JPS61266056A - Linear motor - Google Patents

Abstract

PURPOSE:To produce a linear motor having small size and weight and high performance with an inexpensive material by using a rare earth metal permanent magnet made of rare earth metal, iron and boron as a basic composition in a magnetic circuit. CONSTITUTION:In a linear motor in which a permanent magnet 2 is used at a part of a magnetic circuit, a rare earth metal permanent magnet made of rare earth metal (R), iron (Fe) and boron (B) as a basic composition is used as the rare earth metal permanent magnet. As a representative example of such a permanent magnet there is an Nd-Fe-B magnet, and one or more types of various rare earth metals may be used as the R. Part of the Fe may be substituted by a transient metal such as Co. Since such a permanent magnet has a low price and excellent magnetic properties, a linear motor having small size and weight and high performance can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a linear motor using rare earth permanent magnets whose basic composition is RF and -B.

[Summary of the invention]

The present invention realizes a small, lightweight, high-performance linear motor at low cost by using rare earth permanent magnets whose basic composition is RF and -B in a linear motor using permanent magnets in the magnetic circuit. It is something.

[Conventional technology]

Typical permanent magnets conventionally used in motors include alnico magnets, ferrite magnets, and rare earth cobalt magnets. Figure 6 shows a comparison diagram of the characteristics of these magnets.Each item is shown in the base of alnico and rare earth cobalt. The meaning of each signal is shown in Table 1.

Table 1 The magnetic properties required for permanent magnets for motors are as follows:
The residual magnetic flux density Bf is large h, and the coercive force H.

It is important that the value is large. Alnico magnets are H
, is small, and 16 stones are small, so B is small, so
Rare earth cobalt magnets have been developed and are used as permanent magnets with excellent magnetic properties.

[Problems and objects to be solved by the invention] However, the above-mentioned rare earth cobalt magnet is expensive as shown in Figure 6, and this is because samarium (Sm) is used as the rare earth element.
)'i for i and.

This is due to the use of extremely expensive Copal (Go), and when used as a permanent magnet for a motor, although it has high performance, it becomes extremely expensive.Therefore, the present invention solves one or more of the following problems. The purpose is to obtain excellent magnetic properties using low-cost raw materials. A small, lightweight, high-performance linear motor using rare earth permanent magnets (hereinafter referred to as R-Fg-B magnets) whose basic composition is R-7, -B? It's there to provide.

[Means for solving problems]

In the IJ near motor of the present invention, the basic composition of the magnetic circuit VC1 is rare earth metal (R), iron (Fe), and boron (B).
It is characterized by using a rare earth permanent magnet consisting of.

Furthermore, the basic composition is R,? , and B are known as Nd-p, -B magnets, but R
As & ” e Ca e Pr s Ndeε 1'm, am, 'Iru, Gd, Tb, Dy, Tlo.

Kr, T'm, Y6. It is sufficient if it is above one or two of the rare earth metals of L- and L-.

Furthermore, by replacing a portion of F- (2 cm), the Curie temperature can be improved, and the temperature coefficient of Br can also be improved.
Similar improvements can be achieved by replacing '# with other transition metal groups.

[Implementation row]

EMBODIMENT OF THE INVENTION Below, one embodiment of the present invention will be described in detail.

Figure 1 shows the structure of an IJ near motor using R-Pg-Be & stone.The magnet 2 is magnetized in the thickness direction, and the coil moves when current is passed through the coil 1. It becomes. The basic composition R of the magnet is kT
Light rare earth elements other than JcL are used. Figure 8 shows an example of the composition of monazite ore (b) containing a large amount of light rare earth elements. E
3tn-c.

Compared to 6 stones, R-IPg-BIa stones are extremely effective as permanent magnets for linear motors in terms of supply and price. In terms of magnetic properties, R
-Nd-F, - exhibiting excellent characteristics among -F and -B magnets
A comparison between the B magnet and the 13m-Co magnet is shown in FIG. 7. The meaning of each symbol is shown in the table.

Table 2, Figure 7, shows the characteristic values of the E m -G o @ stone, with the characteristic value of the Nd-The-B magnet being 100.

Within the desired conditions when used in linear motors.

The only drawback of R-F and -B magnets is that the temperature coefficient of Br is large, but this is hardly a problem when used at room temperature, and it can be improved considerably by replacing the undefeated cm, so it is suitable as a magnet for linear motors. This is not a problem.

Next, the relationship between the magnetic characteristics of the linear motor shown in FIG. 1 and the custom-made linear motor will be explained. Generally, the relationship between coil voltage gj and coil displacement X is represented by a block diagram as shown in FIG.

Here, K, = l/KF T□=L/R T2 = m e R / K F” The meaning of each variable is shown in Table 3.

Table 3 FIG. 4 is a graph showing the relationship between the force constant IF, which is a parameter representing the thrust characteristics of the linear motor, and the magnetic flux density Bm of the magnetic circuit, and KF increases as B, etc. increases. When the magnet shapes are the same, the R-Fg-B magnet has a larger Bm than the Bm-Co magnet, so the K
F increases and thrust characteristics improve.

Also, position as shown in Figure 3! ! When a linear motor is used as the actuator of the system, the gain of the amplifier 4 should be set as large as possible in order to reduce positioning errors, but an upper limit is set to ensure the stability of the control system. The lK5 diagram shows the upper limit of K and the “1*Tl” shown earlier.
In this diagram, Tls TR is below the stability limit curve.
There must exist a point P determined by Here, if Bfnt- is increased, T snow will decrease and K can be set larger. In other words, conventional 08m-C.

If you change the magnet to R-7, -Bl@5 and increase Bmt, the thrust customization will improve and positioning will be improved! When using a linear motor as an actuator, it is possible to set a high control gain.

〔Effect of the invention〕

As described above, according to the present invention, by using R+yl+n magnets as the permanent magnets of the linear motor, high thrust characteristics can be obtained and positioning can be achieved! ! ! When used as the rumored actuator, the conventional am-C.

Since the control gain can be set higher than when a magnet is used, the positioning error can be reduced.

In addition, Fi is a cost issue, and Srn and C are resources.
, to use N d ′P ′F g, which is abundant compared to .

Since the R-Fg-Be1 stone is already in a more advantageous state than the Eim-Co magnet, the cost of the linear motor can be kept low, and a linear motor with extremely high cost performance can be realized.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of a linear motor of the present invention. Figure 2 is a linear motor block diagram. Figure 3 is a block diagram of the positioning mechanism. Figure 4 is a custom diagram of force constant changes. FIG. 5 is an explanatory diagram of stability limits. FIG. 6 is a comparison diagram of conventional magnet characteristics. Figure 7 is a comparison diagram of the characteristics of a samarium/copal (samarium/copal) 4-stone magnet and a rare earth-iron-boron magnet. Figure 8 is a graph of rare earth elements in major ores, and! Figure 8 (α>1i monazite ore, same <b> tit
Indicates pastonezite ore. that's all

Claims (2)

[Claims] (1) A linear motor using permanent magnets in a magnetic circuit, characterized in that a rare earth permanent magnet whose basic composition is a rare earth metal (R), iron (Fe), and boron (B) is used. (2) The linear motor according to claim 1, wherein a part of the Fe is replaced with at least one transition metal group other than Fe, such as cobalt (Co).