JPS62126851A - Magnetic pole of pulse motor - Google Patents

Abstract

PURPOSE:To make it possible to reduce the weight and decrease the inertia moment in a simple constitution by making the thickness of plate on the outside circumference of the disc magnetic pole thinner than the portion the radius of which is small. CONSTITUTION:On the outside circumference of a disc magnet pole 1-1 a tooth portion 2 is provided. By providing an additional disc pole 11 in the middle portion of this disc pole 1-1, the thickness of the plate on the outside circumference of the disc pole is made thinner than the portion the radius of which is small. By selecting the thickness of plate of pole at the value in inverse proportion to the radius in principle, the flux density is kept constant on the disc, i.e. the flux density is kept to the extremity that no magnetic saturation may arise, and the unnecessary plate thickness is eliminated.

Description

[Detailed Description of the Invention] [Summary] This invention reduces the weight by making the outer peripheral part of a disc-shaped magnetic pole whose outer peripheral part has a tooth shape thinner than the part where the radius is small. If it is a rotor, the inertia factor is further reduced by one.

[Industrial application field]

The present invention relates to reducing the weight of an electric pulse motor, and more specifically, to making the outer peripheral part of a disc-shaped magnetic pole thinner than the part having a smaller radius.

Furthermore, the inner rotor type also reduces the inertia factor and is used in locations where weight reduction and high tracking performance are required.

The main structure of a pulse motor, also called a step motor or a stepper, is shown in FIGS. 5 to 7.

In the same figure, ■ is a disk-shaped magnetic pole with tooth shapes on the outer periphery;
2 is a toothed portion of the disc-shaped magnetic pole 1, 3 is a core, 4 is a permanent magnet,
5 is a mandrel, 6 is a wire ring, 7 is an outer magnetic pole, 8 is a toothed portion of the outer magnetic pole 7, 9 is a portion where the magnetic flux density is highest, and 10 is a line of magnetic force. FIG. 6 shows a perspective view of a disc magnetic pole 1 having tooth profiles on its outer periphery. The disc-shaped magnetic pole is made of a material having high magnetic permeability, such as soft iron. There are various types of pulse motors, but one example has four disk-shaped magnetic poles, numbered 1-1 to 1-4, and their tooth profiles are offset from each other by A pitch in the rotation direction. . As shown in the perspective view of FIG. 7, the opposing magnetic pole that acts with this magnetic pole tooth profile has a tooth profile located on the inner peripheral side of the outer magnetic pole 7 and protruding toward the center. The material is long in the direction and covers all four disk magnetic poles, and is made of the same high magnetic permeability material as the disk magnetic pole 1. The tooth profile 2 located on the inside and facing outward and the tooth profile 8 facing from the outside inward are close to each other and face each other. Similarly, the core 3 is made of a high magnetic permeability material. The permanent magnet 4 is magnetized in the axial direction, and is made of ferrite, rare earth, cobalt magnet, or the like.

The wire rings 6-1 and 6-2 are TL magnetic wire rings, and external control) 1) A pulse current is applied by the circuit to generate a magnetic field in the axial direction, and the direction is Independently, both the same and opposite directions of magnetization of the permanent magnet 4 can be generated. Then, by selectively pulse-exciting only the predetermined magnetic poles with the electromagnetic coil, the rotor is moved to two tooth-shaped pitches (in the case of one-phase excitation, two-phase excitation) depending on the relationship with the magnetic field of the permanent magnet 4. It rotates by an angle of . A typical example of magnetic lines of force at this time (l-phase excitation) is shown at 7 in FIG. The mandrel 5 is made of a non-magnetic material such as stainless steel.

In addition, the structure of FIG. 5 and the above explanation (d pole 1 and magnetic pole 'l are
Any of them can be used as a rotor or a stator. In addition, the tooth profile of the outer magnet (7) may be omitted for attachment of the wire ring 6.

These pulse motors have often been used in automatic B machines, but recently they have also been increasingly used in article gripping parts or joint parts at the tips of articulated robots. Accordingly, there has been a demand for light-weight, high-performance pulse motors.

[Problems to be solved by the prior art and the invention] The disc-shaped magnetic pole whose outer periphery is tooth-shaped in the conventional pulse motor has a sixth
As shown in the figure, it is often manufactured by punching out a magnetic base material with a uniform thickness using a press, and the thickness of the plate is determined by the following two conditions.

The first condition is magnetic saturation at the tooth tip 2, and the second condition is magnetic saturation at the tooth tip 2.
The condition is magnetic saturation at a small radius point, that is, near the outer diameter 9 of the core 3.

In other words, the first condition is an important point that supplies lines of magnetic force to generate the rotational force of the remoter through attraction with the opposing magnetic poles, and a decrease in the lines of magnetic force due to magnetic saturation directly means a decrease in the rotational force. . - The coughing part is also a part where it is desired to reduce the weight and, if this is a rotor, further reduce the moment of inertia, and minimize the cross-sectional area of the tooth tip to the extent that magnetic saturation does not occur. The second condition is that the lines of magnetic force from the outer periphery to the center of the disc have the same thickness as the disc-shaped magnetic pole, so the cross-sectional area facing the radial direction decreases as the radius decreases. Magnetic flux density increases. If magnetic saturation were to occur, the lines of magnetic force at the outer periphery would also be reduced and the rotational force would be reduced, so magnetic saturation cannot be tolerated here either.

Therefore, in consideration of the above conditions, a thicker plate thickness was actually selected for the outer peripheral portion of the disc-shaped magnetic pole.

This results in an unnecessary increase in weight and, in the case of a rotor, an increase in the moment of inertia.

The present invention was devised in view of these points.
The object of the present invention is to provide a magnetic pole for a pulse motor that has a simple configuration and can reduce the weight and further reduce the moment of inertia if the rotor is a rotor.

[Means for solving problems]

The above problem can be solved by making the outer circumference of the disc-shaped magnetic pole thinner than the part where the radius is smaller.

[For production]

If leakage magnetic flux is ignored, the magnetic flux density of the magnetic field lines in the radial direction of one disc-shaped pole is inversely proportional to the radius of that location. Therefore, by selecting the plate thickness of the TJiI pole to a value inversely proportional to its radius, the magnetic flux density can be kept constant over the disk, that is, the magnetic flux density as low as possible without causing magnetic saturation, and the unnecessary plate thickness can be eliminate.

〔Example〕

The gist of the present invention will be specifically explained below with reference to embodiments shown in the drawings. The same reference numerals indicate the same objects throughout the figures.

FIG. 1 shows a cross-sectional view of one embodiment, in which 1-1 is a disc-shaped magnetic pole having a tooth profile 2 on the outer periphery, and 1) is an additional disc-shaped magnetic pole.

FIG. 2 shows another embodiment of a disk-shaped 6H pole 12 whose plate thickness is tapered and has a chevron on its outer periphery.

The disc-shaped magnetic pole 1-1 when the present invention is used differs from the disc-shaped magnetic pole 1 when the present invention is not used only in plate thickness,
The other shapes are the same and there are 3 pieces.

Figures 3 and 3 show the configuration of a pulse motor that uses all of the additional disk magnetic poles 1). Disc-shaped magnet! '+-+ 1-1, the plate thickness is selected to be thin until just before magnetic saturation occurs in the toothed portion 1. Therefore, it enters the core 3 from the tip of the tooth in the axial direction (the magnetic flux density is highest at the portion 9 that reaches the outer periphery of the core, causing magnetic saturation, so the additional disc-shaped magnetic pole 1) is in close contact with the disk magnetic pole 1-1 and 7
They are attached concentrically.

As a result, the disk-shaped magnetic pole 1-1 has the same effect as if it were made thicker, and magnetic saturation in the portion 9 is eliminated. This procedure is the same for the disc-shaped magnetic poles 1-4.

In the disk-shaped magnetic poles 1-2 and 1-3, there is no permanent (additional disk magnetic pole 1 because the magnetic gland moves in and out of the 5-stone 4) magnetic saturation at the location where the radius is larger than that of the portion 9. does not occur.

The outer diameter of the disc-shaped magnet↑・kl is 21 mm, and the outer diameter of core 3 is 13
By applying the present invention, the thickness of the disc magnetic pole Ll could be reduced to 2/3 of that of the conventional one.

When the present invention is applied to concaves and trochanters, the 1j7 jl moment, which is an important characteristic required for normal smoke, is reduced. That is, the inertial moron l-1 is I=mr2, where nl is the mass at the point where the water diameter is r.

Therefore, as the radius becomes larger, the thickness of the shaft 7 can greatly contribute to the reduction of the moment of inertia l- by 2, and the responsiveness of the rotor can be improved.

The embodiment shown in Fig. 1 uses stacked punched parts for the purpose of reducing the cost of magnetic pole parts, but the change in plate thickness as shown in Fig. 2 is d! If it is formed from a single M-tapered C type part, the parts cost will be high, but it is effective in pursuing the ultimate reduction in weight. That is, the taper allows the plate thickness of the disc-shaped magnetic pole to be set to the very limit without causing magnetic saturation at any radial position, thereby eliminating unnecessary importance.

FIG. 4 shows an example of application of the tapered disc magnetic pole I2.

In the figure, the wire ring 13 is wound directly on the core 3 and the tapered disk crosspiece (the hook 12).In general, the wire ring is pre-wound as a component, like the wire ring 6 in FIG. This is because the machining cost is lower.However, when performance is given priority over machining cost, the configuration shown in Fig. 4 is adopted.In particular, the outer magnetic pole 7 is assembled. When used as a rotor in the arm of a robot, the ability to shorten the axial length is also highly appreciated.In addition, in Fig. 4, the disc magnetic poles 12 are used only at two outer locations, but they can be used at all four locations. Of course, magnetic poles 12 can also be used.

〔Effect of the invention〕

In view of the above, by using the magnetic poles of the pulse motor according to the present invention, the heavy load of the pulse motor can be reduced, and when the present invention is used in the rotor, the moment of inertia can be reduced, and the quick response of the pulse motor can be improved. Improved, 1F, like the tip of a robot's arm! Its practical effects are especially great in applications where product reduction and performance are pursued.

[Brief explanation of drawings]

Fig. 1 shows one embodiment of the present invention, Fig. 2 shows another embodiment of the invention, Fig. 3 shows a pulse motor using the magnetic JM of the first embodiment, and Fig. 4 shows a second embodiment. A pulse motor using &i I'r2, No. 5M is a conventional pulse motor, Fig. 6 is a conventional pulse motor with a circle (reciprocal magnet (ball), and Fig. 7 is an outer magnetic pole of a conventional pulse motor. In the figure, ■ is a disk magnetic pole, 2 is a disk f5 (toothed part of the pole, 1) is an additional +Jx Til pole according to the present invention, and 12 is a disk-shaped magnetic pole according to the present invention using a taper. . 4th -

Claims (1)

[Claims] In an electric pulse motor having a disc-shaped magnetic pole (1) whose outer periphery has a tooth shape (2), the thickness of the outer periphery of the disc-shaped magnetic pole (1) is defined as the part where the radius is small. The magnetic pole of a pulse motor is characterized by being thinner than the plate thickness of.