JPH0526926Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention is a permanent magnet stepping motor (hereinafter referred to as
It is called PM type stepping motor. ) relates to a rotor bearing support device.

BACKGROUND TECHNOLOGY As is well known, a stepping motor is a motor that rotates by one advance angle in response to one input signal, and can be broadly classified into several types of structures based on the difference in rotation principle. As shown in Fig. 7, the conventional structure of the PM type stepping motor, which is one of them, has a plurality of magnetic pole teeth 1a located at equal intervals on the inner cylindrical surface and protruding in the axial direction. Two inner stator yokes 1 and two outer stator yokes 2 having magnetic pole teeth 2a having the same shape and pitch as the magnetic pole teeth 1a are provided. are staggered at equal intervals, that is, in electrical angles.
They are located on the same axis with a 180° shift.

Between the inner stator yoke 1 and the outer stator yoke 2 having these magnetic pole teeth 1a and 2a, there is a stator coil 3 for switching stator excitation.
4 is wound around two coil bobbins 13 each having a cylindrical shape and having flanges at both ends thereof. In order to determine the direction of rotation, the two inner stator yokes 1 are coaxially positioned back to back to each other with a 1/4 magnetic pole pitch shift in the circumferential direction, that is, a 90° electrical angle shift. Although not shown in the drawings, the inner stator yoke 1 is positioned using holes and protrusions provided in the inner stator yoke 1. These inner and outer stator yokes 1 and 2
A rotor 6 is disposed inside the cylindrical portion formed by the magnetic pole teeth 1a and 2a. The rotor 6 includes a permanent magnet 6a whose outer periphery is subjected to multipolar magnetization and a rotor shaft 6b. The rotor 6 has a bearing 11 held on the outside of both outer stator yokes via bearing holding plates 9 and 10.
is rotatably supported by a permanent magnet 6 on the outer periphery.
a, and magnetic pole teeth 1a and 2a of the inner and outer stator yokes.
A slight distance between the cylinder and the cylindrical part is maintained. That is, stator coils 3, 4,
With inner stator yoke 1 and rotor 6 inserted,
It has a structure in which two outer stator yokes 2 are connected to each other. Since this connection maintains the strength of the motor, it has become common to use robust and reliable methods such as welding, gluing, press-fitting, and caulking. In addition, the structure shown in FIG. 8 has bearings 11, 1 directly attached to the two outer stator yokes 12.
6 is attached, but since the rotor length is shorter than that of the structure shown in FIG. 7, it is not possible to obtain a torque commensurate with the external dimensions, so it is not common.

Problems to be solved by the invention The PM type stepping motor mentioned above has many parts such as a stator yoke and a bearing holding plate between the two bearings that support the rotor, making it difficult to align the two bearings. Compared to conventional motors, the distance between the rotor and stator is narrower, and there is a greater possibility that the rotor and stator will come into contact with each other, which can cause rotor rotation failure. However, with the conventional structure in which bearings are attached to the outer stator yoke, it is not possible to inspect the rotor for malfunctions until the motor is completed, and the outer stator yoke is firmly connected using methods such as welding. Therefore, even if defective rotation products are selected, it is not easy to correct them.

Therefore, in order to improve the rotation failure of the rotor of conventional PM type stepping motors, a single bearing structure as shown in Fig. 9 or one bearing holding plate on one side fixed with screws as shown in Fig. 10 has been developed. is proposed. However, even with such a single bearing structure, the cost of the bearing is high, and even if the rotor rotates smoothly when no load is applied to the rotor shaft, the rotor may come into contact with the stator due to overload during actual use. In addition, the structure in which the bearing holding plate on one side of Fig. 10 is fixed with screws increases the number of parts and man-hours due to screws, and also has problems such as the fact that the outer stator yoke cannot be used in common on the front and rear. It had a point.

In view of the above problems, the present invention improves the coaxiality of the two bearings that support the rotor of a PM stepping motor, and creates a high-quality stepping motor that can be easily mass-produced and allows rotor rotation inspection to be performed during motor assembly. A bearing support device is provided.

Means for Solving the Problems In order to solve the above-mentioned conventional problems, the stepping motor bearing support device of the present invention has a plurality of magnetic pole teeth coaxially protruding in the axial direction so as to intertwine with each other. Inner and outer stator yokes with notches provided at the root portions between the magnetic pole teeth; a cylindrical portion located between the inner and outer stator yokes into which the magnetic pole teeth are fitted; and flanges projecting from both ends of the cylindrical portion. The coil bobbin is equipped with a coil bobbin and a bearing that rotatably supports the rotor shaft, and the central part of one outer end surface of the coil bobbin holds a plurality of protrusions and a bearing that engage with the notches between the outer stator yoke magnetic pole teeth. The other flange has a plurality of protrusions that are fitted into holes provided in the inner stator yoke to coaxially position the magnetic pole teeth of the inner stator yoke and the coil bobbin. It is said that the configuration is as follows.

Effect With this configuration, the coil bobbin and the inner stator yoke are positioned coaxially by the protrusion and the hole, and the bearing holding part is provided on the coil bobbin, so when the inner stator yoke and the coil bobbin are assembled, the bearing can be attached easily. Coaxial positioning is possible and rotor rotation inspection can be performed. Since the inner stator yoke is inserted into the outer stator yoke, the bearing, which is positioned coaxially with the inner stator yoke, and the outer stator yoke can be coaxially positioned, and assembly accuracy can be improved. Therefore, the number of parts around the bearing can be reduced, the rotation of the rotor can be inspected during assembly, and high-precision assembly can be easily achieved.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sectional view of a stepping motor using a bearing support device according to the present invention.
In FIG. 1, 1 is an inner stator yoke located at equal intervals on the inner cylindrical surface and has a plurality of magnetic pole teeth 1a protruding in the axial direction; 2 is an outer stator yoke; To prevent the leakage of magnetic flux in the axial direction from the magnetic pole teeth 1a of the inner stator yoke 1 located between the magnetic pole teeth 2a of the same shape and the same number of magnetic pole teeth 1a of the inner stator yoke 1 and the adjacent magnetic pole teeth 2a. A notch 2b is provided for this purpose. The magnetic pole teeth 1a and 2a of the inner stator yoke 1 and the outer stator yoke 2 are intertwined with each other, coaxially facing each other, and are shifted by 180 degrees in electrical angle. 3 and 4 are stator coils for switching excitation of the stator located in an annular space surrounded by the outer periphery of the cylindrical portion constituted by the magnetic pole teeth 1a and 2a, the inner stator yoke 1 and the outer stator yoke 2; It is wound around a cylindrical portion 5a of a coil bobbin 5 according to the present invention shown in the figure. A plurality of projections 5c and a bearing holding portion 5d are provided on one flange portion 5b side of the coil bobbin 5 to engage with the notch portion 2b between the magnetic pole teeth 2a of the outer stator yoke 2. A hole 5e is formed in which the magnetic pole tooth 2a of the outer stator yoke 2 is inserted. Further, the inner stator yoke 1 is attached to the other flange portion 5f of the coil bobbin 5.
A plurality of protrusions 5g are provided which fit into the bobbin mounting reference holes 1c to coaxially position the magnetic pole teeth 1a and the bearing holding portion 5d.

The coil bobbin 5 of the present invention has a thick bearing holding portion 5.
d and the thin flange portion 5b are connected over a wide area by a plurality of protrusions 5c, and the bearing holding portion 5d has a three-dimensional shape, so it has good dimensional stability and strength. That's enough.

6 is a rotor provided with a permanent magnet 6a and a rotor shaft 6b.

7 is a bearing inserted into the bearing holding portion 5d of the coil bobbin 5. A rotor 6 is rotatably supported via this bearing 7. Reference numeral 8 denotes a motor mounting plate coupled to the outside of the outer stator yoke 2.

In this assembly, first, the stator coils 3 and 4 are wound around the coil bobbin 5 by a predetermined amount, and an external extraction process is performed. Next, the bearing 7 is press-fitted into the bearing holding portion 5d. Next, the inner stator yokes 1 are assembled back to back with the step angles shifted, and the coil bobbin 5 with the windings and bearings press-fitted is aligned with the bobbin mounting reference hole 1c and the positioning protrusion 5g on one side of the inner stator yoke 1. combine. Next, the rotor 6 is fitted into the cylindrical portion formed by the magnetic pole teeth 1a of the inner stator yoke 1 from the other open side, and the end of the rotor shaft 6b is fitted into the bearing 7. and,
Similarly, the coil bobbin 5, which has undergone a predetermined process, is assembled to the other inner stator yoke 1. This state is shown in FIG. 4, and as can be seen from the figure, the coil bobbin 5 is
The structure is such that the assembly around the bearing can be completed by combining the parts. Therefore, the rotation of the rotor 6 can be inspected in this state, and the coaxiality of the bearing 7 can be easily adjusted.

Next, the outer stator yoke 2 equipped with the motor mounting plate 8 and the other outer stator yoke 2 are inserted from both ends into the holes 5e of the coil bobbin 5 with their magnetic pole teeth 2a inserted, and the outer stator yokes are joined together. It will be completed.

As can be seen from the above explanation, in the conventional structure, the number of parts interposed between the two bearings that support the rotor is six in total, consisting of two each of the bearing holding plate, outer stator yoke, and inner stator yoke. In terms of coaxiality, the structure was supported through the outer stator yoke, but in the present invention, there are four intervening parts between the coaxial bearings: two each of the inner stator yoke and the coil bobbin with a bearing holding part. Also, the coil bobbin 5 and inner stator yoke 1 are connected to the bobbin mounting reference hole 1c.
Because of the structure in which the bearing 7 is held by the coil bobbin 5 and positioned by the positioning protrusion 5g,
It is possible to easily maintain the coaxiality of both bearings with high accuracy, and the configuration around the bearing is completed in the state shown in Figure 4, and it is possible to confirm the coaxiality of the bearing 7 and inner stator yoke 1 in this state. In this state, it is possible to check whether the rotor 6 is rotating properly, modify the parts, etc.
Replacement can be done easily. Incidentally, since the outer stator yoke 2 has no relation to the coaxiality of the bearing 7, work management during the final joining process can be easily performed.

Furthermore, the bearing retaining plate on the side opposite the output shaft as in the conventional example (FIG. 7) is no longer necessary, the number of parts is reduced, and productivity can be streamlined.

In addition, in the explanation so far, the bearing support device according to the present invention has been applied to both the output shaft side and the non-output shaft side, but when an extreme lateral pressure load is applied to the rotor shaft 6b, the bearing is held only by resin, so Strength is insufficient. Therefore, as can be seen from the load distribution diagram shown in Figure 5, there is a large difference in the supported load between the bearing on the output shaft side and the bearing on the side opposite to the output shaft, so even if a considerable lateral pressure load is applied to the rotor shaft. Since the effect on the side opposite to the output shaft is minimal, as shown in Figure 6, the output shaft side has the conventional structure, and by using the bearing support device of the present invention only on the side opposite to the output shaft where the lateral pressure is small, it is possible to The coaxiality between the bearings can be easily maintained with high precision, making it possible to withstand extreme loads, resulting in a stepping motor of excellent quality.

In Fig. 5, P ₁ is the lateral pressure load applied to the rotor shaft 6b, P ₂ is the reaction force applied from the output shaft side bearing to the rotor shaft, P ₃ is the reaction force applied from the non-output shaft side bearing to the rotor, and a is P ₁ , P ₂ distance, b is P ₂ ,
The distance between P ₃ is P ₃ =a/bP ₁ P ₂ =P ₁ +P ₃ =b+a/bP ₁ .

Effects of the invention As is clear from the above explanation, if the bearing support device of the invention is used, the number of parts interposed between the two bearings that support the rotor shaft can be reduced, and the inner stator yoke and coil bobbin can be connected to holes and protrusions. Because of the structure in which the bearings are positioned by the coil bobbin and held by the coil bobbin, the coaxiality between both bearings can be maintained easily and accurately, and this can be confirmed during assembly, streamlining productivity by reducing the number of parts and increasing productivity. It has become possible to mass produce high quality PM type stepping motors, which has great practical value.

[Brief description of the drawings]

FIG. 1 is a sectional view of a stepping motor using a bearing support device according to an embodiment of the present invention, and FIG.
The figure is a front view of the same, Figure 3 is a perspective view of the coil bobbin used in the bearing support device, Figure 4 is a sectional view of the stepping motor in the middle of assembly using the bearing support device, and Figure 5 is the rotor shaft. Figure 6 is a cross-sectional view of a high-load motor to which the present invention is applied, Figures 7 and 8 are cross-sectional views of a conventional stepping motor, and Figure 9 is a load distribution diagram when a load is applied to the motor. , FIG. 10 is a sectional view of a conventional stepping motor that is intended for disassembly and modification. 1...Inner stator yoke, 1a, 2a...Magnetic pole teeth, 1c...Bobbin mounting reference hole, 2...Outer stator yoke, 2b...Notch, 3, 4...Stator coil, 5...Coil bobbin, 5a...Cylindrical part, 5b, 5f...Flange part, 5c...Protrusion part, 5d...Bearing holding part, 5e...Hole part, 5g...
...Protrusion, 6...Rotor, 7...Bearing, 8...Motor mounting plate.

Claims (1)

[Claims for Utility Model Registration] An inner and outer stator yoke in which a plurality of magnetic pole teeth coaxially protrude in the axial direction so as to intertwine with each other, and a notch is provided at the root portion between the magnetic pole teeth; The coil bobbin includes a coil bobbin located between the outer stator yokes and provided with a cylindrical part into which the magnetic pole teeth are fitted and flanges projecting on both sides of the cylindrical part, and a bearing rotatably supporting a rotor shaft. A plurality of protrusions that engage with the notches between the magnetic pole teeth of the outer stator yoke and a bearing holding portion that holds the bearing are integrally protruded from a central portion of the outer end surface on one flange side of the outer stator yoke. A coil bobbin with a bearing holding part, the other flange of the coil bobbin being provided with a plurality of protrusions that are fitted into holes provided in the inner stator yoke to coaxially position the magnetic pole teeth of the inner stator yoke and the coil bobbin. A bearing support device for a stepping motor that uses two on both outer end surfaces or one on the outer end surface on the side opposite to the output shaft.