JPH0733583Y2 - Stepping motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a stepping motor, and more particularly to a stepping motor having an Alnico type casting magnet on the rotor side.

[Conventional technology]

Conventionally, a stepping motor of the type shown in FIG. 4 has been developed. That is, in this type, the rotor 100 is configured to include the rare earth magnet 101 and the magnetic core 102, which is sandwiched and fixed from both sides, and magnetic poles are respectively formed on the outer peripheral surface. By the way, the type using this rare earth magnet is
Since the magnet has a feature that it has a high coercive force and a high energy product in which the demagnetization phenomenon does not easily occur,
As shown in the figure, even if the thickness W of the rare earth magnet 101 is thin, a motor with high characteristics can be obtained, but it has a drawback of high cost.

Therefore, for example, as shown in FIG. 6, a magnetic core 104 is formed by laminating thin silicon steel plates or the like whose both sides are insulated as the previous rotor and joining and integrating them by caulking pins 103.
And a core Alnico-based cast magnet 105 having a large thickness, which is partially fitted and joined to the core 104, has been proposed. By the way, the Alnico cast magnet used as this permanent magnet is an alloy containing iron, nickel, cobalt, and aluminum as the main elements, has a very high residual magnetic flux density, and is lower in cost than rare earth magnets. High-performance motors are possible depending on how they are used.

[Problems to be solved]

By the way, in such a motor, in order to obtain a high performance motor, it is advantageous to increase the magnetic flux (Φ) shown in the following equation as much as possible.

Φ = B × S (where B is the magnetic flux density, S is the area where the flux passes through in the permanent magnet) By the way, in the case of general permanent magnets including the usual Alnico cast magnet, As shown in the graph in Figure 7,
In the magnetization curve 106 showing the characteristics of the permanent magnet, the residual magnetic flux density B has a correlation with the thickness of the permanent magnet. That is, a large thin towards the case B ₂ when the (P ₁ point) thicker than B ₁ (P ₂ points) for the residual magnetic flux density B, indefinitely there is a certain limit to their size Since it cannot be increased, in order to obtain a large magnetic flux (Φ), it is necessary to increase the cross-sectional area (S) of the portion through which the flux of the permanent magnet passes.

By the way, in the motor having the above-mentioned structure, as shown in FIG. 6, the Alnico cast magnet 105 is used for the sake of ensuring the area α for mounting the crimping pin 103 on the outer edge side of the core 104. The area (S) of the region β through which the flux passes cannot be greatly increased, in other words, a very large magnetic flux cannot be obtained, and it is difficult to obtain a motor with high characteristics and high performance.

Therefore, in view of the above-mentioned conventional drawbacks, the present invention has an object to provide a stepping motor capable of achieving high characteristics and high performance even in a type in which a laminated core and an alnico magnet are combined. It is a thing.

[Means for solving problems]

That is, in the stepping motor according to the present invention, the rotor rotatably mounted in the stator is formed by laminating thin plate-shaped magnetic bodies and caulking holes are provided at least in the innermost one to be joined by caulking, and magnetic poles are provided on the outer peripheral surface side. Forming a pair of cores, a columnar body having a substantially columnar shape fixed to a recess between the cores, and a substantially ring shape fixed to the outer edge side of the gap portion between the cores and outside the columnar body. And an alnico-based cast magnet composed of a ring body forming

[Action]

In the motor of this invention, the thin plate-like one that is the core is integrally joined in a laminated state by half punching, in other words, there is no need for a pin for caulking and there is no need for a space for mounting the pin for caulking. A ring body in which an Alnico-based cast magnet is formed in a ring shape is attached by utilizing the space that is not required and is open, that is, the outer edge side of the gap portion between the cores, and the stator is correspondingly provided. Since the magnetic flux passing through the side increases, the performance of the motor can be improved.

〔Example〕

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

FIG. 1 shows a stepping motor according to the present invention. The stepping motor is composed of a stator 1 and a rotor 2 having an alnico type casting magnet which will be described later.

Reference numeral 3 in the drawing is a shaft, which is fixed to the rotor 2 side.

The stator 1 has a structure in which a coil 4b is formed on an iron core 4a portion, which is formed by cutting a large number of teeth (not shown) along the axial direction of the shaft 3, on the inner peripheral surface side of a housing 4 formed in a substantially cylindrical shape. Different magnetic poles are formed on the respective tooth flanks of the iron cores 4a adjacent to each other.

The rotor 2 is composed of a core 5 and an alnico type cast magnet 6, and is rotated by an electromagnetic force generated between the rotor 2 and the electromagnetic pole 4 on the stator 1 side. Core 5
Is composed of a pair of substantially cylindrical shape having a substantially U-shaped cross section having a recess 5a on the inner side,
As shown in FIG. 2, a large number of teeth 5b are cut in order to form the same kind of magnetic poles on the outer peripheral surface side of each core 5 facing the teeth on the stator 1 side. Each of the cores 5 is fixed to the shaft 3 side with one tooth 5b displaced from the tooth 5b on the other core 5 side by a half pitch. Further, in order to effectively prevent the hysteresis loss due to the generation of the eddy current, the core 5 is formed by laminating a large number of silicon steel plates 5c as a thin plate-shaped insulating material whose both sides are insulated as shown in FIG. Caulking hole by opening the inner one
5d is formed and pressed from the outside toward the caulking hole 5d to perform half crimping, whereby the cores 5 are joined and integrated. Therefore, the core 5 does not need to have a crimping pin attached as in the conventional case, and accordingly, it is not necessary to widely open the region γ on the outer edge side of the gap portion between the cores 5 as a space for crimping. ing.
On the other hand, the Alnico-based cast magnet 6 is made of the same material as the conventional one, that is, an alloy containing iron, nickel, cobalt, and aluminum as the main elements, and has a high residual magnetic flux density superior to that of a rare earth magnet. ing. However, since the alnico type cast magnet 6 is inferior to the rare earth magnet in the energy product which is an index showing the quality of the magnetic characteristics, the flux is increased by increasing the flux accordingly. Therefore, as shown in FIG. 2, the Alnico cast magnet 6 is composed of a cylindrical body 7 and a ring body 8. The flux can be increased as much as the flux passes from the 8a side. The cylindrical body 7 is thick and formed in a cylindrical shape. The ring body 8 has a ring shape having a through hole 8a capable of penetrating the columnar body 7 and is formed to have a small thickness. The cylindrical body 7 and the ring body 8 are fixed to the recess 5a of the core 5 while the ring body 8 inserts the cylindrical body 7 and the outer edge of the gap portion between the cores 5 is formed. It is designed to be fixed to the part side.

Therefore, according to the stepping motor of this embodiment, the pin for caulking is not used, and the ring body 8 is provided in the vicinity of the outer edge portion side of the gap between the open cores 5, and the ring body Since the magnetic flux can be increased by the amount corresponding to the flux of 8, it is possible to improve the performance of the stepping motor.

〔effect〕

As described above, according to the stepping motor according to the present invention, the thin plate-shaped magnetic body can be joined and integrated without using the conventional crimping pins, so that it can be opened. A ring body with a thin dimension is arranged in a state where a cylindrical body is inserted in the outer edge side of the gap portion between the cores, which can enhance the magnetic flux, and as a result, a rare earth magnet A torque characteristic equivalent to that of a motor using is obtained, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a stepping motor according to the present invention, FIG. 2 is a schematic perspective view showing a rotor portion of the stepping motor according to the present invention, and FIG. 3 is a lamination of a rotor side core portion according to the present invention. Sectional view showing a crimped state, No. 4
FIG. 5 is a sectional view showing a stepping motor using a conventional rare earth magnet, FIG. 5 is a sectional view showing a rotor portion shown in FIG. 4, and FIG. 6 is a sectional view showing a conventional rotor using an alnico type cast magnet. FIG. 7 and FIG. 7 are graphs showing the relationship between the residual magnetic flux density and the coercive force of the Alnico cast magnet used on the rotor side. 1 ... Stator, 2 ... Rotor, 5a ... Recess, 5c ... Magnetic material, 5d ... Caulking hole, 5 ... Core, 7 ... Cylindrical body, 8 ... Ring body, 6 ... Alnico type cast magnet.

Claims (1)

[Scope of utility model registration request] 1. A rotor (2) rotatably mounted in a stator (1), wherein a thin film magnetic body (5c) is laminated and at least an innermost portion thereof is provided with a caulking hole (5d). A pair of cores (5) joined to each other and having magnetic poles formed on the outer peripheral surface side, a columnar body (7) having a substantially columnar shape fixed to a recess (5a) between the cores (5), and the core (5). A) an alnico-based cast magnet (6) consisting of a ring body (8) having a substantially ring shape fixed to the outer edge side of the gap portion between the two) and the outer side of the columnar body, and a stepping step comprising: motor.