JP2000341930A - Linear motor utilizing permanent magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent electromagnetic thrust from dropping by reducing the magnetic saturation of a yoke steel plate without increasing its thickness. SOLUTION: This linear motor is structured with a group of magnets 12, that are formed by lining up permanent magnets 10 each having a different magnetized direction along the traveling direction neighboring yoke steel plates 11, the group of magnets 12 being used as a fixed part or moving part. In this case, the number of the permanent magnets 10 which constitutes the group of magnets 12 used is an odd number.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor using a permanent magnet, and more particularly to a linear motor using a permanent magnet for reducing magnetic saturation of an iron plate for a yoke and avoiding a reduction in generated electromagnetic thrust. It relates to a linear motor.

[0002]

2. Description of the Related Art A linear motor is a type in which a moving part moves linearly while a normal motor performs a rotary movement. A linear DC motor (LDM) and a linear synchronous motor (LS
M), a linear pulse motor (LPM) and the like.

In these linear motors, a thrust is obtained by controlling a current flowing through a coil group with respect to a magnet group in which permanent magnets having different magnetization directions are alternately arranged along the running direction.

[0004] Linear motors are classified into a system using a magnet group as a fixed part and a coil group as a movable part, and conversely, a system using a coil group as a fixed part and a magnet group as a movable part. .

[0005] In such a linear motor, the magnetic field generated by the magnet group is strengthened to obtain thrust efficiently.
An iron plate for yoke is placed behind the magnet group.

[0006]

By the way, the above-mentioned magnet group is constituted by connecting a number of permanent magnets with a yoke iron plate, but since this yoke iron plate is a continuous single plate. The magnetoresistance is small, and the magnetomotive force of each magnet constituting the magnet group tends to act on the entire iron plate. For this reason, in a magnet group in which permanent magnets with different magnetization directions are alternately arranged, the magnetic field of the iron plate based on the magnetomotive force with different directions of each magnet remains without being canceled out, and the yoke iron plate is magnetically saturated. There was a problem of letting it.

[0007] As described above, when magnetic saturation occurs in the yoke iron plate, the magnetic resistance of the yoke iron plate increases, so that the magnetic field generated in the coil group by the permanent magnet decreases, and the generated electromagnetic thrust decreases. I do.

This magnetic saturation can be reduced by increasing the thickness of the yoke iron plate. However, this method leads to an increase in the cost of the linear motor, and when a magnet group is used as a movable portion, Undesirably, the movable mass increases.

The present invention has been made in view of the above-described problems of the conventional linear motor, and it is therefore an object of the present invention to reduce the magnetic saturation of a yoke plate without increasing the thickness of the yoke plate and to avoid a reduction in generated electromagnetic thrust. It is an object of the present invention to provide a linear motor using a permanent magnet that can be used.

[0010]

In order to achieve the above object, a linear motor using a permanent magnet according to the present invention includes a permanent magnet having a different magnetization direction adjacent to a yoke iron plate along a running direction. To form a group of magnets
In a linear motor using the magnet group as a fixed part or a movable part, the number of permanent magnets constituting the magnet group is odd.

A linear motor using the permanent magnets, an odd number of permanent magnets constituting the magnet group, and an even number of magnetomotive forces of the yoke iron plate allow the magnetic fluxes in the iron plate due to the respective magnetomotive forces to be mutually different. Thus, the magnetic saturation of the yoke iron plate can be reduced, and a decrease in the generated electromagnetic thrust can be avoided. In this case, it is not necessary to increase the thickness of the yoke iron plate in order to reduce the magnetic saturation, which is economical. Further, when a magnet group is used as the movable portion, an increase in weight can be avoided.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a linear motor using a permanent magnet according to the present invention will be described below with reference to the drawings.

A linear motor using this permanent magnet is:
Linear DC motor (LDM), linear synchronous motor (LS
M), a linear pulse motor (LPM), etc., as shown in FIG. 2, a plurality of strip-shaped permanent magnets 10 having different magnetization directions are alternately arranged along the running direction of the linear motor. The magnet group 12 is used.

As shown in FIG. 1, the permanent magnet 10 constitutes a magnet group 12 arranged such that the magnetization directions indicated by arrows are alternately changed to 1a, 1b, 2a, 2b, 3a. A yoke iron plate 11 serving as a yoke is provided on the back surface of the magnet group 12 so that the magnetic field generated by the magnet group 12 is strengthened so that thrust can be obtained efficiently.

This portion consisting of the magnet group 12 and the yoke iron plate 11 can constitute either a movable portion or a fixed portion of the linear motor. Further, as the movable part or the fixed part paired with the permanent magnet group 12, a normal coil group (not shown) that controls by passing a current is used.

In the linear motor having such a configuration, in this embodiment, the number of the permanent magnets 10 constituting the magnet group 12 is specified as an odd number.

Hereinafter, the permanent magnets 10 constituting the magnet group 12 will be described.
The reason why the number of is odd is described.

FIG. 4 shows a permanent magnet 1 constituting the magnet group 12.
This is a conventional example in which the number of zeros is an even number (four in the illustrated example), and the magnetomotive force generated by the permanent magnet 10 in the yoke iron plate 11 is indicated by an arrow.

In this case, the permanent magnet 10 is
The directions of the magnetomotive forces 1c, 1d, 2c, 2d, and 3c formed in the magnets are alternately opposite because the magnet groups 12 'are formed by alternately arranging the permanent magnets 10 having different magnetization directions. I have.

Incidentally, the magnet 1 constituting the magnet group 12 '
Assuming that the number of 0s is 2n, the number of magnetomotive forces generated by the permanent magnets 10 in the yoke iron plate 11 is 2n + as shown in FIG.
It becomes one.

Since the yoke iron plate 11 is a single continuous plate, the magnetic resistance is small and the magnetomotive forces 1c, 1d, 2c, 2
The magnetic flux generated by each of d and 3c tends to flow uniformly throughout the plate.

Iron plate 11 for yoke by 2n + 1 magnetomotive forces
Since the directions of the magnetomotive force of the permanent magnets 10 in the inside are different from each other, if the number is even, the magnetic flux cancels out and the magnetic field in the yoke iron plate 11 is suppressed to a small value.

However, in the conventional example shown in FIG.
Since the number 2n of the magnets 10 is an even number, the number 2n of the magnetomotive force
The value of +1 is an odd number, the magnetic flux does not cancel, the magnetic flux remains in the yoke iron plate 11, and the magnetic field in the yoke iron plate 11 increases.

When the magnetic field in the yoke iron plate 11 increases,
As a result, the yoke iron plate 11 is magnetically saturated. In this way, when magnetic saturation occurs, the magnetic resistance of the yoke iron plate 11 increases, and the magnetic field generated by the permanent magnet 10 in a coil group (not shown) located on the opposite side of the yoke iron plate 11 decreases. As a result, the generated electromagnetic thrust decreases.

On the other hand, as shown in FIG. 3, in the embodiment of the present invention in which the number of the permanent magnets 10 constituting the magnet group 12 is odd (5 in the illustrated example), Magnetomotive force 1c, 1d, 2c, 2 created in yoke iron plate 11
The directions of d, 3c, and 3d are alternately opposite as shown in FIG. 2 and the number 2n + 1 of the magnets 10 constituting the magnet group 12 is an odd number. 2n + 1 + 1 is an even number.

Thus, if the number of magnetomotive forces is even,
The magnetic fluxes in the yoke iron plate 11 due to the respective magnetomotive forces of the permanent magnets 10 cancel each other out, the magnetic field in the yoke iron plate 11 is kept small, and the magnetic saturation of the yoke iron plate 11 is avoided. Therefore, as in the present embodiment, the magnet group 12
When the number of the magnets 10 is odd, the yoke iron plate 11 is less likely to be magnetically saturated.
The magnetic field generated by the permanent magnet 10 in the coil group does not decrease,
As a result, the reduction of the generated electromagnetic thrust is reduced.

[0027]

According to the linear motor using the permanent magnet of the present invention, a permanent magnet is formed as an odd number to form a magnet group.
Since the number of magnetomotive forces in the yoke iron plate is set to an even number, the magnetic flux in the iron plate due to each magnetomotive force can be offset each other,
As a result, the magnetic saturation of the yoke iron plate can be reduced, and a decrease in the generated electromagnetic thrust can be avoided. Moreover, it is not necessary to increase the thickness of the yoke iron plate in order to reduce the magnetic saturation, which is economical. In addition, when a magnet group is used as the movable portion, an increase in weight can be avoided.

[Brief description of the drawings]

FIG. 1 is a partial front view showing a permanent magnet group of a linear motor according to an embodiment of the present invention.

FIG. 2 is a partial perspective view of the same.

FIG. 3 is a front view showing a magnetomotive force generated by a permanent magnet in the iron plate for a yoke.

FIG. 4 is a front view showing a magnetomotive force of a permanent magnet in a yoke iron plate in a conventional example in which the number of permanent magnets is an even number.

[Explanation of symbols]

1a, 1b, 2a, 2b, 3a Magnetization direction of permanent magnet 1c, 1d, 2c, 2d, 3c, 3d Magnet magnetomotive force in yoke iron plate 10 permanent magnet 11 yoke iron plate 12 magnet group

Claims (1)

[Claims] 1. A magnet group is formed by arranging permanent magnets having different magnetization directions alternately along a running direction adjacent to a yoke iron plate, and using the magnet group as a fixed portion or a movable portion. A linear motor using permanent magnets, wherein the number of permanent magnets constituting the magnet group is odd.