JPH0393454A - Magnetization of magnet for position detection - Google Patents

Abstract

PURPOSE:To enable the positions of permanent magnets to be exactly detected and reduce speed ripple by permitting a magnetic body to be used for detecting the position of a field magnet, to come in close contact with the field magnet, and by magnetizing the magnetic body with the magnetic flux of said field magnet. CONSTITUTION:On a field core 1 with previously arranged permanent magnets 2, 2,..., a magnetic body 6 before magnetized is placed with a back plate 7 on its upper section. The magnetic flux density of the permanent magnets 2, 2,... is high with 4000-5000 gausses, and so the magnetic body 6 in contact with the permanent magnets 2, 2,... is easily magnetized. Accordingly, on the magnetic body 6, magnetic poles at the same pitch as that of the permanent magnets 2, 2,... are magnetized as they are. The magnetic body 6 after magnetized is set in parallel with the field core 1 so that the permanent magnets 2, 2,... and the magnetic poles correspond with each other, one to one.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method of magnetizing a position detection magnet suitable for use in a scale for detecting the position of a field magnet of a linear motor.

"Prior Art" A linear motor is driven by generating magnetic flux by a coil provided on a slider in response to field magnetic flux caused by permanent magnets arranged in a field core, thereby generating thrust on the slider. . Further, the linear motor is equipped with a position sensor that detects the magnetic pole position of the permanent magnet in order to control the position, speed, etc. of the slider.

Next, see Figures 3 and 4 regarding the above-mentioned and near-moment events.
This will be explained with reference to the figures. First, in FIG. 3, a permanent magnet 2 is attached to the field core 1 so that N poles and S poles appear alternately.
, 2, . . . are arranged.

A slider 3 moves linearly over the permanent magnets 2, 2, . . . through a constant gap in the direction of the arrow shown in the figure. The slider 3 is provided with a coil (not shown) for generating thrust, and is further equipped with a sensor 5 for detecting the speed and position of the slider 3. This sensor 5 is adapted to move linearly in conjunction with the slider 3. Further, the sensor 5 is composed of two Hall elements 5a and 5b shown in FIG. 4(a),
They are arranged at an interval of λ/4 with respect to the magnetic poles magnetized on the magnetic body 6 (see FIG. 4<a>). The magnetic body 6 is molded into a single plate from a magnetic material with a large coercive force and a rubber material, and is attached and supported by a back plate 7 made of Fe (iron). In addition, as described above, this magnetic body 6 has a large coercive force and the direction in which it is easily magnetized (the axis of easy magnetization) is aligned in the thickness direction, so it can be easily multipolarized and magnetized. After that, it is used as a permanent magnet.

In the above configuration, when the slider 3 moves, the Hall elements 5a and 5b detect the magnetic flux of the magnetic body 6 and output the detection signal shown in FIG. 4(b). In this case, if the detection signal output by the Hall element 5a is sin θ, the detection signal output by the Hall element 5b is cos θ. Then, the speed of the slider 3 is controlled based on the frequency and phase relationship of this detection signal.

Next, a method of magnetizing the above-mentioned magnetic body 6 will be explained with reference to FIG. 5. In this figure, a magnetizing jig 10
On the upper part, there are the permanent magnets 2, 2, . . . for the field described above.
Convex portions 10a, 10a, . . . are provided at regular intervals so as to have the same pitch as the pitch of the magnetic poles of . 10a, . . . have coils 11.11. ... is wound around. On this magnetizing jig 10, with the back plate 7 facing upward, the magnetic body 6 described above is placed in contact with the convex portions 10a, loa, . . . , and then the coils l 1, 1 1,...
Apply current to... As a result, coils 11, 11 .・
A magnetic flux is generated, and the magnetic body 6 is magnetized with magnetic poles corresponding to the pitch of the convex portions 10a of the magnetization jig.

After magnetization, the magnetic body 6 is arranged in such a manner that the permanent magnets 2, 2, . . . installed in parallel.

"Problems to be Solved by the Invention" By the way, since the easy magnetization axes of the above-mentioned magnetic material are aligned in the thickness direction thereof, the magnetization pitch accuracy is good. Therefore, in the conventional magnetization method using a magnetization jig, this magnetic body is magnetized at equal pitches. Therefore, the detection signal detected by the Hall element described above has equal periods. On the other hand, the permanent magnets arranged in the field core have poor pitch accuracy and are not arranged at equal intervals. Therefore, in the conventional magnetization method, the magnetic poles of the permanent magnet and the magnetic body are misaligned, so the actual position of the slider and the phase of the detection signal output by the Hall element do not match, which can cause problems such as speed control. The accuracy of the command value deteriorates.

This causes a problem in that speed ripples occur and the slider does not move smoothly.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a magnetization method that can accurately detect the position of the magnetic pole of a permanent magnet and reduce speed ripple.

"Means for Solving the Problem" In order to solve such problems, in this invention, a magnetic material used for position detection of the field magnet is brought into close contact with field magnets arranged in advance, and the magnetic material is It is characterized in that the magnet is magnetized by the magnetic flux of the field magnet.

"Operation" A magnetic body used for position detection of the field magnets arranged in advance is brought into close contact with the field magnets, and the magnetic bodies are magnetized by the magnetic flux of the field magnets.

"Embodiments" Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory diagram for explaining a method of magnetizing a position detection magnet according to an embodiment of the present invention.

In this figure, first, permanent magnets 2, 2,...
The magnetic material 6 before magnetization is placed on the field core l in which ... is arranged, with the back plate 7 facing upward. Permanent magnet 2,
Since the magnetic flux density of 2, . . . is as high as 4000 to 5000 Gauss, the permanent magnet 2, 2. The magnetic body 6 in contact with . . . is easily magnetized. Therefore, the magnetic body 6 is magnetized with magnetic poles having the same pitch as the permanent magnets 2, 2, . . . as shown in FIGS. 2(a) and 2(b). The magnetic body 6 after magnetization is a permanent magnet 2, 2,...
... and the magnetized magnetic poles are placed in parallel to the field core l shown in FIG. 3 in a one-to-one correspondence.

When the magnetic body 6 magnetized as described above is used as a position detection magnet, the detection signals outputted by the Hall elements 5a and 5b are respectively generated by the permanent magnet as shown in FIG. 2(C). The waveform corresponds to the deviation of 2, 2, . . . .

"Effects of the Invention" As explained above, the present invention has the advantage of magnetizing the magnetic material used for position detection of the field magnet by the magnetic flux of the field magnets arranged in the field core. Since the magnetic poles of the permanent magnet have the same pitch as the magnetic poles of the permanent magnet, the position of the magnetic pole of the permanent magnet can be accurately detected, and speed ripples can be reduced.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a magnetization method according to an embodiment of the present invention, FIG. 2 is an explanatory diagram illustrating the relationship between the permanent magnet and magnetic material of the same embodiment, and the detection signal by the sensor, and FIG. FIG. 4 is an explanatory diagram illustrating the relationship between a conventional permanent magnet and a detection signal from a sensor, and FIG. 5 is an explanatory diagram illustrating a conventional magnetization method. 2...Permanent magnet (field magnet), 6...
Magnetic material, 7...Back plate.

Claims (1)

[Claims] Magnetization of a position detection magnet, characterized in that a magnetic material used for position detection of the field magnet is brought into close contact with field magnets arranged in advance, and the magnetic material is magnetized by the magnetic flux of the field magnet. Method.