JPS6331461A - Stepping motor - Google Patents

Abstract

PURPOSE:To reduce the size and the thickness of a stepping motor by forming inner and outer stator yokes in U-shape, superposing and connecting the outer peripheries. CONSTITUTION:A stepping motor has outer stator yokes 18 and 19 formed by punching an iron plate in U-shape and inner stator yokes 20 and 21 formed by punching similarly to the outer yokes. The motor also has a stator coil 30 comprising coils 24 and 25 wound on coil bobbins 22 and 23 which are shaped to be within the width W. In this case, the outer yokes 18 and 19 and inner yokes 21 and 21 are so composed that the outer peripheries 31 and 32 are superposed closely, and pectinated teeth 33 and 34 formed integrally on the inner peripheries are alternately combined. Thus, the magnetic flux formed by the coil 24 is fed, for example, through the yokes 18 and 20, the rotor magnet, the yoke 18 to reduce its magnetic resistance.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a stepping motor.

BACKGROUND OF THE INVENTION In recent years, information-related equipment and OA equipment are increasingly being controlled by microcomputers, and stepping motors, which can be easily controlled digitally, are increasingly being used as the driving source for these equipment. It's coming.

Furthermore, as these devices become smaller and thinner, it is strongly desired that the stepping motors used therein be made smaller and thinner as well.

An example of the conventional stepping motor mentioned above will be described below with reference to the drawings. FIG. 3 shows a conventional stepping motor, and 1.2 is a stator yoke constructed using a punched iron plate. Stator yoke 1
, 2 has comb-shaped teeth 40 on the inner periphery as shown in FIG. 3 and 4 in FIG. 3 are inner stator yokes that are made of a punched iron plate and have comb-shaped teeth like the outer stator yokes 1 and 2, and the outer periphery of the inner stator yokes fits inside the outer stator yokes 1 and 2. It's starting to get crowded. Furthermore, outer stator yokes 1 and 2 and inner stator yoke 3
, 4 has a structure in which the comb teeth are arranged alternately on the same circumference.

5.6 is a bobbin that fits between the outer periphery and teeth of the outer stator yokes 1, 2 and the inner stator yokes 3, 4;
, 8 are coils wound around the bobbin 6.6, respectively. 9,
10 is a bracket, 11° and 12 are multi-pole magnetized rotor magnets, 13 and 14 are bearing metals attached to the platen 9 and 10, and 15 is a shaft.

The operation of the stepping motor configured as described above will be explained below. When the coil 7 is energized, the magnetic flux generated by the coil 7 is transferred to the outer stator yoke 1. Rotor magnet 11. It passes through a route called the inner stator yoke 3. Similarly, on the right half side, the outer stator yoke 2. Rotor magnet 12. A magnetic flux is generated that passes through the path of the inner stator yoke 4.

If the excitation voltage polarities of the coils 7 and 8 are reversed here, the direction of the magnetic flux passing through each magnetic path is also reversed. Therefore, the polarity of each of the teeth 40 of the outer stator yokes 1, 2 and the inner stator yokes 3, 4 is reversed, and the rotor magnets 11 and 12 rotate accordingly.

A second conventional example is shown in FIG. 1, 2, and 5 to 15 are the same as those in the first conventional example shown in FIG. 3, so their explanation will be omitted. 16.17 is an inner stator yoke, whose operation is the same as that in FIG. 3, but as shown in FIG. 5, the inner stator yoke 1θ.

17 has a structure in which the ring-shaped portion on the outer periphery is omitted compared to the inner stator yokes 3 and 4 shown in FIG. 3, thereby allowing for miniaturization. Therefore, the connection between the magnetic paths of the outer stator yoke 1°2 and the inner stator yokes 16 and 17 is equivalent to the plate thickness H of the inner stator yokes 16 and 17.

Problems to be Solved by the Invention However, in the above-mentioned configuration, in the first conventional example, when the motor diameter is reduced, the inner and outer stator yokes 1,
2 and 3.4 becomes a dog, and the coil 7.8 becomes smaller, so the torque decreases rapidly. The inner stator yoke 16,1
The connection area between the magnetic passages of the outer stator yokes 16 and 17 and the outer stator yokes 3 and 4 is only the plate thickness H of the inner stator yokes 16 and 17, and therefore the magnetic resistance becomes large, which also causes a reduction in torque.

In view of the above-mentioned problems, the present invention aims to provide a stepping motor that can be downsized and has less torque down.

Means for Solving the Problems In order to solve the above problems, the stepping motor of the present invention has a configuration in which the inner and outer stator yokes are each formed into a U-shape, and the outer peripheries of the inner and outer stator coils are overlapped and connected. It is equipped with the following.

Function: With the above-described configuration, the width of the outer stator yoke and the inner stator yoke can be reduced in one radial direction of the stepping motor (direction P in Fig. 2).
The dimensions in the direction are the same as in the conventional example. ) Therefore, it is possible to make the stator yoke smaller and thinner, and the connecting area of the magnetic passages of the inner and outer stator yokes can be sufficiently secured at the overlapping portions of these outer peripheries, making it possible to suppress torque reduction.

Example Below, regarding a stepping motor according to an example of the present invention,
This will be explained with reference to the drawings. FIG. 1 shows a plan view of an embodiment of the invention. 18.19 in Figure 1
Reference numeral 20 and 21 indicate an outer stator yoke formed by punching an iron plate into a U-shape, and an inner stator yoke formed by punching an iron plate into a U-shape. 22.23 is a coil bobbin with a part of the sea urchin cut off so that it fits within the width W of both stator yokes 1B, 19, 20.21 (7). 1.24.
25 is a coil. In FIG. 2, the outer stator yoke 18
．． Inner stator yoke 20. Coil bobbin 22. coil 2
4 is shown in an exploded perspective view. In this embodiment, stator coil 3
Although a coil 24.25 wound around a coil bobbin 22.23 is used as the coil bobbin 22.23, the stator coil 30 may be constructed by self-fusion of the coil 24.25.

Outer stator yoke 7.18.19 and inner stator yoke 2
0.21 has a structure in which the outer circumferential portions 31 and 32 of each of the outer circumferential portions 31 and 32 are in close contact with each other over the entire surface and overlap each other as shown in FIG. Also, comb-like tooth portions 33 are integrally formed on the inner circumferential portions of both stator yokes 18, 19, 20, and 21. ．． 34 are also combined alternately.

Therefore, for example, the magnetic flux generated by the coil 24 is generated by the outer stator yoke 18. Inner stator yoke 20. The flow does not flow through the rotor magnet (see Fig. 3) and the outer stator yoke 18, and as in the first conventional example, the magnetic connection area of the side stator yoke can be increased and magnetic resistance can be reduced. Can be done.

Effects of the Invention Since the present invention is configured as described above, it is possible to reduce the dimension of one radial direction (direction P in Fig. 2) of the stepping motor and to sufficiently increase the magnetic connection area between the inner and outer stator yokes. Therefore, it is possible to provide a stepping motor with less torque down.

Furthermore, the U-shaped stator yoke has the advantage of being simpler in shape, easier to manufacture, and better suited for mass production than conventional stator yokes, and its industrial advantages are extremely large.

[Brief explanation of drawings]

FIG. 1 is a plan view of a stepping motor according to an embodiment of the present invention, FIG. 2 is an exploded perspective view showing an outer stator yoke, an inner stator yoke, and a stator coil in an embodiment of the present invention. The figure is a cross-sectional view of the first conventional example, and Figure 4 is a cross-sectional view of the third conventional example.
The sketch of the outer stator yoke in the figure, and FIG. 6 is a sectional view of the second conventional example. j8.19...Outer stator yoke, 2Q, 21
...Inner stator yoke, 30...Stator coil, 31.32...Outer circumference, 33.3
4...Teeth. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure P 33.34--- @
yP Figure 4 Figure 5

Claims (1)

[Claims] It consists of inner and outer stator yokes each having interlocking comb-like teeth on their inner periphery, a stator coil, and a multipolar magnetized rotor magnet, and each of the inner and outer stator yokes is formed into a U-shape. In addition, the stepping motor is characterized in that the outer peripheries of the inner and outer stator yokes are overlapped and brought into contact with each other.