a stator 2 for housing the rotor 1
Of the mounting plates 3 and 4 mounted so as to close both ends of the.

The rotor 1 is a cylindrical rotationally symmetric body with the shaft 5 as a center, and a permanent magnet is fixed to the periphery thereof, and the outer peripheral surface is magnetized by a plurality of magnets. There is. Further, the stator 2 is composed of two stator parts, that is, a first stator part 6 and a second stator part 7. Here, the first stator portion 6 includes a bobbin 9 around which the ring-shaped coil 8 is wound, and a pair of yokes 10 arranged on both sides of the bobbin 9.
And each of the above-mentioned yokes 1 on the inner peripheral surface.
A plurality of pole teeth formed on the inner peripheral surface of 0 and 11 are alternately arranged at equal intervals. Similarly, the second stator portion 7
A bobbin 13 around which the ring-shaped coil 12 is wound, and a pair of yokes 14 arranged on both sides of the bobbin 13.
And each of the yokes 14 and 1 on the inner peripheral surface.
A plurality of pole teeth formed on the inner peripheral surface of the electrode 5 are alternately arranged at equal intervals. Then, the pair of yokes 10 and 11 described above.
And 14, 14 and 15 are press-fitted so as to be integrated, and the stator 2 is a cylindrical integral body.

The mounting plates 3 and 4 are metallic disk-shaped members having bearing recesses 3a and 4a formed in the central portions thereof, and close the openings of the cylindrical stator 2 respectively. It is fixed by welding. Ball bearings 16 and 17 are stored in the bearing storage portions 3a and 4a of the mounting plates 3 and 4, respectively.
Fixed, these ball bearings 16 and 1
The shaft 5 of the rotor 1 is inserted in 7. Reference numeral 18 in the figure is a plug terminal for supplying a current to the stator 2 from an external power supply.

Incidentally, in the motor having the above structure, the side circumference of the stator 2 is exposed. In addition to this, the stator is housed in a bottomed cylindrical case having a bearing housing recess at the bottom, and the opening is formed. There is also a motor in which a portion is closed by a mounting plate, and in a motor having a structure using the case, in FIG. 3, for example, one mounting plate 4 is replaced with a cylindrical case, and an opening portion of this case is used. The rest of the configuration is the same, except that the other mounting plate 3 is fixed. A motor having a structure in which a pair of mounting plates are fixed to the stator as shown in FIG. 3 and a motor having a structure in which the stator is housed in a cylindrical case and the mounting plates are fixed in the remaining openings are intended. It is used properly according to.

[0008]

In the stepping motor having the above structure, the ball bearings 16 and 1 are used as the bearings.
Since 7 is used, even when displacement occurs between the shaft 5 of the rotor 1 and other members including the ball bearings 16 and 17, the alignment is better than that of a motor in which the bearing is an oil-impregnated bearing. Easy to take These are ball bearings 16 and 1
This is because, when a displacement force is applied to 7, the strain can be absorbed between the ball and its casing structurally.

However, the amount of strain absorption of such a ball bearing is very small because it is limited within the range of the amount of displacement between the ball and the casing, and, as a result, the balls inside the bearing and the casing are absorbed. The contact life of the bearings is shortened because the contact of the bearings becomes uneven. Especially in the motor shown in FIG.
Since the stator 2 is divided and the fixing between the one mounting plate 3 and the stator 2 and the fixing between the stator 2 and the other mounting plate 4 are performed by welding, the rotor cannot be assembled. 5 shafts and ball bearings 1
6 and 17, a relatively large displacement is likely to occur, resulting in misalignment of the shaft 5 to deteriorate the characteristics of the motor and shorten its life.

The present invention has been made to effectively solve the problems of the conventional motors described above. Even when a displacement force that induces eccentricity is generated between the rotor shaft and the ball bearing, the present invention is automatically performed. It is an object of the present invention to provide a motor that can be aligned and that does not sacrifice compactness and economy.

[0011]

According to a first aspect of the present invention, there is provided a motor, a rotor, a stator that rotatably accommodates the rotor with a gap inside, and both ends of the stator that accommodates the rotor. And a pair of mounting plates mounted so as to close the respective openings of the both ends, and ball bearings for rotatably supporting the shaft of the rotor are fixed to the respective mounting plates. A motor in which an alignment member is provided around a pole bearing, wherein the alignment member is one of the ball bearings.
A molded body continuously over the entire circumference of the ring, and an inner surface in contact with said one of the ball bearings <br/> the alignment member, the ball bearings phosphorus along the axial direction of the rotor
By forming a curved surface projecting toward the ball bearing side over the entire circumference of the groove, the centering member supports the ball bearing by line contact along the circumferential direction at the center of the inner surface. It is what

According to a second aspect of the present invention, there is provided a motor having a rotor, a stator for rotatably accommodating the rotor with a gap therein, and a bottomed cylindrical shape for accommodating the stator accommodating the rotor therein. A case and a mounting plate that closes an opening of a bottomed cylindrical case that houses the stator therein, and one ball bearing that pivotally supports the shaft of the rotor is fixed to the bottom of the case. At the same time, the other ball bearing that axially supports the shaft of the rotor is fixed to the attachment plate, and a centering member is provided around at least one of the pole bearings. The alignment member is on one side
Integral molding continuously over the entire circumference of the ball bearing
A body, and an inner surface in contact with said one of the ball bearings of said alignment member, along the axial direction of the rotor above
By forming a curved surface projecting to the ball bearing side over the entire circumference of the ball bearing ,
At the center of the surface, the aligning member has a line contact along the circumferential direction.
The ball bearing is supported by touch .

A motor according to a third aspect is the motor according to the first or second aspect, wherein the aligning member is formed of synthetic resin.

In the motors according to claims 1 and 2, at least one of the ball bearings is supported by the aligning member fixed to the mounting plate, and the inner surface of the aligning member that contacts the ball bearing is fixed. By forming a curved surface that protrudes toward the ball bearing side along the axial direction of the rotor, the ball bearing is supported by line contact over the entire circumference of the ball bearing at approximately the center of the inner surface of the aligning member. Therefore, when the rotor shaft is tilted from the normal axial position with respect to the mounting plate and the stator, the ball bearing is also displaced along the inner curved surface of the centering member while maintaining the above contact state. It is possible to Therefore, even when the relative displacement between the mounting plate or the stator and the rotor shaft occurs, the ball bearing can be displaced with respect to the mounting plate in accordance with the displacement of the shaft, and thus the shaft and the ball bearing can be aligned. It can be done automatically. in addition,
Since the centering member supports the substantially central portion of the outer periphery of the ball bearing, an eccentric force does not act on the ball bearing. Therefore, the centering member automatically aligns the rotor shaft. Coupled with what can be done, the service life of the motor can be significantly extended.

In this case, in particular, in the motor according to claim 1, since the stator is not protected and held by the casing covering the whole, the stator according to claim 2 is protected and held by the case. The motor is more susceptible to the eccentric action due to the external force, so that a more remarkable effect can be obtained. Further, in the motor according to the second aspect, the reliability and the life of the motor can be further improved.

Further, since the aligning member is formed of an integrally molded body which is continuous over the entire circumference, the bearing can be supported uniformly, and therefore the bearing can be displaced evenly with respect to the mounting plate. With
The effect that installation work such as arrangement is easy is obtained.

Further, in the motor according to the third aspect , since the aligning member made of synthetic resin is used, the aligning member is more elastically deformable than other materials such as metal, and therefore, The variability of the ball bearing provided by the inner curved surface of the aligning member and the elastic deformability can be further enhanced.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a motor according to the present invention. The same components as those of the conventional motor shown in FIG. Turn into. In the motor of this embodiment, one mounting plate 20
The inner diameter of the bearing accommodating recess 20a is set to be larger than the conventional one, and the ball bearing 1 accommodated in the recess 20a is
The centering member 21 is interposed between the centering member 6 and the centering member 6. The aligning member 21 is a ring-shaped member integrally formed of a synthetic resin having an elastic deformation force such as polycarbonate resin, urethane resin, nylon resin, Teflon resin, and having a small friction coefficient with metal. Here, the inner surface 22 of the aligning member 21 is formed by a curved surface which is most inwardly directed toward the inside. The curved surface is formed into an arc in a sectional view, and the ball bearing 16 and the aligning member 21 are in contact with each other on the inner surface 22 thereof along a line continuous in the circumferential direction.

In the motor having the above structure, the inner curved surface 22 of the aligning member 21 bulges inward, and the center thereof bulges most, so that as shown in FIG. When the aligning member 21 of is cut along the diameter,
The inner curved surfaces facing each other are such that the central portions thereof are closest to each other and are gradually separated from each other toward both opening end portions. Therefore, as shown in FIG. 2, when an external force acts on the ball bearing 16 in a direction intersecting with the axis of the aligning member 21, the ball bearing 16 and the inner curved surface 22 of the aligning member 21 are aligned with each other. It is possible to easily incline with respect to the centering member 21 while maintaining contact, and as a result, the ball bearing 16 can easily incline with respect to the centering member 21.

Moreover, since the centering member 21 supports the substantially central portion of the outer periphery of the ball bearing 16, an eccentric force does not act on the ball from the casing of the ball bearing 16, thus The centering member 21 allows the rotor shaft 5 to be automatically centered, and the service life of the motor can be significantly extended. In addition, the aligning member 21
Since it is made of synthetic resin, it has less frictional resistance with the metal ball bearing 16 and can be elastically deformed, so that the ball bearing 16 can be more easily tilted. As a result, even if the rotor shaft 5 is largely eccentric with respect to the mounting plate 20 and the stator 2, misalignment between the ball bearing 16 and the rotor shaft 5 does not occur.

In the description of the above embodiment,
Although only the case where only one ball bearing 16 is supported by the aligning member 21 has been described, the present invention is not limited to this, and the other ball bearing 17 is provided.
At the same time, they may be supported by the aligning member. Also,
In this embodiment, the mounting plates 20 are provided in both openings of the stator 2.
Although the case where the present invention is applied to a motor having a simple structure in which (4) and (4) are attached is shown, the present invention can be similarly applied to a motor having a structure in which the stator is housed in a case and relatively strong against external force.

[0022]

As described above, in the motor according to the present invention, at least one ball bearing is fixed to the mounting plate over the entire circumference of the ball bearing.
Is supported by aligning members integrally molded contiguous Te, and the inner surface in contact with the ball bearing of the centering member is formed by a curved surface convex toward the ball bearing side along the axial direction of the rotor, ball bearings, the entire Passed around
Since it is supported in line contact with the inner surface of the centering member, even if the rotor shaft is tilted from the normal axial position with respect to the mounting plate and the stator, the ball bearings are also wholly corresponding. Since it can be easily tilted in the same direction, the shaft and the ball bearing can be automatically aligned, and the centering member supports the substantially central portion of the outer periphery of the ball bearing. Since no eccentric force acts on the ball bearing, the service life of the motor can be significantly extended as a result.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a motor according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a main part showing a displacement state of a ball bearing with respect to an alignment member in the motor of FIG.

FIG. 3 is a cross-sectional configuration diagram showing an example of a conventional motor.

[Explanation of symbols]

1 rotor 2 stator 4, 20 Mounting plate 5 shafts 16, 17 ball bearing 21 Aligning member 22 Inner surface of centering member (inner curved surface)

Claims (3)

(57) [Claims] 1. A rotor, a stator that rotatably accommodates the rotor with a gap inside, and a pair of stators that accommodate the rotor and are attached to both ends of the stator so as to close respective openings of the both ends. And a ball bearing that supports the shaft of the rotor is fixed to each of the mounting plates, and a centering member is provided around at least one of the pole bearings. And the aligning member is provided on the entire circumference of one of the ball bearings.
The inner surface of the aligning member that is in contact with one of the ball bearings is formed over the entire circumference of the ball bearing along the axial direction of the rotor.
By the curved surface protruding toward the ball bearing side
When formed , the motor is characterized in that the centering member supports the ball bearing by line contact along the circumferential direction at the center of the inner surface. 2. A rotor, a stator for rotatably housing the rotor with a gap inside, and a bottomed cylindrical case for housing the stator housing the rotor therein.
And a mounting plate that closes the opening of a bottomed cylindrical case that houses the stator therein, and one ball bearing that pivotally supports the shaft of the rotor is fixed to the bottom of the case. A motor in which the other ball bearing that pivotally supports the shaft of the rotor is fixed to the mounting plate, and a centering member is interposed around at least one of the pole bearings. The member is placed around the entire circumference of one of the ball bearings.
The inner surface of the aligning member that is in contact with one of the ball bearings is formed over the entire circumference of the ball bearing along the axial direction of the rotor.
By the curved surface protruding toward the ball bearing side
When formed , the motor is characterized in that the centering member supports the ball bearing by line contact along the circumferential direction at the center of the inner surface. 3. The aligning member is made of synthetic resin.
The motor according to claim 1 or 2, wherein the motor is provided.